적층제조를 활용한 골재생용 세포지지체 제작의 효용성 강화를 위한 몇 가지 방법에 대한 소고

조영삼(Y.-S. Cho) Korean Society for Precision Engineering 2023 한국정밀공학회 학술발표대회 논문집 Vol.2023 No.5

중국 일대일로 전략의 추진현황 평가와 향후 대응과제

조영삼(Youngsam Cho),최낙섭,김양팽,김단비 산업연구원 2016 연구보고서 Vol.- No.-

자연 나노헤어 구조물의 부착 기능에 대한 개관

조영삼(Young-Sam Cho),허신(Shin Hur),이지혜(Jihye Lee),이준희(Jun-Hee Lee),민태진(Taijin Min),김완두(Wandoo Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

In nature, some creatures have the ability to walk vertically or upside down on various natural surfaces. The mechanism of adhesion can be capillarity, viscosity of adhesive secretion, interlocking or intermolecular force an so on. In this paper, we focus on the intermolecular force generated by nano-size hair-like structures of creatures and natural surfaces and we introduce briefly the mechanism of adhesion with intermolecular force and other mechanism of adhesion. And we enumerate the creatures which have various size of nano-hair structures and the manufactured nano-hair structures which mimic the nature.

나노헤어의 기계적 특성이 부착에 미치는 영향

조영삼(Young-Sam Cho),한혁섭(Houkseop Han),김완두(Wan-Doo Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

Nano-hairs, which can be found on the epidermis of Tokay gecko's toes, contribute to the adhesion by means of van der Waals force and capillary force. This structures have inspired many researchers to fabricate the attachable nano-structures. However, unfortunately, the efficiency of artificial nano-structures is not assurable sufficiently. Moreover, the mechanical parameters related with the nano-hair's attachment are not yet revealed qualitatively. In this study, we investigate the mechanical parameters which have influence on the ability of adhesive nano-hairs through numerical simulation considering only van der Waals force. For the numerical analysis, finite element method is utilized and van der Waals force, assumed as 12-6 Lennard-Jones potential, is implemented as the body force term in the finite element formulation.

건식부착물 제작에 대한 개관

조영삼 ( Young Sam Cho ) 한국고무학회 2009 엘라스토머 및 콤포지트 Vol.44 No.2

자연계에 존재하는 다양한 생명체 중 몇몇은 벽이나 천장을 자유자재로 걸어다니거나 뛰어다닌다. 이러한 생명체중 대표적으로 Tokay Gecko는 그 발가락 표피에 수십억개의 주걱모양의 나노헤어를 가지고 있으며, 이러한 나노헤어는 부착하고자 하는 표면과의 원자수준의 끌어당기는 힘을 발생시키게 되며 이 힘을 이용해 접착제 없이 부착력을 얻게 되는 것이다. 최근 7~8년 동안 많은 연구자들은 이를 모방한 건식부착물의 제작 연구를 수행하고 있으며, 본 논문에서는 이러한 연구들의 개관을 통해 향후 연구방향에 대해 논의하고자 한다. In nature, some creatures have the ability to walk vertically or upside down on various natural surfaces. One of them, Tokay Gecko has billions of nano-hair at the epidermis of its digital. These nano hairs makes atomistic attractive force to the surface, therefore, it could walk and run on the vertical or upside surfaces. Recently, many researchers tried to fabricate the dry adhesive structure mimicking the nano-hair structure. in this study, I tried to survey these studies to discuss the direction of future fabrication works of dry adhesive structures.

유효강성을 줄인 새로운 형상의 건식부착물 제작

조영삼(Young-Sam Cho),정대환(Dae-Hwan Jung),한혁섭(Houkseop Han),김완두(Wan-Doo Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

In the fabrication of dry adhesive structure, increasing contact-points or contact-area is the primary goal because the adhesive force grows in proportion to the contact-area. The simplest way to extend the contact surface is the fabrication by using soft materials. However, the column-array structure could confront the matting phenomenon which columns are stuck together. Therefore, we need a novel design to reduce the effective stiffness with adequate stiff materials like a gecko’s setae. In this study, we propose a novel design for the dry adhesive structure. Moreover, we analyzed whether the adhesive structure conforms the rough surface sufficiently through finite element method adopted the non-bonding interaction as the body force. Also, we fabricated the novel structures via UV lithography and some techniques. In addition, we examined the adhesive force of the novel structures.

콜로이달 리쏘그래피를 이용한 건식부착물 제작

조영삼(Young-Sam Cho),박현하(Hyun-Ha Park),김재현(Jae-Hyun Kim),김완두(Wan-Doo Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Nano/micro column-array structures are usually suggested as dry adhesive structure due to enlargement of contact area between dry adhesive structure and substrate. For the fabrication of column-array structure, UV lithography, molding, and etching techniques are adopted. Because the critical scale of dry adhesive structures exists from hundreds nanometers to tens micrometer, every technique needs expensive mask or mold. In this study, we demonstrate that colloidal lithography, that is, a well-known etching technique using colloid as mask could be a promising fabrication technique for the dry adhesive structure with inexpensive mask.

서번트 리더십이 멕시코 종업원들의 이직의도에 미치는 영향:

조영삼(Cho, Youngsam),김영신(Kim, Youngshin),이재학(Lee, Jaehak) 한국인사관리학회 2018 조직과 인사관리연구 Vol.42 No.3

본 연구는 멕시코 현지 근로자들을 대상으로 서번트 리더십이 그들의 이직의도에 미치는 영향을 고찰하였다. 멕시코는 북미와 남미를 연결하는 전략적 요충지로서 풍부한 저가의 노동력에 기인하여 국내 선도기업들의 생산거점이자 수출 교두보로서의 중요한 역할을 해오고 있다. 연구를 수행하기 위해 방문한 멕시코 내 한국기업의 생산 자회사 관계자들과의 심층 인터뷰를 통해 현지노동시장에서의 높은 이직률로 인한 경영상 어려움과 이를 해결하기 위한 방안으로서의 사람중심 적 리더십의 중요성을 인지하게 되었다. 따라서 본 연구는 서번트 리더십에 주목함과 동시에 리더십과 구성원의 이직의도 간 관계에서 중요한 심리적 메커니즘으로서 리더신뢰 및 직무통제의 매개역할을 살펴보고자 하였다. 먼저 사회교환이론 관점에서 서번트 리더십 행위는 리더에 대한 구성원들의 신뢰를 높임으로써 그들의 이직의도를 낮출 것으로 예상하였다. 특히 본 연구는 또다른 매개변수로서 직무통제에 주목하였다. 이는 직무통제와 이직의도 간 관계에 대한 기존의 연구결과 들이 다소 혼재되어 있기에 본 연구에서는 이직이 용이한 멕시코 노동시장 환경에서 그 관계를 재조명해보고자 하였다. 경력이론은 개인, 조직, 노동시장의 역동적 관계를 통해 개인의 이직 메커니즘을 설명한다. 이직이 용이한 환경에서 직무통제 권한을 높게 인지하는 구성원들은 자기 역량에 대한 자신감과 외부의 구직기회로 인해 더 높은 이직의도를 가질 것으로 예상하였다. 구조방정식 모형을 이용한 실증분석 결과, 서번트 리더십과 이직의도 간의 직접적인 관계는 유의하지 않았으며 리더에 대한 신뢰와 직무통제가 그 관계를 매개하는 것으로 나타났다. 서번트 리더십은 리더에 대한 신뢰 및 직무통제와 모두 정의 관계를 보였다. 하지만 리더에 대한 신뢰는 이직의도와 부의 관계를 나타낸 반면 직무통제는 이직의도와 정의 관계를 나타냈다. 즉, 서번트 리더십은 두 가지 다른 메커니즘을 통해 이직의도에 상반되는 간접효과를 보여주었다. 본 연구결과는 서번트 리더십에 대한 인사관리차원에서의 이론적･실무적 시사점을 제공한다. The purpose of this study is to examine the effect of servant leadership on turnover intention of Mexican employees. Mexico has played an important roles as a production base and a bridgehead of export for Korean leading companies due to an abundant supply of cheap labor. Through the in-depth interview with managers of subsidiaries of Korean company in Mexico, we could realize managerial difficulties and importance of people oriented leadership, due to high turnover rate in the labor market. Thus, this study focuses on the relationship between servant leadership and turnover intention, and the mediating effects of trust in leader and job control as important psychological mechanisms. At first, we expect that trust in leader formed by servant leadership decreases turnover intention from the perspective of social exchange theory. Then we shed light on the relationship between job control, as another mediator, and turnover intention in Mexican labor market with plenty of employment opportunities, because there have been mixed results for the relationship. Drawing upon career theory, we expect that the employees who perceive higher authority of job control have higher turnover intention. Based on a structural equation modeling approach, the results indicated that servant leadership had no significantly direct effect on turnover intention, while trust in leader and job control mediated the relationship, respectively. Servant leadership was positively related to both trust in leader and job control. However, trust in leader was negatively related to turnover intention, while job control was positively related to turnover intention. That is, servant leadership had contrasting indirect effects on turnover intention through the two different mechanisms. The research findings provide theoretical and practical implications for servant leadership from the perspective of human resource management.

전산시스템 활용능력은 중요한가?: 변혁적 리더십과 직무열의 및 직무성과 관계에서의 조절역할

조영삼(Youngsam Cho),신종식(Jongsik Shin) 한국인터넷전자상거래학회 2020 인터넷전자상거래연구 Vol.20 No.2

This study aims to develop and empirically test a research model to better understand the relationship among transformational leadership, utilization ability for computational system, work engagement, and job performance. In particular, we focus on the direct effect of utilization ability for computational system and the interaction effect between transformational leadership and utilization ability for computational system on work engagement and job performance of employees. The results indicated that transformational leadership was positively related to both work engagement and job performance. Utilization ability for computational system was also positively related to the two outcome variables. Authors then examined the moderating effect of utilization ability for computational system among transformational leadership, work engagement, and job performance. The two interaction terms had the positive impacts on the two outcome variables of the employees. In other words, the positive relationships among transformational leadership, work engagement, and job performance were stronger when the perception of employees for their own utilization ability for computational system was higher. The findings suggest comprehensive implication in information technology and leadership research field by emphasizing the importance of utilization ability for computational system in organizations.

요소망 구성이 편리한 3차원 MLS 기반 변절점요소 개발

조영삼(Young-Sam Cho),박종연(Jong-Youn Park) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

In this study, we developed 3D MLS-based variable-node elements for easy meshing. These elements should be derived from 2D MLS-based variable-node elements and would be utilized as key elements of easy meshing technique we proposed. Using developed 3D MLS-based variable-node elements, we demonstrated several examples having complex configuration compared with conventional meshing technique. Moreover, we compared with the stress results of our model and conventional one.