• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1224-1230
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• 2007

In this study, a new modal test method is presented to evaluate vibration characteristic of the nano imprint stage system. Since it is difficult to measure vibration level without contacting the machine component, non contacting modal test method, laser scanning system is ultrared. Finite element analysis results are compared with the modal test results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.401.2-401
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• 2002

An unconstrained tuning fork with a 3-D model has been numerically analyzed by Finite Element Method (FEM) and Boundary Element Method (BEM). The first three natural frequencies were calculated by the FEM modal analysis. Then the change of the modal frequencies was examined with the variation of the tuning fork length and width. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1925-1932
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• 2000

Damage detection methods using vibration modes are investigated on ring structures and. modal behavior of the slightly asymmetric rings is examined. Mode shapes changes, MSER(modal strain energy ratio) and MCR(modal curvature ratio) are applied to identify the locations of faults or damages. Parameters are calculated and compared by finite element analysis on rings with designed local damages. Damages are modeled as reduced stiffness in the analysis. The results show MSER and MCR can be proper factors to detect local damages in ring structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1436-1437
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• 2008

In this work, we investigate the electrical and electromagnetic behaviors of the power-bus with a variety of shapes of aperture, on the signal integrity, using a rigorous methods(Modal or MoM) along with Modal analysis method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.622-627
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• 2001

The paper presents the possibilities of a wide practical application of the modal analysis methods in dynamic testing of vertical pump. A pneumatic impact of testing vertical pumps submerged under deep water was developed and successfully applied. The problem with the enviroment is the it causes significants changes in modal parameters, compared with those in the airenviroment.

• Structural Engineering and Mechanics
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• 제14권1호
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• pp.1-20
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• 2002

Investigated in this study are the modal characteristics of the eccentric cylindrical shells with fluid-filled annulus. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of eccentricity on the modal characteristics of the shells is investigated using a finite element modeling.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.701-707
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• 2000

In this work, we propose to employ magnetostrictive sensors to develop a new non-contacting modal testing method. Specific applications are made in the modal testing of a beam in bending. The role of bias magnetic fields in measuring bending waves is addressed and an approximate analysis to explain the principle to measure bending signals is carried out. The measured modal data by the present method agree well with those by conventional methods using accelerometers.

• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.184-194
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• 2016

In existing identification methods for on-orbit spacecraft, such as eigensystem realization algorithm (ERA) and subspace method identification (SMI), singular value decomposition (SVD) is used frequently to estimate the modal parameters. However, these identification methods are often used to process the linear time-invariant system, and there is a lower computation efficiency using the SVD when the system order of spacecraft is high. In this study, to improve the computational efficiency in identifying time-varying modal parameters of large spacecraft, a faster recursive algorithm called fast approximated power iteration (FAPI) is employed. This approach avoids the SVD and can be provided as an alternative spacecraft identification method, and the latest modal parameters obtained can be applied for updating the controller parameters timely (e.g. the self-adaptive control problem). In numerical simulations, two large flexible spacecraft models, the Engineering Test Satellite-VIII (ETS-VIII) and Soil Moisture Active/Passive (SMAP) satellite, are established. The identification results show that this recursive algorithm can obtain the time-varying modal parameters, and the computation time is reduced significantly.

• 한국항만경제학회지
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• 제27권2호
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• pp.137-161
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• 2011

본 연구의 목적은 국내 외 전환교통의 추진실태의 분석과 시사점을 토대로 한국에서 전환교통을 수립하기 위한 기본정책방향을 제시하는 데 있다. 중요한 연구내용은 전환교통정책의 이론적 고찰, 국내 외 전환교통실태와 정책분석, 한국의 전환교통정책의 수립방향 등을 포함하고 있다. 전환교통(modal shift)은 여객 또는 화물을 운송하는 데서 운송수단을 화물차에서 철도 또는 선박으로 전환하는 것이다. 전환교통은 범세계적인 환경규제의 시대에 친환경 물류체계를 달성할 수 있는 중요한 정책수단이다. 한국에서 기존 전환교통정책은 대상화물의 선정, 지원금의 지급대상과 산정기준 등에서 문제점이 나타나고 있다. 선진 외국의 전환교통정책을 살펴보면, 전환교통정책방향의 명확화, 실천 가능한 정책목표의 설정, 전환교통의 간접지원 강화 등의 시사점이 발견된다. 따라서 한국에서 전환교통정책을 활성화시키기 위해서는 정책의 수립단계부터 계획과 관리 측면에서 정책방향을 강구하는 것이 중요하다. 계획 측면의 전환교통정책의 수립방향은 전환교통정책 수립방향의 명확화, 운송수단별 사회적 비용 등 기초연구의 실시 및 철도시설정비방향의 설정 등으로 제시되고 있다. 한편 관리 측면에서 전환교통정책의 수립방향은 도로운송 지원정책과의 사전 상호조정 및 전환교통 대상화물의 전략적 관리 등으로 확인되어진다. 본 연구는 학술적인 정책연구의 특성이 강하다. 그래서 전환교통정책을 수립하는 데필요한 기본이론을 제공하며, 정책수립의 중요한 기본방향을 강구하는 데 연구의의가 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1000-1004
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• 1995

In the case of the external cylindrical grinding machine, the grinding mechanism can cause a wheel to vibrate due to a wheel cutter. This phenomena will bring about the unsymmetric wear up to high frequency without any relation of rotational speed. So far, when the grinding spindle is analyzed, it is assumed that a wheel is considered as lumped mass at the endof a beam. Nowadays, there is a tendency to use the wheel with a lsrge diameter or CBN wheel to achieve the high speed and accuracy grinding performance. Therefore, this kind of assumption is no longer valid. At the analysis of the grinding spindle, the parameter which dapends on the dynamic characteristics is a combination force between each part. For example, there is the tightness torque of a bolt and taper element in the grindle. In addition, the material property of the wheel can contribute the dynamic characteristics. This paper shows the mode participation of the shell mode of the wheel in the grindle and the dynamic characteristics according to the parameters which are the configuration of the flange and tightness torque of a bolt and taper. Modal parameter of the wheel, flange and the spindle can be extracted through frequency response function obtained by modal test. After that, by changing the tightness torque and kinds of wheel, we could accomplish the test in the whole combined grinding spindle. To perform modal analysis of vibration characteristics in the grinding spindle, we could develop the model of finite element method.