• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.71-76
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• 1995

The thermal oxidation of Ge$_{0.2}$Si$_{0.8}$ in wet ambient has been investigated by Rutherford Backscattering Spectrometry(RBS). A uniform Ge$_{0.2}$Si$_{0.8}$O$_{2}$ oxide is formed at temperatures below 650.deg. C for polycrystalline and below 700.deg. C for single crystalline substrates. At higher temperatures Ge becomes depleted from the oxide and finally SiO$_{2}$ oxide is formed with Ge piled-ub behind it. The transition between the different oxide types depends also on the crystallinity of Ge$_{0.2}$Si$_{0.8}$. When a uniform Ge$_{0.2}$Si$_{0}$8/O$_{2}$ oxide grows, its thickness is proportional to the square root of the oxidation time, which suggests that the rate noting process is the diffusive transport of oxidant across the oxide. It is believed the oxidation is controlled by the competition between the diffusion of Ge or Si in Ge$_{0.2}$Si$_{0.8}$ and the movement of oxidation front.t.oxidation front.t.

• 대한전자공학회논문지
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• 제16권1호
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• pp.26-32
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• 1979

실리콘의 dry oxidation과 wet oxidation공정의 특성을 실험적으로 조사하였다. 산화온도는1,100℃, 1.150℃, 1.200℃를 사용하였고, 산소의 유량은 0.2 liter/min으로 부터 2.8 liter/min까지 변화시켰다. 산화막의 두께를 측정하여 0.1μ ∼ 1.0μ 을 성장시키는데 필요한 온도, 시간, 산소의 유량을 도표로 나타냈다. 산화막의 특성을 조사하기 위하여 유전 상수 절연파괴 전압, fixed surface charge density (Qss/q), mobile ciarge densify (Q /q)를 측정하였다. 측정 결과로부터 산화막이 MOS transistor에도 적합한 양질이라는 결론을 얻었다.

• 한국재료학회지
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• 제13권12호
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• pp.831-838
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• 2003

Anisotropic mesophase carbon fiber(AMCFs) was exposed to isothermal oxidation in air and $CO_2$atmosphere, and burn-off rates have measured by TGA. The microstructure changes of oxidized carbon fibers, were observed by SEM. It was observed that oxidation rate in the air is over 100 times faster than that in $CO_2$atmosphere. The activation energy obtained in air was about 43.4 Kcal/mole in the temperature range of $600∼800^{\circ}C$, and in $CO_2$was about 55.2 Kcal/mole in the temperature range of $950∼1200^{\circ}C$. Therefore, the oxidation reaction in both atmospheres was under chemical reaction regime in the above temperature ranges. It was shown that the oxidation of the AMCFs is initiated at the end of fibers at high temperature($1100^{\circ}C$) with developing the large pores, and the small pores are developed on the fiber surface at low temperature($900^{\circ}C$). In conclusion, the oxidation of the AMCFs is progressed through the imperfection.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권3호
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• pp.7-14
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• 2015

In this study, land farming and chemical oxidation of a diesel-contaminated site is compared to evaluate the environmental impact during soil remediation using the Spreadsheet for Environmental Footprint Analysis by U.S. EPA. Each remediation process is divided into four phases, consisting of soil excavation, backfill and transportation (Phase 0), construction of remediation facility (Phase 1), remediation operation (Phase 2), and restoration of site and waste disposal (Phase 3). Environmental footprints, such as material use, energy consumption, air emission, water use and waste generation, are analyzed to find the way to minimize the environmental impact. In material use and waste generation, land farming has more environmental effect than chemical oxidation due to the concrete and backfill material used to construct land farming facility in Phase 1. Also, in energy use, land farming use about six times more energy than chemical oxidation because of cement production and fuel use of heavy machinery, such as backhoe and truck. However, carbon dioxide, commonly considered as important factor of environmental impact due to global warming effect, is emitted more in chemical oxidation because of hydrogen peroxide production. Water use of chemical oxidation is also 2.1 times higher than land farming.

• Carbon letters
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• 제13권1호
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• pp.39-43
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• 2012

The size and the physical properties of graphene oxide sheets were controlled by changing the oxidation temperature of graphite. Graphite oxide (GO) samples were prepared at different oxidation temperatures of $20^{\circ}C$, $27^{\circ}C$ and $35^{\circ}C$ using a modified Hummers' method. The carbon-to-oxygen (C/O) ratio and the average size of the GO sheets varied according to the oxidation temperature: 1.26 and 12.4 ${\mu}m$ at $20^{\circ}C$, 1.24 and 10.5 ${\mu}m$ at $27^{\circ}C$, and 1.18 and 8.5 ${\mu}m$ at $35^{\circ}C$. This indicates that the C/O ratio and the average size of the graphene oxide sheets respectively increase as the oxidation temperature decreases. Moreover, it was observed that the surface charge and optical properties of the graphene oxide sheets could be tuned by changing the temperature. This study demonstrates the tunability of the physical properties of graphene oxide sheets and shows that the properties depend on the functional groups generated during the oxidation process.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1199-1203
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• 2012

Catalytic filters consisting of Ni nanoparticle and carbon fiber with different oxidation states of Ni (either metallic or oxidic) were prepared using a chemical vapor deposition process and various post-annealing steps. CO oxidation reactivity of each sample was evaluated using a batch type quartz reactor with a gas mixture of CO (500 mtorr) and $O_2$ (3 torr) at $300^{\circ}C$. Metallic and oxidic Ni showed almost the same CO oxidation reactivity. Moreover, the CO oxidation reactivity of metallic sample remained unchanged in the subsequently performed second reaction experiment. We suggested that metallic Ni transformed into oxidic state at the initial stage of the exposure to the reactant gas mixture, and Ni-oxide was catalytically active species. In addition, we found that CO oxidation reactivity of Ni-oxide surface was enhanced by increase in the $H_2O$ impurity in the reactor.

• 열처리공학회지
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• 제35권5호
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• pp.246-254
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• 2022

The high-temperature oxidation behavior of Cr-Mo steel AISI 4115 in air at different temperatures (600, 850, 950℃) for 120 min was studied by mass gain analysis, phase analysis (optical microscopy, electron probe micro-analysis, x-ray diffraction) and hardness measurement of each iron oxide-phase. The oxidation scales that formed on oxidation process consisted outer layer (Hematite), middle layer (Magnetite) and the inner layer (Chromite). In the case of 850 and 950℃, the oxidation mass gain per unit area of AISI 4115 steel increased according to the logarithmic rate as atmospheric pressure increased. Especially, It has been observed that with an increase in the atmospheric pressure at 600℃, the oxidation mass gain per unit area changed from a linear to logarithmic relationship.

• 한국응용과학기술학회지
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• 제34권2호
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• pp.367-375
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• 2017

본 연구에서는 배가스 내 존재하는 오염물질인 NO의 처리효율을 증대시키기 위하여 NO 산화공정을 연구하였으며, 강력한 산화력의 건식산화제를 제조하는 방법으로 $H_2O_2$ 촉매분해가 도입되었다. $H_2O_2$ 분해공정 상에서 적용 가능한 $K-Mn/Fe_2O_3$ 불균일계 촉매가 제조되었으며, 이들이 가지는 물리화학적 특성이 $H_2O_2$ 분해반응에 미치는 영향이 조사되었다. 제조된 건식산화제는 NO가 포함된 모사 배가스를 처리하기 위한 NO 산화공정에 적용되었으며, 다양한 모사 배가스의 유량(5, 10, 20 L/min)에서 약 100% 가까운 NO 전환율을 확인 하였다.

• 한국물환경학회지
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• 제23권5호
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• pp.600-606
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• 2007

Livestock wastewater containing concentrated organic matters and nutrients has been known as one of the major pollutants. It is difficult to apply the conventional activated sludge process to treat livestock wastewater because of high Non-biodegradable (NBD) matter and ammonia. The objectives of this study are to remove NBD matters including aromatic compounds and ammonia in livestock wastewater using Coagulation-Fenton oxidation-Zeolite (CFZ) processes and ascertain applicable feasibility in the field through pilot plant experiment. NBD matters and color remained in the treated water were removed over 92% by Fenton oxidation as the second treatment process. Ammonia was removed by over 99.5% in the zeolite ion exchange process as the last treatment method. From $UV_{254}$, $E_2/E_3$ ratio and GC/MS analyses of treated water at each process, the aromatic compound was converted to aliphatic and aromaticity was decreased. In pilot scale test, organics and ammonia removal efficiencies were not much different from the result of lab-scale test at various operation conditions. Furthermore, reaction time and dosage of Fenton reagent in pilot scale experiment reduced by 40 min and 50% rather than in lab-scale test. $BOD_5$, $COD_{Mn}$, SS, T-N and T-P of treated water in the pilot-scale experiment also met the effluent standards.

• 한국결정성장학회지
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• 제15권2호
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• pp.45-50
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• 2005

규소 표면의 기계적 손상은 산화 공정 중에 규소 표면에 여러 가지 형태의 결함들을 발생 시킨다. 규소 표면에 손상을 주는 마모 입자가 커짐에 따라 OISF보다는 etch pit의 형상이 동굴형인 선 결함(line defects)들이 많이 발생된다. 이들 결함들은 실리콘 결정을 성장시키는 단계에서 형성되는 결함들과는 상호 관련이 없다. 방향성 응고법으로 성장된 규소 결정속에 존재하는 결함들은 주로 twin과 stacking fault들이며 응고과정에서 발생이 예상되는 응력에 의한 전위는 거의 발견되지 않았다. 따라서 Czochralski 법으로 성장된 단 결정 규소뿐 아니라 방향성 응고법으로 성장된 다 결정 규소 기판도 표면의 결함들을 이용하여 extrinsic gettering을 통한 규소 결정 내부의 불순물 제거의 가능성이 높다.