• 한국유체기계학회 논문집
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• 제1권1호
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• pp.7-16
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• 1998

An interactive mode of grid generation system has been developed for a Navier-Stokes design procedure of axial flow compressors. The present grid generator adopts the multiblock H-grid structure, which simplifies the creation of computational grids about complex turbomachinery geometries and facilitate the manipulation of multiple grid blocks for multirow flow fields. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The system consists of four separated modules, which are linked together with a common graphical user interface. The system input is made of the results of the preliminary design. The final grids generated from each module of the system are used as the preprocessor for the performance prediction of the two-or three-dimensional flow simulation inside the blade passage. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure of the turbomachinery cascades using the Navier-Stokes technique.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.735-737
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• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• ETRI Journal
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• 제36권1호
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• pp.80-88
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• 2014

Recently, the idea of the smart grid has been gaining significant attention and has become a hot research topic. The purpose of this paper is to present a novel smart grid management scheme that uses game theory principles. In our proposed scheme, power appliances in the smart grid adaptively form groups according to the non-cooperative hedonic game model. By exploiting multi-appliance diversity, appliances in each group are dynamically scheduled in a cooperative manner. For efficient smart grid management, the proposed coopetition game approach is dynamic and flexible to adaptively respond to current system conditions. The main feature is to maximize the overall system performance while satisfying the requirements of individual appliances. Simulation results indicate that our proposed scheme achieves higher energy efficiency and better system performance than other existing schemes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.280-282
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• 2005

Micro-source units having power ratings in thousands of watts can provide even higher reliability and fuel efficiency than the conventional large scale units. These units are also clustered with loads creating micro-grid services to customer sites such as office buildings, industrial parks and homes. Micro-sources adopt voltage source inverter to ensure the power quality of sensitive loads. This paper deals with the connection of micro-sources into the system grid. Modeling and simulation of the grid connected micro-sources at the power frequency range are investigated. Simulation results show that the micro-grid system with two micro-sources has good dynamic characteristics.

• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.233-244
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• 2016

Smart grid is called it as a system of systems. There are diverse types of systems in smart grid environment. Therefore, one of key factors to achieve smart grid successfully is interoperability among diverse systems. To secure interoperability, smart grid operating system should be developed complied with standards in terms of the data representation and communication. Common Information Model (CIM) and OLE Process for Control - Unified Architecture (OPC-UA) are the representative international standards in smart grid domain. Each standard defines data representation and communication by providing common information model and the unified architecture. In this paper, we explain a smart grid platform that we have developed to comply with CIM and OPC-UA standards for secure interoperability among numerous legacy systems.

• 전기학회논문지
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• 제60권7호
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• pp.1347-1353
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• 2011

While most of the existing protection schemes have been designed with local information around individual components, these local schemes are not considered capable of protecting the modern electric power gird with growing complexity. Recent blackouts in North America and Europe have renewed the emphasis on coordinated protection and control actions to avoid systemwide blackouts, utilizing all of the available grid information. Thus, this paper proposes a new methodology, Agent-based Colored Petri Net (ACPN) modeling for systematically representing, modeling and analyzing information flows and interactions among the entities of the electric power grid. The paper demonstrates its efficacy and accuracy by investigating an ACPN model of a wide area protection system for a typical power grid. The proposed modeling and analysis schemes may further provide a framework to help assure reliability and interoperability of diverse smart grid components.

• 전력전자학회논문지
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• 제20권1호
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• pp.91-103
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• 2015

This paper investigates control algorithms for a doubly fed induction generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage wind power system under unbalanced grid conditions. Negative sequence control algorithms to compensate for unbalanced conditions have been investigated with respect to four performance factors: fault ride-through capability, instantaneous active power pulsation, harmonic distortions, and torque pulsation. The control algorithm having zero amplitude of torque ripple indicates the most cost-effective performance in terms of torque pulsation. The least active power pulsation is produced by a control algorithm that nullifies the oscillating component of the instantaneous stator active and reactive power. A combination of these two control algorithms depending on operating requirements and depth of grid unbalance presents the most optimized performance factors under generalized unbalanced operating conditions, leading to a high-performance DFIG wind turbine system with unbalanced grid adaptive features.

• 한국컴퓨터정보학회논문지
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• 제12권3호
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• pp.19-26
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• 2007

최근 포털 시스템이 그리드환경의 사용자 인터페이스로 많이 이용되고 있다. 전통적인 포털 시스템은 아이디와 패스워드를 사용자 인증방식으로 사용하는 반면 그리드 시스템은 공개키와 개인키로 이루어진 대칭키를 기반으로 사용자 인증을 수행한다. 이와 관련하여 포털 시스템의 사용자 계정과 그리드 시스템의 대칭키를 중심으로 포털과 그리드시스템의 통합에 대한 많은 연구가 진행중이다. 특히 GAMA와 PURSE 처럼 아이디, 패스워드 방식에 익숙한 사용자의 편의성에 초점을 둔 연구가 활발하다. 그러나 그리드 환경은 네트워크를 통한 연결을 전제로 하기 때문에 공유되는 데이터와 자원의 보호가 중요하다. 따라서 본 논문에서는 UI 계층에서 대칭키를 사용하여 포털 시스템과 그리드 시스템의 인증 방식을 단일화함으로써 그리드의 사용자 환경에서도 보안 수준을 향상시키는 방안을 제안하고자 한다.

• 전기학회논문지P
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• 제64권1호
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• pp.18-22
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• 2015

When using a secondary battery in energy storage units, if the grid is in light duty the active power is stored so it can be used when the grid is in heavy duty. This makes possible for the load equalize and make the grid optimized. Recently the government is trying to propagate this technology. Depending on its capacity this kind of electric energy storage unit is used in adjusting the frequency, break up the energy peak in summer and winter, stabilize the energy output of renewable energy which can change unstably because of the environment. Which makes it possible to stabilize the grid. It is anticipated that market of 120 trillion won will be developed worldwide in 2030. Currently in Korea a steady supply is in progress. However because of stray electromagnetic waves some other electronics are malfunctioning. This paper covers the research in the method to detect the emission noise in small electric energy storage units using lithium secondary batteries and battery management system, Power conditioning systems with CIPSR standards. And the research of a more efficient method to measure such stray electromagnetic waves.

• 통합자연과학논문집
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• 제15권2호
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• pp.89-97
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• 2022

This paper presents the comprehensive feasibility study of solar mini-grid project located in Bajhang District, Sudur Paschim Province, Nepal. The study has been conducted with the aim of developing a suitable size solar mini-grid system to meet electricity demand of proposed settlements of the village people. The study forecasts that the estimated average daily peak power consumption of load is about 20kW and average daily energy demand of load is about 100-150kWh/day in the base year 2022. The shared ratio of productive end uses is about 25% of the total power consumption and about 27% of the total energy demand, which will be used for small business/income generation activities and required 45kWp size solar power generation mini-grid system. The estimated project cost for the proposed 45kW solar mini-grid system technology, including 3 years of operation & maintenance, as well as power distribution network up to end user's premises is about 0.24 million USD. It is concluded that 45kWp photovoltaic mini-grid is feasible for the location.