• Analytical Science and Technology
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• v.24 no.3
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• pp.200-211
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• 2011

In this study, 13 compounds including four volatile fatty acids (VFA) and nine volatile organic compounds (VOC) were analyzed by cryogenic trapping-thermal desorption technique. In order to evaluate the analytical method for VFA, calibration experiments were performed using five different sorbent materials. When the calibration results are compared between different sorbents, sampling tube filled with Carbopack X showed the highest response factor (RF) for both VFA and VOC. To validate this new analytical method for VFA using cryogenic trapping-thermal desorption technique, this method was compared with alkali absorption method recommended by the odor prevention law of the Korea Ministry of Environment (KMOE). For this purpose, unknown samples were analyzed by two different methods, i.e., cryogenic trapping-thermal desorption (TD) and alkali absorption with solid phase microextraction (SPME). When the results of two different methods were compared, ratios of concentrations determined by the two analytical methods (TD/SPME) was found as 0.46 (valeric acid) ~ 0.71 (isovaleric acid). Therefore, additional study is required to properly establish and find stable analytical conditions for VFA analysis. Furthermore, comparison between two different methods should be made with more reliable calibration approaches.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.250-255
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• 2007

Hydrogen storage properties of $Ti_{0.32}Cr_{0.43-X}V_{0.25}M_X$($0{\leq}X{\leq}0.1$, M=Fe, Mn, Si) have been investigated. With varing of Mn content, the lattice parameter of the alloy was unchanged and similar to that of $Ti_{0.32}Cr_{0.43}V_{0.25}$ alloy. With increase of Fe, Si content, the lattice parameters of the BCC phases decreased. When the Fe content was 8 at%, the desorption plateau pressure increased to several atmospheres without decrease of the effective hydrogen storage capacity of the alloy. When the Mn content was 8 at%, the effective hydrogen storage capacity showed approximately 2.5 wt% without change in the desorption plateau pressure. With increase of Si content, hysteresis increased and hydrogen storage capacity decreased rapidly. A study was also made on how desorption temperature affected the usable hydrogen of the $Ti_{0.32}Cr_{0.35}V_{0.25}Mn_{0.08}$ alloy. The temperature was varied from 293 to 413 K, and the pressure from 5 to 0.002 MPa. The usable hydrogen of the alloy was 2.7 wt% when absorbed and desorbed at 293 K and 373 K., respectively. The heat of hydride formation of the alloy was approximately -35.5 kJ/mol $H_2$.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.209-214
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• 2002

냉방과 습기제거에 제습제를 이용하는 것은 효과적이고, 경제적이며 환경 친화적인 방법이다. 제습제를 사용한 공기조화시스템은 학교, 극장, 슈퍼마켓, 병원과 음식점 등 모든 건물에 신선한 공기를 제공함으로써 실내공기의 품질을 향상시킨다. 수분을 포함하는 다량의 공기를 제습하기 위해서는 제습제와 공기의 접촉을 늘려주어야 하고, 이를 위하여 허니컴 형태의 제습제를 사용하는 것이 바람직하다.(중략)

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.05a
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• pp.155-160
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• 2002

최근 들어서 오존층을 파괴하는 것으로 알려진 CFC와 같은 냉매를 사용하지 않고 허니컴식 제습rotor와 rotor식 현열교환기로 구성된 '흡착식제습냉난방시스템'이 개발되어 실용화 단계에 있다. 제습제를 이용한 냉방시스템은 에너지측면에서 효율적이고, 비용 면에서 경제적이며, 환경친화적이다.(중략)

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.201-209
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• 2001

The change of optical transmittance of $PdH_x$ thin film due to hydrogen concentration change was measured at room temperature. Pd film($312{\AA}$ thick) was made by thermal evaporation on glass substrate. Hydrogen absorption and desorption cycling effect on optical transmittance was measured 4 times in the pressure range between 0 and 640 torr. Ratio of optical transmittance to the change of ln pressure(torr) increases with increasing number of hydrogen A-D cyclings in the ${\beta}$ phase.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.295-301
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• 2013

Long-term global energy-demand growth is expected to increase driven by strong energy-demand growth from developing countries. Fusion power offers the prospect of an almost inexhaustible source of energy for future generations, even though it also presents so far insurmountable scientific and engineering challenges. One of the challenges is safe handling of hydrogen isotopes. Metal hydrides such as depleted uranium hydride or ZrCo hydride are used as a storage medium for hydrogen isotopes reversibly. The metal hydrides bind with hydrogen very strongly. In this paper, we carried out a modeling and simulation work for absorption/desorption of hydrogen by ZrCo in a horizontal annulus cylinder bed. A comprehensive mathematical description of a metal hydride hydrogen storage vessel was developed. This model was calibrated against experimental data obtained from our experimental system containing ZrCo metal hydride. The model was capable of predicting the performance of the bed for not only both the storage and delivery processes but also heat transfer operations. This model should thus be very useful for the design and development of the next generation of metal hydride hydrogen isotope storage systems.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.847-856
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• 2014

Spent resin waste containing a high concentration of $^{14}C$ radionuclide cannot be disposed of directly. A fundamental study on selective $^{14}C$ stripping, especially from the IRN-150 mixed bed resin, was carried out. In single ion-exchange equilibrium isotherm experiments, the ion adsorption capacity of the fresh resin for non-radioactive $HCO_3{^-}$ ion, as the chemical form of $^{14}C$, was evaluated as 11mg-C/g-resin. Adsorption affinity of anions to the resin was derived in order of $NO_3{^-}$ > $HCO_3{^-}{\geq}H_2PO_4{^-}$. Thus the competitive adsorption affinity of $NO_3{^-}$ ion in binary systems appeared far higher than that of $HCO_3{^-}$ or $H_2PO_4{^-}$, and the selective desorption of $HCO_3{^-}$ from the resin was very effective. On one hand, the affinity of $Co^{2+}$ and $Cs^+$ for the resin remained relatively higher than that of other cations in the same stripping solution. Desorption of $Cs^+$ was minimized when the summation of the metal ions in the spent resin and the other cations in solution was near saturation and the pH value was maintained above 4.5. Among the various solutions tested, from the view-point of the simple second waste process, $NH_4H_2PO_4$ solution was preferable for the stripping of $^{14}C$ from the spent resin.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.125-132
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• 2006

Transient kinetics of $NH_3$ adsorption/desorption and of SCR(selective catalytic reduction) of NO with $NH_3$ were studied over vanadium based catalysts, such as $V_2O_5/TiO_2$ and $V_2O_5-WO_3/TiO_2$. In the present catalytic reaction process, NO adsorption is neglected while $NH_3$ is strongly chemisorbed on the catalytic surface. Accordingly, it is ruled out the possibility of a reaction between strongly adsorbed $NH_3$ and NO species in line with the hypothesis of an Eley-Rideal mechanism. The present kinetic model assumes; (1) non-activated $NH_3$ adsorption, (2) Temkin-type $NH_3$ coverage dependence of the desorption energy, (3) non-linear dependence of the SCR reaction rate on the $NH_3$ surface coverage. Thus, the surface heterogeneity for adsorption/desorption of $NH_3$ is taken into account in this model. The present study extends the pure chemical kinetic model based on a powdered-phase catalytic system to the chemico-physical one applicable to a realistic monolith reactor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1151-1158
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• 2013

Knowledge of the moisture sorption properties of a material is essential for optimal material development and analysis of the delamination failure caused by vapor pressure at the interlayer during the manufacturing process of integrated packaging devices. In this paper, both temperature dependent absorption and desorption properties according to temperature and humidity model are parameterized and the effects of water activities and temperature are discussed. The activation energy obtained from the parameterized diffusivity determines the acceleration factor for the equivalency of moisture sorption levels, which enables the effect of moisture diffusivity on the equivalent elapsed testing time required for evaluating the reliable life time to be estimated. The acceleration factor evaluated at the reliability testing standard of the flexible packaging module is exampled.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.344-347
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• 2012

The basic strength of the MgO catalyst was enhanced by impregnating it with KF to synthesize a highly active catalyst for the bio-diesel production. To increase basicity, KF impregnated on synthesized MgO in laboratory. The synthesized catalyst was characterized using $N_2$ adsorption-desorption, X-Ray diffraction, X-Ray fluorescence, and $CO_2$ temperature programmed desorption analyses. Bio-diesel was produced from soybean and methanol and its fatty acid methyl ester content was measured to evaluate the activity of the catalyst. The catalyst impregnated with 30 wt% KF exhibited the highest activity, which was attributed to its abundant intermediate base site.