Measured Research Articles

Development of suspended solid concentration measurement technique based on multi-spectral satellite imagery in Nakdong River using machine learning model

Development of suspended solid concentration measurement technique based on multi-spectral satellite imagery in Nakdong River using machine learning model

Three-dimensional vibration measurement method for lightweight beam based on machine vision

Three-dimensional vibration measurement method for lightweight beam based on machine vision

Guideline on optimal blood pressure range for Chinese oldest old

Hypertension is a major problem of public health that endangers the health of the oldest old. However, the current guidelines for hypertension management do not uniformly diagnose hypertension among the oldest old, nor recommend a normal blood pressure range, which is not convictive enough to support the decision making to the prevention of blood pressure-related adverse events. This guideline gives guiding opinions on optimal blood pressure range for the Chinese oldest old, which applies to the staff of medical and health institutions at all levels nationwide to evaluate the blood pressure levels of the oldest old. It includes the sections of general principles, methods and standards of blood pressure evaluation, measurement conditions, specifications of blood pressure measurement, implementation approaches, etc. The guideline has important directive significance for improving the blood pressure management and decision-making level of the Chinese oldest old.

Experimental study on magnet support plinths of advanced light source

As the installation foundation of magnet support, the plinth is critical for the stability of the whole support unit. Different fabrication and installation processes of plinths make significant differences in performance of the support unit. Based on the stringent requirements of advanced synchrotron light source for the mechanical stability of magnets, the plinth installation pouring experiment was carried out. Several concrete construction techniques commonly applied in practice were tested with the plinths of uniform shape and size. The natural frequency of each plinth was measured by hammering method and its stability was evaluated. It is concluded from the test result that secondary grouting can effectively improve the stability of the plinth and the plinth of epoxy-based grouting shows better performance in stability than that of cement-based grouting. Based on the natural frequency test result, the influence of the plinth installation on the system mode is analyzed with the support system of High Energy Photon Source as an example. The experimental results have certain reference value for the plinth design of similar machines.

Design of compact wideband Rotman lens for 5G multibeam application

In this paper, a compact broadband Rotman lens beamforming network based on equal optical path difference is proposed. The beamforming network is intended for applications in a multi-beam antenna array of 5G millimeter-wave (mm-wave) communication. Firstly, the theoretical design of the Rotman lens is introduced in detail. A power divider is used to replace the standard single-port feeding mode to generate a high-directional beam, reducing the scattering of the lens’ internal energy and the energy loss at adjacent ports. The Chebyshev multi-stub matching converter is used to optimize the original tapered array output port. To ensure a wide frequency band, the original matching port size is reduced, and the overall size of the lens is reduced by 20%. Measurement results of the improved model, show that the working frequency band of the lens is 16.5−33.8 GHz, of which S11 is better than 15 dB at 17.2−32.0 GHz, and the scanning angle is ±30°. The lens has a simple and compact structure, can effectively provide a stable phase difference signal for adjacent array elements, and achieve the goal of 5G millimeter-wave array multi-beam.

Ergonomic Study of VDT Workstations for Wheelchair Users

ABSTRACT This study presents a three-dimensional computer-modelling system based on Transom JACK software, with 3D objects/equipment and human subjects with specific anthropometric measurements to visualize and evaluate human-machine interaction. A computer simulation method is then adopted to evaluate some VDT (Visual Display Terminal) workstations to determine whether they are appropriate for use by wheelchair users. The study indicates that currently available commercial computer desks present difficulties, in terms of both spatial design and reachability of peripheral devices, to wheelchair users. Some VDT tasks result in awkward body postures in virtual subjects. New VDT workstations are designed and recommended to solve the shortcomings found.

Computer vision-based displacement measurement with m-sequence target

The development of image sensors enables the application of vision-based techniques to the non-contact displacement measurement of large-scale structures. The features of the physical targets are critical to the accuracy, stability and anti-interference of the displacement measurement results. In this study, a novel m-sequence target and the associated circular correlation processing technique are developed for real-time displacement measurement. The properties of the m-sequence as a pseudo-random sequence are introduced. The vision-based displacement calculation method is then derived from the correlation property of the m-sequence. The algorithms and measurement systems are integrated in the LabVIEW environment. To verify the anti-interference performance of the developed system, static and dynamic experimental tests are carried out with various forms of interference, such as partial occlusion, uneven illumination, out of focus and smoke effect. Experimental results indicate that the developed system cannot only accurately measure structural displacement, but also has outstanding antiinterference performance, even if 30% of the target is masked.

Prediction of scour around single vertical piers with different cross-section shapes

In the present work, a 3D numerical model is proposed to study local scouring around single vertical piers with different cross-section shapes under steady-current flow. The model solves the flow field and sediment transport processes using a coupled approach. The flow field is obtained by solving the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations in combination with the k-w SST turbulence closure model and the sediment transport is considered using both bedload and suspended load models. The proposed model is validated against the empirical measurements of local scour around single vertical piers with circular, square, and diamond cross-section shapes obtained from the literature. The measurement of scour depth in equilibrium condition for the simulations reveal the differences of 4.6%, 6.7% and 13.1% from the experimental measurements for the circular, square, and diamond pier cases, respectively. The model displayed a remarkable performance in the prediction of scour around circular and square piers where horseshoe vortices (HSVs) have a leading impact on scour progression. On the other hand, the maximum deviation was found in the case of the diamond pier where HSVs are weak and have minimum impact on the formation of local scour. Overall, the results confirm that the prediction capability of the present model is almost independent of the strength of the formed HSVs and pier cross-section shapes.

Experimental and numerical investigation of a surface-fixed horizontal porous wave barrier

Experimental and numerical investigations were conducted to study the performance of a surface-fixed horizontal porous wave barrier in regular waves. The characteristics of the reflection and transmission coefficients, energy dissipation, and vertical wave force were examined versus different porosities of the barrier. Numerical simulations based on 3D Reynolds Averaged Navier-Stokes equations with standard low-Re k-e turbulent closure and volume of fluid approach were accomplished and compared with the experimental results conducted in a 2D wave tank. Experimental measurements and numerical simulations were shown to be in satisfactory agreement. The qualitative wave behavior propagating over a horizontal porous barrier such as wave run-up, wave breaking, air entrapment, jet flow, and vortex generation was reproduced by CFD computation. Through the discrete harmonic decomposition of the vertical wave force on a wave barrier, the nonlinear characteristics were revealed quantitatively. It was concluded that the surface-fixed horizontal barrier is more effective in dissipating wave energy in the short wave period region and more energy conversion was observed from the first harmonic to higher harmonics with the increase of porosity. The present numerical approach will provide a predictive tool for an accurate and efficient design of the surface-fixed horizontal porous wave barrier.

Effect of Ice accretion on the aerodynamic characteristics of wind turbine blades

Cold regions with high air density and wind speed attract wind energy producers across the globe exhibiting its potential for wind exploitation. However, exposure of wind turbine blades to such cold conditions bring about devastating impacts like aerodynamic degradation, production loss and blade failures etc. A series of wind tunnel tests were performed to investigate the effect of icing on the aerodynamic properties of wind turbine blades. A baseline clean wing configuration along with four different ice accretion geometries were considered in this study. Aerodynamic force coefficients were obtained from the surface pressure measurements made over the test model using MPS4264 Simultaneous pressure scanner. 3D printed Ice templates featuring different ice geometries based on Icing Research Tunnel data is utilized. Aerodynamic characteristics of both the clean wing configuration and Ice accreted geometries were analysed over a wide range of angles of attack (α) ranging from 0° to 24° with an increment of 3° for three different Reynolds number in the order of 105. Results show a decrease in aerodynamic characteristics of the iced aerofoil when compared against the baseline clean wing configuration. The key flow field features such as point of separation, reattachment and formation of Laminar Separation Bubble (LSB) for different icing geometries and its influence on the aerodynamic characteristics are addressed. Additionally, attempts were made to understand the influence of Reynolds number on the iced-aerofoil aerodynamics.

An Enhanced Differential Private Protection Method Based on Adaptive Iterative Wiener Filtering in Discrete Time Series

Although many proposed researches on differential privacy protection in correlation time series have made great progress, there are still some problems. Because different methods are based on different models and rules. There is no uniform attack model, their privacy protection intensity cannot be compared and measured horizontally. This paper designs an attack model for the differential privacy in correlation time series based on adaptive iterative wiener filtering. Experimental results show that the attack model is effective and provides an uniform measurement for the privacy protection with different methods.

Prediction of the effects of environmental factors towards novel corona virus (COVID-19) outbreak using AI-based models

The need for elucidating the effects of environmental factors in the determination of the novel corona virus (COVID-19) is very vital. This study is a methodological study to compare three different test models (1. Artificial neural networks (ANN), 2. Adaptive neuro fuzzy inference system (ANFIS), 3. A linear classical model (MLR)) used to determine the relationship between COVID19 spread and environmental factors (temperature, humidity, wind etc.). Three different models were used including two artificial intelligence (AI) based models (artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS)) and a linear regression model (multilinear regression analysis (MLR). These data were obtained from the studies (Pirouz, Haghshenas, Haghshenas, & Piro, 2020) with confirmed COVID-19 patients in Wuhan, China, using temperature, humidity and wind as the independent variables. The measured and the predicted results were checked based on three different performance indices; Root mean square error (RMSE), determination coefficient (R 2 ) and correlation coefficient (R). The results showed that ANFIS and ANN are more promising over the classical MLR models having an average R-values of 0.90 in both calibration and verification stages. The findings indicated that ANFIS outperformed MLR and ANN. In addition, their performance skills boosted up to 25% and 9% respectively based on the determination coefficient for the prediction of confirmed COVID-19 cases in Wuhan city of China. Overall, the results depict the reliability and ability of AI-based models (ANFIS and ANN) for the simulation of COVID-19 using the effects of various environmental variables.

경영학 융복합 역량 진단 지표 개발에 관한 연구

[연구목적] 본 연구는 4차 산업혁명 시대에 경영학 교육이 지향하는 융복합 인재 교육의 필요성에 주목하여, 경영학에 특화된 융복합 역량(Business Confluence Competency)을 개념화하고, 이를 측정하기 위한 진단 지표를 개발한 연구이다.<BR>[연구방법] 융복합 역량의 중요한 이론적 틀인 메타인지이론을 기반으로 하되, 경영학이 탐구하는 기업 장면의 특수한 맥락을 고려하여 경영학 융복합 역량 모델(KTA 모델)을 경영학 분야 최초로 개발하였다. KTA 모델은 경영학 기초 인지력(K; Knowing), 융합사고력(T; Thinking), 융합실행력(A; Acting)의 세 가지 하위 역량과 25개의 세부 측정 항목으로 구성되었다. 측정 도구로서의 유의성을 검증하기 위해 타당도와 신뢰도 검증을 실시하였다.<BR>[연구결과] 분석 결과 본 연구에서 개발한 경영학 융복합 역량 진단 지표는 높은 신뢰도와 더불어 내용/구성/예측 타당도가 검증되었다.<BR>[연구의 시사점] 본 연구에서 소개하는 KTA 모델은 경영학 융복합 인재 교육의 정책 수립, 과정 및 교육 내용 설계, 학습 수행 도구, 성과 평가 및 경영교육 인증 등의 다방면에서 높은 활용가치가 있을 것으로 기대한다.

MAGIC-f gel dosimeter reading: a comparison between an in-house optical CT and MRI imaging

Introduction: According to new developments in radiation therapy techniques, accurate ‎dose verification in three-dimensions has become more critical. Polymer gel dosimeters ‎‎(PGDs) are valuable tools to be used for this purpose. Nowadays, various imaging ‎modalities are employed to read out the gels. This study was aimed to investigate the ‎measured dose distribution recorded in MAGIC-f PGD with optical computed tomography ‎‎(OCT) by comparison with MRI. ‎Material and methods: We developed an in-house CCD based cone-beam OCT scanner. A ‎phantom of MAGIC-f PGD was used to measure a four-field box dose distribution. MRI and ‎OCT scanners were performed for gel readouts. Both measurement results were compared ‎by gamma index analysis with various acceptance criteria. The temporal stability of the gel ‎was also evaluated with the OCT readout system.‎Results: The percentage of isodose lines from two measured datasets agreed well together. ‎The pass rates were 99.02%, 96.8%, and 89.8% with 5%/5mm, 4%/4mm, and 3%/3mm ‎criteria, respectively, at the phantom's central axial slice. ‎Conclusion: The results indicate that the performance of this OCT system is almost the ‎same with acceptable discrepancies to the MRI as accepted standard readout modality, and ‎it can be used for three-dimensional dose verifications.‎

Effects of Disinfection on Orthodontic Plaster Models

Background and aims: The purpose of this study was to evaluate the effects of disinfection and different brands of alginate impression material on the accuracy of orthodontic stone models. Materials and methods: Six different alginate impression materials and four different disinfectants were included in the study. A total of 168 impressions were taken and divided into 24 groups. Fifty-six impressions taken with extended pour-type alginates were kept in sealed plastic bags for four days and then poured. One hundred and twelve impressions were poured immediately after the disinfection process. A 3-D laser scanner was used for dimensional measurements on the vestibule surface area, while the mesial–distal width of the right upper molar was measured with screen caliper software. Results: This study showed that the contraction of models varied significantly depending on the alginate material and disinfectant. Evaluation of the upper first molar showed that molar contraction varied between 1.2 and 3.2% in dimension. According to molar data, the best accuracy was obtained from Blueprint-Zeta, while the worst was obtained from the Hydrogum Ext Pour–NaOCl alginate– disinfectant combination. Two-way ANOVA of data from the vestibule surface area showed significant results for all pairwise comparisons of alginate and disinfectant materials and their interactions. According to the results of the two-way ANOVA, the best accuracy was obtained from Hydrogum and Blueprint alginates with Unident disinfectant. The worst accuracy was obtained from Hydrogum Ext Pour alginate with Zeta disinfectant. Conclusions: The dimensions of stone models produced from disinfectant-treated alginate impression materials demonstrate various degrees of contraction.

Preliminary Study on GIS Mapping-based Fine Dust Measurement in Complex Construction Site

Preliminary Study on GIS Mapping-based Fine Dust Measurement in Complex Construction Site

Turbine Efficiency Measurement of Pulsating Flow in a Twin Scroll Turbocharger

Turbine Efficiency Measurement of Pulsating Flow in a Twin Scroll Turbocharger

Development of Tilt angle measurement system of plastic thin-film using Position Sensitive Device

Development of Tilt angle measurement system of plastic thin-film using Position Sensitive Device

Quantitative risk assessment for wellbore stability analysis using different failure criteria

Uncertainties in geomechanical input parameters which mainly related to inappropriate data acquisition and estimation due to lack of sufficient calibration information, have led wellbore instability not yet to be fully understood or addressed. This paper demonstrates a workflow of employing Quantitative Risk Assessment technique, considering these uncertainties in terms of rock properties, pore pressure and in-situ stresses to makes it possible to survey not just the likelihood of accomplishing a desired level of wellbore stability at a specific mud pressure, but also the influence of the uncertainty in each input parameter on the wellbore stability. This probabilistic methodology in conjunction with Monte Carlo numerical modeling techniques was applied to a case study of a well. The response surfaces analysis provides a measure of the effects of uncertainties in each input parameter on the predicted mud pressure from three widely used failure criteria, thereby provides a key measurement for data acquisition in the future wells to reduce the uncertainty. The results pointed out that the mud pressure is tremendously sensitive to UCS and SHmax which emphasize the significance of reliable determinations of these two parameters for safe drilling. On the other hand, the predicted safe mud window from Mogi-Coulomb is the widest while the Hoek–Brown is the narrowest and comparing the anticipated collapse failures from the failure criteria and breakouts observations from caliper data, indicates that Hoek-Brown overestimate the minimum mud weight to avoid breakouts while Mogi–Coulomb criterion give better forecast according to real observations.

Using a printed grid for easy dermoscopy measurements.

Using a printed grid for easy dermoscopy measurements.