• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.651-656
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• 2001

Ascorbic acid(AsA) is unevenly distributed throughout all body cells and fluids. Multiactivities of AsA in many biological systems and in various scientific fields were reported. In this study we aimed to clarify the inhibitory action of high concentration of AsA on the cell growth in 3T6 fibroblasts. The cells wee exposed to AsA at various concentration. It showed that 3T6 fibroblasts wee dead by the medium which contained AsA at the concentration higher than 0.5 mM. AsA caused hydrogen peroxide ($H_2O$$_2$) generation in a concentration dependent manner. These results suggested that the $H_2O$$_2$ was formed in the medium by AsA and acted as a cytotoxic gent. Moreover, it is supposed that hydroxyl radical (.OH) induced from $H_2O$$_2$also acetd as actively cytotoxic agent. This lethal effect of AsA causing the cell death was inhibited by the addition of catalase in the medium. Therefore, addition of AsA at the normal concentrations stimulate cell growth, but excess concentrations of AsA induce cell death.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.99-102
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• 1999

본 연구에서는 대표적인 물리 화학적 토양정화방법인 토양세척기법의 효율증진을 위하여, Fe를 다량 함유한 고농도 윤활유 오염토양을 대상으로 알카리 용액과 산성용액의 세척효율을 비교 검토하고, 과산화수소의 첨가에 따른 세척효율의 향상효과를 알아보았다. 세척용제인 NaOH와 HCl를 이용하여 세척효율 검토 결과 NaOH를 이용한 경우에 약 60% 의 세척효율을 나타냈다. 또한 NaOH 농도에 따른 정화 효율은 각각 0.5% > 1% $\geq$ 2% 순서로 증가하였다. 기존의 세척효율을 향상시키기 위하여 과산화수소를 첨가하고 오염토양의 정화효율을 비교 검토한 결과 NaOH용액에서는 과산화수소의 농도가 증가할수록 정화효율이 증가하였으나 NaOH의 농도증가에 대해서는 큰 영향을 보이지 않았으며, NaOH 3%의 농도에서 과산화수소 1%를 첨가했을 때 85%의 정화효율을 나타냈다. 또한 과산화수소 주입시기에 따른 영향을 검토한 결과 세척 후 과산화수소를 주입한 경우에 정화효율이 높았다. 반면에 HCl의 경우는 HCl의 농도가 증가할수록 정화효율이 증가하였고, 세척하지 않고 과산화수소를 주입한 경우에 정화효율이 증가하였다. 고농도의 윤활유 오염토양의 세척효율을 증진시키기 위한 처리로서 과산화수소의 주입은 NaOH 상태에서 그 효율이 약 15%정도 증진되었으며, 일정시간에 이르면 정화효율이 평형에 도달하는 것을 알 수 있었다. HCl 상태에서는 25%의 정화효율이 증진되는 것을 알 수 있었다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.780-787
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• 2019

As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.52-57
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• 1998

The effects of additives such as zinc compounds in 4M KOH electrolyte of Al-air cell have been studied. Zinc compounds in electrolyte increased hydrogen evolution overpotential and TPC(tripotasium citrate)/CaO formed fine film on aluminum surface, and these additives decreased hydrogen evolution rate and corrosion rate of aluminum. These additives shifted the OCP in the positive direction on high purity aluminum(purity, 99.999%) and in the negative direction on Al No 1050(purity,99.5%). Addition of two or more additives resulted in the prevention or the reduction of corrosion rate and hydrogen evolution at OCP. As the overpotential on Al electrode increased, the hydrogen evolution rate decreased and the utilization of aluminum increased. At high current density$(>100mA/cm^2)$, TPC/CaO/ZnO additives increased the utilization of high purity aluminum up to that of aluminum alloys containing indium, gallium and thallium.

• Microbiology and Biotechnology Letters
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• v.5 no.3
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• pp.113-118
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• 1977

Into the precontaminated farm milk hydrogen peroxide ($H_2O$$_2$) was added at the concentrations ranging from 0.01％ to 0.05％ and kept at 3$0^{\circ}C$ for 16 hours with periodical determinations for viable counts, residual $H_2O$$_2$, and lactic acid. Under the tested conditions the initial level of contaminated bacteria could be arrested from growing at least for 8, 12, and 16 hours by treating the milk with 0.01, 0.02. and 0.03 per cent of $H_2O$$_2$, respectively. Furthermore, when the $H_2O$$_2$concentrations ware limited within the level of 0.03 Per cent the added $H_2O$$_2$was completely decomposed within 12 hours without the aid of external catalase and the decomposition time decreased in parallel with the $H_2O$$_2$ concentrations. A safer use of $H_2O$$_2$for preserving farm milk temporarily by limiting its concentration has been discussed.

• Journal of Environmental Health Sciences
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• v.14 no.1
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• pp.1-9
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• 1988

석탄유도가스에 포함된 황화수소를 제거시킬 흡착제를 개발하기 위하여 알칼리 토금속, 천이원소 및 아연의 이온반경보다 이온반경이 작은 금속산화물을 산화아연에 첨가시켜 다공성 흡착제를 제조하였다. 600$\circ$C에서 이들 첨가시료를 2.09vol.% 황화수소와 질소가스 혼합기체로 반응시켜 초기속도를 측정하고, 같은 온도에서 사용된 흡착제를 공기로 재생시켰다. 사용된 금속산화물 첨가 흡착제중에서 CaO, TiO$_2$, $Fe_2O_3$, CuO, $Ga_2O_3$ 및 Si$_2$O가 ZnO 흡착제의 초기속도를 증가시켜 첨가제로 사용할 수 있음을 보였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.237-242
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• 1998

Zr합금의 수소화 반응속도에 미치는 합금원소의 영향을 평가하기 위하여 Zr과 Zr-0.8Sn-XNb계열(X=0.2, 0.4, 0.8, 1.0) 및 Zr-0.4Nb-YSn계열(Y=0.5, 0.8, 1.5, 2.0)의 3원계 합금으로 electro-microbalance가 장착된 TGA (thermo-gravimetric apparatus)장치를 이용하여 40$0^{\circ}C$에서 1기압 수소와의 반응에 따른 무게증가를 in-situ로 측정하였다 Sn 첨가량이 증가함에 따라 1.5% 까지는 수소반응에 따른 무게증가율이 낮게 나타났으나 Sn을 2.0% 함유한 Zr-0.4Nb-2.0Sn합금의 경우 가장 높게 나타났다. 이는 Sn의 함량이 증가할수록 수소침투에 대한 저항성이 증가함을 의미하지만 Sn이 고용도 이상 함유되면 Sn을 함유한 다량의 석출물이 대량수소침투의 site로 작용하여 수소침투가 가속화된 것으로 평가된다. Nb의 경우 첨가량을 증가시킬수록 무게증가는 크게 나타났는데 이는 Nb이 수소흡수성이 크기 때문이며 Zr-0.8Sn-0.2Nb 및 Zr-0.8Sn-0.4Nb 합금보다 Zr-0.8Sn-0.8Nb 및 Zr-0.8Sn-1.0Nb 합금의 경우 TEM을 이용한 금속간 석출물(intermetallic precipitates) 분석에서 이러한 석출물들의 평균크기 및 개수가 크게 평가되었고, 또한 Zr-0.8Sn-0.2Nb, Zr-0.8Sn-0.4Nb 합금에서는 관찰이 되지 않는 $\beta$-Zr 석출물이 관찰되었다 이러한 사실로부터 Nb의 큰 수소흡수성에 부가적으로 이러한 석출물들이 수소침투를 가속화 하는 데에 기여하는 것으로 여겨진다.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.219-225
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• 2014

In this study, effect of cosurfactant on the solubilization rate of n-octane, n-decane and n-dodecane oil was performed by micellar solutions of polymeric nonionic surfactant Pluronic L64($EO_{13}PO_{30}EO_{13}$) at room temperature. It has been found that the solubilization rate of a hydrocarbon oil was enhanced with an increase in both chain length and amount of alcohol added. In case of addition of a short chain alcohol such as 1-butanol, the solubilization rate of a hydrocarbon oil was slightly increased since most of alcohol molecules remained in an aqueous surfactant solution. On the other hand, the addition of a relatively long chain alcohol such as 1-hexanol and 1-octanol produced a big increase in solubilization rate of a hydrocarbon oil mainly due to incorporation of alcohol molecules into micelles and thus producing more flexible micellar packing density. Dynamic interfacial tension measurements showed the same trend found in solubilization rate measurement. Both interfacial tension value at equilibrium and time required to reach equilibrium decreased with an increase in chain length of an alcohol.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.484-492
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• 1994

Microstructures of Nb$_2$O$_{5}$-doped UO$_2$ pellets have been investigated during sintering under H$_2$ and $CO_2$ atmospheres. Pellets are sintered at 1$700^{\circ}C$ in H$_2$ atmosphere and at 130$0^{\circ}C$ in $CO_2$ atmosphere for 1 to 41 hr. The addison of Nb$_2$O$_{5}$ causes the formation of large pores, which shrink to some extent in H$_2$ atmosphere but very little in $CO_2$. Fine pores in the Nb$_2$O$_{5}$-doped UO$_2$ pellet are almost annihilated when sintered under H$_2$ atmosphere but little changed under $CO_2$ atmosphere. The increase in grain size due to Nb$_2$O$_{5}$ addition is much larger in H$_2$ atmosphere than in $CO_2$. Thus the enhancement of uranium diffusion in UO$_2$ due to the Nb$_2$O$_{5}$ addition is thought to be more significant in H$_2$ atmosphere. Microstructures of Nb$_2$O$_{5}$-doped UO$_2$ pellets sintered in H$_2$ atmosphere are discussed from the viewpoint of in-reactor performance. Possible defects formation due to Nb$_2$O$_{5}$ addition is discussed to explain the enhancement of uranium diffusion in H$_2$ and $CO_2$ atmospheres.> atmospheres.

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.152-160
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• 1979

The promoting effect of Ba or Sr addition was investigated for furfural hydrogenation reaction over copper-chromium oxide catalysts. X-ray diffraction patterns showed the appearance of $BaCrO_4$ and $SrCrO_4$ phases in Ba, and Sr promoted copper-chromium oxide catalysts. For both Ba and Sr promoted catalysts, the activity decline with reaction time was much smaller compared to that of unpromoted catalyst and copper-chromium oxide catalyst dispersed on silica, reproducible EPR signals of Cr(V) were observed when CO was adsorbed. The promoting effect of Ba addition can be interpreted in terms of active sites dispersion and stabilization.