RULED MINIMAL SURFACES IN PRODUCT SPACES

Jin, Yuzi,Kim, Young Wook,Park, Namkyoung,Shin, Heayong Korean Mathematical Society 2016 대한수학회보 Vol.53 No.6

It is well known that the helicoids are the only ruled minimal surfaces in ${\mathbb{R}}^3$. The similar characterization for ruled minimal surfaces can be given in many other 3-dimensional homogeneous spaces. In this note we consider the product space $M{\times}{\mathbb{R}}$ for a 2-dimensional manifold M and prove that $M{\times}{\mathbb{R}}$ has a nontrivial minimal surface ruled by horizontal geodesics only when M has a Clairaut parametrization. Moreover such minimal surface is the trace of the longitude rotating in M while translating vertically in constant speed in the direction of ${\mathbb{R}}$.

Ruled minimal surfaces in product spaces

Yuzi Jin,김영욱,박남경,신해용 대한수학회 2016 대한수학회보 Vol.53 No.6

It is well known that the helicoids are the only ruled minimal surfaces in $\RRR ^3$. The similar characterization for ruled minimal surfaces can be given in many other 3-dimensional homogeneous spaces. In this note we consider the product space $M\times\RRR$ for a 2-dimensional manifold $M$ and prove that $M\times\RRR$ has a nontrivial minimal surface ruled by horizontal geodesics only when $M$ has a Clairaut parametrization. Moreover such minimal surface is the trace of the longitude rotating in $M$ while translating vertically in constant speed in the direction of $\RRR$.

엘리 카르탕과 20세기 리만기하학

김영욱,Yuzi Jin,Kim, Young-Wook,Yuzi Jin 한국수학사학회 2009 Journal for history of mathematics Vol.22 No.2

엘리 카르탕은 20세기 기하학과 대수학의 한 획을 그은 업적을 낸 수학자이다. 이 논문에서 우리는 소수의 전문가에게는 친숙하지만 일반적으로는 생소한 그의 업적을 조명해 보고 그 영향을 알아본다. Elie Cartan is one of the mathematicians whose works marked the development of geometry and algebra of 20th century. We illuminate his mathematical contributions which is familiar to the experts but is alien to most of the mathematicians in general. Also we elucidate some of his influences.

송·원대의 과학에 대하여 II -금에서 원으로-

김옥자,김영옥,Jin, Yuzi,Kim, Young Wook 한국수학사학회 2015 Journal for history of mathematics Vol.28 No.3

This survey is the second part of the history of science of Song and Yuan dynasties and will covers the period from Jin to Yuan. Following the first part, we look at the calendrical astronomy, mathematics and medicine. In this survey we again follow Yabuuchi's work on the history of science of Song and Yuan period and Du Shiran's work on the history of science of China. We start from the sciences and mathematics of Jin which inherited those of Northern Song and see how they influenced the whole China including Yuan and Southern Song. As a conclusion the tendency to practical usages in the Southern Song as well as the suppression of Han people in Yuan prevented developments of theoretical sciences in Yuan and Ming later.

화장품 점포의 판매원 및 점포 요인이 구매만족에 미치는 영향

박진용(Park, Jin Yong),채단비(Chae, Danbi),장유지(Zhang, Yuzie) 한국상품학회 2014 商品學硏究 Vol.32 No.1

연구목적: 최근 화장품업계의 경쟁이 심화되면서 그에 대한 각 업체별 경쟁력 강화 방안 모색이 중요해지고 있다. 특히 과거와는 달리 소비자들의 가치지향적 소비 행태에 따른 제품 및 서비스에 대한 고품질의 경험 추구는 화장품업계로 하여금 소비자의 만족도 제고 방안으로써의 저가격-고품질의 기본적인 요소 외에 부가적인 경험요소에 대한 투자의 증대로 확대되었으며, 학문적으로도 이에 대한 검토가 요구되고 있다. 이에 본 연구에서는 소비자들이 화장품 점포 이용 시 만족에 영향을 미치는 경험적 요인으로서, 판매원요인과 점포요인의 평가를 고려하였다. 동시에 선행요인과 만족 간 관계에서 한국과 중국 간 소비자의 문화적인 차이의 수준을 조절효과로 검토하였다. 연구 설계 및 방법론: 연구목적의 수행을 위해 화장품 구매의 경험이 있는 전 연령층의 이용자들을 대상으로 선정하여 몰 인터셉트 방식으로 설문조사를 실시하였으며, 이를 통해 총 265부의 가용한 답변을 최종 분석에 사용하였다. 분석 및 연구 결과: 화장품 구매만족 제고의 선행요인들은 만족에 모두 유의적인 영향을 미치는 것으로 확인되었다. 그리고 만족에 대한 판매원요인의 영향은 한국보다 중국 소비자에게서 더 강하게 작용하는 것으로 나타났으며, 점포요인과 만족에 대한 영향은 한국 소비자에게서 효과가 더 강한 것으로 나타났다. 시사점 및 연구의 한계점: 본 연구는 이용자들의 화장품 구매만족에 영향을 미치는 요인으로써 판매원 및 점포요인에 대한 효과를 검증했다는 점과 한국과 중국의 문화적인 차이를 반영했다는 점에서 학술적 의미를 가진다. 실무적으로 본 연구는 화장품 브랜드 마케팅 관리자에게 유용한 시사점을 제공한다. 향후 연구방향: 향후 연구에서는 화장품 구매만족에 영향을 미치는 다양한 변수들을 활용한 연구모형 및 한국과 중국 이외 국가의 문화적 특성을 반영하는 보다 풍성한 연구가 기대된다. 공헌점: 본 연구는 화장품 구매만족에 미치는 요인으로써 판매원 및 점포환경 요인에 대한 효과를 검증하였다는 점과 이를 문화적인 차이로써 제시했다는 점에서 차별점을 갖는다. Purpose: As the growth rate of cosmetic related industry are increasing, managerial concerns how to increase of the satisfaction of value-orientated customers are getting important. Therefore the purposes of this study are multifold. The first is finding the antecedents of the satisfaction when consumer visit and buy at the cosmetic store. The second is examining the culture differences above causal-effect relations in China and Korea. Design/methodology/approach: For the relevant measuring, the constructs, cosmetic purchasing satisfaction, perceived evaluation of salespersons' competence and store environment are included. In the research model, the moderating effect of culture between Chinese and Korean consumers is examined. From the results of a survey from 265 customers, the effect of antecedents on the purchasing satisfactions is significant, including the relationship between two antecedents variables (salesperson and store environment) and cosmetics purchasing. Results/findings: This study provides the insight of the antecedents of cosmetic satisfaction are the salesperson competence and store environments. This study also provides insight of cultural differences between Chinese and Koreans. These insights provide practical guideline to marketing managers who are considering the cosmetic business in China and Korea. Research implications/limitations: Future work/research: A various of future studies are expected to adopt more specific and plentiful variables that affect the satisfaction of cosmetics purchasing in the research model. Originality/value: This study is examining the satisfaction in the cosmetic purchasing context. In the research model, the salesperson and store environment are considered as antecedents of satisfaction. Additionally, this study also provides insight of different levels of culture between Chinese and Korean consumers by moderating effects.

Increased Serum Cathepsin K in Patients with Coronary Artery Disease

Xiang Li,Lan Cui,Yuzi Li,Jiyong Jin,Dehao Jin,Xiangshan Li,Yanna Rei,Haiying Jiang,Guangxian Zhao,Guang Yang,Enbo Zhu,Yongshan Nan,Xianwu Cheng 연세대학교의과대학 2014 Yonsei medical journal Vol.55 No.4

Purpose: Cathepsin K is a potent collagenase implicated in human and animal atherosclerosis-based vascular remodeling. This study examined the hypothesis that serum CatK is associated with the prevalence of coronary artery disease (CAD). Materials and Methods: Between January 2011 and December 2012, 256 consecutive subjects were enrolled from among patients who underwent coronary angiography and percutaneous coronary intervention treatment. A total of 129 age-matched subjects served as controls. Results: The subjects’ serum cathepsin K and high sensitive C-reactive protein (hs-CRP) and high-density lipoprotein cholesterolwere measured. The patients with CAD had significantly higher serum cathepsinK levels compared to the controls (130.8±25.5 ng/mL vs. 86.9±25.5 ng/mL, p<0.001), and the patients with acute coronary syndrome had significantly higher serum cathepsin K levels compared to those with stable angina pectoris (137.1± 26.9 ng/mL vs. 102.6±12.9 ng/mL, p<0.001). A linear regression analysis showed that overall, the cathepsin K levels were inversely correlated with the high-density lipoprotein levels (r=-0.29, p<0.01) and positively with hs-CRP levels (r=0.32, p<0.01). Multiple logistic regression analyses shows that cathepsin K levels were independent predictors of CAD (odds ratio, 1.76; 95% confidence interval, 1.12 to 1.56; p<0.01). Conclusion: These data indicated that elevated levels of cathepsin K are closely associated with the presence of CAD and that circulating cathepsin K serves a useful biomarker for CAD.

Comparison of Bypass Surgery with Drug-Eluting Stents in Diabetic Patients with Left Main Coronary Stenosis

Xiaoxiao Zhao,Yujie Zhou,Hui Song,Like Guan,Guanbin Zheng,Zhehu Jin,Dongmei Shi,Yuzi Li,Yonghe Guo,Guo-Ping Shi,Xian Wu Cheng 연세대학교의과대학 2011 Yonsei medical journal Vol.52 No.6

Purpose: Several studies have compared the effects of coronary stenting and coronary-artery bypass grafting (CABG) on left main coronary artery (LMCA) disease. However, there are limited data on the long-term outcomes of these two interventions in diabetic patients. Materials and Methods: We evaluated 56 patients with LMCA stenosis who underwent drug-eluting stent (DES) implantation and 116 patients who underwent CABG in a single hospital in China between January 2004 and December 2006. We compared long-term major adverse cardiac events (death; a “serious outcome” composite of death, myocardial infarction, or stroke; and target-vessel revascularization). Results: In-hospital (30-day) mortality was 0% for the DES group and 3.4% for the CABG group (p=0.31). There was no difference between the two groups in terms of risk of death [hazard ratio for stenting group, 0.49; 95% confidence interval (CI), 0.13-1.63; p=0.55] or risk of serious outcome (hazard ratio for DES group, 1.11; 95% CI, 0.39-1.45; p=0.47). The target-vessel revascularization rate was higher in the DES group than in the CABG group (hazard ratio, 3.67; 95% CI, 1.24-11.06; p=0.018). Conclusion: In this cohort of diabetic patients with LMCA stenosis, there was no difference in composite endpoints between patients receiving DESs and those undergoing CABG. However, stenting was associated with higher rates of target-vessel revascularization than CABG. DES implantation in diabetic patients with LMCA disease was found to be at least as safe as CABG.