• 한국조명전기설비학회지:조명전기설비
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• 제10권5호
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• pp.43-51
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• 1996

박물관에서 조명에 의한 전시물의 손상이 일어나는 것을 최소화하기 위해서 적절한 조명 기준이 요구된다. 이러한 조명 기준의 작성을 위한 기초 자료를 얻기 위하여, 방사에너지의 파장의 함수로 전시물의 변색을 측정할 수 있는 장치를 구성하였다. 크세논 램프를 광원으로 사용하고, 빛은 여러 가지 차광 필터를 통과하여 시료에 입사한다. 여러 차광 필터 밑의 시료의 색을 측정함으로써 특정 파장 범위의 방사 에너지에 의한 사료의 변색을 추정하였다. 측정 결과, 식물 염료들은 단시간에 심한 변색을 보였으나, 전래 종이는 상대적으로 거의 변색이 되지 않았다. 측정 결과를 이용하여 다른 광원에 의한 변색을 예측할 수 잇으며, 이는 조명 기준 작성의 근거가 된다.

• 한국지진공학회논문집
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• 제1권4호
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• pp.11-20
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• 1997

우리나라 전통 초가삼간의 1/4 축소모델을 제작하여 암반지반 조건에 대한 내진성능실험을 수행하였다. Nahanni 지진파를 사용하여 최대 가속도 0.1g~0.6g 범위에서 거동을 분석하였다. 탄성한계에서 초가삼간의 고유진동수는 장방향의 경우 약 1.66Hz, 단방향의 경우 215Hz이다. 탄성한계에서의 감쇠비는 약 7%이다. 수평방향의 가속도응답은 입력에 비해 감소하며 입력가속도 수준이 증가할수록 감소율이 증가한다. 이는 사개맞춤으로 만들어진 목조 프레임의 비선형.비탄성 특성 때문이다. 전통 초가삼간 가옥은 고진동수가 지배적인 암반지반에서 매우 큰 내진성능을 나타내었다.

• 산업기술연구
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• 제21권B호
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• pp.125-132
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• 2001

Heat dissipation technology using flow resonant phenomenon is a kind of new concept in heat transfer area. A vibration exciter is needed to generate air turbulence which has the natural shedding frequency of heat system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator. An analytical dynamic model for this mechanical vibration exciter is presented and its' validity is verified by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. And in the experiment, the feedback control is used. During the experimental verification phase, it turns out the high modal resonant characteristics of vibrating plate are the major barrier against obtaining a high bandwidth vibration exciter.

• 산업기술연구
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• 제17권
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• pp.205-211
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• 1997

The problem of deteriorated highway concrete slab is very serious all over the world. Before making any decision on repair work, reliable non-destructive evaluation is necessary. One of the dependable methods is to evaluate the in-situ stiffness of the slab by means of obtaining the natural frequency. By comparing the in-situ stiffness with the one obtained at the design stage, the degree of damage can be estimated rather accurately. In this paper, the numerical modeling of vibration analysis to three span continuous reinforced concrete bridge with elastic intermediate support is presented.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.786-790
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• 2002

In this study, structural optimum design was applied to the girder of magnet over head crane. The optimization was carried out using ANSYS Code for the deadweight of girder, especially focused on the thickness of its upper, lower, side and reinforced plates. The weight could be reduced up to around 15% with constraints of its deformation, stress, natural frequency and buckling strength. The structural safety was also verified by the buckling analysis of its panel structure. It might be thought to be very useful to design the conventional structures for the weight save through the structural optimization. The objective function and restricted function were estimated by the orthogonal array, and the sensitivity analysis of design variable fur that was operated.

• Smart Structures and Systems
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• 제10권4_5호
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• pp.393-410
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• 2012

The 610 m high Canton Tower (formerly named Guangzhou New Television Tower) is currently considered as a benchmark problem for structural health monitoring (SHM) of high-rise slender structures. In the benchmark study task I, a set of 24-hour ambient vibration measurement data has been available for the output-only system identification study. In this paper, the vector autoregressive models (ARV) method is adopted in the operational modal analysis (OMA) for this TV tower. The identified natural frequencies, damping ratios and mode shapes are presented and compared with the available results from some other research groups which used different methods, e.g., the data-driven stochastic subspace identification (SSI-DATA) method, the enhanced frequency domain decomposition (EFDD) algorithm, and an improved modal identification method based on NExT-ERA technique. Furthermore, the environmental effects on the estimated modal parameters are also discussed.

• 산업기술연구
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• 제28권B호
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• pp.135-141
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• 2008

In this paper, the Proper Orthogonal Decomposition (POD) method, which is a statistical analysis technique to find the modal characteristics of a structure, is adapted to identify the modal parameters of a tall chimney structure. A wind force time history, which is applied to the structure, is obtained by a wind tunnel test of a scale down model. The POD method is applied on the wind force induced responses of the structure, and the true normal modes of the structure can be obtained. The modal parameters including, natural frequency, mode shape, damping ratio and kinetic energy of the structure can be estimated accurately. With these results, it may be concluded that the POD method can be applied to obtain accurate modal parameters from the wind-induced building responses.

• 한국소음진동공학회논문집
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• 제23권12호
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• pp.1073-1081
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• 2013

The definition of the radiation efficiency is very important to estimated underwater radiated noise of a ship. Considering the structure of the ship, it can be found that the hull of a ship consists of a lot of plates supporting by longitudinal and transverse stiffener. Therefore, various modes of the hull vibration occur related to the combination of these plates including stiffeners. In this paper, the method to define the radiation efficiency is suggested considering the vibration mode of the hull based on Uchida's experimental equation of the radiation efficiency. The suggested method is verified by the experiments with various kinds of naval vessels.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.577-582
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• 2001

Identification of damage of structures has recently received considerable attention in the light of maintenance and safety assessment under service loads. In buildings, the current techniques of safety assessment largely depend on partial experiments such as visual inspection, destructive and nondestructive tests which lead to overconsumption of time and cost as well as higher labor intensity. Therefore, a new trial for safety assessment is urgently needed today. In this respect, the vibration characteristics of buildings have been applied steadily to obtain a damage index of the whole building, but it cannot be established as a practical method until now. This study is aimed at investigating the application of damage identification methods using vibration characteristics of building. Numerical tests are performed on a apartment building. From the test results, it is observed that severity and location of damage can be estimated with a relatively small error by using natural frequency and mode shape data.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.27-34
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• 2003

Capacity Spectrum Method (CSM) defined in ATC-40 or FEMA-273 is a most widely used static inelastic analysis method to evaluate the performance level of the existing structures. In CSM, however, uncertainties and errors exist when lateral forces such as earthquake and wind loads are analyzed into equivalent static loads. This paper examines the accuracy of CSM for different structural parameters, such as natural frequency, yield strength and hardening ratio, and various soil conditions by comparing the estimated values to exact solutions obtained by time history analysis. Results indicate that the accuracy of CSM, in general, is influenced mostly by hardening ratio.