• International Journal of Contents
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• 제8권3호
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• pp.34-41
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• 2012

The concept of vegetation freeboard equivalence (VFE) is presented from the comparison between the rise in stage with/without vegetation and the freeboard height under design discharge conditions. In South Korea, the freeboard height of large, medium and small rivers is defined as a function of river discharge. Two models are used for this analysis of flood stage with and without vegetation: the 1-D model HEC-RAS and the 2-D model RMA-2. Both models are applied to three river study sites of the Geum River in South Korea as representative sites for a large, a medium and a small river. The analysis shows that without vegetation, both models provide comparable results and the calculated results are in very good agreement with the design configuration. The vegetation effects on the medium river are less significant, and the freeboard is adequate to contain the rise in stage from the added floodplain vegetation in large rivers. The concept of vegetation freeboard equivalence is therefore useful for the analysis of flood river stages after the restoration of channels with increased floodplain vegetation.

• Structural Engineering and Mechanics
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• 제45권5호
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• pp.595-611
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• 2013

This paper aims to compare three collocation point methods associated with the odd order stochastic response surface method (SRSM) in a systematical and quantitative way. The SRSM with the Hermite polynomial chaos is briefly introduced first. Then, three collocation point methods, namely the point method, the root method and the without origin method underlying the odd order SRSMs are highlighted. Three examples are presented to demonstrate the accuracy and efficiency of the three methods. The results indicate that the condition that the Hermite polynomial information matrix evaluated at the collocation points has a full rank should be satisfied to yield reliability results with a sufficient accuracy. The point method and the without origin method are much more efficient than the root method, especially for the reliability problems involving a large number of random variables or requiring complex finite element analysis. The without origin method can also produce sufficiently accurate reliability results in comparison with the point and root methods. Therefore, the origin often used as a collocation point is not absolutely necessary. The odd order SRSMs with the point method and the without origin method are recommended for the reliability analysis due to their computational accuracy and efficiency. The order of SRSM has a significant influence on the results associated with the three collocation point methods. For normal random variables, the SRSM with an order equaling or exceeding the order of a performance function can produce reliability results with a sufficient accuracy. The order of SRSM should significantly exceed the order of the performance function involving strongly non-normal random variables.

• 응용통계연구
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• 제24권2호
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• pp.315-321
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• 2011

Gene expression microarray data often include multiple missing values. Most gene expression analysis (including gene clustering analysis); however, require a complete data matric as an input. In ordinary clustering methods, just a single missing value makes one abandon the whole data of a gene even if the rest of data for that gene was intact. The quality of analysis may decrease seriously as the missing rate is increased. In the opposite aspect, the imputation of missing value may result in an artifact that reduces the reliability of the analysis. To clarify this contradiction in microarray clustering analysis, this paper compared the accuracy of clustering with and without imputation over several microarray data having different missing rates. This paper also tested the clustering efficiency of several imputation methods including our propose algorithm. The results showed it is worthwhile to check the clustering result in this alternative way without any imputed data for the imperfect microarray data.

• Journal of Acupuncture Research
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• 제19권3호
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• pp.138-155
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• 2002

Objective : The purpose of this study is to work on the problems and on the direction of the study regarding the evidence-based study of Acupuncture. Methods : We reviewed the PubMed electronic database. Eight articles of systematic review without meta-analysis and six articles without meta-analysis were selected. Results : In the study of eight articles of systematic review without meta-analysis, there were two articles on effectiveness of acupuncture and one on non-effectiveness of acupuncture. Four articles were about the changes according to the quality of randomized controlled trials. Also, one article was about the side-effect of acupuncture. In the study of six articles of systematic review with meta-analysis, there were two articles on Odds Ratio, two on Relative Risk, one on number-needed-to-treat, and two on 18 predefined methodological criteria. Conclusion : As the quality of RCTs was high, positive response decreased and as the quality of RCTs was low, positive response increased. For the study of evidence-based acupuncture, it is necessary that we conduct research on well-planned placebo acupuncture, large sample size, statistical method, method of searching and assessing literature and method of meta-analysis.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권3호
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• pp.478-491
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• 2013

Natural vibration analysis of plates with openings of different shape represents an important issue in naval architecture and ocean engineering applications. In this paper, a procedure for vibration analysis of plates with openings and arbitrary edge constraints is presented. It is based on the assumed mode method, where natural frequencies and modes are determined by solving an eigenvalue problem of a multi-degree-of-freedom system matrix equation derived by using Lagrange's equations of motion. The presented solution represents an extension of a procedure for natural vibration analysis of rectangular plates without openings, which has been recently presented in the literature. The effect of an opening is taken into account in an intuitive way, i.e. by subtracting its energy from the total plate energy without opening. Illustrative numerical examples include dynamic analysis of rectangular plates with rectangular, elliptic, circular as well as oval openings with various plate thicknesses and different combinations of boundary conditions. The results are compared with those obtained by the finite element method (FEM) as well as those available in the relevant literature, and very good agreement is achieved.

• Safety and Health at Work
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• 제2권4호
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• pp.321-327
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• 2011

Objectives: To find out from an analysis of empirical data the levels of influence, which a labor union (LU) and Occupational Safety and Health Committee (OSHC) have in reducing the occupational injury and illness rate (OIIR) through their accident prevention activities in manufacturing industries with five or more employees. Methods: The empirical data used in this study are the Occupational Safety and Health Tendency survey data, Occupational Accident Compensation data and labor productivity and sales data for the years 2003 to 2007. By matching these three sources of data, a final data set (n = 280) was developed and analyzed using SPSS version 18 (SPSS Inc., Chicago, IL, USA). Results: It was found that a workplace with a LU has a lower OIIR than one without a LU. In manufacturing industries with five or more employees in 2007, the OIIR of the workplaces without a LU was 0.87%, while that of workplaces with a LU was much lower at 0.45%. In addition, workplaces with an established OSHC had a lower OIIR than those without an OSHC. Conclusion: It was found that the OIIR of workplaces with a LU is lower than those without a LU. Moreover, those with the OSHC usually had a lower OIIR than those without. The workplace OIIR may have an impact on management performance because the rate is negatively correlated with labor productivity and sales. In the long run, the OIIR of workplaces will be reduced when workers and employers join forces and recognize that the safety and health activities of the workplace are necessary, not only for securing the health rights of the workers, but also for raising labor productivity.

• Steel and Composite Structures
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• 제17권4호
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• pp.405-429
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• 2014

In this paper, it is aimed to determine the structural behavior of suspension bridges considering construction stages and different soil conditions. Bosporus Suspension Bridge connecting the Europe and Asia in Istanbul is selected as an example. Finite element model of the bridge is constituted using SAP2000 program considering existing drawings. Geometric nonlinearities are taken into consideration in the analysis using P-Delta large displacement criterion. The time dependent material strength of steel and concrete and geometric variations is included in the analysis. Time dependent material properties are considered as compressive strength, aging, shrinkage and creep for concrete, and relaxation for steel. To emphases the soil condition effect on the structural behavior of suspension bridges, each of hard, medium and soft soils are considered in the analysis. The structural behavior of the bridge at different construction stages and different soil conditions has been examined. Two different finite element analyses with and without construction stages are carried out and results are compared with each other. At the end of the analyses, variation of the displacement and internal forces such as bending moment, axial forces and shear forces for bridge deck and towers are given in detail. Also, displacement and stresses for bridge foundation are given with detail. It can be seen from the analyses that there are some differences between both analyses (with and without construction stages) and the results obtained from the construction stages are bigger. It can be stated that the analysis without construction stages cannot give the reliable solutions. In addition, soil condition have effect on the structural behavior of the bridge. So, it is thought that construction stage analysis using time dependent material properties, geometric nonlinearity and soil conditions effects should be considered in order to obtain more realistic structural behavior of suspension bridges.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.592-597
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• 1996

The KALIMER core, of which nuclear design is largely governed by inherent safety and reactivity control issues, is fueled with metallic fuel, and the initial core will be loaded with 20% enriched Uranium metal fuel. KALIMER safety design objectives include the accommodation of unprotected, ATWS events without operator action, and without the support of active shutdown, shutdown heat removal, or any automatic system without damage to the plant and without jeopardizing public safety. The transient analysis of the core designs has been focused on severe events to assess the margins in the design, and ATWS events are the most severe events that must be accommodated by the KALIMER design. The ATWS performance has been evaluated for the preliminary initial core design of KALIMER with a particular emphasis on the inherent negative reactivity feedback effects, including the Doppler, sodium density, fuel axial expansion, core radial expansion, and control rod driveline expansion. Results show that the Uranium metal core design meets the temperature limits with margin.

• 한국지리정보학회지
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• 제13권2호
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• pp.119-132
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• 2010

본 연구에서는 울산광역시 태화강 유역에 대하여 건물영향을 고려한 2차원 침수해석을 실시하여 건물영향에 따른 흐름의 양상, 침수심, 침수위 등을 분석하였다. 지형자료는 최근 대도시를 중심으로 구축되고 있는 1m 간격으로 수집된 LiDAR 자료를 바탕으로 10m 간격의 자료를 추출하여 지형자료를 생성하였으며, 수치지형도로부터 추출된 건물자료를 GIS Tool을 활용하여 구축된 지형자료와 합성하여 2차원 침수해석에 적용되는 지형자료를 구성하였다. 파제에 대한 가상의 시나리오를 생성하여 건물영향을 고려한 2차원 침수해석을 실시하였으며, 침수해석 결과에 대한 분석을 통하여 효율적이고 정확한 침수해석 방법을 제안하고자 하였다. 침수면적에 따른 적합도는 건물영향을 고려한 경우와 고려하지 않은 경우를 비교한 결과 90%이하로 떨어지는 것을 확인하였고, 최대 침수심은 건물영향을 고려하지 않은 경우가 건물영향을 고려한 침수해석 결과보다 0.29m 높게 계산되는 것으로 나타났으며, 침수위의 경우 침수심과는 반대로 건물영향을 고려한 경우의 침수해석 결과가 0.49m 높게 나타나는 것으로 분석되었다.

• 한국해양공학회지
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• 제30권2호
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• pp.84-90
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• 2016

In this study, a six degree-of-freedom motion analysis of a wind-wave hybrid platform equipped with numerous wave energy converters (WECs) was carried out. To examine the effect of the WECs on the platform, an analysis of one-way coupling was carried out, which only considered the power take-off (PTO) damping of the static WECs on the platform. The equation of motion of a floating platform with mooring lines in the time domain was established, and the responses of the one-way coupled platform were then compared with the case of a platform without any coupling effects from the WECs. The hydrodynamic coefficients and wave exciting forces were obtained from the 3D diffraction/radiation pre-processor code WAMIT based on the boundary element method. Then, an analysis of the dynamic responses of the floating platform with or without the WEC effect in the time domain was carried out. All of the dynamics of a floating platform with multiple wind turbines were obtained by coupling FAST and CHARM3D in the time domain, which was further extended to include additional coupled dynamics for multiple turbines. The analysis showed that the PTO damping effect on platform motions was negligible, but coupled effects between multiple WECs and the platform may differentiate the heave, roll, and pitch platform motions from the one without any effects induced by WECs.