• 한국소음진동공학회논문집
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• 제14권10호
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• pp.1035-1040
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• 2004

The vibration of an electric hand grinder originates from the motor, gear, bearing, and fan. Its excessive vibration can be harmful to workers. To reduce the vibration of an electric hand grinder. frequency analysis for the vibration signals of a running electric hand grinder and modal test for the each part were done. The results show that the vibration is due to the resonance of the case. To remove the resonance, the case structure was modified and the bearing cap was replaced on a basis of the results of the rotor dynamic analysis using SAMCEF. As a result, the vibration of the electric hand grinder was reduced greatly.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.1-6
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• 2011

This paper proposes a new design method for electric scooter which can maximize the power efficiency at the given driving condition. The proposed method is designed with the electric and mechanical parameters and driving dynamics. These values are extracted from the dynamic and mathematical equations of the scooter. For validation, numerical simulation results are presented in this paper. As a result, the scooter achieved over 80% efficiency at 360 rpm at 1.42kw load. It is clear that the proposed method was verified through a 1.42kw numerical model.

• 한국유체기계학회 논문집
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• 제12권4호
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• pp.54-62
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• 2009

The feedwater heaters are Critical components in a nuclear power plant. As the operation years of heaters go by, the maintenance costs required for continuous operation increase. When the carbon steel components in nuclear make contact with running fluid, the wall thinning caused by FAC (flow accelerated corrosion) can be generated. Local wall thinning is inevitable at the area around wet steam entrance to be attacked due to the long term operation. Sometimes the shell with thinned wall is eventually ruptured. To identify the relationship between the local wall thinning and fluid behavior of the feedwater heater, the practical data of a plant, which were based on ultrasonic thickness measurement tests, were analyzed and CFD(Computed Fluid Dynamics) analyses were performed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.113-118
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• 2005

Maglev vehicles, which are levitated and propelled by electromagnets, often run on elevated flexible guideways comprised of steel, aluminum and concrete. Therefore. an analysis of the dynamic interaction between the Maglev vehicle and the flexible guideway is needed in the design of the critical speed, ride, controler design and weight reduction of the vehicle. This study introduces a dynamic interaction simulation technique that applies structural dynamics. Because the proposed method uses FEM, it is useful to calculate the deformation of the elevated flexible guideway, the dynamic stress, and the motion of the vehicle. By applying the proposed method to an urban transit Maglev vehicle, UTM01, the dynamic response is simulated and validated. From the result of the study, we concluded, that the dynamic interaction between the maglev vehicle and the flexible guideway is possible.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.1115-1120
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• 2005

characteristic of wear between wheel and rail is important factor of judgement to maintenance. KHST is optimized on an exclusive rail, UIC60. but also KHST is running on the variety existing line as well as KS50N, KS60 et,c. Hail profile of KS50N is dissimilar to DIC60. So we can predict that characteristic of wear is embodied also different. In this paper. we deduced the force and point of contact position between wheel and rail through multi-dynamics analysis and predicted wear of wheel and rail through contact problem analysis. we used simplified theory of kallker on contact problem, and Predicted the wear phenomenon of wheel using archard wear equation about each condition.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.522-529
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• 2006

Running train is one of the most main factor for railway bridge vibration. The repeated forces with equidistant axles cause the magnification of dynamic responses which relates with maintenance of the track structure and structure-borne noises. The noise problem is one of the most important issues in services of light rail transit system which usually passes through towns. The noise of railway bridges can be divided into the noise from track-vehicle system and structure-borne noises. In the present study, The vibration and noise of the LRT bridge will be investigated with utilizing dynamics responses from moving train as input data for noise analysis.

• 한국철도학회논문집
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• 제10권1호
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• pp.22-28
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• 2007

During the passage of the train, the railway bridge undergoes vibration and noise. The noise of railway bridge can be occurred from various sources. The wheel-rail contact, noise from machinery parts, structural-borne noise, pantagraph noise and aerodynamic noise of the train work in combination. Running train is one of the most important factors for railway bridge vibration. The repeated forces with equidistant axles cause the magnification of dynamic responses which relates with maintenance of the track structure and structure-borne noises. The noise problem is one of the most important issues in services of light rail transit system which usually passes through towns. In the present study, The vibration and noise of the LRT bridge will be investigated with utilizing dynamics responses from moving train as input data for noise analysis.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.92-99
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• 2001

This paper presents a simulation study using a robust controller to improve the roll stability of a vehicle. The controller is designed in the framework of an output feedback H$_{\infty}$ control scheme based on the 3DOF linear vehicle model, solving the mixed-sensitivity problem to guarantee the robust stability and disturbance rejection with respect to parameter variations due to laden and running vehicle conditions. In order to investigate the feasibility of the active roll control system in a real car, its performance is evaluated by simulation in a 10DOF full vehicle model with actuator dynamics and tire characteristics.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.558-565
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• 1999

Rubber wheel-type AGT has two major kinds of bogie; one is the bogie type and the other and passenger loads. This paper deals with the statics analysis for two types of bogie frame subjected to combined external forces, as well as independent ones specified in UIC 515-4. Furthermore, the dynamics analysis is performed under vibrational loading conditions so as to compare dynamic characteristics, Numerical results by using commercial packages, Ⅰ-DEAS and NASTRAN show that maximum stresses do not exceed the yielding level of material used for both bogies. From an overall viewpoint of strength, the bogie type turns out to be superior to the steering type except the case of a lateral loading. It is also observed that the steering type shows a be stiffened. It is strongly anticipated that vibrational fatigue analysis should be carried out under realistic loading conditions closely matching to situations such as running surface and lateral clearances along the guideway.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.303-308
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• 2008

Directly modulated fiber-optic links generally suffer higher link loss and larger signal distortion than externally modulated links. These result from the electron-photon conversion loss and laser modulation dynamics. As a method to overcome the drawbacks, we have experimentally demonstrated the RF performance of directly modulated, ultra-strong injection-locked gain-lever distributed Bragg reflector (DBR) lasers. The free-running DBR lasers exhibit an improved amplitude modulation efficiency of 12.4 dB under gain-lever modulation at the expense of linearity. By combining gain-lever modulation with ultra-strong optical injection locking, we can gain the benefits of both improved modulation efficiency from the gain-lever effect, plus improved linearity from injection locking. Using an injection ratio of R=11 dB, a 23.4-dB improvement in amplitude response and an 18-dB improvement in spurious-free dynamic range have been achieved.