• 한국유체기계학회 논문집
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• 제14권3호
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• pp.28-32
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• 2011

The inverter rotary compressor discharges refrigerant and compressor oil in air-conditioning systems. The compressor oil which discharged form compressor decreases the efficiency of heat exchanger and affects the compressor operation. Recently, several studies are in progress for reducing the compressor oil. Before the reduction of compressor oil discharge rate, the quantitative measurement and evaluation method are required. In order to cope with this requirement we have developed the measurement technic of oil discharge rate. The reliability assessment was carried out approximately 0.1% of the errors with compressor performance indicators. The acceptable errors were to ensure the reliability of measurement technic. In the experiment results at several conditions, The oil discharge rate of heating operation has been confirmed average 3.7 times more than cooling operation. In this study the evaluation method and the experimental results of oil discharge rate in air-conditioning systems are presented with various operating conditions.

• 전기학회논문지
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• 제64권10호
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• pp.1411-1417
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• 2015

The installation of PV system to the power distribution system is being increased as one of solutions for environmental pollution and energy crisis. However, the efficiency of PV system is getting decreased because of the aging phenomenon and several operation obstacles. Therefore, The technology development of aging diagnosis of PV modules are required in order to improve operation performance of PV modules. This paper proposes evaluation algorithm for aging state in PV modules by using the electrical characteristics of PV modules and environmental factors. And also, this paper presents a operation evaluation system of PV modules based on the proposed aging diagnosis algorithm of PV modules. From the simulation results of proposed evaluation system, it is confirmed that the proposed algorithm is a useful tool for aging diagnosis of PV systems.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2127-2137
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• 2017

A virtual power plant (VPP) is a system that virtually integrates power resources based on the VPP participating customer (VPC) unit and operates as a power plant. When VPP operators manage resources to maximize their benefits, load reduction instructions may focus on more responsive VPCs, or those producing high profitability, by using VPC resources with high operation efficiency. VPCs may thus encounter imbalance problems during operation. This imbalance in operation time would bring more participation for some VPCs, causing potential degradation of their resources. Such an operation strategy would be not preferable for VPP operators in managing the relationship with VPCs. This issue impedes both continual VPC participation and economical and reliable VPP operation in the long term. An operation algorithm is therefore proposed that considers the operation time of VPC generators for mandatory reduction of power resource consumption. The algorithm is based on constraints of daily and annual operation times when VPP operators of local generators perform capacity-market power transactions. The algorithm maximizes the operator benefit through VPP operations. The algorithm implements a penalty parameter for imbalances in operation times spent by VPC generators in fulfilling their obligations. An evaluation was conducted on VPP operational effects by applying the algorithm to the Korean power market.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.2215-2222
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• 2010

Advanced EMU have been enhanced in terms of safe transport and maintainability. It is a new urban railway technology that enables an operation institution to cut repair and maintenance costs and customers to use convenient service at lower costs based on IT technology. If a development vehicle of Advanced EMU is completed, it will be used to test the entire advanced EMU system through sufficient performance check and reliability check prior to operation in commercial line. It will also verify efficiency, safety, punctuality and energy efficiency of transport. Accordingly, it is necessary to figure how to repair and maintain vehicles to enhance safety of Advanced EMU system in cooperation with operation during the period of comprehensive evaluation on the operation of a development vehicle in a test line. In this paper, we investigated the maintenance program of Advanced EMU on test operation in Dabul line. The test condition and operation environment of Advanced EMU in Daebul line was analyzed.

• 한국조명전기설비학회지:조명전기설비
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• 제9권2호
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• pp.50-57
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• 1995

본 논문에서는 지능망설비의 성능평가를 위한 평가모델 분석과 현재 운용 중인 지능망서비스 설비시스템에 적용하여 성능평가 모델 및 평가결과를 제시하였다. 평가 기법에는 시뮬레이션 및 운용해석 방법을 이용하였다. 평가 결과로서, 시뮬레이션과 운용해석 방법의 결과는 대체로 일치하였으며 지능망설비의 지연요소 보다 이용자-망 상호작용시간이 더 큰 영향을 주고 있음을 알 수 있었다. 본 논문에서 제안한 평가모델에서 지능망서비스 설비구조의 특성상 서비스처리용량을 확장할 수 있었고 서비스 성능을 고려한 정보통신설비 계획시 또는 서비스 운용관리시에 유용한 성능예측 기법으로 제공될 수 있으며 지능망서비스 설계시 서비스 성능을 고려한 통신설비 설계에 유용하게 이용되리라 기대된다.

• 정보통신설비학회논문지
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• 제10권1호
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• pp.33-39
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• 2011

This paper considers a performance analysis of set-top box (STB) power saving schemes. STB converts the signal into content which is then displayed on the television (TV) screen, and there are typically two operation modes: on mode and stand-by mode. The total energy consumption (TEC), a typical measure of power consumption of STB, is defined by the sum of power consumption in each mode. Recently there are some works of STB power saving schemes that transit STB operation modes efficiently, and the mode transition time point of those schemes can be different. Thus it is required to develop a performance evaluation method that reflects mode transition time points of each scheme to get TEC correctly. This paper proposes a performance evaluation method for STB power consumption using Poisson process to consider the mode transition time point. By modeling STB mode transitions as events of Poisson process, the average time duration of STB mode is computed and accordingly the effect of power saving is evaluated. The performance evaluation result shows that the proposed method achieves 1 to 19% improvement in power consumption compared with a conventional performance evaluation method.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.597-601
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• 2006

The advantages of solar energy are that it is renewable, infinite supplied and environmentally safe energy source. However, solar energy related products have the problems such as the limitation for installation, problems in maintenance and insufficient reliability which have been the barrier to consumers to satisfy the purchase need for solar heat related products. In this regard, in order to support the solar energy related companies the necessity for various technical information required for the commercialization of new products such as various performance test necessary for the certification of solar energy system, standardization for facilities and products, performance evaluation method and the measurement of performance is suggested. The purpose of this paper is to design the monitoring system for positive tests of system linked household hot water system using solar heat out of various solar energy systems, to establish an analysis and monitoring system for performance maintenance and operation technique, and to configure the centralized detection network by utilizing remote monitoring system. This research also aims at conducting monitoring for operation and performance evaluation in relation to database establishment and analytical evaluation and at describing the method of enhancing the reliability of solar energy system through the development of performance evaluation program.

• 융합보안논문지
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• 제19권2호
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• pp.129-136
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• 2019

지상작전 시 지휘관 및 참모의 주된 업무는 지속적으로 발생되는 상황에 대처하기 위해 수행되는 의사결정의 연속이라고 볼 수 있다. 하지만 현재의 의사결정 과정은 지휘관 및 참모의 정성적인 방법에 의존하고 있기 때문에 제4차 산업혁명을 기반으로 현재 및 미래에 도입되고 있는 의사결정 도구와의 연결을 보장하기 어려운 실정이다. 본 연구에서는 지상작전과 연관된 의사결정 고려요소들의 정량화에 대해 전장정보분석(IPB) 시 접근로 평가요소들의 상대적 중요도를 AHP를 이용하여 도출하는 것을 중심으로 제시된다. 전장정보분석에서 가장 중요한 과정 중에 하나가 접근로에 대한 평가이며, 평가요소에는 목표 접근성 관측과 사계 은폐와 엄폐 장애물, 기동의 용이성 인접 접근로로의 전환 용이성을 포함하고 있다. 기존의 방식은 비교요소에 의한 방법과 장단점에 의한 비교가 있지만, 위 평가요소들의 중요도가 동등하게 적용된다는 문제점이 항상 제기되어 왔다. 전문가집단을 통한 분석적계층과정(AHP) 기법을 적용하였고, 분석결과 목표 접근성이 가장 중요한 평가요소임을 확인할 수 있었다.

• 상하수도학회지
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• 제19권4호
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• pp.473-479
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• 2005

Applying enhanced coagulation is not uncommon not only to improve water quality but also to obtain economical advantages in water treatment. In this study, the economical evaluation was investigated with considering dosage of coagulant, produced sludges and usage of activated carbon with two different water sources. To simulate the granular activated carbon(GAC) adsorber mini-column test was adapted. Even if there were some variation according to the source waters, the life time of GAC was extended 60 to 110days with adding 2.5 to 3 times of coagulant in enhanced coagulation. With assumption of changing GAC adsorber at 50% of breakthrough the total treatment cost can be reduced to range from 25% to 44% with adapting the enhanced coagulation. The obtained value can not be generalized because the value can be varied by water quality and cost of the GAC or coagulant. However, the evaluation can be basis starting point to find optimum operation methods for the drinking water treatment which has plan to adapt GAC adsorber.

• 공학교육연구
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• 제16권3호
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• pp.79-86
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• 2013

The purpose of this study was to analyze the factors related to the satisfaction of the introductory engineering education program for the employees, who majored liberal arts or commerce, among the educational programs for industrial workers which are performed as an effort to spread the performance of the Innovation Center for Engineering Education, and reinforce the competitiveness through effective program operation. This study was performed on the basis of CIPP evaluation model (context, input, process, product). A factorial analysis and a regression analysis were conducted based on a survey made on 87 persons who completed the introductory engineering education program among the employees of D group who majored liberal arts or commerce. It is expected that this study will contribute toward suggesting the implications for designing and operating the educational programs for industrial workers in order to find out the important factors of satisfaction and to conduct the education operation with professionalism.