• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.148-153
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• 2009

This paper considers the age of air in a ventilated space with multiple supply inlets. The local mean age of air at a point from one supply inlet is different from those from the other supply inlets. It is the purpose of the present paper to investigate theoretically the relations between the LMA's from each supply and overall combined LMA whether or not to trace the origins of supply air. Transient concentration distributions are calculated with a step-up injection of tracer gas at each supply inlet, and at both inlets simultaneously. The steady state concentration with a continuous tracer injection at a supply inlet works as a weighting factor for the corresponding LMA in calculating the average overall LMA from multiple inlets.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2004년도 동계학술대회 논문집
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• pp.64-64
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• 2004

• 한국농공학회논문집
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• 제59권6호
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• pp.61-71
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• 2017

The tracer gas method has an advantage that can estimate total and local ventilation rate by tracing air flow. However, the field measurement using tracer gas has disadvantages such as danger, inefficiency, and high cost. Therefore, the aim of this study was to evaluate ventilation rate in pig house by using the thermal distribution data rather than tracer gas. Especially, LMA (Local Mean Age), which is an index based on the age of air theory, was used to evaluate the ventilation rate in pig house. Firstly, the field experiment was conducted to measure micro-climate inside pig house, such as the air temperature, $CO_2$ concentration and wind velocity. And then, LMA was calculated based on the decay of $CO_2$ concentration and air temperature, respectively. This study compared between LMA determined by $CO_2$ concentration and air temperature; the average error and root mean square error were 3.76 s and 5.34 s. From these results, it was determined that thermal distribution data could be used for estimation of LMA. Finally, CFD (Computational fluid dynamic) model was validated using LMA and wind velocity. The mesh size was designed to be 0.1 m based on the grid independence test, and the Standard $k-{\omega}$ model was eventually chosen as the proper turbulence model. The developed CFD model was highly appropriate for evaluating the ventilation rate in pig house.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.263-270
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• 2010

In this study, an air cleaner is considered to improve comfort, safety, and health of automobile passengers. The performance and installation conditions of the air cleaner have been studied to investigate their effects on the air quality in the cabin room using numerical analysis. A five-passenger sedan and a seven-passenger minivan that have comparatively large indoor volume have been considered. The distributions of the local mean age and the volume averaged age of indoor air are calculated according to the variation of the placement and the air flow of the air cleaner. In addition, a decrease of contamination concentration, especially VOCs(volatile organic compounds), by the air cleaner is numerically analyzed with time-accurate unsteady calculation to quantify the effect of the air cleaner on the indoor air quality. As a result, the effective installation and operation conditions of the air cleaner for the automobile cabin room could be suggested.

• 설비공학논문집
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• 제10권5호
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• pp.640-648
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• 1998

A numerical study has been conducted to investigate the effect of inflow supply air temperature and velocity on ventilation effectiveness in an underfloor air conditioning space. A low Reynolds number k-$\varepsilon$ model is implemented to calculate steady state turbulent velocity distributions. A step-down injection method is used to calculate local and room mean ages from transient concentrations based on the concept of the age of air. Results show that there is a significant effect of Archimedes number on ventilation effectiveness especially for cooling conditions. Reynolds number shows relatively minor effect on velocity distribution and ventilation effectiveness especially for isothermal and heating conditions. It can be concluded that underfloor air conditioning system provides good ventilation characteristics for cooling conditions because of temperature stratification in the space.

• 한국가시화정보학회지
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• 제14권1호
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• pp.19-26
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• 2016

Modern people spend much time at indoor space. So, People want to make better indoor air condition. But the facade of building is made of glass to be seen urbanely, the effect of solar radiation makes indoor environment worse. This study designs an open space affected by solar radiation with 4-way cassette air-conditioner. Using numerical simulation, this paper investigates thermal comfort and ventilation performance with discharge angles $30^{\circ}$ and $45^{\circ}$. To study thermal comfort, this paper studies distribution of velocity, temperature and effective draft temperature. Also, this paper introduces concept of air age to study ventilation performance. The flow influenced by solar radiation determines thermal comfort and ventilation performance in room space. This study shows that discharge angle of 45 degree has better thermal comfort and ventilation performance than that of 30 degree.

• 한국보건간호학회지
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• 제16권1호
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• pp.190-200
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• 2002

This study was carried out to investigate and analyze TSP of the PC rooms. The concentration of the total suspended particulate and heavy metals contained in the total suspended particulate of the 15 PC rooms located in one local city were measured. The statistical correlation coefficients between the total suspended particulate and factors of the indoor condition (number of fan or size of pc room, illumination), between the heavy metals and factors of the indoor condition were studied. The results are as follows: 1. The factors of the indoor condition of the 15 PC rooms are as follows. Average illumination was 24 luxes. Average number of computers installed were 37. Average number of the fans was 7. and the size of investigated PC rooms was $139.94m^2$. 2. The mean age of the subjects was 21.8 years old. they $(51.5\%)$ used the 15 pc rooms for fewer than 2 hours per one day. 3. The mean concentration of total suspended particulate (TSP) is lower in the evening ${139.085\;(2.462)\;{\mu}g/m^3}$ than the night ${166.216(2.609){\mu}g/m^3}$. 4. The mean concentration of total suspended particulate was industrial work area) residential area) commercial area. 5. The distribution of heavy metals were indicated as Zn>Cr>Pb>Cd in the indoor air at PC rooms. and the concentration rate of Zn was the highest among heavy metals. but this increase didn't show any relationship with many factors of indoor condition (number of fan or size of pc room, lighting) 6. The concentration of TSP & heavy metals didn't have any relationship between the factors of indoor environment (number of fans, size of pc room, lighting).

• 설비공학논문집
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• 제19권10호
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• pp.695-702
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• 2007

In this paper, the ventilation efficiencies of an underground sewage disposal plant were investigated for ventilating system without fan, ventilating system with eleven cross flow fans and ventilating system with sixteen cross flow fans by numerical method. It has been found that the air change effectiveness of the system without fan was predicted 0.44. It means that an additional ventilating equipment is needed to maintain good indoor air quality. For the ventilating system with sixteen cross flow fans, the air change effectiveness was predicted 0.55. The air change effectiveness of the ventilating system with eleven cross flow fans was predicted 0.51. It is known that the air change effectiveness above 0.5 is enough to eliminate pollutant and bad smell in the indoor. Therefore, it is recommended to select the ventilating system with eleven cross flow fans for the underground sewage disposal plant in an economic point of view.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.452-457
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• 2008

We performed a study on the contaminant transfer in a clean space for the location of product and fan filter unit using computational fluid dynamics analysis. To simplify the real product moving process, three different non-moving cases regrading the locations of product were selected: no product, at the lower side, and at the upper and lower sides. And to investigate the characteristics of the contaminant transfer, the arrangement of fan filter units was varied. Local mean air-age and contaminant distribution were used as evaluation indices. From the results, the contaminant transfer to the product was the most when the products were simultaneously located at the upper and lower sides. And the contaminant was easily exhausted regardless of the location of product when the fan filter units were properly arranged at the top side of the clean space.

• 한국산학기술학회논문지
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• 제15권9호
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• pp.5820-5825
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• 2014

본 연구에서는 급기 가압 제연구역 출입문의 개방력 기준을 실측하여 한국인의 체형에 적합한지 여부를 검증하였다. 개방력 기준의 검증은 기술표준원의 인체표준정보를 근거로 NFSC 501A, NFPA 92A 및 BS-EN 12101-6와 비교하였다. 개방력을 측정할 때 인체의 자세는 일어서서 오른손으로 출입문을 미는 것을 기준으로 하였다. 실측한 값을 분석한 결과 30대 남성 및 여성이 미는 힘의 최대값을 나타냈고, 60대에서 최소값을 나타냈다. 또한 모든 연령에서 미는 힘의 편차가 크게 발생한 것으로 확인되었다. NFSC 501A 와 비교한 결과 남성은 20대, 30대, 50대를 제외한 모든 성별과 연령에서 기준보다 낮은 값을 나타냈다. 또한 NFPA 92A 의 기준과 비교할 때 모든 성별과 연령에서 측정치의 평균이 기준보다 낮다. 그리고 BS-EN 12101-6 의 기준과 비교할 때 남성은 모든 연령에서 기준보다 높았으며, 여성은 모든 연령에서 기준보다 낮은 것으로 측정되었다. 따라서 신체적 조건이 외국인과 다른 한국인의 체형을 고려할 때 현재 적용되고 있는 제연구역 출입문의 개방력의 국내 기준 110 N은 하향 조정할 필요가 있는 것으로 판단된다. 또한 국제 기준을 임의로 사용하는 것도 문제가 있으므로 건축물과 사용자의 특성을 고려한 기준의 적용이 필요하다는 것을 제안하고자 한다.