• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.237-240
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• 2004

For the paralleled operation of DC/DC converters, the current sharing between each modules is the most important for the reliability of the power system. Interleaving method is commonly used with many paralleling schemes for the reduction of the ripple in the output voltage of paralleled converters and there are many commercial IC for interleaving application appliable. But for all of them, it is impossible to detect the number of module in operating and then change the phase of them automatically. In this paper, a novel paralleling method is proposed for the converter parallel operation, which detects the number of modules in active and sets the phases of PWM signals applied to each modules autonomously. This can greatly improve the output voltage ripple and reliability of the system. The expandibility of modular number can be done very easily by just adding several parts.

• Journal of information and communication convergence engineering
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• v.18 no.3
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• pp.201-206
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• 2020

This paper presents a new method for controlling the current of lighting LEDs without current sensors. This method can be used as backup against LED current sensor faults. LED lighting requires a circuit with a constant current in order to maintain the same brightness when the ambient temperature changes. Therefore, we propose a new current estimation method to provide backup in case of current sensor faults based on the calculation of the inductor current. In the fabricated circuit, the average current changes from 144.03 mA to 155.97 mA when the ambient temperature changes from 0℃ to 60℃. The application of this study can enable the fabrication of a driving IC for LEDs in the form of a single chip without sensing resistors. This is expected to reduce the complexity of the peripheral circuit and enable precise feedback control.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.34-37
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• 2001

In this paper, we designed and implemented the 60W DC characteristic measurement system for semiconductor devices. The proposed system is composed of 2 SMU(Source and Measure Unit)s, 2 HPU(High power Unit)s, 2VSU(Voltage Source Unit)s, and 2 VMU(Voltage Measurement Unit)s. HPU can source/measure voltage from -200V to 200V and source/measure current from -3A to 3A within 60W. Experimental results show that the implemented system can measure the power devices such as power BJT, regulator IC, and voltage detector.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.16-18
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• 2006

This paper presents a sensorless speed control of Brushless DC motor using terminal voltage of one phase. Rotor position information is extracted by indirectly sensing the Back-EMF from only one of the three terminal voltages for a three phase BLDC motor. This is a advantage for the cost saving and size reduction. Also, it can be substituted for conventional Hall-IC or encoder applied to position control.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.496-502
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• 2006

In this paper, we studied the development of the electronic ballast for 250W MH (Metal-Halide) lamps. We were able to improve the input power factor by using a PFC IC. To provide the lamp with the rated voltage required, we used the buck-type dc-dc converter. The stress of the switching devices in the inverter could be reduced by this method. To eliminate the acoustic resonance phenomena of MH lamps, the voltage of the lamp added the high frequency sine-wave to the low frequency square-wave by using the full bridge typed inverter. We have developed a simple igniter using the L and C elements. We could control the dimness of the lamp by varying the output voltage of the buck converter. The buck converter output voltage could be controlled by using a microprocessor.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.409-412
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• 2007

A lot of research for system-on-panel(SOP) have been done to integrate display systems including data driver, gate driver, timing controller, DC-DC converter, and smart functions such as embedded touch screen, ambient brightness sensing and luminance control, finger printing on the glass. Recently, the cost of an one-chip driver IC with various functions has decreased rapidly, and new mobile display interface technologies have been introduced. So it is necessary to examine the feasibility of SOP for practical mobile applications. In this paper, we will re-examine LTPS technologies for mobile displays in terms of various aspects and discuss the practical limitations on SOP technology and future technology trend of mobile displays.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.27-32
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• 2015

A maximum power point tracking (MPPT) algorithm using fuzzy controller was considered. MPPT method was implemented based on the voltage and reference PV voltage value was obtained from Artificial Neural Network (ANN)-model of PV modules. Therefore, measuring only the PV module voltage is adequate for MPPT operation. Fuzzy controller is used to directly control dc-dc buck converter. The simulation results have been used to verify the effectiveness of the algorithm. The proposed method is compared with conventional PO(perturbation & observation), IC(Incremental Conductance) method. The nonlinearity and adaptiveness of fuzzy controller provided good performance under parameter variations such as solar irradiation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.902-905
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• 2006

This paper presents a new RF testing scheme based on a design-for-testability (DFT) method for measuring functional specifications of RF integrated circuits (IC). The proposed method provides input impedance. gain, noise figure. input voltage standing wave ratio (VSWR) and output signal-to-noise ratio (SNR) of a low noise amplifier (LNA). The RF test scheme is based on theoretical expressions that produce the actual RF device specifications by output DC voltages from the DR chip.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.277-278
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• 2014

본 논문은 저 대기전력의 구현이 가능하며 출력전압을 정확하게 제어할 수 있는 플라이백 컨버터 제어방식을 제안한다. 제안 방식은 모든 절연 형 컨버터에 적용 가능하고, 2차 측에 PFM(Pulse Frequency Modulation) IC를 위치시켜 정확한 출력전압 제어가 가능하다. 또한, 1,2차 측간에 신호 전달을 위하여 기존에 사용되는 TL431과 포토커플러가 아닌 Y-capacitor와 Low-Pass-Filter를 적용하여, 저 대기전력 구현이 가능하다. 제안방식의 타당성을 검증하기 위하여 이론적 해석과 시뮬레이션을 통하여 가능성을 확인하였다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.415-416
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• 2012

본 논문에서는 저가격형 PoE(Power over Ethernet)를 위한 새로운 부하분담기법을 적용한 스위칭 전원 회로를 제안한다. 기존의 PoE 전원회로는 Ethernet 채널 당 제한된 전력용량으로 인해 보다 큰 전력이 요구될 경우 채널별 DC/DC컨버터의 출력을 서로 병렬 접속하여 사용하고 있으며 각 채널별 부하를 동일하게 분담하기 위해 부하분담 IC 및 부가회로가 추가됨에 따라 회로 구조가 복잡하고 부피가 증대되는 단점이 있다. 제안된 PoE 전원회로는 이러한 문제를 해결하기 위해 병렬 연결된 채널 간 부하분담을 별도의 부가회로 없이 일정하게 제어할 수 있다. 제안 회로의 타당성 검증을 위해 이론적 분석 및 50W 급 시작품 제작을 통한 실험결과를 제시한다.