• 대한화학회지
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• 제46권4호
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• pp.353-363
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• 2002

이 연구의 목적은 일반고와 과학고 학생들의 정신용량과 풀이 방법에 따른 산화 환원 반응식 완결 과정의 특성을 분석하여 산화 환원 단원의 교수학습 지도에 시사점을 얻고자 하는데 있다. 일반고 학생 79명과 과학고 학생 57명을 대상으로 하여 정신요량 검사, 산화 환원 반응식 완결 검사를 실시하였으며, 문항 유형별로 학생들의 문제 풀이 실패 유형과 성공 유형을 추출하여 분석틀을 개발하고 개발한 분석틀에 의하여 정신용량과 풀이 방법에 따라 실패 사례와 성공 사례를 분석하여 나타나는 특징을 알아보았다. 일반고 학생들과 과학고 학생들 모두 산화 환원 개념 이해 정도가 낮을수록 미정계수법을 많이 선택하였으며 미정계수법을 선택한 학생들은 정신용량이 클수록 문제 풀이의 성공률이 높았다. 또한, 산화 환원 개념 이해 정도가 높은 학생들은 산화수법이나 이온 자법을 더 많이 선택하였고 정신용량에 관계없이 문제 풀이의 성공률이 높게 나타났다. 학생들의 풀이 과정을 분석한 결과 성공 유형은 산화 환원의 개념 이해 정도가 높고 풀이 방법에 관계없이 풀이 단계 수를 줄이 학생들이었다. 실패 유형은 물이 방법에 따라 다르게 나타났다. 미정계수법을 선택한 학생들의 실패 유형은 계산 과정 중 틀린 경우, 미정방정식을 잘못 세운 경우 문제 풀이 과정중 고려해야 할 변인을 모두 고려하지 못한 경우 풀이 과정이 복잡하여 중단한 경우였다. 산화수법을 선택한 학생들의 실패 유형은 산화수를 잘못 결정한 경우 질량균형 또는 전하균형을 고려하지 않은 경우였다.

• Tribology and Lubricants
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• 제25권6호
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• pp.432-437
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• 2009

The effect of oxidation in SAE 5W30 engine oils on friction and wear characteristics was investigated using reciprocating bench tester and shell 4-ball tester. Commercial engine oils were collected and oxidized using the KS M 2021 method modifying the oxidation time. Kinematic viscosity, total acid number(TAN), FT-IR spectrum and total base number(TBN) also measured to examine the chemical change of oils with oxidation. The results showed that TAN was slightly changed and Kinematic viscosity was suddenly increased during the oxidation stage. however, TBN results keep a constant slope after TBN linearly decreased with oxidation time. Spectroscopy results showed that spectrums were orderly increased at $1710cm^{-1}$ during the oxidation time. Friction test results showed that oxidation of oils formed unstable friction layers causing higher fluctuating friction. however, the wear resistance was independent of oxidized time due to the different friction characteristics by oxidation. We found several factors in relation to lubrication properties with oxidation time. This factors were Viscosity, TBN, change of FT-IR spectrum, friction coefficient using reciprocating bench tester and wear scar.

• Corrosion Science and Technology
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• 제19권3호
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• pp.138-145
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• 2020

Immersion tests of Alloy 600 were conducted in simulated primary water environments of a pressurized water reactor at 325 ℃ for 10, 100, and 1000 h to obtain insight into effects of surface deformation on internal and intergranular (IG) oxidation behavior through precise characterization using various microscopic equipment. Oxidized samples after immersion tests were covered with polyhedral and filamentous oxides. It was found that oxides were abundant in mechanically ground (MG) samples the most. The number density of surface oxides increased with time irrespective of the method of surface finish. IG oxidation occurred in mechanically polished (MP) and chemically polished (CP) samples with thin internal oxidation layers. However, IG oxidation was suppressed with relatively thick internal oxidation layers in MG samples compared to MP and CP samples, suggesting that MG treatment could increase resistance to primary water stress corrosion cracking (PWSCC) from the standpoint of IG oxidation. As a result, appropriate surface treatment for Alloy 600 could prevent oxygen diffusion into grain boundaries, inhibit IG oxidation, and finally induce its high PWSCC resistance.

• Carbon letters
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• 제25권
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• pp.50-54
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• 2018

Large-size graphene samples are successfully prepared by combining ultrosonic assisted liquid phase exfoliation process with oxidation-deoxidation method. Different from previous works, we used an ultrasound-treated expanded graphite as the raw material and prepared the graphene via a facile oxidation-reduction reaction. Results of X-ray diffraction and Raman spectroscopy confirm the crystal structure of the as-prepared graphene. Scanning electron microscopy images show that this kind of graphene has a large size (with a diameter over $100{\mu}m$), larger than the graphene from graphite powder and flake graphite prepared through single oxidation-deoxidation method. Transmission electron microscopy results also reveal the thin layers of the prepared graphene (number of layers ${\leq}3$). Furthermore, the importance of preprocessing the raw materials is also proven. Therefore, this method is an attractive way for preparing graphene with large size.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.360-362
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• 1988

The new oxidation method was presented to grow the oxide layer by thermal reaction of $NH_{3}$ and $O_{2}$. The growth rate increased according as increase of partial pressure of $NH_{3}$. Optical transparent of the grown film was 12% compared with 17% of thermal oxidation when the wave number was $1,100cm^{-1}$. The oxide layer with good quaility was obtained.

• 대한전자공학회논문지
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• 제25권11호
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• pp.1329-1334
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• 1988

$NH_3-O_2$의 열반응에 의해 산화막을 성장시키는 새로운 방법을 소개하고, 기존의 건식산화방법을 이용한 $SiO_2$박막의 특성을 비교 설명하였다. $NH_3$의 유량에 따라서 박막의 성장비가 증가하고, 성장된 막의 구성성분이 건식산화때와 같음을 확인하였다. C-V특성곡선에서도 $Q_{OX}$와 $Q_{SS}$가 거의같았고 히스테리시스현상도 없었다. 또한 n-MOS트랜지스터를 제작하고 측정한 결과 $I_D$-$V_{DS}$특성곡선이 건식산화와 비교하여 우수함을 확인했다.

• 한국작물학회지
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• 제44권4호
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• pp.321-329
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• 1999

The effect of water deficits on soybean [Glycine max (L.) Merr.] could appear on seed quality through changes of morphological plant characteristics. Two Korean genotypes, Hwangkeum (determinate growth habit) and Muhan (indeterminate growth habit), were used to examine the influences of treatment stage and method of water deficit during reproductive growth period on yield and seed quality of soybean. Water deficit at R5 or R6 stages was as damaging to seed quality as double water-deficit treatments at R2+R5 or R2+R6. However, seed from double water-deficit treatment tended to have lower oxidation-reduction potential compare to the corresponding single water-deficit treatment. In comparison with Muhan, Hwangkeum had significantly greater oxidation-reduction potential value. Seed yield per plant in both genotypes depended greatly on seed yield of branches. However, the proportion of number of branch seed to total seed umber in Hwangkeum was increased as the water deficit was applied during later reproductive stage, whereas, in Muhan the proportion was lower. Water-deficit treatments including the single and double water-deficit treatments and non-stressed treatment were able to be classified into five groups for Hwangkeum and four groups for Muhan based on the influences on yield components, number of pod, number of seed, and single seed weight, using principal component analysis. In both genotypes, R2+R5 water-deficit treatment decreased number of pod and seed, but increased single seed weight. On the contrary, R6 or R2+R6 stress increased the pod and seed number, but decreased single seed weight.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.128-136
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• 2007

It is well known that two representative methods satisfy EURO-IV regulation from EURO-III. The first method is to achieve the regulation through the reduction of NOx in an engine by utilizing relatively high EGR rate and the elimination of subsequently increased PM by DPF. However, it results in the deterioration of fuel economy due to relatively high EGR rate. The second is to use the high combustion strategy to reduce PM emission by high oxidation rate and trap the high NOx emissions with DeNOx catalysts such as Urea-SCR. While it has good fuel economy relative to the first method mentioned above, its infrastructure is demanded. In this paper, the number distribution of nano PM has been evaluated by Electrical Low Pressure Impactor(ELPI) and CPC in case of Urea-SCR system in second method. From the results, the particle number was increased slightly in proportion to the amount of urea injection on Fine Particle Region, whether AOC is used or not. Especially, in case of different urea injection pressure, the trends of increasing was distinguished from low and high injection pressure. As low injection pressure, the particle number was increased largely in accordance with the amount of injected urea solution on Fine Particle Region. But Nano Particle Region was not. The other side, in case of high pressure, increasing rate of particle number was larger than low pressure injection on Nano Particle Region. From the results, the reason of particle number increase due to urea injection is supposed that new products are composited from HCNO, sulfate, NH3 on urea decomposition process.

• 한국전기전자재료학회논문지
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• 제20권1호
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• pp.1-7
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• 2007

In this paper, two kinds of initial oxidation methods i.e., SLTO(Slow Low Temperature Oxidation: $700^{\circ}C$) and RTO(Rapid Thermal Oxidation: $850^{\circ}C$) are applied prior to the plasma nitridation for ultra thin oxide of RPNO (Remote Plasma Nitrided Oxide). It is observed that SLTO has superior characteristics to RTO such as lower SS(Sub-threshold Slope) and improved Ion-Ioff characteristics. Low frequency noise characteristics of SLTO also showed better than RTO both in linear and saturation regime. It is shown that flicker noise is dominated by carrier number fluctuation in the channel region. Therefore, SLTO is promising for nano-scale CMOS technology with ultra thin gate oxide.

• Journal of Electrochemical Science and Technology
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• 제11권3호
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• pp.238-247
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• 2020

Some nano structured bimetallic NiPd electrocatalysts were electrodeposited on glassy carbon electrodes using a double potential step chronoamperometry. The morphology of the electrodeposited samples was investigated by field emission-scanning electron microscopy, while their compositions were evaluated using energy dispersive X-ray spectroscopy. It was observed that the electrodeposited samples contained a low Ni content, in the range of 0.80 - 7.10%. The electrodeposited samples were employed as the anode electro-catalysts for the oxidation of sodium borohydride in NaOH solution (1.0 M) using cyclic voltammetry, chronoamperometry, rotating disk electrode, and impedance spectroscopy. The number of exchanged electrons, charge transfer resistances, apparent rate constants, and double layer capacitances were calculated for the oxidation of borohydride on the prepared catalysts. According to the results obtained, the NiPd-2 sample with the lowest Ni content (0.80%), presented the highest catalytic activity for borohydride oxidation compared with the other NiPd samples as well as the pure Pd sample. The anodic peak current density was obtained to be about 1.3 times higher on the NiPd-2 sample compared with that for the Pd sample.