• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.289-291
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• 2008

태양전지에 관한 많은 모델이 제안되어 왔으나 대부분은 특정 일사량에서 측정된 태양전지의 I-V 특성커브를 기준으로 보간법을 사용하여 운전점을 구하는 모델링 방식을 사용하고 있으며, 태양전지의 동특성 모델에 관한 연구는 매우 드물다. 효율적인 에너지 변환을 위한 고성능 전력변환기의 설계를 위해서는 태양전지의 정특성 및 동특성에 관한 정확한 정보가 요구된다. 태양전지의 정특성은 제조사에 의해 일반적으로 측정되어 공개되므로 용이하게 이해될 수 있으나 동특성은 그렇지 못하다. 본 논문에서는 임피던스 분광법(Impedance Spectroscopy)을 이용하여 태양전지 모듈의 동특성 모델을 개발하고, 개발된 모델의 유용함과 정밀함을 실험을 통해 검증 하였다. 개발된 동특성 모델은 정밀한 태양전지 시뮬레이션과 새로운 MPPT 알고리즘 개발에 이용될 수 있을 것으로 기대된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1607-1612
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• 2011

In this study, dynamic analysis of a proportional solenoid valve is performed, and an LQG/LTR controller with an integrator is designed to control the proportional solenoid valve. The dynamic characteristic of a valve is identified using experimental data by employing the frequency-domain modeling technique. The purpose of LQG/LTR control with an integrator is to enhance the system response and to improve the tracking accuracy for a complex input signal. Experimental tests are performed to verify the performance of the controller, and the results prove the high performance of the controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.518-523
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• 1995

To improve the set comfort of commercial vehicles in various road conditions, it is necessary to design a seat shock absorber which can avoid the vibration zone imposing the discomfort feeling and fatigue on drivers. Through the vibration and dynamic analysis, a shock absorber that has 4 steps of damping ability is developed. Dynamic characteristics analysis of the seat damper is performed considering each valve and oil path for the design purpose.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.85-90
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• 1997

In the stroke sensitive shock absorber, the oil path is formed along the internal cylinder surface to make the eli flow during piston's upper-lower reciprocation movement. With constraint to the conventional shock absorbers which show one dynamic characteristic curve, stroke sensitive shock absorber shows two kins of dynamic characteristic according to the stroke, In the study, analysis on the damping force generation process and dynamic behaviour characteristics of stroke sensitive shock absorber is performed, the valve characteristics being considered more precise information about design and damping performance analysis.

• Journal of the Korean Institute of Intelligent Systems
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• v.6 no.2
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• pp.57-71
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• 1996

차량 모델 비선형성의 주된 요인중 하나는 타이어의 비선형성이라고 할 수 있다. 타이어 모델도 간편화하기 위해 선형화된 타이어 모델을 적용할 경우에 저속 주행 또는 고속 주행이라고도 조향각이 적을 때는 문제가 없지만, 급격한 가감속과 과도한 조향각을 주었을 때는 타이어 미끄럼 각(Tire Slip Angle)이 급격히 변화되므로 선형화 된 타이어 모텔을 적용하지 못하게 된다. 그러므로 타이어와 지면 사이의 물리적 현상을 자세히 표현할 수 있는 비선형 타이어 모델을 적용하지 못하게 된다. 그러므로 타이어와 지면 사이의 물리적 현상을 자세히 표현할 수 있는 비선형 타이어 모델이 요구되어진다. 실험적 모델은 실제 차량의 실험 데이터를 바탕으로 커브 피팅(Curve Fitting)하여 타이어의 동특성을 표현하도록 모델링 하므로서 모델의 정확도를 높일 수 있는 반면 요구하는 계수들이 많아지게 되어 계산량이 증가되는 단점이 있다. 기존의 타이어 모델 연구 결과에 대해 분석하고, 관측 자료들을 바탕으로 FMFNN(Fuzzy Membership Function based Neural Network)을 이용한 함수 근사화로서 타이어 횡축력과 종축력의 모델링 방법을 제안하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.963-970
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• 2015

In this study, the pressurization characteristics of the small piezoelectric hydraulic pump for a brake system has been analyzed through modeling the full hydraulic pump components; the pump chamber, check valve, pump load, pump drive controller etc. To analyze the pressurization characteristics, the process of charging pressure in the chamber with stacked-layer piezoelectric actuator were firstly modeled. Secondly, the flow coefficient of the check valve in terms of valve opening has been calculated after computational fluid dynamics analysis, such as the pressure distribution around check valve and the flow rate, was conducted. Also the pump driving controller, which controls the input voltage to the actuator, was designed to make the load pressure follow the input pressure command. The simulation results find that it takes about 0.03ms to reach the operating load pressure required for the braking system. The simulation result was also verified through comparison to the result of the pump performance test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.321-322
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• 2006

In many manufacturing processes such as web formation, manufacturing of paper and nonwoven, fabric weaving, etc., planar sheets are transported and at the same time appropriate tension is imposed. The input material rolled up on beams is fed by unwinding the beam and the processed is then taken up on beams by winding it. While processed, the planar sheets are thrown under the processing load of impulse form, which causes irregular thickness of the processed sheet. To improve the quality of the product, a dynamic model is needed and the dynamic characteristics is to be analyzed by simulation. This study shows that density variation dynamics of the in-process-sheet in the machine direction can be described at each moment of disturbing impacts in forms of difference equations, while the impacts and tension, the time-dependency of the material properties were taken into account. Simulation showed the most serious variation of the density occurred in the process starting phase. The starting velocity curve with step form showed the least variation of the density. As the time order of the function of the starting velocity cure becomes higher, the density variation gets greater.