• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.87.1-87.1
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• 2017

High functional catalyst to efficiently produce clean and earth-abundant renewable fuels plays a key role in securing energy sustainability and environmental protection of our society. Hydrogen has been considered as one of the most promising energy carrier as represented by focused research works on developing catalysts for the hydrogen evolution reaction (HER) from the water hydrolysis over the last several decades. So far, however, the major catalysts are expensive transition metals. Here using first principles density functional theory (DFT) calculations we screen various pyrites for HER by identifying fundamental descriptor governing the catalytic activity. We enable to capture a strong linearity between experimentally measured exchange current density in HER and calculated adsorption energy of hydrogen atom in the pyrites. The correlation implies that there is an underlying design principle tuning the catalytic activity of HER.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.212-216
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• 2021

We investigated the feasibility of hydrogen storage with electrochemically formed VO₂ nanotubes. The VO₂ nanotubes were fabricated through the anodization of vanadium metal in fluoride ion-containing organic electrolyte followed by an annealing process in an Ar-saturated atmosphere at 673 K for 3 h at a heating rate of 3 K /min. During anodization, the current density significantly increased up to 7.93 mA/cm² for approximately 500 s owing to heat generation, which led to a fast-electrochemical etching reaction of the outermost part of the nanotubes. By controlling the anodization temperature, highly ordered VO₂ nanotubes were grown on the metal substrate without using any binders or adhesives. Furthermore, we demonstrated the hydrogen sorption properties of the anodic VO₂ nanotubes.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.3
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• pp.577-585
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• 2001

Dyeing properties of the colorants extracted from pomegranate hull on cotton fabric were investigated. Effects of dyeing conditions and mordanting on dye uptake, color change and colorfastness were explored. Cationic agent treatment was done for cotton to improve low dyeability in natural dyeing. In addition antimicrobial activity of the cotton fabrics dyed with pomegranate colorants was examined by the shake flask method. Pomegranate colorants showed low affinity to cotton fiber and its adsorption isotherm was Freundlich type. Therefore, hydrogen bonding was involved in the adsorption of pomegranate colorants onto cotton fiber. Mordants did not significantly increase dye adsorption. Pomegranate colorants produced mainly yellow color on cotton fabric. In order to improve dye uptake, cotton was cationized by treating with Cationon UK(quarterly ammonium salt) and chitosan. The cationized cotton with Cationon UK showed higher dye uptake and shorter dyeing time, compared with the untreated cotton. Chitosan treated cotton also showed high dye uptake, but chitosan was less effective compared with Cationon UK. Fastness to washing, perspiration, and rubbing was not improved by mordanting and cationizing treatment, but light fastness was increased by all mordants and cationic agent. As dye concentration increased, bacterial reduction rate was increased and mordants did not significantly increase bacterial reduction rate.

• Analytical Science and Technology
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• v.11 no.3
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• pp.174-178
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• 1998

A chelating resin was prepared by the reaction of formaldehyde and resorcinol. It possesses high adsorption selectivity for transition metal ions such as Pb(II) and Ni(II). The adsorption and desorption yields of Pb(II), Ni(II), Co(II), Fe(II) and Zn(II) were determined using batch method. The significant characteristics of the chelating resin is the exchange processes between its hydrogen and metal ions. The mechanism of metal adsorption and desorption seems to be the competing protonation and complexation reaction of the functional group of the resin. This resin was applied to the rapid concentration of trace amounts of these metal ions and to the separation of Pb(II) from other metal ions in bulk solution.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.249-258
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• 2005

A two-column six-step pressure swing adsorption(PSA) process was to study separation of hydrogen from hydrogen and methane($60_{vol}%/40_{vol}%$) binary system onto activated carbon adsorbent. The effects of the feed gas pressure, the feed flowrate and the P/F(purge to feed) ratio on the process performance were evaluated. The cyclic steady-states of PSA process were reached to after 15 cycles. $H_2$ purity increases according as the P/F ratio and pressure increase and the feed flow rate decreases; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 22 LPM feed flowrate, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75% recovery and 99% purity hydrogen. In this study was non-isothermal and non-adiabatic model considering linear driving force(LDF) model and Langmuir-Freundlich adsorption isotherm considered to compare between prediction and experimental data.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.109-114
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• 2000

The relation between the phase-shift profile fur the intermediate frequencies and the Langmuir adsorption isotherm at the poly-Ir/0.1 M $H_2SO_4$ aqueous electrolyte interface has been studied using ac impedance measurements, i.e., the phase-shift methods. The simplified interfacial equivalent circuit consists of the serial connection of the electrolyte resistance $(R_s)$, the faradaic resistance $(R_F)$, and the equivalent circuit element $(C_P)$ of the adsorption pseudoca-pacitance $(C_\phi)$. The comparison of the change rates of the $\Delta(-\phi)/{\Delta}E\;and\;\Delta{\theta}/{\Delta}E$ are represented. The delayed phase shift $(\phi)$ depends on both the cathode potential (E) and frequency (f), and is given by $\phi=tan^{-1}[1/2{\pi}f(R_s+R_F)C_P]$. The phase-shift profile $(-\phi\;vs.\;E)$ for the intermediate frequency (ca. 1 Hz) can be used as an experimental method to determine the Langmuir adsorption isotherm $(\theta\;vs.\;E)$. The equilibrium constant (K) for H adsorption and the standard free energy $({\Delta}G_{ads})$ of H adsorption at the poly-Ir/0.1 M $H_2SO_4$ electrolyte interface are $2.0\times10^{-4}$ and 21.1kJ/mol, respectively. The H adsorption is attributed to the over-potentially deposited hydrogen (OPD H).

• Applied Biological Chemistry
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• v.2
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• pp.45-52
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• 1961

The decomposition of malathion in dust for mulations prepared from four Korean tales as carriers during storage period has been studied. Amberlite CG-120, a cation exchange resin . which has higher cation exchange capacity than tales, was also used as a carrier in hope of finding out the effect of nagative charge upon the decomposition of malathion. Besides the original talc powders obtained directly from the mines, the hydrogen ion saturated forms were also used as carriers for comparisonal study. The saturated ions for the resin were hydrogen, sodium and magnesium. As the physical properties of the tales, colloid content, water adsorption capacity, PH, specific surface, phosphate fixing capacity and exchangeable canons were determined, and these properties were correlated with the amount of the decomposition. Following results were obtained from the experiment. 1. The malathion in the talc in dust was found to decompose around 10-15% ofthe total withina month. About 50% of the decom position that took place after a month was found to occur within a week. 2. The resin which has higher cation exchange capacity than the tales was highly effective in the decomposition of malathion compared with the tales. 3. In every case the saturation of the exchange complexes with hydrogen ion greatly accelerated the decomposition of malathion. 4. The most highly correlated physical properties with the decomposition were colloid content and specific surface of the tales. 5. The water adsorption and phosphate fixing capacities of the tales were found not to correlate with the amount of malathion decomposed. From the experimental results it was concluded that the active negative spots on the colloidal tales or the resin attract the electropositive phosphorus atom in a malathion molecule thereby inducing the decomposition easier. The presence of hydrogen ion nearby might cause a catalytic effect in the decomposition of malathion.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.728-739
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• 2005

An experiment and simulation were performed for hydrogen separation of mixtures by PSA (pressure swing adsorption) process on activated carbon. The binary ($H_2/Ar$; 80％/ 20％) and ternary ($H_2/Ar/CH_4$; 60％/ 20％/ 20％) mixtures were used to study the effects of feed composition. The cyclic performances such as purity, recovery, and productivity of 2bed-6step PSA process were experimentally and theoretically compared under non-isothermal and non-adiabatic conditions. The develped process produced the hydrogen with 99％ purity and 75％ recovery from both processes. Therefore, optimal separation condition was referred multicomponent gas mixtures.

• Analytical Science and Technology
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• v.16 no.3
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• pp.218-225
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• 2003

Hydrogen Chloride is among the most problematic gases used in semiconductor process. It raises serious environmental and health problems due to its extreme toxicity. This study is to develop a method to effectively remove hydrogen chloride gas during the process by using various types of inorganic gas adsorption agents, which have not been attempted in the conventional methods. The removal efficiency of the gas was both qualitatively and quantitatively measured by a FT-IR spectrophotometer. The whole device for the measurement has been designed and built in our lab. The removal efficiencies of hydrogen chloride gas were compared between those tested resins; zeolite A, modified AgA zeolite, ZnO, and $AgMnO_3$. The experimental result revealed that ZnO showed the best efficiency that had removed 0.067 g of HCl per 1 g of the resin used.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.384-387
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• 2006

수소 스테이션에서 사용할 수 있는 Compact 형 수소 PSA를 연구하였다. 기존의 수소 PSA 가 수소 스테이션에서 공간적 제약이 있기 때문에 그 부피를 줄이면서, 또한 효율을 높이기 위해 Compact형 수소 PSA를 고안하였다. Compact형 수소 PSA는 하나의 bed안에 다른 하나의 bed를 넣음으로써 시스템이 차지하는 부피를 줄이는 한 건, inner bed와 outer bed 사이의 열교환 효과가 나타나기 때문에 그 효율을 높일 수 가 있다. 흡착탑의 동특성을 파악하기 위하여 4성분 (H2/CO2/CH4/CO, 69:26:3:2 vol. %)의 가스를 Feed rate 7LPM, Adsorption Pressure 9atm의 조건으로 실험을 하였다. Inner bed와 outer bed의 흡착 동특성의 차이를 알아보고, PSA 공정을 가상으로 하여 각각의 탑에서 흡착과 탈착이 동시에 일어날 때의 동특성도 알아보았다. 그리고 AD step time을 달리 하면서 PSA 공정에 알맞은 Sequence을 알아보았다.