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$Cu_2(OH)_3(CH_3COO){\cdot}H_2O$로 부터 마이크로파를 이용한 $Cu_2O$와 Cu의 합성
송하철,허영덕,Song, Ha-Chul,Huh, Young-Duk 한국결정성장학회 2006 한국결정성장학회지 Vol.16 No.4
[ $Cu_2O$ ] and Cu have been synthesized from the layered organic-inorganic hybrid, $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$, assisted by microwave irradiation. $Cu_2O$ is formed in aqueous glucose solution, while metallic Cu is formed in ethylene glycol by reduction of $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$. The influence of microwave irradiation time and concentration of glucose on $Cu_2O$ particles formation and growth has been examined. The morphologies of $Cu_2O$ particles change from spheres with a few fm size to nanowires with diameter of 40 nm as increasing the microwave irradiation times. 층상 구조의 유기-무기 복합 소재 $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$에 마이크로파를 조사하면서 $Cu_2O$와 Cu를 합성하였다. 에틸렌 글리콜에서는 $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$이 환원이 되어서 Cu금속이 형성되는 반면에, 수용액에 글루코오스를 넣으면$Cu_2(OH)_3(CH_3COO){\cdot}H_2O$이 환원이 되어 $Cu_2O$가 형성되었다. 마이크로파 조사시간과 글루코오스의 농도가 $Cu_2O$의 입자의 생성과 성장에 미치는 영향을 확인하였다. 마이크로파의 조사시간이 길어질수록 $Cu_2O$의 입자는 수 ${\mu}m$의 구형에서 40nm의 지름을 가진 나노 선으로 변함을 확인하였다.
송하철(H. C. Song),염재선(J. S. Yum),김병일(B. I. Kim) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
After many casualties of conventional bulk carriers in recent years, a double hull bulk carrier was proposed to enhance the structural safety of a side shell and a transverse bulkhead. In this paper, two alternative structural designs of a double hull bulk carrier were carried out based on the Lloyd's rule. One has the double sided hull with longitudinal stiffeners and the other has that with a girder. The final structural design was examined in comparison with an existing single hull bulk carrier from the viewpoints of cargo hold capacity and the increases of weight and construction cost. Generally, the construction cost of a ship consists of the costs of material, labor and overhead cost. But, in this study, the relative construction cost concept was introduced to compare the economical validity more precisely. In this concept, fixed overhead cost is excluded in the assessment of construction cost, and only the variable overhead cost is added up to labor cost. As the result of this study, a double hull bulk carrier can be constructed within 1% increase of weight and construction cost.
유리섬유 보강재의 적층구성, 제작공법과 수지종류에 따른 구조강도 특성에 관한 연구
송하철(ha-Cheol Song),염재선(Jae-Seon Yum) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.5
Fiberglass-Reinforced Plastic (FRP) composites have been used for small fishing boats and leisure boats for many years. These composites have different physical characteristics, depending on the constitution of lay-up and manufacturing method. Recently, new manufacturing methods, such as vacuum infusion, have been used to make the composites lighter and stronger. In this research, the mechanical properties of fiberglass reinforcements with constitution of lay-up, manufacturing method, and two different resins were investigated experimentally. It was found that the mechanical properties of FRP composites increased with increasing thickness, with the use of vacuum infusion method, and with the use of vinyl ester resin. The mechanical properties of diverse FRP composites can be used as a practical guide for selecting appropriate materials for specific applications.
송하철(Ha-Cheo. Song),서무천(Mu-Cheon Seo),염재선(Jae-Seon Yum) 한국항해항만학회 2010 한국항해항만학회지 Vol.34 No.10
2000년대 이후 한국의 조선산업은 설계 및 생산기술력의 국제경쟁력을 바탕으로 세계를 선도하는 조선 1위국의 위상을 다져왔다. 최근 중국의 급격한 경제성장으로 인해 아시아 주요 3국(한국, 일본, 중국)의 해상물동량은 전 세계 해상물동량의 30%에 달하며 한국 해운산업 역시 새로이 건설된 대형 항만의 활성화에 힘입어 세계 10위권에 해당되는 등, 선박 수리 분야에 대한 막대한 국내 수요에도 불구하고 한국의 수리조선산업에 대한 경쟁력 분석을 수행한 연구는 드문 실정이다. 본 연구에서는 수리조선소 경쟁력의 주요지표인 입지여건, 수리비용 및 기술경쟁력을 중심으로 세계 주요 수리조선국과의 국제경쟁력을 비교 분석한다. Since 2000's, Korea has became the world-leading shipbuilding country with the competitive technologies in design and production. And with the China's economic growth, the three economies (Korea, Japan and China) handle 30 percent of the world`s freight cargoes. Shipping industry of Korea has been also grown up to the top 10 of the world with the newly constructed large ports. In spite of the growing demand for ship repair in Korea, its competitiveness analysis has been insufficient. This paper present the competitiveness analysis of ship repair industry of Korea with the consideration of condition of location, repair cost and technological competitiveness.
송하철(H. C. Song),염재선(J. S. Yum),장창두(C. D. Jang) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The thermal elasto-plastic analysis for the prediction of welding distortion of a 3 dimensional large-scaled ship structure is a very time-consuming work since the analysis is a nonlinear problem, and a lot of finite elements are needed to simulate the large ship hull block. Generally, 3-D finite elements have been used in the 3-D welding distortion problem to assess precisely the temperature gradient through the thickness direction of the welding plate. As a result of the adoption of 3-D element, degrees of freedom are rapidly increased in the problem to be solved. In this study, to improve the time efficiency of welding thermal elasto-plastic analysis, a layered shell element was proposed to simulate 3-D temperature gradient, and the results were compared with the experiment. The experiments were carried out for the type of bead-on-plate welding, and we found the measured data have a good agreement with the FEA results.