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단섬유로 강화된 Nylon 6.6/Ionomer 복합재료의 물리적 특성
서광석,박광석,이철호 고려대학교 공학기술연구소 1999 공학논문집 Vol.37 No.1
Physical properties of short glass fiber-reinforced nylon 6,6 and ionomer (Surlyn 9020) composites were studied. While ionomer content was increased from 0 to 30phr, tensile strength and flexural strength were decreased, whereas impact strength had maximum value at 20phr. Permittivity, tans, and volume resistivity had no remarkable difference with the variation of ionomer content, In PEA (Pulsed electroacoustic) experiments, for moisture-free specimens, homocharges were accumulated near electrodes and increased with the increase of ionomer content up to 20phr. It was found that moisture uptake rate of nylon 6,6 was declined due to hydrophobicity of ionomer. For moisture-contained specimens, homocharges were increased with moisture content at first, and then decreased while moisture content saturated. Moisture-ionomer interaction was a major mechanism of homocharge formation.
서광석,이창용,강창균 고려대학교 공학기술연구소 1991 고려대학교 생산기술연구소 생기연논문집 Vol.27 No.1
Electrical conduction characteristics of low density polyethylene with a silicon-oil layer at the surface have been investigated at medium fields ranging from about 75 to 650 ㎸/㎝ over the temperature range of 20 to 100℃. The conduction current of polyethylene increases exponentially with the electric field and gets higher as the temperature increases. The observed conduction behavior was explained in term of the SCLC and tunneling effect. Activation energy ranges from 0.54 to 0.44 eV over the field range of 90∼450 ㎸/㎝ and the charge mobility was estimated from a Child law to be in the order of 10^(-16)∼10^(-14)㎡/V·s. Silicone oil layer modifies the conduction behaviors in polyethylene. Major changes are (1) an increase in conduction currents, (2) a suppression in a rate of change of conduction currents, and (3) a decrease in activation energy.
광섬유 센서를 이용한 절연유의 방전신호 및 감쇄특성 측정
김태영,김상준,남진호,서광석,이수묵 고려대학교 공학기술연구소 1999 공학논문집 Vol.37 No.1
This paper presents the preliminary results on the application of optical fiber sensor(OFS) for the measurements of discharging signal and degradation in insulation oil such as transformer and silicone oil. An OFS system using a Mach-Zehnder interferometry technique was built to detect attenuation of acoustic signal produced by discharging. Simultaneous measurements were made of electrical signal and OFS signal from discharge. It was found that the arcing signal produced by needle-sphere electrode system could be detected by OFS installed in an oil bath. With increasing OFS distance from an arcing spot, the attenuation of acoustic signal became greater. From the results of sound attenuation for various insulation oils, the linear relationship was observed between the attenuation signal and viscosity in log scale. Details of these results are discussed.
( Ju Yeun Lee ),( Yul Hee Kim ),( Nam Joon Yi ),( Hyang Sook Kim ),( Hye Suk Lee ),( Byung Koo Lee ),( Hye Young Kim ),( Young Rok Choi ),( Geun Hong ),( Kwang Woong Lee ),( Yung Suk Suh4 ) 대한간학회 2014 Clinical and Molecular Hepatology(대한간학회지) Vol.20 No.2
Background/Aims: The most commonly used immunosuppressant therapy after liver transplantation (LT) is a combination of tacrolimus and steroid. Basiliximab induction has recently been introduced; however, the most appropriate immunosuppression for hepatocellular carcinoma (HCC) patients after LT is still debated. Methods: Ninety-three LT recipients with HCC who took tacrolimus and steroids as major immunosuppressants were included. Induction with basiliximab was implemented in 43 patients (46.2%). Mycophenolate mofetil (MMF) was added to reduce the tacrolimus dosage (n=28, 30.1%). The 1-year tacrolimus exposure level was 7.2 ± 1.3 ng/mL (mean ± SD). Results: The 1- and 3-year recurrence rates of HCC were 12.9% and 19.4%, respectively. Tacrolimus exposure, cumulative steroid dosages, and MMF dosages had no impact on HCC recurrence. Induction therapy with basiliximab, high alpha fetoprotein (AFP; >400 ng/mL) and protein induced by vitamin K absence/antagonist-II (PIVKA-II; >100 mAU/mL) levels, and microvascular invasion were significant risk factors for 1-year recurrence (P<0.05). High AFP and PIVKA-II levels, and positive 18fluoro-2-deoxy-d-glucose positron-emission tomography findings were significantly associated with 3-year recurrence (P<0.05). Conclusions: Induction therapy with basiliximab, a strong immunosuppressant, may have a negative impact with respect to early HCC recurrence (i.e., within 1 year) in high-risk patients. (Clin Mol Hepatol 2014;20:192-203)
Suh, Kwang-Sik,Lee, Seung-Gwan,Lee, Chang-Kyou,Cho, Kyung-JIn,Chang, Chul-Soo,Kim, Jae-Young 高麗大學校 倂設 保健大學 保健科學硏究所 2002 保健科學論集 Vol.28 No.2
We have investigated the effects of individual soybean isoflavones, genistein (4,5,7-trihydroxyisoflavone) and daidzein (4,7-dihydroxyisoflavone), on tumor necrosis factor-α (TNF-α)-induced apoptosis and the production of local factors in osteoblastic cells. Soybean isoflavones increased DNA synthesis and the number of viable cells. When the cells were treated with TNF-α (10^(-11)M∼10^(-9) M), the number of viable cells was dose-dependently decreased. The decrease in the cell number caused by TNF-α treatment was due to apoptosis, which was manifested by TUNEL and cell death ELISA method. Soybean isoflavones inhibited the apoptosis of osteoblastic cells subjected to TNF-α treatment. It can be suggested that these isoflavones may be involved in maintaining the viability and proliferation of osteoblastic cells. MC3T3-E1 osteoblastic cells secrete IL-6, IL-1ß, NO and PGE₂ constitutively, but at low levels. Soybean isoflavones have no effect on the constitutive production of these local factors. When the cells were treated with TNF-α (10^(-10)M), the production of IL-6 and PGE₂, but not that of IL-1ß and NO, was increased significantly. Treatment with soybean isoflavones (10^(-5)M) in the presence of TNF-α (10^(-10)M) for 48 hours inhibited the production of IL-6 and PGEz, suggesting the antiresorptive action of soy phytoestrogen may be mediated by decrease in these local factors. The findings of this study suggest that the function of osteoblastic cells is promoted by soybean isoflavones, thereby playing an important role in bone remodeling.
SUH, Kwang Sik,NAM, Yeon Ho,AHN, Young Min,KIM, Nam Jae,PARK, Cheol Young,KOH, Gwanpyo,OH, Seungjoon,WOO, Jeong Taek,KIM, Sung Woon,KIM, Jin Woo,KIM, Young Seol WHO COLLABORATING CENTRE FOR TRADITIONAL MEDICINE 2003 東西醫學硏究所 論文集 Vol.2003 No.-
Endothelial cell apoptosis has been postulated as the initial trigger of the progression of progression disease in patients with diabetes mellitus. To investigate the role of Scutellariae radix extract, we examined its effect on the endothelial cell proliferation using the [(3)^H]-thymidine incorporation method. Scutellariae radix extract significantly stimulated endothelial cell proliferation in a dose-dependent manner. We focused on the protective action of Scutellariae radix extract on the endothelial tell apoptosis induced by high glucose concentrations. Determination of endothelial cell apoptosis was performed using DNA gel electrophoresis, terminal deoxynuclotidyl transferase-mediated dUTP nick end-labeling(TUNEL) assay, and an ELISA kit. Exposure of vascular endothelial cell to high glucose (16.7mM) for 72h resulted in a significant increase in apoptosis, compared with the normal glucose concentrations (5.5mM). Scutellariae radix extract inhibited high glucose-induced endothelial cell apoptosis. This result suggests that Scutellariae radix extract may contribute to antiapoptotic action against vascular endothelial cells, resulting in a beneficial effect in preventing diabetes-associated microvascular complications.
( Kwang-woong Lee ),( Suk-won Suh ),( Jaehong Jeong ),( Hyeyoung Kim ),( Nam-joon Yi ),( Kyung-suk Suh Surgery ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1
Aims: In spite of expansion of indication for advanced hepatocellular carcinoma (HCC), the portal vein tumor thrombosis (PVTT) has been accepted as an absolute contraindication for liver transplantation. However, we experienced unexpectedly good prognosis in selected cases with pre-transplant PVTT. In this study, we tried to identify the prognostic factors after living donor liver transplantation (LDLT) for HCC with major PVTT. Methods: Between January 2009 and December 2013, 282 patients underwent living donor LT (LDLT) for HCC at our institution. Among them, 11 patients (3.9%) with major PVTT diagnosed before transplantation were retrospectively reviewed. Results: The duration of follow-up was more than 2 years in all patients. HCC recurrence occurred in 6 patients (54.5%) after LDLT. One-year, 3-year, and 5-year recurrence-free survival was 63.6%, 42.4%, and 42.4%, respectively. One-year, 3-year, and 5-year overall survival was 72.7%, 63.6%, and 63.6%, respectively. Main PV invasion, high value of multiplication of AFP and PIVKA-II (AP score, ≥ 20,000), large original tumor (> 7cm) were significant risk factors for HCC recurrence after LDLT in pre-transplant major PVTT. There was no recurrence in 5 patients with low AP score (< 2,000). Conclusions: If pre-transplant PVTT is not to exceed main PV and AP score is less than 20,000, we can consider LDLT as a curative treatment option. [figure1]