Untersuchungen zur interspezifischen Kompatibilitat und Biosystematik bei der Gattung Pelargonium

Yu, Sun-Nam 1985 국내석사

Research on Wheat Industry in China

Sun, Yu-Cong 강원대학교 대학원 2022 국내박사

As one of the three major food crops in China, wheat production plays an important role in people's life and industrial development. China is not only the world's largest consumer of buying products, but also a world wheat trading country. China's wheat production area and output account for about 25% and 22% of the total grain, which is of great significance to China's food security. However, China's wheat production has the characteristics of high input, high yield, and low income. The low quality of wheat production in some regions, large trade deficit, and excessive concentration of import sources also trouble the development of China's wheat industry. This study analyzes the wheat industry from three aspects: wheat production efficiency, the effect of minimum purchase price policy, and wheat import factors. Firstly, the DEA-Malmquist model was used to calculate and analyze the wheat total factor productivity (TFP) of 12 major wheat-producing provinces from 2005 to 2019, and data were obtained from "National Farm Product Cost-benefit Survey", and the diff-GMM estimation was further used to explore the influencing factors and data were obtained from "China Statistical Yearbook", "Rural Statistical Yearbook of China" and "Transport Yearbook". The results showed that from 2005 to 2019, China's wheat total factor productivity showed a declining trend and increased at an average annual rate of -1.5%. From the influence factors of wheat production efficiency, total mechanical power and urbanization have significant positive impacts on the TFP of wheat, while government expenditures for agriculture, forestry and water resources, and industrialization have significant negative effects on wheat TFP. However, the rural road density has no significant effect on the TFP of wheat. Secondly, the objective of the implementation of the minimum purchase price policy for wheat is to promote the increase of wheat production. According to statistics, wheat production increased from 108.466 million tons in 2006 to 133.596 million tons in 2019 after the implementation of the minimum purchase price policy. However, how much did the implementation of the minimum purchase price policy contribute to wheat production increase? Based on the panel data of 15 major wheat-producing provinces in China from 1998 to 2019, this study adopted the propensity score matching and difference-in-differences methods (PSM-DID) to conduct a robustness test and empirical test on the impact of China's minimum purchase price policy on wheat production. The results show that the implementation of wheat's minimum purchase price policy can significantly affect wheat production, and the implementation of wheat minimum purchase price policy can increase wheat production by 76.89% when other factors affecting wheat production remain unchanged. Thirdly, the import trade pattern of wheat was studied and analyzed, and the gravity model of trade is selected and Poisson Pseudo-Maximum Likelihood (PPML) estimator is used to conduct an empirical analysis on the influencing factors of wheat import trade. From 2010 to 2020, China gradually formed an import pattern dominated by Australia and Canada, supplemented by the United States, France, and Kazakhstan. Mexico, Argentina, and other countries gradually withdrew from wheat trade with China. Among the factors affecting China's wheat import trade, China's per capita GDP and total imports, geographical distance, current GDP of exporting countries, and last year's wheat output have a significant impact on China's wheat import. In addition, climate factors also have a significant impact on China's wheat imports. To promote the sustainable improvement of wheat productivity, the future development of the wheat industry should focus on the transformation of agricultural development mode, human resources investment, and encourage the industry sector to nurture agriculture. China keeps maintaining a minimum purchase price policy to ensure stable wheat production. But at the same time, the government should set up supporting facilities to improve the policy, such as the implementation of a wheat planting income insurance system, the establishment of a spot market, and improve the futures market. China can take full advantage of its economic cooperation with countries along the Belt and Road and further expand its cooperation with the wheat trade of Turkey, Israel, Kazakhstan, the Russian Federation, and other countries located on the Silk Road. And produce high-quality wheat, expand wheat export, a link trade deficit. Make good use of domestic and foreign wheat markets in a balanced way to ensure China's food security.

Development of hydrogel combined scaffolds for bone tissue engineering

Yu, Hye-Sun Dankook university 2014 국내박사

Scaffolds play central roles in cultivation of stem cells and driving their differentiation into target tissues including bone. In this study, we developed scaffolds for tissue engineering of bone with emphasis on the effective cultivation of stem cells and their stimulation to osteogenesis. For this, collagen-based hydrogels were combined with the 3-dimensionally constructed scaffolds made of either bioactive ceramics or, degradable polymers. Furthermore, a novel hybrid composition of silica / collagen was developed to exert improved physico-chemical, mechanical and biological properties. The first study, the calcium phosphate (CaP) ceramic scaffolds were combined with collagen gel encapsulating rat bone marrow mesenchymal stem cell (rMSC). The rMSCs in the gel-combined CaP scaffolds showed higher cell loading and proliferation activity compared with those seeded directly onto the CaP scaffold. Moreover, the rMSCs cultured in the gel-combined CaP scaffolds showed up-regulation of series of osteogenic markers at the gene and protein level, and the deposition of cellular mineralized products. Results demonstrated the effectiveness of the 3D gel culture of stem cells for bone tissue engineering. The second study was undertaken to develop collagen gel combined degradable polymer poly-(caprolactone) and further to apply flow perfusion culture system, aiming at promoting cell proliferation and osteogenic differentiation. The rMSCs cultured in this combined scaffold under flow perfusion proliferated at significantly higher levels than those cultured in the same scaffold under static conditions. The expression of bone-related genes and the osteogenic marker proteins was substantially improved by the flow perfusion culture, implying the impacts of dynamic flow perfusion culture for bone tissue engineering. Lastly, we aimed to improve the collagen gel properties by the hybridization with silica inorganic component through a sol-gel technique. The hybrid hydrogels showed improved viscoelastic properties, higher stiffness, chemical stability and in vitro apatite-forming ability. The rMSCs in the hybrid gels showed better performance for osteogenic differentiation while preserving the cell proliferative potential of collagen gel. Taken all, the hydrogel-culture of stem cells helps effective loading of cells within 3D porous scaffolds, provides tissue-mimic environments appropriate for proliferation and possibly for osteogenic differentiation when proper cues were provided. Furthermore, improvement of hydrogels by the inorganic-organic hybrid approach is considered to be promising particularly for driving stem cells to bone tissue engineering. 생체 모방형 3차원 구조체인 스캐폴드의 사용은 뼈 재생을 위한 효과적인 접근 방법으로 여겨지고 있다. 최근에는 최적의 재생 환경을 조성하려는 목적으로, 3차원 스캐폴드와 결합한 줄기 세포를 연구에 대한 관심이 많아지고 있다. 본 연구에서는, 뼈 재생을 위해서 조직 공학용 3차원 하이드로젤 융합형 스캐폴드 - 특히 줄기세포를 함유하는데 용이하고, 분화를 촉진시킬 수 있는 환경을 제공하기 위함 – 개발에 주안점을 두었다. 이는 새로운 조직 공학의 접근방법으로 스캐폴드에 줄기 세포를 3차원적으로 부착하는데 효과적이며, 이로 인해 우수한 골분화를 이끌 것으로 기대된다. 본 연구에서 개발된 스캐폴드는 3가지 종류로 구분된다. 첫 번째 연구에서는 콜라겐 젤과 결합한 세라믹 스캐폴드를, 두 번째 연구에서는 콜라겐 젤과 결합한 고분자 스캐폴드를, 세 번째 연구에서는 콜라겐 실리카 하이브리드 복합체를 하이드로젤 형태로 제조하였다. 모든 하이드로 젤 안에는 줄기세포가 함유되어, 적절한 3차원 환경을 제공하도록 설계되었다. 첫 번째 연구에서는 콜라겐 젤과 결합한 세라믹 스캐폴드에 세포의 성장과 분화의 효율성을 조사하였다. 콜라겐 젤과 결합한 세라믹 스캐폴드에 있는 줄기세포는 높은 성장률을 보였고 이는 콜라겐 하이드로젤과 유사한 성장 패턴을 보였다. 이 방법은 직접적으로 세라믹 스캐폴드에 분주한 것보다 초기의 세포 부착을 두 배 이상 증가시키는 중요한 역할을 하였고, 배양 후 14일 차에는 세포의 높은 성장률과, 골 형성 세포의 분화 초기 마커인 알칼라인 포스파타제의 활성이 증가됨을 보였다. 또한 골세포 분화 마커인 오스테어칼신 (osteocalcin, OC), 오스테오폰틴 (osteopontin, OPN), 그리고 뼈 시알로단백질 (bone sialoprotein, BSP)을 확인한 결과 유전자 발현이 증가함을 보였다. 또한 골 관련 단백질 발현도 증가함을 보였고, 기질의 미네랄화하면서 칼슘 농도를 증가시켰다. 두 번째 연구에서는 3차원 배양 조건인 flow perfusion 시스템 안에서 줄기세포를 함유한 콜라겐 젤과 결합한 고분자인 폴리카프로락톤 (poly-caprolactone, PCL) 스캐폴드을 제조하였다. 콜라겐은 세포가 성장하는데 유리한 환경을 제공한다. 콜라겐 젤과 결합한 PCL 스캐폴드에 있는 줄기세포는 PCL 스캐폴드에 직접 부착된 경우의 줄기 세포에 비해 높은 증식률을 보였다. 또한 동적 배양 환경에서의 효과를 연구하였다. static culture 보다 flow perfusion 시스템 안에서 콜라겐 젤과 결합한 PCL 스캐폴드에 있는 줄기세포가 증식률과 골세포 분화를 향상시켰다. 또한 배양 후 21일차에서 세포의 증식률과 골세포 분화인 유전자와 단백질이 상당히 촉진됨을 확인할 수 있었다. 마지막 연구에서는 솔-젤법을 이용한 콜라겐 실리카 하이브리드 복합체를 하이드로젤 형태로 제조하였다. 또한 점탄성 특성을 지닌 하이브리드 젤의 기계적인 성질을 측정한 결과, 힘을 가했을 때 변형의 저항성을 증가시켰고, 동적인 진동을 받았을 때 더 높은 강도를 보였다. 하이브리드 젤은 분해를 억제하고 화학적인 안정성을 향상시켰고, 아파타이트를 형성을 촉진시켰다. 하이브리드 젤 안에서 세포는 더 높은 부착과 증식을 보였고 반면에 수축은 상당히 감소함을 보였다. 더욱이 골세포 분화가 상당한 증가를 보였다. 이러한 연구들을 종합해 볼 때, 줄기세포를 융합한 스캐폴드는 생체적 우수성을 지니고, 재생에 매우 효과적이었음을 알 수 있었다. 특히 바이오 세라믹과 고분자 재료와의 복합화를 통한 향상된 특성 (기계적 또는 성형성) 을 갖추며, 하이드로젤의 3차원 환경을 제공할 수 있는 등 새로운 조직공학적 접근방법을 제안할 수 있었다. 본 연구에서 제시된 하이드로젤 결합형 3차원 스캐폴드는 줄기세포 배양과 뼈 조직공학에 응용되리라 기대된다.

Substrate Curvature Effects on Adaptive Architecture and Mechano-response of Epithelia

Sun-Min Yu Graduate School of UNIST 2020 국내박사

Curvature is a geometric feature widely observed in the epithelia and closely related with the physiological functions of epithelial organs such as intestinal villi and renal tubules. Despite the mounting in-vivo evidence showing that curvature on spatiotemporal organization of cells and tissues, current understanding on how it affects biophysical behaviors of cells is still elusive. Thus, elucidating curvature effect is, indeed, important to design artificial scaffolds and understand tissue organization. In current thesis work, we aimed to understand the effect of 3D curved surface on epithelial cell behaviors of its morphological characteristics and mechano-response by varying the geometrical features of curved surface. Scale of curvature relative to cell size is critical to understand the curvature effect on cell systems, ranging from the sub-cellular to the supra-cellular scales, and plays an important role in both morphogenesis and pathology. To dismantle complexity in curvature effect, sculpting fine curved structure is highly important which can vary the scale of curvature, while quantitative measurement of cellular feature is essential to reveal curvature effect on the cells. Functions of kidney are precisely controlled by segmented renal tubules, which responsible for reabsorption and secretion of filtrate. The structural characteristic of kidney tubule supports the key functions of kidney by having broad range of tubule size and sophisticated shape. To investigate the effect of substrate curvature, we generated convex and concave cylinder-like channels by microfabrication techniques, having broad range of principal curvature, 𝜅 (channel width: 90 ~ 1000 μm , |𝜅|≤ 0.033 μm−1. Then, we examined the effect of substrate curvature on the shape and phenotype of two kinds of renal epithelial cells cultured on microchannel. We found that cell morphology and alignment were controlled by several factors, including the sign (convex or concave. and the degree of 3D surface curvature, the mechanical stiffness of individual cells, and cell density. Furthermore, we demonstrated that renal epithelial cells showed improved apical-basal polarization effects on the substrate with substrate curvature. Our study suggests that curvature is an important guiding principle for the development of advanced tissue models and that curved and geometrically complex structures can regulate cell morphology and phenotype. Complex shape in native tissue is closely related with original function of organs and loss of native shape is associated pathological condition of epithelial organs such as tumor progression and polycystic kidney disease. Although the epithelial tubule possesses cylindrical tubule shape as a basic architectural unit, one cannot fully explain the complexity of in-vivo epithelial tissue shape with only cylindrical shape. Curvature of 3D shape can be formally described with Gaussian curvature which indicates shape and scale of the curvature on the surface. To understand cell behaviors by non-constant curvature, we prepared confluent epithelial cells on a torus structure presenting positive, zero, and negative Gaussian curvatures with a tubule diameter of 3–7 cells by two-photon polymerization (TPP. laser lithography. We found that, both cell bodies and nuclei, adapted on the torus surface, exhibited local Gaussian curvature-dependent preferential orientation. Besides, nucleus adaptation was not identical with that of cell body, which can find from nuclear area adjustment and asymmetric nuclear position depending on the local Gaussian curvature. Furthermore, the spatial heterogeneity of two intermediate filament proteins related to mechanoresponsive expression of the cell body and nucleus, vimentin and lamin A, revealed local Gaussian curvature as an important guidance cue in mechanical adaptation of epithelial cells. Altogether, we elucidated that cells can sense and adapt to Gaussian curvature regarding its morphological change and mechanobiological response. This finding can expand our understanding on curvature effect with formal description on curvature of 3D surface having non-uniform Gaussian curvature, suggesting Gaussian curvature as an important physical factor in harnessing mechanobiological response of epithelial cells. Lastly, we also studied about geometric corner effect of 3D structure, especially on impacts of geometry on convex surface. We cultured cells on various protruded convex structure such as triangle, square and circle shape, which precisely fabricated by TPP laser lithography. In this topic, we further tried to elucidate role of intermediate filaments and other cytoskeleton such as microtubule and actin. Morphological data indicates that epithelial cells can sense the sharpness of the corner by showing the characteristic cell alignments. In addition, intermediate filaments, vimentin and cytokeratin 8/18 play an important role in the growth and adaptation of epithelial cells by improving the expression level of convex structures depending on the shape. Furthermore, the microtubule building block α-tubulin also responds to the 3D geometry, indicating that the intermediate filament and microtubules can cooperatively secure the mechanical stability of epithelial cells on the curved surface. In conclusion, substrate curvature can control the shape and organization of epithelial tissue and epithelial cells actively respond to curvatures on curved surface by re-organization of shape and skeletal elements of cell and nucleus to gain physical stability. The current work can increase our understanding of mechanical adaptations of cells on curved surfaces, reflecting in-vivo 3D tissue geometry in diverse biological processes such as morphogenesis, tissue homeostasis, and tumor progression, and provide useful insight for a wide range of applications including artificial scaffold, organ-on-a chip as a guidance cue.

America(s) in early twentieth century ethnic minority writing : Younghill Kang and Richard Wright

Yu, Byung Sun UMI Dissertation Publishing ProQuest LLC 2014 국내박사

Effects of mass Dransfer in liquid phase catalytic consecutive hydrogenation of 2,6-Dinitrotoluene

Yu@celen, Fu@sun s.n.] 1984 국내박사

중국 네티즌의 가상아이돌의 대한 구독의도에 대한 연구

SUN YU 충북대학교 일반대학원 2024 국내석사

This study aims to demonstrate the causal relationship between the features of virtual idols and netizen characteristics regarding subscription intentions, as well as the mediating role of immersion. Building upon previous research, the features of virtual idols are divided into four dimensions: authenticity, anthropomorphism, control, and quasi-social interaction. Netizen characteristics are categorized into three dimensions: sociability and self-consistency. In addition, immersion plays a mediating role. To achieve the research objectives, a questionnaire survey was conducted among netizens who have watched live broadcasts or content of virtual idols. The survey was distributed online through the Chinese questionnaire survey platform "Wenjuanxing." A total of 374 valid questionnaires were analyzed. The suitability of the research model designed was examined using SPSS 26.0 and AMOS 26.0 software, and the relationship between different variables was validated. Reliability analysis, exploratory factor analysis, frequency analysis, confirmatory factor analysis, and structural equation modeling were employed to validate these issues. The analysis results are as follows: among the features of virtual idols, authenticity, anthropomorphism, control, and quasi-social interaction have a significant impact on immersion. Among the characteristics of netizens, sociability and self-consistency are found to have a significant impact on immersion. Within the features of virtual idols, authenticity and control significantly affect subscription intentions. Among the characteristics of netizens, self-consistency significantly affects subscription intentions. The study found that immersion has a significant impact on subscription intentions. After testing the mediating effects, it was found that authenticity, control, quasi-social interaction, sociability, and self-consistency exhibited indirect effects through partial mediation. Based on the empirical analysis results, the study proposes the following recommendations. The research indicates that the contents created by virtual idols should possess authenticity, and the control of virtual idols' language should minimize linguistic and behavioral errors, thereby enhancing the anthropomorphism of their image and behavior. This can lead netizens to be more immersed in the live broadcasts and content produced by virtual idols, ultimately increasing netizens' intention to subscribe to virtual idols. Regarding the moderating effects, the preference for ACG (anime, comic, and game) shows a negative moderating effect on the relationship between control, quasi-social interaction, and immersion, as well as between self-consistency and subscription intentions. The analysis results are as follows: among the features of virtual idols, authenticity, anthropomorphism, control, and quasi-social interaction have a significant impact on immersion. Among the characteristics of netizens, sociability and self-consistency are found to have a significant impact on immersion. Within the features of virtual idols, authenticity and control significantly affect subscription intentions. Among the characteristics of netizens, self-consistency significantly affects subscription intentions. The study found that immersion has a significant impact on subscription intentions. After testing the mediating effects, it was found that authenticity, control, quasi-social interaction, sociability, and self-consistency exhibited indirect effects through partial mediation. Based on the empirical analysis results, the study proposes the following recommendations. The research indicates that the contents created by virtual idols should possess authenticity, and the control of virtual idols' language should minimize linguistic and behavioral errors, thereby enhancing the anthropomorphism of their image and behavior. This can lead netizens to be more immersed in the live broadcasts and content produced by virtual idols, ultimately increasing netizens' intention to subscribe to virtual idols. Regarding the moderating effects, the preference for ACG (anime, comic, and game) shows a negative moderating effect on the relationship between control, quasi-social interaction, and immersion, as well as between self-consistency and subscription intentions. Key words: Virtual idol, Netizen, ACG preference, live broadcasts, Subscription intentions, Flow * A thesis for the degree of Master in August 2023.

Changes in ovarian GnRH mRNA in response to treatment with PMSG AND/OR hCG

Sun Kyeong Yu 서울대학교 1990 국내석사

Effectiveness of written text and audiovisuals on incidental vocabulary learning in kindergarten English learners

Park, Yu Sun 韓國外國語大學校 敎育大學院 2023 국내석사

The present study aimed to investigate the effectiveness of two different input modes, written text and audiovisual on incidental vocabulary learning. The participants included 41 parents whose children attended a private English institute, so called “English Kindergarten” in Korea. The questionnaire was provided to them to collect background information as well as their perception of input modes. Twelve 5-year-old and twelve 6-year-old students were also involved in this study. The multiple-choice tests were conducted to assess the effect on receptive vocabulary knowledge, and oral tests were to evaluate the productive vocabulary knowledge after the students watched the educational videos or read the transcripts. The result showed significant vocabulary gain and retention through both input modes in regard of receptive vocabulary knowledge, indicating both written text and audiovisuals were effective for young English learners to obtain the meaning of target words successfully. However, it was also found that both input modes were not as much as effective for the productive vocabulary knowledge. It suggests that teachers should include a variety of productive activities while they may use varied input modes as both input modes showed notable improvements in receptive vocabulary knowledge. This study considered the preferences of both children and parents. The result of the questionnaire collected from their parents showed that the younger children preferred viewing videos, and also revealed a longer average time of watching videos regardless of parents’ preferences for providing written text to their children at home. Taking the result of each research question together, the study discussed pedagogical implications, using varied modes according to learners’ preferences for a more engaging and enjoyable experience in terms of vocabulary learning since it showed significant receptive vocabulary growth through both written text and audiovisuals. It also implies the necessity of developing criteria, particularly for audiovisuals to provide an appropriate level of materials to young English learners. Lastly, the study provides suggestions for future research based on the limitations of this study such as a larger sample size with varied learner profiles, lack of comparing the effect of input modes due to the absence of a control group, and a longer interval between posttest and delayed posttests would be needed for a more robust conclusion. The necessity of studies regarding audio input was also derived from the result of this study. 본 연구는 한국 유치원 영어 학습자의 부수적 어휘 학습에 대한 문자 텍스트와 시청각 자료의 두 가지 입력 모드의 효과를 비교하는 것을 목적으로 하였다. 이 연구는 한국의 '영어 유치원'으로 불리는 사설 영어 학원에 재학 중인 만 5세와 만 6세 아동 12명(총 24명)을 대상으로 실험을, 그리고 41명의 학부모 대상으로 설문조사를 실시하였다. 연구 결과, 두 가지 입력 모드 모두에서 유의미한 어휘 학습이 이루어졌지만 두 입력 모드 간에는 유의미한 차이가 없는 것으로 나타나 두 가지 입력 모드 모두 유아 학습자가 목표 단어를 습득하고 유지하는 데 동등하게 효과적이라는 것을 알 수 있다. 그러나 두 가지 입력 모드 모두 객관식 테스트를 통해 조사한 수용적 어휘 지식에 비해 구술 시험에서 볼 수 있는 생산적 어휘 지식에는 효과적이지 않은 것으로 나타났다. 이는 어휘 지식이 동등하게 향상되는 것으로 나타난 만큼, 교사가 다양한 입력 모드를 사용하되 생산적인 활동을 다양하게 포함시켜야 함을 시사한다. 본 연구에서는 어린이와 학부모의 선호도를 고려하였다. 설문조사 결과, 대다수의 부모가 글로 된 텍스트를 선호하는 것과는 달리 어린 자녀일수록 동영상 시청을 선호했으며, 동영상 시청에 소요되는 평균 시간도 더 긴 것으로 나타났다. 각 연구 질문의 결과를 종합하여 본 연구에서는 어휘 학습의 효과는 동일하므로 학습자의 선호도에 따라 다양한 모드를 사용하여 보다 흥미롭고 재미있는 경험을 제공하는 것이 정의적 측면에서 적절하다는 점을 시사한다. 또한 어린 영어 학습자에게 적절한 수준의 자료를 제공하기 위한 시청각 자료의 기준 개발의 필요성을 제시하였다. 마지막으로 본 연구는 적은 표본 수와 시간적 제한으로 일주일 사후지연시험을 실시하였고 학부모들에 의하여 추가된 오디오 입력의 효과를 비교하지 않은 한계점을 가지고 있다. 이를 바탕으로 후속 연구의 필요성을 제시한다.

Sustained and transient reward effect on cognitive control in schizophrenia : the relevance of negative symptoms

Chung, Yu Sun UMI Dissertation Publishing ProQuest LLC 2014 해외박사