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Lee, Na Ri,Shin, Hee Keun,Choi, Sung Ho,Kim, Ju Bum,Lim, Jae Won,Park, Doh Young,Mok, Hyung Soo The Korean Society for Railway 2015 International Journal of Railway Vol.8 No.1
Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.
Sang Mok Lee,Jin Hak Lee 대한검안학회 2007 Annals of optometry and contact lens Vol.6 No.1
Purpose: To compare the time of posterior capsule opacification (PCO) occurrence in the first eye and the second eye in bilaterally PC-IOL implanted patients. Methods: This retrospective study comprised of 332 eyes of 166 patients who received phacoemulsification and PC-IOL implantation due to cataract in both eyes from January, 1993 to December, 1998 by one surgeon. Time interval between the surgery and the PCO occurrence and the follow up period was reviewed. Kaplan-Meier method and Mann-Whitney U test were used for statistical analysis. Results: PCO occurred in 12 patients in the first eye only, in 9 patients in the second eye only, and in 13 patients in both eyes. Twenty-five percent PCO occurrence time for the first eye was 51.1 months and for the second eye was 34.9 months using Kaplan Meier survival analysis. Overall PCO occurrence rates were not significantly different between the two groups using log rank test (p=0.15). But in the younger age group(under 60 years old), PCO occurrence time was significantly shorter after the second eyes surgery compared with the first eyes surgery using Mann-Whitney U test (p=0.038). Conclusions: In bilaterally PC-IOL implanted eyes, overall PCO occurrence rates were not significantly ifferent. However, PCO occurs earlier in the second eyes than in the first eyes in the younger age group.
LEE, Jae Sung,LEE, Jong Suk,YOON, Jae-Don,BEAK, Sung-Mok,BOSIRE, Kefa O.,LEE, Yong-Soo,KIM, Jung-Ae 德成女子大學校 藥學硏究所 2004 藥學論文誌 Vol.15 No.1
Over the past several years, research efforts have been directed both at economically producing valuable substances from the wood biomass and at producing lignolytic enzymes at a lower cost. In the present study, we found that Phellinus igniaruas, the basidiomycetes, secreted lignin peroxidase as a main lignolytic enzyme, which was detected maximum activity at 16th day of culture and showed 37 kDa of molecular mass in identification by activity assay and purification by anion-exchange chromatography. The Phellinus igniarius-derived lignin peroxidase hydrolyzed steam-exploded wood (Quercus ntongolica) powder into small molecules showing cytotoxicity against cancer cells (HepG2 hepatoma, SK-N-SH neuroblastoma, B16 melanoma, MBT-2 bladder cancer). ha addition, the enzyme hydrolysates of lignins (ELg) that were extracted from the steam-exploded oak showed more potent cytotoxic effects on the cancer cells than the enzyme hydrolysates of wood biomass (EWp). indicating that the cytotoxic effect of EWp may be due to the enzyme-degraded products of lignin among the lignocellulosics. Furthermore, the cytotoxic effect of ELg on Chang, normal liver cells, was much less potent than that of ELg on HepG2 and B16 cancer cells, indicating that the cytotoxic effect of ELg may be specific for cancer cells. The present results suggest that Phellinus igniarius may be a useful resource for the large-scale production of lignin peroxidase and that the lignin peroxidase may be applied for the generation of valuable biodegradation products from wood lignocellulosics for medical use.
Lee, Hye-Sung,Choi, Jun-Hyeok,Kim, Young-Eon,Kim, In-Ho,Kim, Byoung-Mok,Lee, Chang-Ho The Korean Society of Food Science and Nutrition 2013 Preventive Nutrition and Food Science Vol.18 No.3
The purpose of this study was to investigate the effects of the ethanol extract of Cynanchum wilfordii (ECW) on the blood lipid profile of hypercholesterolemic rats. Thirty 7-week-old male Sprague-Dawley rats were allowed free access to either a normal diet (AIN-93 diet), or 1% high-cholesterol diet with or without 0.5% or 1% ECW for 5 weeks. After sacrifice, the rat serum lipid profile was analyzed. The diets containing ECW decreased body weight gains compared to the normal diet. Serum HDL-cholesterol levels of ECW-fed groups were significantly increased in the hypercholesterolemic groups and normal groups (P<0.05). When 1% ECW was fed to the normal group, total cholesterol level was increased. Moreover, treatment of ECW in hypercholesterolemic groups yielded a dose-dependent and highly significant decrease in the atherogenic index as compared to the control. These results suggest that intake of Cynanchum wilfordii may help reduce the risks of hypercholesterolemia by increasing blood HDL-cholesterol and lowering the atherogenic index.
Lee, Yong Soo,Jin, Da-Qing,Beak, Sung-Mok,Lee, Eung-Seok,Kim, Jung-Ae 德成女子大學校 藥學硏究所 2003 藥學論文誌 Vol.14 No.1
Premature aging of the skin (photoaging) is a well-documented consequence of exposure to ultraviolet-A (UVA). Enhanced generation of reactive oxygen species and induction of matrix metalloproteinases (MMPs) appear to be the most important components of UVA-modulated signal transduction pathways, ultimately leading to photoaging. In this study, we investigated the effects of asiatic acid and ursolic acid, triterpene compounds, on the UVA-modulated signaling pathways, using HaCaT human keratinocytes as a model cellular system. In the cells, we confirmed that UVA irradiation induced oxidative stress and increased the expression of MMP-2. Asiatic acid and ursolic acid significantly reduced the UVA-induced activation and expression of MMP-2. In addition, UVA-induced enhanced expression of p53, a hallmark of UV-induced DNA damage and cell death, was also significantly inhibited by pretreatment with asiatic acid or ursolic acid. Taken together, these results suggest that asiatic acid and ursolic acid may be an effective inhibitor of UVA-modulated signal transduction patyways in human skin cells. These results further suggest that these agents may be useful in the prevention of UVA-induced photoaging.