• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1055_1056
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• 2009

본 논문은 신.재생 에너지원 중 태양광을 이용한 소용량의 가정용 및 건물용 태양광 발전 시스템인 단상 계통연계형 인버터의 출력전류 고조파 발생에 대한 연구로서 상용제품에 대한 실험 결과를 제시하고, 이를 모의한 실험을 통하여 단상 계통연계형 인버터의 출력전류 고조파 억제를 위한 연구 근거로 제시한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.251-254
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• 2006

2000 년대 초반부터 글로벌화에 따라 화상회의 시스템이 정부와 기업에 중요한 업무지원도구로 확산이 되고 있다. 그 동안은 화상회의는 기업이라는 제한된 울타리에서 1:1 또는 다자간의 회의를 위한 도구로 만족을 하였지만 점차 화상회의를 상업용, 가정용으로 적극적인 활용을 모색하는 추세이다. 또한 기존의 인터넷, 모바일 등을 이용한 비즈니스 모델은 발전의 한계점에 도달하였으며, 고객들의 새로운 요구에 부응하기 위하여는 화상회의를 이용한 비즈니스 모델의 출현이 요구되는 시점이다. 본 연구에서는 화상회의를 이용한 비즈니스의 확산을 위하여, 화상회의 비즈니스 모델의 구조를 설계하였다. 또한 설계를 적용할 수 있는 환경연구로서, e-커머스에 대응한 화상회의 상거래, 즉 v-커머스를 지향한 기술 및 서비스 구성, 비즈니스 모델의 유형과 고객가치속성, 모델의 구성요소, 적용사례 등을 제시하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.131-137
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• 1998

The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuated on the variation of insolation, temperature and load. Photovoltaic system needs an inverter which can interface the dc output power of solar cell with the residential ac load. The inverter has to supply a sinusoidal current and voltage to the load and the utility line with a high power factor. This paper proposes an utility interactive photovoltaic system designed with a step-up chopper and a PWM voltage source inverter. The step-up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power points of solar cell without any influence on the variation of insolation and temperature. The voltage source inverter operates in a manner that its output voltage is in phase with the utility voltage. The inverter supplies an ac power with high factor and low level of harmonics to the load and the utility power system.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.182.1-182.1
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• 2010

현재 전 세계적으로 가장 널리 개발하고 보급되어지고 있는 풍력산업의 시장 규모는 매년 확대되고 있다. 특히 소형 풍력발전 시스템은 낙도 등의 전력 공급이 어려운 지역에 경제성 있는 전력 보급을 가능하게 한다. 국내의 미전화 지역과 일반 가정에서 풍력 에너지 자원을 적극 활용 개발하기 위해서 보다 우수한 성능의 풍력발전기용 블레이드를 설계하고자, 공기역학적인 최적설계에 대해 연구함으로써 추후 보급형 풍력발전 시스템의 개발에 필요한 설계 기술을 확립하고자한다. 본 연구는 설계된 블레이드의 유동해석 및 성능예측을 위하여 경제적으로 많은 지원이 필요한 대규모 풍동실험이 아닌 상용 CFD를 사용하여 보다 효율적으로 우수한 성능을 가지는 풍력 터빈을 설계함에 있다. Reynolds Averaged Navier-Stokes 방정식에 기반을 둔 CFD의 경우 이론적으로 명확한 해석이 가능하고, 실제 터빈의 운전 환경과 동일한 다양한 물리적 변수를 입력 데이터로서 활용할 수 있는 장점이 있기 때문에 풍력 터빈의 설계 과정에서 반영된 미소한 블레이드 형상변화 및 운전 조건의 변화에 따른 유동장의 변화 및 풍력터빈 성능을 정확히 예측할 수 있는 장점을 가지고 있다.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.796-806
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• 2014

The key for the commercial deployment of IGCC power plants or chemical (methanol, dimethyl ether, etc.) production plants based on coal gasification is their economic advantage over plants producing electricity or chemicals from crude oil or natural gas. The better economy of coal gasification based plants can be obtained by co-production of electricity and chemicals. In this study, we carried out the economic feasibility analysis on the process of co-producing electricity and DME (dimethyl ether) using coal gasification. The plant's capacity was 250 MW electric and DME production of 300,000 ton per year. Assuming that the sales price of DME is 500,000 won/ton, the production cost of electricity is in the range of 33~58% of 150.69 won/kwh which is the average of SMP (system marginal price) in 2013, Korea. At present, the sales price of DME in China is approximately 900,000 won/ton. Therefore, there are more potential for lowering the price of co-produced electricity when comparing that from IGCC only. Since the co-production system can not only use the coal gasifier and the gas purification process as a common facility but also can control production rates of electricity and DME depending on the market demand, the production cost of electricity and DME can be significantly reduced compared to the process of producing electricity or DME separately.

• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.35-45
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• 2022

In this paper, we modeled the devices used easily in PV system circuits. In addition, for full operation of the photovoltaic system, a complete operation system for the DC-DC buck-boost converter and the MPPT control system was modeled and simulated to confirm good operation. we were constructed an actual system with the same conditions in the simulation and experimented. The purpose is to confirm the stable power supply through the load leveling by presenting the PCS considering ESS of photovoltaic power generation. we will do study to apply hybrid capacitors that have high energy density to the same size compared to the EDLC to DVR. As a result, we proposed a single-phase 3 kW grid-connected solar power converter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.394-399
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• 2008

There are many attempts to use a fuel cell system as a residential power generation system. The purpose of this study is to investigate the optimal design of a water tank for a hot water system when the fuel cell co-generation system is combined with a domestic hot water supply system. The demands of hot water supply per month per home are investigated in Busan for a year. It showed somewhat large differences between the actual demand and the designed demand of hot water, but the actual capacity of hourly averaged hot water demands is analyzed as $60{\ell}/h$ in this study based on the actual demand. The experiments are performed in the various inlet and outlet locations of nozzles, and the hot water consumption rates. The experimental results are showed that the optimal capacity of the water tank is $200{\ell}$ when the thermal efficiency, the storing capacity of hot water and the space for installation are considered.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.215-218
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• 2000

현재 원격 교육 시스템은 21세기를 맞이하여 고속 인터넷 통신망의 발전과 함께 사회전반에서 크게 이슈로 떠오르고 있다. 하지만, 현재는 특정업체나 단체에서 교육을 독점적으로 서비스하기 위해 웹 기반으로 서비스가 이루어질 뿐 일선 학교에서나 한국 산업인력관리공단과 같은 시험인증기관에서 특정 LAN (Local Area Network) 상에서 자체적으로 특정 교과 독립적으로 교육을 행할 수 있는 시스템이 없는 현실이다. 기존에 서비스되고있는 시스템은 순수 웹을 이용하거나 웹과 플러그인(Plug-in)을 함께 사용하여 컴퓨터에 지식이 없는 일선 학교의 교사나 학생들에게 순수한 양방향의 교육 서비스를 하기엔 역부족이고 한계가 있어 네트워크 기반 원격 교육 시스템을 제안하게 되었다. 본 연구에서 개발된 시스템의 주요 특징으로는 순수 인트라넷만을 이용하여 실시간 원격 교육서비스를 제공, 교육 공급자와 수요자에게 사용상에 특별한 지식을 요구하지 않는 사용자 인터페이스를 제공, 교육 정보갱신이 쉽고 빠르게 이루어지며, 특정교과 독립적으로 서비스가 가능하며, 서비스상에 특별한 인력을 필요로 하지 않으며, 수요자는 원하는 시간에 자신의 능력별로 서비스를 받을 수 있다. 그리고 가정 통신문, 성적 처리, 학생 신상 관리 등의 학생관리 기능이 있다. 필요하다면 사용자의 이용요금부고도 가능하다.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.126-133
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• 2009

The surfactants applied in household detergents and industrial cleansers should satisfy the requirement of not just the basic function such as emulsification, solubilisation, dispersion, detergency, wetting and foaming, but also the economical efficiency and the safety to human and environment. In the viewpoint of the sustainable development, the surfactants, moreover, have to reduce raw materials and energy consumption and waste disposal when they are being manufactured and also consumed for their purposes. New high-performance surfactants have been extensively studied and developed in order to respond the change in social and economical environment. Noticeable progresses have been achieved so far, which are the significant increase in solubility and surface activity through the minor modification of existing surfactant molecular structure and the synergistic increase in a surface activity shown in the mixed surfactant system of anionic and cationic surfactants. In this review, the important and meaningful progresses achieved recently in technological advance and practical application will be summarized and discussed.

• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.519-547
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• 2005

The aim of this study is to analysis how economic welfare lost happens within the present korea seasonal and time period electricity pricing system and find out reasonable electricity price system acceptable during the transitional period of korea electricity industry restructuring To analyze economic welfare lost in the electricity industry, in advance seasonal and time periodic 9 demand curves(summer, spring ＆fall, winter/peak-load time, middle-load time, low-load time) and one market supply curve are made and then using these demand and supply curve, seasonal and time periodic market equilibrium prices is calculated. Finally, comparing these market equilibrium prices with present regulated classified seasonal and time periodic prices, the whole economic welfare lost in the electricity industry is calculated. The result of this study shows that in 2002, the total economic welfare lost in electricity industry is 137,770 million Won and under present price system, the worst welfare lost is happening seasonally in spring ＆ fall, time periodically in the middle-load time. Specifically analyzing the characteristics of welfare lost, especially on the industry customers and service customers which are applied in seasonal and time periodic pricing, for the industry customers, the welfare lost calculated in this class occupies 51% of the total welfare lost in the whole electricity industry and the worst welfare lost is happening seasonally in spring ＆ fall, time periodically in the middle-load time. For service customers, the welfare lost calculated in this class occupies 13% of the total welfare lost in the whole electricity industry and the worst welfare lost is happening seasonally in summer, time periodically in the peak time Finally, this study was made based on the year of 2002 and KEPCO has practiced two times of rate change until now. The result of rate change was positively analyzed in the direction of economic welfare improvement(welfare improvement achieved by 16.3% compared to 2002 result).