• 한국기계가공학회지
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• 제9권5호
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• pp.76-82
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• 2010

In this study, we carried out to evaluate the shock-proof of a large scale motor for the naval vessel using dynamic design analysis method (DDAM) and full transient dynamic analysis. Analytical models for main assemblies (motor frame, rotor and stator assembly) were consisted of the tetrahedral solid elements and the equipments which installed in the upper side of the motor were substituted the mass elements. And we also modelled resilient mounts of a motor using the beam elements with appropriate directional stiffness. The DDAM was conducted according to NRL memorandum report 1396 and the full transient dynamic analysis was performed applying directional triple half triangle shock wave to the motor using ANSYS 12. As a result, we could compare of the results according to each analytic method and find the motor to satisfy the design criteria of the maximum stress and deformation.

• 한국정밀공학회지
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• 제22권12호
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• pp.131-140
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• 2005

Responses of the cabinet of the reactor safety system under seismic leadings are analyzed, its dynamic characteristics and structural reliability being evaluated. Analyzed natural frequencies are compared with those measured from a resonance test. Structural safety of the cabinet is evaluated in consideration of the required response spectrums of the operation-base and safe-shutdown earthquakes. Transient responses of the cabinet are analyzed with input ground acceleration measured during the seismic test, accelerations being extracted at the locations of the main internal parts. The transient responses are compared with those from the seismic test, favorable results being shown.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2016년도 춘계학술대회
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• pp.302-304
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• 2016

The purpose of this paper is to draw comparison between the performance of ${\alpha}-{\beta}-{\gamma}$ filter and Kalman filter of a tracking module for ARPA system on board high dynamic warship. The comparison is based on the filters' capability to reduce residual error and maintain a stable transient response. The residual error is computed from the difference between the observed the predicted positions for the entire tracking period. The results indicate that the Kalman filter has a higher tracking accuracy compared to the optimal ${\alpha}-{\beta}-{\gamma}$ filter. However, both filters have a similar transient response.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.353-356
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• 2005

We developed a dynamic model of PEM fuel cell system which can analyze its transient response to dynamic load current. System components such as compressor, air cooler, humidifier, and stack were modeled based on their dynamic equations and performance maps by using Matlab Simulink platform. Through this simulation model, dynamic characteristics of fuel cell system including oxygen excess rat io, stack voltage, and system efficiency were shown. In addition to that, we briefly analyzed the humidity effect on cathode pressure and system efficiency, expecting that this model can be further used to optimize fuel cell system parameters just like operating pressure and temperature, humidity and oxygen excess ratio.

• 전산구조공학
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• 제10권3호
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• pp.125-131
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• 1997

대부분의 동적계는 기진력 및 계 인자들에 있어서 다양한 불확정 특성을 갖고 있다. 본 연구에서는 기진력의 불확정성과 계 인자들의 불확정성을 모두 갖는 선형 동적계에 대한 응답해석 과정을 제안하였다. 확률특성을 갖는 계 인자와 응답은 섭동법에 의해 모델링되었으며, 응답해석은 불규칙 진동 이론에 의하여 정식화 되었다. 또한 제안된 응답 모델에 의해 계산되기 어려운 응답의 평균에 대한 해석은 확률유한요소법을 사용하였다. 적용 예로서 정상 백색잡음 기진력을 받으며 불확정 질량과 스프링 상수를 갖는 1자유도계 문제에 대하여 과도응답을 계산하고, 그 결과를 수치 시뮬레이션 결과와 비교하여 그 타당성을 검토하였다.

• Journal of Power Electronics
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• 제13권6호
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• pp.991-999
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• 2013

In this paper, a fast transient buck converter using hysteresis PWM control is presented. The proposed control method is based on hysteresis control of the capacitor C voltage. This offers a faster transient response to meet the challenges of the power supply requirements for fast dynamic input and load changes. It also provides better stability and solves the compensation problem of the error amplifier in conversional voltage PWM control. Finally, the steady-state and dynamic operation of the proposed control method are analyzed and verified by simulation and experimental results.

• Structural Engineering and Mechanics
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• 제59권2호
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• pp.243-259
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• 2016

This research develops a finite element code for the transient dynamic analysis of tapered fiber reinforced polymer (FRP) poles with hollow circular cross-section and flexible joints used in power transmission lines. The FRP poles are modeled by tapered beam elements and their flexible joints by a rotational spring. To solve the time equations of transient dynamic analysis, precise time integration method is utilized. In order to verify the utilized formulations, a typical jointed FRP pole under step, triangular and sine pulses is analyzed by the developed finite element code and also ANSYS commercial finite element software for comparison. Thereafter, the effect of joint flexibility on its dynamic behavior is investigated. It is observed that by increasing the joint stiffness, the amplitude of the pole tip deflection history decreases, and the time of occurrence of the maximum deflection is earlier.

• Transactions on Control, Automation and Systems Engineering
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• 제4권4호
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• pp.296-304
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• 2002

A position tracking control schemes on the precise mechanical system in presence of nonlinear dynamic friction is proposed. A nonlinear dynamic friction is regarded as the bristle friction model to compensate effects of friction. The conventional sliding mode controller often has been used as a non-model-based friction controller, but it has a poor tracking performance in high-precision position tracking application since it completely cannot compensate the friction effect below a certain precision level. Thus to improve the precise position tracking performance, we propose the sliding mode control method combined with the friction-model-based observer having tunable structure of the transient response. Then this control scheme has a good transient response as well as the high precise tracking performance compared with the conventional sliding mode control without observer and the control system with similar type of observer. The experiments on the bali-screw drive table with the nonlinear dynamic friction show the feasibility of the proposed control scheme.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2879-2884
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• 2007

Dynamic responses of electrorheological (ER) fluids in steady pressure flow to stepwise electric field excitations are investigated experimentally. The transient periods under various applied electric fields and flow velocities were determined from the pressure behavior of the ER fluid in the flow channel with two parallel-plate electrodes. The pressure response times were exponentially decreased with the increase of the flow velocity, but increased with the increase of the applied electric field strength. In order to investigate the cluster structure formation of the ER particles, it was verified using the flow visualization technique that the transient response of ER fluids in the flow mode is assigned to the densification process in the competition of the electric field-induced particle attractive interaction forces and the hydrodynamic forces, unlike that in the shear mode determined by the aggregation process.

• Structural Engineering and Mechanics
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• 제13권6호
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• pp.695-711
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• 2002

Here, the dynamic response characteristics of thick cross-ply laminated composite cylindrical shells are studied using a higher-order displacement model. The formulation accounts for the nonlinear variation of the in-plane and transverse displacements through the thickness, and abrupt discontinuity in slope of the in-plane displacements at any interface. The effect of inplane and rotary inertia terms is included. The analysis is carried out using finite element approach. The influences of various terms in the higher-order displacement field on the free vibrations, and transient dynamic response characteristics of cylindrical composite shells subjected to thermal and mechanical loads are analyzed.