• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1105-1111
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• 2010

The Korea Atomic Energy Research Institutes has been developing the SMART (System integrated Modular Advanced ReacTor), an environment-friendly nuclear reactor for the generation of electricity and to perform desalination. SMART reactors can be exposed to various external and internal loads caused by seismic and coolant flows. The CRDM(control rod drive mechanism), one of structures of the SMART, is a component which is adjusting inserting amount of a control rod, controlling output of reactor power and in an emergency situation, inserting a control rod to stop the reactor. The purpose of this research is performing the analysis of dynamic characteristic to ensure safety and integrity of structure of CRDM. This paper presents two FE-models, 3-D solid model and simplified Beam model of the CRDM in the coolant, and then compared the results of the dynamic characteristic about the two FE-models using a commercial Finite Element tool, ABAQUS CAE V6.8 and ANSYS V12. Beam 4 and beam 188 of simplified-model were also compared each other. And simplified model is updated for accuracy compare to 3-D solid.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.69-78
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• 2007

In this study, for the evaluation of seismic safety of the isolated Emergency Diesel Generator (EDG) System more quantitatively, the seismic fragility analysis method were proposed. Using the proposed method, seismic fragility analysis performed and a seismic risk of EDG system was present. The fragility analysis performed not for an existing EDG system but also for an isolated EDG system which increases the seismic capacity. At first, numerical models for existing and isolated EDG system were constructed and seismic response analysis performed according to input seismic waves and peak ground accelerations. An uncertainty factors and failure modes of both fixed and isolated EDG system were assumed for fragility analysis. The HCLPF values were evaluated for the compare the improvement effect using the isolation system. As a result, the isolation system can make better the seismic fragility of EDG system, but the failure of isolation system was govern the behavior of whole system.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.155-175
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• 2005

Soil and rock dynamic properties such as shear wave velocity (VS), compressional wave velocity (VP) and corresponding Poisson's ratio ( v ) are very important geotechnical parameters in predicting deformational behavior of structures as well as practicing seismic design and performance evaluation. In an effort to measure the parameter efficiently and accurately, various bore-hole seismic testing techniques have been, thus, developed and used during past several decades. In this study, cross-hole seismic testing technique which is known as the most reliable seismic method was adopted for obtaining geotechnical dynamic properties. To perform successfully the cross-hole test for rock as well as soil layers regardless of the ground water level, spring-loaded source which impact laterally a subsurface ground in vertical bore-hole was developed and applied at three study areas, which contain four sites composed of two existing port sites and two new LNG storage facility sites. The geotechnical dynamic properties such as VS, VP and v with depth were efficiently determined from the laterally impacted cross-hole seismic tests at study sites, and were provided as the fundamental parameters for the seismic performance evaluation of the existing ports and the seismic design of the LNG storage facilities.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.265-273
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• 2008

The problem controlling lateral drift by the wind and the earthquake is very important in high rise buildings. But, outrigger system, generally used for residential tall buildings in Korea, has weak points with the occupancy of special space, the difficult construction and the long duration of works. On the other hand, the damper reduces story drifts of building structure by absorbing vibration energy induced by the dynamic loads and the application of damper systems is relatively simple. Also, the lateral drift control system such as outrigger system may raise the wind vibration problem of serviceability like human comfort and this problem may need another vibration control devices. Accordingly, we analyze the effect of the drift control using various dampers to substitute for outrigger system as the efficient system in residential tall buildings.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.443-450
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• 2002

본 논문에서는 미국토목학회(ASCE)의 사장교에 대한 첫번째 벤치마크 문제를 이용하여 제어-구조물 상호작용을 고려한 새로운 반능동 제어 기법을 제안하였다. 이 벤치마크 문제에서는 2003년 완공 예정으로 미국 Missouri 주에 건설 중인 Cape Girardeau 교를 대상 구조물로 고려하였다. Cape Girardeau 교는 New Madrid 지진구역에 위치하고, Mississippi 강을 횡단하는 주요 교량이라는 점 때문에 설계단계에서부터 내진 문제에 대하여 자세하게 고려되었다. 상세 설계 도면을 기반으로 하여 교량의 전체적인 거동 특성을 정확하게 나타낼 수 있는 3차원 모델이 만들어졌고, 사장교의 제어 성능에 관련된 평가 기준이 수립되었다. 본 연구에서는 제어 가능한 유체 감쇠기에 속하는 MR 유체 감쇠기를 제어 장치로 제안하였고, 기존 연구에서 MR 유체 감쇠기를 포함한 구조물의 제어에 효율적이라고 검증된 clipped-optimal 알고리듬을 제어 알고리듬으로 사용하였다. 또한, 실제 규모의 MR 유체 감쇠기 실험 결과를 이용하여 수치해석에 이용할 수 있는 동적 모델을 개발하였다. MR 유체 감쇠기는 제어 가능한 에너지 소산장치이며 구조물에 에너지를 가하지 않기 때문에 제안된 제어 기법은 한정입출력 안정성이 보장된다. 수치해석을 통해, MR 유체 감쇠기를 이용한 반능동 제어 기법이 사장교의 응답 감소에 효과적인 방법임을 증명하였다.

• Journal of the Korean Society for Railway
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• v.13 no.4
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• pp.440-446
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• 2010

This paper was investigated on the laminated rubber bearing, which mitigates damages of bridges from threat of earthquakes. Laminated rubber bearing can bear large loads for long periods of time and be capable of large deformations during an earthquake. To evaluate seismic isolation with laminated rubber bearing on several earthquake waves, we performed a shaking table test. In this test, deck acceleration was measured by accelerometers and shear force on piers was surveyed by load cells. Furthermore, seismic capacity of isolated systems with laminated rubber bearing was compared with non-isolated systems through shaking table test. The results show that deck acceleration and shear force were relatively reduced by laminated rubber bearing.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.299-300
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• 2022

구조물의 내진보강방법 중에서 가장 널리 이용되는 방법인 강재 이력형 감쇠장치는 수평하중에 대한 응력-변위 곡선을 이용하여 지진 에너지를 소산시키는 방법인데, 이 경우 편심하중 등에 의해서 부재가 면 외 방향으로 거동하여 응력-변위곡선이 불규칙하여 그 결과의 신뢰성이 떨어지는 경우가 있다. 이러한 형상을 방지하기 위해서는 별도의 채널(Channel)을 시공하는 불편함을 감수해야 하며, 또한 수평력이 반복적으로 작용할 때 그 효과를 장담할 수 없는 문제점이 있다. 본 연구에서는 강재 스트립과 스프링을 결합한 댐퍼를 고안하여 스프링은 탄성변형을, 강재 스트립은 소성변형을 받게 하는 혼합형 댐퍼를 개발하고자한다. 여기서, 스프링은 복원력으로 작용하여 반복하중에 대한 저항성을 키우고 강재 스트립의 하중변위 곡선을 규칙적으로 하는 역할을 수행하게 되며 에너지 소산량을 계산할 때 편리함과 정확도를 높이고자 한다. 강재 스트립의 폭과 길이는 일정하지만 두께를 변화시켜서 5종류를 선택하였으며, 댐퍼 1개당 3개의 스트립을 정삼각형 형태로 배치하고 그 중심에 상당한 강성을 갖는 스프링을 갖는 형태로 제작하였다. 댐퍼 시험체는 5개를 제작한 후, 이 댐퍼를 구조물에 배치하였을 때의 지진에 대한 에너지 소산량과 부재력을 검토하여 댐퍼의 안전성(Safety)를 검증하고자 한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2000_2001
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• 2009

최근 옥외 변전소 형식으로 많이 채택되고 있는 Gas Insulated Switchgear(GIS) 변전설비는 라인 구조물 형태로서, 온도응력에 대한 길이방향의 변형을 수용토록 하기 위하여 GIS 곳곳에 벨로우즈가 설치되어 있다. 특히, GIS는 강재 지지대로 높은 위치에 설치되어 지진 시 지반보다 높은 가속도를 받기 때문에 벨로우즈의 설치 위치가 GIS에 영향을 줄 가능성이 크다. 따라서 본 연구에서는 다양한 경우의 민감도 해석을 통하여 벨로우즈의 위치가 GIS의 내진성능에 미치는 영향을 분석하였으며, 그 결과 최적의 벨로우즈 위치조건을 도출하였다.

• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.35-42
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• 2017

This study develops a new hybrid passive energy dissipation device for seismic rehabilitation of an existing structure. The device is composed of a friction damper combined with a steel plate with vertical slits as a hysteretic damper. Analytical model is developed for the device, and the capacity of the hybrid device to satisfy a given target performance is determined based on the ASCE/SEI 7-10 process. The effect of the device is verified by nonlinear dynamic analyses using seven earthquake records. The analysis results show that the dissipated inelastic energy is concentrated on the hybrid damper and the maximum interstory drift of the SMRF with damping system satisfies the requirement of the current code.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.79-89
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• 2000

In this paper, the seismic analysis and the modeling techniques have been introduced for aseismic performances assessment, when seismic isolation bearings are applied on a real bridge. Nonlinear time-history analysis is carried out using finite element analysis program. In this study, EI Centro earthquake(1940, N00W), Mexico earthquake(1985, N90W), and earthquake simulation from modified SIMQKE are used as earthquake ground excitations. The seismic response of seismically isolated bridge is compared with that of a bridge using conventional Pot Bearings, after obtaining the displacements of the deck, the deformations of the piers, shear forces and moments of the bottoms of the piers. The analytical analysis results show that seismic isolation bearing, especially seismic isolation bearings with sliding mechanism, could reduce earthquake forces.