• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.237-238
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• 1998

The kinetics of sulfite oxidation must be fast and the concentration of sulfite must be low to emulate oxygen uptake by blood. The kinetics were studied yielding a first order rate constant in sulfile, zero order in oxygen. Limitations of the technique were evaluated using the experimental rate constant and an adaptation of Lightfoot's approximation, while the reaction of hemoglobin is reversible and essentially instantaneous, that for sulfite is irreversible and finite. Thus if the approach to saturations not monotonic or if the mass transfer resistance is significantly lowered, e. g. when blood film thicknesses are thinner than a few hundred microns, deviations may occur.

• 한국조명전기설비학회지:조명전기설비
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• 제11권1호
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• pp.99-105
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• 1997

본 논문에서는 주상변압기 절연유의 가속열화반응을 수행하였다. 유중가스를 air bubbling 법으로 추출하여 가스크로마토크라프로 성분을 분석하였으며 가스농도는 각 가스의 추출율을 감안하여 보정하였다. 절연재료의 열화는 열분해반응과산화반응에의하여 진행되었으며 두 종류의 반응은 모두 0차반응의 특성을 보였고 탄화수소류, CO+{{{{ { CO}_{2 } }}}} 및 수소가스의 생성속도식을 얻었다. 유중가스 분석과 UV-Visible 분광광도법에 의하여 변압기내의 철심과 동코일이 열화과정에서 촉매역활을 함을 확인하였다.

• Molecules and Cells
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• 제39권1호
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• pp.26-30
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• 2016

Peroxiredoxins are ubiquitous thiol proteins that catalyse the breakdown of peroxides and regulate redox activity in the cell. Kinetic analysis of their reactions is required in order to identify substrate preferences, to understand how molecular structure affects activity and to establish their physiological functions. Various approaches can be taken, including the measurement of rates of individual steps in the reaction pathway by stopped flow or competitive kinetics, classical enzymatic analysis and measurement of peroxidase activity. Each methodology has its strengths and they can often give complementary information. However, it is important to understand the experimental conditions of the assay so as to interpret correctly what parameter is being measured. This brief review discusses different kinetic approaches and the information that can be obtained from them.

• 에너지공학
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• 제15권1호
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• pp.8-13
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• 2006

열중량 분석기와 XRD를 이용하여 $573\sim873K$의 온도범위와 이론밀도의 $94.64\sim99.10%$범위에서 $UO_2$ 핵연료 소결체의 공기 중 산화실험을 수행하였다. XRD를 이용하여 실험온도 범위에서 $UO_2$는 $U_3O_8$으로 산화되는 것을 확인하였다. 시간에 따른 산화반응은 S자의 형태를 나타내고 있어 핵생성과 성장의 과정을 따르는 것으로 나타났다. 밀도가 증가함에 따라 산화속도는 떨어지고, 산화유도시간은 늘어나는 것으로 나타났다. $UO_2$에서 $U_3O_8$으로의 산화에 대한 활성화 에너지는 $573\sim723K$의 온도범위에서 약 89.54kJ/mol, $723\sim873K$의 온도범위에서는 34.40 kJ/mol로 나타났다.

• 한국세라믹학회지
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• 제48권1호
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• pp.57-62
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• 2011

The T23 steel, whose composition was Fe-2.3%Cr-1.6%W, was arc-melted, and oxidized between $600^{\circ}C$ and $900^{\circ}C$ in air for up to 7 months. The amount of precipitates in the arc-melted microstructure was as large as 11.4 vol.%. The precipitates increased the oxidation rate of the arc-melted T23 steel. Owing to the low amount of Cr in the T23 steel, breakaway oxidation occurred after a few hours during oxidation above $700^{\circ}C$ in both arc-melted and as-received T23 steels. The scales that formed on arc-melted and as-received T23 steels were similar to each other. They consisted primarily of the outer $Fe_2O_3$ layer and the inner ($Fe_2O_3$, $FeCr_2O_4$)-mixed layer. The precipitates increased the microhardness and the oxidation rates.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.112-125
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• 2021

The new emerging "High entropy materials" attract the attention of the scientific society because of their simpler structure and spectacular applications in many fields. A novel nanocrystalline high entropy (Be,Mg,Ca,Sr,Zn,Ni)3O4 oxide has been successfully synthesized through mechanochemical treatment followed by sintering and air quenching. The present research work focuses on the possibility of single-phase formation in the aforementioned high entropy oxide despite the great difference in the atomic sizes of reactant alkaline earth and 3d transition metal oxides. Structural properties of (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide were explored by confirmation of its single-phase Fd-3m spinel structure by x-ray diffraction (XRD). Further, nanocrystalline nature and morphology were analyzed by scanning electron microscopy (SEM). Among thermal properties, thermogravimetric analysis (TGA) revealed that the (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide is thermally stable up to a temperature of 1200℃. Whereas phase evolution in (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide before and after sintering was analyzed through differential scanning calorimetry (DSC). Electrochemical studies of (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide consists of a comparison of thermodynamic and kinetic parameters of water and hydrazine hydrate oxidation. Values of activation energy for water oxidation (9.31 kJ mol-1) and hydrazine hydrate oxidation (13.93 kJ mol-1) reveal that (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide is catalytically more active towards water oxidation as compared to that of hydrazine hydrate oxidation. Electrochemical impedance spectroscopy is also performed to get insight into the kinetics of both types of reactions.

• 한국물환경학회지
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• 제38권5호
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• pp.211-219
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• 2022

In this study, the effect of liquid height/volume on sonochemical oxidation reactions was investigated in 300 kHz sonoreactors. The gas mixture of Ar/O₂ (50:50) was applied in two modes including saturation and sparging, and zero-order reaction (KI dosimetry) and first-order reaction (Bisphenol A (BPA) degradation) were used to quantitatively analyze sonochemical oxidation reactions. For the zero-order reaction, the highest sonochemical oxidation activity was obtained for the liquid height of 5𝛌, and the lowest height for both the gas saturation and sparging conditions. In addition, the sparging did not enhance the sonochemical oxidation activity for all height conditions except for 50𝛌, where very low activity was obtained. It was found that in sonochemiluminescence (SCL) images the sonochemical active zone was formed adjacent to the liquid surface for the gas sparging condition due to the formation of the standing wave field while the active zone was formed adjacent to the transducer at the bottom due to the blockage of ultrasound. For the first-order reaction, the highest activity was also obtained at 5𝛌 and the comparison based on the reactant mass was not appropriate because the concentration of the reactant (BPA) decreased significantly as the reaction time elapsed. Consequently, it was revealed that the determination of optimal liquid height (ultrasound irradiation distance) based on the wavelength of the applied ultrasound frequency was very important for the optimal design of sonoreactors in terms of reaction efficiency and reactor size.

• 환경위생공학
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• 제19권1호
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• pp.1-7
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• 2004

This study was conducted to supply basic informations on development of water treatment process for the ozonation of ammonia depend on pH variation with or without bromide catalysis. The results were as follows: The oxidation rate of ammonia increased depend on pH increase at ozone/bromide process. It was found that overall kinetics was zero order with respect to reaction time and reaction velocity constant of zero order increased depend on pH increase from 4.9 to 9.5 and the equation of linearization was $k_{o}$ = 0.00565 ${\times}$ [pH] + 0.0069 at ozone/bromide process. The denitrification reaction of ammonia was superior as the pH increase in the presence of bromide.

• E2M - 전기 전자와 첨단 소재
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• 제4권2호
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• pp.97-104
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• 1991

W/Si의 조성비가 2.6인 CVD텅스텐 실리사이드를 어닐링처리 하지 않고 바로 wet oxidation하여 polycide구조에서 다결정 실리콘 내의 인의 농도가 실리사이드의 산화반응 속도에 미치는 영향을 조사하여 직선-포물선적 속도법칙을 토대로 하여 분석 조사하였다. 텅스텐 실리사이드의 산화속도는 다결정 실리콘 내의 도편트 인의 농도가 증가함에 따라 증가하는 것으로 나타났다. 직선적 속도상수와 포물선적 속도상수 모두 인의 농도가 증가함에 따라 증가하는 경향을 보였다. 직선적 속도상수에 대한 활성화 에너지는 인의 농도가 증가함에 따라 감소하였으나 포물선적 속도상수에 대한 활성화 에너지는 인 농도와 무관한 것으로 나타났다.

• 대한화학회지
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• 제34권3호
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• pp.297-303
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• 1990

<ㅆㄸㅌ>$VO^{2+} 촉매가 존재하는 수용매에서 과산화수소에 의한 n-부틸아민의 산화반응은 n-부틸아민, 산 및 촉매인 VO^{2+}$농도에 대해서 각각 일차의존성을 보여주었다. 이 산화반응은 처음에는 이민중간물질이 생성된 다음에 가수분해되어 부틸알데히드와 암모니아를 생성한다. 이 반응의 속도결정단계는 n-부틸아민의 탈수소화반응이 일어나 이민이 생성되는 과정임을 제시한다.