• 청정기술
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• 제18권4호
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• pp.341-346
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• 2012

연구자들은 용수 및 폐수 내에 함유되어 있는 중금속을 효과적으로 제거하기 위한 많은 공정을 연구하고 있다. 많은 공정들 중에서 특히, 물리, 화학적 공정은 생물학적 공정과 비교해볼 때 대체로 간단하고 높은 중금속 제거효율을 얻을 수 있다. 최근에는 방사능원소에 대한 위험성 때문에 물리, 화학적 방법들에 대한 관심이 다시 급격하게 증가하고 있다. 이 연구에서는 화학적 침전, 이온 교환, 전기투석, 그리고 막 분리 등과 같은 다양한 물리, 화학적 공정들을 소개하고자 한다.

• Bulletin of the Korean Chemical Society
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• 제16권11호
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• pp.1028-1032
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• 1995

The structure and electronic properties of the Si(100) surface is studied using the atom superposition and electron delocalization method. The energy released when the symmetric dimer surface is reconstructed to form the buckled dimer surface with p(2X2) symmetry is calculated to be 0.99 eV per dimer in the case of ideal clean surfaces. This indicates that the surface dimer buckling is intrinsic from the viewpoint of thermodynamics. The relaxation energy, when water is adsorbed on the clean symmetric dimer surface to form the buckled dimer surface, is 2.25 eV per dimer for appropriate coverages. These results show that H2O molecule could induce a reconstruction of the surface structure through adsorption. The buckling of the surface dimer is, therefore, more favorable under the existence of water vapour. This conclusion supports the recently obtained experimental observations by Chander et al.

• 한국입자에어로졸학회지
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• 제5권4호
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• pp.171-178
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• 2009

$PM_{2.5}$ is one of critical air pollutants due to its high absorbability of heavy metallic fumes, PAH and bacillary micro organisms. Such a fine particulate matter is often formed through various nucleation processes including condensation. This study attempts to find the nucleation behaviors of $PM_{2.5}$ arisen from coal power stations using a classical heterogeneous Fletcher's theory. The numerical simulation by C-language could approximate the nucleation process of $PM_{2.5}$ from water vapor, of which approach revealed the required energy for embryo formation and embryo size and nucleation rate. As a result of the calculation, it was found that wetting agents could affect the particle nucleation in vapor condensation. In particular, critical contact angle relates closely with the vapor saturation. Particle condensation could be reduced by lowering the angles. The wetting agents aid to decrease the contact angle and surface tensions, thereby may contribute to save the formation energy.

• 청정기술
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• 제19권4호
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• pp.379-387
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• 2013

본 총설에서는 최근 청정수소생산방법으로 큰 관심을 받고 있는 에탄올 수증기개질반응(ethanol steam reforming reaction)에 대해 소개하고자 한다. 다양한 촉매, 반응온도, 에탄올과 물의 몰비에 따른 에탄올 수증기개질반응의 반응특성 및 반응속도식(reaction rate equation)을 검토해 보고자 한다. 또한, 반응기와 분리기를 동시에 장착한 새로운 개념의 막반응기(membrane reactor)를 소개하며, 막반응기의 사용이 일반적인 충전층반응기(packed-bed reactor)에 비해 에탄올 전환율과 수소 수율에 어떠한 영향을 주는지에 대하여 고찰해 보고자 한다.

• 청정기술
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• 제2권2호
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• pp.165-175
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• 1996

절삭가공 공정에 있어서 절삭유제는 환경영향이 가장 큰 요인들 중의 하나이다. 현재의 기술수준에서 환경영향을 줄이기 위한 공정개선의 방법으로 유제의 환경부하에 대한 평가 및 저부하 유제로의 사용대체가 있다. 본 논문에서는 기존의 절삭성을 바탕으로한 절삭유제의 선택방법과 환경영향을 고려한 선택방법을 비교하여 절삭유제의 선택기준을 제시하고 환경부하의 평가방법으로 AMP 방법을 소개한다. 중절삭이며 저속가공인 드릴링가공을 통하여 절삭성과 환경영향을 함께 고려한 절삭유제의 선택과정을 예시한다. 절삭가공의 물질수지를 고려하여 다섯가지의 환경영향의 평가요소를 선정하고 한국공업규격의 다섯가지의 절삭유제를 비교한다. 비수용성 절삭유제가 성능 뿐만 아니라 환경적인 면에서도 수용성 유제에 비하여 우수한 결과를 보여주었다.

• 한국수소및신에너지학회논문집
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• 제19권1호
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• pp.71-76
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• 2008

CuFeOx/$Al_2O_3$ catalysts are developed for the use in sulfuric acid decomposition which is a subcycle in thermochemical iodine-sulfur cycle to split water into hydrogen and oxygen. Both Cu and Fe components are co-precipitated with Al component to enhance distribution of active components. Developed catalysts are improved in the capability of sulfuric acid decomposition and endurance under highly acidic environment compared to commercial catalysts such as Pt/$Al_2O_3$ and $2CuO{\cdot}Cr_2O_3$. Developed CuFeAlOx catalysts exhibited higher sulfuric acid decomposition ability than $2CuO{\cdot}Cr_2O_3$ and longer endurance trends than Pt/$Al_2O_3$ maintaining comparable performance, respectively.

• Rapid Communication in Photoscience
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• 제2권2호
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• pp.42-45
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• 2013

Natural photosynthesis utilizes solar energy to convert carbon dioxide and water to energy-rich carbohydrates. Substantial use of sunlight to meet world energy demands requires energy storage in useful fuels via chemical bonds because sunlight is intermittent. Artificial photosynthesis research focuses the fundamental natural process to design solar energy conversion systems. Nicotinamide adenine dinucleotide ($NAD^+$) and $NADP^+$ are ubiquitous as electron transporters in biological systems. Enzymatic, chemical, and electrochemical methods have been reported for NADH regeneration. As photochemical systems, visible light-driven catalytic activity of NADH regeneration was carried out using platinum nanoparticles, molecular rhodium and cobalt complexes in the presence of triethanolamine as a sacrificial electron donor. Pt nanoparticles showed photochemical NADH regeneration activity without additional visible light collector molecules, demonstrating that both photoactivating and catalytic activities exist together in Pt nanoparticles. The NADH regeneration of the Pt nanoparticle system was not interfered with the reduction of $O_2$. Molecular cobalt complexes containing dimethylglyoxime ligands also transfer their hydrides to $NAD^+$ with photoactivation of eosin Y in the presence of TEOA. In this photocatalytic reaction, the $NAD^+$ reduction process competed with a proton reduction.

• 한국실내디자인학회논문집
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• 제20권5호
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• pp.178-187
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• 2011

This research suggested the hygienic spatial composition of sell-service restaurants applying HACCP(Hazard Analysis and Critical Control Point System). The circulation of the food, dishes, waste, workers and customers were each fractionated and arranged according to the hygienic sequence of cooking food in kitchen and process for eating food within the customer space. The spaces were separated by the degree of cleanness(clean area, semi-clean area, contaminated area). After that, hygiene facilities to remove contamination and pass facilities intended to control moving were added at the possible points of cross-contamination in oder to prevent the cross-contamination. For hygienic spatial composition of self-service restaurant, the following should be acknowledged: In the kitchen, spaces in which the food is handled after being heated should be located in the clean area. As of the customer space, spaces where dishes are prepared, food and water is received, and the table hall should be located in the clean area. Food circulation should flow from the contaminated area to the clean area. Food, dishes, waste should be moved through pass facilities so that workers do not have to come and go between other areas of cleanness. Also lockers for private clothes and lockers for uniforms should be separated. Hygiene facilities should be easily accessible so that workers can use them whenever they enter their working area. The contaminated area where dirty dishes are dealed with should be separated from the clean area. Waste should be thrown out without crossing cooking areas. As of customer circulation, the hygiene facility for hand washing should be located near the space where dishes for self-service are placed. The customer circulation should lead customers to leave restaurants after giving back the dirty dishes in the contaminated area.

• 청정기술
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• 제7권3호
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• pp.215-223
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• 2001

A present semiconductor cleaning technology is based upon RCA cleaning technology which consumes vast amounts of chemicals and ultra pure water(UPW) and is the high temperature process. Therefore, this technology gives rise to the many environmental issues, and some alternatives such as electrolyzed water(EW) are being studied. In this work, intentionally contaminated Si wafers were cleaned using the electrolyzed water. The electrolyzed water was generated by an electrolysis system which consists of three anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in anode and cathode chambers, respectively. In case of NH4Cl electrolyte, the oxidation-reduction potential and pH for anode water(AW) and cathode water(CW) were measured to be +1050mV and 4.8, and -750mV and 10.0, respectively. AW and CW were deteriorated after electrolyzed, but maintained their characteristics for more than 40 minutes sufficiently enough for cleaning. Their deterioration was correlated with CO2 concentration changes dissolved from air. Contact angles of UPW, AW, and CW on DHF treated Si wafer surfaces were measured to be $65.9^{\circ}$, $66.5^{\circ}$ and $56.8^{\circ}$, respectively, which characterizes clearly the eletrolyzed water. To analyze the amount of metallic impurities on Si wafer surface, ICP-MS was introduced. It was known that AW was effective for Cu removal, while CW was more effective for Fe removal. To analyze the number of particles on Si wafer surfaces, Tencor 6220 were introduced. The particle distributions after various particle removal processes maintained the same pattern. In this work, RCA consumed about $9{\ell}$ chemicals, while EW did only $400m{\ell}$ HCl electrolyte or $600m{\ell}$ NH4Cl electrolyte. It was hence concluded that EW cleaning technology would be very effective for promoting environment, safety, and health(ESH) issues in the next generation semiconductor manufacturing.

• 한국환경농학회지
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• 제13권3호
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• pp.262-270
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• 1994

Endosulfan의 잔류분석(殘留分析)을 위한 RIA(radioimmuno assay)는 endosulfan alcohol(EA)-BSA conjugate를 항원(抗原)으로 하여 집토끼에서 면역항체(免疫抗體)를 생산(生産)하였다. 생산(生産)된 면역항체(免疫抗體)의 역가(力價)는 1 : 32,000 으로 endosulfan과 EA 이외(以外)의 유사화합물(類似化合物)에서는 거의 반응성(反應性)을 나타내지 않았으며 RIA를 위한 최적(最適) 희석배수(稀釋倍數)는 1 : 2,000 으로 나타났다. RIA의 최적(最適) 배양온도(培養溫度)는 $4\;^{\circ}C$ 이었으며 endosulfan의 검출범위(檢出範圍)는 $1\;ng-20\;{\mu}g$ 이었고 최소검출량(最小檢出量)은 1 ng 이었다. RIA 기법(技法)을 이용(利用)하여 잉어의 각(各) 조직(組織)과 공시수(供試水)에서 실시한 회수율(回收率) 시험(試驗) 결과(結果)는 GLC/ECD나 ELISA를 이용(利用)한 회수율(回收率)보다 우수하게 나타났다. 시료(試料)에서 RIA에 의한 endosulfan의 검출한계(檢出限界)는 0.1 ppb 였다.