• Corrosion Science and Technology
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• v.22 no.6
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• pp.435-446
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• 2023

Corrosion behaviors of laser-welded super duplex stainless steel (SDSS) tubes after exposure to an actual power plant environment for one year and those of fin-tube welded SDSS were evaluated. Results showed that corrosion damage on the back side of the SDSS tube in the direction of hot air was higher than that on the front side regardless of weldment location. However, corrosion damage showed no difference between weldment and base metal due to recovery of phase fraction in the weldment through post weld heat treatment (PWHT). Nevertheless, the SDSS tube showed severe corrosion damage along grain boundary due to surface phase transformation (δ → γ) and Cr₂N precipitation caused by PWHT with a high N₂ atmosphere. Corrosion resistance of the SDSS tube was recovered when degraded surface was removed. Corrosion sensitivity of a fin-tube increased significantly due to pre-existing crevice, unbalanced phase fraction, and σ phase precipitation adjacent to the fusion line. Although corrosion resistance was improved by recovered phase fraction and sufficient dissolution of σ phase during PWHT, corrosion reaction was concentrated at the pre-existing crevice. These results suggest that welding conditions for fin-tube steel should be optimized to improve corrosion resistance by removing pre-existing crevice in the weldment.

• Journal of Food Hygiene and Safety
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• v.12 no.4
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• pp.315-320
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• 1997

Panax ginseng C.A. Meyer has been extensively used in the traditional oriental medicine as a restorative, tonic and prophylatic agent. This study was devised to develop a chemopreventive agent from panax ginseng to be able to suppress the genotoxicity and oxidative damage by ractive oxygen species, which are involved with cancer or aging. Ginseng petroleum ether extract (GPE) and one of its fraction, P2, showed an antioxidative effect on the lipid peroxidiphenyl-2-picryl hydrazil (DppH) radical generation. They also showed the suppressive effect of H2O2 or KO2 induced DNA damage by single cell gel electrophoresis (SCGE). Results from our study indicate that GPE and P2 are capable of protecting lipid peroxidation, and oxidative DNA damage. Therefore, GPE and P2 may be useful chempreventive agents which are involved with cancer and aging.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.128-129
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• 2016

This paper evaluates experimentally the explosion proof of fiber reinforced cement composite(FRCC) panels with various fibers of 2 % volume fraction subjected to contact explosions using an emulsion explosive. As a results, the proportion of the total damage in FRCC panels is not biased scabbing on the rear side with contrast to plain panels, which means that the local damage of FRCC panels was significantly controlled. The experimental results presented useful information for prediction of limited thickness on the local damage subjected to contact explosions through comparison with existing damage evaluation prediction equations.

• Journal of Acupuncture Research
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• v.19 no.2
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• pp.1-13
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• 2002

Objective ; In order to study the effect of Acanthopanax senticosus(AS) aqua-acupuncture manufactured with water soluble fraction and ether soluble fraction on the streptozotocin induced diabetic rats Methods ; The fractions of AS aqua-acupuncture were carried out on corresponding bilateral loci of Bisu(BL20) everyday for 4 weeks. The experimental animals were divided into control group and AS groups(AS water fraction group and AS ether fraction group). Thereafter the levels of serum glucose, total choleterol, HDL, triglyceride, AST, ALT, creatinine, BUN, urinary albumin excretion, index of kidney hypertrophy, heart rate, mean blood pressure and fibronectin in glomeruli and tubular cells were measured. Results ; The increased serum total cholestrol, triglyceride levels, HDL and urinary albumin excretion, the index of kidney hypertrophy, the mean blood pressure and the amount of fibronectin in glomeruli and tubular cells were significantly decreased in the AS groups, showing more significant decrease in the AS water fraction group as compared with the control group. In the serum ALT, AST, creatinine and BUN levels, there were no significant changes in the AS groups as compared with the control group. Conclusion ; According to the above results, it reveals that Acanthopanax senticosus water soluble and ether soluble fraction have the antidiabetic effect, the antilipidemic effect and the inhibitory effect of renal damage. Also, the results showed that Acanthopanax senticosus water soluble fraction is more effective than ether soluble fraction.

• Preventive Nutrition and Food Science
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• v.9 no.4
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• pp.352-360
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• 2004

To investigate the antioxidative effects of an etbylacetate fraction extracted from the flowers of Chrysanthemum indicum L. (Chrysanthemi Flos) on the antioxidative system and lipid profiles of rats with ethanol induced hepatotoxicity. Sprague-Dawley rats weighing $100\~150$ g were divided into 5 groups: normal group (NOR), Chrysanthemi Flos EtOAC fraction (200 mg/kg) treated group (S1), $35\%$ etbanol (10 mL/kg) treated group (S2), Chrysanthemi Flos EtOAC fraction (200 mg/kg) and ethanol concomitantly treated group (S3) and Chrysanthemi Flos EtOAC fraction (400 mg/kg) and ethanol concomitantly treated group (S4), respectively. The antioxidative activity of each fraction was decreased in order of EtOAC, n-hexane, n-BuOH, water and chloroform. The growth rates and feed efficiency ratios were decreased by ethanol treatment, but were gradually restored to similar levels as in the NOR group by administering Chrysanthemi Flos EtOAC fraction. The whole blood concentrations of total cholesterol and LDL-cholesterol, and the activities of ALT and AST that were elevated by ethanol were significantly decreased in the Chrysanthemi Flos EtOAC fraction treated groups. It was also observed that the activities of SOD, catalase, xanthine oxidase and GSH-Px elevated by ethanol in rat liver were markedly decreased in the Chrysanthemi Flos EtOAC fraction treated group as compared to S2. These results suggest that Chrysanthemi Flos EtOAC fraction has possible protective effects against ethanol induced hepatotoxicity in rat liver.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.97-99
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• 2012

A pressure-based BOIK model considering Shock to Detonation Transition(SDT) and damage due to external fragment or bullet stimuli impact on energetic materials and analytical approach for determination of free parameters are proposed. The rate of product mass fraction(${\lambda}$) consists of ignition term that represents the initiation due to shock compression and growth term that describes propagation of detonation wave and strain term representing the morphological deformation induced by external impact.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.167-170
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• 2004

In order to investigate the impact behaviors of 3-D braided glass/epoxy composites, the energy profiles and damage area were compared to the laminates of similar volume fraction and composition. The energy profiles showed different characteristics from each other which indicates they have distict energy absorption mechanisms. The image analysis on the damage projections visualized the crack propagation paths along the fiber direction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1455-1461
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• 1991

본 연구에서는 Kachanov의 재료손상(material damage)모델을 이용하여 새로운 수명예측식을 만들고, 이 수명예측식의 타당성을 조사하기 위하여, 최근에 발표된 크 립 수명과 기공분포와의 실험결과와 비교하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.296-303
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• 2001

Kachanov-Rabotnov(K-R) creep damage theory was reviewed, and applied to design a creep curve for type 316LN stainless steel. Seven coefficients used in the theory, i.e., A, B, k, m, λ, r, and q were determined, and their physical meanings were analyzed clearly. In order to quantify a damage parameter ($\omega$), cavity amount was measured in the crept specimen taken from interrupted creep test with time variation, and then the amount was reflected into K-R damage equations. Coefficient λ, which is regarded as a creep tolerance feature of a material, increased with creep strain. Mater curve with λ=2.8 was well coincided with an experimental one to the full lifetime. The relationship between damage parameter and life fraction was matched with the theory at exponent ${\gamma}$=24 value. It is concluded that K-R damage equation was reliable as the modelling equation for type 316LN stainless steel. Coefficient data obtained from type 316LN stainless steel can be utilized for life prediction of operating material.

• Nuclear Engineering and Technology
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• v.50 no.5
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• pp.673-682
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• 2018

One of the most widely used methods to estimate core damage during a nuclear power plant accident is containment radiation measurement. The evolution of severe accidents is extremely complex, leading to uncertainty in the containment dose rate (CDR). Therefore, it is difficult to accurately determine core damage. This study proposes to conduct uncertainty analysis of CDR for core damage assessment. First, based on source term estimation, the Monte Carlo (MC) and point-kernel integration methods were used to estimate the probability density function of the CDR under different extents of core damage in accident scenarios with late containment failure. Second, the results were verified by comparing the results of both methods. The point-kernel integration method results were more dispersed than the MC results, and the MC method was used for both quantitative and qualitative analyses. Quantitative analysis indicated a linear relationship, rather than the expected proportional relationship, between the CDR and core damage fraction. The CDR distribution obeyed a logarithmic normal distribution in accidents with a small break in containment, but not in accidents with a large break in containment. A possible application of our analysis is a real-time core damage estimation program based on the CDR.