• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.193-201
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• 2001

Acidic air pollutants were collected to characterize indoor air quality in a residential area in the summer. All indoor and outdoor samples were measured simultaneously using an annular denuder system(ADS) in Seoul. The data set was collected from July 26 to September 11, 1997. The mean indoor/outdoor ratios measured from this study were : 0.34 for $HNO_3$; 0.91 for $HNO_2$; 0.22 for $SO_2$; 1.34 for $NH_3$; 0.78 for $PM_{2.5}(d_p$ <2.5 $mutextrm{m}$); 0.90 for $SO_{4}^{2-}$; 0.68 for $NO_{3}^{-}$ and 0.79 for $NH_{4}^{+}$. Indoor concentrations of $HNO_3$, $SO_2$ and $PM_{2.5}$ were highly correlated with the outdoor concentrations. The relationship between indoor and outdoor air is dependent, to a large extent, on the rate of air exchange between these two environments. A tracer-gas decay technique with sulfur hexafluoride ($SF_{6}$) as a tracer gas was used to estimate the air exchange of a private home in the summer. The average air exchange rate was estimated to be 23.7 hr(sup)-1. The deposition velocities for $SO_{4}^{2-}$, $NO_{3}^{-}$ and $NH_{4}^{+}$ calculated were 0.17, 0.69 abd 0.39 cm/sec, respectively.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.839-844
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• 2014

The gas-phase radical-radical reaction $O(^3P)$ + $C_2H_5$ (ethyl) ${\rightarrow}$ $H(^2S)$ + $CH_3CHO$(acetaldehyde) was investigated by applying a combination of vacuum-ultraviolet laser-induced fluorescence spectroscopy in a crossed beam configuration and ab initio calculations. The two radical reactants $O(^3P)$ and $C_2H_5$ were respectively produced by photolysis of $NO_2$ and supersonic flash pyrolysis of the synthesized precursor azoethane. Doppler profile analysis of the nascent H-atom products in the Lyman-${\alpha}$ region revealed that the average translational energy of the products and the average fraction of the total available energy released as translational energy were $5.01{\pm}0.72kcalmol^{-1}$ and 6.1%, respectively. The empirical data combined with CBS-QB3 level ab initio theory and statistical calculations demonstrated that the title exchange reaction is a major channel and proceeds via an addition-elimination mechanism through the formation of a short-lived, dynamical addition complex on the doublet potential energy surface. On the basis of systematic comparison with several exchange reactions of hydrocarbon radicals, the observed small kinetic energy release can be explained in terms of the loose transition state with a product-like geometry and a small reverse activation barrier along the reaction coordinate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.257-258
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• 2008

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.574-578
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• 1992

고분자 전해질형 연료전지(PEMFC)는 전해질로서 수소이온 교환 특성을 갖는 폴리머를 사용한 연료전지로서 다른 유형의 연료전지에 비하여 에너지 변환 특성이 우수할 뿐만 아니라 전력밀도 특성이 우수한 유형의 연료전지이다. 전해질 폴리머로서는 Perfluorosulfonate 멤브레인이 사용되고 있으며, 전지의 작동 원리는 인산형 연료전지와 동일하다. 본 총설 논문에서는 PEMFC의 작동 원리 및 기능상의 설명은 지양하고 고전력 밀도가 가능한 이유와 지금까지의 개발 역사 및 향후 개발 방향 등에 대해서 설명하고자 한다.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3395-3398
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• 2010

• Journal of Korean Society for Quality Management
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• v.43 no.3
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• pp.359-372
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• 2015

Purpose: Through studying the expert's and non-experts panel responses to the questions regarding the attributes of chemical-biological protection cloth quality in terms of the levels of customer demand and technical factors has been studied. We are applied to a QFD matrix with find out the relationship between the selective removal efficiency of chemical-biological cloth and the guidelines of technical approach. Methods: We fabricated several composite of ion-exchange resins with selectively permeable performance designed to facilities water vapor transport and selective adsorption of the harmful gases. With these materials, we characterized on the selectively permeable performance to identify ion-exchange resin with chemical-biological protective cloth. Results: Results showed that ion exchange materials possessed performance with selectively efficiencies as NH3, SOx, NOx and HCl gas. The selective adsorption amount of ammonia and hydrogen gases were $90-80{\mu}g/g$ with TRILITE SCR-BH sulfonated ion exchange resin. The PP non-woven/ion exchange resin adsorbent materials possessed performance with water vapor permeability were 1,100-1,350 g/m2/day, it's was two times high value compare with activated carbon. With these materials, we characterized selectively removal efficiency to identify new ion-exchange material with chemical-biological protective capability. Conclusion: This study shows that a QFD aids in deciding with of the adsorption parameters to optimized with chemical-biological protection cloth manufacturing.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.374-377
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• 2009

The operating temperature of Proton Exchange Membrane Fuel Cell (PEMFC) usually has to be limited under $100^{\circ}C$ to maintain the proper ionic conductivity. Therefore, the only product from reaction, water, is in the liquid phase. Two-phase flow makes the flow phenomenon in the channel difficult to understand and predict. Water blocking in the PEMFC channel or the pore of Gas Diffusion Layer (GDL), called flooding, is known as the main effect of PEMFC degradation. To analyze two-phase flow, the PEMFC with transparent acrylic plate was used. Two-phase flow patterns were observed by varying the current density. When the PEMFC is mounted horizontally, water in the cathode is mainly transported on the interface between the channel and GDL.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.6-9
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• 2008

The efficiency and life time of the proton exchange membrane (PEM) fuel cell system is critically changed with its humidity which should be maintained properly during dynamic operation. Membrane humidifier is required to regulate proper humidity level for the design point of the PEMFC system. In this study, we presented the performance of the cylindrical membrane humidifier which is operated as water-to-gas. Dry air pressure, liquid water flow temperature, and air flow rate were chosen as the operating parameters. Humidity level is expressed with dew point.

• The Research Journal of the Costume Culture
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• v.8 no.5
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• pp.660-667
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• 2000

Clothing ventilation was investigated using a manikin wearing an impermeable overall under an isothermal condition, in which the ventilation occurred only through the openings. The ventilation volume was estimated by both microenvironment volume and ventilation rate, where, the microenvironment volume was measured by an air subsitution method and the ventilation rate by a trace gas method. Microenvironment volume of the experimental garment was about 21.0 liters. Even though it was certainly affected by the distance from the opening, the ventilation rate was more significantly influenced by the opening area and the shape of air layer in the clothing. The volume of air exchange in the clothing microenvironment was affected greatly by the microenvironment volume and the opening area, and it was different for each part of the body with bigger air exchange volume in the microenvironment of the leg as compared to that of the arm.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1458-1465
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• 2018

We present a constructed setup for polarizing $^{129}Xe$ noble gas. Hyperpolarized $^{129}Xe$ has been obtained via spin exchange with an optically pumped rubidium vapor. Optical pumping is based on polarizing the valence electron of rubidium by the resonant absorption of a circularly polarized laser light. The magnetic field of 30 G was used for obtaining $^{129}Xe$ polarization. The apparatus for detecting polarization is a nuclear magnetic resonance spectrometer. The highest $^{129}Xe$ polarization of 54% has been obtained using 60 W circularly polarized laser light with wavelength of 794.7 nm. The measured longitudinal relaxation time of the hyperpolarized $^{129}Xe$ was 72.3 minutes.