• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.1-8
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• 2005

In this study, $TiO_2$ powders were prepared by hydro-thermal synthesis with titanium tetra isopropoxide. The prepared $TiO_2$ and the commercial $TiO_2$(P-25, Degussa) were by impregnating $H_2PtCl_6$ solution or the leached solution from the waste catalytic converter of automobile. Modified photocatalysts were analyzed by ICP-AES, UV-DRS, XRD, SEM. And band-gap energy of modified photo-catalyst was found to decreased to 1.76eV and basic structure was changed upon modification by leached solution. Modified photocatalysts were coated on the wallpaper after using mixed solution with adhesive materials(PVC). And then to know the modified photo catalysts tested the reactivity and quantum efficiency in the mixed gas with NO as reactants in the photo catalytic reactor. In the gas phase, photo-catalytic activity of NO was the highest for modified P-25 catalysts(P-25(w)) that P-25(w) was impregnated by leached solution of wasted catalytic converter.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.241-250
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• 1990

Characteristic relaxation time and characteristic diffusion time of viscoelastic fluids are determined experimentally by measuring the zero-shear-rate viscosity by falling ball viscometer and the infinite-shear-rate viscosity by capillary tube viscometer. Fluids used in experiments are aqueous solutions of polyacrylamide Separan AP-273 and the polymer concentrations range from 300 to 2000 wppm. A newly designed laser beam and timer system is employed to overcome the difficulty in measuring terminal velocities of the low concentration solutions. Ball removal device is prepared to remove the dropped ball from the bottom of cylinder without disturbing the testing fluid. In order to measure the zero-shear-rate viscosity, densities of hollow aluminium balls are adjusted very close to the densities of testing fluids. Characteristic diffusion time, which is ball viscometer. However, terminal velocity of a needle by falling ball viscometer is not affected by the time interval of dropping needles and characteristic diffusion time is not measured with a dropping needle. Powell-Eyring model predicts the highest values of the characteristic relaxation times among models used for heat transfer experimental works for a given polymer solution. As degradation of a polymer solution continues, the zero-shear-rate viscosity decreases more seriously than the infinite-shear-rate viscosity. Characteristic relaxation times of polymer solutions decreases as degradation continues.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.68-68
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• 2003

오늘날 형질전환동물의 생산과 같은 생명공학기술의 발달로 인하여 우리나라 재래산양은 그 모델동물로서 번식 생리학적으로 매우 중요한 가치를 지니고 있을 뿐만 아니라 고유의 유전자원 보존 측면에서도 산양복제와 같은 다양한 연구가 절실히 요구된다. 따라서 본 연구에서는 이러한 생명공학기술의 기초자료를 제공하고자 난포란의 활성화 방법과 단위발생란의 체외발달율을 조사하였다. 성숙한 미경산 재래산양을 공시동물로 하여 CIDR를 이용하여 발정동기화를 시켰으며, 과배란 처리는 FSH와 hCG를 이용하여 과배란 처리를 실시하였고 난포란의 회수는 외과적 방법으로 개복하여 난소의 난포로부터 난자와 난포액을 흡입하여 회수하였다 난포란의 활성화 처리는 전기자극법과 약물처리 방법을 사용하였으며, 전기자극방법은 DC 2.36㎸/cm, 17$\mu$sec 전압으로 1회 전기자극을 가하여 활성화를 유도하였으며, 약물처리법은 5$\mu\textrm{g}$/$m\ell$의 ionomycin 용액에서 5min, 1.9mM 6-DMAP용액에서 4시간동안 처리하여 활성화를 유도하였다. 단위발생란의 배양은 10% GS(goat serum)가 첨가된 M16 배양액과 10% FBS가 첨가된 TCM-199 배양액에서 난관상피세포와 6~7일동안 공배양을 실시하면서 체외발달율을 조사하였다. 활성화 방법에 따른 체외발달율은 전기자극 및 약물처리를 하였을때 분할율은 3.1% 및 67.9%였으며, 상실배 및 배반포로의 발달율은 0% 및 7.9%였다. 단위발생란의 체외 발달율은 10% GS가 첨가된 M16 배양액을 사용하였을 때 분할율은 68.0%였으며, 이중 12.0%가 상실배 또는 배반포로 발달하였다. 뿐만 아니라 10% FBS가 첨가된 TCM-199 배양액에 난관상피세포와 공배양을 실시하였을 경우는 72.0%가 분할하였으며, 이중 16.7%가 상실배 또는 배반포로 발달하였다. 이상의 결과로 볼 때 활성화 처리는 ionomycin과 6-DMAP 용액처리가 적합하며, 단위발생란의 체외배양은 보다 적합한 배양조건의 확립이 필요한 것으로 생각된다.

• Polymer(Korea)
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• v.25 no.1
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• pp.108-114
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• 2001

Crosslinked poly(glycerol-co-malate)s were synthesized from L-malic acid in Krebs cycle and glycerol. The synthesized polymer was identified by FT-IR spectroscopy. Swelling degrees of the copolymer hydrogels were increased with an increase in pH of the aqueous solution. Hydrolytic behaviors of the crosslinked copolymers were investigated in various pH buffer solutions at 37${\circ}C$. The Hydrolysis of the copolymers proceeded faster with increasing pH of the aqueous solution. Releasing behaviors of the model drug such as diclofenac monosodium salt were also measured in various pH aqueous solutions at 37${\circ}C$. The release concentration of diclofenac monosodium salt from the hydrogel systems was increased with increasing pH. These facts indicate that the unreacted carboxyl and hydroxyl groups in the copolymers are greatly affected by pH in the conditions.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.676-680
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• 2003

Dissolution of magnetite powders by 0.05 M citric acid was investigated at $50^{\circ}C$. All the tests were performed in the pH range between 2.0 to 5.0, which was adjusted using nitric acid or sodium hydroxide. Concentration of each of the dissociated chemical species of citric acid under various solution pHs was calculated using the ionization constants. Variation of zeta potential of magnetite with pH changes was also investigated. The dissolution reaction was explained by comparing the concentration of the dissociated chemical species of citric acid with the zeta potential. Longer than 3 h of induction time was required to dissolve the magnetite. The dissolution behaviour of magnetite was well described by the equation. The physical meaning of each parameter was explained successfully from the model equation.

• Economic and Environmental Geology
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• v.35 no.2
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• pp.149-154
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• 2002

Column tests were carried out to examine the effect of surfactant solution conditions on surfactant-enhanced remediation of contaminated soil. The selected conditions of the surfactant solution were concentration and pH. 1,2,4-trichlo-robenzene (TCB) was chosen as the model hydrophobic organic substances. Sodium diphenyl oxide disulfonate (DOSL) and octylphenoxypoly ethoxyethanol (OPEE) surfactants were selected for this study. Two Iowa soils, Fruitfield sand and Webster clay loam, were leached with surfactant solution. The test results revealed that an optimum condition was achieved for 4 %(v/v) of concentration and 10 of pH, respectively. The maximum recoveries of added TCB (93-98%) were obtained when optimal conditions of each surfactant solution parameter were simultaneously met. The optimum conditions of these parameters may be useful for surfactant-assisted remediation in soil contaminated by TCB.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.667-673
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• 1998

Rebar corrosion in a simulated pore solution (SPS) with chloride ion was analyzed by Tafel and AC impedance method and corrosion effects of surface roughness and iron oxide layer were also investigated. Corrosion estimation of rebar by electrochemical impedance spectroscopy is very useful, and the measured value can be adapted to proposed electrochemical equivalent circuit model. Corrosion potential increased to the cathodic direction as the concentration of chloride ions increased and corrosion current had the same tendency as above. Surface films were analyzed with scanning electron microscope and Auger electron spectroscopy. Thermally oxidized layer by torch flame for 15 sec was very poor at anti-corrosive property. The corrosion rate of rebar increased as the surface roughness increased. Also, higher temperatures above RT of SPS in initial stage caused a rebar to be corroded faster.

• KSBB Journal
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• v.17 no.3
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• pp.295-301
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• 2002

The effects of nonionic surfactant (SPAN 20) on the desulfurization process by Rhodococcus sp. strain IGTS8 have been investigated at various oil/water ratios, pHs and concentrations of surfactant. The hexadecane containing DBT was employed as model oil. The presence of surfactant in the oil/water mixture stabilized the oil/water interface, thus enhanced the efficiency of desulfurization. The volume percentages of oil in the oil/water mixture were 30, 50 and 70%. The concentrations of surfactant were varied from 0 to 0.33 wt% relative to water phase. In general, the biodesulfurization efficiencies were decreased as the concentration of SPAN 20 and the volume percentage of oil phase increased.

• The Korean Journal of Food And Nutrition
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• v.10 no.4
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• pp.462-467
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• 1997

The DIS process(dewatering and impregnation soaking process) are using for dewatering of food materials at room temperature. And the DIS process are resulted in diffusion process as well as dewatering phenomena. During the DIS process, plasmolysis or cytorrhysis was happened by according to solute size. A tissue state of food material was very important variables for movement of water or solute, and running conditions are important for dewatering and impregnation. And models for DIS process were fundamentally given by Fick's law at unsteady state or mass balance. For example, Bicompartmental Model was given for quantification of water loss and solid gain.

• Resources Recycling
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• v.15 no.2 s.70
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• pp.45-49
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• 2006

The removal of copper ion from aqueous solution by adsorption with bone char that made from spent pig bone has been studied. This paper was studied the effects of bone char dosage and pH. The optimal results show that bone char adsorbs about 96.5 percent of copper ion in aqueous solution containing 50 mg/L as initial concentration at pH 5.0 when the bone char of 5g/L is used for 30 hours. Increase in the initial pH of the copper solution resulted in an increase in the copper ion uptake per weight of the sorbent Freundlich isotherm model was found to be applicable for the experimental data of $Cu^{2+}$.