West Coast Of South Korea Research Articles

Analysis of the Eddy current of water heating device to convert wind energy directly into heat: Case study maldo island, South Korea

The Eddy Current of Water Heating (ECWH) system introduces a pioneering approach for converting wind energy into heat, marking a significant step in renewable energy technology. The current study focuses on refining the ECWH system by evaluating eight distinct heat generator models. Each model is selected based on its magnet configurations and pole numbers to maximize power efficiency at rotational speeds ranging from 100 to 500 rpm. This selection strategy is designed to provide a deep understanding of not only system efficiency across a spectrum of technical specifications but also the practical limitations of experimental research considerations. Energy efficiency is thoroughly analyzed for four models over a power input range of 120 to 2193 W. Wind speed data collected over a year from Maldo Island, west coast of South Korea, simulates the Weibull distribution of wind speeds and estimates total power production by employing the QBlade software. This study aims to explore the practicality of converting wind's kinetic energy directly into thermal energy through the ECWH system. Our findings indicate that the ECWH system outperforms conventional permanent magnet alternators, particularly in its ability to generate more power at lower angular velocities and wind speeds—a crucial feature for locales like Maldo Island, where typical wind speeds range from 3 to 6 m/s, considered low to moderate. With an energy efficiency exceeding 90%, generating an annual power output of 2266.3 kWh, and achieving a facility utilization rate of 10.34%, the results underscore the potential of the ECWH system as an efficient and sustainable solution for heating in areas with similar wind conditions.

Evaluating the Potential of Korean Mudflat-Derived Penicillium nalgiovense SJ02 as a Fungal Starter for Manufacturing Fermented Sausage.

The objective of this study was to isolate, identify, and evaluate novel Korean starter cultures for use in fermented sausages. A total of 72 strains were isolated from various indigenous sources, including Nuruk, Jeotgal, and mudflats on the west coast of South Korea. Two strains were identified as Penicillium nalgiovense (SD01 and SJ02), a traditional starter used in the production of fermented sausages. A comparative analysis was performed between SD01 and SJ02 using the commercial starter culture (M600). Strain SJ02 exhibited superior lipolytic and proteolytic activities, as well as an enhanced growth rate at the optimal salinity level of 2% NaCl compared to M600. No significant differences were observed in thiobarbituric acid reactive substances values, sausage colors, and texture properties between SJ02 and M600 fermented sausages, except for adhesiveness. Profiles of mycotoxin-related genes were similar for both strains. Electronic nose analysis revealed distinct aroma profiles between SJ02 and M600 fermented sausages, with a relatively higher levels of propan-2-one and butyl butanoate in SJ02, and a higher level of ethanol and propanal in M600. In electronic tongue analysis, there was no significant differences in taste characteristics between SJ02 and M600. These results indicate that P. nalgiovense SJ02 is a potential starter culture to produce dry fermented sausages, enhancing Korean style cured meat processing industry.

Measurements of underwater noise genenrated during wind turbine operation in Korea Southwest Offshore Wind Farm

Offshore wind power generation, a representative eco-friendly energy generation, is known as one of the promising solutions for sustainable development. However, the potential negative impact of underwater noise emitted from wind turbine operation on the marine ecosystem may limit development. Measurements of underwater noise generated from the operation of a 3-MW offshore wind turbine in the Korea Southwest Offshore Wind Farm located off the southwest coast of Korea were made twice in late February to early March and November 2021, and the acoustic characteristics of operational noise with wind speed, rotor speed, and tower vibration were investigated. As a result, the tonal frequencies of the underwater noise and tower vibration acceleration signal coincided, and their changes showed high correlations with the wind speed and rotor speed. Our results may be used as a reference to evaluate the impact of underwater operational noise of offshore wind turbines on the marine environment.

Measurements of underwater operational noise caused by offshore wind turbine off the southwest coast of Korea

As interest in the development of renewable energy increases, a large number of offshore wind farms are being built worldwide. Accordingly, the potential impacts of underwater operational noise on marine ecosystems have become an issue, and thus it is necessary to understand the mechanisms and acoustic characteristics of underwater operational noise for the environmental impact assessment. For this paper, underwater noise was measured for about 10 days near a 3-MW wind turbine off the southwest coast of Korea, and the acoustic characteristics of the operational noise and its relationship with rotor speed were investigated. The tonal frequencies of the underwater operational noise varied with rotor speed, and particularly the peak level at a frequency of ~198 Hz increased by ~20 dB or more at the rated rotor speed. Additional experiments were conducted to determine the relationship between underwater noise and wind turbine tower vibration, and finally, the underwater noise correlated highly with the tower vibration acceleration signal, wind speed, and rotor speed, with correlation coefficients of 0.95 or higher.

Physiological and biochemical responses of Limonium tetragonum to NaCl concentrations in hydroponic solution.

Limonium (L.) tetragonum (Thunb.) A. A. Bullock, a halophyte that grows all over the southwest coast of Korea, is a medicinal plant with various pharmacological effects. The salt defense mechanism stimulates the biosynthesis of various secondary metabolites and improves functional substances. In this study, we investigated the optimal NaCl concentration for the growth and enhancement of secondary metabolites in hydroponically grown L. tetragonum. The seedlings grown for 3 weeks in a hydroponic cultivation system were treated with 0-, 25-, 50-, 75-, and 100-mM NaCl in Hoagland's nutrient solution for 8 weeks. No significant effect on the growth and chlorophyll fluorescence was observed for the NaCl concentrations below 100-mM. The increase in the NaCl concentration resulted in the decrease in the water potential of the L. tetragonum leaves. The Na+ content accumulated in the aerial part increased rapidly and the content of K+, which acts as an antagonist, decreased with the increase in NaCl concentrations in hydroponics. The total amino acid content of L. tetragonum decreased compared to the 0-mM NaCl, and most of the amino acid content decreased as the NaCl concentration increased. In contrast, the content of urea, proline (Pro), β-alanine, ornithine, and arginine was increased with an increase in NaCl concentration. The Pro content at 100-mM NaCl accounted for 60% of the total amino acids and was found to be a major osmoregulator as an important component of the salt defense mechanisms. The top five compounds identified in the L. tetragonum were classified as flavonoids while the flavanone compound was detected only in the NaCl treatments. A total of four myricetin glycosides were increased in comparison to the 0-mM NaCl. Among the differentially expressed genes, a significantly large change in Gene ontology was seen in the circadian rhythm. NaCl treatment enhanced the flavonoid-based substances of L. tetragonum. The optimum NaCl concentration for the enhancement of secondary metabolites of the L. tetragonum in the vertical farm-hydroponic cultivation system was 75-mM NaCl.

Ocean oil spill detection from SAR images based on multi-channel deep learning semantic segmentation

One of the major threats to marine ecosystems is pollution, particularly, that associated with the offshore oil and gas industry. Oil spills occur in the world's oceans every day, either as large-scale spews from drilling-rig or tanker accidents, or as smaller discharges from all sorts of sea-going vessels. In order to contribute to the timely detection and monitoring of oil spills over the oceans, we propose a new Multi-channel Deep Neural Network (M-DNN) segmentation model and a new and effective Synthetic Aperture Radar (SAR) image dataset, that enable us to emit forewarnings in a prompt and reliable manner. Our proposed M-DNN is a pixel-level segmentation model intended to improve previous DNN oil-spill detection models, by taking into account multiple input channels, complex oil shapes at different scales (dimensions) and evolution in time, and look-alikes from low wind speed conditions. Our methodology consists of the following components: 1) New Multi-channel SAR Image Database Development; 2) Multi-Channel DNN Model based on U-net and ResNet; and 3) Multi-channel DNN Training and Transfer Learning. Due to the lack of public oil spill databases guaranteeing a correct learning process of the M-DNN, we developed our own database consisting of 16 ENVISAT-ASAR images acquired over the Gulf of Mexico during the Deepwater Horizon (DWH) blowout, off the west coast of South Korea during the Hebei Spirit oil tanker collision, and over the Black Sea. These images were pre-processed to create a 3-channel input image IM = {IO, IW, IV}, to feed in and train our M-DNN. The first channel IO represents the radiometric values of the original SAR Images, the second and third channels are derived from IO; in particular, IW represents the output of the wind speed estimation using CMOD5 algorithm (Hersbach et al., 2003) and IV represents the variance of IO that incorporates texture information and at the same time encapsulates oil spill transition regions. IM channels were split and linearly transformed for data augmentation (rotation and reflection) to obtain a total of 80,772 sub-images of 224 × 224 pixels. From the entire database, 80 % of the sub-images were used in the DNN training process, the remaining (20 %) was used for testing our final architecture. Our experimental results show higher pixel-level classification accuracy when 2 or 3 channels are used in the M-DNN, reaching an accuracy of 98.56 % (the highest score reported in the literature for DNN models). Additionally, our M-DNN model provides fast training convergence rate (about 14 times better on the average than previous works), which proves the effectiveness of our proposed method. According to our knowledge, our work is the first multi-channel DNN based scheme for the classification of oil spills at different scales.

Meteorological Water Surface Disturbance in Tsunami Frequency Band near Ulleung Island on the East Sea of Korea

Lee, E.; Shin, S.; Park, J.-N., and Park, S.-C., 2023. Meteorological water surface disturbance in tsunami frequency band near Ulleung Island on the East Sea of Korea. Journal of Coastal Research, 39(1), 191–198. Charlotte (North Carolina), ISSN 0749-0208. The probability of exposure to coastal hazards has been increasing recently due to climate change. Meteotsunamis, one of the coastal hazards, are generated around the world by meteorological forcing, and their frequency band is 2 minutes to 3 hours, similar to earthquake-induced tsunamis. Although the west coast of South Korea has been unexpectedly affected, incurring casualties and property losses in 2007 and 2008, there are no documented cases in the East Sea of Korea. However, the surge gauge located on Ulleung Island (the easternmost part of Korea), operated by Korea Meteorological Administration to detect tsunamis, observed two meteotsunamis in January and April 2020. So, this study aimed to quantify the two meteotsunamis based on sea-level measurements and atmospheric observations. The results of the study show the maximum peak-to-trough wave height was 99.86 cm greater than the wave height of the 2011 Tohoku tsunami obtained by the Ulleung surge gauge. This reveals that the meteotsunami monitoring system should be improved based on the deep analysis of sea level and atmospheric observations on the East Sea of Korea to respond to climate change.

An investigation of petrochemical emissions during KORUS-AQ: Ozone production, reactive nitrogen evolution, and aerosol production

Emissions and secondary photochemical products from the Daesan petrochemical complex (DPCC), on the west coast of South Korea, were measured from the NASA DC-8 research aircraft during the Korea-United States Air Quality campaign in 2016. The chemical evolution of petrochemical emissions was examined utilizing near-source and downwind plume transects. Small alkenes, such as ethene (C2H4), propene (C3H6), and 1,3-butadiene (C4H6), dominated the hydroxyl (OH) radical reactivity near the source region. The oxidation of these alkenes in the petrochemical plumes led to efficient conversion of nitrogen oxides (NOx) to nitric acid (HNO3), peroxycarboxylic nitric anhydrides (PANs), and alkyl nitrates (ANs), where the sum of the speciated reactive nitrogen contributes more than 80% of NOy within a few hours. Large enhancements of short-lived NOx oxidation products, such as hydroxy nitrates (HNs) and peroxyacrylic nitric anhydride, were observed, in conjunction with high ozone levels of up to 250 ppb, which are attributed to oxidation of alkenes such as 1,3-butadiene. Instantaneous ozone production rates, P(O3), near and downwind of the DPCC ranged from 9 to 24 ppb h−1, which were higher than those over Seoul. Ozone production efficiencies ranged from 6 to 10 downwind of the DPCC and were lower than 10 over Seoul. The contributions of alkenes to the instantaneous secondary organic aerosol (SOA) production rate, P(SOA), were estimated to be comparable to those of more common SOA precursors such as aromatics at intermediate distances from the DPCC. A model case study constrained to an extensive set of observations provided a diagnostic of petrochemical plume chemistry. The simulated plume chemistry reproduced the observed evolution of ozone and short-lived reactive nitrogen compounds, such as PANs and HNs as well as the rate and efficiency of ozone production. The simulated peroxy nitrates (PNs) budget included large contributions (approximately 30%) from unmeasured PNs including peroxyhydroxyacetic nitric anhydride and peroxybenzoic nitric anhydride. The large, predicted levels of these PAN compounds suggest their potential importance in chemical evolution of petrochemical plumes. One unique feature of the DPCC plumes is the substantial contribution of 1,3-butadiene to ozone and potentially SOA production. This work suggests that reductions in small alkene, especially 1,3-butadiene, emissions from the DPCC should be a priority for reducing downwind ozone.

Wind-driven retreat of cold water pool and abrupt sea temperature rise off the southwest coast of Korea in summer 2017

Variations in seawater temperature have a critical influence on marine ecosystems and aquaculture industries in coastal regions. From July 25 to August 5, 2017, the sea surface temperature off the southwestern coast of Korea rose rapidly from 17.1 °C to 27.3 °C, which induced environmental stress in marine organisms such as farmed abalone. This study investigated the cause of this abrupt sea temperature rise. Westerly winds from July 1 to 25 were favorable for the upwelling of cold subsurface water along the bottom slope in this coastal region, helping maintain cool surface water temperatures. As the wind changed to easterly, the cold subsurface water moved away and warmer, fresher surface water moved into the coastal region, where the surface currents changed from a southeastward flow to a northeastward flow from July 25 to August 5. Thus, to maintain stable, cool seawater temperatures during summer, both cold water supply and upwelling wind conditions are essential. The analysis of water masses indicated that the cold water was formed by the mixing of the Tsushima Warm Current Water and Yellow Sea Bottom Water in the northern East China Sea. The cold water advected eastward and formed a cold water pool in the intermediate depths (30–80 m) of the northern Jeju Strait, providing cold water to the coastal region during the upwelling period. The westerly winds were disrupted by the approach of a typhoon, which discontinued the supply of bottom cold water. The physical processes identified in this study will help predict short-term increases in water temperature and can assist in the development of countermeasures for the aquaculture industry against the negative effects of abrupt environmental changes.

Complexity, Uncertainty and Ambiguity in Korean Military Leadership

In South Korea, being the only divided country in the world and thus being under extreme tension, the weight and the importance that the Korean military carries is surely different from those of other militaries. Under this exceptional circumstance, it is not an overstatement to say that the Korean military faces a more complex and difficult challenge than any other organization and requires a higher state of leadership. The sinking of the Cheonan navy vessel and the bombardment of Yeonpyeong Island on the west coast of South Korea in 2010 were opportunities to look back upon the present state of the leadership of the Korean military. Internally, the Korean military is making efforts to justify its existence, and within the military, it is trying to develop its organizational leadership that can contribute to meeting its objectives. The discussion across society centered on national defense reforms supports this notion, which tells us that reflecting on the organizational leadership to perform the roles of the military is the central task in order to shift the organizational paradigm that meets the changes of security environments surrounding south Korea and far eastern Asia. Under these circumstances, it is imperative and timely to discuss a few phenomena that hinder the development of the military leadership and to look for alternatives.

10 years long-term assessment on characterizing spatiotemporal trend and source apportionment of metal(loid)s in terrestrial soils along the west coast of South Korea

Long-term trends in the spatial distributions and sources of metal(loid)s in soils adjacent to the west coastal areas of South Korea have been systematically investigated for 10 years (2010–2019). Monitoring in 17 sites clearly showed site- and region-specific distributions, being associated with land use type (significant differences, as road > agriculture > wild) (P < 0.05), rather than temporal variation. The great concentrations of all metal(loid)s were found near Lake Shihwa (LS) and Geum River (GG), near the road, indicating that transportation activity was the main source of metal(loid)s contamination in soil. Especially, Cd (0.5 mg kg−1), Hg (0.04 mg kg−1), Pb (65 mg kg−1), and Zn (184 mg kg−1), related to the transportation activity near the road, showed twice greater than other land use types, on average. The concentration of metal(loid)s in each site and with the same land use type did not greatly vary over the years, with no significant annual difference (P > 0.05). The degree of metal(loid)s contamination compared to the background levels was identified in the order of Pb > Zn > Cr > Cu > As>Cd > Ni > Hg, with the contaminated hotspots mostly in LS or GG. The potential ecological risk was evidenced for Cd and Hg, but such a trend was temporally irregular over the years, indicating site-specificity. The sources of metal(loid)s were carefully determined as natural (20%), fuel combustion & agricultural pollution (43%), and vehicular emissions (37%) using the Positive Matrix Factorization model. The relative contribution of each source to contamination over the last decade was found to be similar, supporting that site-dependent lesser variation in metal(loid)s contamination in the coastal areas of South Korea. Overall, the distribution of metal(loid)s in the soil near the west coastal areas over the last decade largely depended on land use activities, and contamination degree was associated with non-point sources, such as transportation and fuel combustion.

Measurements and Spatial Distribution Simulation of Impact Pile Driving Underwater Noise Generated During the Construction of Offshore Wind Power Plant Off the Southwest Coast of Korea

Offshore wind power plants are under construction worldwide, and concerns about the adverse effects of underwater noise generated during their construction on the marine environment are increasing. As part of an environmental impact assessment, underwater noise generated by impact pile driving was measured during the construction of an offshore wind farm off the southwest coast of Korea. The sound exposure levels of impact pile driving noise were estimated as a function of distance and compared with those predicted by a damped cylindrical spreading model and broadband parabolic equation simulation. Source level at 1 m was estimated to be in a range of 183–184 dB re 1μPa2s in the sound exposure level based on the model predictions and it tended to decrease by 21log⁡r as the distance increased. Finally, the spatial distribution of impact pile driving noise was predicted. This result, if combined with noise-induced damage thresholds for marine life, may be used to assess the effects of wind farm construction on marine ecosystems.

Spatiotemporal Evaluation of Water Quality and Hazardous Substances in Small Coastal Streams According to Watershed Characteristics

In this study, spatial and temporal changes of eight water quality indicators and 30 types of hazardous substances including volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, and inorganic matters for the small coastal streams along the West Coast of South Korea were investigated. In coastal streams with clear seasonal changes in water quality, larger watershed areas led to greater contamination by particulate matter (i.e., suspended solids, r = 0.89), and smaller watershed areas led to greater contamination by organic matter (i.e., BOD, r = −0.78). The concentration of VOCs and pesticides was higher in agricultural areas, and those of SVOCs and metals were often higher in urban areas. According to the principal component analysis (PCA), during the wet season, the fluctuation in the water quality of coastal streams was higher in urban areas than in agricultural areas. Furthermore, coastal streams in residential areas exhibited higher levels of SVOCs, and those in industrial areas exhibited higher levels of metallic substances. Based on these results, the spatial and temporal trends of water quality and hazardous substances were obtained according to watershed characteristics, thereby clarifying the pollution characteristics of small-scale coastal streams and the major influencing factors.

A Study on Cultural Urban Regeneration Using Modern Industrial Resources: Focusing on the Site-Specific Cultural Places of Gunsan, South Korea

Gunsan is a port city located on the west coast of South Korea. After the port was opened in 1899, foreign concessions were formed there, and the modern city began to be formed in accordance with Japanese colonial policy. This region grew into a modern port city by exporting rice harvested from the plains in the hinterland to Japan and managed and controlled commercial and industrial products of the surrounding area. Modern industrial facilities such as warehouses, financial, and administration facilities necessary for seizing the food resources for the colony were built there, and Gunsan developed as a hub city in the southwestern region of South Korea during the 1930s. However, after liberation in 1945, the number of modern industrial facilities in this area, which contained traces of Japanese imperialism, gradually declined. In the 2000s, as urbanisation accelerated, the problem of abandoned modern industrial facilities was raised, and the necessity of urban regeneration by utilizing the modern industrial facilities scattered in the original downtown of Gunsan emerged. The purpose of this paper is to examine the regional activation and cultural regeneration of the city by using modern industrial facilities as cultural places and targeting the case of Gunsan, which was developed as a colonial-planned city. In particular, through field studies, this paper examines those cultural spaces, utilising modern industrial facilities that contribute to the formation of regional uniqueness, mediate local communities, and create future values of sustainable cultural regeneration.

Comparison of Methods for Determining Erosion Threshold of Cohesive Sediments Using a Microcosm System

Erosion of cohesive sediments is a ubiquitous phenomenon in estuarine and intertidal environments. Several methods have been proposed to determine the surface erosion threshold (τc0), which are still debatable because of the numerous and uncertain definitions. Based on erosion microcosm experiments, we have compared three different methods using (1) eroded mass (EM), (2) erosion rate (ER), and (3) suspended sediment concentration (SSC), and suggested a suitable method for revealing the variation of erodibility in intertidal sediments. Erosion experiments using a microcosm system were carried out in the Muuido tidal flat, west coast of South Korea. The mean values of τc0 for three methods were: 0.20 ± 0.08 Pa (EM); 0.18 ± 0.07 Pa (ER); and (3) 0.17 ± 0.09 Pa (SSC). The SSC method yielded the lowest τc0, due to the outflow of suspended sediment from the erosion chamber of the microcosm. This was because SSC gradually decreased with time after depleting the erodible sediment at a given bed shear stress (τb). Therefore, the regression between SSC and applied τb might skew an x-intercept, resulting in the underestimation (or “not-determined”) of τc0. The EM method yielded robust and accurate (within the range of τb step at which erosion begins) results. The EM method represents how the erodible depth thickens as τb increases and therefore seems better suited than the SSC and ER methods for representing depth-limited erosion of cohesive sediments. Furthermore, this study identified the spatiotemporal variations of τc0 by EM method in an intertidal flat. The τc0 in mud flat was about two times higher than that in mixed flat. Compared to the end of tidal emersion, the sediment was 10–40% more erodible at the beginning stage.

Changes in Power Generation at Sihwa Lake Tidal Power Plant with the Installation of Submerged Breakwaters

Kim, T.-W.; Kim, Y.-J.; Yoon J.-S., and Kim, M.-K., 2021. Changes in power generation at Sihwa Lake Tidal Power Plant with the installation of submerged breakwaters. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 146–150. Coconut Creek (Florida), ISSN 0749-0208. Tidal power generation uses potential energy generated by vertical movements of the sea level to run a hydro turbine to produce electricity; thus, it is suitable for areas with large differences between tidal waves. The Sihwa Lake Tidal Power Plant situated on the west coast of South Korea is located at the center of the 11.2-km-long Sihwa Seawall. It generates power by using the increased water level in the outer region during ebb, and it discharges the seawater inflow caused by power generation during flood. In this study, the EFDC (Environmental Fluid Dynamics Code model), which can reproduce the operation patterns of the Sihwa sluice gate and considers permeable structures, was applied to predict the effect of changes in seawater flow resulting from the installation of impact reduction facilities on the nearby offshore of the Sihwa Lake Tidal Power Plant. To calculate the amount of power generated using a numerical model, a year-long daily operation record of the tidal power plant in 2013 was analyzed and used as input conditions (sluice gate operation, runoff) of the numerical model. In addition, a relational expression was derived using the data—inner/outer water-level difference (ΔH), hydro turbine water flowrate (Q), and power generated (W)—and the power output was calculated using the inflow rate calculated by the numerical model.

Optimization of Influencing Factors in Tidal Current Data Assimilation Modeling in Macro Tidal Estuary, Gyeonggi Bay, South Korea

Gu, B.-H.; Woo, S.-B., and Kim, S., 2021. Optimization of influencing factors in tidal current data assimilation modeling in macro tidal estuary, Gyeonggi Bay, South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 66–70. Coconut Creek (Florida), ISSN 0749-0208. The study investigates the effect of the model prediction accuracy improvement using data assimilation technique in macro-tidal estuary, such as the Gyeonggi Bay (GGB), South Korea. The observation data used in this study is a tidal current measurement from Acoustic Doppler Current Profiler (ADCP) mooring device. GGB is located at the middle west coast of South Korea, and it is semi-closed estuary that has a tidal range over 6.8 m. To take the irregularity of coastline into account, this study utilized the Finite Volume Coastal Ocean Model (FVCOM), which has the flexible advantage of grid resolution by using unstructured triangular grid system. When applying data assimilation into the coastal model, various parameters, such as scaling factors and correlation lengths are needed to be adjusted to find out the best performance. Total 25 cases used in Taylor diagram showed that different influencing factors are required to be optimized at each observation location. It means that parameters in data assimilation depend on the physical dynamic system via complicated geometry. The optimized parameters not only increase by the tidal range but also it is offset by the effect of river discharge. The horizontal influence range of data assimilation with all observed locations becomes even less than the result applying only one location. It is estimated that the phenomena occurred due to strong tidal currents and interference between the range of influence. The sensitivity of data assimilation parameters in tidally dominated coastal area indicates that a systematic way of choosing the most optimized site-specific parameters are required in macro tidal area.

Tidal Creek Mapping from Airborne LiDAR Data Using Multi-resolution Cloth Simulation Filtering

Kim, H.; Lee, J., and Kim, Y., 2021. Tidal creek mapping from airborne LiDAR data using multi-resolution cloth simulation filtering. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 86–90. Coconut Creek (Florida), ISSN 0749-0208. Tidal creeks are transitional waterways promoting the evolution and expansion of tidal flats. The precise and objective delineation of tidal creeks is critical for monitoring the characteristics, formation, and evolution of tidal flats. Airborne light detection and ranging (LiDAR) data are the most widely used source of tidal topography information, since they can provide precise terrain information over wide areas. However, existing tidal creek extraction methods using airborne LiDAR data have limitations, such as the necessity of excessive user intervention and a lack of adaptability to the various shapes and widths of tidal creeks. The morphological irregularities, complexity, and diverse widths (from a few centimeters to several kilometers) of tidal creeks, complicates their automatic or manual extraction from LiDAR data. In this study, we propose an effective and practical method for the mapping of tidal creeks with a wide range of widths. Here, cloth simulation filtering (CSF), a verified ground filtering technique used to filter off-ground objects from point cloud in land LiDAR surveys, was adopted and modified. By sequentially filtering the creek points through a hypothetical cloth with an increasingly larger grid resolution, the proposed multi-resolution CSF can extract huge tidal creeks without compromising the details of narrow creeks. This sequential filtering is based on local thresholds calculated using the creek points extracted during the previous filtering and does not require empirical parameter adjustments. The results of an experimental evaluation based on airborne LiDAR data collected over the west coast of South Korea indicate that the accuracy of the proposed method is high (Kappa > 0.8) and superior to that of results obtained through an user parameter.

Intelligent Buoy System (INBUS): Automatic Lifting Observation System for Macrotidal Coastal Waters

The west coast of South Korea is characterized by a wide macrotidal area with a maximum tidal range of ∼10 m. The sea surface elevation varies with the tidal phase, which leads to significant changes in the vertical structure of the physical, chemical, and biological properties of the water column, especially when the interaction by waves and/or the freshwater and sediment input from the river increases. Under such conditions, it is difficult to carry out continuous and consistent measurements of the vertical structures of the water qualities using a conventional observation system that is fixed to the seabed or sea surface because the thickness of the water column constantly changes. Based on the demand for long-term observations of the vertical structures of the water properties in macrotidal environments, the Intelligent Buoy System (INBUS) was developed by the Korea Institute of Ocean Science and Technology (KIOST). INBUS is a buoy equipped with an instrument frame, which is similar to other buoys that are fixed to the sea surface. During every measurement, INBUS detects the water depth and sends the frame down to the seabed to measure the water quality at every vertical level set up in the system. For example, if N levels are set in INBUS, the water depth of each measurement is divided by N layers and the instruments in the lifting frame measure the water properties of each of the N layers while they are descending to the bottom. Based on this procedure, the vertical structure of the water column is consistently measured in N layers regardless of changes of the water depth due to tides and waves. The lifting and measuring process is automatically controlled by INBUS once it is set up in the system. In addition, because INBUS allows bidirectional communication through code division multiple access (CDMA), the system can be controlled by stations on land. If the CDMA communication becomes inoperable owing to extreme wave conditions or the buoy is lost because of incidents such as a collision with a ship, the location of INBUS can be tracked by low-earth-orbit satellites.

Marine Benthic Algal Community at Dadohaehaesang National Park, South-west Coast of Korea

Marine Benthic Algal Community at Dadohaehaesang National Park, South-west Coast of Korea