• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.387-389
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• 2006

The LCD TV has many variable functions for consumer. Low temperature driving below minus 20 degree is also one of key functions. Since LCD is not self-luminance device, it is needed backlight system. Recently EEFL(External Electrode Fluorescent Lamp) widely substitutes for CCFL(Cold Cathode Fluorescent Lamp). It is more cheaper, higher efficiency, and easy to drive parallel connection compared to CCFL. In this paper, several conditions for low temperature driving of EEFL are investigated and a new boost-half bridge inverter for low temperature driving is proposed. Mode analysis is described and experimental results is represented to verify validity of the proposed inverter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1963-1965
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• 1998

In this paper, a new simplified configuration for a multi-level PWM inverter is proposed. The proposed inverter consists of an auxiliary circuit with one switching device, and 3 phase full-bridge inverter. The proposed inverter, in spite of reduction of the switching devices, offers characteristics similar to the NPC(Neutral - point - clamped)- PWM inverter. Also, since the reduction of the switching devices, the control strategy is simplified. And switching loss is reduced. In addition to, it is possible that reliable DC level voltage than former multi-level inverter. And load power application is same to conventional NPC-PWM inverter. The performance of the system is verified by simulation. In this paper, show the simulation result of the single phase full bridge inverter application.

• Interaction and multiscale mechanics
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• 제3권4호
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• pp.321-331
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• 2010

A new technique is proposed for bridge structural damage detection based on spatial wavelet analysis of the time history obtained from vehicle body moving over the bridge, which is different from traditional detection techniques based on the bridge response. A simply-supported Bernoulli-Euler beam subjected to a moving spring-mass unit is established, with the crack in the beam simulated by modeling the cracked section as a rotational spring connecting two undamaged beam segments, and the equations of motion for the system is derived. By using the transfer matrix method, the natural frequencies and mode shapes of the cracked beam are determined. The responses of the beam and the moving spring-mass unit are obtained by modal decomposition theory. The continuous wavelet transform is calculated on the displacement time histories of the sprung-mass. The case study result shows that the damage location can be accurately determined and the method is effective.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.43-44
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• 2010

본 연구는 사장교에 적용이 용이하도록 프리캐스트화한 FRP-콘크리트 합성 바닥판 개발에 대한 것이다. 개발된 바닥판에 대해서 구조상세 별로 성능실험을 완료한 후, 실제 중차량이 통과하는 공사용가교 상에 시험시공을 수행하였으며 구조적 성능 및 현장 적용성을 살펴보았다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.354-359
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• 2012

A transformerless converter suitable for multiphase drive application is presented in this paper. The topology employs a cascaded H-bridge rectifier as the interface between the grid and multi inverters which drive the multiphase motor. Compared with the conventional structure, the new topology eliminates the input transformer and also has the advantages such as four quadrant operation, simple configuration, low cost, high efficiency, and so on. The control strategies for the grid-side cascade H-bridge rectifier and the motor-side inverter are studied accordingly. Based on the multi-rotational reference frame, modular control scheme is developed to regulate the multiphase drive system. Simulation results show the proper operation of the proposed topology and the corresponding control strategy.

• Interaction and multiscale mechanics
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• 제1권3호
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• pp.357-368
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• 2008

The result of damage detection from on-site measurements is commonly polluted by unavoidable measurement noises. It is widely recognized that this side influence could be reduced to some extent if the sensor placement was properly designed. Although many methods have been proposed to find the optimal number and location of mono-type sensors, the optimal layout of multi-type sensors need further investigation, because a network of heterogeneous sensors is commonly used in engineering. In this paper, a new criterion of the optimal placement for different types of sensors is proposed. A corresponding heuristic is developed to search for good results. In addition, Monte Carlo simulation is suggested to design a robust damage detection system which contains certain redundancies. The validity of these methods is illustrated by two bridge examples.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.451-460
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• 2003

In this paper, high speed fiber optic sensor weigh-in motion (WIM) system is proposed. Bragg gratings which have several advantages such as good reproducibility and good multiplicity compare to other optical fiber sensors are used for the system. Fabry-Perot filter for the signal process, which cannot be used in the high speed measurement because of the limitation in fast operation of PZT, is excluded. A new signal processing system which employs bandwidth filter is proposed and bridge type new sensor package design is also proposed. Design of the mold supporter is modified to round shape and then supporting points do not change. The data from the fiber sensors show identical and linear behavior to the axle weight. The proposed fiber optic WIM system is tested in the laboratory and experimented with actual trucks. The new concept of calibration is introduced and calculated by the experiments. The calibrated weight data show good approximations to real axial weights regardless the velocities of the truck.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.254-258
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• 2001

This paper proposes a new induction heating system composed of a hyristor PWM rectifier with a resonant commutation circuit. The operation of proposed system as first analyzed by a theoretical approach with equivalent circuits. And its verification was performed by computer simulations with EMTP. The proposed system can provide a solution for the power factor problem of the existing high-power induction heating system. which uses the line-commutated thyristor bridge in rectifier side.

• 대한토목학회논문집
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• 제29권2A호
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• pp.109-118
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• 2009

이 연구에서는 CFT부재를 거더로 사용하는 신형식 강합성 교량 시스템 개발을 최종목표로 하고, CFT부재의 휨거동 특성을 규명하기 위한 부재실험을 수행하였다. 실험체는 충전재 강도 및 합성조건 변화 등 설계에 영향을 미치는 주요 매개변수를 고려하여 제작하였고, 휨재하 실험의 결과분석을 통해 CFT부재가 갖는 내력성능을 효율적으로 설계에 반영하기 위한 방안을 고찰하였다. 충전강관은 중공강관에 비해 휨강도 및 연성이 크게 증가함을 확인할 수 있었으며, 콘크리트의 취성적 재료 특성이 강관의 구속효과로 보완되는 결과를 확인하였다. 내부 전단연결재를 둠으로써 충전재와 강관 사이의 미끄러짐을 억제하여 완전합성단면으로 거동하였고, ㄱ형 전단연결재의 보강재 효과가 휨내력 증가에 다소 기여하고 있음을 알 수 있었다.

• 한국구조물진단유지관리공학회 논문집
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• 제9권3호
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• pp.129-138
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• 2005

본 논문은 사장교에서 모니터링 시스템을 통해 획득한 가속도 자료를 이용하여 케이블 관리기준 장력을 결정하기 위한 방법을 제시한다. 현재 한국의 많은 장대교량에 모니터링 시스템이 설치되어 있다. 모니터링 시스템은 교량의 이상현상이나 손상을 진단하고 관리주체에 경고하기 위해 설치된다. 사장교에 있어서는 그 기하학적인 형상 때문에 케이블 장력이 교량 이상징후의 중요한 지시가 될 수 있다. 만약 케이블 장력관리치가 너무 높거나 또는 너무 낮게 설정되면, 모니터링 시스템은 교량의 이상징후를 적절하게 경고하지 못할 것이다. 일반적으로, 관리치는 경험이나 공학적 판단에 의해 결정된다. 그러나 본 논문에서는 케이블 장력에 대한 확률분포모형과 신뢰성 해석에 기초한 새로운 케이블 장력관리치 설정에 대한 방법을 제시한다. 제안된 방법은 적용성 검토를 위하여 실제 콘크리트 사장교에 적용되었다.