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Glucose - diethyldithiocarbamate 가 흰쥐의 약물 대사 효소에 미치는 영향
최병기(Byung Ki Choi),신혜주(Hye Joo Shin) 한국응용약물학회 2000 Biomolecules & Therapeutics(구 응용약물학회지) Vol.8 No.4
The modulation of cytochrome P450(P450) activities and glutathione S-transferase (GST) was investigated after i.p. administration of glucose-diethyldithiocarbamate (Glu-DDTC) to rats. P450 1A2 and 2E1 activities were inhibited by 60% 4 hr after the administration of 200 mg Glu-DDTC/kg and those activities were recovered to original levels 24 hr after dosing. In contrast, GST activities were enhanced up to 24 hr after dosing. These results seem to be due to the bifunctional activity of Glu-DDTC. Glu-DDTC acts as an inhibitor of P450 enzymes as well as inducer of GST enzyme. Glu-DDTC inhibited PNP hydroxylation (P450 2E1) and ethoxycoumarin O-deethylation (P450 1A2) in a dose-dependent manner up to 200 mg/kg wherease it did not affect testosterone 6β-hydroxylation (P450 3A) and pentoxyresorufin O-dealkylation (P450 2B) activities. Induction of GST activity toward 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzenen (DCNB) was dependent on the dose of Glu-DDTC and no species difference in the GST induction was seen between rat and mouse. Amoung GST subunits, Ya, Ybl and partially Yb2 were induced by Glu-DDTC as conjugated by western blotting. The levels Yp, Yk and Yc subunits were not affected by Glu-DDTC treatment. Therefore the enhanced activity of GST toward CDNB and DCNB might be due to the induction of Ya, Yb1 and partially Yb2 subunits. In conclusion, Glu-DDTC selectively inhibited P450 1A2 and P450 2E1 activities whereas it enhanced Ya, Yb1 subunits and partially Yb2 subunits of GST and the antimutagenic activity of this compound might be attributed from the modulation of these enzyme activities in animals.
Ni-Cr과 Co-Cr 합금을 이용한 치과보철물의 부식 특성 및 도재 접합성
김기정 ( Ki Jung Kim ),최병기 ( Byung Ki Choi ),오두록 ( Doo Rok Oh ),최병상 ( Byung-sang Choi ) 한국부식방식학회(구 한국부식학회) 2016 Corrosion Science and Technology Vol.15 No.3
By using Ni-Cr and Co-Cr alloys, porcelain fused to metal (PFM) samples were prepared to examine the interface and the surface corrosion behavior. The potentiodynamic polarization analysis showed that the corrosion current density of Co-Cr alloy (1.61×10-6A/㎠) was three times lower than that of Ni-Cr alloy (4.83×10-6A/㎠) at room temperature. A dental prosthesis consisting of the porcelain fused to Ni-Cr alloy extracted from a patient after approximately four years of usage was examined to assess its resistance to corrosion. OM and SEM images of the metal part revealed a typical pitting corrosion. As compared to porcelain fused to Ni-Cr alloy having a thick layer (~10 ㎛) of oxide at the interface, a relatively thin oxide layer (less than 5 ㎛) was formed on Co-Cr alloy, indicating that the interface between Co-Cr alloy and porcelain may have a better adhesion strength than the interface between Ni-Cr alloy and porcelain.
FRP 리프스프링의 이력특성 및 유한요소해석에 관한 연구
최병희 ( Byung Bui Choi ),이종범 ( Jong Bum Lee ),최병기 ( Byung Ki Choi ) 조선대학교 공학기술연구원 2009 공학기술논문지 Vol.2 No.2
Relations of deflection and load in the leaf spring of the suspension system have inherent nonlinearity caused by the inter leaf friction. performance of vehicles. Therefore, it is important that the hysteresis of leaf spring be properly described in order to improve the reliability of its design and analysis. In this thesis, to offer finite clement modeling for the leaf spring considering the inter leaf contact and friction. experimental method and FEM arc compared with. The load-deflection hysteresis curve that indicates the static characteristic of leaf spring is acquired by the experiment. Theoretical analysis is conducted based on the measured data. The static characteristic of leaf spring are predicted by MARC which is common software used in finite element analysis. Input conditions for analyzing the leaf spring using FEM arc verified. And for the FRP leaf spring hysteresis characteristics of each design model through finite element analysis was conducted.
응집된 Y<sub>2</sub>O<sub>3</sub>:Eu Red 형광체의 나노분산 및 나노졸의 형광특성
이현진,반세민,정경열,최병기,강광중,김대성,Lee, Hyun Jin,Ban, Se Min,Jung, Kyeong-Youl,Choi, Byung-Ki,Kang, Kwang-Jung,Kim, Dae Sung 한국재료학회 2017 한국재료학회지 Vol.27 No.2
Nanosized and aggregated $Y_2O_3:Eu$ Red phosphors were prepared by template method from metal salt impregnated into crystalline cellulose. The particle size and photoluminescent property of $Y_2O_3:Eu$ red phosphors were controlled by variation of the calcination temperature and time. Dispersed nanosol was also obtained from the aggregated $Y_2O_3:Eu$ Red phosphor under bead mill wet process. The dispersion property of the $Y_2O_3:Eu$ nanosol was optimized by controlling the bead size, bead content ratio and milling time. The median particle size ($D_{50}$) of $Y_2O_3:Eu$ nanosol was found to be around 100 nm, and to be below 90 nm after centrifuging. In spite of the low photoluminescent properties of $Y_2O_3:Eu$ nanosol, it was observed that the photoluminescent property recovered after re-calcination. The dispersion and photoluminescent properties of $Y_2O_3:Eu$ nanosol were investigated using a particle size analyzer, FE-SEM, and a fluorescence spectrometer.