• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.310-310
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• 2016

최근 NAND flash memory는 높은 집적성과 데이터의 비휘발성, 낮은 소비전력, 간단한 입, 출력 등의 장점들로 인해 핸드폰, MP3, USB 등의 휴대용 저장 장치 및 노트북 시장에서 많이 이용되어 왔다. 특히, 최근에는 smart watch, wearable device등과 같은 차세대 디스플레이 소자에 대한 관심이 증가함에 따라 유연하고 투명한 메모리 소자에 대한 연구가 다양하게 진행되고 있다. 대표적인 플래시 메모리 소자의 구조로 charge trapping type flash memory (CTF)가 있다. CTF 메모리 소자는 trap layer의 trap site를 이용하여 메모리 동작을 하는 소자이다. 하지만 작은 window의 크기, trap site의 열화로 인해 메모리 특성이 나빠지는 문제점 등이 있다. 따라서 최근, trap layer에 다양한 물질을 적용하여 CTF 소자의 문제점을 해결하고자 하는 연구들이 진행되고 있다. 특히, 산화물 반도체인 zinc oxide (ZnO)를 trap layer로 하는 CTF 메모리 소자가 최근 몇몇 보고 되었다. 산화물 반도체인 ZnO는 n-type 반도체이며, shallow와 deep trap site를 동시에 가지고 있는 독특한 물질이다. 이 특성으로 인해 메모리 소자의 programming 시에는 deep trap site에 charging이 일어나고, erasing 시에는 shallow trap site에 캐리어들이 쉽게 공급되면서 deep trap site에 갇혀있던 charge가 쉽게 de-trapped 된다는 장점을 가지고 있다. 따라서, 본 실험에서는 산화물 반도체인 ZnO를 trap layer로 하는 CTF 소자의 메모리 특성을 확인하기 위해 간단한 구조인 metal-oxide capacitor (MOSCAP)구조로 제작하여 메모리 특성을 평가하였다. 먼저, RCA cleaning 처리된 n-Si bulk 기판 위에 tunnel layer인 SiO2 5 nm를 rf sputter로 증착한 후 furnace 장비를 이용하여 forming gas annealing을 $450^{\circ}C$에서 실시하였다. 그 후 ZnO를 20 nm, SiO2를 30 nm rf sputter로 증착한 후, 상부전극을 E-beam evaporator 장비를 사용하여 Al 150 nm를 증착하였다. 제작된 소자의 신뢰성 및 내구성 평가를 위해 상온에서 retention과 endurance 측정을 진행하였다. 상온에서의 endurance 측정결과 1000 cycles에서 약 19.08%의 charge loss를 보였으며, Retention 측정결과, 10년 후 약 33.57%의 charge loss를 보여 좋은 메모리 특성을 가지는 것을 확인하였다. 본 실험 결과를 바탕으로, 차세대 메모리 시장에서 trap layer 물질로 산화물 반도체를 사용하는 CTF의 연구 및 계발, 활용가치가 높을 것으로 기대된다.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.291-301
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• 2004

In order to charaterize weathering of chalcopyrite and behavior of dissolved metal ions in waste rocks from Manjang Cu mine, mineralogical studies such as refractive microscope, XRD and SEM/EDS analyses carried out. The weathering was mainly occurred in fractures and edge of the chalcopyrite within the mine waste rocks. The weathering process can be seen to reflect four stages based on the weathering degree of chalcopyrite. The main secondary minerals are goethite, covellite, azurite, malachite and brochantite. Dissolved Cu and As were mainly adsorbed Fe-hydroxide. Poorly crystalline Fe-oxide contains relatively high As contents. In oxdizing condition, the weathering of chalcopyrite mainly occurs along the fracture, while the replacement of chalcopyrite observed mainly in the grain and produced covellite and brochantite. The dissolved metals (Cu, Fe, As) in waste rocks from the abandoned Manjang mine area could attenuate naturally by precipitation, adsorption and replacement reaction.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.93-102
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• 2023

This study investigated the possibility of treating heavy metal pollutants existing in the air in addition to simultaneously removing NOx and SOx by injecting oxidizing and reducing agents into a scrubber into a microbubble device to create an eco-friendly method that does not generate secondary pollutants. Lead compound (Pb) was selected as the heavy metal substance in the air to be treated with microbubbles, and the removal efficiency was confirmed. By treating microbubbles by connecting them to a scrubber, it was confirmed that not only NOx and SOx but also heavy metal substances in the air were reduced, cost was reduced, and secondary environmental pollutants were not generated. Through this study, it was possible to simultaneously remove NOx, SOx, and heavy metals at low cost by applying an eco-friendly method, rather than the existing high-cost treatment method such as SCR. If oxidizing agent, reducing agent, and microbubbles are used appropriately, economical and efficient air pollution can be achieved. Since material processing was possible, it is expected to be helpful in the technological development of environmental prevention facilities.

• Korean journal of food and cookery science
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• v.9 no.4
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• pp.317-322
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• 1993

Two kinds of simple and interesterfying mixed rapeseed oil were prepared according to add 30%, 50% and 70% of coconut and palm oil, then the physicochemical propecties such as the tedency of oxidation, foaming activity were Investigated. The initial AV and POV of interesterifyung mixed rape-seed oils were higher than those of simple mixed oils, but the tendencies of oxidation were similar. The intial value of IV interesterfied rapeseed oils was added in simple mixed rapeseed oil, Induction period were increased about 2.4~4 times. Induction period of intereterifyng mixed oils added palm ell increased about 2~3.2 times. While the foaming Buantity of interesterifing mixed rapeseed oils with palm oil were lower about 28~40% than those of the simple mixed rapeseed oils.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.359-363
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• 1987

Sonic waves (50KHz) was accelerated the oxidation reaction of primary, benzyl and secondary alcohol with $BaMnO_4\;and\;KMnO_4-CuSO_4{\cdot}5H_2O$ to give the corresponding aldehyde and ketone at $30^{\circ}C/1$ atm. in high yields compared to stirring or refluxing condition.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.85-92
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• 2011

Evaluation of the removal efficiencies of Fe(II) by reactive sand media coated with manganese (MCS), iron (ICS) and both of iron and manganese (IMCS) was investigated as functions of solution pH ranging from 2 to 9, reaction time and concentration of Fe(II) in a batch reactor using each reactive medium and additional oxidants such as $KMnO_4$ and NaOCl. When only Fe(II) was present in solution without any reactive medium, removal of Fe(II) was quite low below pH 5 due to a slow oxidation of Fe(II) and/or negligible precipitation but greatly increased above pH 5 due to a rapid oxidation of Fe(II) and subsequent precipitation of oxidized Fe species. ICS showed negligible efficiency on the removal of Fe(II) through adsorption. However, an efficient removal of Fe(II) was observed at low solution pH in the presence of IMCS or MCS through rapid oxidation and subsequent precipitation. Removal efficiency of Fe(II) by IMCS in the presence or absence of NaOCl was quite similar. Removal rate of Fe(II) by IMCS and additional oxidants gradually increased as the solution pH increased. From the kinetic experiments, removal pattern of Fe(II) was better described by pseudo-second-order equation than pseudo-first-order equation. A rapid removal of Fe(II) using IMCS in the presence of $KMnO_4$ was observed in the first 10 min. The initial removal rate of Fe(II) using $KMnO_4$ was 14,286 mg/kg hr. In case of using NaOCl, the removal of Fe(II) occurred rapidly in the first 6 hrs and then reached the near-equilibrium state. Removal of Fe(II) on IMCS was well expressed by Langmuir isotherm and the maximum removal capacity of Fe(II) was calculated as 1,088 mg/kg.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.547-552
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• 2010

A modified VIStA (vortex inertial staged air) burner was developed and used in a once-through-type boiler. For safety, the combustion in this burner is of the non-premixed type. An air damper is installed to control the distribution of air to each combustion chamber. The effects of the air-fuel ratio and air distribution on NOx formation were investigated. The newly modified VIStA burner gives NOx reduction effect by maximum 20% in the combustion chamber of a boiler, while it yields more uniform flame than the conventional burner.

• Food Science of Animal Resources
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• v.23 no.1
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• pp.86-95
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• 2003

Potential mechanisms by which vitamin E improves oxidative stability of myoglobin are documented. The basis by which this lipid-soluble antioxidant, ${\alpha}$-tocopherol, protects water-soluble oxymyoglobin is beginning to be understood. Recent evidence suggests that ${\alpha}$-tocopherol delays the release of prooxidative products of lipid oxidation from biomembranes, which in turn delays oxymyoglobin oxidation and the concomitant loss of desirable beef color. ${\alpha}$, ${\beta}$-Unsaturated aldehydes are one class of lipid oxidation products that enhance oxymyoglobin oxidation in vitro and appear to act by covalently binding to the protein. If ${\alpha}$-tocopherol delays the formation of these reactive aldehydes, then this could inhibit the prooxidative effect of these oxidation products toward oxymyoglobin. Additionally, ${\alpha}$-tocopherol may exert part of its color-stabilizing effect in beef by enhancing the metmyoglobin reduction.

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.460-464
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• 1990

Proton behavior was investgated for the redox reaction of trans-[$Co(en)_2(NO_2)Cl]^+$ with aqueous Fe(II) in acidic solution by UV/vis-spectrophotometric method. The reaction order of proton is first one and the rate constant(k$_H^+$) is 6.7 ${\times}\;10^{-1}L^2/mol^2{\cdot}min$. The values of $E_a$, ${\{Delta}H^{\neq}$, ${\{Delta}S^{\neq}$ are 14.5 Kcal/mol, 13.8 Kcal/mol and -18.3e.u., respectively. As the result of analysis of kinetic data, it has been found that this reaction proceeds through inner-sphere mechanism.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.642-650
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• 2005

This research investigates the effects of adding oxidants such as $Fe^0$, $Fe^{2+}$, and ${S_2O_8}^{2-}$ in the sonolysis of 1,4-D. Results indicate that the degradation could be divided into two steps (initiation and acceleration) kinetically. The initial portion agreed with zero-order expression, while the second portion could be fitted with pseudo first-order expression. In the presence of ${HCO_3}^-$, as a radical scavenger, the degradations of 1,4-D and TOC were suppressed, indicating that OH radical is an important factor in the sonolysis. The overall degradation efficiency of 79.0% in the sonolysis was achieved within 200 minutes. While $Fe^0$, $Fe^{2+}$, and ${S_2O_8}^{2-}$ were individually combined with sonication, the degradation efficiency of 1,4-D increased 18.6%, 19.1%, and 16.5% after 200 min, respectively. The addition of oxidants not only changed the kinetic model from zero to pseudo first order at initiation step, but also increased the rate constants in the acceleration step. The addition of oxidants in the sonolysis of 1,4-D also improved the mineralization of 1,4-D, however, the effect of adding oxidants on the rate increase was similar regardless of the oxidants.