• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.395-395
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• 2019

대한민국에서 홍수는 매해 여름 발생하는 자연재해로 인명, 재산, 사회 기반시설에 심각한 피해를 일으키고 있으며, 기후변화로 인해 홍수 사상이 과거와는 다른 형태이다. 이를 대비하기 위해서는 기후변화를 고려한 홍수 위험도(flood risk)를 평가를 통해 적절한 대비책을 수립하여야 한다. 이에 본 연구는 전국의 홍수위험도를 중권역 별로 평가하는 홍수위험지수(Flood Risk Index, FRI)를 새로이 개발하였다. FRI는 세 가지 세부 지표인 위협도, 노출도, 대응능력(Hazard, Exposure, Capacity)의 결합으로 산정된다. 위협도는 직접적인 홍수의 원인이 되는 기상학적 요인인 강수에 대한 정보이고, 노출도는 홍수로부터 피해를 입을 수 있는 인명 및 재산에 대한 요소이다. 대응능력은 자연 환경과 인간의 중장기 전략을 고려한 적응능력(adaptive capacity)과 홍수 발생 시 조치능력(coping capacity)으로 나눠져 평가된다. 즉 위협도와 노출도가 높을수록 홍수 위험도가 커지며, 대응능력이 뛰어날수록 홍수 위험도는 줄어든다. 인자들은 특정 유형의 위험도에만 초점이 맞춰지지 않고 다양한 방면을 포괄적으로 평가할 수 있도록 선정되었으며, 통계 기법을 활용해 FRI를 산정하였다. 크론바흐 알파 계수(Cronbach's ${\alpha}$)를 통해 FRI의 타당성을 진단하였으며, 홍수피해금액간의 스피어만(Spearman) 상관계수를 통해 FRI의 설명력을 검증해 신뢰도를 제고했다. 최종적으로 환경부로부터 제공받은 미래 기후 시나리오를 사용하여 FRI를 산출해 미래의 세 시점(2030년대, 2050년대, 2080년대)의 전국 홍수위험도 평가를 진행하였다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.179-188
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• 2015

This study reviewed the type of the project and developmental plan related to ocean energy development in the coastal land boundaries and the ocean, and suggested the efficient scoping method through the diagnosis of the key items of environmental impact assessment (EIA) in the coastal area. The major projects are the construction of tidal power plant, tidal current power plant, and offshore wind power plant in the public water, and also those are the construction of solar power plants in the coastal land boundaries. While the project plans on a large scale such as the construction of tidal power plant, it is important to consider both property of usefulness of the designated areas and harmony analysis with marine space availability based on the adequacy of the site selection and relevance of plan with the master plan for reclamation and strategic environmental assessment (SEA). And also it needs to be considered the careful checkup on the EIA checklist referring to the type of project, effective post-monitoring, and suggestion of mitigating methods to minimize the environmental impacts during the stage of actual environmental impact assessment. Introduction of a system of integrated marine environmental impact assessment should be considered for reasonable and effective manage to developmental projects on the marine spatial area.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.01a
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• pp.331-334
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• 2016

본 연구에서는 표준 게이트웨이 기반의 다중 생체계측 장비 및 CMCIS(Central Monitoring and Cardiology Information System) 기반의 통합 시스템을 개발하기 위한 타당성 분석을 위한 국내외 동향을 분석한 연구이다. 개발의 필요성을 타진하기 위하여 기술, 사회, 경제적 중요성과 국내외 관련기술의 현황을 분석하였다. 분석한 결과, 대부분 해외의 다국적 기업에 의존하는 실정이며 심혈관계 질환의 지속적 증가로 효율적인 의료 서비스를 위한 기술개발의 필요성이 높게 평가되었다. 또한 표준 게이트웨이 기술의 확보로 진단용 심전계 표준 게이트웨이를 적용함으로써 다양한 HIS 인터페이스가 가능하며, 편의성이 증대되어 활용성이 높아질 것으로 예상된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.93-100
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• 2014

Steel reinforcement buried in concrete structure in submerged zone does not easily become corroded due to lack of dissolved oxygen. For that reason, accelerated corrosion test in submerged state is performed with an electrochemical method, which is not suitable for actual corrosion mechanism and makes it difficult to find relevance with long-term behavior. In this study, accelerated corrosion test was performed with the temperature and chloride concentration as main variables in order to establish a method for accelerated corrosion test in submerged zone. Corrosion was determined by the result of reinforcement corrosion monitoring based on galvanic potential measurement and half-cell potential method. The accelerated corrosion test result showed that temperature had the most dominant influence. To determine the chloride content, chloride concentration by depth in the test sample was measured. With the same conditions, chloride penetration interpretation was performed by DuCOM, a FEM durability interpretation program. Also, a test was performed to measure dissolved oxygen according to soaking conditions of artificial seawater, which was used for verifying the validity of the accelerated corrosion test result.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.60-68
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• 2012

This study describes an analytical and experimental investigation of the pedestrian steel-deck truss bridge in the City of Rochester, New York, U.S.A. This investigation was undertaken to provide assurance that this important bridge continues to be functional for this use. An ambient vibration experiment on full-scale structures is a way of assessing the reliability of the various assumptions employed in the mathematical models used in analysis. It is also the most reliable way of determining the structural parameters of major importance in structural dynamics, such as the mode shapes and the associated natural frequencies. Pedestrian-induced vibrations have been measured on the bridge to determine the displacement and the vertical and transverse dynamic characteristics of the steel deck truss. In the analytical modeling, three-dimensional finite element analysis was developed and validated against the ambient tests.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.4
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• pp.171-178
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• 2019

The use of anti-scatter grids in radiographic imaging has the advantage of preventing the image distortion caused by scattered radiation. However, it carries the side effect of leaving artifacts in the X-ray image. In this paper, we propose a grid line suppression technique using discrete cosine transform(DCT). In X-ray images, the grid lines have different characteristics depending on the shape of the object and the area of the image. To solve this problem, we adopt the DCT transform based on a dynamic segmentation, and propose a filter transfer function for each individual segment. An algorithm for detecting the band of grid lines in frequency domain and a band stop filter(BSF) with a filter transfer function of a combination of Kaiser window and Butterworth filter have been proposed. To solve the blocking effects, we present a method to determine the pixel values using multiple structured images. The validity of the proposed theory has been evaluated from the experimental results using 140 X-ray images.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.5 s.57
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• pp.109-120
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• 2009

This paper introduces a new method to estimate the loss of prestressing force for the externally prestressing tendon. The proposed method that combines of HGA and FEM is able to identify the lost tensile force of a externally prestressed tendon. The identification variables of the proposed method is a exteranlly prestressed tendon of tension, effective nominal diameter, mass per unit length and Rayleigh damping coefficients. First of all, a finite element model system is constructed to consider the effect of damping, and these variables are identified using inverse analysis technique - updating algorithm. Finally, throughout total 3 cases of numerical tests, the numerical propriety of the proposed method is verified. Here, it is seen that the errors in the estimated variables by the proposed method are about 1% except in the case of Rayleigh damping coefficients.

• Journal of Life Science
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• v.20 no.1
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• pp.9-16
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• 2010

This study investigated cut-off values of body mass index (BMI) and body fat measures for metabolic syndrome (MS) in elderly Koreas. Questionnaire surveys, anthropometric measurements, medical examinations, and body composition analyses were conducted for 10,077 subjects aged 40-65 years in the health examinee cohort in Korea between 2004 and 2006. Cut-off values were identified using receiver-operating characteristic (ROC) curve analysis for both men and women. Stratified analyses by weight range (<60, 60-69, 70-79, and 80-89, ${\geq}90\;kg$ for men; <50, 50-59, 60-69, 70-79, ${\geq}80\;kg$ for women) were conducted. Among male subjects, the cut-off points were $25.5\;kg/m^2$ for BMI with a sensitivity of 70.0% and a specificity of 72.0%, and 26.1% for body fat percentage with a sensitivity of 60.6% and a specificity of 76.4%. Among female subjects, the cutoff points were $24.1\;kg/m^2$ for BMI with a sensitivity of 73.3% and a specificity of 68.8%, and 31.5% for body fat percentage with a sensitivity of 76.7% and a specificity of 65.6%. Stratified analysis by weight range showed that the cutoff points of BMI and body fat measures tended to higher as weight level increased. The results of our study suggest cut-off values of BMI and body fat measure for MS were similar to the general obesity criteria in Korea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.576-582
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• 2018

At present, universities in Korea are trying to raise the competency of university students by preparing them with abilities and attitudes required in society, and many universities are carrying out "core competency based education." Therefore, there is a need to evaluate the core competencies of students and verify educational performance. M University, which trains students in specialized marine topics, also conducts core competency based education, reflecting the specificity of the university. The purpose of this study was to develop and validate a tool to measure the core competencies of M University students. First, preliminary questions were developed based on a literature review. Second, item analysis and exploratory factor analysis were conducted. As a result, six factors were identified. Finally, a total of 50 items were extracted from the final test, and validity was confirmed. The scale developed on the basis of this study can not only diagnose the core competency of students overall but also connect programs by diagnosing individual core competencies. It will be possible to use these results as basic data for honing the differentiated talents of universities specialized in maritime and ocean-related topics.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.3
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• pp.212-216
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• 2011

Fault detection technique for photovoltaic power systems is significant to dramatically reduce economic damage in industrial fields. This paper presents a novel fault detection approach using Fourier neural networks and stochastic decision making strategy for photovoltaic systems. We achieve neural modeling to represent its nonlinear dynamic behaviors through a gradient descent based learning algorithm. Next, a general likelihood ratio test (GLRT) is derived for constructing a decision malling mechanism in stochastic fault detection. A testbed of photovoltaic power systems is established to conduct real-time experiments in which the DC power line communication (DPLC) technique is employed to transfer data sets measured from the photovoltaic panels to PC systems. We demonstrate our proposed fault detection methodology is reliable and practicable over this real-time experiment.