• 전기전자학회논문지
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• 제23권2호
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• pp.380-387
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• 2019

최근 태양열의 열 취득과 태양광의 전기에너지 취득의 상호 보완으로 태양광열(PV/T) 연구가 활발히 진행되고 있으며 대체로 PV/T의 에너지 효율이 더 높은 것으로 연구되고 있다. 본 연구에서는 대상 건물을 모델링하여 연간 에너지 수요량을 산정하고 옥상면에 PV/T를 설치하여 PV/T와 PV의 에너지 생산량을 시뮬레이션별 Case로 비교 분석 하였다. 결과로 남부지방인 부산광역시의 에너지 생산량이 가장 많았다. 또한 에너지 수요량에서 남는 에너지 생산량을 에너지 공유 시스템의 도입을 가정하였을 때 에너지 공급 가능 세대수를 산정한 결과 최대 3.3세대로 나타났다.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.55-60
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• 2022

As interest in sustainable and eco-friendly energy sources is increasing due to various problems in the carbon society, a hydrogen economy using hydrogen as a main energy source is emerging. While the natural gas reforming method generates carbon dioxide, the water electrolysis method based on renewable energy is eco-friendly. The water electrolysis device currently being developed uses a 2 Nm³/hr class alkaline aqueous solution as an electrolyte and produces hydrogen based on renewable energy. In this study, risk assessment was conducted for these water electrolysis devices

• 대한지역사회영양학회지
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• 제23권1호
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• pp.60-72
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• 2018

Objectives: This study was conducted to investigate the awareness of energy drinks, energy drink consumption behaviors, and associated factors among college students. Methods: A total of 536 students from three universities in Cheongju completed a self-administered questionnaire regarding awareness and consumption of energy drinks as well as general characteristics, health-related characteristics, and eating habits. Results: Approximately half of the respondents reported they knew what energy drinks were, while 45.7% had heard of energy drinks but did not know what they were. However, 76.9% had experience in using energy drinks. The main reason for using energy drinks was to stay awake, and the main place that they were used was on campus or at the library. More than 70% of energy drink users did not read the caffeine contents of energy drinks. After consuming energy drinks, 31.3% experienced adverse effects, the most serious being sleep disturbance. Approximately 33% of students consumed energy drinks once a month or more frequently, and men consumed energy drinks more frequently than females. Energy drink users who consumed at least one drink each month were more likely to be natural science major or drink more milk for male students, and to have more allowances or consume less meat for female students, compared with non-users. Conclusions: Our study showed that 33% of students consumed at least one energy drink each month, and there were a small number of students consumed energy drinks almost every day or energy drinks mixed with alcohol. Accordingly, college students should be taught potential health hazards of energy drinks mixed with alcohol as well as energy drinks alone. In addition, reading labels about caffeine and sugar contents in energy drinks is encouraged.

• Electronic Materials Letters
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• 제14권6호
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• pp.718-724
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• 2018

With the development of photovoltaic industry, the cost of photovoltaic power generation has become the significant issue. And the metallization process has decided the cost of original materials and photovoltaic efficiency of the solar cells. Nowadays, double printing process has been introduced instead of one-step printing process for front contact of polycrystalline silicon solar cells, which can effectively improve the photovoltaic conversion efficiency of silicon solar cells. Here, the relative cheap Cu paste has replaced the expensive Ag paste to form Ag/Cu composite front contact of silicon solar cells. The photovoltaic performance and the cost of photovoltaic power generation have been investigated. With the optimization on structure and height of Cu finger layer for Ag/Cu composite double-printed front contact, the silicon solar cells have exhibited a photovoltaic conversion efficiency of 18.41%, which has reduced 3.42 cent per Watt for the cost of photovoltaic power generation.

• 한국태양에너지학회 논문집
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• 제36권6호
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• pp.13-24
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• 2016

The government introduced a mandatory installation system of new & renewable energy for public building to meet the target of greenhouse gas reduction and also suggest a correction factor for new renewable energy to expand the installation of various new & renewable energy systems. The introduction of correction factors, however, was followed by the reduction of installation size of new & renewable energy sources. Assuming that it was caused by a correction factor for each new renewable energy source calculated by the initial costs, this study proposed a new correction factor approach based on payback periods to reflect the technology element in the calculation process of correction factors additionally. The application results of new correction factors show that it was possible to do complex calculations including the economic and technological aspects to select a new & renewable energy system and that the installation size was also enlarged.

• Carbon letters
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• 제20권
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• pp.47-52
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• 2016

Physical and electrochemical qualities were analyzed after KOH activation of a direct methanol fuel cell using needle coke as anode supporter. The results of research on support loaded with platinum-ruthenium suggest that an activated KOH needle coke container has the lowest onset potential and the highest degree of catalyst activity among all commercial catalysts. Through an analysis of the CO stripping voltammetry, we found that KOH activated catalysis showed a 21% higher electrochemical active surface area (ECSA), with a value of 31.37 m² /g, than the ECSA of deactivated catalyst (25.82 m² /g). The latter figure was 15% higher than the value of one specific commercial catalyst (TEC86E86).

• 한국컴퓨터정보학회논문지
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• 제22권3호
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• pp.115-122
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• 2017

In this paper, we propose an adaptive data aggregation and compression scheme for wireless sensor networks with energy-harvesting nodes, which increases the amount of data arrived at the sink node by efficient use of the harvested energy. In energy-harvesting wireless sensor networks, sensor nodes can have more than necessary energy because they harvest energy from environments continuously. In the proposed scheme, when a node judges that there is surplus energy by estimating its residual energy, the node compresses and transmits the aggregated data so far. Conversely, if the residual energy is estimated to be depleted, the node turns off its transceiver and collects only its own sensory data to reduce its energy consumption. As a result, this scheme increases the amount of data collected at the sink node by preventing the blackout of relay nodes and facilitating data transmission. Through simulation, we show that the proposed scheme suppresses the occurrence of blackout nodes and collect the largest amount of data at the sink node compared to previous schemes.

• 대한임베디드공학회논문지
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• 제11권4호
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• pp.243-249
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• 2016

Energy-harvesting nodes in wireless sensor networks(WSNs) can be exhausted due to a heavy workload even though they can harvest energy from their environment. On contrast, they can sometimes fully charged, thus waste the harvested energy due to the limited battery-capacity. In order to utilize the harvested energy efficiently, we introduce a selective data compression and transmission range control scheme for energy-harvesting nodes. In this scheme, if the residual energy of a node is expected to run over the battery capacity, the node spends the surplus energy to exploit the data compression or the transmission range expansion; these operations can reduce the burden of intermediate nodes at the expanse of its own energy. Otherwise, the node performs only basic operations such as sensing or transmitting so as to avoid its blackout time. Simulation result verifies that the proposed scheme gathers more data with fewer number of blackout nodes than other schemes by consuming energy efficiently.

• Advances in Energy Research
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• 제3권1호
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• pp.11-30
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• 2015

The covenant of Mayors initiative includes the commitment of the municipalities-signatories to reduce voluntarily the greenhouse gas emissions over 20--- by 2020 within their boundaries and obligates them to develop and submit an energy consumption analysis and a sustainable energy action plan within a year from the adhesion. The present paper discusses the energy profile of three medium-sized north-eastern Greek Municipalities (Kavala-MoK, Alexandroupolis-MoA, Drama-MoD) through the analysis of their municipal energy balance. The results of the total final energy consumption per capita include 14.10MWh/capita, 14.24MWh/capita and 12.91MWh/capita for MoK, MoA and MoD respectively. The analysis highlighted the increased energy consumption of the private sectors, namely residential and tertiary building sand private transport. The assessment of the municipalities' energy profiles along with examination of national regulations and action plans and investigation of best available practices within the Covenant of Mayors shaped the development of the sustainable energy action plans of the examined municipalities that is presented in this paper. The proposed pathway towards low-carbon municipalities can be considered a representative case study and a starting point for other municipalities with similar characteristics.

• 설비공학논문집
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• 제27권8호
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• pp.432-439
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• 2015

Current building procedures seek to minimize external air supplies to reduce the energy consumption of air conditioning, resulting in a high dependency on mechanical ventilation. We therefore studied an economizer-cycle system, whereby the introduction of external air saves energy. We analyzed different economizer-control methods, addressing mixed-air temperatures and outdoor-air fractions according to outdoor-air temperatures; also, we analyzed the energy consumption of the three economizer-cycle control types using detailed EnergyPlus simulation modeling. A differential enthalpy control method showed a lower energy consumption range from 5.8% to 6.2% than that of other methods during the simulated period. A differential dry-bulb control method showed a 12.7% lower energy consumption than the no-economizer method in the intermediate period, but also showed 7.1% more energy consumption during the summer period. When latent heat was not removed due to high summer humidity, we found a significant level of resultant energy consumption.