• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1116-1117
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• 2007

In this paper, the control method of maximum power point tracking (MPPT) using the duty ratio control of buck-type dc/dc converter is presented for seaflow generation system. The advantage of the proposed MPPT method is that characteristics of seaflow generator(SG) with respect to seaflow speed, required in the conventional MPPT method, are not needed. Also, due to using the SG output power as a control parameter, neither characteristics of the seaflow speed nor measurements of the rotational speed of the generator are required. Thus, there are advantages that seaflow generation system having features of lower cost and complexity, and higher reliability can be designed. In this paper, Seaflow generation system using the buck-type dc/dc converter is proposed and the effectiveness of the MPPT algorithm is confirmed by matlab simulink.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.168-174
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• 2001

In this paper, a new space vector RPPWM (Random Position PWM) is proposed. In the proposed RPPWM, each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the randomization of the PWM pulses, we can obtain the effects of spread spectra of voltage, current as in the case of randomly changed switching frequency. To verify the validity of the proposed RPPWM, simulation study was tried using Matlab/simulink. The main model described in Simulink block diagrams includes the space vector modulation block, pulse position randomization block, inverter block, 3 phase induction motor block, and so on. By the simulation study, the harmonics of the output voltage, and the current of inverter are predicted in different PWM methods- SVPWM, LLPWM, proposed RPPWM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.572-573
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• 2005

Discharge of the flat lamp lighting source research are requested very much. For improving brightness. life time. efficiency of flat lamp and plasma diagnosis of the flat lamp lighting source to understand property of lighting source is very important. When a distance of discharge electrode is 5.5mm and width is 16.5mm. we measured electron temperature and electron density measured with single Langmuir probe in flat lamp. We tested the discharge from 100 Torr to 300 Torr pressure. The pulse type was rectangular with frequency 20kHz and duty ratio was 20%. In result. electron temperature decreases and electron density increased as increase the gas pressure and electron temperature decreases and electron density increase as increase the voltage.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1410-1412
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• 2005

A novel dimming algorithm for the electronic ballast of the electrodeless lamp is proposed. The proposed algorithm is based on the burst dimming method and controls the duty ratio for the two switches of the electronic ballast by pulse width modulated signal. The preposed algorithm was implemented by a fully digital circuit using EPLD device. To verify the validity of the proposed algorithm, the implemented control circuit was applied to the electronic ballast for a 100W electrodeless fluorescent lamp. As a result, the wide illumination dimming range from 5% to 100% was obtained.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1416-1418
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• 2005

This paper presents a new hybrid control method of asymmetrical half-bridge converter(AHBC) with low voltage stresses of the diodes and interleaved PFC(power factor correction). The proposed new control scheme can observe variation of secondary diodes voltage stresses by variation of duty ratio and then decide the control portions which are asymmetrical control and PFM(Pulse Frequency Modulation). Therefore, the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes, low conduction loss according to the low voltage drop and wide zvs range by load variation. Through simulation results, the validity of the proposed control scheme is demonstrated.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.325-327
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• 1995

A new gate drive circuit of classic converter for a switched reluctance motor is presented. Conventional gate drive circuit usually consists of the isolated power supplies and signal transferring devices for isolation, such as photo coupler, pulse transformer, and gate drive chips. The proposed gate drive circuit consists of resistors, capacitors, and zenor diodes without isolated power supplies, that make the drive circuit simple and reduce the material cost. The operational modes are classified and analyzed. The characteristics of the phase current and the gate signal of upper switches is investigated with the variation of duty ratio through the experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.375-378
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• 2005

Voice Coil Motor is used linear motion actuator system that require precision positioning control. In order to control precision positioning of voice coil motor, Mathematical model of voice coil motor is needed. Mathematical model is obtained by combining voice coil motor's equation of motion with the equation of circuit and characteristic of voice coil motor. The induced model can predict output displacement according to duty ratio and amplitude. The model is verified by experimental test. Simulated results have tracking errors of less than 10 percent of experimental results.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.237-238
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• 2009

본 연구에서는 이온에너지와 박막 표면 거칠기와의 관계를 신경망을 이용하여 모델링하였다. Pulsed 플라즈마 증착장비를 이용하여 상온에서 실리콘 나이트라이드 (SiN)을 증착하였다. 바이어스 전력과 duty ratio는 각각 $40{\sim}100W$와 $30{\sim}90%$로 변화하였다. 이온에너지 정보는 비침투식 이온에너지 분석시스템을 이용하여 수집하였다. 신경망의 성능은 유전자알고리즘을 이용하여 최적화시켰다. 최적화한 모델은 이온에너지의 영향을 고찰하였다. 모델로부터 고 이온 에너지는 저 이온에너지가 높은 조건에서 증가시킬 때에 표면 거칠기를 보다 작게 한다는 것을 알 수 있었다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.15-16
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• 2016

This paper proposes an isolated DCDC converter that consists of unregulated LLC resonant converter and non-isolated synchronous buck converter for battery charger of energy storage systems application. The unregulated converter operates as transformer with fixed duty ratio and switching frequency. The synchronous buck converter is installed in the output of the LLC resonant converter. And the converter charges and discharges the battery by controlling a current of battery. The proposed converter can get the high efficiency by separating function. This paper explains design of an unregulated converter and synchronous converter.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.204-205
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• 2016

Human power is not dependent on other energy sources, but rather is a source of power for ourselves. Human power, the cleanest energy in the world, can be our future. Therefore, we should be interested in sustainable alternative energy. This paper solves the uneven power generation by utilizing the energy storage capability of the flywheel. Therefore, it improved the efficiency by 5% compared to the existing generation method. DC generators produce power at variable speed operation. The constant voltage was generated from the DC-DC converter to the duty ratio control. Therefore, the charging efficiency is improved by 5% by the constant voltage charging of the battery. And it can suppress the decrease of the output due to the circulation current due to the deviation of the output voltage in parallel operation of the pedal generator.