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연마필름을 이용한 내면 수퍼피니싱의 연마조건에 관한 기초 연구
신오철,정수용,정성용 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-
Recently, Along with the increasing demands for ultraprecision processing parts and polishing in inner surface of cylinder, a variety of studies which can be realized in processing of high quality by development of polishing system for ultraprecision polishing is actively processing in recent decades. Therefore, in this study, we developed polishing device in inner surface of cylinder using abrasive film and a studied on the basic polishing characteristic. According to both particle size of polishing film and backing film thickness, we experimented on the polishing characteristic and measured surface roughness. From this result, In the case of SM45C, if abrasive particles are rough and backing film is thick, the optimal polishing time shows a tendency to decrease. Also, we obtained high-efficient surface roughness.
Memory Enhancing and Neuroprotective Effects of Selected Ginsenosides
Sao Hai Ying,Zhang Jing,Yeo Soo Jeong,Myung Chang Seon,Kim Hyang Mi,Kim Jong Moon,Park Jeong Hill,Cho Jung Sook,Kang Jong Seong The Pharmaceutical Society of Korea 2005 Archives of Pharmacal Research Vol.28 No.3
The effects of ginsenosides Rg$_3$(R) , Rg$_3$(S) and Rg$_5$/Rk$_1$ (a mixture of Rg$_5$ and Rk$_1$ 1:1, w/w), which are components isolated from processed Panax ginseng C.A. Meyer (Araliaceae), on memory dysfunction were examined in mice using a passive avoidance test. The ginsenosides Rg3(R), Rg3(S) or Rg$_5$/Rk$_1$, when orally administered for 4 days, significantly ameliorated the memory impairment induced by the single oral administration of ethanol. The memory impairment induced by the intraperitoneal injection of scopolamine was also significantly recovered by ginsenosides Rg3(S) and Rg$_5$/Rk$_1$. Among the three ginsenosides tested in this study, Rg$_5$/Rk$_1$ enhanced the memory function of mice most effectively in both the ethanoland scopolamine-induced amnesia models. Moreover, the latency period of the Rg$_5$/Rk$_1$treated mice was 1.2 times longer than that of the control (no amnesia) group in both models, implying that Rg$_5$/Rk$_1$ may also exert beneficial effects in the normal brain. We also evaluated the effects of these ginsenosides on the excitotoxic and oxidative stress-induced neuronal cell damage in primary cultured rat cortical cells. The excitotoxicity induced by glutamate or Nmethyl-D-aspartate (NMDA) was dramatically inhibited by the three ginsenosides. Rg$_3$(S) and Rg$_5$/Rk$_1$ exhibited a more potent inhibition of excitotoxicity than did Rg$_3$(R). In contrast, these ginsenosides were all ineffective against the H$_2$O$_2$- or xanthine/xanthine oxidase-induced oxidative neuronal damage. Taken together, these results indicate that ginsenosides Rg$_3$(S) and Rg$_5$/Rk$_1$ significantly reversed the memory dysfunction induced by ethanol or scopolamine, and their neuroprotective actions against excitotoxicity may be attributed to their memory enhancing effects.
Gonadal Sex Differentiation of Hatchery-Reared Longtooth Grouper (Epinephelus bruneus)
Sao Pham Ngoc,Hur Sang-Woo,Lee Chi-Hoon,Lee Young-Don 한국발생생물학회 2012 발생과 생식 Vol.16 No.3
For the gonadal sex management of younger longtooth grouper (Epinephelus bruneus), this work investigated the timing and histological process of ovary differentiation and oocyte development of longtooth grouper larvae and juvenile. Specimens (from 1 to 365 DAH) were collected for gonadal histological study from June 2008 to August 2009. Rearing water temperature was ranged from 20 to . The primordial germ cells could be observed from 10 to 15 DAH, while undifferentiated gonad occurs from 20 to 50 DAH in longtooth grouper. The initial ovarian phase was 60 to 110 DAH with the formation of ovarian cavity and the increased in size of gonad. The ovarian phase started at 140 DAH with appearance of oogonia. The gonad at 365 DAH appeared to have full of oogonia and primary growth stage oocyte. Formation of ovarian cavity indicates that the ovarian differentiation beginning at 60 DAH in longtooth grouper. The gonads in longtooth grouper differentiated directly into ovaries in all fish examined.
Childbearing Trends among Older Koreans
In Sao Lee 한국노인복지학회 2002 International Journal of Welfare for the Aged Vol.7 No.-
In this study, differences of childbearing trends by socio-demographic factors were examined among older Koreans aged 60 or more. The results are drawn as follows; Impacts of ① residence, ② age, and ③ family extension period on the number of children are significant. The average number of children is 4.65 for rural elderly, which is significantly larger than that of the urban elders(p <.05). The number is significantly smaller for younger elders than the older group(p <.01); the mean value is only 4.09 for those aged 60-69, while 26% greater(5.15) for those aged 80 or more. There are some significant differences by ① the number of generations living together and ② education found in male rate among children. The average male rates are 0.53 for one generation(living elderly only) and 0.57 for three generations(living with children & grandchildren), all of which are significantly higher than that of two-generations(p <.05). The male rate for those of middle school graduate or less is 0.55, while the rate for high school or above is only 0.46, indicating that the less educated they are, the more sons they have(p <.05). Overall in this study, it is proposed that elderly welfare policies focus on providing more formal home help services for those having few supportive children