• Korean Journal of Metals and Materials
• /
• v.46 no.7
• /
• pp.427-436
• /
• 2008

The effect of dewpoints on annealing behavior and coating characteristics such as wettability and galvannealing kinetics was studied by annealing 0.3wt%Si - 0.1~0.4wt% Mn added interstitial-free high strength steels(IF-HSS). The 0.3wt%Si-0.1wt%Mn steel exhibited good wettability with molten zinc and galvannealing kinetics after annealing when the dewpoint of $H_2-N_2$ mixed gas was above $-20^{\circ}C$. It is shown that the wettability and galvannealing kinetics are directly related to the coverage of the external(surface) oxide formed by selective oxidation during annealing. At $N_2-15%H_2$ annealing atmosphere, the increase of dewpoint results in a gradual transition from external to internal selective oxidation. The decrease of external oxidation of alloying elements with a concurrent increase of their subsurface enrichment in the substrate, showing a larger surface area that was free of oxide particles, contributed to the improved wettability and galvannealing kinetics. On the other hand, the corresponding wettability and galvannealing kinetics were deteriorated with the dewpoints below $-20^{\circ}C$. The continuous oxide layer of network and/or film type was formed on the steel surface, leading to the poor wettability and galvannealing kinetics. It causes a high contact angle between annealed surface and molten zinc and plays an interrupting role in interdiffusion of Zn and Fe during galvannealing process.

• Nuclear Engineering and Technology
• /
• v.52 no.1
• /
• pp.135-147
• /
• 2020

A methodology for evaluation of mechanical and thermal effects of localized non-axisymmetric oxidation in zircaloy claddings on LWR fuel reliability is proposed. To this end, the basic capabilities of the FALCON fuel behaviour code are used. Examples of methodology application to adjustment of selected operational limits for modern BWR fuel rods, to capture effects of the excess local oxidation, are presented. Specifically, the limiting rod internal pressure for the onset of cladding lift-off is reduced, depending on initial excess oxidation spot sizes. Also, the power limits for Anticipated Operational Occurrences are adjusted, to preclude fuel melting and cladding failure due to PCMI and PCI-SCC in the affected fuel rods.

• Journal of the Korean institute of surface engineering
• /
• v.33 no.5
• /
• pp.365-372
• /
• 2000

Pure $Fe_3$Al alloys with three different compositions of Fe-21.8%Al, Fe-24.1%Al and Fe-27.2%Al were prepared by vacuum induction melting followed by homogenization and hot forging. The long-time oxidation behavior of the prepared alloys was studied at 1073, 1273 and 1473k in air. The oxidation resistance greatly increased with an increase in Al contents. Thin and uniform oxide scales were always formed on Fe-27.2%Al, while thick and fragile oxide scales were formed on Fe-(21.8, 24.1%)Al. Internal oxidation was observed in Fe-(21.8, 24.1%)Al, when oxidized above 1273K. The major oxidation product of all the oxidized alloys was always $\alpha$-$Al_2$$O_3$.

• 연구논문집
• /
• s.29
• /
• pp.141-149
• /
• 1999

Brazing of Fe-Cr-Al alloy was carried out at $1200^{\circ}C$ in vacuum furnace using nickel-based filler metals : BNi-5 powder(Ni-Cr-Si-Fe base alloy} and MBF-50 foil (Ni-Cr-Si-B). The effect of boron content on the stability of oxide scale on the brazed joint was investigated by means of cyclic oxidation test performed at $1050^{\circ}C$ and $1200^{\circ}C$. Apparently, the joints brazed with MBF-50 containing boron showed relatively stable oxidation rates compared to boron-free BNi-5 at both temperatures. However, it was considered that the slower weight loss of MBF-50 brazed specimen wasn’t resulted from the low oxidation rate but from the spallation of oxide layer. The oxide layer consisted of thick spinel oxide on the surface and $Al_2 O_3$ internal oxide layer along the interface between mother alloy and braze, the mother alloy was also eroded seriously by the formation of spinel oxides such as $FeCr_2 O_4$ and $NiCr_2 O_4$ on the surface, likely to be induced by the change of oxide forming mechanism due to diffusion of boron from the braze. On the contrary, the joint brazed with BNi-5 showed the good oxidation resistance during the cyclic oxidation test. It seems that the oxidation can be retarded by the formation of stable $Al_2 O_3$ layer at the surface.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.175-176
• /
• 2022

By studying the characteristics of matrix insulated through heat generated through oxidation of iron powder, the basic research results on the possibility of buffering and applicability of Cold weather concrete as a curing method are presented. In order to prevent freezing due to a sharp decrease in temperature in the initial stage of curing, iron powder (Fe), powder activated carbon, which is a small amount of porous carbonaceous adsorbent, and salt (NaCl) as an oxidizing agent are replaced with iron powder admixture. As the curing temperature increases, the strength tends to increase, and when replacing the admixture at the same curing temperature, the strength slightly decreases. This is determined as a result of generating iron oxide through an oxidation reaction of iron powder, activated carbon, and NaCl generating a large amount of pores in the matrix. In addition, the internal temperature tends to increase as the mixing substitution rate increases, and it is judged that the oxidation heat of the iron powder mixture affects the increase of the internal temperature during curing. The higher the replacement rate of the iron powder mixture, the slightly lower the strength, but it is determined that freezing and melting that may occur in the early stage of curing can be prevented due to an increase in the initial internal temperature.

• The Journal of Internal Korean Medicine
• /
• v.29 no.2
• /
• pp.469-489
• /
• 2008

Objectives : The purpose of this study was to investigate the effects of Chungganhaeju-tang(Qingganjiejiu-tang) on alcoholic liver damaged by applying proteomics. Materials and Methods : Sprague-Dawley rats were used in this experiment the rats were divided into the normal group, the control group(alcohol) and the sample group(CGHJT +alcohol). The ethanol was orally administered twice a day for 6 weeks in the control and sample groups. Water instead of ethanol was orally administered twice a day for 6 weeks in the normal group. CGHJT extract was orally administered once a day for 6 weeks in the sample group. The livers of each group were processed and assessed by histology, Western Blot, $Oxyblot^{TM}$, CBB and 2-dimensional electrophoresis. Results : In the histological findings of the liver, CGHJT inhibited hepatic fibrogenesis induced by alcohol. TIMP-1 decreased in the sample group assessed by western blot and statistical significance was noted by dot blotting(p<0.05). In the $Oxyblot^{TM}$, protein oxidation induced by alcohol treatment decreased with CGHJT. In the 2-dimensional electrophoresis finding, increased proteins alcohol such as HSP 60, 60kDa heat shock protein, 3-mercaptopyruvate sulfurtransferase were normalized by CGHJT. CGHJT was considered to normalize the anti-oxidation activity elevated by alcohol. In the 2-dimensional electrophoresis finding, increased oxidized proteins such as actin, prolyl 4-hydroxylase beta polypeptide, 94kDa glucose regulated protein(GRP94), heat shock protein 90-alpha(HSC86), calreticulin precursor(CRP55), ATP synthase beta chain mitochondrial precursor, caspase-8 precursor, and dihydrolipoamide succinyltransferase(E2) decreased with CGHJT. CGHJT was considered to reduce the oxidative stress of alcohol. Conclusion : Chungganhaeju-tang(Qingganjiejiu-tang) exerts an inhibitory effect against the fibrosis and protein oxidation induced by alcohol treatment of rat liver. CGHJT was considered to normalize the elevated anti-oxidation activity by alcohol and to reduce the level of oxidative stress due to alcohol.

• Tuberculosis and Respiratory Diseases
• /
• v.38 no.4
• /
• pp.357-371
• /
• 1991

To identify the pathogenetic role of reactive oxygen free radical-induced oxidation reaction in endotoxin-induced acute lung injury, we infused endotoxin into 8 domestic pigs; endotoxin only (n=3), pretreatment with dimethylthiourea (DMTU) (n=5). We observed the sequential changes in hemodynamic parameters, the concentration of plasma oxidized glutathione (GSSG) in pulmonary arterial and venous blood, and albumin content in bronchoalveolar lavage fluid (BALF). The results were as follows. 1) While cardiac output decreased, mean pulmonary arterial pressure, pulmonary vascular resistance, and alveolar-arterial oxygen difference increased over phase 1 (0-2 hr) and phase 2 (2-4.5 hr) by endotoxin, DMTU attenuated the above changes only during phase 2. 2) While the concentration of plasma GSSG increased significantly by endotoxin during phase 2, there were no significant differences between pulmonary arterial and venous GSSG contents during both phases. The increase in plasma GSSG content was attenuated by DMTU. 3) The content of BALF albumin was significantly lower in DMTU group than that of endotoxin group. These results suggest that reactive oxygen free radical-induced oxidation reaction may have an important pathogenetic role in endotoxin-induced acute lung injury in pigs, which seems to be greater during phase 2 rather than phase 1.

• The Journal of Internal Korean Medicine
• /
• v.34 no.1
• /
• pp.1-13
• /
• 2013

Objectives : The purpose of this study was to investigate the effects of Jowiseungcheung-tang (JWSCT) extract on the lipid metabolism, anti-oxidation and inflammatory reflex. Methods : Male Sprague-Dawley rats were fed a high fat diet for 8 weeks and were randomly divided into 4 groups (10 mice in each group): control group, 100 mg/kg JWSCT group, 200 mg/kg JWSCT group, 300 mg/kg JWSCT group. The control group was administered 100 mg/kg of water, but the other three groups were administered 100, 200, 300 mg/kg JWSCT extract for 4 weeks. After 4 weeks, we measured lipid level, thiobarbituric acid reactive substance (TBARS), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and cytokines in plasma and liver. The gene expression level and the ratio of apo-B and apo-E were then investigated by way of reverse transcription -polymerase chain reaction (RT-PCR). Results : In the JWSCT group, compared with the control, free fatty acid, triglyceride, total cholesterol, LDL-cholesterol, TBARS, IL-$1{\beta}$, IL-6 and TNF-${\alpha}$ decreased significantly in plasma and liver. However HDL-cholesterol, IL-10, GSH-Px, SOD and CAT increased. In the JWSCT group, compared with the control, the gene expression level and the ratio of apo-A and apo-E decreased significantly in the RT-PCR analysis. Conclusions : The extract of JWSCT has anti-obesity, anti-inflammatory and anti-oxidant effects.

• Corrosion Science and Technology
• /
• v.7 no.2
• /
• pp.69-76
• /
• 2008

Common methods for large scale hydrogen production, such as steam reforming and coal gasification, also involve production of carbonaceous gases. It is therefore necessary to handle process gas streams involving various mixtures of hydrocarbons, $H_2$, $H_2O$, CO and $CO_2$ at moderate to high temperatures. These gases pose a variety of corrosion threats to the alloys used in plant construction. Carbon is a particularly aggressive corrodent, leading to carburisation and, at high carbon activities, to metal dusting. The behaviour of commercial heat resisting alloys 602CA and 800, together with that of 304 stainless steel, was studied during thermal cycling in $CO/CO_2$ at $650-750^{\circ}C$, and also in $CO/H_2/H_2O$ at $680^{\circ}C$. Thermal cycling caused repeated scale separation, which accelerated chromium depletion from the alloy subsurface regions. The $CO/H_2/H_2O$ gas, with $a_C=2.9$ and $p(O_2)=5\times10^{-23}$ atm, caused relatively rapid metal dusting, accompanied by some internal carburisation. In contrast, the $CO/CO_2$ gas, with $a_C=7$ and $p(O_2)=10^{-23}-10^{-24}$ atm caused internal precipitation in all three alloys, but no dusting. Inward diffusion of oxygen led to in situ oxidation of internal carbides. The very different reaction morphologies produced by the two gas mixtures are discussed in terms of competing gas-alloy reaction steps.

• Journal of Yeungnam Medical Science
• /
• v.34 no.1
• /
• pp.19-28
• /
• 2017

The incidence of type 2 diabetes mellitus and insulin resistance is growing rapidly. Multiple organs including the liver, skeletal muscle and adipose tissue control insulin sensitivity coordinately, but the mechanism of skeletal muscle insulin resistance has not yet been fully elucidated. However, there is a growing body of evidence that lipotoxicity induced by mitochondrial dysfunction in skeletal muscle is an important mediator of insulin resistance. However, some recent findings suggest that skeletal mitochondrial dysfunction generated by genetic manipulation is not always correlated with insulin resistance in animal models. A high fat diet can provoke insulin resistance despite a coordinate increase in skeletal muscle mitochondria, which implies that mitochondrial dysfunction is not mandatory in insulin resistance. Furthermore, incomplete fatty acid oxidation by excessive nutrition supply compared to mitochondrial demand can induce insulin resistance without preceding impairment of mitochondrial function. Taken together we suggested that skeletal muscle mitochondrial overloading, not mitochondrial dysfunction, plays a pivotal role in insulin resistance.