• KIEAE Journal
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• 제16권6호
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• pp.143-149
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• 2016

Purpose: This study is to analyze the characteristics of energy usage in apartment houses that had built for 20 years recently in capital area and the correlation between the characteristics of energy usage and the regulation of energy efficiency in building. Method: It is investigated 264 apartment sites having been built since 1991 where 312,071 houses live. The sites were listed on Naver map. Quantities of energy usages in the sites were searched in a portal, Green Together being operated by the Ministry of Land, Infrastructure and Transport. The appraisal report of building energy in the portal is recording usage quantity of gas energy, district cooling & heating energy, electric energy, total energy, 1st gas energy, 1st district cooling & heating energy, 1st electric energy, 1st total energy, etc. Result: Analyzing the average of total energy usage from 1991 to 2012, the average in 2001, 2008 each was reduced more than 10 percent compared to the previous year. It was analyzed that the reduction was relevant to building energy-saving design criterion which have been tightened more than before.

• 한국태양에너지학회 논문집
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• 제28권3호
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• pp.45-52
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• 2008

In order to clarify characteristics of variation in wind energy over a long-term period, an investigation was carried out at Seoguang site on Jeju island. The wind data for 10 years from Automatic Weather System (AWS) were analyzed for each year. The variation in the annual energy production (AEP) for the 2 MW wind turbine was estimated through statistical work. The result shows that the range of the yearly average wind speed at 15 m above ground level for 10 years was from -22.6% to +13.7%, which is wider range than that in Japan. The coefficient of variation for the AEP was 22.7%, which is about twice of that for the yearly average wind speed. Therefore, for estimating the wind energy potential accurately at a given site, the wind data should be analyzed over a long-term period based on the data from the meteorological station.

• KIEAE Journal
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• 제16권2호
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• pp.23-31
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• 2016

Purpose: Recently energy consumption is rapidly increasing due to continuous development of social evolution in various field. In this situation, there is a lot of effort to reduce this energy consumption in many ways, especially in building energy. Preceding studies already started to analyze the housing area such as zero energy house and passive house by researching annual building energy consumption, but to apply the results of housing to office building is insufficient since it has different consumption tendency. Method: In this study, eQuest program was used for simulation and the base model is selected among standard office building in ASHRAE 90.1. Variables are divided into passive and active factors for comparison. Result: In passive factors, glazing system showed the highest energy saving rate by 21.3% with triple low-e glass and enhancing wall u-value showed the lowest energy saving rate by 3.6% with 0.15 m2/K. In active factors, VAV system showed 30.9% energy saving rate when compared to CAV system, and heat exchanger showed 10.2% energy saving rate. For regeneration energy part, photovoltaic panel generated 10.4% of base annual energy usage.

• Asian-Australasian Journal of Animal Sciences
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• 제21권7호
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• pp.1038-1047
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• 2008

This study aimed at targeting fixed increases in body weight (100 g/wk) by quantitatively regulating energy allowances (ME) in broiler breeders from 5 to 20 wks of age. Four energy regimes were tested: 1. The energy required for maintenance, activity and growth was calculated for 100 g increases in body weight/wk and a measured quantity of grower diet (160 g protein and 2,600 kcal ME/kg) was offered to the control group (ME-100) to achieve the anticipated weight gain. The energy allowances increased with age from 132 to 294 kcal/d. 2. Additionally, three energy regimes were considered, quantitatively reducing ME by 10% (ME-90) or 20% (ME-80) and increasing by10% (ME-110) over the control group. Each test group had 23 replicates5 female chicks housed in cages. The influence of energy regimes and age on growth, nutrient digestibility, carcass attributes, bone parameters and stress was evaluated at 4 wk intervals. Quantitative ME restriction by 10% (119-265 kcal/d) produced an average weight gain of 98.1 g/wk, which was closer to the targeted increase of 100 g/wk, whereas the control group attained it nine days earlier. Restriction of energy by 10 or 20% produced better conversion efficiency of feed, energy and protein and apparent digestibility of protein, Ca and P than 10% excess ME. Energy regimes did not influence eviscerated meat yield, but higher energy allowances (ME-110) significantly increased abdominal fat pad and liver weights and decreased giblet weight, percent muscle protein and tibia ash. Relatively higher stress was recorded in ME-restricted groups, as reflected by wider heterophil and lymphocyte ratios and increased bursa weight. Early age (5-12 wk) significantly influenced bone mineralization, conversion efficiency of feed, energy and protein and apparent digestibility of protein, Ca and P, while later ages (13-20 wk) increased eviscerated meat yield, abdominal fat, tibia weight and muscle protein and reduced stress. Energy regime x age interactions were significant and are discussed. In conclusion, the synthetic broiler line used in our study responded positively to controlled energy feeding during the rearing period. Breeders offered 119-265 kcal/d, a reduction of 10% energy over the control group, were more effective in regulating grower performance than the latter. In addition to energy regimes, age intervals also exhibited significant influence on specific parameters during the grower phase.

• 한국세라믹학회지
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• 제42권1호
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• pp.62-68
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• 2005

질화상압동시소결(NPS) 공정에 의해 제조된 기공율이 다른 질화규소 소결체에 대해 $1300^{circ}C$ 순산소 가스분위기에서 산화거동을 조사하였다. 질화규소 세라믹스 표면에 형성된 산화층의 두께는 산화 시간과 온도에 따라 증가되었으며, $1300^{circ}C$에서 100시간 산화시킨 5A5Y5Si와 5A5Y10Si 시편의 산화층 두께는 각각 10$\mu$m와 20$\mu$m이었다. 5A5YSi와 5A5Y10Si 시편의 산화는 각각 215kJ/mol과 104kJ/mol의 활성화 에너지를 갖고 포물선적 거동을 나타내었다. $1300^{circ}C$에서 500시간 산화시킨 후, 5A5Y5Si 시편에 대해 꺾임 강도를 측정한 결과, 초기의 약 500MPa값을 유지하고 있었으며, 반면 5A5Y10Si의 경우에는 초기의 값에서 약 100MPa의 강도저하를 나타내고 있었다.

• 지식경영연구
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• 제24권1호
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• pp.195-221
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• 2023

전 세계적인 에너지·기후 위기는 각국의 이해관계가 복잡하게 얽혀있어 글로벌 대응이 필수적인 아젠다임이 최근 다시금 환기되고 있다. 특히, 우리나라는 에너지 수입의존도가 높고 에너지 다소비·저효율 소비 및 온실가스 다(多) 배출구조가 지속되고 있어 에너지효율 및 탄소중립 달성을 위한 혁신적이고 실효성 있는 에너지정책이 절실하다고 하겠다. 본 연구에서는 우리나라에 1980년대 중반 집단에너지 방식이 도입된 이후의 분산형 집단에너지 정책변동 중 "국가 열(熱) 지도 사업" 정책 추진사례를 수정 다중흐름모형으로 분석하고자 한다. 연구 대상 기간인 이명박-박근혜 정부의 10년간은 에너지정책의 주된 패러다임이 "분산형 에너지플랫폼"으로 전환하는 데 있어 정책의제 설정과 정책 표류, 정책수정의 전환이 이루어졌던 기간으로서 연구에 의미가 있을 것이다.

• Journal of Semiconductor Engineering
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• 제1권1호
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• pp.31-37
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• 2020

We present an approximate DRAM architecture for energy-efficient deep learning. Our key premise is that by bounding memory errors to non-critical information, we can significantly reduce DRAM refresh energy without compromising recognition accuracy of deep neural networks. To validate the key premise, we make extensive Monte-Carlo simulations for several well-known convolutional neural networks such as LeNet, ConvNet and AlexNet with the input of MINIST, CIFAR-10, and ImageNet, respectively. We assume that the highest-order 8-bits (in single precision) and 4-bits (in half precision) are protected from retention errors under the proposed architecture and then, randomly inject bit-errors to unprotected bits with various bit-error-rates. Here, recognition accuracies of the above convolutional neural networks are successfully maintained up to the 10^-5-order bit-error-rate. We simulate DRAM energy during inference of the above convolutional neural networks, where the proposed architecture shows the possibility of considerable energy saving up to 10 ~ 37.5% of total DRAM energy.

• 한국기계가공학회지
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• 제16권1호
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• pp.70-76
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• 2017

The pollution problem of fossil energy sources has caused the development of green energy harvesting systems. Piezoelectric energy harvesting technology has been developed under those external environmental factors. A piezoelectric energy harvester can be defined as a device which transforms mechanical vibration or impact energy into electrical energy. Most researches have focused on bender structures. However, these have a limitation on energy efficiency because of the small effective electromechanical coupling factor, around 10%. Therefore, we should look for a new design for energy harvesting. A cymbal energy harvester can be a good candidate for the high-power energy harvester because it uses a high amplification mechanism using endcaps while keeping a higher electromechanical coupling factor. In this research, we focused on energy efficiency improvements of the cymbal energy harvester by changing the polarization direction, because the electromechanical coupling factor of the k33 mode and the k15 mode is larger than that of the k31 mode. Theoretically, we checked the cymbal harvester with radial polarization and it could obtain 6 times larger energy than that with the k31 direction polarization. Furthermore, we verified the theoretical expectation using the finite element method program. Consequently, we could expect a more efficient cymbal harvester with the radial polarization by comparing two polarization directions.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.1-6
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• 2018

In this study, the energy consumption of the typical floor was compared by the total energy comsumption of the building in highrise building. In gerneral, many researchers are studying on the typical floor in highrise buildings for avoiding complexity in energy simulation. But few papers are studied on energy consumption along the floors. In the model bulding, the energy consumption data were acquired by BEMS system in 2011. According the data, the total net energy consumption was $193.99kWh/m^2$ for all area and the total net energy consumption was $247.61kWh/m^2$ for HVACR area. The total electricity and gas energy are used 47.7% for heating and cooling, 33.5% for lighting and plug, 12.9% for conveyance power and 5.9% for restaurant. In comparison of only ground floor, amount of energy consumption in the lobby is 10%, and 90% of total energy consumption is used in the typical floor. For this result, energy simulation on the typical floor is acceptable for calculating the total energy consumption in the highrise building.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1723-1729
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• 2021

Energy and directional distribution of neutrons at the Beloyarsk NPP workplaces is a subject of this study. Measurements of H^*(10) rate and neutron energy distribution were taken at 8 workplaces, which can be divided into three categories: work with spent or fresh nuclear fuel, work with radionuclide neutron sources, work at the rooms adjusted to reactors. The Hp(10) measurements were performed only at 6 out of 8 locations, due to the fact that long term placing of an effective neutron moderator in fresh nuclear fuel storage facility is forbidden. As a result of the research energy and direction distribution of the neutron fields at 8 locations of the Beloyarsk NPP workplaces was obtained. To estimate the accuracy of the H^*(10) rate and Hp (10) measurements the reference values of dose equivalents were calculated using energy and directional distribution. To take into account the difference between the reference values and the measured results site-specific correction factors were calculated.