• Journal of Information Display
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• 제4권4호
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• pp.13-18
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• 2003

One of the most important issues in AC PDP is the improvement of luminous efficiency. One possible method for achieving this aim is by increasing Xe partial pressure in discharge gas mixture. The increase of Xe ratio, however, causes the driving voltage to rise, even if brightness is increased. In this study, a new electrode shape is proposed. A test panel fabricated by using a new electrode shows that efficacy has improved by 25 % and sustain voltage has decreased by 20 % compared with the conventional structure.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.257-260
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• 2002

In this paper, the circuit of AC Choppers for $CO_2$laser Power Supply are proposed and investigated. IGBT-controlled ac voltage regulators, operating at high frequency chopping mode. Chopping-to-supply duty ratio plays an important role in terms of laser output. Laser input energy is varied by controlling the leakage transfomer used with the proposed system. This improved circuit employs a 3 electrode-type and Ring Blower. This improved circuit system has many advantages compared with the conventional SMPS such as simple design requirment, easy implementation, high reliability, low switching loss, and consequently high efficiency. As a result, the maximun output was 16W at duty-ratio of 92%, total gas mixture of $CO_2$: $N_2$: He = 1 : 9 : 15, total pressure of 15torr.

• 전력전자학회논문지
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• 제16권5호
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• pp.415-429
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• 2011

본 연구에서는 출력이 직렬 연결된 단상 quasi Z-소스 AC-AC 컨버터를 제안하였다. 제안된 시스템은 단상quasi Z-소스 AC-AC 컨버터 2대의 입력 단을 병렬로 연결하고 출력 단을 직렬로 연결한 구조로 되어 있으며, 역상 모드와 동상 모드 별 전류 흐름과 출력전압의 형성 과정을 나타내었다. DSP로 제어되는 실험 시스템을 제작하여 PSIM시뮬레이션 결과와 비교 분석하였다. 그 결과 각 모드별로 듀티 비를 제어하여 원하는 출력 전압을 벅-부스트 할 수 있었다. 컨버터 1대가 단독으로 운전한 경우에 비하여, 각각의 모드에 대하여 부하 저항의 증가에 따른컨버터 효율과 입력 역률을 제안된 방법에 의하여 개선할 수 있었다. 또한 역상 모드의 경우, 일정 부하에서 컨버터의 효율과 입력 역률을 각각 10[%]와 35[%]정도 개선하였으며, 특히 부하 저항이 변동하는 과도상태에서도 일정한 출력 전압을 유지할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.356-361
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• 2005

In this paper, a new scheme of current programmed control for three phase PWM AC-AC converter is presented. Compared to duty-ratio voltage control, current programmed control has several advantages such as reduction of system order and inherent current protection. By considering only the magnitude components, the same scheme in the DC-DC converter can be extended to the three phase PWM AC-AC converter. Sensing the output voltage and the inductor current, an error signal will be generated by comparing the output voltage magnitude with a reference value. Then the error signal will be processed by a PI compensator to generate the current command. The converter switches will the change the state by a periodic clock pulse or at the instants when the inductor current magnitude reaches the current command. As an example case, the buck converter is treated. The converter analysis is carried out by applying the complex DQ circuit transformation to obtain basic physical insight into the converter operation and to establish some important characteristic equations for control purpose. The simulation with Simplorer shows the validity of the proposed scheme and the experimental results support the verification of the design.

• 한국안광학회지
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• 제19권3호
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• pp.345-351
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• 2014

목적: 각 사위 그룹에서 가입렌즈에 따른 조절반응량과 근거리 수평사위도의 변화를 측정하여 자극 AC/A비와 반응 AC/A비를 조사하였다. 이에 자극 AC/A비와 반응 AC/A비를 비교 분석하여 임상에서의 양안시 검사 및 처방시에 유용한 자료로 제시하고자 한다. 방법: 평균 만 $20.89{\pm}1.92$세, 81명을 대상으로 주시거리 40 cm에서 개방형 자동굴절계(Nvision-K 5001, Shin nippon)와 수정된 토링톤 시표(MIM card; Muscle Imbalance Measure card, Bernell)를 이용하여 양안시 상태에서 조절반응량과 근거리 수평사위도를 측정하였다. 그리고 측정된 값을 토대로 자극 AC/A비와 반응 AC/A비를 경사 AC/A법으로 계산하였다. 결과: 주시거리 40 cm에서 조절반응량은 외사위 그룹이 $1.92{\pm}0.26$ D로 가장 크고, 정위 그룹 $1.72{\pm}0.26$ D, 내사위 그룹 $1.62{\pm}0.42$ D 순으로 작아졌고, 근거리 수평사위도의 변화폭은 내사위 그룹이 $23.24{\Delta}$로 가장 크고, 정위 그룹 $19.76{\Delta}$, 외사위 그룹 $15.14{\Delta}$ 순으로 작게 나타났다. 가입렌즈에 따른 자극 AC/A비와 반응 AC/A비의 차이는 외사위 그룹에서는 -2.00 D 렌즈를 가입하였을 때, $1.72{\Delta}/D$로 가장 컸고 내사위 그룹에서는 +1.00 D 렌즈를 가입하였을 때 $3.43{\Delta}/D$로 가장 크게 나타났다. 외사위 그룹에서 -2.00 D, -1.00 D 렌즈를 가입하였을 때, 내사위 그룹에서는 +3.00 D, +2.00 D, +1.00 D, -1.00 D 렌즈를 가입하였을 때 각각 통계적으로 유의한 차이를 보였다. 결론: 자극 AC/A비와 반응 AC/A비를 비교하였을 때, 외사위 그룹에서는 (-) 렌즈를 가입하였을 때의 차이가 더 크고, 내사위 그룹에서는 (+) 렌즈를 가입하였을 때의 차이가 더 크게 나타났다. 또한 내사위 그룹의 자극 AC/A비와 반응 AC/A비의 차이가 외사위 그룹의 차이보다 더 크게 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.60-62
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• 2005

This paper describes a feasibility analysis result of STATCOM application for the Jeiu-Haenam HVDC system. The Jeju-Haenam HVDC system is one of the typical HVDC system interconnected with the low short-circuit-ratio AC system, which is vulnerable to the commutation failure due to the AC voltage variation. STATCOM has been considered as an effective reactive-power compensator to increase short-circuit-ratio of the interconnected AC system. In this study, a simulation model of Jeju-Haenam HVDC system with STATCOM was developed using PSCAD/EMTDC. The developed simulation model was utilized to analyze the dynamic performance analysis of Jeju-Haenam HVDC system with STATCOM. The analysis results show that STATCOM can improve the dynamic performance of Jeju-Haenam HVDC system, such as load-change recovery performance and fault recovery performance.

• Journal of Plant Biotechnology
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• 제49권1호
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• pp.90-98
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• 2022

This study was performed to determine the optimal ratio for preparing an extract comprising the Ecklonia cava and Hizikia fusiformis complex as a therapeutic material for alleviating inflammatory respiratory diseases. First, to examine the optimal ratio for preparing the complex (SD-EH), Ecklonia cava and Hizikia fusiformis extracts were used; four extracts with different mixing ratios were prepared. The effects of the SD-EH extract on MUC5AC mRNA expression in PMA-treated NCI-H292 cells were analyzed; it was confirmed that the MUC5AC expression was significantly reduced after treatment with the SD-EHA-001 (E(100) : H(0)), SD-EHB-001 (E(90) : H(10)), SD-EHC-001 (E(80) : H(20)), and SD-EHD-001 (E(70) : H(30)) extracts. Western blotting was used to determine whether the SD-EH extract affects the expression levels of COX-2 and MMP-9 in PMA-treated A549 cells. The protein expression levels of COX-2 and MMP-9 were significantly lower (p < 0.001) in the cells treated with the SD-EHC-001 (E(80):H(20)), SD-EHD-001 (E(70) : H(30)), and SD-EHE-001 (E(60) : H(40) extracts than in the cells treated with PMA alone. The SD-EHC-001 (E(80) : H(20)) extract markedly downregulated the expression levels of MUC5AC, COX-2, and MMP-9. Therefore, the SE-EH extract may serve as a potential therapeutic agent for treating inflammatory respiratory diseases.

• 전기학회논문지
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• 제61권10호
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• pp.1432-1441
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• 2012

In this study, an improved LCCT(Inductor-Capacitor-Capacitor-Trans) Z-source inverter(Improved LCCT ZSI) with characteristics of Quasi Z-source inverter(QZSI) and LCCT Z-source inverter(LCCT ZSI) is proposed. The proposed inverter can also reduce the voltage stress and input current/capacitor voltage ripples compared with conventional LCCT ZSI and Quasi ZSI. A two winding trans in Z-impedance network of the conventional LCCT ZSI is replaced by a three winding trans in the proposed inverter. To verify the validity of the proposed inverter, a DSP controlled hardware was made and PSIM simulation was executed for each method. Comparing the current and voltage ripples of each method under the condition of input DC voltage 70[V] and output AC voltage 76[Vrms], the input current and capacitor voltage ripple factors of the proposed inverter were low as 11[%] and 1.4[%] respectively. And, for generation of the same output AC voltage of each method, voltage stress of the proposed inverter was low as 175[V] under the condition of duty ratio D=0.15. As mentioned above, we could know that the proposed inverter have the characteristics of low voltage stress, low ripple factor and low operation duty ratio compared with the conventional methods. Finally, the efficiency according to load change/duty ratio and the transient state characteristics were discussed.

• Carbon letters
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• 제11권1호
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• pp.28-33
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• 2010

In this study, $TiO_2$-Activated carbon (AC) complex fibers were prepared by electrospinning for the synergetic effect of adsorption and degradation of organic pollutant. The average diameter of these fibers increased with increasing the amount of AC added, except for 1AC-TOF (AC$/TiO_2$ =1/40 mass ratio). After calcinations at $500^{\circ}C$, long as-spun fibers were broken and their average diameter was slightly decreased. The resultant fibers after calcination had rough surface and sphere shapes like a peanut. From XRD results, it was confirmed that as-spun fibers were changed to anatase $Ti_O2$ fiber after calcinations at $500^{\circ}C$. The prepared $TiO_2$-AC complex fibers could remove procian blue dyes by solar light irradiation with high removal property of 94~99%. The PB dye was rapidly removed by adsorption during the initial 5 minutes. But after 5 minutes, dye removal was occurred by photodegradation. In this study, the most efficient AC/$TiO_2$ ratio of $TiO_2$-AC complex fibers was 5/40, showing the synergetic effect of adsorption and photodegradation. It is expected that the $TiO_2$-AC complex fibers can be used to remove of organic pollutants in water system.

• Journal of Power Electronics
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• 제18권6호
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• pp.1642-1649
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• 2018

A single-stage flyback LED AC-DC converter based on primary-side control under constant current mode is proposed in this study. The proposed converter features low total harmonic distortion (THD) and high power factor (PF). It also consists of a zero-crossing distortion compensation circuit and a variable duty ratio control compensation circuit to deal with the line current distortions caused by fixed duty ratio control. The system model and layout are built in Simplis and Cadence, respectively. The feasibility and performance of the proposed circuit is verified by designing and fabricating an IC controller in the HHNEC $0.35{\mu}m$ 5 V/40 V HVCMOS process. Experimental results show that the PF can reach a level in the range of 0.985-0.9965. Moreover, the average THD of the entire system is approximately 10%, with the minimum being 6.305%, as the input line voltage changes from 85 VAC to 265 VAC.