• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.958-964
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• 2001

It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the ADPI(Air Diffusion Performance Index) vs. T/L(Throw/Length) curve listed in conventional guide does not consider the perimetric heating load. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and to propose a selection guide for proper diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI value are obtained numerically with various heat load ratios and air flow rates. The ADPI values by numerical result were compared with existing experimental data to verify the method for evaluation of ADPI proposed in present study. In case of a high side wall diffuser, the ADPI decreased with increases of the flow rate on every heat load ratio of present study except 0.75. Also, the ADPI vs. T/L curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee comport thermal environment when diffusers are installed in perimeter zone.

• 설비공학논문집
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• 제16권12호
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• pp.1204-1211
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• 2004

It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the air diffusion performance index (ADPI) vs. throw/length (T/L) ratio curve listed in conventional guide does not consider the perimetric heating load through the walls. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and propose a selection guide for a proper line diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI values are obtained numerically with various heat load ratios and air flow rates. The velocity and temperature distributions and the ADPI values are analyzed by CFD in case of various heat load ratios and air flow rates. Also, ADPI was calculated by those results. The ADPI values by numerical results are compared with an existing experimental data to verify the method for the evaluation of ADPI proposed in a present study. In case of a line diffuser installed at the high side wall, the ADPI decreases according to the increases of the flow rate on every heat load ratio of the present study except 0.75. The ADPI vs. T/L ratio curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee the comport thermal environment when diffusers are installed in perimeter zone.

• 교육녹색환경연구
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• 제4권4호
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• pp.1-18
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• 2004

Research has been carried out to study thermal environment in a classroom under three kinds of air diffusion temperature and six kinds of air diffusion direction for ceiling type air conditioner. The velocity and temperature distributions of air in the room calculated by 3-dimensional numerical method(PHOENICS), This present study was also conducted to calculate the Air Diffusion Performance Index(ADPI) for cooling conditions and Predicted Percentage of Dissatisfied(PPD) for heating conditions. This analysis shows that the optimum angle of ceiling type air conditioner's diffusion is $15{\sim}30^{\circ}$ for cooling mode and about $15{\sim}45^{\circ}$ for heating mode in these calculating conditions. And also analysis has been carried out to evaluate thermal comfort of vertical and horizontal cross section of classroom.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.590-595
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• 2009

PMV and ADPI were numerically investigated in a large space of various ceiling height with air-conditioning systems of two type. The numerical results showed that it is small that the growth of cooling load according to ceiling height rise in a large space without windows. In case of system air-conditioner of duct type embedded in the ceiling, the air mixing effect in indoor is superior to a case installed 4way cassette type in it. For controling thermal comfort at indoor, a system air-conditioner of duct type embedded in the ceiling is little influenced according to ceiling height rise in a large space considered.

• 설비공학논문집
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• 제29권2호
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• pp.74-81
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• 2017

In this study, the combined-type diffuser developed by the Authors, in a previous study, was applied to a residential space. The performance of a ventilation and thermal environment, created by the use of a combined-type diffuser was compared to the pan-type diffuser widely used in apartment houses. In cooling conditions, because of the relatively high air flow rate of ceiling cassette-type air conditioners, the characteristics of airflow distribution in a room were governed by the air conditioner's airflow. In heating conditions, because of the low air flow rate of the diffuser, the characteristics of airflow distribution were governed by the buoyancy effect created by cold external walls and a hot floor. In terms of the Air Diffusion Performance Index (ADPI), which is a thermal environmental index, the result of a combined-type diffuser was greater than a pan-type diffuser in both of cooling and heating conditions. Consequently, the combined-type diffuser showed equal or superior ventilation and thermal environment performance compared to a pan-type diffuser.

• 한국식품과학회지
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• 제23권5호
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• pp.627-632
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• 1991

본 실험에서는 국산 유아용 조제분유의 열처리 정도를 파악하기 위하여 HMF 함량, lactulose 함량, 유청단백질 변성율 등을 측정하였다. 조제분유의 HMF 함량은 $21.0{\sim}43.9{\mu}mol/l$로 분말상의 경우 각종 영양성분의 함량이 더 강화된 (ii)단계 제품에서 많은 HMF 함량을 보였으나, 액상의 경우 can 포장용 제품에서 더 많았다. 조제분유의 lactulose 함량은 분말상에서 $2.5{\sim}11.4mg/100ml$였고 액상에서 $27.0{\sim}164.8mg/100ml$으로 제품의 형태에 따라 많은 차이가 있었다. ADPI에서 제시한 열처리 등급을 기준으로 분류했을 때 대부분의 조제분유 제품이 medium-heat 등급에 해당되었으며, 조제분유의 유청단백질 열변성율을 측정한 결과, 분말상에서는 $1.1{\sim}69.4%$였고 액상에서는 $37.4{\sim}71.3%$이었다.

• 한국전산유체공학회지
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• 제10권1호
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• pp.87-93
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• 2005

Macao, a city with three sides bounded by water, is hot and humid in weather in more than six months of a year. This uncomfortable weather induces the frequency of operating air-conditioners. Choice of location for installation of air-conditioner in a building will affect the performance of cooling effect and thermal comfort on the occupants, which in turn will affect the indoor air quality (IAQ) of the building. In the paper, investigation of distribution on carbon dioxide, room air temperature and velocity, as well as air diffusion performance index (ADPI) of a single bedroom in Macao is studied by using the computational fluid dynamics (CFD) software FLOVENT 3.2. Simulations of locating the air-conditioner at 4 different walls will be done and comparisons and analyses of the results will be performed to decide a proper location for the air-conditioner for obtaining good thermal comfort.

• 설비공학논문집
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• 제18권2호
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• pp.180-185
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• 2006

This study has been conducted in order to develop a temperature-controlled round pan diffuser with variable-openings. Flow visualization was performed to investigate the airflow patterns according to gap openings. The velocity profiles were measured using an omni-directional anemometer for two cases, i.e. a horizontal and a vertical discharge conditions. Numerical simulation also confirms there is a narrow range of gap openings where a horizontal discharge shifts to a vertical discharge. The air distribution performance index increases abruptly when the air discharge shifts from vertical to horizontal direction.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.970-975
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• 2008

This study considers indoor thermal comfort in an ondol space by supply vent configurations to prevent cold draft in winter. A specially-designed vent cap has been investigated in comparison with a round pan-type vent and a simple opening without a cap. Numerical simulations have been conducted using CFD to analyze thermal comfort indices such as Predicted Mean Vote (PMV) and Effective Draft Temperature (EDT) as well as air distribution index i.e. Air Diffusion Performance Index (ADPI). Results show the new vent cap provides improved thermal comfort conditions especially near ondol heated floor, as the cold outdoor air spreads upwards along the vertical wall before reaching occupant region near floor. This paper includes discussions on the flow and comfort distributions created by the thermal jets from the vents.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.14-22
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• 2008

This study is aimed at suggesting a linear-type diffuser which is excellent in terms of range and elegance like existing diffusers in which amount and direction of wind can be freely controled, out of linear-type diffusers with the highest possibility to be adopted for living space of apartments whose height between floors is not so high and utilizing the linear-type diffuser in design. For the purpose, I examined necessary flow and noise properties of linear-type diffusers. Besides, I evaluated its ventilation capacity for persons in there by applying this in the actual living space. I evaluated features and air blast and found that in time of horizontal and vertical effusion, its T/L ratio is 1-1.5, similar to existing cardioid-type linear diffusers, while in time of slope effusion, it is similar to horizontal effusion in terms of range and it has medium figure in terms of pressure drop and effusion speed, indicating it can provide safe and pleasant indoor environment for persons in there in terms of ventilation.