• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1423-1428
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• 2000

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.63-64
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• 2006

본 연구에서는 광에너지를 화학적인 에너지로 변환할 때, 디바이스의 전하전달 매개를 위한 electron transfer mediator로서 널리 이용되는 Viologen이 자기조립화된 수정진동자률 전기화학법의 하나인 순환전압전류법(Cyclic Voltammetry)을 이용하여 산화 환원 반응 (redox reaction) 특성과 주사속도와 피크전류와의 상관관계를 분석하였다. 먼저 수정진동자를 친수 처리한 후, 메탄올 용액과 아세토니트릴 용액을 섞은 용매에 Viologen 분자를 자기조립 (self-assembly)하여, 전해질 용액의 농도 변화에 따른 산화 환원반응 특성과 피크전류의 값을 측정하였다 주사 속도를 2 배씩 증가하여 피크전류와의 상관관계를 조사한 결과, 선형적인 증가를 보였으며, 이를 통해 가역적인 반응(reversible reaction)이 일어났음을 확인할 수 있었다. 또한, 산화 환원 반응과 동시에 측정된 수정진동자의 공진 주파수(resonant frequency) 변화로부터 전하이동(charge transfer) 특성에 의해 반응에 참가한 이온의 질량을 알 수 있었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제15권3호
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• pp.409-420
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• 2002

This paper proposed a technique of structural re-analysis for the evaluation of dynamic responses of bridge structure under moving loads using experimental modal results. For successful structural re-analysis, it is required to have accurate estimation techniques of the modal characteristics of bridge structures. The natural frequencies and mode shapes were identified by direct fourier analysis techniques and damping ratios by the random decrement method, respectively. An interpolation method was also proposed for the extension of mode shape measured on limited DOFs. Second, the structural reanalysis was performed using moving mass model and identified modal parameters. The results from the reanalysis show that the proposed technique is very reasonable to evaluate the actual behavior of bridge structures under moving loads.

• Journal of the Korean Chemical Society
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• 제28권1호
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• pp.26-33
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• 1984

The rate constants for the following vibration-to-vibration energy exchange reactions have been calculated theoretically for the temperature range from 300 to 800K and for n = 2 to 5. HF(v=n) + DF(v=0) ${\to}$ HF(v=n-l) + DF(v=l) + ${\Delta}E$(a) DF(v=n) + HF(v=0) ${\to}$ DF(v=n-l) + HF(v=l) + ${\Delta}E$(b) In calculation the loosely-held, non-rigid dimer collision model and semiclassical method have been employed. The results show that the rate constants for the processes (a) are much greater than those for the processes (b). Also, it is found that the rate constants for the processes (a) increase with decreasing temperature and with increasing quantum number, while those for the processes (b) show the opposite tendencies. These findings are explained in terms of the sign and magnitude of the energy mismatch, ${\Delta}E$.

• Journal of Korean Society of Steel Construction
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• 제26권5호
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• pp.375-383
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• 2014

In Seoul, total 166 places of foot-bridges were constructed but a study on correlation between resonance occurrence status by gait vibration and natural frequency by each span and that between span based on structural system and natural frequency is very unsatisfactory in reality. Consequently in this study, time series wave form, power spectrum and natural frequency were analyzed based on resonance occurrence by targeting 65 places of foot-bridges being constructed in Seoul through convenient and simple portable vibration meter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 1992년도 추계학술대회논문집; 반도아카데미, 20 Nov. 1992
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• pp.124-129
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• 1992

이동 집중력 및 집중질량에 의한 이동하중을 받는 직사각형 보강판에 대하 여 보강재효과집중 모델링방법에 의거하여 보강판을 등방성 박판 및 보강재 효과를 반영한 등가보요소로 이루어진 판-보 조합체로 유한요소 모델링하고 Newmark의 직접 시간적분법을 이용한 동응답 해석방법을 정식화하였다. 일 련의 수치계산 예를 통하여 본 연구에서 제시한 방법이 이동하중을 받는 보 강판의 동응답 해석문제에 효과적으로 적용될 수 있음을 확인하였다. 아울러 parametric study를 통하여 이동하중이 작용하는 보강판의 동응답특성은 이 동하중의 질량효과를 고려하는 경우와 고려하지 않는 경우 매우 달라지며, 이동하중에 의한 동적응답은 이동속도가 증가할수록 정하중에 의한 응답보 다 증폭되어 나타나고 증폭비율이 질량효과를 고려할 경우 훨씬 더 커짐을 확인하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제26권1호
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• pp.27-38
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• 2016

The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.

• Journal of the Society of Disaster Information
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• 제13권1호
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• pp.73-80
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• 2017

In this study, the panel joint behavior by the vehicle load moving on precast panel is analyzed. The frame was made for loading and the behavior was determined by using each measuring device. The static response of the panel was examined and compared with the theoretical value, and it was found that the characteristics were very reasonable. In addition, acceleration, velocity, and displacement were measured for dynamic impact evaluation, and the characteristics of moving load were analyzed in the test. The vibration frequency of the panel was measured for the dynamic response by the moving load, and the vibration characteristic was considered to be sensitive to the range of the load. As a result, it is considered that the dynamic response of the connection part should be careful in design because the characteristics are different according to the connection method.

• Journal of the Earthquake Engineering Society of Korea
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• 제5권5호
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• pp.35-45
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• 2001

Recently, the floor systems those require large open space may have low inherent damping due to the decline of the use of curtain walls. Furthermore, the use of the high strength materials has resulted in more flexible and longer spanning in floor systems. The long span structures such as shopping malls, offices and large assembly rooms may lead to significant dynamic response due to human activities. Excessive vibrations make the occupants uncomfortable and deteriorate the serviceability of buildings. It is now proved that footfall loading is the major source of floor vibrations. The common method of application of walking loads for the vibration analysis of structures subjected to walking loads is to inflict measured walking loads and periodic function at a node. But this method could not account for the moving effect of walking. In this study, natural frequency and damping ratio of example structure are evaluated by heel drop tests. And the application of equivalent walking loads is used for on efficient vibration analysis of the plate structures subjected to walking loads.

• Journal of the KSME
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• 제35권10호
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• pp.917-923
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• 1995

회전체 진동은 주로 밸런싱에 의해 줄일수 있지만 위험속도에서 나타나는 회전체 진동은 종종 피할 수 없다. 전자기 베어링은 이러한 회전체 진동을 능동적으로 제어하는 방법으로써 사용된다. 비접촉으로 회전체에 힘을 작용하는 동흡진기(dynamic vibration absorber)는 기존의 것에 비해 새로운 것을 필요로 하지 않는 아주 간단한 방법이다. 영구자석으로 구성된 자석 댐퍼는 비접 촉동흡진기의 일종이지만 영구자석만으로는 적절한 감쇠 성능을 만족시킬 수 없다. 따라서 영 구자석과 전자석을 동시에 사용하는 하이브리드 자석이 넓은 운전영역에서 좋은 진동제어 성능을 자지기 때문에 유용하다. 전력공급의 편리성을 위해서 하이브리드 자석을 합진기쪽에 설치하고 여러 개의 편으로 된 영구자석은 회전체의 주위에 부착하였다. 본 연구의 목적은 수직 회전 체(vertical rotor)의 진동을 제어하기 위해서 전자기력을 이용하는 하이브리드 관성 댐퍼를 개 발하는 것이다. 지금까지 전자석을 이용한 진동제어는 여러 저자에 의해 연구되어 왔으며 자기 베어링은 회전체의 진동을 제어하기 위한 전형적인 예이다. 그러나 회전체에 능동관성 댐퍼를 직접 적용한 예는 없었다. 이동흡진기는 전자석의 반발력(repulsive force)을 이용하고 흡진기의 운동에 의해 에너지가 감쇠된다. 반면에 자기 베어링에서는 전자석의 흡인력(attractive force)을 이용한다.