彈塑性 應力集中部에서의 初期疲勞龜裂傅播壽命의 豫測

趙相明(Sang-Myung Cho),堀川浩甫(Kohsuke Horikawa) 한국해양공학회 1988 韓國海洋工學會誌 Vol.2 No.2

In order to consider the concept of the 'fitness for purpose' in fatigue design of offshore structure, fracture mechanics is applied to evaluate initial or weld defects.<br/> Generally, linear elastic fracture mechanics has been applied to estimate initial fatigue crack propagation rate as well as long fatigue crack propagation rate. But, initial fatigue crack propagation rate in elasto-plastic notch field may not be characterized by application of stress intensity factor range △K, because plastic effect due to stress concentration of notch may contribute to initial crack propagation. Therefore, to introduce the plastic effect into fatigue crack driving force, in this studty, the evaluating method of J -integral range △J, was developed for initial fatigue cracks in elasto-plastic notch field. The interpolation function for J -integral by Willson was modified for application to notch field. In calculation of △J obtained from the modified J -integral, stress gradient and crack closure behavior in the notch field were considered.<br/> The initial crack propagation rates in the notch fields of mild steels and high tensile strength steels were correlated to △J. As the result, it was cleared that the present △J is applicable to characterize the fatigue crack propagation rates in both the elastic and elasto-plastic notch fields.

'린 스타트업' : 창업 초기기업의 실패 최소화 전략

조성주,이상명,박병진,Cho, Sungju,Lee, Sang-Myung,Park, Byung-Jin 한국벤처창업학회 2014 벤처창업연구 Vol.9 No.4

최근 한국경제의 화두가 되고 있는 창업활성화를 위해서 많은 논의와 정책이 이루어지고 있으나, 결국 창업활성화는 창업 기업의 성공률이 높지 않다는 문제가 해결되어야 한다. 특히, 창업초기의 높은 실패율을 낮출 수 있는지의 여부가 창업활성화의 성패를 좌우하는 중요한 요인이 될 것이다. 이에 본 연구에서는 창업 초기기업의 실패 최소화 전략으로서 매우 유용한 시각을 제공하지만 그간 국내 학계에서 체계적으로 연구되지 않은 '린 스타트업'을 살펴보고, 이를 바탕으로 창업기업의 활용방안을 모색해 보고자 하였다. 구체적으로 린 스타트업'의 기본 프레임워크와 핵심원칙에 대한 설명과 함께, 창업기업의 사업추진 단계별 린 스타트업 개념의 적용방법을 사례를 통해 알아보는 한편, 린 스타트업'을 적용하는데 있어서 고려해야 할 사항을 제시하였다. 본 연구는 창업가가 실행할 전략뿐만 아니라 창업 실습을 가르치는 교육자와 창업 기업에 대한 멘토링을 제공하는 전문가들에게 효과적인 프레임웍이 될 수 있도록 전체적인 프로세스를 종합적으로 살펴보았다는 데 의의가 있다. There has been lots of discussions and new policies to encourage people to start new businesses. However, they key issue such as how to raise the success rate of new start-ups still needs to be resolved. Many believe that the success of policies and discussions for promoting entrepreneurship in Korea highly depends on how to lower the risks with which early stage start-ups encounter. In this backdrop, this study aims at providing an emerging approaches in entrepreneurship, 'lean start-up', which can work as an effective method with which early stage entrepreneurs can minimize challenges they face. Even though lean start-up is a widely accepted concept among practitioners and recognized as a useful tool for entrepreneurship and education, but has not got deserved attention from the academic world. This paper offers basic framework and key principles of lean start-ups, furthermore, shows Korean cases of step-by-step application methods of its concepts. It also suggest key issues in adopting lean start-up strategy. This study has implications and contributions for entrepreneurs, educators and researchers through providing comprehensive perspectives on process of the lean start-up strategy.

TIG클래딩 공정에 대한 품질 모니터링기법의 개발

조상명,박정현,손민수,Cho, Sang Myung,Son, Min Su,Park, Jung Hyun 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.6

Pipe inside clad welding is mainly used to the flow pipe of sub-sea or chemical plant. For the inside clad welding to the medium pipe with the diameter of about 12", TIG welding is frequently applied with filler metal. In this case, the clad welding has the very broad weld area over $10m^2$. And, the non-destructive test (NDT) such as ultrasonic test (UT) or radiographic testing (RT) should be conducted on the broad weld area, and it costs very high due to the time-consuming work. Therefore, the present study investigated the variation of arc voltage to develop the in-line quality monitoring system for the pipe inside TIG cladding. The 4 experimental parameters (current, arc length, wire feed position, and shield gas flow rate) varied to observe the change of arc voltage and to establish the model for the monitoring. The arc voltage was decreased when the wire was fed to the backward eccentric position(over 2mm), and the shield gas flow rate was insufficient under 10L/min. In the case of the backward eccentric position over 2mm, the bead appearance was not good and the dilution ratio was increased due to deep penetration. When the shield gas flow rate was lower than 10L/min, the bead surface was oxidized.

벤처 창업팀의 다양성이 창업 성과에 미치는 영향에 관한 연구

조성주 ( Sungju Cho ),이상명 ( Sang-myung Lee ) 한국중소기업학회 2020 中小企業硏究 Vol.42 No.1

지금까지 창업 성과에 관한 연구는 주로 창업자의 특성, 역량, 전략이 성과에 미치는 영향에 관한 연구들이 주를 이루고 있었다. 그러나 과학기술의 발달과 경영환경의 복잡성은 개인에 의한 창업보다 창업팀에 의한 창업을 활성화시키고 있다. 이에 따라 창업팀 특성이 창업 초기 기업에 미치는 영향에 대한 이론적이고 실제적인 연구의 필요성이 제기되었다. 본 연구는 벤처 창업팀의 다양성이 창업 성과에 미치는 영향을 확인하였다. 연구 모형을 검증하기 위해 전국 17개 지역, 18개 창조경제혁신센터 사업에 참여한 적이 있는 벤처 창업 기업 중 287명의 대표가 응답한 설문을 바탕으로 회귀분석을 통해 가설을 검정하였다. 분석 결과, 인구통계적 다양성에서는 성별 다양성만 비재무적 성과에 부정적 영향을 미쳤다. 정보 다양성은 경력 다양성이 재무적 성과에, 교육수준 다양성이 비재무적 성과에 긍정적 영향을 미쳤다. 또한 이전 공유경험이 높을수록 재무적 성과에 긍정적 영향을 미친 것으로 나타났다. 가치 다양성은 재무적, 비재무적 성과 모두에 부정적인 효과를 미쳤다. 이상의 연구 결과를 기반으로 연구의 시사점과 향후 연구 과제 등을 제시하였다. Many researchers conducted studies on the relationship between entrepreneur’s characteristic, capability, strategy and performance of new venture. However, the development of scientific technique and the complexity of the business environment have stimulated entrepreneurial teams rather than individuals. Therefore, the necessity of theoretical and practical study on the effect of the characteristics of an entrepreneurial team on the new venture companies was suggested. Initial research on entrepreneurial team diversity has primarily addressed the impact of demographic diversity on performance. In order to verify the research model of this study, 287 delegates of new venture companies that participated in the projects at the 18 Centers for Creative Economy & Innovation in 17 regions of the country conducted validity and reliability test based on the questionnaire to which they answered. The result shows that only gender diversity among demographic diversity affected non-financial performance. Information diversity influenced career diversity on financial performance and diversity in education on non-financial performance. Also, the higher the previous sharing experience, the better the financial performance. Value diversity has negative effect on both financial and non-financial performance. Based on the results, theoretical and practical implications are derived. Also suggested are methodological limitations and future research directions.

용접용 용가재 용융금속 이행현상에 미치는 표면장력과 점성계수의 영향

조상명(Sang-Myung Cho) 대한용접·접합학회 2018 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2018 No.11

아연도금강판에 대한 중첩펄스 MIG 용접에서의 파형제어와 기공 발생 특성

조상명,김기정,이병우,Cho Sang-Myung,Kim Ki-Jung,Lee Byung-Woo 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.1

Recently, application of arc welding to galvanized carbon steel sheet is on the increasing Ould in the fields of automobile and construction industries. In arc welding process, zinc is evaporated in weld pool, even under the appropriate welding condition and produce blowhole and/or pit. Zinc gas cause instability of arc and increase spatter and fume. This research is purposed to minimize the heat-input and the formation of porosities in the welded joint of the galvanized carbon steel sheet using variable polarity AC wave pulse MIG welding system. An appropriate welding condition which showed low spatter and good bead appearance was acquired by applying the AC pulse MIG welding machine to DC duplicated MIG welding with the solid wire. When oxygen gas was added to shield gas of MIG welding for galvanized steel sheet, arc length was increased and arc stability was improved. In the AC duplicated welding, the loss of galvanized layer was decreased as the amount of heat-input was decreased when the EN ratio was increased under the condition that average welding current was evenly set.

4차 산업혁명에 적합한 미래용접의 모습은?

조상명(Sang Myung Cho) 대한용접·접합학회 2017 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2017 No.11

내마모판의 광폭 경화육성 용접비드 형성을 위한 트윈토치 CMAW 공정개발

조상명,김성덕,황규민,Cho, Sang-Myung,Kim, Sung-Deok,Hwang, Kyu-Min 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.2

The wearplate with Cr-C has been used in condition of severe abrasion. Recently, the demand of wearplate made by hardfacing with Cr-C has increased in the world, but it is lack of supply and expensive due to low productivity. CMAW (Compound Metal Arc Welding) is very useful process of several welding methods to make wearplate. In this paper, twin torch CMAW to use twin torch at the same time was developed to improve productivity and to ensure quality of wear plate. When the distance between two touches was smaller than 30mm, arc blow was occurred. However when the distance was larger than 35mm, there was no arc blow any more. If the oscillation path of each torch was overlapped together, the melt through at the overlapped zone was occurred due to concentrated heat input in substrate. On the other hand, the turning point of each torch was open more than 5mm, separated bead was generated. Therefore twin torch CMAW which has adequate conditions was able to make wearplate having flatter surface at the bead connection than single torch.

GaAs 를 이용한 X-Band 용 DBS 수신기 전단부의 MMIC 설계

조승기(Seung-Ki Cho),이진구(Jin-Koo Rhee),김상명(Sang-Myung Kim),조광래(Gwang-Rae Cho),윤현보(Hyun-Bo Yoon) 대한전기학회 1987 대한전기학회 학술대회 논문집 Vol.1987 No.7

9%Ni강에 대한 FCAW와 Super-TIG용접의 비교

조상명(Sang Myung, Cho) 대한용접·접합학회 2019 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2019 No.11