• The Korea Beekeeping Bulletin
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• s.338
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• pp.23-31
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• 2008

양봉관리 방법이 양봉 농가마다 조금씩 차이가 난다. 그것은 봉장이 다르고 또한 토질과 기후도 다르가. 그리고 환경 조건도 다르며 따라서 양봉가의 성격과 양봉의 상태도 강군과 약군으로 달라지기 때문에 관리방법도 다르기 마련이다. 1월 양봉관리는 작년을 결산하고 새해는 더욱더 알찬 계획을 세워 풍성하게 수확을 할 수 있는 준비 하는 달이다. 1월의 봉군 관리는 봉군의 상태와 환기에 중점을 두어야 한다.

• Environmental engineer
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• s.60
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• pp.4-7
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• 1991

쾌적한 실내환경은 건물구조, 건물구조의 설계, 건물의 지리적 위치, 건물관리의 기술, 거주자들의 활동상황 및 건물내에서의 환경조건 등에 의해 좌우된다. 따라서 빌딩증후군을 예방하기 위하여는 환기시설의 강화, 실내공기오염원의 제거, 빌딩의 공기공조설비에 대한 검사강화, 실내공기오염을 담당한 행정기관의 부설, 실내공기 질의 중요성에 대한 환경교육의 필요성 등이 요청된다.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.41-41
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• 2006

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.28-28
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• 2006

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.56-57
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• 2011

• Proceedings of the SAREK Conference
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• 2005.06a
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• pp.100-100
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• 2005

• Journal of Energy Engineering
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• v.17 no.2
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• pp.116-123
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• 2008

In order to study the heat transfer, effectiveness and pressure drop of an internal heat exchanger (IHX) for $CO_2$, heat pump under heating condition, the experiment and numerical analysis were performed. Four kinds of IHXs were used. The section-by-section method and Hardy-Cross method were used for the numerical analysis. The effects of IHX on the flow rate of refrigerant, the IHX length, the operating condition of a gas-cooler and an evaporator and the type of IHXs were investigated. With increasing the flow rate, the heat transfer rate increased about 25%. The heat transfer of the micro-channel tube was larger about 100% than that of the coaxial tube. With increasing the IHX length, the heat transfer rate decreased. The low-side pressure drop was larger compared with that of the high-side. And the pressure drop of the microchannel tube was larger about 100% than that of the coaxial tube. With increasing the high-side temperature and decreasing the low-side temperature, the heat transfer rate increased about 3%. From this study, we can see that new correlation on $CO_2$ heat transfer characteristics and tube type is necessary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.15-20
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• 2017

Currently, residential air conditioners operate as a heat pump during winter. In this case, the outdoor heat exchanger acts as an evaporator obtaining heat from cold air. On the other hand, it acts as a condenser during summer transferring heat to hot air. The outdoor temperature changes significantly from high to low. Generally, the air-side j and f factors are obtained at a standard outdoor temperature. Therefore, the applicability of the j and f factors under different outdoor conditions needs to be checked. In this study, tests were conducted for a two-row louver finned heat exchanger changing the outdoor temperature to subzero. The effects of the tube-side brine flow rate were also checked. The results showed that air-side j and f factors were essentially constant and independent of the outdoor temperature, suggesting that an extension of j and f factors obtained under standard conditions to a low outdoor temperature is acceptable. All j and f factors agreed within 9% and 3%, respectively. Tests were also conducted by changing the coolant flow rate. Both the j and f factors did not change according to the flow rate, suggesting that the tube-side heat transfer correlation is acceptable.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.476-482
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• 2006

An experimental study has been performed to investigate the characteristics of air-side heat transfer and friction of a fined tube heat exchanger under heating conditions. Air enthalpy calorimeter was used to obtain the performance evaluation and analysis of the fined tube heat exchanger. Eight finned tube heat exchangers with slit fin, louver fin, and plain fin were used. The air-side heat transfer coefficient was calculated by the log-mean-temperature-difference. Air-side heat transfer and friction were presented in terms of j factor and friction factor on Reynolds number. From the experimental result, it was found that the variations of air-side heat transfer and friction of fined tube heat exchanger with the change of the fin configuration, row number, fin pitch, and tube circuit were obtained. j factor and friction factor decreased with Reynolds number increased. The tube circuit affected the air-side heat transfer and friction. In the case of slit and louver fin, j factor of 1st row was higher than that of 2nd row. But, with increasing Re, j factor was reversed. The characteristics of j factor and friction factor of 2nd row heat exchanger were different according to the kind of fins.

• Journal of Life Science
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• v.19 no.12
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• pp.1829-1835
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• 2009

Hyperventilation (HV) is routinely induced in order to activate brain waves during an electroencephalogram (EEG). The aim of this study was to examine the effects of HV conditions on EEG and suggested basic data for the standardized procedure. Three degrees of HV were induced for 5 minutes with a ventilation volume of 160 ml/min (control group), 240 ml/min, and 300 ml/min in rats. Powers of delta, theta, alpha, and beta waves were examined by a quantitative EEG. The results showed that there was no significant difference in the powers of all EEG waves between the control and 240 ml/min groups. However, a notable change in EEG powers during HV induced by a ventilation volume of 300 ml/min was observed in the frontal cerebral region as follows: power of the delta was increased by 12.8% (p<0.01), powers of the theta, alpha and beta were decreased by 41.3% (p<0.01), 48.6% (p<0.05), and 41.9% (p<0.05), respectively. Therefore, it is concluded that an increase of about 90% of the normal ventilation volume might be adequate for the hyperventilation, and a useful parameter for evaluation of the qualified hyperventilation might be an alteration of the frontal EEG powers.