• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.762-765
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• 2005

본 연구에서는 유도 진동기의 파워 스펙트럼의 확산을 위한 LF2470 DSP기반 Hybrid Random PWM을 제안하였다. 제안된 방법은 Lead-Lag 랜덤 비트를 발생하기 위한 PRBS (Pseudo-Random Binary Sequence)와 PRBS와 논리적 비교를 위한 삼각파 랜덤 캐리어로 이루어진다. 또한 DSP에 의하여 랜덤 수 및 PRBS 그리고 3상 기준 정현파를 실시간으로 발생하며, DSP외부의 주파수 변조기 MAX038에 의하여 랜덤 주파수의 캐리어를 발생한다. 본 연구의 타당성 검증을 위하여 제안된 기법을 3상 유도전동기 구동장치에 적용하였으며, 종전의 방법과 전압 및 전류 그리고 전동기 소음 스펙트럼을 비교 검토하였다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.4-6
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• 2019

본 논문은 Modular Scalable Inverter System에서 큰 부피를 차지하는 인덕터를 저감하기 위한 방법을 제안한다. 최근 전력분야에서는 모듈형 전력변환 시스템을 사용함으로써 다양한 시스템에 필요한 전력을 공급하여 효율을 증가시키고 신뢰성을 높이는 방법들이 대두되고 있다. 하지만 모듈을 병렬로 사용하는 경우에는 모듈 간에 흐르는 순환 전류가 발생하게 된다. 이런 순환전류는 부하로 전력을 공급하지 않기 때문에 시스템 효율을 떨어트리고 전류제어 및 부하 분담을 방해한다. 따라서 병렬형 인버터에는 출력에 순환전류 저감을 위한 인덕터를 사용해야 한다는 단점이 있다. 모듈형 전력변환 장치에서 큰 크기의 출력 인덕터는 시스템 사이즈를 늘리고 비용을 증가시키고 전력밀도가 낮아지게 된다. 따라서 GaN HEMT (Gallium Nitride High Electron Mobility Transistor) 기반 인버터와 순환전류 저감 알고리즘을 사용하여 고속 스위칭을 함으로써 동일한 순환전류 저감 성능을 확보하지만 출력 인덕터의 크기를 줄이는 방안을 제시한다.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2119-2122
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• 2000

포항 방사광 가속기의 선형 가속기에서는 80-MW 클라이스트론 부하를 구동하기 위하여 최대 펄스 정격출력 200 MW(400kv 500A, 평탄도 4.4 $\mu s$)인 대출력 펄스 트랜스포머가 요구된다. 펄스 트랜스포머는 펄스 전원공급 장치(Modulator)로부터 대출력 부하(Klystron)로 펄스 에너지를 전달하며 임피던스 정합을 시키는 기능을 한다. 모듈레이터의 고전압 출력 펄스에서 RF 에너지를 발생시키는데 사용되는 유효 출력 에너지는 출력 펄스의 평탄부의 에너지에 해당된다. 그러므로, 펄스 트랜스포머는 빠른 상승시간을 가지는 것이 요구된다. 빠른 상승시간을 얻기 위하여 누설자속, 분포용량이 작게 되도록 설계하여야 한다.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.197-199
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• 2005

The Cold cathode fluorescent lamp (CCFL) are widely used to illuminate the liquid crystal display(LCD). Ballasts are required for CCFL because the lamp need high starting voltage and behave negative dynamic resistant characteristics in the desired region of operation. Dimming methods of CCFL are used to pulse frequency modulation(PFM) or pulse width modulation(PWM). In this paper, CCFL driving and control circuit is designed by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output voltage current. The validity of this study is confirmed from the simulation and experimental results.

• Convergence Security Journal
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• v.8 no.2
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• pp.27-34
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• 2008

In this paper, we designed and implemented mobile object automatic system based on senor networks for telematics. For developing this system, we gather the various sensing data through wireless communication method using zigbee sensor networks and analyze them in monitoring equipment. And we enable the driver to recognize the car state information on the whole by interfacing analyzed data to telematics unit. And, we implemented automatic controller that can control temperature and humidity in car automatically by actuating air conditioner based on the data that was monitored throughout temperature sensor, humidity sensor and brightness sensor based on sensor networks.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.241-243
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• 2003

By development of power electronics technology, the increasing of inverter's switching frequency lead to the development of speed control technology of induction motor. But the surge voltage including harmonic component in output waveform can cause the motor to generate power losses, torque ripple, acoustic noise and oscillation. This paper is analyzed the characteristics for switching surge of adjustable speed drive and is presented the problem by inverter.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.229-234
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• 1999

This thesis presents the design method using CAE(Computer Aided Engineering) with the consideration of reliability for optimal gear driving system. The validity and feasibility of the proposed method are verified by the application to transmission of machine tool. The reliability and life analysis is based on the two-parameter Weibull distribution lives of the gears and bearings. Ninety-percent of reliability life is the life of the component or system in million output rotations or hours at which ninety percent of identical components or system would survive under the given loading conditions.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.561-566
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• 2003

Research and development project for the gearboxes of Korea High Speed Train is being run as one of the 'G7 Project' to achieve the Technical Independency in the area for the High Speed - High Load Gearboxes. Executing this project we domesticate the technologies for Design, Analysis, Manufacturing and Testing. Acquired high-technologies can be applied not only to the Rolling Stocks, but also to other Industrial Areas including the Cars and Aerovehicles. The prototypes had been tested on the roller rig and are being tested on the railway.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.399-403
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• 2002

The transmission system of high speed train serve in the severe condition compared with those of other trains, namely, they have to transmit high power to run with high speed and they have to make maximum use of the limited space. To clarify the strength of gear for Korea High-Speed Train, a bending fatigue test of gear specimen is performed and compare with actual gear's. From this result, specimen test is useful to infer S-N curve and endurance limit of actual gear that much time and expense are consumed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.343-350
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• 2002

The structural stability of pressure housing of SMART CEDM forming pressure boundary must be evaluated. In this paper, the stress and thermal analyses of the upper pressure housing of CEDM are performed for design pressure, hydraulic test pressure and thermal loading. Finite element and boundary condition were generated from the model which is made by I-DEAS program and the stress and thermal analyses were performed by ANSYS Program. The upper Pressure housing was analysed using 2D axisymmetric model because it is symmetry about an axis. The stress values obtained by analysis were compared with the stress intensity limit of ASME and KEPIC MNB standard.