• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.11-18
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• 2011

Accurate modal identification analysis is required to reasonably perform a seismic qualification of safety-related electric equipment installed in nuclear power plants (NPPs). This study evaluates a variation of the modal properties of an electric equipment cabinet structure in NPPs according to the excitation levels. For the study, an actual electric equipment cabinet was selected as a specimen and was dynamically tested by using a portable exciter in accordance with the level of input vibration energy. Tests were classified into two sets: with-door cases, and without-door cases. Frequency response functions were computed from the signals of the acceleration responses and input motions measured from the vibration tests. A polynomial curve fitting algorithm was used to extract the modal properties from the frequency response functions. This study reviews the variation of the modal properties according to the variation of the excitation levels. The results of the study show that the modal frequencies and the modal dampings of the object specimen varies nonlinearly according to the excitation level of the test motion. Attaching the door increases the modal damping of the cabinet.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.1-8
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• 2021

In this paper, the cabinet shielding effectiveness (SE) including digital modules for nuclear power plants is analyzed depending on the internal structure and electromagnetic (EM) wave incidence angle. To analyze the SE, the cabinet and modules are modeled using the FEKO EM simulation tool. The SE is then obtained by comparing the electric field with and without the cabinet. In addition, the cabinet SE is observed by changing various conditions such as the spacing of each digital module, incidence angle, and the polarization of the EM wave at the 2.4 G[Hz frequency. To verify the results, the dipole antenna for SE measurements is fabricated, and the SE is measured in a semi-anechoic chamber. The result demonstrates that the SE by the cabinet structure can be expected to be higher when the polarization of the incident EM wave is horizontal to the ground and the distance between the digital modules is wide.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.197-199
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• 2005

원전계측제어시스템개발사업단(KNICS)에서 개발중인 원자로보호계통 캐비닛의 인간공학적 평가를 수행하였는데, 본 논문에서는 이에 대한 평가계획, 평가절차, 그리고 평가결과를 기술한다. 평가에는 기존의 시스템 경험이 있는 발전소계측제어요원과 인간공학 전문가 그룹이 참여하였는데, 새로 개발하는 시스템에 대한 교육 및 훈련이 평가전에 시행되었다. 평가는 운전성을 평가하기 위한 수행도 평가실험과 참여자의 주관적인 의견을 수집하기 위한 설문지 작성으로 구성하였는데, 평가실험을 위한 7개의 실험시나리오를 작성하여 실험설비에 구현하였다. 설문지는 기존 시스템의 운용중 발생하였던 문제점 및 장단점을 평가하기 위한 설문지, KNICS 보호계통 캐비닛의 활용후 개선점을 도출하기 위한 설문지, 그리고 기능적인 측면에서 운용전문가의 의견을 요구하는 설문지 둥의 3종류의 설문지로 구성하였다. 평가실험은 시나리오 운용순서에 따라 진행되었고, 모든 실험시나리오 실행과정은 비디오를 사용하여 기록하였다. 실험평가 데이터의 분석결과 KNICS 원자로보호계통은 유지보수 측면에서 기존의 시스템보다 우수한 것으로 평가되었으며, 화면설계 및 기기설계시 반영하여야 할 개선사항이 도출되었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.5
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• pp.57-63
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• 2008

This paper presents a seismic response prediction method using vibration tests of cabinet-type electrical equipment installed in a nuclear power plant. The proposed method consists of three steps: 1) identification of earthquake-equivalent forces based on lumped-mass system idealization, 2) identification of a state-space-equation model relating input-output measurements obtained from the vibration tests, 3) seismic prediction using the identified earthquake-equivalent forces and the identified state-space-equation. The proposed method is advantageous compared to other methods based on FEM (finite element method) model update, since the proposed method is not influenced by FEM modeling errors. Through a series of numerical verifications on a frame model and 3-dimensional shell model, it was found that the proposed method could be used to accurately predict the seismic responses, even under considerable measurement noise conditions. Experimental validation is needed for further study.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.3
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• pp.23-30
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• 2010

Seismic qualification (SQ) is required prior to the installation of safety related electrical cabinets in nuclear power plants (NPPs). Modal identification of the electrical equipment is one of the most significant steps to perform SQ, and is an essential process to construct a realistic analytical model. In this study, shaking table tests were conducted to identify a variation of the dynamic characteristics of a seismic monitoring system cabinet installed in NPPs according to the excitation level. Modal identification of the cabinet has been performed by a frequency domain decomposition method. The results of this study show that the dynamic properties of the cabinet are nonlinearly varied according to the excitation level and the specimen behaves significantly in a nonlinear manner under safe shutdown earthquake motion in Korea. The main sources of the nonlinear behavior of the specimen have been judged by friction forces and geometrical nonlinearity rather than material nonlinearity. The nonlinear variation of the dynamic characteristics of the electrical cabinet might be accepted as an important fact that should be considered during the SQ of safety related equipment.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.53-61
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• 2019

The seismic capacity of electric cabinets in Nuclear Power Plants (NPPs) should be qualified before installation and be maintained during operation. However it can happen that identical devices cannnot be produced for replacement of devices mounted in electric cabinets. In case of when no In-Cabinet Response Spectrum (ICRS) is available for new devices, ICRS can be generated by using Finite Element Analysis (FEA). In this study we investigate structural response and ICRSs of battery charger which is supplied to NPPs. Test results on the battery charger are utilized in this study. The response is measured by accelerometers installed on the housing of the battery charger and local panels in the battery charger. Numerical analysis model is established based on resonant frequency search test results and validated by comparison with 2 types of earthquake testing results. ICRSs produced from the numerical model are compared with measured ICRSs in the seismic tests. Developed analysis model is a simple reduced model and anticipates ICRSs quite well as measured response in the tests overall despite of its structural limitation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.709-719
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• 2023

In general, most of the electrical equipment responsible for control within power plants is housed in self-standing cabinets. These cabinets are typically fixed to a slab using post-installed anchors. Although the fixation method of using post-installed anchors provides stability, there is a risk of conductor failure due to external forces, including moments. However, the performance assessment of current anchors is only evaluated through uniaxial material tests. Therefore, the primary purpose of this study is to compare the static performance of post-installed anchors, considering on-site installation conditions, with their performance in material tests and to analyze the behavioral characteristics of the anchors. While conducting experiments using actual cabinets would be ideal, practical and spatial constraints make this approach difficult. As an alternative, experiments were conducted using a test specimen consisting of a steel column and a support. As a result, the pull-out performance of anchors reflecting on-site installation conditions was measured to be about 10% higher than that observed in material tests. The trends in load reduction and the point of maximum performance for the anchors also differed. To verify the reliability of the experimental study, a 3D FEM analysis was performed, which will provide predictive information on the loads transferred to the post-installed anchors for structural performance evaluations of electrical cabinets using shaking table test in the future.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.75-84
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• 2010

An in-cabinet response spectrum should be generated to perform the seismic qualification of devices and instruments mounted inside safety-related electrical equipment installed in nuclear power plants. The response spectrum is available by obtaining accurate seismic responses at the device mounting location of the cabinet. The dynamic behavior of most of electrical equipment may not be easily analyzed due to their complex mass and stiffness distributions. Considering these facts, this study proposes a procedure to estimate the seismic responses of a structure by a combination of a test and subsequent analysis. This technique firstly constructs the modal equations of the structure by using the experiment modal parameters obtained from the impact test. Then the seismic responses of the structure may be calculated by a mode superposition method. A simple steel frame structure was fabricated as a specimen for the validation of the proposed method. The seismic responses of the specimen were estimated by using the proposed technique and compared with the measurements obtained from the shaking table tests. The study results show that it is possible to accurately estimate the seismic response of the structure by using the experimental modal parameters obtained from the impact test.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1786-1787
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• 2011

화력발전소에 사용되는 제어시스템을 개발함에 있어 하드웨어 분야는 시스템의 안정성과 신뢰성 확보를 위해 반드시 기기검증시험을 통과한 후 적용하여야 한다. 이러한 시험은 제어모듈의 모든 종류의 개별 시험과 실제 사용하고자 하는 구성으로 캐비닛에 모두 장착한 상태에서 시험하여야 한다. 이번 시험은 제어시스템을 설계하고 제작한 후 설계 제원대로 성능을 가지고 있는지에 대한 검증을 목적으로 하였으며, 유럽규격의 CE 마크 획득에 필요한 기준으로 시험을 수행한 기준을 설명한다.

• 전기의세계
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• v.52 no.9
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• pp.24-32
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• 2003

원전에서 사용되는 계측제어계통 기기들의 국산화를 위하여 수행중인 KNICS 사업의 개발내용을 요약하였다. 본 연구개발은 계측제어계통 구성의 근간이 되는 핵심 기기를 PLC와 DCS로 선정하여 국산화하고, 이를 기반으로 원전에서 요구되는 각종 보호계통, 제어계통 및 감시계통 캐비닛을 개발한다. 원전 적용시 필수적으로 거쳐야 하는 인허가 획득을 위하여 개발요건 수립에서부터 기기검증에 이르기까지 체계적인 계획하에 개발을 추진중에 있으며, 개발결과는 국내 후속원전 건설 및 기존 원전의 기기교체 시 사용가능할 것으로 기대한다.