사출성형용 Stellite미분말의 소결 치밀화에 관한 연구

임태환 한국분말야금학회 1997 한국분말재료학회지 (KPMI) Vol.4 No.2

The densification of the compacts of Co+32%Cr+20%W+l.5%C, Co+32%Cr+20%W+3.0%C and Co+32%Cr+20%W+4.5%C sintered under $H_2$ gas or vacuum was investigated. The effect of V and B addition on the densification was also investigated. The densification of these compacts were always incomplete regardless of sintering atmosphere, temperature and time. The amounts of oxygen and carbon in compacts sintered in $H_2$ for 3.6ks at 1523K were 0.105~0.160 mass% and 0.33~0.89 mass%, respectively. And those in vacuum were 0.028~0.032% and 0.957~4.08%, respectively. Relative density(Ds) of Co+29%Cr+17%W+3.0%C compact containing 6%V and Co+32%Cr+20%W+2.97%C compact containing 0.03%B were 99 and 100%, respectively, indicating complete densification by solid phase sintering. Victors hardness of sintered compacts containing 6%V or 0.03%B were 632 and 568, showing 50~60% increase in comparison to those without V or B. These results can be explained in terms of oxidation/reduction of oxides and equilibrium pressure of CO in isolated pore, instead of presence of liquid formation and grain boundary separation from pores due to large grain growth.

자기공명위상영상법을 이용한 유체영상에서의 유속대별 영상특성

임태환 대한영상의학회 1996 대한영상의학회지 Vol.34 No.6

Purpose : To prepare a data base for semi-quantitative measurement of blood flow velocity on MR phase imagingtechnique by analyzing the characteristics of flow image according to the ranges of flow velocity. Materials and Methods : We obtained MR phase images of flow with velocity ranging from 0 to 70cm/sec. A straight flow tube with2.09cm internal diameter and a flow tube with 75% stenosis were used as flow phantoms for this study. MR imagings were performed on a 0.35 T MR imaging system. Results : At a velocity of 0-3cm/sec, the MR phase signal proceeded from an equivocal phase change to a homogeneous intraluminal signal intensity. Ata flow velocity of 3.1cm/sec,first phase wrap occurred, and there were two phase wraps up to 15cm/sec of flow velocity. In this velocity range, the MR phase image revealed an isocentric circular target appearance. At a velocity range of 15-30cm/sec, three to four phase wraps occurred, and the MR phase image showed a multiple target appearance. At a velocity above30cm/sec, the MR phase image showed an irregular unstructured appearance and above 50cm/sec, there were no flow signals and only noise-like signals were observed. The flow phantom of the stenosis model demonstrated the same phase image pattern as the high velocity flow in the stenotic and post-stenotic areas. In the pre-stenotic area, acharacteristic reversed laminar flow profile was observed. Conclusion : Flow velocity can be detected semiquantitatively as velocity ranges on MR phase imaging. The results of the experiment using a stenotic model suggest that MR phase imaging can be used as a modality for investigation of flow velocity and profiles.

카보닐(Carbonyl) Fe 미분기 진공 소결체의 산소량과 상대밀도에 미치는 탄소첨가의 영향

임태환 선문대학교 1994 鮮文論叢 自然科學 編 Vol.- No.4

지금까지 미량의 탄소(0.03mass%)를 함유하고 있는 사출성형용 카보닐 Fe미분(평균입도:5.3㎛ : 산소량:0.4maas%)에 대하여 소결치밀화 특성을 조사하였다. 그 결과를 예로 들면 일반의 승온속도(0.17Ks^(-1))에서 진공소결의 경우,(1)Fe소결체는 소결온도·시간 등을 변화시켜도 어느 경우에 있어서나 치밀화가 불완전하였다. (2)안정한 산화물을 형성하는 원소인 Al, Ti, Hb, V 등을 첨가하면 소결체의 치밀화는 완전하였다. (3)이와 같은 결과는 원료분말 중의 산화물(산소)과 탄소와의 환원반응에 의해 생성되는 고립기공 내에서 CO gas의 평형압과 표면응혁과의 대·소 관계에 의하여 설명 가능하다는 것을 명확하게 하였다. 그러나 이와 같은 진공소결체에는 원료분의 산화물(산소)이 거의 잔류하고 있어, 실제 제품으로 사용시 지장이 있을 것으로 생각하였다. 따라서 본 연구에서는 Fe 및 Fe+4%Al, Fe+4%Ti에 탄소분을 첨가하여 진공 중에서 환원조건을 변화시킴으로서 저산소 및 완전치밀한 소결체가 얻어질까를 조사하였다.

분말야금법에 의해 제조된 소결 GEAR 및 RATCHET의 조직 특성

임태환,이창순,박인규 선문대학교 중소기업기술지원연구소 1997 선문공대 연구/기술 논문집 Vol.2 No.1

Fe-χ%C-χ%Mn 강 제품의 파단 현상 개선에 관한 연구

임태환 선문대학교 ·중소기업기술지원연구소 1996 선문공대 연구/기술 논문집 Vol.1 No.1

와샤의 비틀림 가공시 재료가 파단되는 원인은 제품의 결정립이 조대화되었기 때문이라고 판정하였다. 따라서, 이와 같은 현상을 해결하기 위하여 소둔은도를 χ ℃로 약간 올려, 완전히 γ(austenite)구역으로 들어가게 하고, 소둔시간은 36분으로 단축하여 열처리하므로써, 불량품 생산량을 줄이고, 제품을 대량생산 할 수 있게 하였다. The reason of fracture during the forming of washers was thought o be due to the grain growth of the microstructure. To solve this problem, annealing temperature was slighty increased to χ ℃ so that a washer was fully austenized but annealing time was reduced to 36 minutes. By the treatment, it was enable to reduce the number of inferior goods and the mass production of the washers was possible.

fabrication of flexible PANI

임태환,오경화,김성훈 한국고분자학회 2010 한국고분자학회 학술대회 연구논문 초록집 Vol.2010 No.10

Pharmacokinetic Drug Interaction between Nifedipine and Gliclazide

임태환,김양우,최인 한국병원약사회 2016 病院藥師會誌 Vol.33 No.1

Gliclazide and nifedipine have been clinically prescribed for the prevention or treatment of cardiovascular diseases with diabetes. However, these drugs have potential interaction. The purpose of this study was to investigate the possible effects of gliclazide on the pharmacokinetics of nifedipine and its main metabolite, dehydronifedipine, in rats. We evaluated the effect of gliclazide on the activity of P-glycoprotein (P-gp) and cytochrome P450 (CYP)3A4. We determined the pharmacokinetic parameters of nifedipine and dehydronifedipine after oral and intravenous administration of nifedipine to rats in the presence or absence of gliclazide (1.0 and 4.0 mg/kg). Gliclazide inhibited CYP3A4 enzyme activity in a concentration-dependent manner with a 50% inhibitory concentration (IC50) of 12.5 μM. The areas under the plasma concentration-time curve (AUC0-∞) and the peak concentration (Cmax) of nifedipine were significantly (4.0 mg/kg, P<0.05) increased by 39.0% and 34.8%, respectively, in the presence of gliclazide, as compare to those of control. In addition, the total body clearance (CL/F) was significantly (4.0 mg/kg, P<0.05) decreased by the treatment with gliclazide (47.9%). Consequently, the absolute bioavailability (AB) of nifedipine in the presence of gliclazide (4.0 mg/kg) was significantly (P<0.05) higher (39.2%) than that of the control group. The metabolite-parent AUC ratio (MR) of nifedipine was significantly decreased by treatment with gliclazide (19.8%). The AUC0-∞ of intravenous nifedipine was significantly (4.0 mg/kg, P<0.05) higher than that of the control group (18.1%), which suggested that gliclazide inhibited the metabolism of nifedipine. The increased bioavailability of nifedipine in the presence of gliclazide may be due to an inhibition of the CYP3A4-mediated metabolism in the small intestine and/or in the liver and gliclazide-mediated reduction of CL/F of nifedipine.

철계 소결 부품의 최적 증기처리

임태환 선문대학교 ·중소기업기술지원연구소 2002 선문공대 연구/기술 논문집 Vol.7 No.1

조성이 서로 다른 Fe+0.7%C, Fe+O.7%C+1.6%Cu, Fe+0.7%C+0.3%MnS 혼합분말을 성형체의 밀도가 6.3, 6.5, 6.7, 6.9 g/㎤가 되도록 성형하고, 1125 ℃에서 30 분간 소결한 후 소결체 표면에 증기처리를 600 ℃에서 60 분간 실시하였다. 그 결과, 증기처리를 실시한 소결체의 중량 증가율, 소결체 속으로 산화물의 확산 속도, 표면 경도, 표면 생성 산화물 등의 증기처리 피막 특성에는 성형체의 밀도 및 첨가한 원소에 따른 증기처리 표면에서 생성되는 산화물 종류가 가장 큰 영향을 미치는 것을 알았다. Mixed powders of Fe+0.7%C, Fe+0.7%C+1.6%Cu and Fe+0.7%C+0.3%MnS were pressed in a mold so that the green-compact densities were 6.3, 6.5, 6.7, and 6.9 g/㎤, respectively. Then, the compacts were sintered at 1125 ℃ for 30 minutes and subsequently steam treated at 600 ℃ for 60 minutes. From the results, it was found that the overall properties of the steam-treated compacts, such as the weight gain of the sintered compacts, the diffusion of oxides into the sintered compacts, the surface hardness and the formation of surface oxide layer were primarily influenced by the density of the compacts and the oxides that were formed on the surface of the compacts by the steam treatment.

Highly conductive and transparent polyaniline film for organic solar cells anode

임태환,오경화,김성훈 한국고분자학회 2011 한국고분자학회 학술대회 연구논문 초록집 Vol.2011 No.1

Effects of Apigenin, an Antioxidant, on the Bioavailability and Pharmacokinetics of Etoposide

임태환,박선희,최준식 한국임상약학회 2011 한국임상약학회지 Vol.21 No.2

에토포시드와 아피제닌의 약동학적 상호작용 연구를 위하여 아피제닌 (0.4, 2.0 또는 8 mg/kg)과 에토포시드의 경구(6 mg/kg) 및 정맥 (2 mg/kg) 투여 하여 본 연구를 실시하였다. 아피제닌이 cytochrome P450 (CYP) 3A4 활성과P-glycoprotein (P-gp)의 활성에 미치는 영향도 평가하였다 아피제닌의 CYP3A4의 50% 효소활성억제는 1.8 μM 이었다. 아피제닌은 MCF-7/ADR 세포의 로다마인-123 세포 축적을 증가 시키므로 P-gp를 억제시켰다. 아피제닌은 에토포시드의 혈장곡선하면적과 최고혈장농도 (AUC and C_(max)를 유의성 있게 증가시켰으나, 에토포시드의 최고혈장농도 도달시간 T_(max)과 생물학적 반감기 (t1/2)에는 영향을 미치지 않았다. 따라서, 아피제닌 존재하에 에토포시드의 절대적생체이용률 (AB)은 대조군과 비교하여 유의성있게 증가되었다. 경구투여시와는 대조적으로, 아피제닌은 정맥 내로투여된 에토포시드에서는 약동학적 파라미터에 어떤 영향도 미치지 않았다. 따라서 아피제닌이 에토포시드의 생체이용률을 증가시킨 것은 아피제닌이 소장과 간장에서 CYP3A4을 억제 및 소장에서 P-gp를 억제 시켰기 때문으로 사료된다.