• 전기학회논문지
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• 제56권8호
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• pp.1418-1423
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• 2007

The topology of LLC half bridge resonant converter provides ZVS characteristic. The voltage stress and current stress are smaller than that of the general resonant converters. So the LLC HB resonant converter can be considered as a optimal circuit for the notebook computer adapter. In the adapter design, we should consider the weight, the size and the overheat of the adapter. Thus the higher efficiency is an essential particular. First of all, the optimal design of transformer is the most important facts. Some parameters should be considered in order to get the highest efficiency. The adapter is designed through the considering of these parameters including the PFC circuit as the pre-regulator. It converts AC line input into about DC 390V link voltage of the LLC HB converter input and the converter has 16V/90W ratings. The efficiency measured is about up to 93%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.206-208
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• 1995

Recently according to the increasing critical loads such as communication and life support systems stable power supplying becomes more and more important. Therefore it is indespensable to stabilize power source using these instruments - AVR(Automatic Voltage Regulator) or UPS(Uninterrutible Power Supply). This paper deals with ON-LNE UPS which is composed of PWM converter for AC-DC conversion. Using a PWM converter have advantages of low current harmonics and high power factor. In this paper ON-LNE UPS using PWM converter is proposed and its characteristics are investigated.

• Journal of Power Electronics
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• 제19권6호
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• pp.1403-1412
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• 2019

A coupled inductor-dual boost-inverter (CIDBI) with a differential structure has been presented for application to a micro-inverter photovoltaic module system due to its turn ratio of a high-voltage level. However, it is difficult to design a CIDBI converter with a conventional PI regulator to be stable and achieve good dynamic performance, given the fact that it is a high order system. In view of this situation, a sliding mode control (SMC) strategy is introduced in this paper, and two different sliding mode controllers (SMCs) are proposed and adopted in the left and right side of two Boost sub-circuits to implement the corresponding regulation of the voltage and current. The schemes of the SMCs have been elaborated in this paper including the establishment of a system variable structure model, selection of the sliding surface, determination of the control law, and presentation of the reaching conditions and sliding domain. Finally, the mathematic analysis and the proposed SMC are verified by experimental results.

• 한국자기학회지
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• 제5권5호
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• pp.606-609
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• 1995

Ferrite cores are often magnetized under DC-biased field because they have been intensively used in electronic circuits such as an inverter circuit and a switching regulator circuit. Thus we investigated the effects of DC-biased field on magnetic properties in the frequency range of DC-100kHz for two kinds of ferrite cores, TDK PC38 and TDK $H_{3}S$, which have different shapes of B-H loop from each other. The magnetic loss per cycle, W/f, in the $H_{3}S$ core decreased with increasing the strength of DC-biased field, although W/f in the PC38 core increased monotonically with DC-biased field. The observed decreasing tendency differs from the previous result for Si-Fe and ferrite cores, and can be attributed to decrease in eddy current loss as well as that in hysteresis loss.

• BMB Reports
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• 제52권1호
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• pp.64-69
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• 2019

The loss of skeletal muscle, called sarcopenia, is an inevitable event during the aging process, and significantly impacts quality of life. Autophagy is known to reduce muscle atrophy caused by dysfunctional organelles, even though the molecular mechanism remains unclear. Here, we have discuss the current understanding of exercise-induced autophagy activation in skeletal muscle regeneration and remodeling, leading to sarcopenia intervention. With aging, dysregulation of autophagy flux inhibits lysosomal storage processes involved in muscle biogenesis. AMPK-ULK1 and the $FoxO/PGC-1{\alpha}$ signaling pathways play a critical role in the induction of autophagy machinery in skeletal muscle, thus these pathways could be targets for therapeutics development. Autophagy has been also shown to be a critical regulator of stem cell fate, which determines satellite cell differentiation into muscle fiber, thereby increasing muscle mass. This review aims to provide a comprehensive understanding of the physiological role of autophagy in skeletal muscle aging and sarcopenia.

• 한국정보기술학회 영문논문지
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• 제10권2호
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• pp.1-13
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• 2020

This paper presents an emergency brushless synchronous generator having rotating exciter status monitoring and protection functions. For monitoring the rotating exciter status, a wireless rotor status detector and a digital AVR(Automatic Voltage Regulator), which has a wireless communication capability, are proposed. The proposed rotor status detector detects temperatures of exciter armature and main field windings and input voltage and current of the main field. Therefore, it is possible to protect the generator from the over-temperature of windings and detect the exciter bridge diode fault. Furthermore, the proposed digital AVR has rotor status monitoring and protection function, and remote generator tuning, wireless group parallel operation function. So the operator can efficiently operate the generator using a smartphone from a remote area.

• 한국정보기술학회 영문논문지
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• 제9권2호
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• pp.75-87
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• 2019

This paper presents a fully digital controlled power supply unit for the wireless controlled dimmable LED lighting system. The proposed power supply designed using a fly-back converter, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve a high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. For a wireless remote control function, the Zigbee modem is equipped in the proposed power supply. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the usefulness of the proposed power supply is verified.

• Current Research on Agriculture and Life Sciences
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• 제5권
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• pp.1-11
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• 1987

벼상자육묘(箱子育苗)에서 살균제(殺菌齊)와 생장조절제처리(生長調節劑處理)가 묘생육(苗生育) 및 생리장해(生理障害)에 미치는 영향(影響)을 구명(究明)코자 삼강(三綱)벼와 낙동(洛東)벼를 공시(供試)하여 시험(試驗)하였던 결과(結果)를 요약(要約)하면 다음과 같다. 살균제처리(殺菌齊處理)에서 삼강(三綱)벼는 Metalaxyl과 SF8002 처리구(處理區)가, 낙동(洛東)벼는 SF8002와 Metalaxyl처리구(處理區)가 초장(草長)과 3엽(葉) 및 4엽(葉)이 뚜렷한 신장교과(伸長效果)를 보였다. 건물중(乾物重)은 Metalaxyl구(區)가 가장 무거웠고 엽수(葉數)와 묘충실도(苗充實度)는 Dachigaren청리구(廳理區)가 양호(良好)하였으며, 살균제처리구(殺菌齊處理區)가 무처리(無處理)에 비(比)해 입고병발생(立枯病發生)이 적었다. 생장조절제처리구(生長調節劑處理區)에서 삼강(三綱)벼에서는 BA처리구(處理區)가, 낙동(洛東)벼에서는 GA，처리구(處理區)가 초장(草長)이 가장 길었으며, ABA(處理區)가 초장(草長)이 가장 작았고, ABA와 CCC처리구(處理區)가 신근발근력(新根發根力)이 왕성(旺盛)했다. 살균제(殺菌齊)+생장조절제처리구(生長調節劑處理區)에서 살균제(殺菌齊)+GA, 구(區)와 Metalaxyl+생장조절제처리구(生長調節劑處理區)가 초장(草長)이 가장 길었으며, Isoprothiolane+생장조절제처리구(生長調節劑處理區)가 초장(草長)이 가장 짧았다. Dachigaren+IAA 처리구(處理區)가 건물중(乾物重)과 묘충실도(苗充實度)가 양호(良好)하여 묘소질(苗素質)이 좋았으며, 살균제(殺菌齊)+생장조절제처리구(生長調節劑處理區)가 무처리(無處理)보다 입고병발생(立枯病發生)이 적었다. 또한 삼강(三綱)벼에서는 Metalaxyl+IAA 처리구(處理區)가 낙동(洛東)벼에서는 Dachigaren+IAA 처리구(處理區)가 지상부재생력(地上部再生力)이 양호(良好)했다.

• Journal of Power Electronics
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• 제16권3호
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• pp.1209-1217
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• 2016

This paper presents a novel charge pump scheme that combines the advantages of Fibonacci and Dickson charge pumps to obtain 30 V voltage for display driver integrated circuit application. This design only requires four external capacitors, which is suitable for a small-package application, such as smart card displays. High-amplitude (<6.6 V) clocks are produced to enhance the gate drive of a Dickson charge pump and improve the system's current drivability by using a voltage-doubler charge pump with a pulse skip regulator. This regulation engages many middle-voltage devices, and approximately 30% of chip size is saved. Further optimization of flying capacitors tends to decrease the total chip size by 2.1%. A precise and simple model for a one-stage Fibonacci charge pump with current load is also proposed for further efficiency optimization. In a practical design, its voltage error is within 0.12% for 1 mA of current load, and it maintains a 2.83% error even for 10 mA of current load. This charge pump is fabricated through a 0.11 μm 1.5 V/6 V/32 V process, and two regulators, namely, a pulse skip one and a linear one, are operated to maintain the output of the charge pump at 30 V. The performances of the two regulators in terms of ripple, efficiency, line regulation, and load regulation are investigated.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.132-136
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• 1996

A Study is a experiment which is figure out to aptimum discharge cutting condition of the surfaceroughness, electric discharging speed and electro wear ratio with Ton Toff and V(voltage) as an input condition according to the current(Ip) in an electric spark machine ; 1)Electrode is utilized Cu(coper) and Graphite. 2)Work piece is used the material of carbon steel. The condition of experiment is; 1)Current is varied 0.7(A) to 50(A). 2)Pulse time(Ton) is varied 3($\mu$s) to 240($\mu$s) and also Toff is varied 7($\mu$s) to 20($\mu$s). 3)The time of electric discharging to work piece in each time is 30(min) to 60(min) 4)After the upper side of work piece was measured in radius (5${\mu}{\textrm}{m}$) of syulus analyzed the surface roughness to made the table and graph of Rmax by yielding data. 5)Electro wear ratio is; \circled1Coper was measured cx-machining and post machining but the electronic baiance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume specific gravity and analyzed to made its table and graph on ground the data 6)In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V.R(Automatic Voltage Regulator). 7)The memory scope was sticked to the electric spark machine. 8)In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid, it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging According to above results, the surface roughness by the variation of electrodw and current was analyzed to compare KS(Korea Standards) It was decided the optimum condition of electric discharge cutting through analyzing the effect of electric discharge speed and electro wear ratio.