• Title/Summary/Keyword: network-based distributed control system

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Theory and practice of the interlibrary loan service (상호대차(相互貸償) 제도의 이론(理論)과 응용)

  • Chun Myung Sook
    • Journal of the Korean Society for Library and Information Science
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    • v.13
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    • pp.39-71
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    • 1986
  • Interlibrary loan has been a very common library service in the developed countries but it is yet to be actualized formerly in Korea. As Korea is moving toward an information society where all the individual user's request in the library should be met, we need to understand, in detail, the theory and practice of interlibrary loan service. As various information technology has been applied to the libraries, the libraries became the open system. Thus, the libraries become more cooperative, form networks, and make interlibrary loan service available. This study is based on the following three hypothesis formulated from the systems theory. 1. If libraries cooperate each other and form some kind of networks by mail, computers or telecommunications, they become the open system. 2. If a library develops as the open system, interlibrary loan becomes available in the library. 3. If the interlibrary loan system works, the role of the librarians will be changed. The research was carried out by analyzing the various studies about interlibrary loan service and by examining the interlibrary loan systerns presently working in the U.S.. The conclusions are reached deductively from the data. Some of the terminology used are defined as follows: System: a network of interrelated procedures that are joined together to perform an activity or to accomplish a specific objective. It is, in effect, all the ingredient which make up the whole. Cooperation: Working together to benefit participant libraries. Network: a much more structured type of cooperation in which definite regions or areas are connected by electronic or other means to promote interlibrary loaning of materials, in-service traing & other sharing of resources. Interlibrary loan: the lending of books between libraries. The model of cooperation or networks was used to be (1) a star type, (2) a hieranchical type, (3) a distributed type or (4) the combination of aforementioned three. However, the development of the telecommunications and computers enables all kinds of libraires cooperate together. Interlibrary loan service starts with the needs of user's information. The information have to be logically accessed through bibliographies, computers, electronic mails and satellite communications. And the logical access requires the information technology and the libraries become cooperative. The physical access to the information follows next but only traditional method of mail and some commercial service are currently available for this purpose. Therefore, researches are needed to develop this physical access. If the libraries form networks, the microaspect of library changes accordingly as the macroaspect changes. If the libraries . cooperate to become one large world library, the librarians plan, organize, control library operations and report the results. And the librarians work inside and outside of the library to cooperate with other libraries. Only the cooperation of the libraries will enhance interlibrary loan and the Korean librarians have to be prepared to accept the new role of librarianship for the interlibrary loan service.

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Mobile Edge Computing based Charging Infrastructure considering Electric Vehicle Charging Efficiency (전기자동차 충전 효율성을 고려한 모바일 에지 컴퓨팅 기반 충전 인프라 구조)

  • Lee, Juyong;Lee, Jihoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.669-674
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    • 2017
  • Due to the depletion of fossil fuels and the increase in environmental pollution, electric vehicles are attracting attention as next-generation transportation and are becoming popular all over the world. As the interest in electric vehicles and the penetration rate increase, studies on the charging infrastructure with vehicle-to-grid (V2G) technology and information technology are actively under way. In particular, communication with the grid network is the most important factor for stable charging and load management of electric vehicles. However, with the existing centralized infrastructure, there are problems when control-message requests increase and the charging infrastructure cannot efficiently operate due to slow response speed. In this paper, we propose a new charging infrastructure using mobile edge computing (MEC) that mitigates congestion and provides low latency by applying distributed cloud computing technology to wireless base stations. Through a performance evaluation, we confirm that the proposed charging infrastructure (with low latency) can cope with peak conditions more efficiently than the existing charging infrastructure.

A Study for Promotion Strategies of the Smart Grid in Convergence technology (융합기술을 활용한 스마트그리드 촉진전략에 관한 연구)

  • Mun, Jeong-Min;Leem, Wook-Bin;Cho, Sae-Hong
    • Journal of Digital Contents Society
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    • v.15 no.4
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    • pp.513-520
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    • 2014
  • The Smart Grid is next-generation power system materialized Convergence and Integration of power technologies and Information Technologies. And this system is the next generation power system optimizing energy efficiency via real-time information exchanges grafting the information technologies upon present power networks which are web-net. The introduction of smart grid can be embodied for latitude, distributed and cooperated network by inter-active exchange of energy information between electrical power provider and consumer previous uni-directional electrical power supplement. Therefore in this paper, we proposed Convergence technologies - Smart power grid, Smart Place, Smart Renewable and Smart Electricity Service - to make smart-grid succeed via analyzing the datum. And we scoped on Convergence and Integration technologies, which could be used for smart-power-grid that is most important factor to replace previous power industries. And we brought out the expecting industrialize timing and interesting aspects and analyzed the result with survey of professional worker from institute, research center, power plant and business of power industries. And proposed the essential policies for the government and power-control-business companies based on the datum and survey output.

Reactive Power Variation Method for Anti-islanding Using Digital Phase-Locked-Loop (DPLL을 이용한 능동적 단독운전방지를 위한 무효전력변동법)

  • Lee, Ki-Ok;Yu, Byung-Gu;Yu, Gwon-Jong;Choi, Ju-Yeop;Choy, Ick
    • Journal of the Korean Solar Energy Society
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    • v.28 no.2
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    • pp.64-69
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    • 2008
  • As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, these have raised potential problems of network protection on electrical power system. One of the numerous problems is an Islanding phenomenon. There has been an argument that it may be a non-issue in practice because the probability of islanding is extremely low. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an islanding can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficiently to cause a trip, plus the time required to execute a trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. Third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an islanding. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. Therefore the verification of anti-islanding performance is strongly needed. In this paper, improved RPV method is proposed through considering power quality and anti-islanding capacity of grid-connected single-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation results are verified.

Development of a technology valuation method for buyers in technology transfer (기술이전을 위한 기술수요자 중심의 가치평가 방법론 개발)

  • Yun, DooSeob;Park, Inchae;Yoon, Byungun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.11
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    • pp.155-167
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    • 2016
  • Technology valuation is necessary for determining the feasibility of technology commercialization. However, existing methods focus only on technology evaluation, with limitation in sufficiently reflecting buyer viewpoint. In addition, it causes a gap between estimated value and market value. Therefore, this research suggests a new technology valuation method which focuses on the perspectives of buyers. Technology factors, buyer factors and market factors are first determined and their relationships are analyzed. Second, based on the relationships, profit projections are calculated using the discount cash flow method. Finally, profit projections for each year are discounted. The proposed method was applied using the ubiquitous home network system and audio service and illumination control method and results compared with the value of a technology valuation guide distributed by the Ministry of Trade, Industry and Energy. The technology valuation approach used in this research is quantitative and systematic and can be used as a decision making support tool in technology transfer, reflecting various perspectives of stakeholders.