• Fire Science and Engineering
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• v.19 no.1 s.57
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• pp.70-89
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• 2005

Fire scenarios in a space $20.0m\;\times\;4.0m$ floor and 3.0m high were simulated by using computational fluid dynamics program (FDS 4.0.3) to investigate the effect of the combined operation of both sprinkler and vent systems, which are installed for cooling and blocking smoke which propagates beneath the ceiling of a horizontal corridor, on the temperature and smoke density of it. It was shown that the combined operation both sprinkler and vent systems was more effective than each operation for cooling and blocking smoke, the number of operating sprinklers was two because of corner effect of wall, and over-installed sprinklers deteriorated the effect of cooling and blocking smoke. This study showed that the case of two sprinklers and vent flow rate $3.0m^3/s$ in fire scenario was the most effective for cooling and blocking smoke. It was confirmed that the smoke downdrag occurs in operating sprinkler system, and the more smoke droplets produced by increasing fire size, the greater smoke downdrag occurred.

• The Journal of Sustainable Design and Educational Environment Research
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• v.4 no.4
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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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.3
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• pp.240-246
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• 2006

This paper performed to investigate on vertical temperature distribution, effective draft temperature (ETD) and PMV (Predicted Mean Vote) in the classroom, which is located YangSan city (Kyungsangnam-Do), Korea, is equipped with ceiling unit. The vertical temperature difference between F.L+10 cm (ankle) and F.L+120 cm (neck) of a measuring point which is adjacent corridor in the classroom showed about $1^{\circ}C$ but of measuring point which is adjacent outdoor expressed up to $4^{\circ}C$, The effective draft temperature (ETD) is -2.3 and -0.52 and 0.67 at near ceiling unit but is 1.2 and 3.3 at far from ceiling unit. The PMV of total classroom showed the range of 'Cold' and 'Slightly Cold.' Therefore, to achieve comfort condition in the classroom is equipped with ceiling unit, the location of ceiling unit and discharge angle and discharge distance from ceiling unit are very important elements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.287-293
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• 2008

The purpose of this study was to clarify the effects of air and ceiling temperatures on a type of ceiling cooling system that involves cool water circulation. The experiment is conducted in summer. The subjects (11 young females) are exposed to the following conditions: combinations of air temperatures $(27^{\circ}C,\;29^{\circ}C,\;31^{\circ}C)$ and ceiling temperature of $(22.7^{\circ}C,\;23.7^{\circ}C,\;24.7^{\circ}C)$ in still air and RH 50%. The following results were obtained; the thermal sensation vote is neutral at a mean skin temperature of $34.5^{\circ}C$. The ceiling temperature affected different parts of the body. For example, the forehead, scapula and abdomen produced different skin temperatures. Thermal comfort vote was rated as comfortable at high temperature environment. The satisfaction from the ceiling temperature was valued comfortable zone in this experiment. Mean skin temperature showing higher thermal neutrality temperature than existing studies for floor and wall radiation cooling results.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.626-629
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• 2003

This study is to forecast possible occurrence of internal condensation around parpets and H-beam located at the inside of balcony ceilings on the uppermost floor of super-high apartment buildings faced with open air in order to provide dwellers with more comfortable environment in the related space and get rid of their uneasiness about the condensation. In this study, we estimated internal condensation. which vary in accordance with humidity pressure distribution, at curtain walls, stone panels or lower parts of slabs that constitute outer space of the residence and are weak against heat, through temperature forecast and temperature distribution interpretation program at normal two-dimension temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3672-3679
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• 2015

The heat generated by electrical components during train operation was estimated by measuring the wall temperature in a locomotive, as well as the temperature and speed of the air entering from the outside and then returning to the outside. The temperatures of the electrical components and wall surface in a high-speed train were measured using an infrared camera. The heat generated by the electrical components was exhausted to the outside through a duct installed on the ceiling of the high-speed train. Thus, the temperature and speed of this exhaust air were measured, as well as those of the air entering the locomotive from the outside. The temperatures at the surfaces of the electrical components and walls in the locomotive were also measured using an attachment-type temperature sensor. In addition, the measurement results were applied to analyze how the heat characteristics of the electrical components were affected by the train operation.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.182-187
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• 2002

국내 저온저장고의 주류를 이루고 있는 컨테이너 박스형 저온저장고의 문제점은 재래식 제어방식으로 인한 성능저하 외에도 자체 구조적인 설계상의 문제점을 가지고 있다 이러한 구조적인 문제점을 열거하면 다음과 같다. 첫째, 한 축 방향에 설치되어있는 유니트 쿨러에서 토출되는 냉기에 의해 저장고 내의 공기를 냉각하는 형태이기 때문에 냉기의 분포가 고르지 못하여 균일한 온도 분포를 이루기 어렵다는 단점을 가지고있다. 둘째, 한 축 방향에서 토출되는 냉기가 맞은 편 벽면까지 도달해야 하기 때문에 풍속이 강해야 하며 이로 인해 저장 청과물이 냉해를 쉽게 입고 심한 증산작용에 의해 쉽게 표면건조나 중량감소를 가져온다. 셋째, 천장부와 측벽부가 90$^{\circ}$의 경사각을 가지고 있어 공기의 유동이 원활하지 못하여 에디현상으로 인한 온도나 풍속의 불균일 구간을 피해서 청과물을 저장해야 하기 때문에 그만큼 버려지는 공간이 많아 비경제적이다. 넷째, 위와 같은 문제점들 때문에 중ㆍ대형의 저온저장고를 컨테이너 박스형으로 설비 할 경우 보다 심한 온도 불균일과 냉기유동 분포를 보여 경제적인 손실이 더 커지게 되는 악순환을 낳게된다. 이에 따라 본 연구에서는 국내 저온저장고의 구조적인 설계상의 문제점을 인식하고 이를 해결하고자 3차원 CFD 시뮬레이션을 이용하여 저온저장고의 새로운 모델을 설계하였다. 이론 바탕으로 직접 저온저장고의 시작기를 개발하여 저장고 내부의 역 유동과 난류유통을 해석하였다. (중략)

• Fire Science and Engineering
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• v.15 no.1
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• pp.1-6
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• 2001

In this study, reduced-scale experiments were conducted to understand smoke movements in tunnel fires with the natural ventilation. The 1/20 scale experiments were conducted under the Froude scaling since the smoke movement in tunnels is governed by buoyancy force. Three cases of experiments, in which a natural vent location varied from 1 m, 2 m and 3 m from the fire source symmetrically, were conducted in order to evaluate the effect of the position of ventilation systems on smoke movement. In case of a poo1 whose diameter is 4.36 cm, the temperature of smoke layer passed through the vent was maintained 7~$8^{\circ}c$ less than that of smoke layer without a vent. In case of a pool whose diameter is 5.23 cm, the average velocity passed through the vent was decreased when it was close to the fire source. And the maximum delay time was 3.86s. In CASE 1, the ceiling temperature was decreased by approximately 8$^{\circ}C$ and the vertical temperature was decreased by approximately $7^{\circ}c$. In CASE 2, both ceiling and vertical temperature wert decreased by $3^{\circ}c$ and in CASE 3, they were decreased by $2^{\circ}c$ each. It was confirmed that the thickness of smoke layer was maintained uniformly under the 25% height of tunnel through the visualized smoke flow by a laser sheet and the digital camcoder.

• Korean Journal of Construction Engineering and Management
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• v.4 no.4 s.16
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• pp.155-163
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• 2003

There are a growing number of cases to expand balconies of apartments faced with open air in order to enhance functional satisfaction and efficiency of dwelling space. In case of the balcony expansion at the floor, however, it is difficult to exclude a possibility of bringing about internal condensation due to the difference of temperature between indoor air and outdoor air caused by the Inflow of outer low-temperature air through the upper part of ceilings by failure in completely putting together the outer composite wall panels on the aluminum curtain walls installed at outer walls This study is to forecast possible occurrence of internal condensation around parapets and H-beam located at the inside of balcony ceilings on the uppermost floor of super-high apartment buildings faced with open air in order to provide dwellers with more comfortable environment in the related space and get rid of their uneasiness about the condensation. In this study, we estimated internal condensation, which vary in accordance with humidity pressure distribution, at curtain walls, stone panels or lower parts of slabs that constitute outer space of the residence and are weak against heat, through temperature forecast and temperature distribution interpretation program at normal two-dimension temperature

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.726-733
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• 2016

In this study, a computer simulation of the three types of air distribution systems, open type system, aisle partition system and aisle containment system, to evaluate the applicability of the aisle partition system on a data center server room. The variables of the simulation were the height and location of the partition fixed on the top server rack. The energy efficiency of the air distribution systems were confirmed to be excellent in the order of the aisle containment system, aisle partition system, and open type system. In the cold aisle partition system, the height of the partition that can be effective in saving cooling energy by obstructing sufficient air recirculation was found to be more than 0.9m. In the hot aisle partition system, the height of the partition was found to be more than 0.8m.