• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.2
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• pp.114-122
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• 2004

This paper presents a novel single-stage active-clamp type high frequency resonant inverter. The proposed topology is integrated full-bridge boost rectifier as power factor corrector and active-clamp type high frequency resonant inverter into a single-stage. The input stage of the full-bridge boost rectifier works in discontinuous conduction mode(DCM) with constant duty cycle and variable switching frequency. So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. By adding additional active-clamp circuit to conventional class-E high frequency resonant inverter, main switch of inverter part operates not only at Zero-Voltage-Switching mode but also reduces the switching voltage stress of main switch. Simulation results have demonstrated the feasibility of the proposed high frequency resonant inverter. Characteristics values based on characteristics estimation through circuit analysis is given as basis data in design procedure. Also, experimental results are presented to verify theoretical discussion. This proposed inverter will be able to be practically used as a power supply in the fields of induction heating applications, fluorescent lamp and DC-DC converter etc.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.601-608
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• 2005

This paper presents a novel single-stage high-power-factor electronic ballast for fluorescent lamps operating in critical conduction mode. The proposed topology is based on integration of boost converter as power factor corrector(PFC) and a half-bridge high frequency parallel resonant inverter into a single stage. The input stage of the boost converter is operating in critical conduction mode for positive and negative half cycle voltage respectively at line frequency(60Hz). So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. The simulated and experimental results for 100W fluorescent lamps operating at 42kHz switching frequency and 220V line voltage have been obtained. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, fluorescent lamp and DC-DC converter etc.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.9
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• pp.498-502
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• 1999

Harmonics and the reactive power related problems in the supply and demand side are increasing with the proliferation of nonlinear loads such as power converters in industrial applications. Filtering options such as passive, active and hybrid filters are countermeasures against these problems. In this study, a novel hybrid active filter topology with a new approach to enhance the system performance is presented. In this study, a novel hybrid active filter topology with a new approach to enhance the system performance is presented. The proposed topology comprised a parallel inverter and a hybrid active filter. It improves the system efficiency and reduces VA ratings, hence, overall filtering cost. The system operation, control and experimental verification on three phase rectifier and/or capacitor loads are presented.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.37-43
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• 2009

In this study, multi-channel digital hearing aid algorithm for low power system is proposed. First, MDCT(Modified Discrete Cosine Transform) method converts time domain of input speech signal into frequency domain of it. Output signal from MDCT makes a group about each channel, and then each channel signal adjusts a gain using LCF(Loudness Compensation Function) table depending on hearing loss of an auditory person. Finally, compensation signal is composed by TDAC and IMDCT. Its all of process make progress 16-bit fixed-point operation. We use fast-MDCT instead of MDCT for reducing system complexity and previously computed tables instead of log computation for estimating a gain. This algorithm evaluate through computer simulation.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1719-1721
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• 2005

현재 지구 환경 오염에 관한 관심이 증가하면서, 공해가 없는 자연 에너지원에 대한 연구가 많이 진행되고 있다. 그 중에서도 태양전지 분야중 염료감응형 태양전지(DSC)는 Si계 태양전지와 비교하여 낮은 제조비용등 여러 가지 이유로 최근 많은 연구가 진행되고 있다. 따라서 DSC 발전 시스템의 효율 향상이 요구된다. 본 연구에서는 태양전지 분야 중에서 독립적인 발전설비가 필요한 도서 및 산간 지역에 전력을 안정적으로 공급할 수 있는 소형발전용의 설비로 "전압 및 전류의 피드백을 통한 DSC Cell의 독립전원의 안정화"에 관해 연구하였다. DSC Cell측의 DC입력을 받아 Boost Converter로 승압 후 Full Bridge 인버터를 사용하여 단상 220V 60Hz의 상용전원으로 변환하였다. 여기서는 32Bit 마이크로프로세서인 DSP TMS320F2812의 A/D변환기능을 이용하여 Boost Converter의 스위칭과 Full Bridge 인버터의 스위칭을 제어하였다. 특히 TMS320F2812의 RTC(Real Time Clock)를 이용하여 출력전압의 안정성 향상에 주목적을 두었다. 실험결과 출력단에서는 220V 변동범위 0.2% 주파수 60Hz의 상용전원을 얻었으며, 프로그램의 개선을 통하여 출력전압의 변동범위를 감소시켜야 될 것이다.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.559-562
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• 2003

In this paper, we introduce a new method detecting thyristor faults of the power converter module in Control Rod Control System. When we control the currents in each coil of Control Rod Drive Mechanism by using the current control method, the current value can follow the current reference despite the faults like the missing phase or the diode acting. Comparing the fault current values with the normal current values, the bad transient characteristics of the abnormal current can make the operations of control rods incorrect. In this case, the information from the current trends cannot be enough to detect the fault occurrence in thyristors. Instead of the coil currents, the state of thyristors can be watched by measuring the coil voltages. In the existing system of Westinghouse type, the ripple detector takes charge of this task. But this detector has some shortcomings in the point of time for fault detection, we come to devise a new fault detection method solving the problems which belong to the ripple detector.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.685-689
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• 2009

Flash memory has several features such as low~power consumption and fast access so that there has been various research on using flash memory as new storage. Especially the Solid State Disk which is composed of flash memory chips has recently replaced the hard disk. At present, SSD adopts the multi-channel and multi-way architecture to exploit advantages of parallel access. In this architecture, data are written on SSD in a unit of a superblock which is composed of multiple blocks in which some blocks are put together. This paper proposes two schemes of selecting, segmenting and re-composing victim superblocks to optimize concurrent processing when a buffer flush occurs. The experimental results show that 35% of superblock- based write operations is reduced by selecting victims and additional 9% by composition of superblock.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.391-395
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• 2009

최근 한정된 자원으로 인한 에너지 수요가 증가하면서 에너지 절약 문제가 중요한 과제로 대두되었다. 본 논문에서는 효율적인 에너지 절약 문제를 해결하기 위한 방법으로 열 영상과 퍼지 제어 기법을 적용하여 실내 냉방 장치의 풍향과 풍속을 제어하는 방법을 제시한다. 본 논문에서는 실내 냉방 장치의 풍향과 풍속을 제어하기 위해 획득한 초기 열 영상을 색상 분포 영상으로 변환한다. 색상 분포 영상은 Red, Magenta, Yellow, Green, Sky, Blue의 온도 값을 가지는 RGB 값이며 각 색상은 $24.0^{\circ}C$에서 $27.0^{\circ}C$의 분포의 온도 값을 가진다. 본 논문에서는 색상 분포 영상을 좌에서 우로 5개의 계층 구간으로 분류하여 온도를 분석한다. 실내 공간의 색상 분포 영상을 분석하여 얻어진 각 계층 구간의 온도와 대기 중의 습도를 퍼지 소속 함수에 적용하여 구해진 결과 값을 비퍼지화 하고 최종적으로 풍향의 세기를 제어한다. 그리고 열 영상을 분석하여 풍향의 우선순위, 풍향의 지속시간을 결정한다. 제안된 방법을 $300{\times}400$ 크기의 열 영상을 대상으로 기존의 시스템과의 전력량 차이를 시뮬레이션 한 결과, 제안된 방법이 효과적인 것을 확인할 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.212-225
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• 2023

This study presents a modularized process of a hybrid renewable energy system that combines photovoltaic power and wind power to supply stable power in a unit area (1 km²). The water electrolysis process and fuel cells process also contributes to the supply of the stable power. The entire system can constantly supply power of 4.39 MW/km². Actual meteorological data is used for simulation.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.7
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• pp.476-487
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• 2007

Flash memory offers attractive features, such as non-volatile, shock resistance, fast access, and low power consumption for data storage. However, it has one main drawback of requiring an erase before updating the contents. Furthermore, flash memory can only be erased limited number of times. To overcome limitations, flash memory needs a software layer called flash translation layer (FTL). The basic function of FTL is to translate the logical address from the file system like file allocation table (FAT) to the physical address in flash memory. In this paper, a new FTL algorithm called an efficient and advanced space-management technique (EAST) is proposed. EAST improves the performance by optimizing the number of log blocks, by applying the state transition, and by using reallocation blocks. The results of experiments show that EAST outperforms FAST, which is an enhanced log block scheme, particularly when the usage of flash memory is not full.