Daejeon City Research Articles

CPTED사업을 위한 솔라표지병 설치기준에 관한 연구

This study aims to establish installation standards for solar road studs, which are frequently utilized by law enforcement and municipal authorities as part of Crime Prevention Through Environmental Design initiatives. In the wake of the Gangnam Station incident, there has been a significant increase in societal concern regarding women's safety, leading to greater attention on solar road studs as a means to enhance pedestrian safety in poorly lit alleyways. Solar road studs are devices that store solar energy during the day and emit light at night, offering benefits such as low maintenance costs and environmental sustainability. This research, using the case of Daejeon City, assesses the psychological impact of the color and spacing of solar road studs on the perceived safety of participants. The findings reveal that green solar road studs installed at 4-meter intervals provide the highest sense of security among participants. Although white solar road studs may also be effective in low-light conditions, their combination with street lighting may reduce visibility, necessitating careful consideration. Based on these findings, this study proposes optimal installation standards for solar road studs to maximize their effectiveness in crime prevention. It specifically recommends the use of green solar road studs at 4-meter intervals as the most effective configuration. The study aims to clarify installation guidelines to enhance the crime prevention potential of solar road studs, thereby offering practical insights for practitioners in the field.

보육교사의 공감능력과 영유아 권리존중 간 관계

Objectives The purpose of this study is, first, to investigate the relationship between childcare teachers' empathy, respect for infants' rights, and childcare teachers' sensitivity, and secondly, to verify the mediating effect of sensitivity in the relationship between empathy and respect for infants' rights. Methods Empathy, respect for infants' rights, and sensitivity tests were conducted on 337 infant and toddler teachers at daycare centers located in South Chungcheong Province, Daejeon City, and Sejong City. Correlation analysis of each variable was conducted, and SPSS Process Macro Model 4 was used to verify the mediating effect of sensitivity in the impact of childcare teachers' empathy on respect for infants' rights. Results As a result of this study, first, it was found that childcare teachers' empathy, respect for infants' rights, and sensitivity were all significantly correlated. Second, the sensitivity of the childcare teacher completely mediated the relationship between respect for infants and children's rights. Sensitive interaction, a subfactor of sensitivity, fully mediated the relationship between the two variables, and insensitive interaction partially mediated the relationship between the two variables. Conclusions The results of this study showed the importance of enhancing childcare teachers' empathy and sensitivity in order to improve the quality of respect for infants' rights, and suggest the need to find intervention methods to help childcare teachers improve their sensitive interactions.

Real-Time Estimation of Origin–Destination Matrices Using a Deep Neural Network for Digital Twins

The digital twin, a real-time replica of physical systems, has garnered attention as a promising tool to strategize and evaluate solutions for complex real-world issues. However, developing digital twins in the field of transportation faces significant challenges related to the real-time estimation of dynamic origin–destination (OD) matrices constrained by computation time. To bridge this gap, microscopic traffic simulations with real-time synchronization are being researched. Nonetheless, the computational issue persists, emphasizing the need for more efficient OD estimation methods. In this regard, our objective is to reduce computation time in simulation-based methods by developing a data-driven metamodel using a deep neural network. The proposed model serves to map the correlation between the OD matrix and detector data. This model simplifies the computational process using hidden layers, rather than calculating complex interactions between vehicles in the traffic simulation. Compared to conventional methods, we evaluate the capability to estimate a reasonable OD matrix within a restricted time and validate our approach using detector data from Daejeon City, South Korea. The findings indicate that by combining our data-driven metamodel with the simultaneous perturbation stochastic approximation, it becomes feasible to estimate a reasonable OD matrix within a stipulated time frame, compared to the conventional method. Given a 1-min time frame, the proposed method outperforms the conventional simulation-based method by improving the calibration performance of traffic flow by 44.5 percentage points. This paper proposes a practical and versatile approach for real-time OD estimation, laying the foundation for extending microscopic traffic simulation into the digital twin.

GENERATION Z CONSUMER PREFERENCES FOR INDONESIAN CUISINE IN SOUTH KOREA (QUANTITATIVE SURVEY ON PREFERENCES OF INDONESIAN CUISINE IN DAEJEON, SOUTH KOREA)

This study aims to determine the level of preference of Generation Z for Indonesian food in the city of Daejeon, South Korea which was reviewed from the aspects of taste, price, and ease of obtaining. The research method used in this research is the descriptive quantitative method and the data is in the form of numbers generated from the actual situation. For the results: The highest like for Indonesian food is Soto. Based on the results of the test of Homogeneity of Variances it can be concluded that the Indonesian food Bakso, Nasi Goreng, Rendang, Sate, and Soto that the researchers compared are the same (homogeneous). Based on the ANOVA results it can be concluded that the Indonesian food Bakso, Nasi Goreng, Rendang, Sate, and Soto that the researchers compared had the same average. Based on the ANOVA results it can be concluded that the Indonesian food Bakso, Nasi Goreng, Rendang, Sate, and Soto that the researchers compared has a different average.

From Prediction to Prevention: Leveraging Deep Learning in Traffic Accident Prediction Systems

We propose a novel system leveraging deep learning-based methods to predict urban traffic accidents and estimate their severity. The major challenge is the data imbalance problem in traffic accident prediction. The problem is caused by numerous zero values in the dataset due to the rarity of traffic accidents. To address the issue, we propose a grid-clustered feature map with the ideas of grids and cells. To predict the occurrence of accidents in the grid, we introduce an accident detector that combines the power of a Convolutional Neural Network (CNN) with a Deep Neural Network (DNN). Then, hierarchical DNNs are supposed to be an accident risk classifier to estimate the risk of each cell in the accident-occurrence grid. The proposed system can effectively reduce instances with no traffic accidents. Furthermore, we introduce the concept of the Accident Risk Index (ARI) to better represent the severity of risk at each cell. Also, we consider all the explanatory variables, such as dangerous driving behaviors, traffic mobility, and safety facility information, that can be related to traffic accidents. To improve the prediction accuracy, we further take into consideration all the explanatory variables, such as dangerous driving behaviors, traffic mobility, and safety facility information, that can be related to traffic accidents. In the experiment, we highlight the benefits of our method for urban traffic accident management by significantly improving model performance compared to the baselines. The feasibility and applicability of the proposed system are validated in the data of Daejeon City, Republic of Korea. The proposed prediction system can dynamically advise and recommend commuters, traffic management systems, and city planners on alternatives, optimizations, and interventions.

소통강화를 위한 교양 스페인어 문제중심학습 모형

This study aimed to design a problem-based learning model for general Spanish course to strengthen communication using learner-centered teaching methods. The subjects of this study were divided into two classes for a total of 80 freshmen students taking Spanish classes in a university in Daejeon City for 10 weeks in the second semester of 2022. After reviewing the validity of five experts, the final model was completed through learner evaluation after applying it to actual classes. The results of the expert validity test showed that the average of suitability, explanatory power, and usefulness items was 3.0 or higher, but the average of comprehension items was 2.8 and less than 3.0. The final model of problem-based learning design was completed by reflecting the results of expert validity verification and learner evaluation.

Qualitative research on the work experience of caseworkers at child protection agencies during the COVID-19 pandemic

The purpose of this study is to explore the work experience of caseworkers at child protection agencies during the COVID-19 pandemic. Six caseworkers from child protection agencies in Daejeon City were selected as participants and in-depth interviews were conducted. The collected data were analyzed using thematic analysis. The analysis yielded three themes and 10 subthemes. The three themes derived were “urgent problems to resolve amid the spread of infectious diseases,” “exhaustion of caseworkers who struggled to change work environments,” and “measures to effectively respond to infectious diseases in the field of practice.” Based on the results, the study suggested preparing non-face-to-face visit plans for children who entered the facility separate from their parents, improving the rigid organizational culture, and expanding services to prevent the exhaustion of caseworkers.

Large-Scale Network Imputation and Prediction of Traffic Volume Based on Multi-Source Data Collection System

Although newly developed traffic detectors were actively deployed to improve the accuracy and coverage of collecting city-wise traffic state information, the rapid transition of the traffic management system caused the problems of massive data corruption. For the practical application of recovering the missing values, the deep learning-based imputation technique is used, which relies on prediction performance with the consideration of dynamic spatial and temporal characteristics in the traffic state information. However, the existing method requires an assumption that the given data comprise a complete dataset from a single source based on the experiments evaluated on a small scale or long stream of freeways. In this paper, we propose a multi-variable spatio-temporal learning technique based on multi-source traffic state information, which was realized by adopting Attention-based Spatial–Temporal Graph Convolutional Networks (ASTGCN). The proposed imputation method cooperatively aggregates spatial and temporal correlation from two different types of detectors into an integrated framework, which allows us to predict missing volume regardless of the missing rate. Moreover, the study was conducted on a large-scale network that contains the entire road characteristics. Daejeon city has served as a case study to demonstrate the performance, and the results show that the mean absolute error of the proposed method is under 12 vehicles/5 min. Our work indicates that multi-source traffic state information can be utilized to impute city-wide missing traffic volume.

Health-management experiences among older women living alone during the COVID-19 pandemic: A photovoice study

Purpose: The purpose of this study was to explore the health-management experiences of older women living alone during the coronavirus disease 2019 (COVID-19) pandemic through the photovoice method. The research question was as follows: “What were the physical, psychological, and social health management experiences of older women living alone during COVID-19?”Methods: Data collection was conducted by a photovoice method. We visited the homes of 8 participants aged from 80 to 89 years old in the city of Daejeon between June 23 and July 14, 2022 using purposive sampling.Results: As a result of the photovoice study, 125 photos, 15 sub-themes, and four themes were derived. The first theme was “loneliness deepened by COVID-19”, which consisted of the following sub-themes: “lack of communication due to COVID-19”, “staying in nature”, and “aggravated loneliness during COVID-19”. The second theme was “difficulty getting out of the residence”, which included the following sub-themes: “relief stress from COVID-19”, frustrated by the difficulty of going out”, “decreased orientation and going out less frequently”, and “avoiding going out for fear of falling”. The third theme was “health-care lost”, which involved the following sub-themes: “silence as giving up on life”, “asthenia due to lack of appetite”, “painful body”, “many medications and poor health”, and “treatment that doesn't help”. The last theme was “something to depend on during COVID-19”, which consisted of the following sub-themes: “gratitude to care givers”, “longing for a bereaved family”, and “precarious place of residence”.Conclusion: Older women living alone experienced aggravated vulnerability and difficulty with health management due to a lack of social support during the COVID-19 period. This study suggests the need for a social safety network and vividly reveals the necessity of caregivers’ support and policy assistance for socially vulnerable populations.

A Before-and-After Study of a Collision Risk Detecting and Warning System on Local Roads

Local roads have numerous blind spots caused by complex geometry, obstacles, and narrow width. Thus, conventional proactive countermeasures, such as passive traffic signs and convex mirrors, have not always been effective in preventing local road collisions. In this paper, we present a novel proactive two-step approach for traffic safety on local roads, comprised of detection of pedestrian-to-vehicle and vehicle-to-vehicle collision risks and warning systems. First, using video surveillance and radars to eliminate blind spots, the system detects road objects, predicts their trajectories and reachable areas, and identifies a potential risk situation. Second, it provides road users such as vehicles and pedestrians with warnings through LED variable message signs, which allows them to react effectively in risky situations. We have applied the system to two local road sites in South Korea, including a university campus in Seoul City and an apartment complex in Daejeon City. The detecting system has been validated using a confusion matrix. We have assessed the warning effect through a before-and-after study and found that the proposed system contributed to the improvement of traffic safety at the case study site in that traffic conflicts decreased by 55–62%.

In search of Jong Ha Kim, the first Korean medical doctor in modern Daejeon city

Background: Recently, it was revealed that Jong-Ha Kim was the first self-employed Korean physician in Daejeon city of South Korea during the Japanese colonial period. However, little is known about him. In this paper, the author aimed to search for historical records of his activities as the first Korean physician in Daejeon city.Current Concepts: Kim’s clinic in Daejeon city was called Chung-Ang Clinic. This is all that has ever been confirmed about Jong-Ha Kim. The author has been searching for his medical record for the last year. Kim’s medical records were collected from journal papers on the modern history of Korea, National Institute of Korean History database, Naver news library archive, official gazette of the Japanese government-general of Korea, database of Seoul National University alumni, and a resume of a professor at the Hamhung Medical School. The results are as follows. He was born in Shinchang-ri Hamheung city Hamgyeongnam-do on August 9, 1900. He graduated from the missionary school established by Canadian missionaries and was admitted to Kyungseong (Keijo) Medical School in 1918. It was recently discovered that he participated in the Independence movement on March 1, 1919. His picture, an old leaflet for his clinic which he had used, and his resume as a professor at the Hamhung Medical School were discovered for the first time.Discussion and Conclusion: The historical records of Jong-Ha Kim’s life provide insight into the lives of contemporary doctors in modern Korea. During the period of 1900 to 1950, which encompasses his historical records, significant events took place in Korean history, and he actively participated in these events. Despite facing numerous difficulties as a doctor in modern Korea, Jong-Ha Kim made decisions that had a great impact. He was a great doctor who served as a good role model.

지역서점 활성화를 위한 도서캐시백 사업의 효과 분석

Daejeon city provides cash-back rewards to consumers when they purchase books by local currency, ‘Ontong Dajeon’. This study analyzes the policy effects of the Daejeon’s cash-back rewards program for local bookstores. By using individual bookstores’s data of credit card payments and local currency payments, we empirically analyze the effects of cash-back rewards on sales growth and redistribution of local bookstores. Main findings can be summarized as follows. First, our ‘Before-and-After’ analysis shows that sales of local bookstores were increased by an average 53% during consumers provided with the cash-back rewards. Second, mitigating effect of cash-back rewards on sales inequality among local bookstores is very small. Specifically, as the ratio of local currency payments to total payments increase by 1%, Gini coefficient of local bookstores’ sales decrease by only 0.0084%.

Flower pollination global peak search algorithm for partially shaded solar photovoltaic system

Photovoltaic (PV) systems are required to function at their maximum power point (MPP) to fully utilize solar energy. Solar PV panels are configured with maximum power point tracking (MPPT) systems to enhance the generation and supply of the maximum available power. However, owing to external environmental factors and partial shading conditions (PSCs), the tracking process becomes complex. Conventional MPPT methods cannot always achieve the global MPP. Thus, an advanced metaheuristic MPPT scheme for PV systems, the flower pollination algorithm (FPA), is implemented in this study to find the best global duty cycle to obtain the maximum power output, and a Levy flight is utilized to enhance FPA convergence. The FPA MPPT model was established, and its performance was compared with the conventional, and some meta-heuristic-based MPPT techniques; perturb and observe (PO), incremental conductance (INC), particle swarm optimization (PSO), cuckoo search (CS), grey wolf optimization (GWO), genetic algorithm (GA), double integral sliding mode control (DISMC), and hill-climbing (HC). Different scenarios were considered for the simulation: partial shading, complex partial shading, long-width, and long-length partial shading, and different temperature conditions employing series and series-parallel PV array configurations. In addition, real-world field atmospheric irradiance data for Daejeon city is used for the study. In terms of efficiency, the FPA attains at most 83%–96% of the expected GMP from the PV array as compared with the other MPPT techniques in all scenarios considered. The adopted FPA obtained the following root mean square error (RMSE), mean relative error (MRE), and mean absolute error (MAE) values respectively for each Scenario as follows: Scenario I: RMSE: 0.0061, MRE: 0.0463, MAE: 6.0745e-06, Scenario II: RMSE: 0.0116, MRE: 0.0430, MAE: 1.0738e-05, Scenario III: RMSE: 0.0640, MRE: 0.206, MAE: 4.8239e-05, Scenario IV (varying temperature conditions): RMSE: 0.0062–0.0074, MRE: 0.0460–0.0548, MAE: 6.1333e-06 – 7.4922e-06. A unique sensitivity performance comparison analysis is done employing the power spectral analysis to validate the effectiveness of the adopted FPA to the other MPPT techniques. The FPA performs better than all the techniques in all scenarios in comparing their maximum power tracked, convergence speed and accuracy, system efficiency, and optimum statistical results attained.

Prevalence of giardiasis of stray cats in the Daejeon city

Prevalence of giardiasis of stray cats in the Daejeon city

Error budget analysis of geocoding and geometric correction for KOMPSAT-5 SAR imagery

ABSTRACT Geocoding geometrically rectifies a remote sensing image according to a specific map projection, and is an essential process for utilizing synthetic aperture radar (SAR) satellite images. The accuracy of geocoding is affected by various intercorrelated error sources. In this study, we propose a framework for improving the geocoding accuracy of SAR images. Our framework consists of two major theoretical and computational steps: 1) calculating and setting the error budget of the SAR image geocoding accuracy and checking their quality and 2) applying a geometric correction model if the quality is lower than the predefined threshold. Error budget analysis was performed by utilizing the law of variance propagation, considering the correlations among the primary error sources. During the second (geometric correction) step, the non-multicollinearity (N-MC) model, a ground control point (GCP)-based geometric correction model without multicollinearity, was proposed. Experiments were conducted using two KOMPSAT-5 SAR images from Daejeon City, Korea to verify the framework. The geocoding accuracy of SAR images #1 and #2 exceeded the error budgets of all confidence levels, except for the row direction of SAR image #2, despite the vendor’s internal calibration. In the second step, two SAR images were geometrically corrected by applying the N-MC model. The use of geometric correction improved the geocoding accuracy of the two SAR images by approximately two to five pixels in the row and column directions. The final geocoding accuracy of the SAR images was within the error budget.

대전 원도심 소리풍경에 관한 의미론적 연구 - 대흥동 성당과 은행동 성심당 종소리를 중심으로 -

The purpose of this study is to illuminate the meaning of the soundscapes of two bells, Daeheung-dong Cathedral and Sungsimdang in Eunghang-dong, which are landmarks and attractions in the historic downtown of Daejeon. The study was conducted through field research and recordings, as well as literature studies of related documents and soundscape theory. Daejeon city was developed along with Daejeon Railway Station during the Japanese colonial period in the early 20th century. As the Chungnam Provincial Office moved to Daejeon, Daeheung-dong and Eunhang-dong in Jung-gu, located near Daejeon Station, developed significantly and formed the city centre. As major administrative agencies moved to Seo-gu in the 1990s, the downtown area of Daejeon was on a path of decline, and the decline accelerated with the development of Sejong city. Meanwhile, Daeheung-dong Cathedral and Sungsimdang, founded by refugees during the Korean War, firmly protected the historic downtown area of Daejeon, where the natives left. Daeheung-dong Cathedral, established during the Japanese colonial period, is a local landmark with a history of 100 years in 2019. Sungsimdang, which was created with the backdrop of the Korean War, is also a historical and cultural asset with a history of 60 years and a local landmark selected as the No. 1 tourist attraction in Daejeon. This research, which started from the sound of the bells of Daeheung-dong Cathedral, heard even in the neighboring residential areas, led to the discovery of the bells of Sungsimdang in Eunhang-dong, located across the street. In this paper, the bells of Daeheung-dong Cathedral and Eunhang-dong Sungsimdang have characteristics of soundmarks according to R. Murray Schafer’s soundscape sound category. Furthermore, this paper attempted to analyze the meaning of the two bells according to the relatively recent EU soundscape definition. These two bells are signal sounds at the surface level, but are the sound marks of the historic downtown area of Daejeon at the deep level. Although there are outward differences in size, scale, frequency, and famousness, these two bells share a meaning in terms of locality and good influence with the historicity and spatiality of a special relationship. The implication of this study is that the two places should be preserved as local historical and cultural assets not only as visual landmarks but also as sound marks in the urban regeneration or urban development of Jung-gu, Daejeon.

Examining the effects of vertical outdoor built environment characteristics on indoor light pollution

Indoor light pollution threatens human health. This study examined how built environment characteristics affect nighttime light levels in the bedrooms of urban areas. Indoor illuminances were monitored in the bedrooms of 28 participants in the city of Daejeon, Korea, between 2 a.m. and 4:30 a.m. over five days. Five built environment variables surrounding the bedrooms under study were assessed. Results illustrate that residential floor area on floors of influence (±3 floors from the bedroom under study) increased indoor illuminance, but residential floor area on all floors, including those vertically distant from the bedroom, did not. Tree canopy percentage reduced indoor illuminance, suggesting that tree canopies block artificial light at night emitted at ground level. Non-residential floor area and length of road lanes did not have significant effects, further suggesting that tree canopies protect urban residents on upper floors from light directed upwards from streets and commercial facilities at ground level. These findings indicate that vertical separation of residential areas is an effective measure to mitigate light pollution, especially in high-density urban areas where horizontal separation is not feasible. These findings also imply that policy efforts should focus on reducing light trespass from neighbors at similar heights.

Asset valuation methods for Road facilities: Focusing on Daejeon city

Asset valuation methods for Road facilities: Focusing on Daejeon city

Integrating multi-scale inspection, maintenance, rehabilitation, and reconstruction decisions into system-level pavement management systems

We are presenting a pavement management framework that involves multi-scale decisions, including system-level budget allocations, group-level inspections, and facility-level maintenance, rehabilitation, and reconstruction (MR&R) strategies. We consider two objectives: (i) to minimize the total discounted cost for the main stakeholders, represented by the agency and users; and (ii) to minimize the discounted user costs under a limited agency budget. Inspection technology innovations have enabled us to investigate the conditions of a group of multiple roadway facilities almost simultaneously, using instrumented vehicles that can travel at the same speed as traffic. Previous related studies have primarily focused on, at most, a bi-level structure with all the managerial activities, such as inspection and MR&R at the facility level and the allocation of a pooled budget at the system level. However, this cannot reflect the current group-level inspection practice, positioned between the facility and system levels. The proposed methodology adopts a bottom-up approach to account for heterogeneous facility- and group-specific properties, and it optimally facilitates determination of the multi-scale decisions to minimize the discounted societal costs. We address the complex multi-scale problem efficiently by adopting the Markov Decision Process, function approximation, and Lagrangian relaxation. As a numerical study, we analyze a real-world roadway network, including three expressway groups and one local road group, near Daejeon City in Korea. The system-level optimal solutions for the multi-scale decisions are determined, and the impacts of the grouping method are investigated.

도시형태와 건축물 특성이 원도심 에너지 효율에 미치는 영향 : 대전 및 제천 원도심의 비교 분석을 중심으로

Purpose: This study aims to identify the impacts of urban and building forms on the energy consumption of buildings. It applies microscopic elements such as urban forms, urban tissues, building forms, and building character as factors affecting the energy consumption of buildings. To this end, the 2018 energy consumption of the Old Downtowns of Daejeon City and Jaecheon City were analyzed. Methods: This study performs a log transformation of dependent variables in order to apply ordinary least squares (OLS), a method utilized in many studies focusing on the energy consumption of buildings. Results: The analysis results show that most but not all elements related to urban forms and tissues demonstrate a meaningful relationship to the energy consumption of buildings. As for urban form-related elements, buildings with high density and that are divided into numerous blocks show high energy consumption efficiency. Among the building-related elements, time-worn masonry buildings generally demonstrate a low energy consumption efficiency. It is also found that a difference in urban forms has an effect on the energy consumption of buildings, which confirms the fact that improvements in urban form should be accompanied with an endeavor to boost the energy efficiency of building units. These results are expected to contribute to the establishment of a foundation for more sustainable and resilient cities through the reduction of the energy consumption of buildings.