• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.46-50
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• 2002

In other to evaluate the static and dynamic stiffness of machine tool structure, the accuracy and error from experimental methods are studied in this paper. The F.E.M., impulse tests and exciter tests are performed for the general simple structure whose exact solution can be obtained. So that the parameter and dynamic compliance can be got. From the result, the variation of natural frequency can be verified from the static preload. Further more the relationship of identify and difference for compliance and direction is presented in the exciting direction and measurement direction.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.452-456
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• 2006

The critical speeds and mode shapes are most important to determine the behaviors of rotor in designing rotating machinery. As the capacity and span of turbine-generator increases, the turbine-generator system is composed of many components such as bearings, pedestal, turbine and hood and so on. Also, it is getting flexible and has many critical speeds. Especially, as the characteristics of bearing-pedestal are very complicated, they affect the entire vibration characteristics of turbine-generator system. In this paper, it is observed how to determine the equivalent dynamic stiffness of bearing-pedestal by analytical and experimental method.

• 소음진동
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• 제10권5호
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• pp.819-829
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• 2000

Dynamic Characteristics of two different types of ER(electro-rheological)mounts ; flow and shear mode types are analyzed and compared. As a first step, field-dependent Bingham models of a chemically treated starch/silicone oil-based ER fluid are empirically identified under both flow and shear mode conditions. The models are them incorporated to the governing equation of the corresponding mode ER mount. For the reasonable comparison between two ER mounts, electrode parameters such as electrode gap are designed to be same. Dynamic stiffness and displacement transmissibility of each ER mount are evaluated in frequency domain with respect to the intensity of electric filed. In addition, vibration control capability of each ER mount is investigated in both frequency and time domains by employing the skyhook controller.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.750-755
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• 2012

In this study we conduct the optimal spot-weld layout design of vehicle body structure considering dynamic stiffness and side impact. We conduct both linear static analysis and nonlinear analysis with a baseline model to verify the process. 13 design variables will be selected for the effect analysis. Then, topology optimization is conducted to each selected design variable. The design constraints are formulated to improve the dynamic stiffness and side impact performance. Objective function is to set the density of weld component. Optimal spot-weld layout design are compared with the baseline model to show the improvement.

• 반도체디스플레이기술학회지
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• 제10권4호
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• pp.15-20
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• 2011

The lithography system installed inside precision industry's (e.g. TFT-LCD) production factories are increasing in size, thereby increasing its dynamic load along with it. Such condition causes vibration within the area where the system is installed, which then negatively affects the production line to produce defective products. To prevent this type of situation, the facilities should adopt dynamic design that considers the lithography system's dynamic load. This study predicts the maximum value allowed for dynamic stiffness (which is a ratio of vibration response against a single unit of the dynamic load) of the lithography system and explains the result of its application on actual structures inside the facilities.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.355-360
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• 2001

By using Frenet formulation and Timoshenko beam theory, the partial differential equations of motion are derived for a helical spring having a doubly symmetrical cross section subjected to the pre-load axially. These equations of motion are solved to give the dispersion relationship and dynamic stiffness matrix is assembled. Natural frequencies are obtained from the receptance of the system. The results of the dynamic stiffness method are compared with those of the transfer matrix method from published examples and finite element method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.792-796
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• 2013

A practical process to optimize engine mounts on construction equipment is presented in this research. Transmitted force from the engine is estimated by using stiffness of the mount rubber which varies with frequency, amplitude and pre-load, and by the engine excitation force that comes from piston mass and gas pressure and so on. The transmitted force is measured through TPA(Transfer Path Analysis) and is then compared with the estimated force. The optimum mount position and stiffness are solved using MATLAB. The result shows the improvement on engine mount vibration.

• 소음진동
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• 제10권1호
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• pp.153-159
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• 2000

This paper presents a new method for including the dynamic stiffness of the stationary parts in rotordynamic analysis. As a consequence of the support dynamics, critical speeds are varied and/or additional critical speeds are introduced. Therefore, dynamic effects of the support are often significant in high speed turbomachinery, but most of analysis has considered the support as a rigid body or a simple structure. The proposed method is based on the coupled characteristics of the driving point and transfer frequency response functions of the support system to model the equivalent spring-mass series in finite element analysis. To demonstrate the applicability of the simulation procedures provided, it is applied to the rotor model of the double suction centrifugal pump. Results of the suggested equivalent-support rotor model including coupled effects agree well with the entire pump model.

• 한국정밀공학회지
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• 제12권7호
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• pp.99-106
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• 1995

Frequency response functions are of great use in dynamic analysis of structural systems. The present paper proposes an efficient method for computation of the frequency rewponse functions of linear structural dynamic models with a sparse, non-proportional damping matrix. An exact condensation procedure is proposed which enables the present method to condense the matrices without resulting in any errors. Also, an iterative scheme is proposed to be able to avoid matrix inversion in computing frequency response matrix. The proposed method is illustrated through a numerical example.

• 한국전자통신학회논문지
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• 제18권2호
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• pp.259-268
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• 2023

본 논문에서는 2.4GHz 밴드 무선 접속 기술을 2.4/5GHz 이중대역을 지원하는 기술을 이용하여 유선의 한계성을 극복할 수 있는 무선 서비스 제공으로 무선 공공서비스의 품질을 향상시키고자 한다. 무선 CCTV 구축시 발생되는 유지 보수 비용을 절감 시키고, 기존 유선 CCTV와 연동 가능해져 CCTV를 이용한 A/V 감시시스템 서비스 영역을 확대에 대해 연구한다.