• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.286-286
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• 2009

A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of $5cm^2$. The passive stack has 12cells with an active area of $16cm^2$. When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.11
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• pp.23-29
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• 2008

This paper presents a new conceptual electromagnetic induction eddy current based stainless steel plate spiral type heater for heat exchanger or dual packs heater in hot water system boiler steamer and super heated steamer, which is more suitable and acceptable for new generation consumer power applications. In addition, an active clamping quasi-resonant PWM high frequency inverter using trench gate IGBTs power module can operate under a principle of zero voltage soft commutation with PWM is developed and demonstrated for a high efficient induction heated hot water system and boiler in the consumer power applications. This consumer induction heater power appliance using active clamping soft switching PWM high frequency inverter is evaluated and discussed on the basis of experimental results.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1929-1934
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• 2011

Recently the maximum speed becomes the most important performance in high speed train. But the speed up of train will not give the passenger good riding comfort. The semi-active suspension system by using variable damper with hydraulic solenoid valve is used to solve this problem. But the variable damper with hydraulic solenoid valve requires tank for supplying fluid. In this study, the MR(Magneto Rheological) damper was considered instead of hydraulic variable damper in order to improve riding comfort. Dynamic simulation was conducted for semi-active suspension system with MR damper was made by using Matlab-Simulink S/W. According to control strategy of MR damper for improving ride comfort in railway vehicle, The riding comfort of the railway vehicle with semi-active suspension system was analyzed and compared with conventional suspension system by using the program.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.94-102
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• 1995

The active control system of structural vibration using a hydraulic actuator is developed. The developed system consists of three parts : a hydraulic unit, an actuator unit and a control unit. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass giving anti-phase inertia force to the structure. It is experimentally confirmed that the vibration level of model structure is reduced to about 1/6 by the developed active control system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.284-285
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• 2008

For development of low fuel consumption vehicle, design of engine can he changed and it brings collateral effect. Abnormal vibration is one of bad effect of high efficiency engine and it can be got over by active engine mount system. For development of active engine mount system, an adequate experimental equipment is required which contain characteristic of real engine movement. To make adequate experimental equipment, regulated force vibrating system including characteristics of vehicle chassis is required.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.101-106
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• 2011

The failure of cooling system in Superconducting Fault Current Limiter(SFCL) increases the impedance of superconducting device, and due to malfunction of inner switches the SFCL opens the distribution system inadvertently when required to do so. In this paper, the ground fault and short circuit fault were classified as active failure and the open circuit fault was passive failure. A reliability model of SFCL considers the passive failure as well as active failure, and in the case study the reliability indices of distribution system are evaluated. It is possible that the reliability evaluation excluded passive failure makes the customers reliability seem so worse than it really was. Therefore, the reliability models of SFCL must include the active failure and passive failure together to evaluate the reliability of distribution system connected SFCL.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1161-1166
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• 1993

The performances of a vehicle active suspension system with an optimal variable structure controller are compared to those of passive suspension system and active suspension systems with sky-hook and optimal controllers. The quater car model has a 2 DOF which accounts for vertical motions of a sprung and a unsprung masses. The transient responses are analyzed when a vehicle passing through a bump with a constant speed and the frequency responses are analyzed for white noise input at wheel. Particulary, RMS responses are also analyzed. It is shown that the optimal variable structure controller gives better performance of the vehicle active suspensio system than an optimal and a sky-hook controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.437-441
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• 1997

In the conventional remote monitoring system, a user in front of a computer monitor can acquire only 2 dimensional visual information in a passive way. Thus, even thoght the user finds an interesting object from the video image, helshe can hardly acquire additional information on the object such as name. 311 shape, etc. In this paper, an active monitoring system that shows additional information on the selected object is proposed. The active remote monitoring system can calculate the 3D position of the object that is selected in the video images. Then, using the 3D position of the object, other information on the object can be retrieved from the database and shown on the screen. To calculate the 3D position of the object, 2 CCD cameras that can be tilted and panned using 3 stepping motors are used. The algorithm of 3D position calculation and the result of experiments are explained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1182-1194
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• 2004

This paper addresses the application of an active magnetic bearing (AMB) system to levitate the elevation axis of an electro-optical sight mounted on a moving vehicle. In this type of system, it is desirable to retain the elevation axis in an air-gap between magnetic bearing stators while the vehicle is moving. To eliminate disturbance responses, a disturbance observer based sliding mode control is developed. This control can decouple disturbance observation dynamics from sliding mode dynamics and preserves the robustness of the sliding control. The sliding surfaces are designed in the consideration of scattering of received image. The proposed control is applied to a 2-DOF active magnetic bearing system subject to base motion. Along with experimental results, the feasibility of the proposed technique is illustrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.274-279
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• 2000

Driving of the engine makes unbalance forces which induces vibration to the engine mount system. Active vibration control must be performed to reduce the vibration and the propagation of structure-born sound. In this study, the engine system is modeled as 3-dim. vibration system including flexible structures and an effective active noise control method is proposed. Also, appropriate actuator and sensor locations and types are selected. The miniature of the engine vibration system with multi-input multi-output is built and an active vibration control with multiple filtered-X LMS algorithm is applied to it. The applied control method was effective to reduce the transmitted vibration power through the rubber mount It showed the feasibility of the control of the engine vibration systems with flexible structures.