• Fire Science and Engineering
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• v.25 no.4
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• pp.94-102
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• 2011

Hot smoke test is done in a subway tunnel. Alcohol trays of 1.0 MW and smoke generators are used for generating hot smoke. The fans equipped with the tunnel are successively run 9 min after smoke generation. It is verified how hot smoke is controlled by fans. Velocity and direction of flow, temperature and smoke density are measured and analyzed for smoke control performance of the tunnel with fans and analyzed from the fire-safety-point of view. Velocity of smoke flow is obtained by using measured velocity and temperature at the ceiling of the tunnel. The time when smoke-control flow is builded up is different for the different positions. Velocity distributions at various positions will be used for the boundaries and the comparison data in numerical simulations for evaluation on smoke-control facilities of subway tunnel.

• Journal of the Semiconductor & Display Technology
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• v.10 no.1
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• pp.1-6
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• 2011

In this paper, the air flow induced by the rotating flat disk is numerically investigated in a hope to better understand the air flow structures inside the wax spin coater for a silicon wafer polishing station. Due to the complex inner geometry of actual spin coater such as the casing around the rotating ceramic block and servo motor, recirculation of air flow is inevitably found on the coating target if the internal space of spin coater is closed at the bottom and it could be the possible source of contamination on the wax coating. By numerical flow simulation, we found that it is necessary to install the air vent at the bottom and to apply the sufficient air suction in order to control the path of air flow and to eliminate the air recirculation zone above the spinning surface of coating target.

• Particle and aerosol research
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• v.15 no.1
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• pp.27-36
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• 2019

Numerical analysis has been conducted on three-dimensional airflow distribution in the passenger cabin of a high-speed electric train. The types of air distribution systems investigated in the present study were those of TGV and Shinkansen. The Reynolds-averaged Navier-Stokes equations governing the mass and momentum conservations of the airflow in the cabin were solved by using a finite volume method, which are coupled with the standard $k-{\varepsilon}$ turbulence model equations. Predicted velocity distributions were presented on several selected planes in the passenger cabin. The present three-dimensional simulations were found to show the overall features of the airflow in the passenger cabin fairly well. In particular, it was shown that the type of air distribution for Shinkansen was more suitable for a non-smoking cabin than that for TGV.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.9
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• pp.610-619
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• 2011

This paper investigates the simplified comfort index and control logic for VRF (Variable Refrigerant Flow) system by using 3 environmental factors such as temperature, humidity and air flow. Indoor test under thermal load was conducted to explore relationship of each environment factors that is related to simplified comfort index. Simplified comfort function that has 3 environmental variables was proposed based on survey results. Each factor is measured and comfort preference was surveyed by more than 30 subjects in the indoor comfort test. Moreover, control logic for VRF system was developed and then simulated by using thermal load calculation method and verified with test. The proposed comfort function was in good agreement with survey results, and also verification test trend of comfort change and maintenance are quite similar with survey. Furthermore, through the additional test data analysis some differences of comfort according to position of people staying in the test room were additionally investigated by air flow. People being under an exit of air in the indoor air-conditioner feel more comfortable condition and speed of response to comfort change is relatively fast.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5628-5636
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• 2012

Effective drying method of sewage sludge is researched in this study. To dry the sludge, chain crusher flash dryer was adopted to remove moisture content in the cell which is mostly responsible for the sludge moisture content. And Pilot plant experiment was conducted in real life sewage treatment plant to study effect and characteristics of operating conditions. Operating variables include sludge feeding rate, rotational speed of chain, process temperature and feed moisture content. As rotational speed of chain increased, product yield of sludge increased, and the performance of the testing system increased. And, as process temperature increased, the sludge drying efficiency increased. It is found that optimum feed moisture content is at 60% which shows the maximum sludge product yield and about 10 moisture content(%) of sludge product. Sludge feed rate showed optimal value, and when the sludge feed rate is exceeded, sludge product yield did not increased but the amount of residue increased. Pilot plant experiment results are as follow. The optimal condition for the rotational speed of chain 1600rpm(max. speed), final sludge discharge temperature $80^{\circ}C$, feed moisture content 60%, and feed rate 60kg/h. When the plant was operated at the optimal conditions, the final product showed fairly good results such as sludge product yield 85.5%, moisture content 11.0% and sludge drying efficiency 81.7%.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.213-220
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• 2000

Grafting of fruit-bearing vegetables has been widely used to increase the resistance to soil-borne diseases, to increase the tolerance to low temperature or to soil salinity, to increase the plant vigor, and to extend the duration of economic harvest time. After grafting, it is important to control the environment around grafted seedlings for the robust joining of a scion and rootstock. Usually the shading materials and plastic films are used to keep the high relative humidity and low light intensity in greenhouse or tunnel. It is quite difficult to optimally control the environment for healing and acclimation of grafted seedlings under natural light. So the farmers or growers rely on their experience for the production of grafted seedling with high quality. If artificial light is used as a lighting source for graft-taking of grafted seedlings, the light intensity and photoperiod can be easily controlled. The purpose of this study was to develop a prototype system for the graft-taking enhancement of grafted seedlings using artificial lighting and to investigate the effect of air current speed on the distribution of air temperature and relative humidity in a graft-taking enhancement system. A prototype graft-taking system was consisted by polyurethane panels, air-conditioning unit, system controller and lighting unit. Three band fluorescent lamps (FL20SEX-D/18, Kumho Electric, Inc.) were used as a lighting source. Anemometer (Climomaster 6521, KANOMAX), T-type thermocouples and humidity sensors (CHS-UPS, TDK) were used to measure the air current speed, air temperature and relative humidity in a graft-taking system. In this system, air flow acted as a driving force for the diffusion of heat and water vapor. Air current speed, air temperature and relative humidity controlled by a programmable logic controller (UP750, Yokogawa Electric Co) and an inverter (MOSCON-G3, SAMSUNG) had an even distribution. Distribution of air temperature and relative humidity in a graft-taking enhancement system was fairly affected by air current speed. Air current speed higher than 0.1m/s was required to obtain the even distribution of environmental factors in this system. At low air current speed of 0.1m/s, the evapotranspiration rate of grafted seedlings would be suppressed and thus graft-taking would be enhanced. This system could be used to investigate the effects of air temperature, relative humidity, air current speed and light intensity on the evaportranspiration rate of grafted seedlings.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.917-930
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• 2018

A quantitative risk assessment method for quantitatively evaluating the fire risk in designing a road tunnel disaster prevention facilities has been introduced to evaluate the appropriateness of a disaster prevention facility in a large tunnel through which all vehicle types pass. However, since the quantitative risk assessment method of the developed can be applied only to the large sectional area tunnels (large tunnels), it is necessary to develop a quantitative risk assessment method for road tunnels passing only small cars which has recently been constructed or planned. In this study, fire accidents scenarios and quantitative risk assesment method for small road tunnels through small cars only which is based on the methods for existing road tunnels (large tunnels). And the risk according to the distance between cross passage is evaluated. As a result, in order to satisfy the societal risk assessment criteria, the distance of the appropriate distance between cross passages was estimated to be 200 m, and the effect of the ventilation system of the large port exhaust ventilation system was quantitatively analyzed by comparing the longitudinal ventilation system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.962-969
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• 2013

This study used Computational Fluid Dynamics(CFD) to assess the properties of the air current inflow and the flow velocity distribution in the fume hood. In order to verify the effect of improvement, it was also predicted the characteristics of the flow pattern in case the hood face is structurally improved. The assessment of the capture velocity with the existing fume hood confirmed maximum 23 to 30% difference as compared to the root mean square (RMS). And the hood face showed great difference in flow velocity, with the flow velocity in the upper part is 58 to 68% faster than that in the lower part of the hood. So, as a result of the improvement of the hood designed to maintain a steady exhaust at the hood face (that is, installing a baffle on the inner wall and designing the slot type face), a difference of maximum 7% as compared to RMS appeared while maximum 12% differentiation in flow velocity through sections was predicted, showing mitigation of much of the difference in control velocity as compared to the previous structure.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.95-95
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• 2011

가방지 중에서 고급 브랜드의 핸드백은 근래의 세계적인 경기불황에서도 꾸준한 소비층을 형성하면서 매출 상승을 유도하고 있는데, 기존 40~50대 시니어들을 위한 전통적인 레자 또는 자카드 문양직물의 고유한 디자인 뿐만 아니라 20~30대의 젊은 층을 위한 다양한 칼라의 프린팅 문양 직물도 많이 개발되고 있는 실정이다. 본 연구는 잠재권축사와 고강력PET를 이용하여 이소재 복합 ATY를 제조하고 제직 및 날염을 통해 다양한 프린팅 문양을 발현할 수 있는 가방지용 직물 개발에 관한 것이다. 최근의 캐주얼 및 힙합룩은 물론, 베이직 정장 차림까지 트렌디한 우븐 백이 코디 아이템 1호로 떠오르고 있는데, 가방용 브랜드 중"레스포색"과 "키플링" 등이 급상승 기류를 타며 국내에 빠르게 정착하고 있으며 수입 브랜드인 경전상사의 "롱샴"도 폴딩백으로 인기를 누리고 있다. 핫 이슈인 스포티즘을 떠올리지 않더라도 최근의 변화는 소비자의 니즈를 적극 수용하려는 패션잡화 업체들의 움직임을 대변하고 있으며, 직물형태의 백이 합리적인 가격에서나 가볍고 편리한 실용적인 부분 모두 소비자의 니즈를 채워주기에 충분하고, 트렌드가 부각된 가방일수록 시즌에 따라 스피디하게 구매가 이뤄지고 있다는 장점이 있어서, 최신 트렌드의 디자인과 재료 효과를 극대화한 제품이 다수 선보이고 있다. 본 연구에서는 이러한 다양한 트렌드 디자인의 문양 발현을 위한 직물을 위해 PET Base의 잠재권축사와 PET 고강력사를 사용하였는데, 이때 사용되는 잠재권사는 Effect사로써 온도, Air압 등의 공정요소 제어를 통해 Soft한 touch을 위한 잔루프를 발현하도록 하였으며, PET 고강력사는 Core사로 사용함으로써 잠재권축사의 강도를 보강하여 가방지로써 요구되는 강력을 가질 수 있도록 하였다.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.367-370
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• 2012

본 연구는 하나의 장치 내에서 "싸이클론-관성충돌-여과포 집진"이라는 다단 제진 단계가 동시에 이루어져 입경 분포별로 순차적인 제진이 가능한 멀티 집진기의 처리가스 제어 효율을 극대화시킬 수 있는 기류 흐름을 얻기 위한 최적화 설계 조건을 검토하는 것이다. 우선 1단계 제진 과정인 원심력을 이용하여 조대입자의 유선 이탈을 촉진시킬 수 있는 사이클론 유동을 최적화시키기 위한 집진기 입구 형상 설계 검토를 위해 수치 해석적 연구를 수행하였다. 그 결과, 멀티집진기 입구 형상을 일반적인 설계 방식인 접선 유입식으로만 설계한 것에 비해 선회류를 한번 더 가속화시킬 수 있는 가이드 베인을 추가로 설계한 경우 선회류의 pitch가 짧고 강하게 형성되어 사이클론부에서 조대입자의 유선 이탈을 촉진시키는데 매우 효과적인 것으로 예측되었다. 단, 사이클론부 하단 벤츄리 형상으로 인해 약 4~5 m/s의 강한 하향 흐름이 호퍼 하단까지 형성되고 있어 탈리 분진의 재비산 문제가 발생할 가능성이 크므로 벤츄리 형상 설치 유무에 대한 영향도 추가적으로 연구가 필요할 것으로 판단된다.