• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.155-160
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• 2020

In this study, the pleasant driving environment of the driver and passenger in the summer was investigated through the internal flow analysis of air due to the opening and closing of the car windows. The conditions on the entrance of the air conditioner with the opening and closing status of vehicle window were applied to the flow analysis by taking into consideration the actual driving environment. The automotive air conditioning outlet, the seat and the inside of car were modeled. As the air flow inside the car was analyzed, the air flow configuration and the temperature distribution were examined. In this analysis, the results were taken in consideration of only the effects of internal air and the opening and closing of window, assuming the interior of the vehicle as insulation. The analysis of each condition shows that these models maintain a pleasant environment. It is seen that this analysis result on the internal flow analysis according to the opening and closing of vehicle window can be applied by converging with the field of design.

• Journal of computational fluids engineering
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• v.5 no.3
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• pp.8-15
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• 2000

This research is aimed to find out how the inlet angle of secondary air affects the uniformity of temperature distribution inside a small incinerator. A commercial code, PHOENICS, is used to simulate the thermal-flow field of an incinerator. The computational grid system is constructed by Multi-Block technique provided by PHOENICS. Numerical experiments are done with the five different angles of secondary air inlet. The uniformity of temperature distribution is evaluated by checking the standard deviation of temperature distribution in an incinerator. The computational results show that there is the minimum value of standard deviation at the certain angle of secondary air inlet, which means that there is an optimum angle of secondary air inlet that could improve the uniformity of temperature distribution in an incinerator. The optimum angle of secondary air inlet is between 30 degree and 45 degree in this particular case.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.217-228
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• 2000

Circulating Fluidized Bed Combustor(CFBC) has been used for the incineration of waste sewage sludge and for the power generation. In this study hydrodynamic characteristics of two phase flow have been studied in a riser section of CFBC. A lab-scale riser is designed and SiC (Geldart type B) is used for solid particles. Experiments are performed by controlling the fluidization parameters including superficial velocity and secondary air to primary air ratio for determination of solid holdup profiles in the riser. Superficial velocities of each fluidization regime are well agreed with results predicted by a theoretical model. The results show that the axial solid holdup distributions calculated by measuring differential static pressures in the riser are found to show a basic profile described by a simple exponential function. Our flow regime during experiments mainly belongs to fast fluidization regime for particle size of 300${\mu}m$. As the SA/PA ratio increases, solid holdup in the lower dense region of the riser increases.

• The Korean Journal of Rheology
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• v.8 no.3_4
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• pp.207-214
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• 1996

사출성형은 많은 장점과 유용성에도 불구하고 싱크마크나 휨과 같은 변형문제를 피 하기 어렵다. 이것은 성형품의 부위별 온도분포 및 냉각속도 차이에 의한 잔류응력에 기인 하는 것으로 구조가 복잡하거나 크기가 쿤 경우에 더욱 더 문제가 되기 쉽다. 이와 같은 문 제를 해결하기 위하여 성형품의 내부에 기포를 형성시켜 수지의 수축분을 기포의 성장으로 보상하여 주는 가스사출성형이 개발되어 많이 활용되고 있는 실정이다. 한편 일반 가스성형 과 달리 수지를 완전히 채운후 저압의 공기를 이용하여 기포를 발생시켜 수지의 체적수축분 을 보상해주는 PFP성형기술은 가스사출의 나점인 공기의 유동조절문제를 해결하고 비용이 저렴한 등의 잇점을 가지고 있다. 이 과정은 가스성형공정의 2차 침투과정과 매우 유사하나 아직까지 이에대한 이해나 연구는 매우 부족한 실정이다 본 연구는 기포의 성장이 수지의 체적수축에 의한 것이라는 가정에 근거하여 기포성장길이에 관한 모델링을 수행한 것이다. 실험결과와의 비교를 통하여 기본 가정에 대한 타당성을 검증하고 여러 인자들의 영향을 살 펴보았다. 본 연구는 PFP성형공정에 대한 이해를 증진시켜 금형설계 및 성형조건 설정에 대한 가이드라인을 제시하며 아울러 PFP공정에 대한 보다 체계적인 이해 및 일반가스성형 의 2차 침투과정 등의 관련 현상에 대한 이해 및 연구에 도움이 될것으로 기대된다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.9
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• pp.2924-2932
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• 1996

As the environmental pollution can be greatly reduced and the waste heat can be also recovered through a combustion of municipal solid waste, the incineration begins to be highlighted recently in our country. But it is very difficult to be operated with constant combustion conditions for a long time as the domestic waste is composed of various components, contains a large percentage of water, and has a low heating value. Therefore, the cold flow test and partial hot flow test were conducted in the incinerator by use of injection angles of a secondary air affecting fluid flow as the first action to maintain the optimum combustion conditions. A model to a scale of 1:10 was designed and manufactured through the similarity of model and prototype flows. Velocities and temperatures were measured through the experiment. From the results, fluid flows of secondary air obtained from partial hot flow test correspond almost well with those of main flow obtained from cold flow test. Consequently, injection angles of secondary air are proved to affect main flow decisively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.10
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• pp.835-842
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• 2003

A three dimensional numerical analysis has been conducted for a stoker type incinerator which has the capacity of 1.5 ton/hr. The objective of the present study is to predict the effects of swirl induced by secondary air and to find an optimal operating condition of the incinerator. In this study, combustion characteristics such as distributions of temperature, velocity and concentration of each species have been examined with various injection types of secondary air and with different flow rates of secondary air in the incinerator. It is found that the secondary air injection on the combustion process makes the path of fluid particle longer in the combustor and enhances the mixing between air and combustion gas by arousing a swirl. Therefore, the injection type of secondary air can be an important key in the design process of incinerator.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.381-384
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• 2009

The Air-breathing engine like Sea-Star I is a second propulsive force generator to fly to the target after the booster generating initial propulsive force is separated. The performance of Sea-Star I engine should be verified because the cruise missile controls direction and altitude during flight, so ground engine test is executed before flight test. This these presents evaluation method of ground engine test to verify performance of Sea-Star I's engine.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.31 no.8
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• pp.15-18
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• 2002

축열 공조방식 중 현재 가장 많이 보급되고 있는 방식은 빙축열 방식과 수축열 방식이다. 본래 축열식 공조는 열원 용량을 감소하고, 값싼 심야전력을 통해서 운전비용(running cost)의 절감을 목적으로 하지만, 열을 저장하기 위한 "축열조"가 필요하므로, 필연적으로 초기투자비(intial cost)의 증가를 동반하며, 기존의 건물에는 쉽게 적용할 수 없는 등의 문제점이 있다. 따라서 축열을 위한 초기비용을 증가시키지 않는 축열식 공조방식으로서 건축물 자체가 가지는 높은 열용량에 착안하여 구조체 축열에 관한 연구가 최근 활성화되고 있다. 구조체 축열은 건축물 그 자체를 축열 매체로 이용하기 때문에 별도의 축열조가 필요 없고, 구조체 로부터의 "복사"형태로 거주영역에 직접적으로 작용하여 실내의 온열환경을 향상시킬 수 있다. 이 때문에 2차측 공조기의 용량을 절감시킬 수 있고, 축열 부위에서의 열반송이 필요없는 등, 구조체 축열 시스템은 기존의 빙축열과 수축열 방식에서는 없는 여러가지 장점을 가지고 있다. 구조체 축열 공조시스템은 기존의 공조시스템 중에서 급기구 부위만을 변경하여 주간에서 종래의 공조시스템과 같이 실내로 공조 공기를 급기하고, 야간에는 급기구에 설치된 댐퍼를 조절하여 천정면으로 공조 공기를 급기함으로써 구조체에 열을 축열시키는 방안이다. 본 시스템은 기존의 설비시스템을 이용하여 건축물의 구조체를 축열, 공조개시전 및 주간의 부하를 대폭 줄임으로써 에너지를 절감시킬 수 있다는 장점을 갖는다. 따라서 구조체 축열 공조시스템은 "지구환경 유지.전력부하 평준화.안전성.에너지 절약.비용절감.쾌적성"의 모든 조건을 만족시키는 유력한 차세대 공조 방식이 될 것으로 판단되며, 본 보에서는 공기순환형 구조체 축열시스템을 소개하고자 한다.

• Journal of the Korean Vacuum Society
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• v.13 no.2
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• pp.65-71
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• 2004

ESR spectrum change has been investigated for the PECVD deposited a-C : H films exposed in the atmosphere. Though depending on the deposition conditions, it was observed that generally ESR signal height decreased and linewidth increased as the exposure time increased. The spin density decreased down to 40-80% depending on samples. The decrease of spin density of the a-C : H films in the air was attributed to permeation of moisture into the films and subsequent migration and redistribution of hydrogens. And the ESR signal height increased again and the linewidth decreased when the a-C : H samples were placed again in the vacuum, which was attributed to oxygens extracted from the samples. Consequently, the ESR spectrum change for the a-C : H films exposed in the air was regarded to be associated with the decrease of spin density as well as the permeation of oxygens into films.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.3
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• pp.21-28
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• 2022

Fine dust enters the lungs or blood vessels through the respiratory tract through the air. Recently, due to the fine dust problem, the demand for air purifiers in Korea is also increasing rapidly. Moss is the oldest terrestrial plant, and it is known that it has the property of adsorbing and decomposing heavy metals and fine dust. To compare the effect of reducing fine dust between moss and the existing chemical filter (Hepa), a cube of 1 m³ was manufactured and the amount of fine dust reduction under a controlled environment was compared. Under the fine dust conditions, an umbrella moss filter, rat tail moss filter, feather moss filter, and silk moss filter were inserted for a total of 40 experiments, 10 times each in 4 different situations. The difference between the amount after 30 minutes was statistically significant for all filters. However, as a result of the test, it was confirmed that there was no statistically significant difference between filters for fine dust, mixed gas, CO₂, and O₂. In particular, it was confirmed that the previously claimed effect of oxygen generation was almost nonexistent. Through this result, it was confirmed that the reduction of fine dust is effective regardless of the species view of moss, and it is expected to replace or supplement the chemical filter of the existing air purifier through future improvement.