• Title/Summary/Keyword: commercial power

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Experimental Study of Embedding Motion and Holding Power of Drag Embedment Type Anchor (DEA) on Sand Seafloor (해성 모래지반에서 Drag Embedment Type Anchor Model의 파지 운동 및 파지력에 대한 실험적 연구)

  • Lee, Jae-Hoon;Seo, Byoung-Cheon;Shin, Hyunk-Young
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.2
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    • pp.183-187
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    • 2011
  • As larger the commercial vessel is, and rougher the marine environment becomes nowadays, drag embedment type anchor (DEA) of more stable performance and higher holding power is requested to be applied on the vessel. But, the performance of DEA has not become well known to academy and industries so far, that the basic study of DEA performance and holding force for the development of new DEA of higher performance is insufficient that required. In this paper, three types of same holding category DEA model (HALL, AC-14, POOL-N, scale 1/10), which are generally applied on the commercial vessel nowadays, were tested by being horizontally dragged on the test tank, on which sand was being floored with sufficient depth, and measured the holding force of each anchor simultaneously using load cell and D/A converter. With the test results, the embedding motion was analyzed to have three different stages and the holding force of each anchor was analyzed with respect to the anchor geometry, such as shape and weight of each type of anchors, and final embedding depth.

The Predictive Power of Multi-Factor Asset Pricing Models: Evidence from Pakistani Banks

  • SALIM, Muhammad;HASHMI, Muhammad Arsalan;ABDULLAH, A.
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.11
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    • pp.1-10
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    • 2021
  • This paper compares the performance of Fama-French three-factor and five-factor models using a dataset of 20 Pakistani commercial banks for the period 2011 to 2020. We focus on an emerging economy as the findings from earlier studies on developed countries cannot be generalized in emerging markets. For empirical analysis, twelve portfolios were developed based on size, market capitalization, investment strategy, and growth. Subsequently, we constructed five Fama-French factors namely, RM, SMB, HML, RMW, and CMA. The OLS regression technique with robust standard errors was applied to compare the predictive power of both the Fama-French models. Further, we also compared the mean-variance efficiency of the Fama-French models through the GRS test. Our empirical analysis provides three unique and interesting findings. First, both asset pricing models have similar predictive power to explain the expected portfolio returns in most cases. Second, our results from the GRS test suggest that there is no noticeable difference in the mean-variance efficiency of one asset pricing model over the other. Third, we find that all factors of both Fama-French models are statistically significant and are important for explaining the volatility of expected commercial bank returns in the context of Pakistan.

Design of Power and Load Reduction Controller for a Medium-Capacity Wind Turbine (중형 풍력터빈의 출력 및 타워 하중저감 제어기 설계)

  • Kim, Kwansu;Paek, Insu;Kim, Cheol-Jin;Kim, Hyun-Gyu;Kim, Hyoung-Gil
    • Journal of the Korean Solar Energy Society
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    • v.36 no.6
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    • pp.1-12
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    • 2016
  • A control algorithm for a 100 kW wind turbine is designed in this study. The wind turbine is operating as a variable speed variable pitch (VSVP) status. Also, this wind turbine is a permanent magnet synchronous generator (PMSG) Type. For the medium capacity wind turbine considered in this study, it was found that the optimum tip speed ratios to achieve the maximum power coefficients varied with wind speeds. Therefore a commercial blade element momentum theory and multi-body dynamics based program was implemented to consider the variation of aerodynamic coefficients with respect to Reynolds numbers and to find out the power and thrust coefficients with respect tip speed ratio and blade pitch angles. In the end a basic power controller was designed for below rated, transition and above rated regions, and a load reduction algorithm was designed to reduce tower vibration by the nacelle motion. As a result, damage equivalent Load (DEL) of tower fore-aft has been reduced by 32%. From dynamic simulations in the commercial program, the controller was found to work properly as designed. Experimental validation of the control algorithm will be done in the future.

Modeling of Solid Particle-Slag Interactions in Entrained Gasification Reactor (분류층 가스화기에서의 고체 입자-슬래그 간 상호 작용에 대한 모델링)

  • Chi, Jun-Hwa;Kim, Ki-Tae;Kim, Sung-Chul;Chung, Jae-Hwa;Ju, Ji-Sun;Kim, Ui-Sik
    • Journal of Hydrogen and New Energy
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    • v.22 no.5
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    • pp.686-698
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    • 2011
  • Mathematical models for char-slag interaction and near-wall particle segregation developed by Montagnaro et. al. were applied to predict various aspects of coal gasification in an up-flow entrained gasifier of commercial scale. For this purpose, some computer simulations were performed using gPROMS as the numerical solver. Typical design parameters and operating conditions of the commercial gasifiers were used as input values for the simulation. Development of a densely dispersed phase of solid carbon was found to have a critical effect on both carbon conversion and ash flow behavior. In general, such a slow-moving phase was turned out to enhance carbon conversion by lengthening the residence time of char or soot particles. Furthermore, it was also found that guiding the transfer of char or soot into the closer part of the wall to coal burner is favorable in terms of gasification efficiency and vitrified ash collection. Finally, to a certain degree densely dispersed phase of carbon showed an yield-enhancing effect of syngas.

Calculation of preliminary site-specific DCGLs for nuclear power plant decommissioning using hybrid scenarios

  • Seo, Hyung-Woo;Sohn, Wook
    • Nuclear Engineering and Technology
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    • v.51 no.4
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    • pp.1098-1108
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    • 2019
  • Korea's first commercial nuclear power plant at Kori site was permanently shut down in 2017 and is currently in transition stage. Preparatory activities for decommissioning such as historical site assessment, characterization, and dismantling design are being actively carried out for successful D&D (Dismantling and Decontamination) at Kori site. The ultimate goal of decommissioning will be to ensure the safety of workers and residents that may arise during the decommissioning of nuclear facilities and, thereby finally returning the site to its original status in accordance with the release criteria. Upon completion of decommissioning, the resident's safety at a site released will be assessed from the evaluation of dose caused by radionuclides expected to be present or detected at the site. Although the U.S. commercial nuclear power plants with decommissioning experience use different site release criteria, most of them are 0.25 mSv/y. In Korea, both the unrestricted and restricted release criteria have been set to 0.1 mSv/y by the Nuclear Safety and Security Commission. However, since the dose is difficult to measure, measurable concentration guideline levels for residual radionuclides that result in dose equivalent to the site release criteria should be derived. For this derivation, site reuse scenario, selection of potential radionuclides, and systematic methodology should be developed in planning stage of Kori site decommissioning. In this paper, for calculation of a preliminary site-specific Derived Concentration Guideline Levels (DCGLs) for the Nuclear Power Plant site, a novel approach has been developed which can fully reflect practical reuse plans of the Kori site by taking into account multiple site reuse scenarios sequentially, thereby striking a remarkable distinction with conventional approaches which considers only a single site scenario.

The Introduction of #2 HVDC SYSTEM (육지-제주간 2차 HVDC SYSTEM 개요)

  • Jang, Suk-Han;Yoo, Sung-Hwan;Shin, Myoung-Sik;Lee, Gyu-Yong
    • Proceedings of the KIEE Conference
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    • 2008.11a
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    • pp.107-109
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    • 2008
  • Cheju-Haenam HVDC transmission system start it's commercial operation since 1998. JEJU island is supplied with it's about 45% of total electric power from main land with HVDC link. In JEJU island, the demand of electric power is growing every year. With a current power supply, electric power reserve rate will be below the recommended one. For a stable power supply to JEJU island, KEPCO start a construction of #2 HVDC transmission system. This report is for introduction and understanding of #2 HVDC system which will be installed between JEJU island and main land. This report includes a specification of converter station and DC cable. KEPCO expect that this system will solve the power supply problem and maximum wind power plant capacity problem as well.

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The Conceptual Design and Estimate of Fault Current Limiter Using High-Tc superconducting Tape (고온 초전도선재를 이용한 사고 전류 제한 장치의 개념 설계 및 효용 평가)

  • Lee, Seung-Je;Lee, Chan-Joo;Jang, Mi-Hye;Kim, Tae-Jung;Hyun, Ok-Bae;Ko, Tae-Kuk
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.134-137
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    • 1999
  • It is certain that the power quality will be very important at 21 century. Especially instant power shortage or power fault will occur serious problems. Accordingly stable power supplication is very technical problem. There are many way to make stable supplication as auxiliary generator, but this is long time delay complement. To solve this problem the superconducting magnetic energy storage is introduced. High Tc superconductor is more commercial.

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Ku-Band Power Amplifier MMIC Chipset with On-Chip Active Gate Bias Circuit

  • Noh, Youn-Sub;Chang, Dong-Pil;Yom, In-Bok
    • ETRI Journal
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    • v.31 no.3
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    • pp.247-253
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    • 2009
  • We propose a Ku-band driver and high-power amplifier monolithic microwave integrated circuits (MMICs) employing a compensating gate bias circuit using a commercial 0.5 ${\mu}m$ GaAs pHEMT technology. The integrated gate bias circuit provides compensation for the threshold voltage and temperature variations as well as independence of the supply voltage variations. A fabricated two-stage Ku-band driver amplifier MMIC exhibits a typical output power of 30.5 dBm and power-added efficiency (PAE) of 37% over a 13.5 GHz to 15.0 GHz frequency band, while a fabricated three-stage Ku-band high-power amplifier MMIC exhibits a maximum saturated output power of 39.25 dBm (8.4 W) and PAE of 22.7% at 14.5 GHz.

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The Forward Type High Frequency Pulse Power Supply (Forward형 고주파 펄스 전원장치)

  • 김경식;원재선;송현직;김동희;이광식
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 1999.11a
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    • pp.184-188
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    • 1999
  • The power semiconductor switching devices(PSSD) continuously developed, Power Electronic Technology using PSSD is gradually extended. The high frequency inverter to generate the large power high frequency subject to power electronic technology pursuit various applications. Also, in emboss with environmental destruction problem cause the atmosphere and the water pollution to growth of the commercial society, the research in favor of cleaning environmental a pollutant actively proceed. Therefore, This paper describe study on the high frequency pulse power supply. The theoretical results are in good agreement with the experimental ones. The proposed pulse power supply is considerated to be useful for discharge lamp.

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Implementation of Control System for Remote Load using Power line Communication (전력선 통신을 이용한 원격 부하제어 시스템의 구축)

  • Kim Ho;Lee Won-Sun;Jeon Hee-Jong;Park Jong-chan
    • Proceedings of the KIPE Conference
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    • 2002.07a
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    • pp.685-688
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    • 2002
  • This paper deals with new scheme of remote load control management system with communication from RCU to controller using power line Power line communication is useful for economical data link but various problems and limitations are caused in using power lines for communications channel. A power line is not so good in the commercial electrical power, and its load noise and high frequency noise are so much. To decrease these noise, we used the FSK(Frequency Shift Keying) modulation method. The experimental results show that the proposed system in this paper is compatible with the conventional system with low cost and the feasibility is very high for new or remodeling plant.

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