• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.282-291
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• 1999

Lactic acid bacteria were isolated from Kimchi and screened for bacteriocin. A total of 99 strains showed antimicrobial activity when grown on solid media, yet only 10 showed antimicrobial activity in liquid media. Strain H-559, identified as Lactococcus lactis subsp. lactis, exhibited the strongest inhibitory activity and was active against pathogenic bacteria including Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus as well as other lactic acid bacteria. The antimicrobial substance produced by L. lactis subsp. lactis H-559 was confirmed to be a bacteriocin by the treatment of $\alpha$-chymotrypsin, and protease type Ⅸ and ⅩIV. The bacteriocin activity remained stable between pH 2.0 and pH 11.0 and during heating for 10 min at $100^{\circ}C$. The bacteriocin production started in the exponential phase and stopped in the stationary phase. L. lactis subsp. lactis H-559 showed the highest bacteriocin activity at a culture temperature of $25^{\circ}C$, and an inverse relationship between the bacteriocin productivity and mean growth rate at different culture temperatures was observed. The mean growth rate and bacteriocin productivity of L. lactis subsp. lactis H-559 increased as the initial pH of the media increased.

• Journal of Biosystems Engineering
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• 제25권3호
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• pp.221-226
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• 2000

Hot air heater with light oil burner is the most common heater for greenhouse heating in the winter season in Korea. However, since the thermal efficiency of the heater is about 80∼85%, considerable unused heat amount in the form of exhaust gas heat discharges to atmosphere. In order to capture this exhaust heat a heat recovery system for plant bed heating in the greenhouse was built and tested in the hot air heating system of greenhouse. The heat recovery system is made for plant bed or soil heating in the greenhouse. The system consisted of a heat exchanger made of copper pipes, ${\Phi}12.7{\times}0.7t$ located in the rectangular column of $330{\times}330{\times}900mm$, a water circulation pump, circulation plastic pipe and a water tank. The total heat exchanger area is 1.5$m^2$, calculated considering the heat exchange amount between flue gas and water circulated in the copper pipes. The system was attached to the exhaust gas path. The heat recovery system was designed as to even recapture the latent heat of flue gas when exposing to low temperature water in the heat exchanger. According to the performance test it could recover 45,200 to 51,000kJ/hr depending on the water circulation rates of 330 to $690\ell$/hr from the waste heat discharged. The exhaust gas temperature left the heat exchanger dropped to $100^{\circ}C$ from $270^{\circ}C$ by the heat exchange between the water and the flue gas, while water gained the difference and temperature increased to $38^{\circ}C$ from $21^{\circ}C$ at the water flow rate of $690\ell$/hr. By the feasibility test conducted in the greenhouse, the system did not encounter any difficulty in operations. And, the system could recover 220,235kJ of exhaust gas heat in a day, which is equivalent of 34% of the fuel consumption by the water boiler for plant bed heating of 0.2ha in the greenhouse.

• KIEAE Journal
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• 제10권4호
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• pp.45-50
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• 2010

This study for middle school facilities is second following the study of the energy consumption of primary school facilities. There is not on the analysis of the current energy usage for middle school facilities in nations to set goals of energy reduction. Therefore, The purpose of this study is to present various analysis result of energy consumption which is a statistical analysis of domestic middle school facilities in South Korea. As a consequence, each average energy consumption at the domestic middle school facilities analyzed as following after changing as unit 'kWh' only for comparison with every energy source. It represents that the energy consumption of electric power was 183.7MWh(70.2%), gas consumption for heating was 46.5MWh(17.8%), oil consumption was 26.5MWh(10.1%), district energy was 5.1MWh(1.9%). This result describes that consumption of electric power was large greatly and it reflects the expectation that it will climb the demand regarding this energy in the future. In additionally, it analyzed average energy consumption with $74.4kWh/m^2$ by the unit area of air-conditioning and the district which has large energy consumption was Seoul with $91.6kWh/m^2$.

• 한국지열·수열에너지학회논문집
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• 제15권1호
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• pp.1-8
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• 2019

In this study, the effect of operating conditions of fan-coil unit with an oval tube type heat exchanger on its non-dimensional performance coefficient has been investigated. Pressure drops and heat transfer rates were measured under heating condition for various water flow rates, inlet temperatures and wind speeds. As a non-dimensional performance coefficient, Colburn j-factor was evaluated. The results show that the most sensitive parameter on heat flux is the inlet temperature, which affects the heat flux 4.7 and 7.2 times more than the wind speed and water flow rate, respectively. On the other hand, the Colburn j-factor as a non-dimensionalized index decreases with the wind speed, and has an maximum when the wind speed is about 1 m/s. the Colburn j-factor increases slowly with the water flow rate and inlet temperature but at a certain range of inlet temperature, the opposite phenomenon is found.

• 한국축산시설환경학회지
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• 제7권1호
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• pp.1-12
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• 2001

조기이유 자돈용 액상사료 지동 급이기를 개발하기 위하여 물 가열 및 배출부, 가루사료 저장 및 배출부, 혼합부, 약상사료 이송부와 이들의 각 기능을 제어하는 중앙 제어부 및 급이기로 구성 하였다. 이러헥 개발한 조기이유 자돈용 액상사료 자동급이기의 실용성을 검토하기 위해 평균 19일령에 이유한 삼원교잡종(Lw$\times$D)ㅈ돈 18두(남9,여9)를 공시하여 3주 동안 액상으로 급여한 후 3주 동안 가루사료를 무제한 급여하였다. 결과는 아래와 같다. 개발한 액상사료 자동 급이기의 물 가열 및 배출부는 혼합부에 온수를 초당 27$m\ell$, 가루사료 저장 및 배출부는 가루사료를 초당 3.7g 씩 정확하게 중앙제어부의 작동에 따라 이송하였다. 일당증체량은 NRC의 표준 성장률과 비교해 액상사료를 급여한 3주 동안 자돈들이 10%정도 낮은 수준이었으나, 그후 가루사료를 급여한 3주 동안에는 24%, 시험전기간 17% 정도 높은 수준이었다. 사료요구율은 시험개시 후 3주 동안 1.09, 그 후 3주동안 2.14, 시험전기간에는 1.89 이었다. 설사 발생은 액상사료 급여후 3일부터 7일 까지 5일동안 발생하였고, 폐사 자돈은 없었다. 새로이 개발한 액상사료 자동 급이기 시작품의 성능 검정을 위한 예비적 시험으로 19일령에 이유한 자돈에게 적용해 본결과, 액상사료 자동급이기는 어떠한 문제없이 잘 작동되었으며, 자돈들의 액상사료 급여 초기 성장은 부진하였으나 차후 성장 촉진과 사료 이용율이 개선되는 것으로 나타났다. 따라서 본 연구에서 새로이 개발한 액상사료 자동 급이기를 이용한 자돈 사육이 가능할 것으로 사료 된다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.245-250
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• 2008

This study is on the availability of solar thermal energy in Korean high-rise apartment complex depending on the installation type of solar collectors to roof or facade of building. Firstly, solar access evaluation on the roof and the facade of apartment buildings was carried out. The total thermal load of each apartment unit and building was investigated and matched with the energy which was produced by solar thermal systems on the facade. The considered layout patterns of apartment buildings were '一type', 'alternative 一type', 'ㄱtype' and 'ㅁtype' and that was analyzed in prior studies. Extensive dynamic hourly energy simulations with the solar thermal system were Performed with the TRNSYS of SEL. We assumed that the apartment complex is composed of 9 buildings and located in Daejeon. The collectors are the heat-pip evacuated tube collectors and the number of collectors are 45 tubes We assumed that the collectors are installed on the balcony of each unit and the angle of incilnation is $90^{\circ}$. As a result, the supply amount of solar thermal systems is about 4,850,086kJ/hr and the solar fraction is about 66%. The solar fraction according to each azimuth is about 66% on the south, 62% on the south-east $30^{\circ}$ and 56% on the south-east $60^{\circ}$. So, we quantitatively got a line on the optimal azimuth for installing the solar thermal systems. The solar fraction has differences from 5% to 15% of each floor, 6th, 12th and 20th and those tendencies are same in analyzed each 4 types of the apartment complexes.

• Nuclear Engineering and Technology
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• 제25권3호
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• pp.413-423
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• 1993

본 논문에서는 경수로 노심 용융사고시 1차계통의 압력이 높은 경우에 발생하는 격납용기 직접가열 현상에 대한 실험연구를 하였다. 실험은 고리 1,2호기와 영광 3,4호기의 1/30 축소규모와 고리 1,2호기의 1/20 축소규모를 실험모형으로 하여 수행되었으며, 고리 1,2호기의 경우 축소 규모에 따른 검증도 시도하였다. 실험의 주요 변수는 초기 압력 용기의 압력, 파열면적 및 캐비티의 구조 등이다. 실험결과로부터 캐비티 외부로의 용융노심 분사비율은 높은 초기압력과 큰 파열면적을 가진 경우가 더 높으며 캐 비티의 구조가 분사비율에 큰 영향을 미침을 알 수 있었다. 본 연구의 실험결과를 이용하여 분사비율에 대한 실험관계식을 무차원 유효시간의 함수로 도출하여 제시하였으며, 이 실험관계식은 본 실험결과 뿐만 아니라 한국 과학기술원의 실험자료 및 미국 BNL 실험결과와도 잘 일치하였다.

• 한국태양에너지학회 논문집
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• 제32권3호
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• pp.153-161
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• 2012

This study conducted a survey and field investigation on the application of the Public Obligation System for new & renewable energy in public buildings, as well as energy consumption of each building according to their uses. The findings are as follows: (1) Since the introduction of the Public Obligation System (until June 30, 2011), there was average 1.4 new & renewable energy facilities established at 1,433 places. Preference for solar energy facilities was the highest at 57.8%. (2) The revised act sets the obligatory supply percentage of new & renewable energy for each public building: it is 9.0% for a tax office, 4.2% for a dong office, 8.2% for a public health center, and 12.6% for a fire station. All the public buildings except for fire stations failed to meet 10% expected energy consumption, a revised standard. (3) Energy consumption of each public building was 120.6TOE for a tax office, 124.3TOE for a dong office, 166.4TOE for a public health center, and 174.6TOE for a fire station. The energy consumption was comprised of 80% electric power, 18% urban gas, and 1% oil. (4) Electric power consumption per person in the room was high at a dong office, and fuel consumption per person in the room was high at a public health center. In addition, electric power consumption per unit space was high at a public health center, and fuel consumption per unit space was high at a fire station. (5) In all the four public buildings, power load had the highest basic unit percentage at average 55%, being followed by heating load (21.2%), cooling load (15%), and water heating load (7%). A tax office and fire station had 2% load due to cooking facilities.

• 대한기계학회논문집B
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• 제39권1호
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• pp.109-113
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• 2015

과거의 무기체계는 체계의 목적과 비용 등의 문제로 운용환경에 대한 관심이 부족하여 특히 냉방장치가 탑재되지 않은 체계가 많이 개발되었다. 근래 개발되는 무기체계는 고도의 정밀조준 및 고감도 시스템으로 진화함에 따라 무기체계를 효과적으로 제어하기 위하여 운용자의 운용환경도 중요한 요소로 대두되고 있다. 현재의 무기개발자들은 대부분 통합형 환경제어장치를 장착하도록 설계하고 있다. 본 연구에서는 기 개발된 내부 탄통을 가진 대공포 장갑차에서, 포탑이 회전을 하더라도 효율적으로 차가운 냉기를 전달할 수 있게 하기 위해 드럼바스켓 해석 및 시험을 통해 냉방개선 방안을 도출하고 결과를 실제 장비에 적용하였다.

• 생물환경조절학회지
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• 제9권4호
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• pp.212-222
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• 2000

본 연구는 온실 난방시스템의 연소 체임버에 부착된 연소가스 배출연통에 열회수기를 장착하여 배출가스로부터 열을 회수하는 열회수장치의 성능에 대해 실험·분석하였다. 열회수시스템은 LPG 연소 체임버와 두 개의 열회수기로 구성되어있다. 열회수기-A는 배기가스 연통에 직접 연결되어 있으며 열회수기-B는 열회수기-A에 직렬로 연결되어 있다. 회수되는 열량은 가스의 질량흐름율과 두 측점간의 엔탈피 차이로서 산정하였으며 5가지의 송풍전압별로 각 열회수기의 성능을 검토하였다. 각 열회수기의 공기튜브 다발에 공급된 공기와 튜브 다발에 가로질로 통과하는 연소가스간의 열교환, 열회수기 유·출입부간의 압력감소, 열회수기의 총열회수성능 등으로 온실의 연통을 통해 낭비되는 열을 회수하여 연료 절감 효과를 얻을 수 있는 최적의 열회수장치 설계용 기초자료 확보에 본 연구의 목적이 있다.