• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.19 no.2
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• pp.95-102
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• 2013

Exfoliated graphite (EFG) with high aspect ratio was incorporated with high density polyethylene (HDPE) for use as high barrier packaging material such as water-sensitivity electric product and pharmaceutical packaging. Also HDPE/EFG nanocomposite films were prepared by adding the compatibilizer for effective dispersion and compatibility. Their chemical properties, crystal structure properties, thermal properties and water barrier properties of as-prepared HDPE/EFG nanocomposite films were investigated as a function of EFG contents. It showed that there is a weak interfacial interaction between HDPE and EFG, however, the water vapor permeations were decreased from 127 to 78 (70 ${\mu}m{\cdot}g/m^2$, $day{\cdot}atm$) by addition of EFG. Especially, the physical properties of HDPE/EFG nanocomposite films were effectively increased up to 0.5 wt%, however, there were no significant improvement of properties in nanocomposite films at the additional EFG loading. To maximize their performance of the nanocomposite films, further research is required to enhance the dispersion of EFG and compatibility of EFG in HDPE matrix.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.519-523
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• 2018

Cyclodextrins are a class of oligosaccharides having an extremely low toxicity, so that they have been used for the formation of host-guest complexes and removal of toxic gases or molecules. In this study, the subtle phenomenon associated with the formation of host-guest complexes between cyclodextrin and toxic molecules (methyl paraben) was experimentally investigated. First, the formation of cyclodextrin-methyl paraben complexes was monitored by UV/Vis spectroscopy as a function of the cyclodextrin concentration. Secondly, the electrochemical measurement was performed with the surface engineered Au electrode having cyclodextrin molecules on the Au substrate. The sensing signal derived from the addition of methyl paraben solution into the Au surface was measured delicately. This study can be informative for future applications such as sensors.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.191-198
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• 2005

Hippuryl-L-histidyl-L-leucine (Hip-L-His-L-Leu, HHL) is the known substrate of ACE, which used often in inhibition kinetic study to design new inhibitor. Here we use HHL molecule as a template to predict pharmacophore which can interact with residues in active site of AnCE, new potential insecticide target protein. To explain physicochemical properties related to molecular geometry and conformational change in reaction field as well as electron density of atoms associated to pharmacophores, geometry optimization, NMR chemical shifts and natural population analysis were performed by ab initio and DFT method. Calculated NMR chemical shifts showed good agreement with the experimental ones and obtained electron densities were used for analyzing pharmacophores of corresponding atoms. Finally, we could extract aye pharmacophores related to hydrophobic aliphatic and aromatic site, hydrogen bonding donor and acceptor site and Zn binding site from the HHL molecule.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.45-47
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• 1997

정밀여과 및 한외여과에 의해 단백질 등과 같은 거대분자 물질을 분리정제할 경우 피할 수 없는 문제점은 막에 의해 분리된 거대부자들이 막표면에 쌓이는 농도분극(concentration polarization)현상과 이 누적된 거대분자가 막과의 상호작용에 의해 막표면 또는 막세공 내에 비가역적으로 침적되는 막오염(membrane fouling)현상이 일어난다는 점이다. 특히 막표면 또는 막세공 내에 분리대상 물질이 비가역적으로 침적되어 발생되는 막오염은 상대적으로 가역적 침적 과정인 농도분극보다 제어 또는 억제가 어려워 최근의 막분리 분야 연구의 상당 부분이 막오염 유발요인의 해석, 막오염을 효율적으로 제어 또는 억제하기 위한 방법의 연구에 집중되고 있다. 본 연구에서는 단백질 용액의 정밀여과시 단백질 변성이 막오염에 미치는 영향을 체계적으로 규명하기 위한 연구의 일환으로서 BSA를 분리대상 물질로하여, BSA용액을 미리 기계적 Shear(펌프 및 sonification), 열, 화학적 방법(pH 및 변성제)으로 변성시킨 후, 이 용액을 대상으로 회분식 정밀여과 실험을 수행하여 단백질 응집체 형성이 막투과량 감소에 미치는 영향을 실험적으로 검토하였으며, 각각의 막투과량 감소 특성을 아래의 4가지 blocking filtration law로서 해석하였다: complete blocking law, intermediate blocking law, standard blocking law, cake filtration law.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.483-494
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• 1988

The adsorption behavior of aromatic acids on Amberlite XAD-4 resin was investigated by measuring the distribution coefficient by batch method. The adsorption of solutes on XAD-4 was affected by the several factors such as, analyte concentration, the pH of solution and concentration of pairing ion. The enhanced adsorption of solutes on XAD-4 in the presence of tetraalkylammonium salt as an ion pairing reagent, referred to as ion interaction, was suggested to follow a double layer model where the pairing ion occupies a primary layer at the adsorbent while the solute anion and other anions in the system comlpete for the secondary layer. Therefore, the ability of an ion pairing reagent to enhance solute adsorption depended significantly on the type and concentration of counter-ion and co-anion accompanying the ion pairing reagent or salt used for ionic strength control. In addition, a good linear relationship between the logarithm of capacity factors measured by batch and elution method as a function of the concentration of ion pairing reagent and methanol can be used to predict the retention in elution method on the basis of capacity factors measured by batch method.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.947-954
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• 1992

Polyethylene glycol (PEG) grafted poly (γ-benzyl L-glutamate) (PBLG) was synthesized by the substitution reaction of PBLG and PEG having primary amino groups at both ends. PEG-g-PBLG films containing hydroxyl group were also prepared by the substitution reaction of PEG-g-PBLG film and ethanolamine (EA). Adhesion of platelets and activation of plasma proteins on the copolypeptide films were studied. The results showed that platelets are less adhered and activated on the PEG-g-PBLG than on other polypeptides and plasma recalcification time (PRT) on the PEG-g-PBLG was longer than that on other polypeptides. These results were consistent with those of blood clotting time and thrombus formation on the polypeptides. As a results, PEG-g-PBLG surfaces showed better blood compatibility than PBLG or PEG-g-PBLG-EA surfaces.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.802-811
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• 1992

The conformations of several carbene-olefin-transition metal complexes[$(CO)_4M$-(CHX)olefin] (X: $OCH_3,\;NHCH_3,\;SCH_3$, M: C, Mo, W) have been studied by means of Extend Huckel calculations. In the case of $d^6$ transition metal octahedral complexes, it is shown that the two main factors which determine the optimal conformation are metal-to-ligand back-donation and direct ligand-ligand interaction at the metal, but the ligand-ligand interaction dominates the situation for a metal that is coordinated to $\pi$ acceptor ligands and to $\pi$ donor group on the carbene. The relative amounts of both factors depend strongly on the electronic nature of the ligands at the metal. The greater electron donating ability of nitrogen stabilizes amino-substituted carbene complexes compared with their alkoxyl substituted analogues. This interaction is optimal when the $\pi$ systems of the carbene and olefin are coplanar. The introduction of the $\pi$ donor group on the carbene carbon increases also the importance of the ligand-ligand interaction.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.463-466
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• 2006

직접 알콜 연료전지는 액체인 알콜을 직접 연료전지에 공급하여 연소시킴으로써 높은 효율을 갖는 휴대용전원으로 주목받는 장치이다. 직접 알콜 연료전지에 담지체로 사용되는 탄소 소재는 넓은 표면적과 우수한 전기전도도를 가지고 있다는 장점 있으나 금속 촉매와의 상호작용이 약하여 촉매 활성에 영향을 주지 못한다. 산화물을 담지체로 사용할 경우 이러한 금속-담지체 간의 상호작용으로 인한 촉매활성 증가 및 입자성장 억제의 효과를 기대할 수 있다. 본 연구에서는, 안티몬 도핑된 주석산화물 (Sb-doped SnO2 : ATO nanoparticle)을 직접 메탄올 연료전지용 담지체어 적용하였으며 합성 과정은 다음과 같다. SnC14 5H2O SbC13, NaOH, HCl 수용액 혼합물을 삼구 플라스크에 넣고 $100^{\circ}C$ 온도에서 환류(reflux) 시킨 후 세척 및 건조하여 Air 분위기에서 열처리하였다. 합성된 산화물 수용액에 폴리올 방법으로 합성된 백금 콜로이드를 담지하였으며, 세척과 건조를 통하여 산화물에 담지된 백금 촉매를 촉매를 합성하였다. 촉매의 구조분석을 위해 XRD, TEM을 사용하였으며, 전극촉매로서의 활성을 평가하기 위해 cyclic voltammetry을 평가하였다. 본 연구에서는 백금의 담지량에 따른 Costripping voltammetry특성과 메탄올 및 에탄올 산화 반응 특성에 대하여, 탄소를 담지체로 사용한 Pt/C 촉매와 비교 평가하였다. 알콜 산화반응 평가결과, 주석산화물에 담지한 촉매가 탄소를 담지체로 사용한 촉매보다 우수한 활성을 나타내었으며 활성증가는 메탄올에 비해 에탄올 산화 반응의 경우 크게 증가하였다. 막과 비교해 보았다. $ZrO_2$ 입자는 전도성이며 동시에 친수성을 나타내기 때문에 상용 막에 비하여 함수율 및 수소이온 전도도가 우수하게 나타났다. 복합막의 이러한 물성은 $100^{\circ}C$이상의 고온에서 전해질 막 내의 물 관리를 용이하게 한다. 단위 전지 운전 온도 $130^{\circ}C$, 상대습도 37%의 운전 조건에서도 상당히 우수한 전지 성능을 보임에 따라 고온/저가습 조건에서 상용 Nafion 112 막보다 우수한 막 특성을 나타냄을 확인하였다.소/배후방사능비는 각각 $2.18{\pm}0.03,\;2.56{\pm}0.11,\;3.08{\pm}0.18,\;3.77{\pm}0.17,\;4.70{\pm}0.45$ 그리고 $5.59{\pm}0.40$이었고, $^{67}Ga$-citrate의 경우 2시간, 24시간, 48시간에 $3.06{\pm}0.84,\;4.12{\pm}0.54\;4.55{\pm}0.74 $이었다. 결론 : Transferrin에 $^{99m}Tc$을 이용한 방사성표지가 성공적으로 이루어졌고, $^{99m}Tc$-transferrin의 표지효율은 8시간까지 95% 이상의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{99m}Tc$<

• Journal of Korea Water Resources Association
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• v.52 no.11
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• pp.917-929
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• 2019

Denitrification in streams is of great importance because it is essential for amelioration of water quality and accurate estimation of $N_2O$ budgets. Denitrification is a major biological source or sink of $N_2O$, an important greenhouse gas, which is a multi-step respiratory process that converts nitrate ($NO_3{^-}$) to gaseous forms of nitrogen ($N_2$ or $N_2O$). In aquatic ecosystems, the complex interactions of water flooding condition, substrate supply, hydrodynamic and biogeochemical properties modulate the extent of multi-step reactions required for $N_2O$ flux. Although water flow in streambed and residence time affect reaction output, effects of a complex interaction of hydrodynamic, geomorphology and biogeochemical controls on the magnitude of denitrification in streams are still illusive. In this work, we built a two-dimensional water flow channel and measured $N_2O$ flux from channel sediment with different bed geomorphology by using static closed chambers. Two independent experiments were conducted with identical flume and geomorphology but sediment with differences in dissolved organic carbon (DOC). The experiment flume was a circulation channel through which the effluent flows back, and the size of it was $37m{\times}1.2m{\times}1m$. Five days before the experiment began, urea fertilizer (46% N) was added to sediment with the rate of $0.5kg\;N/m^2$. A sand dune (1 m length and 0.15 m height) was made at the middle of channel to simulate variations in microtopography. In high- DOC experiment, $N_2O$ flux increases in the direction of flow, while the highest flux ($14.6{\pm}8.40{\mu}g\;N_2O-N/m^2\;hr$) was measured in the slope on the back side of the sand dune. followed by decreases afterward. In contrast, low DOC sediment did not show the geomorphological variations. We found that even though topographic variation influenced $N_2O$ flux and chemical properties, this effect is highly constrained by carbon availability.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.607-624
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• 2018

We review SAFT equation of state (EOS) which is based on TPT theory and statistical-mechanical principles, and confirm that it can be used as a useful tool to predict vapor-liquid phase equilibria of associating fluid mixtures. We examine theoretical structure of PC-SAFT EOS in great detail, and then assess the applicability and performance of the EOS while applying it to various mixtures containing nonpolar components, polar components and associating components in a stage-wise manner. In contrast to the conventional engineering EOS, PC-SAFT EOS can accurately predict nonideal behaviors of those mixtures without using semi-empirical binary interaction parameter. This is because the SAFT theory is based on a rigorous theoretical framework at molecular level which effectively accounts for various intermolecular interactions, and it thus provides substantial benefits in applying the SAFT EOS to complex thermodynamic phenomena of multi-component mixtures.