• 한국축산식품학회지
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• 제23권1호
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• pp.86-95
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• 2003

비타민 E에 의한 육색소의 산화 안정성 향상 기작을 정리하였다. 지용성 산화제인 $\alpha$-토코페롤이 수용성 단백질인 옥시마이오글로빈을 보호하는 원리가 밝혀지고 있다. 최근의 연구들에서 $\alpha$-토코페롤이 세포막 지방산화의 2차 산화물들의 방출을 지연시켜 옥시마이오글로빈 산화를 억제시키고 식육의 바람직한 육색을 유지시킨다는 증거가 제시되고 있다. 지방산화물의 한 그룹인 $\alpha$,$\beta$-분포화 알데하이드들은 단백질과 서로 결합하는 역할을 하여 옥시마이오글로빈의 산화를 증진시키는 것으로 밝혀졌다. 만약 $\alpha$-토코페롤이 이런 활동적인 알데하이드들의 발생을 지연시킨다면 이런 지방산화물들이 옥시마이오글로빈의 산화에 미치는 영향도 억제될 것이다. 또한$\alpha$-토코페롤은 메트마이오글로빈의 환원에 작용하여 쇠고기의 육색 안정성 유지에 일정부분 역할을 담당하는 것으로 사료된다.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.71-80
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• 2012

To improve the $NO_X$ conversion over a SCR (selective catalytic reduction) catalyst, the DOC (diesel oxidation catalyst) is usually placed upstream of the SCR catalyst to enhance the fast SCR reaction ($4NH_3+2NO+2NO_2{\rightarrow}4N_2+6H_2O$) using equimolar amounts of NO and $NO_2$. Here, a ratio of $NO_2/NO_X$ above 50% should be avoided, because the reaction with $NO_2$ only ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$) is slower than the standard SCR reaction ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$). In order to accurately predict the performance characteristics of SCR catalysts, it is therefore desired to develop a more simple and reliable mathematical and kinetic models on the oxidation kinetics of nitric oxide over a DOC. In the present work, the prediction accuracy and limit of three different chemical reaction kinetics models are presented to describe the chemicophysical characteristics and conversion performance of DOCs. Steady-state experiments with DOCs mounted on a light-duty four-cylinder 2.0-L turbocharged diesel engine then are performed, using an engine-dynamometer system to calibrate the kinetic parameters such as activation energies and preexponential factors of heterogeneous reactions. The reaction kinetics for NO oxidation over Pt-based catalysts is determined in conjunction with a transient one-dimensional (1D) heterogeneous plug flow reactor (PFR) model with diesel exhaust gas temperatures in the range of 115~$525^{\circ}C$ and space velocities in the range of $(0.4{\sim}6.5){\times}10^5\;h^{-1}$.

• 공업화학
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• 제23권3호
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• pp.253-258
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• 2012

본 연구는 $Pd/TiO_2$ 촉매를 이용한 $CH_4$, CO 동시 산화반응에서 활성점 및 Pd의 산화 상태에 대한 영향을 조사하였다. Pd 함량이 증가할수록 Pd 종(PdO)의 결정성장을 야기시켜 $CH_4$ 산화반응 활성을 증진시켰다. 열처리를 통해 제조된 촉매표면의 Pd 산화상태에 따라 $CH_4$과 CO의 산화반응 활성이 상이한 결과를 나타내었다. XRD와 $H_2-TPR$ 분석으로 소성촉매는 $Pd^{2+}$종, 환원촉매는 $Pd^0$종이 우점하고 있음을 확인하였다. 또한, BET분석을 통해 촉매 활성인자인 비표면적 및 기공부피보다는 Pd의 산화상태가 촉매 활성에 미치는 중요한 인자임을 알 수 있었다. FT-IR 분석을 이용하여 Pd의 산화상태에 따른 $CH_4$과 CO의 반응 메커니즘을 확인할 수 있었다.

• 한국재료학회지
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• 제23권2호
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• pp.123-127
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• 2013

The electrolytic reduction of a spent oxide fuel involves liberation of the oxygen in a molten LiCl electrolyte, which is a chemically aggressive environment that is too crosive for typical structural materials. Therefore, it is essential to choose the optimum material for the process equipment for handling a molten salt. In this study, the corrosion behavior of pyro-carbon made by CVD was investigated in a molten LiCl-$Li_2O$ salt under an oxidation atmosphere at $650^{\circ}C$ and $750^{\circ}C$ for 72 hours. Pyro-carbon showed no chemical reactions with the molten salt because of its low wettability between pyro-carbon and the molten salt. As a result of XRD analysis, pyro-carbon exposed to the molten salt showed pure graphite after corrosion tests. As a result of TGA, whereas the coated layer by CVD showed high anti-oxidation, the non-coated layer showed relatively low anti-oxidation. The stable phases in the reactions were $C_{(S)}$, $Li_2CO_{3(S)}$, $LiCl_{(l)}$, $Li_2O$ at $650^{\circ}C$ and $C_{(S)}$, $LiCl_{(l)}$, $Li_2O_{(S)}$ at $750^{\circ}C$. $Li_2CO_{(S)}$ was decomposed at $750^{\circ}C$ into $Li_2O_{(S)}$ and $CO_{2(g)}$.

• Korean Chemical Engineering Research
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• 제44권2호
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• pp.193-199
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• 2006

${\gamma}-Al_2O_3$에 담지한 Cu-Mn 산화물 촉매에서 톨루엔 완전산화 반응을 $160{\sim}280^{\circ}C$의 온도 범위에서 고정층 반응기로 조사하였다. BET, SEM, TPR, TPO, XPS 및 XRD를 이용하여 촉매 특성분석을 하였다. 톨루엔의 완전산화 반응은 $280^{\circ}C$ 이하에서 이루어졌으며, 적절한 Cu-Mn 담지량은 15.0 wt％Cu-10.0 wt％Mn인 것으로 나타났다. TPR/TPO 및 XPS 분석 결과, 15 Cu-10 Mn 촉매의 산화환원 봉우리가 낮은 온도로 이동하였으며 결합에너지가 높은 값으로 이동하였다. XRD 결과, 고분산된 Mn 산화물과 CuO 보다 $Cu_{1.5}Mn_{1.5}O_4$의 촉매활성 인자로서의 역할이 더욱 우수한 것으로 추측되며, 촉매의 활성은 촉매의 산화환원 능력과 촉매의 높은 산화 상태에 기인하는 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제31권5호
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• pp.506-511
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• 1999

The pilot system for radioactive liquid laundry waste was developed with treatment capacity, 1ton/hr and set up in the Yong Kwang unit #4. The system is composed of tank module, RO systems and a UV/$H_2O$$_2$photo-oxidation unit. The RO system consists of the BW unit (low-pressure RO for brackish water desalination) and the SW unit (high-pressure RO for seawater desalination). The BW unit possesses 4 RO membranes and it can reduce the feed water volume down to 1/10. This concentrated feed water can be reduced again up to 1/10 in its volume in the SW unit composed of 4 RO membranes. The UV/$H_2O$$_2$ photo-oxidation process unit was used for the detergent degradation. The operation of the pilot system was carried out and verified in its capability through the continuous operation and concentration operation using the actual liquid waste from the power plant. The design criteria and data for industrialization were yielded. The efficiency of the UV/$H_2O$$_2$ photo-oxidation process and the optimum operational procedure were evaluated. The decontamination factors for radioactive cobalt and cesium were measured. This on-site test showed the experimental result in the DF$\geq$300 and volume reduction factor$\geq$100.

• 한국재료학회지
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• 제19권1호
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• pp.37-43
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• 2009

Silicon dioxide as gate dielectrics was grown at $400^{\circ}C$ on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of $O_2$ and $N_2O$ to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature $N_2O$ annealing, nitrogen can be supplied to the $Si/SiO_2$ interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/$SiO_2$ interface by plasma oxidation as the $N_2O$ molecule is broken in the plasma and because a dense Si-N bond is formed at the $SiO_2$ surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the $Si/SiO_2$ interface by the plasma oxidation of mixtures of $O_2/N_2O$ gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

• 공업화학
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• 제32권3호
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• pp.237-242
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• 2021

미세먼지와 함께 질소산화물, 황산화물, 휘발성 유기화합물, 암모니아 비롯한 유발물질에 대한 동시 저감기술은 엄격해지는 환경규제와 실질적인 저감효과 제고를 위해 꾸준히 주목받아 왔다. 오존산화에 의한 비수용성 질소산화물 고속산화 공정은 전통적으로 적용되고 있는 선택적 촉매환원 공정에 비해 공간절약형 시스템 적용을 가능하게 할 뿐만 아니라 운영비용 절감 측면에서 매우 효과적인 방법으로 평가되고 있으며 황산화물을 비롯한 산성가스와 동시 저감이 가능한 공정 구현이 가능하다는 장점까지 있다. 본 논문에서는 오존 고속산화 공정에 대한 기술 이슈 및 개발 동향을 소개하며 향후 산업적 이용 확대를 위한 개발 방향에 대해서 고찰하고자 한다.

• 한국축산식품학회지
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• 제42권4호
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• pp.580-592
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• 2022

The aim of the present study was to evaluate the effectiveness of Lycium barbarum polysaccharide (LBP) on lipid oxidation and protein degradation in Tan sheep meatballs during the frozen period. The meatballs were treated with LBP at 0.01%, 0.02%, and 0.03% and stored at -18±1℃ for 0, 3, 6, 9, and 12 weeks. The effects of LBP treatment were investigated using the contents of total volatile basic nitrogen (TVB-N), texture profile (TP), thiobarbituric acid reactive substances (TBARS), colour, and pH values, compared with 0.02% butylated hydroxytoluene treatment and the blank control. The results showed that LBP treatment significantly decreased TBARS content compared with the control, which confirmed LBP to be a highly effective component in preventing lipid oxidation of Tan sheep meatballs during frozen storage, and protein degradation in Tan sheep meatballs had a significant inhibition effect because of TVB-N value reduction. In addition, the colour, TP and pH values of meatballs treated with LBP were improved dramatically. To further determine the quality changes of the blank control and all treated groups during storage, the comprehensive score evaluation equation based on principal component analysis was obtained: Y=0.51632Y₁+0.29589Y₂ (cumulative contribution rate=81.221%), and the 0.02% LBP-treated group had a higher comprehensive score than the other groups, and the quality of LBP-treated meatballs was better as well. In summary, LBP may reduce or inhibit lipid oxidation and protein degradation, and enhance overall quality and shelf-life in prepared meat products.

• 한국재료학회지
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• 제17권9호
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• pp.458-462
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• 2007

The effect of oxygen in the synthesis of oxide nanowires by using carbothermal reduction process have been studied thermodynamically and kinetically. By using laboratory air, ZnO nanowires could be fabricated in the carbothermal reduction process and a metal oxidation process. As the processing pressure decreases, the diameter of the nanowires decreases and the oxygen vacancy increases. As the processing pressure increases, the oxygen vacancy decreases and the shape of the ZnO becomes plate-like.