• 한국대기환경학회지
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• 제19권4호
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• pp.437-449
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• 2003

A multi-functional indoor smog chamber was designed and evaluated to investigate photochemical or water vapor reaction mechanisms of air pollutants. Various smog chamber experiments could be conducted using ambient air or purified air in this smog chamber. The smog chamber consisted of a housing, a Teflon bag, blacklights, injection ports, sampling ports, and utility facilities. The characteristics of light source, the wall losses of air pollutants, and the quality of purified air were experimentally investigated. The maximum NO$_2$ photolysis rate was 1.10 min$^{-1}$ . In a 2.5-m$^3$ Teflon bag, the wall losses of ambient $O_3$, NO, and NO$_2$ were 1.2~2.4$\times$10$^{-3}$ min$^{-1}$ , 0.7~2.0$\times$10$^{-3}$ min$^{-1}$ , and 0.4~2.0$\times$10$^{-3}$ min$^{-1}$ , respectively. The wall loss of ambient particles ranging 0.05 to 0.2 ${\mu}{\textrm}{m}$ was 1.8~5.4$\times$10$^{-3}$ min$^{-1}$ , which was slightly higher than those of ambient gaseous species. The purified air supply system provided high quality of air with NO$_{x}$ < 1 ppb, and total hydrocarbons < 5 ppb.b.

• 한국입자에어로졸학회지
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• 제9권3호
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• pp.149-161
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• 2013

Experiments on photochemical reactions of purified air alone in an indoor smog chamber were carried out after flushing Teflon bags with purified air for many hours in order to check the level of contamination on the chamber wall. Ozone concentrations were linearly increased from <4 ppb up to about 8 ppb with irradiation time for four hours. Outgassing of NOx from the chamber wall was found to be less than 1 ppb. New ultrafine particles were formed and grown up to about 70 nm during the photochemical reactions, and then total number and mass concentrations of particles were increased from <10 particles/$cm^3$ up to about 4,000 particles/$cm^3$ and $1.3{\mu}g/m^3$, respectively. The wall conditions of these Teflon bags flushed with purified air might not severly affect the chamber experimental results for photochemical reactions of polluted urban ambient air. The difference of gaseous species between two chambers was 2.4 ppb of ozone at most, indicating that the wall cleaning performance of two chambers was nearly similar.

• 환경위생공학
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• 제17권3호
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• pp.115-120
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• 2002

This study was performed on a questionnaire survey of 500 people about their awareness for indoor air pollution, and measured efficiency of air cleaner which can remove the CO and air-borne particulate of ETS(Environmental Tobacco Smoke) in air clean chamber. The room-size cleaner for measuring indoor air contaminants has been applied to evaluation of two different air cleaner such as the mechanic air cleaner with hepafilter(HPA) and the electrostatic air cleaner with metal plate. The measuring experiment was carried out in a chamber by sampling the air. The results obtained were as follows; As respondents are having their 90% of daytime indoors a day, and 38% of them can feel indoor air pollutions degrees directly by their sense of smell, For the installation of indoor pollution control equipment, 34% of all respondents installed air cleaner because of the problem of economical charge and almost respondents was not satisfied the trust of ability purified indoor air pollutants. In the experimental results, it was found that more than 95% of CD and air-borne particulate of ETS were removed within 20 minutes. The reaction kinetics of removal pollutants was verified as the pseudo-first order, Finally, it appeared that the room-sire air cleaner can be applied to new technology for removing indoor air contaminants.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.636-643
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• 2001

Bacillus sp. AIR-5, a strain from soil, produced an extracellular maltopentaose-forming amylase from amylose and soluble starch. This bacterium produced 8.9 g/l of maltopentaose from 40 g/l of soluble starch in a batch fermentation and the maltopentaose made up 90 % of the maltooligosaccharides produced (from maltose to maltoheptaose). The culture supernatant was concentrated using a 30 K molecular weight cut-off membrane and purified by DEAE-Cellulose and Sephadex G-150 column chromatographies. The purified protein showed one band on a native-PAGE and its molecular mass was estimated as 250 kDa. The 250-kDa protein was composed of tetramers of a 63-kDa protein. the isoelectric point of the purified protein was pH 6.9, and the optimum temperature for the enzyme activity was $45^{\circ}C$. The enzyme was quickly inactivated above $55^{\circ}C$, and showed a maximum activity at pH 8.5 and over 90% stability between a pH of 6 to 10. The putative N-terminal amino acid sequence of AIR-5 amylase, ATINNGTLMQYFEWYVPNDG, showed a 96% sequence similarity with that of BLA, a general liquefying amylase.

• 에너지공학
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• 제11권4호
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• pp.306-316
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• 2002

본 연구에서는 공기청정기의 최적설계에 필요한 자료를 획득하기 위해 다양한 실내공간에서의 유동에 대한 연구를 수치해석적인 방법으로 수행하였다. 실내유동 해석을 위해서 사용된 공기청정기의 사용처로는 물류창고, 아파트 거실과 주방, 6인 병실을 선정하여 계산을 수행하였다 시간에 따른 평균농도 변화는 모든 실내공간에서 완전 혼합(perfect mixing)인 경우와 매우 흡사하게 나타나는 것을 볼 수 있었고, 공기청정기의 설치 위치가 시간에 따른 실내의 평균농도 변화에 미치는 영향은 미미한 것을 볼 수 있었다. 실내의 국부적인 농도를 살펴보면 사용처 별로 유동의 흐름이 원활하지 못해서 생기는 공기정화 취약구 역을 관찰할 수 있었으며, 이는 각 공간모델과 공기청정기의 설치위치에 따라 크게 달라지는 것을 볼 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제9권5호
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• pp.209-212
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• 2008

We developed a simple and effective purification method to obtain high-purity single-walled carbon nanotubes (SWCNTs) with low surface damage. The purification process consists of oxidization at $430^{\circ}C$ for 1 h in a furnace system of air atmosphere and homogenization in dilute hydrochloric acid solution for extremely short time. The role of homogenizer was examined during purification process in terms of purity and quality of purified SWCNTs. High-purity and low surface damage of SWCNT products was obtained using homogenizer which was operated at 8500 rpm for 10 min in the environment of 7 % HCI solution. From XRD spectra, we observed that metal catalysts were thoroughly removed. Raman spectra showed that the intensity values of crystallization ($I_{G}/I_{D}$) of purified SWCNTs were very similar with that of pristine SWCNTs. Moreover, the structure damage of purified SWCNTs was hard to find from electron microscopy. Consequently, homogenizing, which is a quick and simple manner, can be promising method for obtaining final SWCNTs with clearly high purity and crystallinity.

• 약학회지
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• 제7권1호
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• pp.26-29
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• 1963

Three systems such as CaS, BaS and ZnS are used as ground materials and transition elements such as Bi, Cu, Ag and Ni are used as activators to preared phosphorescent materials of strong after-grow intensity. These three systems in which we have 31 kinds of different composition samples are heated at given temperatures in the electrical furnace and are cooled in the air in order to crystallize them. In the case of BaS system, the mixture of CaO and purified S is better than the other kinds of calcium compound as the ground materials to crystallize phosphors. In BaS system, the mixture of BaCO$_{3}$ and purified S, in ZnS system ZnS respectively is the most proper ground material to prepare such a strong after-grow intensified phosphors. In a given range, the higher in temperature and the longer time of heating, the better phosphors we obtain.

• 환경위생공학
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• 제18권4호
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• pp.64-69
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• 2003

Recently, Indoor air quality(IAQ) in workplace, residential environments and office has been concern of people, scientists and related the public. The oxygen in air was very important and essential element in every aspect of life. This study was performed on a questionnaire survey of 400 people about their awareness of indoor air quality, oxygen generators and measured of oxygen concentration in indoor environment. The results obtained were as follows; As respondents are having their 90% of daytime indoors a day, and 80% of them can feel indoor air pollutions degrees directly by particle matters. The control of most important problems of IAQ was the poor ventilation. We know that 22% of the respondents was recognized the oxgen generator. And for the installation of indoor pollution control equipment, 20% of all respondents installed oxygen generators because almost respondents was not satified the trust of ability purified indoor air pollutants. In the experimental results, it was found that the oxygen concentration of sampling sites were in the range of 20~23.5%. Therefore, it was recommended that the government related IAQ was suggested the guideline and control of oxygen generators. Finally, it appeared that the oxygen generators using indoor environment can be applied to new technology for cleaning of indoor air.

• 한국대기환경학회지
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• 제11권2호
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• pp.185-190
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• 1995

Recently, because of the worse of the air pollution, the excessive airtught of building and the inferiority of air conditioning system, the development of high efficiency air purification technology was enlarged to the environmental improvement of an indoor or a harmful working condition. The air purification technology has used chemical filters or charcoal filters or charcoal to remove hazardouse gaseous pollutants (SO$_{x}$, NO$_{x}$, NH$_{3}$, etc.) by air pollutant control technology, but they have many problems of high pressure loss, short life, wide space possession, and treatment of secondary wastes. For these reason, the object of reasearch shall be hazardous gaseous pollutants removal by the surface discharge induced plasma chemical process that is A.C. discharge of multistreams applied A.C. voltage and frequency between plane induced eletrode and line discharge eletrode of tungsten, platinum or titanium with a high purified alumina sheet having a film-like plane. As a result, the control performance for hazardous gaseous pollutants showed very high efficiency in the normal temperature and pressure. Also, after comtact oxidation decomposition of harmful gaseous pollutants, the remainded ozone concentration was found much lower than that of ACGIH or air pollution criteria in Korea.rea.

• 한국재료학회지
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• 제4권3호
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• pp.312-318
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• 1994

이 논문은 절연유를 정제하여 $SF_6$ 가스를 용해시켰을 때 절연유의 수십 MHz대의 고주파 절연파괴 전압과 유전특성에 관해서 연구한 것이다. 1)절연유에서의 고주파 전류는 전압의 1/2승에 거의 비례하여 증가한다. 2)전원주파수가 증가함에 따라 고주파 절연파괴는 주파수의 제곱에 역비례하여 감소하는 현상을 나타내고 AC절연파괴의 전압때보다 약 35%정도가 감소한다. 3) 용해된 기체의 압력을 증가시킴에 따라 고주파 절연파괴 전압은 원만하게 증하한다. 4)전원주파수의 증가에 따른 유전정접(tan $\delta$)은 거의 지수 함수적으로 증가하고 유전률($\varepsilon$)은 [0.6% MHZ]의 기울기로 삼소하는 경향을 나타낸다. 5) $SF_6$ 가스를 용해시켰을때 절연파괴 특성은 Air 또는 Ar을 용해시켰을 때 보다 약 25% 정도 향상되는 특성을 나타낸다.