• 제목/요약/키워드: power trade

검색결과 577건 처리시간 0.027초

An Improved Incremental Conductance MPPT Method for the Photovoltaic Generation

  • Wellawatta, Thusitha;Choi, Sung-Jin
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2016년도 전력전자학술대회 논문집
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    • pp.185-186
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    • 2016
  • Maximum power point tracking (MPPT) techniques play a big role in improving the efficiency of photovoltaic (PV) system. Among various schemes, the incremental conductance (INC) method is mostly discussed in literature because of its fast response to the rapid irradiation changes and high tracking accuracy. However, the existing INC algorithm has trade-offs between fast dynamic response and steady state stability. This study proposes a novel INC method to meet high efficiency and fast tracking performance at the same time.

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송전선로 시공기술의 현황과 전망 (Present Status and Prospect of Transmission Line Constructions)

  • 이형권;장희천;김효진
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1999년도 하계학술대회 논문집 C
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    • pp.1388-1390
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    • 1999
  • Environments of electric power industries are fastly changing due to the WTO, opening of the capital market and free trade. Accordingly, it is very important to invest in technical developments for securing international competitive power. But our construction techniques in T/L are insufficient in comparing with the advanced countries. This paper suggests the status and prospect of construction techniques of domestic and foreign countries in T/L, including developing prospects of T/L constriction.

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원자력 발전소의 최적 운행중지 시기 결정 방법 (Deciding the Optimal Shutdown time of a Nuclear Power Plant)

  • 양희중
    • 산업공학
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    • 제13권2호
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    • pp.211-216
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    • 2000
  • A methodology that determines the optimal shutdown time of a nuclear power plant is suggested. The shutdown time is decided considering the trade off between the cost of accident and the loss of profit due to the early shutdown. We adopt the bayesian approach in manipulating the model parameter that predicts the accidents. We build decision tree models and apply dynamic programming approach to decide whether to shutdown immediately or operate one more period. The branch parameters in decision trees are updated by bayesian approach. We apply real data to this model and provide the cost of accidents that guarantees the immediate shutdown.

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Certain Clean Decompositions for Matrices over Local Rings

  • Yosum Kurtulmaz;Handan Kose;Huanyin Chen
    • Kyungpook Mathematical Journal
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    • 제63권4호
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    • pp.561-569
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    • 2023
  • An element a ∈ R is strongly rad-clean provided that there exists an idempotent e ∈ R such that a - e ∈ U(R), ae = ea and eae ∈ J(eRe). In this article, we completely determine when a 2 × 2 matrix over a commutative local ring is strongly rad clean. An application to matrices over power-series is also given.

전력시스템에서의 웨이브릿 변환 적용 사례 (An overview on applications of wavelet transform in power systems)

  • 김창일;유인근
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 A
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    • pp.369-372
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    • 2000
  • An overview on applications of wavelet transform in power systems presented in this paper. Wavelet transform is capable of making trade-offs between time and frequency resolutions, which is a property that makes it appropriate for the analysis of non stationary signal. In recent years, wavelet transform is widely accepted as a technology offering an alternative way due to its flexibility in representation of non-stationary signal even in power systems. This paper presents various applications of wavelet transform in power systems. Wavelet transform has been used by the authors in the field of power system protection for the classification of transient signals, and forecasting of short term loads and system marginal price and so on. Various research works carried out by many researchers in power systems are summarized.

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어레이 접지전압 조정에 의한 저전력, 고성능 내장형 SRAM 회로 기술 (Low power-high performance embedded SRAM circuit techniques with enhanced array ground potential)

  • 정경아;손일헌
    • 전자공학회논문지C
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    • 제35C권2호
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    • pp.36-47
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    • 1998
  • Low power circuit techniques have been developed to realize the highest possible performance of embedded SRAM at 1V power supply with$0.5\mu\textrm{m}$ single threshold CMOS technology in which the unbalance between NMOS and PMOS threshold voltages is utilized to optimize the low power CMOS IC design. To achieve the best trade-off between the transistor drivability and the subthreshold current increase, the ground potential of memory array is raised to suppressthe subthreshold current. The problems of lower cellstability and bit-line dealy increase due to the enhanced array ground potential are evaluated to be controlled within the allowable range by careful circuit design. 160MHz, 128kb embedded SRAM with 3.4ns access time is demonstrated with the power consumption of 14.8mW in active $21.4{mu}W$ in standby mode at 1V power supply.

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확률모형을 이용한 무선센서망 수명 최대화에 관한 분석 (A Stochastic Model for Maximizing the Lifetime of Wireless Sensor Networks)

  • 이두호;양원석
    • 한국경영과학회지
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    • 제37권3호
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    • pp.69-78
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    • 2012
  • Reduction of power consumption has been a major issue and an interesting challenge to maximize the lifetime of wireless sensor networks. We investigate the practical meaning of N-policy in queues as a power saving technique in a WSN. We consider the N-policy of a finite M/M/1 queue. We formulate the optimization problem of power consumption considering the packet loss probability. We analyze the trade-off between power consumption and the packet loss probability and demonstrate the operational characteristics of N-policy as a power saving technique in a WSN with various numerical examples.

Considerations on the use of a Boost PFC Regulator Used in Household Air-conditioning Systems (over 3kW)

  • Jang Ki-Young;Suh Bum-Seok;Kim Tae-Hoon
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2002년도 전력전자학술대회 논문집
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    • pp.589-592
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    • 2002
  • The CCM (Continuous Conduction Mode) boost topology is generally used in the PFC (Power Factor Correction) regulator of household air-conditioning systems. There are three kinds of power devices-bridge rectifier diodes, FRDs (Fast Recovery Diodes), and IGBTs (or MOSFETs) - used In a boost PFC regulator. Selecting the appropriate device is very cumbersome work, specially, in the case of FRDs and IGBTs, because there are several considerations as described below: 1) High frequency leakage current regulation (conducted and radiated EMI regulation) 2) Power losses and thermal design 3) Device cost. It should be noted that there are trade-offs between the power loss characteristic of 2) and the other characteristics of 1) and 3). This paper presents a detailed evaluation by using several types of power devices, which can be unintentionally used, to show that optimal selection can be achieved. Based on the given thermal resistances, thermal analysis and design procedures are also described from a practical viewpoint.

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국제대금결제에서의 신용위험 대처방안에 관한 연구 - 국제팩토링.포페이팅을 중심으로 - (A Study on the Exporter's Measures against Credit Risks in International Payment System - focus on international factoring.forfaiting -)

  • 오원석;박세훈
    • 무역상무연구
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    • 제39권
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    • pp.143-175
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    • 2008
  • The documentary letter of credit is the most preferred and frequently used method in International Payment System in Korea, as it has less possibility of occurring credit risks in export than any other payment system. That's because the exporter can get payment from the issuing bank(confirming bank) by delivering the goods and presenting documents following the required procedure under the letter of credit, as the payment is affirmed by the issuing bank(including the confirming bank in case of the confirmed letter of credit) regardless of the buyer's payment. However, the pattern of payment methods used in international trade of Korea is changing dramatically like the importance of the credit is decreasing continuously among the payment methods while the remittance is increasing. The increase of remittance has a positive aspect that International Payment System are changing into those of advanced countries, but the decrease of the credit also has a negative aspect that the exporter might have a greater credit risks. Therefore, we need a systematic device to deal with this. Exporters in Korea usually have used the export credit insurance to deal with the credit risks However, the export credit insurance also have a limitation as the policy finance due to the limitation based on the credit status of the business and the limitation of acceptance from the lack of financial resources of the government, etc. Korea, which is the 11th export power in the world, has a basic limitation to deal with the credit risks by depending on the export credit insurance only. So, in this thesis, I have studied on the international factoring, forfaiting, which are advanced export finances and widely used in advanced countries, as substitutes to deal with the credit risks. the international factoring is an trade financing in which a factor offers full services such as credit cover, offering prepayment, collection, account receivables, management, etc, instead of the exporter on the account receivables occurred by the exporter's delivering goods to the importer. This international factoring has a high possibility of using as a means to deal with the credit risks, because it offers prepayment without recourse. the forfaiting is another export financing in which a forfaiter purchases the draft, the promissory note and other negotiable instruments issued from the international trade, with fixed interest rate without recourse from the exporter or previous holder. By using this method, they can avoid foreign exchange risks, contingency risks as well as credit risks, as the conveyances like the promissory note, etc are issued with the note warranty so-called 'per aval' in business practice. These trade financing are good substitutes to deal with the credit risks in export, but they are not widely used in Korea. Though it can be explained with various reasons, the common reasons are the lack of understanding on the use of advanced export finance, the lack of experts to manage the advanced trade finance, the conservative way of thinking of domestic organizations related to trade financing, the lack of organizations supporting the trade financing, etc.

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회원사 탐방-(주)포토닉스트레이드그룹

  • 한국광산업진흥회
    • 광산업정보
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    • 통권34호
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    • pp.20-23
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    • 2006
  • 해외 P.T.G로 잘 알려져 있는 Photonics Trade Group은 광산업군민을 전문으로 구매 및 판매를 지원하는 다국적 광무역회사이다. 현재 48개국 75개사 에이전트 및 13개국 21개 광관련 단체와의 협업사업을 추진할 정도의 막강한 Brand Power를 자랑하고 있다. 국내광산업체를 위해 C 회사에 대해 알아보고자 한다.

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