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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.
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.
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.
김우곤(Kim Woo Gon),최병기(Choi Byung Ki),김욱(Kim Wook) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
정부는 제3차 전력수급기본계획 수립에 대비하고, 고가로 공급되는 LPG 수요를 대체하기 위한 제주도청의 LNG 공급요청과 제주지역에서 LNG사업을 희망하는 한국가스공사의 의향 그리고 한국전력공사의 전력연계선 추가건설 추진 등을 종합적으로 감안하여 이에 관한 세부 연구를 한국전기연구원에 위탁한 바 있다. 분석을 위한 전제 자료는 유관 사업자와 중립적 입장에 있는 한국전력거래소의 세밀한 검토와 합의를 거쳐 정해졌으며, 전력과 가스부문은 물론 이와 관련된 사회적 비용(Social Cost)이 모두 고려되었다. 아직까지 최종 결론은 확정되지 않았지만 연계선을 추가로 건설하는 방안이 가장 우세한 것으로 전해지고 있다. 따라서 본 논문은 추가 전력연계선 건설과 제3차 전력수급기본계획시 발전사업자가 제출한 제주지역에서의 발전소 건설 의향 등을 반영하여 2010년 이후 제주지역에서의 발전사업을 분석하고 전망하였으며, 예상되는 문제점을 중심으로 발전사업자 입장에서 개선방안을 제시하고자 하였다.
Yaw방향의 보정이 가능한 Tomotherapy couch device의 개발
채문기,권동열,선종률,최병기,Chae, Moon Ki,Kwon, Dong Yeol,Sun, Jong Lyool,Choi, Byung Ki 대한방사선치료학회 2018 대한방사선치료학회지 Vol.30 No.1
목 적 : "Yaw방향의 보정이 가능한 Tomotherapy couch device"를 자체 제작하였고, 그 유용성을 평가하였다. 대상 및 방법 : 휨 강도가 $200kg/cm^2$의 경질 섬유판 재질로 Yaw방향의 회전 가능한 Tomotherapy couch device를 제작하고, 제작된 device의 물리적 정확성을 판단하기 위해 Varian사의 Novalis Tx의 CBCT Image와 MED-TEC사의 Iso-Align Phantom을 사용하여 device의 Yaw방향의 보정각도의 정확성을 측정하였고, Tomotherapy HDA에서의 치료를 위해 치료계획은 Accuray PrecisionTM를 이용하여 In House Head and Phantom 위에 치료계획을 설계하였고 제작한 device의 보정각도마다 치료 전 후의 MVCT의 adaptive plan을 Accuray PrecisionARTTM and PrecisionTM을 사용하여 선량을 평가하였다. 결 과 : Yaw방향의 보정이 가능한 Tomotherapy couch device를 자체 제작하였으며, 물리적 정확성의 측면에서 모든 각도별 vertical, lateral, longitudinal의 보정값은 약 1 mm 내외였고, 최대 보정값이 1.5 mm를 넘지 않았으며 Yaw방향의 보정은 최대 0.12도 오차 이내의 범위 안에 들어왔다. 치료후의 MVCT촬영 영상을 이용한 adaptive plan을 이용한 선량 평가에서도 모든 각도실험에서 target은 D95=Prescription dose를 만족하고, target내 선량이 95 %~107 % 이내에 들어왔으며, OAR 또한 본원에서 평가한 SMC Head and Neck tolerance dose 영역 내에 모두 들어왔다. 결 론 : 자체 제작한 "Yaw방향의 보정이 가능한 Tomotherapy couch device는 Tomotherapy의 치료에서 Yaw방향의 set-up 오차를 정확히 보정해준다. 비용적인 측면에서도 효과대비 저비용으로 장치를 만들 수 있을 뿐만 아니라 재촬영에 대한 환자가 받는 MVCT image dose를 방지하고 시간적으로도 환자의 회전율을 상승시킬 수 있으며, Yaw방향의 set up 오차를 보정하므로 더 정확한 방사선치료를 시행할 수 있다고 판단된다. Objectives : A self-made "Tomotherapy couch device" capable of correcting the Yaw direction was fabricated and evaluated for its usefulness. Materials and Methods : "Tomotherapy couch device" capable of correcting the Yaw direction is made of rigid fibreboard with a flexural strength of $200kg/cm^2$. CBCT Image from Novalis Tx and Iso-Align Phantom from MED-TEC were used to evaluate the physical accuracy. The treatment plan was designed using Accuray $Precision^{TM}$ and In House Head and Phantom. Accuray $PrecisionART^{TM}$ and $Precision^{TM}$ was used to evaluate dose. Results : Evaluation results, the self-fabricated device accurately corrected the setup error, Target dose was within 95 %~107 % of all. In order to directly evaluate the OAR dose according to the Yaw change, the absolute dose was measured. As a result, when the error in the Yaw direction was $3^{\circ}$, the specific OAR showed a maximum difference of 18.4 %. Conclusion : "Tomotherapy couch device" capable of correcting the Yaw direction can be manufactured at a lower cost compared to the effect, and it can prevent the patient's MVCT image dose for re-imaging. Accurate radiation therapy without errors can be performed.