• KIEAE Journal
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• 제17권3호
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• pp.45-50
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• 2017

Purpose: There have been more researches focused on eco-friendly construction practices in order to save energy consumed and these practices have been extensively applied for constructing buildings. However, researches on energy consumption saving and efficiency for hospital facilities have been still insufficient. This research aims to draw factors that affect energy efficiency of hospital buildings through literature reviews and perform an expert-survey using AHP(Analytical Hierarchy Process) method in order to analyze the importances and priorities of these energy efficient factors. Method: Using the AHP method, this paper suggests the importances and priorities of factors to affect energy efficiency in hospital buildings. The survey of experts at a architectural design and a construction management companies was conducted via e-mail and mail. Result: As a result, factors of window and door, insulation, ventilation, and natural lighting turned out relatively important as respectively 0.104, 0.102, 0.101, and 0.095 n the energy efficiency in hospital buildings, while factors of artificial lighting, geothermal, solar heat, and control did unimportant as 0.027, 0.033, 0.043, and 0.053.

• 한국태양에너지학회 논문집
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• 제25권4호
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• pp.85-92
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• 2005

One of the most effective methods for utilizing solar energy is to combine thermal solar and optical energy simultaneously using a hybrid panel. Many systems using various kinds of photovoltaic panels have already been constructed. But utilizing solar energy by means of a hybrid panel with concentrator has not been to be attempted yet. Normally if sunlight is directed on the solar cell, and there is no increase in temperature, the absorption energy of each cell will increase per unit area. In a silicon solar cell. however, cell conversion efficiency decreases according to the increasing temperature. Therefore, to maintain cell conversion efficiency under normal condition, it is necessary to keep the cell at operating temperature. we design and make new hybrid panel with cooling system to prevent increasing of temperature on cell, collect effectively thermal energy. We compared performance of new hybrid panel with PV module and thermal panel. We also evaluated conversion efficiency, electric power and thermal capacity and confirmed cooling effect from thermal absorption efficiency.

• 대한기계학회논문집A
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• 제39권5호
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• pp.499-505
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• 2015

압전 진동 에너지 수확 장치의 설계 및 성능 평가 시 에너지 변환 효율을 고려하는 것은 매우 당연하다. 본 연구에서 고려하는 에너지 변환 효율은 부하 저항이 부착된 압전 진동 에너지 수확 장치에 입력되는 가진 진동 파워 대비 전기 출력 값으로 정의된다. 기존의 연구에서는 근사적으로 임피던스 정합된 부하 저항에서의 전기 출력을 고려한 반면, 본 연구에서는 최적의 임피던스 정합 값을 사용하여 새롭게 에너지 변환 효율 식을 유도하였다. 유도된 식의 타당성을 검증하기 위해 3 개의 서로 다른 전기-역학 연성 계수 값을 갖는 진동 에너지 수확 장치에 대한 유한 요소 해석 결과를 이용하였다. 또한, 부하 저항의 임피던스 정합 방법의 차이에 따른 에너지 변환 및 변환 효율 특성을 살펴보았다.

• 도시과학
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• 제11권1호
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• pp.15-20
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• 2022

The issue of hotel energy use is growing more significant as the hotel industry expands. It is important to take into account the electrical installation and space-specific features in a room unit in order to comprehend the energy consumption of a hotel guestroom. In light of this, this study aimed to analyze standby power for enhancing the energy efficiency of a hotel guestroom during check-out status. This study was conducted in three steps: (i) data collection; (ii) analysis of energy consumption patterns; and (iii) analysis of energy efficiency improvement plan. The main findings of this study can be summarized as follows. First, 32.24% of energy was used in fan coil unit) during check-out status. Second, a hotel guestroom had a 4.30% energy saving potential, based on energy consumption patterns during check-out status. This study can contribute to support hotel management to operate guestrooms differently by helping them identify patterns in energy use and realize potential savings.

• ETRI Journal
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• 제36권3호
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• pp.506-509
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• 2014

This paper studies the energy efficiency power allocation for cognitive radio networks based on uplink orthogonal frequency-division multiplexing. The power allocation problem is intended to minimize the maximum energy efficiency measured by "Joule per bit" metric, under total power constraint and robust aggregate mutual interference power constraint. However, the above problem is non-convex. To make it solvable, an equivalent convex optimization problem is derived that can be solved by general fractional programming. Then, a robust energy efficiency power allocation scheme is presented. Simulation results corroborate the effectiveness of the proposed methods.

• 설비공학논문집
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• 제10권2호
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• pp.173-179
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• 1998

An experimental study was conducted on the effect of compressor capacity control range of heat pump on the seasonal energy efficiency ratio with variation of the maximum and minimum compressor input frequencies. To obtain seasonal energy efficiency ratio, steady state test at the maximum, minimum and intermediate compressor speed and cyclic test at the minimum compressor speed should be conducted. Maximum input frequency was varied to 95Hz, 105Hz, and 115Hz, and the minimum input frequency was varied to 35Hz, 45Hz, and 55Hz. The seasonal energy efficiency ratio increased as the input frequency of the compressor decreased. The maximum input frequency had only slight effects on the SEER.

• 한국태양에너지학회 논문집
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• 제25권3호
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• pp.47-52
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• 2005

Normally if sunlight is directed on a solar cell without any increasing in temperature, the amount of absorption energy per unit area of each cell is increasing. In a silicon solar cell. however, cell conversion efficiency decreases with the increase of temperature. Therefore, to maintain cell conversion efficiency under normal condition, it is necessary to keep the cell at operating temperature. We tried to design and make new hybrid panel with cooling system to prevent increasing of temperature on cell, collect and use thermal energy more effectively. We compared performance of this new hybrid panel with current thermal panel. We also evaluated conversion efficiency, thermal capacity and confirmed cooling effects from thermal absorption efficiency.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.309-314
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• 2009

The unpredicted worldwide oil price makes the energy efficiency technology be more importance than any other period. The small cogeneration system is one of the most representative technology among the energy efficiency technologies, and the Stirling engine cogeneration system has been concerned and investigated due to the preferable characteristics - low toxic emission, low noise and vibration level, and the various form of fuel. A tiny, 1kW of electrical output, gas fueled Stirling engine cogeneration system was investigated. The electrical efficiency and thermal efficiency of the system were measured. The experiment was executed at an independent Stirling engine mode, independent secondary burner mode, and the combined mode. Part load characteristics of the Stirling engine cogeneration system were investigated also. With the efficiency characteristics, the $O_2$ and NOx emission characteristics were measured.

• 한국수소및신에너지학회논문집
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• 제24권5호
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• pp.373-385
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• 2013

To obtain higher power efficiency of Residential Power Generation system(RPG), it is needed to operate system on optimized stoichiometric ratios of fuel and air. Stoichiometric ratios of fuel/air are closely related to efficiency of stack, reformer and power consumption of Balance Of Plant(BOP). In this paper, optimizing stoichiometric ratios of fuel/air are conducted through systematic experiments and modeling. Based on fundamental principles and experimental data, constraints are chosen. By implementing these optimum values of stoichiometric ratios, power efficiency of the system could be maximized.

• 디지털산업정보학회논문지
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• 제16권1호
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• pp.33-39
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• 2020

A smart grid is a next-generation power grid that can improve energy efficiency by applying information and communication technology to the general power grid. The smart grid makes it possible to exchange information about electricity production and consumption between electricity providers and consumers in real-time. Advanced metering infrastructure (AMI) is the core technology of the smart grid. The AMI provides two-way communication by installing a modem in an existing digital meter and typically include smart meters, data collection units, and meter data management systems. Because the AMI requires data collection units to control multiple smart meters, it is essential to ensure network availability under heavy network loads. If the load on the work done by the data collection unit is high, it is necessary to allocation new data collection units to ensure availability and improve energy efficiency. In this paper, we discuss the allocation scheme of data collection units for the energy efficiency of the AMI.