http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
김청미,백재승,이상호 韓國受精卵移植學會 1995 한국동물생명공학회지 Vol.10 No.3
Frozen storage of the oocytes has been used in a few mammalian species including mouse, hamster, human and cattle. However, frozen4hawed oocvtes show different sperm penetration on the levels of the zona pellucida and the plasma memhrane when compared with fresh oocytes. To elucidate biological changes occurring during freezing and thawing, we examined the kinetics of sperm penetration into frozen-thawed hamster oocytes. Oocytes obtained from superovulated female golden hamsters were frozen-thawed in an autofreezer according to an established method. Fresh and frozen4hawed oocytes were fertilized in vitro with capacitated hamster spermatozoa after removing the zona pellucida. The oocytes were examined at 1, 2, 3 and 6 h postinsemination. Sperm penetration found to be 1 h delayed in frozen-thawed oocytes. Other parameters such as degree of polyspermy and decondensing sperm heads were not affected by freezing and thawing. The results suggest that freezing and thawing may cause changes in the egg membrane surface and subsequently which leads to delay in the sperm-egg fusion.
중국의 해외직접투자에 현지국과의 정치외교관계 및 제도적 거리가 미치는 영향에 관한 연구
김청미,SHEN JIA 현대중국학회 2019 現代中國硏究 Vol.21 No.3
Since the mid-2000s, the surge in overseas direct investment by Chinese companies has drawn widely attention, but related studies have mostly focused on economic factors. However, China’s overseas direct investment has a strong government-led nature, which makes it hard to explain simply by economic factors. This study is aimed at identifying the role of political relations with local countries. Based on data from 112 countries from 2007 to 2016, the effect of political and diplomatic relations and institutional distance with local countries on direct investment in foreign countries was analyzed through the panel data technique. According to the analysis results, it was possible to statistically confirm that friendly political & diplomatic relations with local countries have a positive effect in promoting direct overseas investment by China. In addition, institutional differences between the home country and the local country could raise the problem of increased management costs, indicating that there existed a negative correlation with China’s overseas direct investment. However, the more friendly relations with local countries are, the weaker the negative impact institutional distance has on direct investment abroad. In other words, the adjustment effect of friendly bilateral relations has been confirmed, and this can be seen as one of the important facilitators for Chinese companies to advance into countries with large institutional differences. This study has academic and policy implications by serving as the first button to link economic and political perspectives when looking at direct investment in China. 2000년대 중반부터 중국기업의 해외직접투자의 급증세가 세간의 주목을 받고 있지만 이를 둘러싼 연구들은 대부분 경제적 요소에 초점을 두고있다. 그러나 중국의 해외직접투자는 정부주도적 성격이 강해 단순히 경제적 요인만으로 설명하기 어려운 부분이 많다. 본 연구는 현지국과의 정치관계의 역할을 규명하는 데 목적이 있다. 2007년부터 2016년까지 중국해외직접투자가 이뤄진 112개 국가의 자료를 바탕으로 현지국과의 정치ㆍ 외교 관계와 제도적 거리가 해외직접투자에 미치는 영향을 패널데이터 기법으로 실증 분석하였다. 분석결과에 따르면 먼저 현지국과의 우호적 정치외교관계가 중국의 해외직접투자를 촉진하는 긍정적인 효과가 있음을통계적으로 확인할 수 있었다. 또한, 본국과 현지국 간의 제도적 차이는불확실성 등에 따른 경영비용증가 문제를 불러일으킬 수 있어 중국기업의해외직접투자와 부(-)의 상관관계가 존재한 것을 알 수 있었다. 그러나 현지국과의 관계가 우호적일수록 제도적 거리가 해외직접투자에 미치는 부정적 영향이 약화되는 것으로 나타났다. 즉 우호적 양국관계의 조절효과가 확인되었고, 이는 중국기업을 제도적 차이가 큰 국가로 진출하게 하는중요한 촉진요인 중 하나로 볼 수 있다. 본 연구는 중국 해외직접투자를바라볼 때 경제적 시각과 정치외교적 관점 연결하는 첫 단추 역할을 함으로써 학문적ㆍ정책적 시사점을 지니고 있다.
Ca₂SiO₄ : La 열형광체 제작과 물리적 특성에 관한 연구
김청미(Choungmi Kim),서미경(Mikyong Seo) 한국방사선학회 2010 한국방사선학회 논문지 Vol.4 No.4
Ca₂SiO₄를 모체로 한 열형광체에도 활성제로 La를 0.1 wt.%, 0.3 wt.%, 0.5 wt.%, 1.0 wt.%의 농도로 첨가하여 1000℃의 질소 분위기의 전기로에서 90분 동안 소결한 후 입자의 크기를 100 ㎛로 일정하게 선별한 후 측정에 사용하였다. 저에너지 X-선을 조사한 후 측정한 경우 0.1 wt.%에서 상대적으로 열형광 강도가 크게 나타났다. peak shape 법으로 구한 활성화 에너지는 0.434~0.516 eV이며, 주파수 인자는 0.5 ~ 0.56으로 2차 발광이었다. 자외선을 조사한 후 측정한 경우 0.3 wt.%에서 상대적인 열형광 강도가 크게 나타났고, 활성화 에너지는 0.415~0.477 eV이며, 주파수 인자는 0.5 ~ 0.53 으로 2차 발광이었다. 저에너지 방사선에 대한 방사선량과 열형광 강도는 선형적임을 나타내어 열형광선량계로서 좋은 특성을 나타내고 있다. 본 연구에서 제작한 CaB₄O₇, Ca₂SiO₄ 열형광체는 저에너지 영역의 방사선에 대하여 우수한 열형광 특성을 가짐을 알 수 있었고, 향후 선량계의 제작에 좋은 물질이 될 것으로 생각한다. The Ca₂SiO₄ phosphors doped by La with 0.1 wt%, 0.3 wt%, 0.5 wt%, and 1.0 wt% concentration were prepared by sintering at 1000℃ for 90 minutes in N2 atmosphere. The phosphors were ground in powdered form and were grouped in 100 ㎛ size, then the samples had been exposed to low energy X-ray and UV light. The TL glow curves were measured by heating the phosphors at 10℃/s rate. There was no significantly meaningful correlation between the TL intensity and the doping level. The intensities of the TL peak measured from X-ray irradiated samples doped with 0.1 wt% were relatively strong. The activation energy and the frequency factor were 0.434 ~ 0.516 eV and 0.5 ~ 0.56, respectively. The intensities of the TL peak measured from UV irradiated samples doped with 0.3 wt% were relatively strong. The activation energy and frequency factor were 0.415 ~ 0.477 eV and 0.5 ~ 0.53, respectively. The TL process were found to be the 2nd order for both X-ray and UV irradiation. The TL intensity was increased linearly with the increase of the radiation dose. In summary, the Ca₂SiO₄ phosphors developed in this study showed good TL characteristics at low energy X-ray and UV light. We believe they will be used as TLDs in near future for personal and environmental radiation detection dosimetry.