• KIEAE Journal
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• 제10권5호
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• pp.87-93
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• 2010

The objective of this study is to verify the safety in case of fire and change of residential environment for different wall construction approaches in a stairways apartment house. In order to confirm that case_1, which is current case that most of wall is opened and the case 2, which upper part of wall is limitedly opened are compared and analyzed based on simulations of fire, escape and natural ventilation performance. The analysis reveals that possible escape time for case 1 was more than 600 seconds and for case 2 was 195 seconds. Since the escape times for both cases were over 128 seconds, it would be reasonable to assume that every resident would escape. The simulation results on natural ventilation performance shows the air change per hour of case 1 and case 2 were .19n/h and .16n/h and there was 1.2 times difference. However, the difference was too insignificant and it could be seen as that different approaches on wall construction would not significantly influence on natural ventilation performance.

• 해양환경안전학회지
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• 제30권2호
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• pp.165-175
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• 2024

수소는 기후변화 위기에 대응하기 위한 에너지원 중 하나로 주목받고 있다. 그러나, 수소는 밀폐된 공간에 누출되면 천장으로 상승하여 축적되고, 점화원과 만나면 화재나 폭발의 위험이 있다. 특히, 수소를 운송하거나 연료로 사용하는 선박은 여러 밀폐된 공간으로 구성되어 있기 때문에 수소를 안전하게 사용하기 위해서는 공간 내에서의 확산 특성을 파악해야 한다. 본 연구는 선박 내 밀폐된 공간에서 수소와 유사한 특성을 가진 헬륨의 누출방향에 따른 확산 특성을 실험적으로 파악하고, CFD 시뮬레이션을 통해 환기횟수가 25, 30, 35, 40, 45ACH로 증가함에 따라 누출방향에 따른 산소농도 변화를 파악하는 것이 목적이다. 연구 결과, 산소농도감소율은 -z 방향의 누출이 2%, +x와 +z 방향의 누출이 1%였으며, 환기소요시간은 -z 방향 누출이 15분 30초, +x 방향 누출이 7분, +z 방향 누출이 9분으로 누출방향에 따라 산소농도와 환기소요시간에 차이가 있음을 보여준다. 또한, 실험공간에서 환기횟수 35ACH 이상부터는 모든 누출 방향에서의 산소농도감소율과 환기소요시간에 유의미한 차이가 없었다. 따라서, 환기횟수를 증가하여도 산소농도와 환기소요시간이 개선되지 않았기 때문에 본 실험환경에서의 적정 환기횟수는 35ACH임을 알 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.736-743
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• 2005

In this study, three different types of mechanical ventilation systems are compared based on their ventilation characteristics: tracer gas concentration decay characteristics, and ventilation effectiveness by calculating actual ventilation air flow rate. The experiments are performed by using a step-down method for measuring tracer gas. $CO_{2}$ gas, concentration in the model chamber. Application of a mixing factor, k, was used and measured values ranged from 0.68 to 0.77. The Type 2 ventilation system was found to have the highest ventilation effectiveness rather than the Types 1 and 3.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.828-835
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• 2017

Airtightness of buildings is one of critical aspects of its energy performance. To build up references of airtightness of wooden houses built in Korea, blower door tests have been carried out in 42 houses since 2006. Causes of air leakage were investigated recently. The average value of air change rate was $3.7h^{-1}$ for light frame house and $5.5h^{-1}$ for post-beam construction at ACH50 (air change per hour at 50 Pa air pressure difference). Foam type insulation was more advantageous in ensuring building airtightness than glass fiber batt. Airtightness of wooden houses which were constructed after 2010 was improved to have less than $1.5h^{-1}$ of ACH50, threshold for application of artificial air change. The average air change rate of CLT (cross laminated timber) houses showed the lowest value, $1.1h^{-1}$, among the tested structures.

• KIEAE Journal
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• 제14권3호
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• pp.87-95
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• 2014

The purpose of this study is to evaluate the correlation coefficients between the airtightness and sound insulation performance of Han-style windows in New Han-ok. To achieve these goals, field measurements were accomplished in 18 bedrooms of 16 Han-oks in which actual residents were living, and then lab measurements were proceeded in the reverberation lab for evaluating the sound insulation performance. Followings are results. The results of the correlation analysis between the airtightness(Air change per hour at 50 Pa, ACH50) and sound insulation performance(Sound reduction index, Rw) in bedrooms of actual Han-oks, it was found that there were no significant correlation between two evaluating values. On the other hand, it was analyzed that the correlation coefficients of total 24 structures(double casement windows, single casement window, casement and sliding windows, single sliding window, 6 types per each structure) were located on 0.6757 exponentially and 0.4154 lineary in the lab evaluating conditions. But, The results of evaluating 4 structure classificatorily, it was found that there were high correlation coefficients(0.8665~0.9273 at ACH50, 0.8414~0.9346 at Rw). These results were signified that the correlation coefficients were changed according to the each structure and case by case analysis were necessary at the same time.

• 한국환경과학회지
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• 제23권2호
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• pp.207-218
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• 2014

A ventilation model was developed for predicting the air change per hour(ACH) in buildings and the airflow rates between zones of a multi-room building. In this model, the important parameters used in the calculation of airflow are wind velocity, wind direction, terrain effect, shielding effect by surrounding buildings, the effect of the window type and insect screening, etc. Also, the resulting set of mass balance equations required for the process of calculation of airflow rates are solved using a Conte-De Boor method. When this model was applied to the building which had been tested by Chandra et al.(1983), the comparison of predicted results by this study with measured results by Chandra et al. indicated that their variations were within -10%~+12%. Also, this model was applied to a building with five zones. As a result, when the wind velocity and direction did not change, terrain characteristics influenced the largest and window types influenced the least on building ventilation among terrain characteristics, local shieldings, and window types. Except for easterly and westerly winds, the ACH increased depending on wind velocity. The wind direction had influence on the airflow rates and directions through openings in building. Thus, this model can be available for predicting the airflow rates within buildings, and the results of this study can be useful for the quantification of airflow that is essential to the research of indoor air quality(temperature, humidity, or contaminant concentration) as well as to the design of building with high energy efficiency.

• 한국태양에너지학회 논문집
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• 제25권4호
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• pp.61-67
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• 2005

The purpose of this study is to evaluate the air tightness of Zero Energy Solar House(ZeSH) and to propose the construction improvement of junctions and penetrations where air infiltration was identified. Air leakage rate were measured by means of blower door test in accordance with ASTM E779-87. The results showed that ZeSH has an excellent airtightness with ACH50/20 (air change per hour at a pressure difference of 50 Pa between inside outside) of 0.34hr-1 and leakage class E by normalized leakage area of ASHRAE.

• 한국환경보건학회지
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• 제27권3호
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• pp.87-98
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• 2001

There has been increased interest in the health effects of the Environmental Tobacco Smoke(ETS) as a confirmed human carcinogen. It has been known to be extremely difficult to make an accurate assessment of exposure to ETS since it is consisted of a variety of components and there are a number of labile chemicals. Therefore, it is necessary to obtain, to interpretate and to provide the data of quantitative exposure assessment to ETS in the field of environmental health. The purpose of this research is to evaluate the concentration of ETS using VOC in indoor office environments. The correlations and concentrations of benzene, RSP, 3-EP, nicotine that are indicators for ETS were investigate with smoking density, air change per hour(ventilation rate). Air samples were taken in smoking room(7 sites), smoking allowed office (3 sites), corridor outside smoking room(7 sites), non-smoking office (9 sites). The concentrations of benzene showed significant difference according to category of indoor office environments. The geometric mean concentration of benzene were 23.56 ${\mu}{\textrm}{m}$/㎥(range 4.80~192.90 ${\mu}{\textrm}{m}$/㎥) in smoking rooms. 6.16 ${\mu}{\textrm}{m}$/㎥ in smoking allowed offices, 1.32 ${\mu}{\textrm}{m}$/㎥ in the non-smoking offices respectively. The ratios of the concentration of benzene between outdoor air and smoking room, smoking allowed office, and non-smoking indicators concentrations, SD, and SI were 0.82(benzene and nicotine). 0.76(benzene and RSP), 0.60(benzene and SD), 0.76(benzene and SI). It is proposed that benzene is a good indicator for ETS.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제20권1호
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• pp.7-14
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• 2014

Purpose: In this study, we performed ventilation simulations for a standard isolation ward including three intensive care rooms, one anteroom(buffer room), and its recommended ventilation equipments. The purpose of this study is to predict outflow of pathogenic bacteria from patient breath to verify the reliability and the safety of the isolation ward. Methods: We suppose three scenarios of the movement of medical staff. The leakage of patient's breath to out of the ward is predicted in these scenarios using CFD simulations. Results: The patient's breath leakage rate to out of the ward in scenario 1 according to room air changes per hour(ACH : 6 and 12) is predicted to be 0.000057% and 0.00002%, respectively. The patient's breath leakage rate to out of the ward in scenario 2 according to room air changes(ACH : 6 and 12) is predicted to be 0.00063% and 0.00019%, respectively. The patient's breath leakage rate to out of the ward in scenario 3, which is the worst case(6 room air changes) is predicted to be 0.1%. Implications: Through the ventilation simulation like that in this study, the reliability and the safety on isolation performance of various plan of isolation ward are predicted quantitatively.

• 해양환경안전학회지
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• 제21권3호
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• pp.303-308
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• 2015

Compressed air has many uses on board ship, ranging from diesel engine starting to the cleaning of machinery during maintenance. In an effort to enhance the performance of the marine compressed air system, this work studied a way to reduce condensation from the air compressor via experiments. Especially more condensation is produced when the temperature at compressor outlets and the humidity of the air are higher. so in the research, drain production change has been observed by additionally installing the cooling fan on the suction portion of the air to air compressor and this is the method for reducing the compressed air drain that has passed through the compressor. For the result, it was verified that when the cooling fan was used, less drain was made where per hour it was 500.9ml of drain and the measured result after installing the cooling fan was that less drain was made. Other additional and various researches are needed including experiments like silica gel passing through the suction portion afterwards.