• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1248-1253
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• 2007

Urban transit or subway stations generally service for a long period of several decades. And, the urban transit or subway is public transportation which lots of people takes every day. During the service time, they are inevitably damaged from environmental corrosion, material aging, fatigue, and the coupling effects with long-term loads and extreme loads. The included damage accumulates and performance degenerates due to the above factors. They would inevitably reduce the resisting capacity of station against the disaster; even they result in collapse with the structural failure under extreme loads. And, if disaster such as earthquake, fire, etc. happens, it causes huge property damage and threatens the human lives. Because of these above reasons, the intelligent health surveillance system should be researched and developed for ensuring the safety of station. In this paper, the research plans of the intelligent health surveillance system of urban transit station are presented. And also, the development or establishment directions of this system are suggested.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.231-234
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• 1997

This paper presents improved direct method for calculating the closest saddle node bifurcation (CSNB) point, which is also applicable to the selection of appropriate load shedding, reactive power compensation point detection. The proposed method reduced dimension of nonlinear equation compared with that of Dobson's direct method. The improved direct method, utilizing Newton Iterative method converges very quickly. But it diverges if the initial guess is not very close to CSNB. So the direct method is performed with the initial values obtained by carrying out the iterative method twice, which is considered most efficient at this time. Since sparsity techniques can be employed, this method is a good choice to a large scale system on-line application. Proposed method has been tested for 5-bus, New England 30-bus system.

• Steel and Composite Structures
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• 제7권2호
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• pp.105-118
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• 2007

On September $11^{th}$ 2001, the twin towers of the World Trade Center in New York City were struck by two hijacked airplanes. Despite severe local damage induced by the impact, the towers were able to sustain 102 and 56 minutes of the subsequent multi-storey fires before collapsing. The purpose of this study is to contribute to the understanding of the in-fire performance of composite trusses by examining the behaviour of the longer-span type used in the towers. It makes no attempt to be a forensic study of the actual events. Using the finite element package Vulcan, the structural mechanics of typical long-span composite floor trusses are explained, under a variety of scenarios, as the fire temperatures rise. Different boundary conditions, degrees of protection and loading are all covered, the results being presented mainly in the form of graphs of deflection and internal force of members against time.

• Computers and Concrete
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• 제18권6호
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• pp.1097-1112
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• 2016

Fire loading causes a critical collapse of RC (Reinforced Concrete) Structures since the embedded steels inside are relative week against high elevated temperature. Several numerical frameworks for fire resistance have been proposed, however they have limitations such as unstable convergence and long calculation period. In the work, 2-D nonlinear FE technique is proposed using Galerkin method for RC structures under fire loading. Closed-form element stiffness with a triangular element is adopted and verified with fire test on three RC slabs with different fire loading conditions. Several simulations are also performed considering fire loading conditions, water contents, and cover depth. The proposed numerical technique can handle time-dependent fire loading, convection, radiation, and material properties. The proposed technique can be improved through early-aged concrete behavior like moisture transport which varies with external temperature.

• 복합신소재구조학회 논문집
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• 제3권3호
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• pp.31-37
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• 2012

Under the huge seismic loads, there are too many risks about which high-rise buildings lost their lateral stiffness caused by plasticity on frame members. Because of earthquake is important cause to bring the collapes countinue to human's life, many reports examined these phenomenons in various angles. And some of them reported the high possibility about building collapse by deformation concentrations under huge earthquakes. For preventing these phenomenons, researchers suggest some items-such as adding damping devices or strengthen their ductility or stifness. This report suggests choose the method of strengthen building stiffness and suggests the alternative designs using high strength steel-SM570TMC, and provides the results of time-history analysis about the alternative designs for investigation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.939-944
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• 2003

The analysis involves an adaptive grid that is created under a criterion of element categorization of filling states and locations in the total region at each time step. By using an adaptive grid wherein the elements, finer than those in internal and external regions, are distributed at the surface region through refinement and coarsening procedures, a more efficient analysis of transient fluid flow with free surface is achieved. Using the proposed numerical technique, the collapse of a dam is analyzed. The numerical results agree well with the theoretical solutions as well as with the experimental results. Through comparisons with the numerical results of several cases using different types of grids, the efficiency of the proposed technique is verified.

• 한국수산과학회지
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• 제36권5호
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• pp.463-468
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• 2003

This study observed change of survival rate, activity and foot structure of the equilateral venus (Gomphina veneriformis) exposed to cadmium. Survival rate and activity of the clam exposed to cadmium was reduced with increase of exposure duration and concentration. Change of survival rate and activity was observed in the early exposure time (7 days) in the condition of above 1 77 mg/L and 0.88 mg/L, respectively. Activity reduction of the clam exposed to cadmium seems to be caused by epidermal layer deformation, muscle fiber fragmentation and muscular layer collapse of the foot.

• KSTLE International Journal
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• 제7권2호
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• pp.45-50
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• 2006

In this paper, the leakage safety of prestressed concrete structure including the insulation panels has been analyzed using a finite element analysis just after a collapse of 9% nickel inner tank. This FEM study shows that the outer tank may contain the leaked cryogenic liquid for the time being until the primary pump in the inner tank transports stored cryogenic liquids to the nearest LNG storage tank before the outer tank is demolished. This means that the total tank thickness from the insulation panel to the outer tank system safely may retain the leaked cryogenic fluids. The FE computed results indicate that the current structure in a full containment tank is obviously enough to securing the leak-proof safety of the tank system with two primary pumps.

• 한국측량학회지
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• 제19권1호
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• pp.67-75
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• 2001

지진 현상은 가장 심각한 인명과 재산의 피해를 초래하는 재해이며, 그 중 액상화 현상은 짧은 시간 안에 큰 피해를 줄 수 있는 재해중의 하나이다. 그 이유는 지반이 순간적으로 현탁액과 같은 상태가 되기 때문에 구조물들이 순간적으로 기울거나 붕괴하는 피해를 유발하게 된다. 이 연구는 춘천지역을 대상으로 지질도, 토양도, 수계망도, 지하수위 자료를 선정ㆍ분류하고, GSIS를 적용하여 경험적인 방법과 내진규정을 기준으로 액상화의 발생 가능지역을 평가하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.103-111
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• 2002

The objective of this study is to collect and classify bridge failures that occurred in domestic from 1974 through 2001 and to draw the engineering informations by analyzing the principal causes and the trends of the bridge failures. Total 45 failures of bridge were obtained and analyzed based on the factors such as time of failures, modes of failures, classification of materials of failed elements, types of failed elements, distribution of failure cases with respect to the highway grades. The critical problems of bridge failures are associated with the construction deficiencies, external causes, maintenance deficiencies, and design deficiencies. Since the study of failures in bridges would enhance the design and construction of safe bridges in the future, it would be needed to create data bases at the national level and to alter the related codes with identifying potential deficiencies from past failures data.