• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.25-30
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• 2003

In the case of a vibration sensitive equipment, it require a vibration free environment to provide its proper function. Especially, lithography and inspection device, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved Giga Class semi conductor wafers. This high technology equipments require very strict environmental vibration criteria in proportion to the accuracy of the manufacturing. In this paper, the dynamic analysis and modal test were performed to evaluate the dynamic properties of the constructing clean room structure. Based on these results, a structural dynamic modification(SDM) were required to satisfiy the vibration allowable limit for pression machine. Therefore, in order to improve the dynamic stiffness of clean room structure, the VSD system which can control the force applied on structure, were adopted and its utility were proved from dynamic test results of the improved structure after a modification work.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.1
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• pp.21-25
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• 2002

To maximize and sustain the productivity of Monascus pigments, various environmental and nutritional parameters, such as the initial moisture content, pH, inoculum size, sample size, and nutrient supplement, that influence pigment production were evaluated in solid-state cultures as follows: initial moisture content, $50\%;$ pH, 6.0; inoculum size $1\;\times\;10^4$ spore cells $(grams\;of\;dry\;solid\;substrate)^{-1};$ sample size, 300 g. All supplementary nutrients (carbon, nitrogen, and mineral sources) added has inhibitory effects on the cell growth and red pigment production. In open tray culture the maximum biomass yield and specific productivity of red pigments were 223 mg DCW $(grams\;of\;initial\;dry\;substrate)^{-1}$ and, $47.6\;OD_{500}\;(DCW\;grams)^{-1}h^h{-1}$ respectively.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.442-447
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• 2006

In semiconductor manufacturing clean rooms, it becomes important to remove airborne molecular contaminants as well as particulate contaminant in outdoor air introduced into clean rooms. One suitable control technique for these chemical contaminants is air washing by water in an outdoor air handling unit. In order to enhance the removal efficiency of chemical contaminants the effect of adding a heating and humidifying process before an air washer was examined.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.468-472
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• 2017

2차원 InSe 단일층에 존재할 수 있는 vacancy defect인 In vacancy, Se vacancy의 원자구조 및 전자구조 특성을 제일원리계산을 이용해 살펴보았다. InSe $5{\times}5$ supercell을 이용하였으며 total energy를 구해 어떤 구조가 가장 안정한지 찾았다. Relax된 결함구조들을 clean InSe와 비교하여 어떤 변화가 있었는지 특징을 분석하였다. 이러한 intrinsic 결함들이 각각 어떤 구조로 relaxation되는지 살펴보고 clean InSe와 비교해보았다. 또한 각 결함구조의 density of states (DOS), projected density of states (PDOS)와 band structure를 clean InSe와 비교해봄으로써 defect state가 어떻게 나타나는지를 찾아보았다.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.144-149
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• 2022

A cryogenic Mixed Refrigerant Joule-Thomson refrigeration cycle was designed to be applied to the semiconductor etching process with non-flammable constituents. 3-stage cascade refrigerator, single mixed refrigerant Joule-Thomson refrigerator, and 2-stage cascade type mixed refrigerant Joule-Thomson refrigerator are analyzed to figure out the coefficient of performance. Non-flammable mixture of argon(Ar), tetrafluoromethane(R14), trifluoromethane (R23) and octafluoropropane(R218) were utilized to analyze the refrigeration cycle efficiency. The designed refrigeration cycle was adapted to cool down the coolant of HFE7200(Ethoxy-nonafluorobutane, C₄F₉OC₂H₅) with certain constraints. Maximum coefficient of performance of the refrigeration system is obtained as 0.289 for the cooling temperature lower than -100℃. The detailed result of the coefficient of performance according to the mixture composition is discussed in this study.

• Air Cleaning Technology
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• v.4 no.2 s.14
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• pp.12-28
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• 1991

• Clean Technology
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• v.10 no.1
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• pp.27-35
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• 2004

Domestic leather company is working hard to solve present environmental problem. Leather industry is realized by representative pollution industry. An advanced nation is trying to develop clean technology by collaborating research institute with the chemical company, and tannery. This research introduced information that is gained through technical transfer in leather processing. This project started to solve environmental problem of leather industry. Specially the environment and economic problem is caused from chrome which exists in the waste water or solid waste. Representative technologies, reduced chrome tanning, non-chrome tanning method, are being introduced through transfer. Also lightweight leather development advances the research which uses non-metal tanning agent.

• Journal of Hydrogen and New Energy
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• v.28 no.4
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• pp.323-330
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• 2017

Ash remaining after coal combustion was used as a catalyst support for tar steam reforming with various proportions of $Al_2O_3$ added for higher reforming efficiency. At a constant Ni content of 12 wt%, a coal ash and $Al_2O_3$ were mixed at a ratio of 5:5, 7:3, 9:1. As a result, the catalytic activity for toluene steam reforming was improved by adding $Al_2O_3$ at $500-600^{\circ}C$. The catalysts with ratio 7:3 and 5:5 reached toluene conversion of 100% above $700^{\circ}C$. When comparing the catalysts in which the coal ash and $Al_2O_3$ mixed at a ratio of 5:5 and 7:3 with the Ni/Al catalyst, it was concluded that this coal ash catalyst has efficient catalytic performance.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.73-81
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• 2000

The removal of ferrous iron (Fe(II)) in groundwater is generally achieved by simple aeration or the addition of oxidizing agent. Aeration followed by solid-liquid separation is the most commonly used as physico-chemical treatment method for iron removal. In general aeration has been shown to be very efficient in insolubilizing ferrous iron at the pH level greater than 6.5. In this study pH was maintained over 6.5 using limestone granules under constant aeration to oxidize ferrous iron. In batch experiments, oxidation rate of ferrous iron was investigated under different conditions including limestone granule size. initial concentration of the ferrous iron, pH, temperature and ionic strength in groundwater. The pH in groundwater was presumed as the most important factor determining oxidation rate of ferrous iron. According as the size of the limestone granules decreased, the pH of the iron contaminated water increased quickly and oxidation of the ferrous iron was achieved immediately too. The oxidation rate of the ferrous iron was found to be proportion to initial concentration of the iron contaminated water, temperature and ionic strength, respectively.

• Clean Technology
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• v.20 no.3
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• pp.218-225
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• 2014

Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. In this work, the gasification behavior of ash-free coal (AFC) was compared with that of the parent raw coal. In order to modify the gasification conditions, the raw coal gasified with fixed variables (water supply, space velocity, temperature, catalysts) in a fixed bed reactor. When catalysts are added by physical mixing method with coal, $K_2CO_3$ was the most effective additives for steam gasification of coal. However, the activity of ash-free coal (AFC) was much less reactive than raw coal due to high temperature extraction in a 1-methylnaphthalene under 30bar at $370^{\circ}C$ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of $K_2CO_3$ in AFC achieved higher conversion rate at low temperature ($700^{\circ}C$). At that time, the molar ratio of gases ($H_2/CO$ and $CO_2/CO$) was increased because of water-gas shift reaction (WGSR) by addition of catalysts. This shows that catalytic steam gasification of AFCs is achievable for economic improvement of gasification process at mild temperature.