• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.355-357
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• 1999

Single-Phase multi-level AC-DC converter that is composed of diode bridge and switch is proposed. The number of the supply current level is depending on the individual current level of the converter. A converter circuit, the number of the level is equal to $2^{M+1}-1$, where M is the number of Switching Converter. The proposed circuit has converter with 31 current levels. When the number of current level is increased, smoother sinusoidal waveform can be obtained directly and it is possible to control the supply current almost continuously from zero to maximum without generating high voltage step changes as pulse with modulation technology. The technique illustrates its validity and effectiveness through the PSIM.

• Journal of Biosystems Engineering
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• 제33권4호
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• pp.248-252
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• 2008

An experiment was conducted in order to investigate gasification characteristics of rice husks in a fixed bed, which was a pre-step to design a continuous gasification system. Two air supply levels for gasification were chosen and their effects on the producer gas amount and producer gas composition were discussed. The main components of the producer gas were CO, $CO_2$, $O_2$, $H_2$ and THC (Total HydroCarbon). As airflow rate decreased, more producer gas was produced. The peak amount of CO, $H_2$ and THC were 28%, 7.5% and 0.68% in volume when constant airflow rate of $3.36\;m^3/s$ was used in the batch operation. About 4.5 kg of ash (9%) and condensed water including tars of 6 kg (11%) were produced from 50 kg rice husks in the gasification. Excluding the byproducts, all rice husks seemed to be transformed into producer gas. This gasification study was conducted prior to developing a continuous gasification system for biomass including agricultural byproducts.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권4호
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• pp.123-129
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• 2003

We propose a high voltage dc-dc converter for a CW (continuous wave) $CO_2$ laser system using a current resonant half-bridge inverter and a Cockcroft-Walton circuit. This high voltage power supply includes a 2-stage voltage multiplier driven by a regulated half-bridge series resonant inverter. The inverter drives a step-up transformer and the secondary transformer is applied to the voltage multiplier. It is highly efficient because of the reduced amount of switching losses by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up secondary transformer combined with the Cockroft-Walton circuit. We obtained a maximum laser output power of 44 W and a maximum system efficiency of over 16%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1821-1823
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• 2003

We propose a high voltage dc-dc converter for CW(continuous wave) $CO_2$ laser system using a current resonant half-bridge inverter and a Cockcroft-Walton circuit. This high voltage power supply includes a 2-stage voltage multiplier driven by a regulated half-bridge series resonant inverter. The inverter drives a step-up transformer and the transformer secondary is applied to the voltage multiplier. Thus, it has high efficiency because of the less switching losses by virtue of the current resonant half-bridge inverter, and also compact size, small parasitic capacitance in the transformer stage owing to the low number of a winding turn of the step up transformer secondary by combining with Cockroft-Walton circuit. We could be obtained the maximum laser output power of 44 W and the maximum system efficiency of over 16 %.

• 전자공학회논문지SC
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• 제43권2호
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• pp.33-39
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• 2006

본 논문에서는 휴대용 적외선 야시경의 소형 경량화 및 저전력을 위한 전자회로부를 설계하였다. 설계한 전자회로부는 전압자동변환부와 전원공급부로 구성한다. 전압자동변환부는 배터리, 스위치부, 승압부, 전압선택부 등으로 구성한다. 전원공급부는 고광원 감지회로, 배터리 전압감지회로, 적외선 발광회로, 연결감지회로, 공급제어회로 등으로 구성한다. 설계한 전자회로부의 성능은 AN/PVS-14에 비하여 소모전력 및 상온 연속사용 시간에서 우수하였다.

• 한국생물환경조절학회:학술대회논문집
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• 한국생물환경조절학회 1997년도 봄 심포지움 및 학술논문발표요지
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• pp.23-27
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• 1997

Bio-Green(B.G.) functional water was manufactured by Kyungwon Enterprise Co. through a series of processes ; water longrightarrow ultra-purification longrightarrow adding catalysts longrightarrow energy imprinting fermenting with energized water + zeolite and others + photosynthetic bacteria in fermenter longrightarrow filtering. Control(0), 5 or 10 liters of B.G. functional water were supplied to the orchard soil under canopy of 10 year old 'Tsugaru'/M26 apple trees on March 20, May 20 and June 20, 1995, respectively. Some orchard soil characteristics, not only pH, but also Ca and Mg of exchangeable cations were increased by supply with B.G. functional water. However, P$_2$O$_{5}$, K, and B contents were not influenced by the treatment. At harvest time soluble solid content of flesh and anthocyanin of fruit skin were increased by the treatment. B.G. functional water treatment showed higher root activities, and photosynthesis of leaves than that of control. Also B.G. functional water treatment showed higher Ca content in fruit skin and flesh tissues, whereas not affected N, K, and Mg contents. During storage at 4$^{\circ}C$ cold room, the more volume of B.G. functional water supply showed lower bitter pit symptom. Respiration and ethylene evolution in fruit were decreased, while fruit firmness increased by the treatment during storage.e.

• 반도체디스플레이기술학회지
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• 제17권2호
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• pp.53-56
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• 2018

In this paper, a CMOS bandgap voltage reference that is not sensitive to changes in the external environment is presented. Large OLED display panels need high supply voltage. MOSFET devices with high voltage are sensitive to the output voltage due to the channel length modulation effect. The self-cascode circuit was applied to the bandgap reference circuit. Simulation results show that the maximum output voltage change of the basic circuit is 77mV when the supply voltage is changed from 10.5V to 13.5V, but the proposed circuit change is improved to 0.0422mV. The improved circuit has a low temperature coefficient of $9.1ppm/^{\circ}C$ when changing the temperature from $-40^{\circ}C$ to $140^{\circ}C$. Therefore, the proposed circuit can be used as a reference voltage source for circuits that require a high supply voltage.

• 한국환경과학회지
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• 제23권9호
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• pp.1643-1654
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• 2014

The university is one of the main energy consumption facilities and thereby releases a large amount of greenhouse gas (GHG). Accordingly, efforts for reducing energy consumption and GHG have been established in many local as well as international universities. However, it has been limited to energy consumption and GHG, and has not included air pollution (AP). Therefore, we estimated GHG and AP integrated emissions from the energy consumed by Seoul National University of Science and Technology during the years between 2010 and 2012. In addition, the effect of alternative energy use scenario was analysed. We estimated GHG using IPCC guideline and Guidelines for Local Government Greenhouse Inventories, and AP using APEMEP/EEA Emission Inventory Guidebook 2013 and Air Pollutants Calculation Manual. The estimated annual average GHG emission was $11,420tonCO_{2eq}$, of which 27% was direct emissions from fuel combustion sectors, including stationary and mobile source, and the remaining 73% was indirect emissions from purchased electricity and purchased water supply. The estimated annual average AP emission was 7,757 kgAP, of which the total amount was from direct emissions only. The annual GHG emissions from city gas and purchased electricity usage per unit area ($m^2$) of the university buildings were estimated as $15.4kgCO_{2eq}/m^2$ and $42.4tonCO_{2eq}/m^2$ and those per person enrolled in the university were $210kgCO_{2eq}$/capita and $577kgCO_{2eq}$/capita. Alternative energy use scenarios revealed that the use of all alternative energy sources including solar energy, electric car and rain water reuse applicable to the university could reduce as much as 9.4% of the annual GHG and 34% of AP integrated emissions, saving approximately 400 million won per year, corresponding to 14% of the university energy budget.

• 에너지공학
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• 제16권1호
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• pp.22-31
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• 2007

본 논문에서는 전력수급기본계획에 열병합발전설비의 최적용량을 반영할 수 있는 방법론을 개발하였으며 이에 따른 효과를 분석하였다. 이를 위해 열병합발전의 계획발전원가를 새로이 산정하여 심사곡선법(Screening Curve Method : SCM)을 이용한 정태적 최적 전원을 구성하였다. 이때, 열병합발전은 전기와 열을 생산하는 것이 가장 중요한 특징이므로 이를 고려할 수 있도록 열병합발전의 전기용량과 열용량을 모두 고려할 수 있는 계획발전원가를 도출하였다. 또한, 심사곡선법을 적용시키기 위한 부하지속곡선의 경우도 열병합발전의 특징을 고려하여 전기 및 열 부하지속곡선을 구성하여 적용하였다. 이때, 현재 수립된 전력 수급기본계획을 최대한 수정하지 않는 범위 내에서 열병합발전설비를 반영하도록 하였다. 열병합발전 건설계획을 반영한 계획안의 타당성을 증명하기 위해서 열병합발전 건설계획을 반영한 계획안과 전력수급기본계획을 비교 하였다. 즉, 발전량 기대치를 산출하여 발전원별 연료소비량 및 환경에 미치는 영향을 도출함으로써 열병합발전의 반영에 대한 효율성을 입증하였다.

• 한국환경농학회지
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• 제26권1호
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• pp.1-6
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• 2007

본 연구에서는 바이오가스의 연소엔진을 이용한 에너지 전환시에 발생되는 $NO_x$와 CO의 배출특성을 분석하고 나아가 배출계수를 산정하고자 하였다. 바이오가스의 주성분인 메탄을 70%로 한 합성가스를 이용하여 실험한 결과 연소엔진의 표준상태에서 $NO_x$와 CO가 각각 4 ppm과 100 ppm의 배출농도를 나타내었고, 이는 1.29g/MMBtu와 30.86 g/MMBtu의 배출계수 값을 산정할 수 있었다. 바이오가스의 주성분인 메탄을 60%로 한 약간의 과잉공기의 상태에서는 $NO_x$와 CO가 각각 2 ppm과 200 ppm의 배출농도를 나타내었고, 이는 정격 조건에 비해 투입열량이 적어져 연소온도의 저하로 인하여 열적 반응에 의해 생성되는 $NO_x$는 줄고, CO는 증가함을 알 수 있었다. 미국 EPA의 배출계수를 비교하기 위하여 투입된 연료의 열량을 기준으로 비교해 볼 때 본 연구의 결과가 $NO_x$의 경우 근사한 값을 보여 주었고, 이는 국내 바이오 가스 연소시의 오염배출계수로 잘 적용 가능함을 보여 주었다. 본 연구에서 사용한 가스엔진이 오염배출 측면에서 대기 환경보전법상의 배출 허용기준 내에서 가동됨을 알 수 있었고, 가동조건에 따라 연소온도를 증가시킴으로서 CO의 발생을 저감시킬 수 있으리라 사료된다.