• Title, Summary, Keyword: Expected efficiency

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Asymptotic Relative Efficiency of t-test Following Transformations

  • Yeo, In-Kwon
    • Journal of the Korean Statistical Society
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    • v.26 no.4
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    • pp.467-476
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    • 1997
  • The two-sample t-test is not expected to be optimal when the two samples are not drawn from normal populations. According to Box and Cox (1964), the transformation is estimated to enhance the normality of the tranformed data. We investigate the asymptotic relative efficiency of the ordinary t-test versus t-test applied transformation introduced by Yeo and Johnson (1997) under Pitman local alternatives. The theoretical and simulation studies show that two-sample t-test using transformed date gives higher power than ordinary t-test for location-shift models.

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Optimal Redundant Units and Load in Parallel Systems (병렬 시스템에서의 최적 중복부품수와 최적 부하수준)

  • 윤원영;김귀래
    • Journal of the Korean Operations Research and Management Science Society
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    • v.23 no.1
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    • pp.97-107
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    • 1998
  • This paper is concerned with a parallel system that sustains a time-independent load and consists of n components with exponential lifetimes. It is assumed that the total load is shared by the working components and the failures of components increase higher failure rates in the surviving components according to the relationship between the load and the fialure rates. The power rule model among several load-failure rate relationships is considered. We consider the system efficiency meausre as the expected profit earned by the system per unit time. The high load causes high gain but it also occurs frequent system failures. The expected profit per unit time is used as criterion to evaluate the system efficiency. The goal of system engineer is to determine the optimal load and redundant units maximizing the expected profit per unit time. First, the system reliability function is obtained and the optimization problem of the load-sharing parallel system is considered. Given the redundant units, the existence of the optimal load can be proved analytically and given the load, the optimal redundant units can be solved also analytically. The optimal load and redundant units are obtained simultaneously by numerical computation. Some numerical examples are studied.

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EFFICIENCY MEASUREMENT AND ENERGY ANALYSIS FOR A HEV BENCH TESTER AND DEVELOPMENT OF PERFORMANCE SIMULATOR

  • OH K.;KIM D.;KIM T.;KIM C.;KIM H.
    • International Journal of Automotive Technology
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    • v.6 no.5
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    • pp.537-544
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    • 2005
  • This paper presents the efficiency measurement and energy analysis for a parallel HEY. Using the HEV test rig, the efficiency of each powertrain component is measured for a given driving cycle including the regenerative braking system. Accompanied by the efficiency measurements, a detailed energy analysis is performed. Based on the efficiency measurement and energy analysis, a HEV performance simulator is developed. Using the simulator, the HEV performance is evaluated for a mild hybrid system. It is expected that the HEV simulator developed can be used to obtain further optimization potentials.

High Efficiency Tracking Drive in DC Motor by Field Winding Switching Method (계자권선 절환에 의한 직류전동기의 고효율 추종 운전)

  • Yoon, Ki-Jeong;Kim, Kwang-Heon
    • Proceedings of the KIEE Conference
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    • pp.493-496
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    • 1997
  • This paper constructed the experimental system which is able to drive in series or separately excited by switching of the field winding, using a DC motor and obtained the characteristics of efficiency with speed and torque of each motor's type through the experiment. From this result controlled drive which is able to series DCM or separately excited DCM in the optimal point of efficiency as finding the types of motor having maximum efficiency with torque and speed. By performing high efficiency tracking drive, it is expected that energy consumption of power source with limited energy density would be reduced, and so utility efficiency would be improved.

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Modelling and Analysis of AFPM, RFPM Compound Generator (AFPM, RFPM 복합발전기의 모델링 및 해석)

  • Kim, Jin-Sa
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.7
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    • pp.459-462
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    • 2017
  • In this study, we design, model, and analyze a compound generator that combines the axial flux permanent magnet (AFPM,) and radial flux permanent magnet (RFPM), which is expected to increase power generation by allowing the magnets to be placed on the upper, lower, left, and right sides of the same-sized generator. Through the design, modelling, and analysis of AFPM and RFPM compound generators, the generator load evaluation results rated output of 500.25 W and efficiency of 87.60%, respectively, at a rated speed of 600 rpm. By employing this complex generation system,these findings are expected to contribute to the activation of a small power generation system.

A Study on the Optimal Operation According to Appropriate PCS and Battery Capacity Estimation of PV-BESS System (PV-BESS 시스템의 적정 PCS, 배터리용량 산정에 따른 최적 운영에 관한 연구)

  • Choi, Yun Suk;Na, Seung You
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.9
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    • pp.1174-1180
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    • 2018
  • In December 2017, the government announced plans to increase the current proportion of renewable energy from 7% to 20% by 2030 through a plan called the Renewable Energy 3020 Implementation Plan. Therefore, the demand for installation of photovoltaic(PV), wind turbine(WT) and battery energy storage system(BESS) is expected to increase. In particular, the system combined with energy storage system(ESS) is expected to take up a large portion since PV and WT can receive high renewable energy certificates(REC) weights when combined with ESS. In this study, we calculate the optimal capacity of the power conditioning system(PCS) and the BESS by comparing the economical efficiency and maximize the efficiency of the PV-BESS system in which the PV and the BESS are connected. By analyzing the system marginal price(SMP) and REC, it maximize profits through application of REC weight 5.0 and optimal charge-discharge scheduling according to the SMP changes.

A Study by Proposal of Efficiency Increase for a Full-scale Wastewater Reclamation Facility using a Biofilter Packed with Granular Sulfur (하수처리수 재이용을 위한 실규모 입상황 생물막여과 시설의 효율증대 방안에 관한 연구)

  • Moon, Jin-Young;Hwang, Yong-Woo;Baek, Seung-Ryun
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.1
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    • pp.73-83
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    • 2010
  • This study was performed to increase the removal efficiency of the biofilter packed with granular sulfur in municipal wastewater reclamation facility. Constituent units were influent water tank, denitrification tank, BOD reduction tank and outlet. And, the major operation factor is a biofilter packed with submerged granular sulfur. Actual wastewater and synthetic wastewater were used as influent wastewater. Experimental condition was divided into two phases according to the amount of a phosphorus coagulant. Total phosphorus removal efficiency was insignificant at mode I that phosphorus coagulant was not injected. The average influent and effluent total phosphorus concentrations at mode II were 0.5 ~ 1.0 mg/L and 0.27 mg/L, respectively. As for COD and BOD effluent concentrations, COD was 3.0 mg/L and BOD was 1.0 mg/L. Additionally, nitrogen removal rates were high at low influent DO concentration. In conclusion, a new process, biofilter packed with granular sulfur is expected to treat high-rate nitrogen wastewater and expected to be utilized as an alternative of technological innovation for the nitrogen treatment.

A Study on the Importance Priority of Expected Effect Factors in the Introduction of Cloud Computing Service (클라우드 컴퓨팅 서비스 도입 시 기대효과 요인의 중요도 우선순위 도출에 관한 연구)

  • Kang, Da-Yeon;Kim, Sang-Hyun
    • The Journal of the Korea Contents Association
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    • v.20 no.4
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    • pp.564-570
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    • 2020
  • The development of cloud computing service technologies plays a particularly important role in the enterprise. The introduction of cloud computing services by companies is also contributing to the improvement of market value and changes in corporate earnings. In this study, we demonstrated the importance of priorities by selecting sub-items that can be evaluated by separating the expected characteristics of efficiency, economics, and dependencies when introducing cloud computing services. The main priority items were selected based on prior research and the survey was conducted by IT system experts. Using AHP analysis method, the results of performing a double contrast bridge resulted in the final priority. The findings will later be used as important data to determine an enterprise's decision to accept cloud computing services.

Improvement of Bill of Quantities of Door and Window Work for BIM-based Cost Estimation (BIM 기반 견적을 위한 창호공사 내역 작성체계 개선 방안)

  • Kim, Mi-Hyeon;Jo, Chan-Won;Yun, Seok-Heon
    • Journal of KIBIM
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    • v.10 no.2
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    • pp.12-20
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    • 2020
  • Recently, interest in BIM technology has been growing in the domestic construction market as the number of construction projects requiring the application of BIM technology has increased. The use of BIM allows the use of various visualization functions through 3D models as well as drawing interference review, quantity calculation and integrated management of information. In particular, estimates of construction costs based on BIM can increase work efficiency by reducing the burden of calculating construction costs and managing them. In order to increase the efficiency of BIM-based cost estimates, it is necessary to improve the correlation between the BoQ(Bill of Quantity) information and the BIM model. For this purpose, the ratio of the amount and item to the detailed construction of the current BoQ was analyzed, especially the problem of the calculation of construction cost in the window work in this study. In addition, we would like to suggest a method for systematically linking the BoQ information with the BIM model by improving the BoQ information structure of the window work. It is expected that this will increase the efficiency of the quantity calculation and analysis work of construction cost of window work. In addition, it is expected that this method will help to analyze and predict changes in construction cost of windows and doors by facility characteristics and type.

Maintenance Limit Renewal Policy for Inferiority System based on Opportunity Cost (기회비용을 고려한 열화시스템의 보전한계갱신정책)

  • 박상민;김연수
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.17 no.32
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    • pp.233-242
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    • 1994
  • This study deals with the derivative adverse minimum for inferiority system depends on continuose operating under infinite planning horizon. This planning will be accomplished by maintenance limit renewal policy in consideration of opportunity cost which affects system by failure during operation periods and expected cost under nomal operation states. By the results, we will be expected incresing total efficiency for the system by optimal renewal policy.

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