최근 전 세계적인 원자력 수요 급증으로 민감 기술의 확산에 대한 우려가 커지고 있다. 원자력 수요 증가에 대처하면서 핵비확산체제를 강화하기 위해，다수의 ‘핵연료주기 다자화’ 방안이 제안되었다. ‘핵연료주기 다자화’ 방안이 실현될 경우，우리나라에 영향을 미칠 것으로 예상된다. 따라서 본 논문에서는 ‘핵연료주기 다자화’ 움직임에 대해 우리나라의 적절한 대응책 마련에 도움을 주기 위해，12가지 기존의 ‘핵연료주기 다자화 방안’ 을 검토하고，우리나라에 미칠 잠재적 영향을 평가하였다.

외연적 유한요소법은 벡터처리에 적합한 구조를 가지고 있어 벡터컴퓨터를 이용하면 기존의 스칼라 컴퓨터에서보다 휠씬 빠르게 해석을 수행할 수 있다. 본 논문에서는 memory-to-memory방식의 벡터컴퓨터에서의 외연적 유한요소법의 효율적인 벡터화 방법을 제시하였다. 먼저 벡터컴퓨터의 구조적 특성과 무관하게 적용될 수 있는 일반적인 벡터화 기법을 고찰한 후 memory-to-memory방식의 벡터컴퓨터에 적합한 벡터화 기법을 개발하였다. 개발된 벡터화 기법의 유용성을 확인하기 위해 외연적 유한요소 프로그램인 DYNA3D를 memory-to-memory방식의 벡터컴퓨터인 HDS AS/XL V50에 이식한 결과 스칼라에 비해 2.4배 이상의 성능 향상을 얻을 수 있었다.

This paper finds some stylized facts about executive pay in South Korea. Using aggregate data of the listed companies since 2002, we find that 1) the director’s remuneration has risen faster than the employee compensation, thus, the pay ratio of executive and employee has escalated from 3.0 to 4.5; 2) the executive compensation for large business group fluctuates more widely than that for small and medium enterprises does, hence the pay ratio for large firms changes widely too; 3) the median pay ratio has not grown monotonically but it rather rises to remain still around year 2011, which is accounted for mostly by small and medium enterprises. New information on executive compensation by compulsory disclosure starting from 2013 made further analysis of CEO compensation attainable. Based on the conventional regression analysis for 2013-2017, we find that 1) the elasticity of CEO pay with respect to firm value is about 0.18; 2) the volatility of stock return is negatively related to CEO pay; 3) contemporaneous stock return is positively associated with the pay; 4) there is insufficient evidence that large business groups pay their CEOs more than small and medium enterprises do. These results are robust under various model specifications.

Background : This study was conducted to determine the optimal ginseng greenhouse shading material for minimizing heat injury and maximizing the yield of ginseng plants in an effort to develop a stable ginseng cultivation technology and contribute to popularizing ginseng greenhouse farming. Methods and Results : Three different types of greenhouse shading material were used: polyethylene (PE) film + black screen (95%), light scattering film + black screen (75%), and blue-white vinyl. Important experimental details were implemented in accordance with the Analysis Standard of Agricultural Test and Research set out by the Rural Development Administration. The average greenhouse temperature for the period of May through October was 20.0℃ under the PE film + black screen, 20.2℃under the light scattering film + black screen, and 19.7℃ under the blue/white vinyl. High average photosynthesis rates of ginseng plants were demonstrated by light scattering film+black screen (2.35 μmole CO2/㎡/s) and blue-white vinyl (2.38 μmole CO2/㎡/s), with the PE film + black screen showing a considerably lower photosynthesis rate (1.55 μmole CO2/㎡/s). Heat injury occurred in 0.3%, 10%, and 0.1% of the plants grown under the PE film + black screen, light scattering film + black screen, and blue-white vinyl, respectively. As for the roots, the blue-white vinyl outperformed the other shading materials in root length (25.7 ㎝), taproot length (5.9 ㎝), and the number of fine roots (23.2). The blue-hite vinyl also yielded the greatest root fresh weight (30.2 g), followed by the light scattering film + black screen (29.1 g), with the PE + black screen yielding by far inferior average weight (22.0 g). The highest crude saponin content was yielded by the light scattering film+black screen (16.61 ㎎/g), followed by blue-white vinyl (11.36 ㎎/g) and PE + black screen (11.0 ㎎/g). Conclusion : Comparing the effects of three different shading materials on greenhouse-cultivated 3-year-old ginseng plants, the blue/white vinyl outperformed two other shading materials in most of the growth characteristics, whereas the and the light scattering film + black screen yielded the highest ginsenoside content.

Undomesticated soybeans (Glycine soja) are an important source of genetic variation for introducing useful traits to domesticated soybeans (Glycine max). Although Korea is known as the origin of the soybean, a little is known about genetic diversity and structure analysis of G.soja. The objectives of this study were to investigate the genetic diversity and the structure analysis of wild soybeans, and to construct a core collection of G. soja accessions in Korea. To evaluate the genetic diversity and structure analysis of G.soja, we analyzed allelic profiles at 21 SSR loci of 1028 accessions using POWERMARKER V3.25. These markers generated a total of 581 alleles over all loci. The number of alleles per locus ranged from 21 to 40, with a mean of 28 alleles per locus and a mean gene diversity of 0.886 in this accessions tested. Polymorphic information content value ranged from 0.737 to 0.946, with an average of 0.877. Using STRUCTURE V2.34, wild soybean originated from Korea was divided into two distinct populations, largely corresponding to two geographic regions. Population 1 consisted of eight sub-groups corresponds to mountains; population 2 to entire regions in Korea. Based on theses 21 SSR markers, a core collection development was performed by POWERCORE V1.0. A G. soja core collection consisted of 148 accessions which were established from 1028 accessions in Korea. Most accessions of the core collection were belonged to population 2 and only four were belonged to population 1. These results of this study would provide valuable information for future breeding programs using the G. soja core collection.

Human embryonic stem cells (hESCs) are promising cell source because of their unique self-renewal and pluripotency. Although hESC-derived cardiac cells are currently generated worldwide, cryopreservation of these cells is still limited due to low rate of post-thaw survival. Cryopreservation of hESC-derived cardiac cells is critical in that their long-term storage can accelerate their use in regenerative medicine. However, to date, there are few reports on efficient cryopreservation and post-thaw survival of hESC-derived cardiac cells. In this study, we evaluated the effects of ginsenoside, which is known to improve survival of rat embryonic cardiomyocytes against myocardial ischemia injury in diabetic rats (Wu et al., 2011), on the survival of hESC-derived cardiac cells after thawing. We induced differentiation into cardiac cells using our previously reported method (Kim et al., 2011). Differentiated, pre-beating stage cardiac cells were cryopreserved using either mass cryopreservation or vitrification. To evaluate the effects of ginsenoside (Re, Rb), we compared three sets: pre- and post-thaw treatment, pre- or post-thaw treatment only. The survival of post-thaw cardiac cells were evaluated using Trypan-blue and Annexin V staining. In addition, the three groups were treated with ROCK inhibitor Y-27632, and compared with non-treatment groups. The effect of ginsenoside was significant in post-thaw treatment group, i.e, thawed cells expressed cardiac specific genes and showed specific functionality such as spontaneous beating. Taken together, we demonstrated favorable effects of ginsenoside on the survival of hESC-derived cardiac cells after cryopreservation and thawing. These results suggest a possible application of well-known cardioprotectant ginsenoside in cell-based tissue engineering using hESC-derived cardiac cells.

“Younbaek”, a new noodle making wheat cultivar, was developed from the cross between “Keumkang” with white grain color and “Tapdongmil” by the Honam Agricultural Research Institute(HARI), National Institute of Crop Science (NICS), RDA, Korea in 2005. Amon

“Jokyoung”, a new bread making wheat cultivar, was developed from the cross between “Seri 82”, a hard white wheat from CIMMYT, Mexico and “Keumkang”, a hard white wheat with high milling rate and early maturing from Korea by National Institute of Crop Sci

Three different male-sterile cytoplasmic lines and their common maintainer 'Zhenshan 97B' and two elite restorer lines were used to study cytoplasmic effects on agronomic trait manifestation per se under different nitrogen supply levels. The result showed that cytoplasmic effects could be modified by nitrogen environments. The cytoplasmic effect on grain yield under 150 kg N/ha varied depending on crosses, while it was significantly negative in most crosses under both 60 and 330 kg N/ha. The correlation and path-coefficient analyses suggested that it was expected to improve cytoplasmic effects through reducing maximum tillers and increasing the percentage of productive tillers, leading to increased productive tillers and higher yield in hybrid rice by the aid of cultural practice and genetic transformation. This study also revealed that the same cytoplasm in different combinations had differential effect under the same nitrogen environment, indicating that cytoplasmic effect was produced by interaction of nuclear genes with cytoplasm rather than cytoplasm per se. These results indicated the usefulness of evaluating diverse cytoplasmic sources in various nuclear genotypes bred for hybrid rice breeding program. The finding also suggested that negative cytoplasmic effect could be effectively overcome by elite restorer lines through the interaction of nuclear genes with female cytoplasm.

본 연구는 잡종강세를 나타내는 두 조합의 벼 일대 잡종 품종, Shanyou 63, Teyou 53과 inbred계인 밀양 23호 등을 공시하여 벼의 잡종강세 발현기작을 규명코자 실시되었으며, 수행 후 얻어낸 결과를 요약하면 다음과 같다. 1. 종자 단백질 분석을 통해, 잡종강세 발현의 유전적인 특성들이 부분적으로 모본으로 부터 유전된다는 사실을 규명하였다. 2. Hybrid계 벼는 inbred계보다 배아의 크기가 크고 α -amylase 활성 및 chlorophyll함량이 높게 나타났다. 이러한 특성들은 분얼능력, 특히 수량에 밀접한 영향을 끼치는 하부절간의 분얼수와도 관계가 있었으며, Shanyou 63의 경우 다른 inbred계에 비해 60~70%나 분얼력이 높았다. 3. 인위적으로 GA3 0.02 ppm을 처리한 후 α -amylase활성 측정시, hybrid계에는 영향을 미치지 못하였으나 밀양 23은 무처리보다 높은 활성을 나타내었다. 이와 같은 결과는, hybrid계 벼의 종자내에는 이미 충분한 GA를 함유하고 있으며 이것이 초기활력과 관계있는 것으로 추정된다. 4. Cytochrome c oxidase의 활성은 inbred계 보다 hybrid rice에서 2.7~5.5배나 높게 나타났으며, 따라서 hybrid계 벼의 대사작용이 매우 높았다.