• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.199-200
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• 2011

Uninterruptible Power Supply(UPS) is largely divided into passive-standby, line-interactive and double-conversion methods. This paper proposes the double-conversion UPS for low cost and high performance. The proposed UPS are composed of PFC, inverter, battery charger and discharger. Finally, the validity of proposed UPS was verified by experiments.

• 공업화학
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• 제8권3호
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• pp.543-549
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• 1997

니켈(Ni)이 담지된 촉매상에서 이산화탄소와 부탄의 직접반응에 의한 합성가스와 탄화수소화합물의 생성을 검토하였다. $CO_2$와 $C_4H_{10}$의 반응에서 니켈 담지촉매는 백금 담지촉매와 유사한 활성을 나타내었으며, 부탄의 탈수소에 따큰 코크의 누적이 현저하게 나타났다. 담체로 알루미나나 Y형 제올라이트를 사용하면 일산화탄소와 수소가 주생성물이었다. 반면에 니켈을 ZSM-5형 제올라이트에 담지한 경우에는 생성물 중에 다량의 방향족화합물이 얻어졌다. Ni/ZSM-5, Ni/NaY 및 Ni/알루미나 촉매상에서 반응물 중의 이산화탄소/부탄 몰비의 증가와 함께이산화탄소의 전환율도 증가하다가 2이상에서 다시 감소하였다. 담체로 ZSM-5를 사용하고 이에 담지되는 니켈의 양을 다르게 하였을 때, 반응물의 전환율은 니켈금속의 담지량이 5wt% 부근에서 가장 높았다. 코크가 누적된 촉매상에 $CO_2$ 가스나 수증기를 흘리면 코크의 양은 감소하였다. 촉매상에 누적된 코크는 활성이 높은 상태로 결합되어 있으며, 표면의 활성탄소는 반응의 중요한 중간체로 작용하는 것으로 해석된다.

• 공업화학
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• 제9권4호
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• pp.497-503
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• 1998

알루미나에 담지한 귀금속 촉매를 이용하여 1.2-dichloroethane의 산화분해반응을 수행하였다. 실험결과 전환율은 Ru > Pt > Pd $${\sim_=}$$ Rh 순으로 높게 나타났으나, 완전산화 반응이 일어날 때의 주생성물인 $CO_2$로의 전환율 및 선택도를 기준으로 활성을 비교할 때 Pt/alumina가 Ru/alumina보다 활성이 높게 나타났다. $CO_2$ 및 vinyl chloride가 반응 주생성물로 검출되었는데, 반응 생성물 분포로부터 1.2-dichloroethane의 분해반응 경로는 1단계로 dehydrochlorination에 의해 vinyl chloride가 생성된 후 2단계로 vinyl chloride가 $CO_2$로 oxidation됨을 알 수 있었다. 염소를 포함하고 있는 반응 주생성물인 HCl의 영향을 살펴보기 위하여 반응물에 HCl을 첨가하여 반응을 수행하였는데 $300^{\circ}C$ 이하에서는 HCl이 촉매 표면에 흡착함에 따라 표면의 산도를 증가시켜 1.2-dichloroethane의 전환율은 증가하지만 $300^{\circ}C$ 이상에서는 HCl과 촉매 표면과의 상호작용이 약해져 전환율에는 큰 영향을 주지 않았다. 또한 촉매 표면에 가역적으로 흡착된 HCl은 1.2-dichloroethane의 $CO_2$로의 완전산화 반응을 방해함을 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.148-158
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• 2022

The electrochemical CO₂ reduction (ECR) to produce value-added fuels and chemicals using clean energy sources (like solar and wind) is a promising technology to neutralize the carbon cycle and reproduce the fuels. Presently, the ECR has been the most attractive route to produce carbon-building blocks that have growing global production and high market demand. The electrochemical CO₂ reduction could be extensively implemented if it produces valuable products at those costs which are financially competitive with the present market prices. Herein, the electrochemical conversion of CO₂ obtained from flue gases of a power plant to produce diesel and formic acid using a consistent techno-economic approach is presented. The first scenario analyzed the production of diesel fuel which was formed through Fischer-Tropsch processing of CO (obtained through electroreduction of CO₂) and hydrogen, while in the second scenario, direct electrochemical CO₂ reduction to formic acid was considered. As per the base case assumptions extracted from the previous outstanding research studies, both processes weren't competitive with the existing fuel prices, indicating that high electrochemical (EC) cell capital cost was the main limiting component. The diesel fuel production was predicted as the best route for the cost-effective production of fuels under conceivable optimistic case assumptions, and the formic acid was found to be costly in terms of stored energy contents and has a facile production mechanism at those costs which are financially competitive with its bulk market price. In both processes, the liquid product cost was greatly affected by the parameters affecting the EC cell capital expenses, such as cost concerning the electrode area, faradaic efficiency, and current density.

• Journal of Power Electronics
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• 제15권3호
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• pp.695-701
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• 2015

Uninterruptible Power Supplies (UPSs) can be largely divided into the passive-standby, line-interactive and double-conversion methods. This paper proposes a double-conversion UPS with a low cost and high performance. This single phase UPS uses a single-loop robust voltage controller and 1-switch voltage doubler strategy PFC. The proposed UPS is composed of a single phase PFC, a half-bridge inverter, a battery charger and a battery discharger. Finally, the validity of proposed UPS was verified by various experimental tests.

• 한국연소학회지
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• 제7권3호
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• pp.16-22
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• 2002

Combustion performance of an internally cycloned circulating fluidized bed for paper sludge was discussed through a series of batch type experiments. Operation parameters such as water content, feeding mass of sludge and secondary air injection rate were varied to find out the effect on the combustion performance, which was examined with carbon conversion rate and pollutant emission such as CO and NOx. A conventional solid fuel reaction was observed in the experiments of varying water content and feeding mass of the sludge, which is characterized with kinetic limited reaction zone, diffusion limited reaction zone and transition zone. Secondary air injection with swirl enhances the mixing of the gas phase as well as the solid phase, and improves combustion efficiency accompanied with higher carbon conversion rate and lower pollutant emission rate.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.236-245
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• 2000

A laboratory scale fluidized bed reactor was developed to treat the combustion characteristics of some fuels (wood, paper sludge, refuse derived fuel). The aims were to introduce the means of experiment and interpretation of the results and finally determine the particle characteristics on the pyrolysis and combustion process of the fuel. A single particle combustion process in the fluidized bed was closely observed. Understanding experimental facility characteristics and determining parameters were also carried out. The fuel combustion processes were observed by carbon conversion rate, recovery and mean carbon conversion time. They were estimated with the CO, $CO_2$ gas concentration monitored at the exit of the combustor. Fuel drying and pyrolysis process were governed by temperature distribution in the fuel particle. There was a significant overlap of the drying and devolatilization. However, transition process from devolatilization to char combustion seemed to be determined by mechanical solidity of the fuel particle after devolatilization process.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.83-84
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• 2014

This paper proposes the development of double conversion Uninterruptible Power Supply using 3-Level Converter/TNPC Inverter. The Rectifier of proposed system is operating not only 3-Level boost PFC but also battery discharger. The Inverter is converting DC voltage to AC voltage. And in terms of the efficiency, 3-Level TNPC inverter is improved compared to the origin 2-Level type. To verify the validity of proposed system, experiments were carried out.

• 한국응용과학기술학회지
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• 제13권2호
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• pp.77-84
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• 1996

Poly(vinyl acetate)와 poly(vinyl acetate-co-2-ethylhexyl acrylate)를 여러 조건에서 semicontinuous emulsion 중합으로 합성하였다. Overall conversion, emulsion 입자크기, pH, 점도 등을 합성한 두 emulsion polymer에 대해 측정하였다. Vinyl acetate monomer에 2-ethylhexyl acrylate를 도입함으로서 emulsion 입도, 점도, 중합 속도, 유리 전이 속도가 감소함을 확인하였다.

• 디지털콘텐츠학회 논문지
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• 제17권4호
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• pp.227-234
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• 2016

한자가 유입된 당시 한자의 원음도 함께 들어와서 현재 많은 한자들이 중국과 같은 한자에 같은 발음으로 사용하고 있으나 한국과 중국은 한자에 대한 발음이 서로 독립적으로 보존 및 변천되어 오늘날은 그 발음을 표기하는 방식이 서로 다르다. 본 연구는 중국 한자의 발음인 한어병음과 한국 한자발음을 구성하는 초성, 중성, 종성의 변화를 시스템으로 분석하여 중국어 발음과 대응되는 변환규칙을 생성함으로써 쉽게 중국어 발음을 학습할 수 있는 중국어규칙변환 교육시스템으로 설계 및 구현하였다. 본 연구는 중국어규칙변환 교육시스템을 웹으로 구현하였고, 앱등의 다양한 어플리케이션을 통하여 중국어를 학습하는데 도움이 되도록 하였다.