• 한국강구조학회 논문집
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• 제9권4호통권33호
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• pp.625-635
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• 1997

기초 분리 기법과 분리 장치의 지진 하중에 대한 구조물의 에너지 전달력의 감소 효과에 대한 인식은 증가되어 왔으나, 기초 분리 교량의 지진 응답을 예측하기 위한 수단으로 사용되는 비선형 동적 해석 방법은 소요되는 경비 및 장비의 제한으로 설계용으로는 제한적이다. 본 연구는 기초 분리 교량의 설계에 있어서 시간 이력 해석법에 의하지 않고, 탄성 해석법의 적용을 위한 기초 자료로써, 지진 발생시 구조물의 비선형 응답의 해석의 탄성 해석법 적용성을 검토하였다. 본 연구는 기초 분리 교량의 하중-변위를 항복전과 항복후 상태로 분리하여, 주기 이전과 유효 주기, 모드 기여율의 변화를 고찰하였다. 또한, 교각 높이별 P.C교에 인공 지진파를 이용한 시간 이력 해석을 수행하여 분리 장치의 상태 변화를 고려한 모드 해석법과 비교하였다. 해석 결과, 분리 장치의 상태 변화는 주로 제1 모드 주기에 영향을 미치며, 지진 응답은 분리 장치의 상태 변화에 따라 지배되나 일정 범위로 수렴하였다. 이에 bilinear 분리 장치에 의한 비선형 지진 응답의 유효 강성에 의한 모드 해석의 적용 가능성을 확인하였다. 또한, bilinear 장치로 기초 분리된 교량에 대해 교각 높이 변화를 고려한 선형 탄성 해석과 비선형 시간 이력 해석 결과를 비교하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.432-439
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• 2000

According as ground acceleration becomes to exceed gravity acceleration recently, design is impossible or economical efficiency is poor in existing seismic design method. So increase of seismic isolated bridges is currently in progress. However, because base isolation design method is developed in high seismic regions. it may not be compatible in Korea. Therefore, this research has objective to evaluate ductility of pier and response modification factor according to the ductility of pier in seismic isolated bridges and to adapt to seismic characteristics in Korea. For this purpose, nonlinear analysis is accomplished with so many time histories derived from spectral density function compatible with response spectrum described in the design code and base isolation system modeled linear system, bi-linear system, and friction system. Through application of the proposed method, we had result that it may be compatible that response modification factor for the seismic isolated bridges is smaller than half of that for the conventional bridges when natural period of structures exceeds proper level.

• Structural Engineering and Mechanics
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• 제8권4호
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• pp.411-419
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• 1999

A nonlinear model for time-step analysis of bridges subjected to two orthogonal horizontal components of earthquake motions was developed. The focus of the study was on elastomeric isolators with or without lead cores. The hysteretic behavior of the isolators, the columns, abutments, and shear keys was taken into account. The nonlinear analysis showed that, contrary to linear theory prediction, the use of isolators does not necessarily increase the displacement of the superstructure. Furthermore, it was shown that properly designed isolators can reduce the ductility demand in RC bridge columns substantially.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1046-1049
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• 2002

In this paper, a sub-harmonic dual-gate FET mixer for IMT-2000 base-station was designed by using single-gate FET cascode structure and driven by the second order harmonic component of LO signal. The dual-gate FET mixer has the characteristic of high conversion gain and good isolation between ports. Sub-harmonic mixing is frequently used to extend RF bandwidth for fixed LO frequency or to make LO frequency lower. Furthermore, the LO-to-RF isolation characteristic of a sub-harmonic mixer is better than that of a fundamental mixer because the frequency separation between the RE and LO frequency is large. As RF power is -30dBm and LO power is 0dBm, the designed mixer shows the -47.17dBm LO-to-RF leakage power level, 10dB conversion gain, -0.5dBm OIP3, -10.5dBm IIP3 and -1dBm 1dB gain compression point.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.341-348
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• 2002

In these days, The base isolation system is often used to improve the seismic capacity of the structures instead of conventional techniques of strengthening the structural members. The purpose of this study is to evaluate dynamic property evaluation of control equipment using lead Lead Rubber Bearing. In this study, a base isolation test of seismic monitoring control cabinet with LRB(lead rubber bearing) was performed. The cabinet will be installed on access floor in MCR(main control room) of nuclear power plant. Details and dynamic characteristics of the access floor were considered in the construction of testing specimen. N-S component of El Centre earthquake was used as seismic input motion. Acceleration response spectrums in the top of cabinets showed that the first mode frequency of cabinet with LRB(lead rubber bearing) was shifted to 7.5 Hz in compared with 18Hz of cabinet without LRB and the maximum peak acceleration was reduced in a degree of22 percent from 2.35 g to 1.84 g

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.383-390
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• 2001

Various base isolation systems, which are widely used, are compared for aseismic performances of multi-span continuous bridge. They are the P-F, RB, LRB, R-FBI and EDF systems. Sensitivity analyses are carried out to determine the design parameters of various devices. The design parameters, natural period of the isolated bridge and friction coefficient of the bearing, are determined by the reciprocal relationship between displacement and bending moment of the structure. Then the relative effectiveness of the bearings is described. Bridge with the R-FBI system shows the smallest peak displacement of deck whereas bridge with the EDF system shows the smallest peak bending moment of the lower end of pier in numerical examples. Furthermore, the peak responses of bridge with the friction type bearing are less sensitive to substantial variations in the frequency range and intensity of the ground excitation than those with the rubber type bearing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.142-147
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• 2003

This paper is concerned with the experiment of vibration isolation device whit can cope with heave, pitch and roll type vibrations. This new device consists of S-shaped piezoceramic actuators supporting each corner of the plate. Small piezoceramic sensors are located at the middle of each side. This paper also presents the development and the movement of the system. The active control technique was also developed to cope with base excitation. Experimental results show that vibrations can be reduced by the new device in the case of base excitation of harmonic type.

• 한국공간구조학회논문집
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• 제18권3호
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• pp.105-116
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• 2018

The objective of this study is to investigate the response reducing effect of a seismic isolation system installed between 300m dome and supports under both horizontal and vertical seismic ground motion. The time history analysis is performed to investigate the dynamic behavior of single layer lattice domes with and without a lead rubber bearing seismic isolation system. In order to ensure the seismic performance of lattice domes against strong earthquakes, it is important to investigate the mechanical characteristics of dynamic response. Horizontal and vertical seismic ground motions cause a large asymmetric vertical response of large span domes. One of the most effective methods to reduce the dynamic response is to install a seismic isolation system for observing seismic ground motion at the base of the dome. This paper discusses the dynamic response characteristics of 300m single layer lattice domes supported on a lead rubber seismic isolation device under horizontal and vertical seismic ground motions.

• 한국지진공학회논문집
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• 제17권2호
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• pp.53-59
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• 2013

Several researches have been studied to enhance the seismic performance of nuclear power plants (NPPs) by application of seismic isolation. If a seismic base isolation system is applied to NPPs, seismic performance of nuclear power plants should be reevaluated considering the soil-structure interaction effect. The seismic fragility analysis method has been used as a quantitative seismic safety evaluation method for the NPP structures and equipment. In this study, the seismic performance of an isolated NPP is evaluated by seismic fragility curves considering the soil-structure interaction effect. The designed seismic isolation is introduced to a containment building of Shin-Kori NPP which is KSNP (Korean Standard Nuclear Power Plant), to improve its seismic performance. The seismic analysis is performed considering the soil-structure interaction effect by using the linearized model of seismic isolation with SASSI (System for Analysis of Soil-Structure Interaction) program. Finally, the seismic fragility is evaluated based on soil-isolation-structure interaction analysis results.

• 전산구조공학
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• 제27권1호
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• pp.16-25
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• 2014