• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.103-108
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• 2009

Local exhaust system used in toilet and cooking place of low-rise public house installed roof ventilator at terminal of stack. There are many high riser public houses in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser public house depends on stack effect. But Neutral pressure level represents in a terminal of stack with air tightness for the best exhaust efficiency. Thereby, lower floors have the worst indoor air quality. This paper focuses mainly on the exhaust efficiency improved by roof fan with motor installed in high riser public house. It is observed there is higher exhaust efficiency than the existing natural roof ventilator.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.3
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• pp.166-176
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• 1990

Experimental study was made to find the effective ways for cooling of engine room in a power car through natural ventilation, forced ventilation and wind tunnel test of 1:10 model. Through the measurements of inner temperature of engine room and pressure distribution of model surface for the various opening combinations and the fan locations, the following results are obtained. For natural ventilation, side and top opening combination is more effective than the side openings only and optimal opening combination is all side openings with top center opening. For forced ventilation with fan on the roof, the combination of all sides and top opening is more effective than the combination of side and top opening, and the optimal location of fan is top center. When the model is located in the air stream, the combination of side and top opening is more effective than the side openings only, and the optimal location of top opening is the front opening. With both air stream and forced ventilation, the optimal location of fan is the side region, and the direction of side grill installation is found to have negligible effect on the room ventilation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.996-1006
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• 2003

The objective of this study is to find major variables which influence the performance of kitchen and bathroom exhaust systems in high-rise apartment buildings. For this purpose, the influencing factors on the exhaust airflow rates from the kitchen or bathroom are identified and in every cases, which are made of combinations between the influencing factors, the exhaust airflow rates are calculated through the simulations. The results of the simulation show that the exhaust airflow rates from the kitchen and bathroom mainly depends on outdoor air temperature, number of floors, airtightness of the building envelope, fan on ratio, vertically connected to same shaft, exhaust fan capacity for kitchen or bathroom, roof ventilator capacity and shaft area for kitchen or bathroom exhaust.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.418-423
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• 1999

This study was performed to find an efficient method to overcome extremely high temperature within greehhouse in summer season. The actual states of practical use for greenhouse in hot summer season were investigated. About 21.6% of the investigated greenhouse farms were no cultivation, and most greenhouse farms were cultivating under the very inferior environment . To examine thermal enviornment of greenhouse according to cooling or assistant cooling , greenhouses were treated with natural ventilation, shading, roof sprinkling , and evaporative cooling with air cool fan. Shading and operating air col fan showed a drop in temperature of 3.8∼4.2$^{\circ}C$ as compared with natural ventilation, and most greenhouse air temperatures were maintained below 35$^{\circ}C$.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.38 no.9
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• pp.4-9
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• 2009

초고층 공동주택에 설치되는 주방 및 욕실의 배기를 외부로 배출하는 방법은 공용유도관로인 수직덕트를 설치하고 그 상부말단에 하이브리드 루프팬의(hybrid roof fan)이 설치하는 것이다. 하이브리드 루프팬의 기능은 자연통풍력이 약한 하절기는 강제적으로 루프팬에 의해 구동하고 자연배기를 수행할 수 있을 정도로 자연통풍력이 큰 동절기는 루프팬을 운전하지 않는 기능을 보유하도록 유도하는 것이다. 본 고는 이러한 하이브리드 루프팬의 운전조건을 53층 높이의 임의 공동주택에 대해, 수직덕트의 선정한 후, 제시하고자 한다.

• Geomechanics and Engineering
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• v.15 no.6
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• pp.1173-1182
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• 2018

The coal wall, gob-side backfill, and gangues in goaf, constitute the support system for Gob-side entry retaining (GER) in coal mines. Reasonably allocating and utilizing their bearing capacities are key scientific and technical issues for the safety and economic benefits of the GER technology. At first, a mechanical model of GER was established and a governing equation for coordinated bearing of the coal-backfill-gangue support system was derived to reveal the coordinated bearing mechanism. Then, considering the bearing characteristics of the coal wall, gob-side backfill and gangues in goaf, their quantitative design methods were proposed, respectively. Next, taking the No. 2201 haulage roadway serving the No. 7 coal seam in Jiangjiawan Mine, China, as an example, the design calculations showed that the strains of both the coal wall and gob-side backfill were larger than their allowable strains and the rotational angle of the lateral main roof was larger than its allowable rotational angle. Finally, flexible-rigid composite supporting technology and roof cutting technology were designed and used. In situ investigations showed that the deformation and failure of surrounding rocks were well controlled and both the coal wall and gob-side backfill remained stable. Taking the coal wall, gob-side backfill and gangues in goaf as a whole system, this research takes full consideration of their bearing properties and provides a quantitative basis for design of the support system.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.439-448
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• 2019

The bearing capacity of roadside support is the key problem in gob-side entry retaining technology. To study the cooperative bearing characteristics of the roof-roadside support-floor along the gob-side entry retaining, a mechanical model of the composite structure of the roof-roadside support-floor was first established. A method for determining the structural parameters of gob-side entry retaining was then proposed. Based on this model, adaptability analysis of roadside support was carried out. The results showed that the reasonable width of the gob-side entry roadway was inversely proportional to the mining height, and directly proportional to the bearing strength of the roof and floor. And the reasonable width of the "flexible-hard" roadside support was directly proportional to its own strength, and inversely proportional to the width of the gob-side entry retaining. When determining the position and size of the roadside support along the gob-side entry retaining, the surrounding rock environment should be fully considered. Measured results from case study also show the rationality of the model and calculation method.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.480-507
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• 2019

This paper aims at optimizing the auxiliary ventilation system in large-opening limestone mines with unducted fans. An extensive CFD and also site study were carried out for optimization at the blind entries. The fan location, operating mode, and layout are the parameters for optimization. Since the jet stream discharged from the auxiliary fan is flowing faster than 15 m/s in most of the cases, the stream collides with floor, sides or roof and even with the jet stream generated from the other fan placed upstream. Then, it is likely to lose a large portion of its inertial force and then its ventilation efficiency drops considerably. Therefore, the optimal fan installation interval is defined in this study as an interval that maximizes the uninterrupted flowing distance of the jet stream, while the cross-sectional installation location can be optimized to minimize the energy loss due to possible collision with the entry sides. Consequently, the optimization of the fan location will improve ventilation efficiency and subsequently the energy cost. A number of different three-dimensional computational domains representing a full-scale underground space were developed for the CFD study. The velocity profiles and the CO concentrations were studied to design and optimize the auxiliary ventilation system without duct and at the same time mine site experiments were carried out for comparison purposes. The ultimate goal is to optimize the auxiliary ventilation system without tubing to provide a reliable, low-cost and efficient solution to maintain the clean and safe work environment in local large-opening underground limestone mines.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.1
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• pp.15-20
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• 2016

Recently, the u-IT applications for plants and livestock become larger and control of livestock farm environment has been used important in the field of industry. We implemented wireless sensor networks and farm environment automatic control system for applying to the breeding barn environment by calculating the THI index. First, we gathered environmental information like livestock object temperature, heart rate and momentum. And we also collected the farm environment data including temperature, humidity and illuminance for calculating the THI index. Then we provide accurate control action roof open and electric fan in of intelligent farm to keep the best state automatically by using collected data. We believed this technology can improve industrial competitiveness through the u-IT based smart integrated management system introduction for industry aversion and dairy industries labor shortages due to hard work and old ageing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.191-200
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• 2016

The ventilation effect of a ventilation system, which is classified as the forced ventilation and natural ventilation, is predominantly dependent on the combination of air supply and discharge. Perhaps the simplest ventilation is merely supplying the air as it is. However, to improve the indoor working environment during the summer, an air supply that is cooled to some extent has been widely adopted. Recently, a cooling method utilizing the vaporization of water was introduced. In this study, the performance of an evaporation-type air supply unit that was produced by Japan K-company and was installed in a shoe-manufacturing plant in Busan was investigated. The purpose of the experiment was to measure how much the supplied air could be cooled. From this experimental study, we confirmed that the evaporation-type air supply system is efficient, capable of improving the working environment during the summer while minimizing the energy cost.