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Yan, Bing Chun,Park, Joon Ha,Kim, Sung Koo,Choi, Jung Hoon,Lee, Choong Hyun,Yoo, Ki-Yeon,Kwon, Young-Geun,Kim, Young-Myeong,Kim, Jong-Dai,Won, Moo-Ho Kluwer Academic/Plenum Publishers 2012 Cellular and molecular neurobiology Vol.32 No.8
<P>In the present study, we investigated neuronal death/damage in the gerbil hippocampal CA1 region (CA1) and compared changes in some trophic factors, such as brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF), in the CA1 between the adult and young gerbils after 5 min of transient cerebral ischemia. Most of pyramidal neurons (89%) were damaged 4 days after ischemia-reperfusion (I-R) in the adult; however, in the young, about 59% of pyramidal neurons were damaged 7 days after I-R. The immunoreactivity and levels of BDNF and VEGF, not GDNF, in the CA1 of the normal young were lower than those in the normal adult. Four days after I-R in the adult group, the immunoreactivity and levels of BDNF and VEGF were distinctively decreased, and the immunoreactivity and level of GDNF were increased. However, in the young group, all of their immunoreactivities and levels were much higher than those in the normal young group. From 7 days after I-R, all the immunoreactivities and levels were apparently decreased compared to those of the normal adult and young. In brief, we confirmed our recent finding: more delayed and less neuronal death occurred in the young following I-R, and we newly found that the immunoreactivities of trophic factors, such as BDNF, GDNF, and VEGF, in the stratum pyramidale of the CA1 in the young gerbil were much higher than those in the adult gerbil 4 days after transient cerebral ischemia.</P>
A Study on Bias Effect on Model Selection Criteria in Graphical Lasso
Young-Geun Choi,Seyoung Jeong,유동현 계명대학교 자연과학연구소 2018 Quantitative Bio-Science Vol.37 No.2
Graphical lasso is one of the most popular methods to estimate a sparse precision matrix, which is an inverse of a covariance matrix. The objective function of graphical lasso imposes an 1 A study on Bias Effect on Model Selection Criteria in Graphical Lasso Young-Geun Choi1, Seyoung Jeong2, Donghyeon Yu2* 1SK Telecom, Seoul 04539, Korea 2Department of Statistics, Inha University, Incheon 22212, Korea (Received Oct 8, 2018; Revised Nov 4, 2018; Accepted Nov 12, 2018) Abstract Graphical lasso is one of the most popular methods to estimate a sparse precision matrix, which is an inverse of a covariance matrix. The objective function of graphical lasso imposes an ℓ-penalty on the (vectorized) precision matrix, where a tuning parameter controls the strength of the penalization. The selection of the tuning parameter is practically and theoretically important since the performance of the estimation depends on an appropriate choice of tuning parameter. While information criteria (e.g. AIC, BIC, or extended BIC) have been widely used, they require an asymptotically unbiased estimator to select optimal tuning parameter. Thus, the biasedness of the ℓ- regularized estimate in the graphical lasso may lead to a suboptimal tuning. In this paper, we propose a two-staged bias-correction procedure for the graphical lasso, where the first stage runs the usual graphical lasso and the second stage reruns the procedure with an additional constraint that zero estimates at the first stage remain zero
김영근 ( Young Geun Kim ) 경남대학교 극동문제연구소 2013 ASIAN PERSPECTIVE Vol.37 No.2
I review the principle of reciprocity in South Korean security policy with regard to North Korea and the United States and analyze how the principle fits with US security policy concerning South Korea. Diffuse reciprocity shaped Korean security policy starting with President Kim Dae-jung`s Sunshine Policy. The Lee Myung-bak government`s hard-line approach increased military tension and economic anxiety on the peninsula. The new South Korean government under Park Geun-hye should devise achievable policy measures rather than place excessive pressure or unrealistic demands on North Korea.
유산균들의 콜레스테를 저하성, 내산성, 내담즙성, 항생제 내성 비교
박소영,고영태,정후길,양진오,정현서,김영배,지근억 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.3
기능성 요구르트의 제조에 사용되는 유산균은 인체에 유익한 생리활성과 우수한 생존능력을 보유하고 있는 것이 바람직하다. 본 연구에서는 다양한 유산균주의 산과 담즙 및 항생제에 대한 내성을 조사하였으며 in vitro에서 콜레스테롤 저하능을 조사하였다. In vitro에서 콜레스테롤 저하능이 우수한 13균주를 선발하여 이들의 동결건조 분말을 고 콜레스테롤 식이의 실험쥐에 투여하였다. 그 결과 8균주는 비 투여구보다 유의적으로 18.3~27.3%의 콜레스테롤 저하능을 나타냈다(P≤0.05). 이들 중에서 Bifidobacterium infantis AM-220, Lactobacillus AM-245, Streptococcus MA-1의 3균주를 이용하여 요구르트를 제조한 후 동결건조 분말을 이용하여 급여실험을 수행한 결과, 총 콜레스테롤과 LDL 함량이 유의적으로 감소하는 것으로 나타났다. For a probiotic yoghurt it is desirable to utilize lactic acid bacteria with a high survival rate and beneficial function to human beings. We have examined a variety of lactic acid bacteria to assess the acid and bile tolerance and antibiotic resistance. In addition, an in vitro culture experiment was performed to evaluate their ability to reduce cholesterol levels in the growth medium. Thirteen strains were selected from in vitro cholesterol assays and fed to Sprague-Dawley rats with a high-cholesterol diet. Among the 13 strains tested, 8 strains were shown to reduce serum cholesterol levels significantly after 24 days of administration in vivo. Rats were fed lyophilized yoghurt powder fermented with a combination of 3 selected strains: Bifidobacterium infantis AM-220, Lactobacillus AM-245, and Streptococcus MA-1. The levels of total cholesterol and low density lipoprotein were significantly lower (p≤0.05) in rats fed the yoghurt powder compared with control group. These studies suggest that yoghurt fermented with appropriately selected lactic acid bacteria may have a anticholesterolemic effect.
강전계하에서 PZT-BYF계의 압전 및 유전특성에 미치는 영향
이영근 한국교통대학교 2014 한국교통대학교 논문집 Vol.49 No.-
The 0.99Pb(Zr0.53Ti0.47)O3-0.01Bi(Y1-xFex)O3 [PZT-BYF(x)] (x=0.0-0.3) piezoelectric ceramics have been synthesized by using a modified conventional solid-state method. The effects of BYF(x) addition on the phase formation, microstructure, and piezoelectric/dielectric properties were evaluated. In addition to these measurements, the piezoelectric voltage constant (g33) and the piezoelectric transduction coefficient (d33×g33) were measured in order to evaluate the essential criteria for an energy-harvesting material. With increasing content of Fe2O3 in the BYF(x) system, the piezoelectric and the dielectric properties were significantly improved. At a sintering temperature of 1,170ºC, the piezoelectric and the dielectric properties of PZT-BYF(x) ceramics showed desirable values; this resulted in a significantly higher transduction coefficient. The compositions of PZT-BYF(0.1), PZT-BYF(0.2), and PZT-BYF(0.3) showed a considerably lower ε33T value, but higher d33 and kp values. Therefore, within the concentration limit of x = 0.1 to 0.3 moles of Fe2O3, the g33 and the d33×g33 values were improved significantly. The maximum transduction coefficient of 20,167×10-15 m2/N was obtained from the composition of PZT-BYF(0.3), while the maximum tip displacement of 7.9㎛ was obtained from MPB composition of PZT-BYF(0.2) under alternative electric field.
김영근 서울시립대학교 부설 서울학연구소 2003 서울학연구 Vol.- No.20
This paper examines different changes taken place in the core and the periphery of Seoul during the Japanese colonial period. It discusses that such spatial characteristics coincide with a typical scene of colonial cities where division of areas according to different racial groups was apparent. Formation of the periphery and the different characters they had compared to the core of the city showed major characteristics of urbanization, especially that of capitalistic urbanization, and such were apparent in urbanization of Keijo. First of all, a city planning which shapes physical appearance of spatial areas differed considerably between the core and the peripheral areas. Therefore, there were great differences not only on the horizontal but also the vertical levels in the core and the periphery of the city; that is, as urbanization progressed, dualistic spatial structures were formed in the core and the periphery of Keijo. While the core was developed under 'the Great Keijo' plan that the Japanese colonial government continuously propagandized, the periphery showed contradictory scenes symbolizing advantages and disadvantages (bright and dark sides) of urbanization. In this regard, study on the differentiation of the core and the periphery areas is necessary not only to realize colonial characteristics of racial differentiation in urban spatial areas but also to understand overall characteristics in colonial urbanization in Seoul. Although studies on Seoul during the colonial era mostly dealt with the central part of the city, more attention needs to be paid on the periphery of the city, especially those outskirts of the old city, considering the importance of historical study on the area. As mentioned in the paper, urbanized during the colonial period, those outskirts areas of Seoul led development of the city after the Liberation in 1945. The city planning and developments taken place in that areas continued to play an important role in urbanization in other areas after the Liberation of Korea.
IO_4-산화전분 변형에 의한 밀 β-Amylase의 안정성 증가
안용근 한국식품영양학회 2000 韓國食品營養學會誌 Vol.13 No.4
과요오드산-산화전분으로 밀 β-amylase(Himaltosin GL. 일본한큐바이오사)를 변형시켜서 인공당단백질을 만들었다. pH 8.0에서 변형한 효소는 비변형효소의 96%. pH 9.7에서 변형한 효소는 17%의 활성이 남았다. 60℃에서의 열안정성은 α-cyclodextrin (α-CD)존재 시에 변형하여 α-CD 존재시에 분석한 효소는 10분 뒤에 비활성의 8%가 남은 반면 변형하지 않은 효소는 5% 밖에 남지 않았다. pH안정성은 변형시켜서 α-CD존재 하에 분석한 효소가 가장 높아서 pH 2∼5와 6∼12에서 안정성이 매우 증가하였다. HPLC 분석 결과 효소는 하나의 피크를 나타냈으며 변형시킨 것은 당결합으로 분자량이 커져서 유출시간이 약간 빨라졌다. The stabilization of wheat β-amylase(Himaltosin GL, Hankyu-Bio) was attained by modification with periodate-oxidized soluble starch. The specific activities of modified enzyme at pH 9.7 and pH 8.0 were 17% and 96%, respectively, compared with that of native enzyme. The pH stability of modified enzyme was increased at pH 2∼5 and 6∼12 in the presence of α-cyclodextrin(α-CD) compared with that of native enzyme, and optimum pH of the enzyme was changed from pH 5.0 to pH 7.0 by the modification. Thermal stability of the modified enzyme was increased. After treatment at 60℃ for 10min, the activity remained 8% for the enzyme modified at pH 8.0 in the presence of α-CD and tested in the presence of α-CD, 5% for the native enzyme. The native enzyme and modified enzyme showed one peak in HPLC. The molecular weight of the modified enzyme was slightly increased in HPLC analysis.
도근영,이한석,고성철,현번수,유종수 韓國海洋大學校 附設 海洋科學技術硏究所 2002 硏究論文集 Vol.11 No.2
워트프런트는 도심 및 내륙지역과는 다른 독특한 기후특성을 가지고 있으며 이를 고려하지 않고 개발할 경우 시설물의 하자발생, 에너지 및 유지관리비용의 상승을 초래하게 됨은 물론 배후지, 도시기후에 악영향을 미치게 된다. 본 연구는 부산지역의 10개 기상관측지점을 해안선에서 거리에 따라 워터프런트 및 내륙지역으로 분류하고 5년간의 기상데이터를 이용하여 워터프런트의 기후특성에 대해 검토한다. 또한 원터프런트지역임에도 내륙지역과 유사한 기후특성이 나타나고 있는 대연지점을 대상으로 기후특성변화의 원인에 대해 검토한다. The waterfront has distinct climate characteristics different from urban or inland area. These may create not only the rise of energy and maintenance costs for facilities located at waterfront areas, but also negative effects on the climate of the nearby inland area, unless these are treated with particular care. For the present study, the climate characteristics of waterfront were examined with climate data of 10 observation points carefully selected in Busan area. Each weather observation point was classified into either waterfront area of inland area, based on the distance from the coastal line. Special considerations were given to the climate data gathered at the Dae-Yeon weather station because it shows the climate characteristics similar to those of inland area although it is located very near the waterfront area. Results indicates that this peculiar climate condition attributes, at least in part, to the reclamation of frontal coastal area.