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알레르기성 소인이 없는 정상인에서 특이 알레르겐항체 양성율
남해선,안현철,박준수,황규윤,박춘식 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2
This study was designed to evaluate prevalence of allergen-specific antibodies in healthy adults. During Mar. ~ Aug. 2001, 1,925 subjects visited for medical check-up, were inquired to fill out a standardized questionnaire. Among them, 200 subjects who had no current and past allergic disorders were randomly selected for rhe current study and examined for allergen-specific antibodies using Korean inhalant panel of MAST-CLA allergen-specific IgE assay. Among them, 170 persons (85.0%) did not have any positive allergen-specific antibody. Each positive rate of 35 allergen specific antibodies was usually less than 3%, except Cockroach Mix (3.5%), Dermatophagoides farinae(8.5%), Dermatophagoides pteronyssinus(6.0%). Among 30 positive subjects, 19(63.3%) showed one or two allergen-specific antibodies. Although atopic subjects in non-allergic population were not common, few of them showed allergen-specific antibodies in Korean inhalant panel of MAST-CLA. Our results suggested that the standardized questionnaire and MAST-CLA could be an useful tool of a screening test for allergy, showing high specificity and sensitivity.
A Case of Oral-contraceptive Related Ischemic Colitis in Young Woman
Choon Sik Seon,Young Sook Park,Se Hwan Park,Sang Ryol Ryu,Yun Ju Jo,김성환,Byoung Kwan Son,Sang Bong Ahn 대한소화기내시경학회 2011 Clinical Endoscopy Vol.44 No.2
Ischemic colitis is generally considered a disease of the elderly. The causes of ischemic colitis include low-flow states due to cardiac dysfunction or hypovolemia and certain medications including estrogen. Here we report a case of ischemic colitis in a 26-year-old woman. She had no specific medical history except taking oral-contraceptives for a long time. The mechanism of estrogen-induced ischemic colitis is not clearly understood. But we recommend that oral-contraceptives should be considered as a cause of ischemic colitis in young women.
Nonstoichiometric Precipitation in As - Cast Mg - xAl - 1Zn Alloy
Choon, Sik,Shin, Kwang Seon,Lee, Choong Do 대한금속재료학회(대한금속학회) 2000 METALS AND MATERIALS International Vol.6 No.6
In the present study, the nonstoichiometric precipitation of the ß-phase in as-cast Mg-xAl-lZn alloy was investigated from the viewpoint of solidification behavior. ß-phase (Mg_(17)Al_(12)) has a nonstoichiometric composition of 28-41 wt.% Al and 6-12 wt.% Zn. Moreover, the chemical composition of the precipitate in MgxAl-lZn alloy locally varies depending on the Al content in the alloy and the solidification rate. However, it still maintains the same a-Mn structure as the ß-phase (Mg_(17)Al_(12)) in Mg-xAl alloy. Also, the slope of the calibration curve between the volume fraction of precipitate and intensity ratio (I_(pp)/I_(Mg)) is 0.35343 and 0.31995 in Mg-xAl and Mg-xAl-1Zn alloy, respectively.
Effect of an Mg - Rich Matrix on the Corrosion Behavior of As - Cast Magnesium - Aluminum Alloys
Kang, Choon Sik,Shin, Kwang Seon,Lee, Choong Do 대한금속재료학회(대한금속학회) 2000 METALS AND MATERIALS International Vol.6 No.5
In the present study, the corrosion behavior of as-cast Mg-Al and Mg-Al-Zn alloys was studied as a function of the A1 content in the matrix. Corrosion properties such as the corrosion rate, corrosion potential, and repassivation tendency were estimated through immersion and electrochemical tests. The corrosion potential and corrosion rate of a solutionized alloy depend mainly on the Al content of the as-cast alloy. The variation of Al content in the Mg-rich matrix influences the stability of the passive film and the repassivation tendency, i.e., as the Al content of the matrix increases, the repassivation tendency of the surface protective film after its breakage deteriorates. Also, it was proven that the enhancement of corrosion resistance by heat treatment, as in T6, is due to the decrease of solute concentration in the matrix, in addition to the effect of the precipitate, which plays the role of a barrier against corrosion.
마그네슘합금의 부식거동에 미치는 석출상의 Chunk Breakage
강춘식,신광선,이충도 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.1
In present study, the chunk breakage of precipitate and the negative difference effect which is a typical electrochemical behavior of Mg-alloy was investigated. In order to estimate the effect of precipitate, the calibration curves were obtained by XRD analyses(internal standard method). The chunk breakage of precipitate was observed under open circuit potential and maintained its original morphology. And, it revealed that the fraction of precipitate in corrosion products was approximately same as the fraction of precipitate in as-cast alloy. This is because of the corrosion behavior which the Mg-rich matrix is preferentially dissolved against the precipitate. Therefore, it was considered that the fraction of precipitate has a role of fixed factor on the corrosion rate of as-cast alloy. Also, the negative difference effect is arisen because the corrosion behavior of Mg-rich matrix is varied by the Al content, e. g. corrosion behavior of surface protective film. And, it reveals that the chunk breakage of precipitate operates only as a factor for the variation of the degree of difference effect(Δ).
Kang, Choon Sik,Shin, Kwang Seon,Lee, Choong Do 대한금속재료학회(대한금속학회) 2000 METALS AND MATERIALS International Vol.6 No.4
In the present study, the corrosion behavior of an as-cast magnesium alloy was studies focusing on the galvanic corrosion between a precipitate and Mg-rich matrix. Through immersion and electrochemical tests, the variation of the corrosion behavior with the alloy composition and alloy system was discussed in detail. The corrosion rate of an as-cast alloy increased abruptly to 9 wt.% A1 in both alloys, but in the composition range of over 12 wt.% Al, the corrosion rate reveals a different tendency than the alloy system. The ß-phase that is a typical precipitate in an Mg-xAl alloy is a more potent cathodic phase than is the ternary precipitate in a Mg-xAl-lZn alloy. In the case of the Mg-xAl alloy, the formation of a galvanic cell between the precipitate and matrix promotes the preferred dissolution of the matrix, but the precipitate in the Mg-xAl-lZn alloy has a minor effect on the corrosion behavior of the Mg-rich matrix. However, the corrosion rate of as-cast MgxAl and Mg-xAl-lZn alloys which contain precipitate, depends mainly upon the corrosion behavior of the Mg-rich matrix, which is influenced by the Al content. It depends additionally upon the variation of the Anode-Cathode Area Ratio (ACAR) and the chunk breakage of precipitate during corrosion.
플라즈마 용사한 NiCrAlY/NiCrAlY+8wt%Y2O3-ZrO2/8wt%Y2O3-ZrO2 3층 단열코팅층의 특성에 관한 연구
이선호,강춘식,유재성 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.6
Thermal barrier coatings(TBCs) fabricated by plasma spray process is generally used for gas turbine and diesel engine to improve their efficiency and service life. In this study, intermediate mixed layer between bond and ceramic layer was sprayed to improve thermal shock lifetime through increase of adhesion strength. On spraying the mixed Layer, each melted droplet of bond and ceramic powder was not mixing. Thus, interface shape between bond and ceramic Layer showed the complicated morphology. The adhesion strength and the thermal shock lifetime were improved by maximum 1.2 and 1.5 times. respectively. It was judged that improvement of thermal shock lifetime was due to increase of adhesion strength and tensile residual stress. From the stress analysis of thermal shock procedure. it was proved that enlargement of fractured region was occurred because horizontal crack in the vicinity of interface propagated in the direction of surface.