• Journal of Korean Association for Spatial Structures
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• v.8 no.5
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• pp.75-82
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• 2008

In this study, the possibility of vibration control of high-rise building structures by applying top-story isolation has been investigated. To this end, El Centro NS (1940) earthquake load is applied to 20- and 50-story building structures for numerical analysis. Artificial wind loads are used to evaluate the serviceability of example structures against wind vibration. As the number of isolated stories of example buildings is changed, structural responses has been evaluated to investigate optimal isolated building mass. And the natural period of isolation systems for top-story isolation is varied to investigate the improvement of control performance compared with the fixed base structure. Based on the analytical results, the top-story isolation system can be used as a hued mass damper and effectively reduce the structural responses of high-rise buildings against wind and seismic loads.

• Journal of KSNVE
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• v.6 no.3
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• pp.317-323
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• 1996

This paper proposes the method of experimental structural dynamic modification of fixture for environmental vibration test control. This method can predict the responses at any points on the fixture utilizing the experimental data, and structural dynamic modification of fixture is made using the predicted responses for the spectra at the specimen attachment points to meet the specified reference spectrum. From the results of controlling the fixture before and after modification by conventional control method and optimal reference spectrum, which has been previously reported by the authors, the proposed method is shown to be an effective one.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.51-62
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• 2006

To dale, lots of types of tuned mass dampers are developed and investigated to reduce dynamic responses of a structure due to various causes. In this study, control performance of semi-active tuned mass damper(STMD), that can change the damping of tuned mass damper in real time based on structural responses, was investigated with respect to various types of excitation employing numerical simulation. Skyhook control algorithm was used to appropriately modulate the damping ratio of semi-active damper that composes STMD. The control effectiveness of a STMD under harmonic and random excitation were evaluated using a single-degree-of-freedom (SDOF) structure in comparison with a conventional passive tuned mass damper (TMD). The robustness of a STMD and a passive TMD were compared along with the variation of the mass of a SDOF structure. The control performance of STMD using magnetorheological (MR) damper was also investigated in this study. Based on the numerical studios, it was shown that the control effectiveness of the STMD was significantly superior to that of a passive TMD with respect to harmonic and random excitation.

• Computational Structural Engineering
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• v.5 no.3
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• pp.105-112
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• 1992

The design of reactor internals requires the accurate vibration characteristics of each component for subsequent dynamic structural response analysis. For Korean standard nuclear power plant some modifications on the Control Element Assembly shroud from the reference design have been made. Since the shroud is complex in geometry having an array of vertical round tubes and webs in a square grid pattern, and being tied down by preloaded tie rods into position, it is planned to perform a vibration measurement program consisting of both experimental and analytical modal studies upon that component. To determine the proper test conditions, the pre-test analysis has been performed using the general purpose structural analysis program ANSYS. Also the effects of the number of master degrees of freedom, holes in the web and tie-rod preload on the natural frequencies are examined prior to the pre-test analysis. After decision of appropriate finite element model, frequency analysis and harmonic analysis are performed and ideas for the test conditions such as the number of measurement points, their locations, measurement frequency range and the excitation force level are determined.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.27-35
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• 2010

This paper presents the vibration control performance of the smart passive control system to suppress the undesired vibration of the structure subjected to the earthquake loadings. Smart passive control system is the MR damper-based control system augmented with electromagnetic induction(EMI) device which consists of permanent magnets and solenoid coils. According to the Faraday's law of electromagnetic induction, an EMI device produces electrical energy from the mechanical energy due to the reciprocal motions of the structure and provide it to the MR damper. The smart passive control system can be the simple and easy to implement and maintain control system by replacing the feedback control system including sensors, controllers and external power sources of the conventional MR damper-based semiactive control system with the EMI device. The control performance of the smart passive control system is evaluated through the set of shaking table test considering the various historical earthquake loadings.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.384-389
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• 2009

In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and Macro-Fiber Composite (MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.899-906
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• 2009

In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and macro-fiber composite(MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.

• Journal of KSNVE
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• v.2 no.3
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• pp.168-172
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• 1992

최근 자동차 분야에 있어서 많은 변화가 급속히 일어나고 있다. 70년대의 오일쇼크 이후 전륜구동 승용차의 보급이 급속히 확산되고, 연비 경쟁이 늘어났으며 소형. 경량화의 요구는 점차 증가되고 있다. 이후 80년대 들어 전자기술이 접목되면서 혁명적이라 할 수 있는 변화가 일어났고, 그 변화의 추세는 급속히 가속화되고 있다. 자동차의 전자화는 초기에는 공해 및 연비 개선 차원에서 시작됐으나, 이후 안전성 및 주행성능 향상을 겨냥했고, 이제는 인간감성까지 고려한 최적제어 측면에서 활발한 연구가 진행되고 있다. 이러한 변화는 소음. 진동분야에도 일어나, 차량이 점차 고성능. 경량화됨 에 따라 더욱 최적화된 구조물 설계를 요구하고 있고, 더 나아가 전자화를 도입 각종 노면 및 주행상태에 따라 최적의 승차감을 제공하는 전자제어 현가 시스템(E.C.S.)이 상품화되었고, 소리를 발생시켜 소음을 제거시키는 능동소음제어 시스템(ANC)의 실용화 단계를 앞두고 있다. 이러한 시점에 국내 자동차의 소음. 진동분야에 종사하는 많은 사람들에게, 실제 우리 국산화가 국내. 외적으로 소음. 진동부분이 어떻게 평가되고 있는지, 또 자동차 대중화 시대를 맞이한 국내의 많은 소비자들의 불만은 어느 정도인지를 인식시켜 각자의 사명감을 고양하고, 참고적으로 일본의 최근 자동차 분야의 소음. 진동 연구 동향을 소개하여 자동차 소음. 진동 대책 연구에 도움이 되고자 한다.

• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.52-57
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• 1994

본 개발에서는 주로 진동응답의 추정법에 대하여 검토하고 큰 성과를 얻었다. 이를 실제 설계에 활용해 나가는 것이 앞으로의 기본적인 과제이다. 또 이를 앞으로도 계속 개발해 나가기 위해서 는 다음과 같은 개발과제들을 들 수 있다. 1) 진동응답추정 .계산model 본 계발에는 Oil tanker와 산적화물선의 in-put generator(I/G)을 개발하였다. 이 이외의 선종 에 대하여도 본 개발에 의한 방법을 적용하게 되면 보다 정도 높은 계산 model로 새로이 refine해 나갈 수가 있다. .실선mode 해석전용 본 개발에 의하여 얻은 실선 mode해석 방법에 의하면 실선 계측으로부터 정확한 진동질량(m) 과 감쇄계수(d)를 얻게 된다. 이와 같은 m값과 d값의 자료를 더 축적하게 되면 진동응답 계 산정도를 한층 더 높일 수 있다. 2) 진동 제어 .종래의 설계방법과 본 개발에 의한 계산방법을 종합 적용하게 되면, 최적의 구조설계의 실용화 와 진동의 제어가 가능하게 될 것이다. .Enging, propeller 자체의 기진력을 경감시키는 연구는 본 개발에 들지 않고 앞으로의 과제로 남는다. .본 신형 주기방진stay의 개발은 본 진동제어의 idea에 도입하게 되면 또 다른 새로운 개발이 가능하다. .종래의 재료와 새로운 고성능 재료를 조합하게 되면 진동재어재료로서의 실용화가 가능하다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.882-889
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• 2010

Semi-active vibration control is one of the attractive control methods for space application due to its robustness as passive damping system and much higher damping performance than passive system. However, a chattering induced by the sudden variation of damping force at the time of On-Off switching of semi-active control device degrades pointing performance of the on-board payload. In this paper, to enhance the pointing performance of the on-board payload, we proposed a semi-active vibration isolation with a strategy for attenuating chattering effect. Numerical simulation results using simplified analysis model indicated that the proposed semi-active control strategy produced much better isolation performance than the conventional Bang-Bang control semi-active control laws derived from skyhook and LQ theories.