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오일석(I.-S. Oh),김동주(D. Kim),우마로프 알리세르(A. Umarov),곽호상(H.S. Kwak),김경진(K. Kim) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.4
A modern optical fiber manufacturing process requires the sufficient cooling of glass fibers freshly drawn from the heated and softened silica preform in the furnace, since the inadequately cooled glass fibers are known to cause improper polymer resin coating on the fiber surface and to adversely affect the product quality of optical fibers. In order to greatly enhance the fiber cooling effectiveness at increasingly high fiber drawing speed, it is necessary to use a dedicated glass fiber cooling unit with helium gas injection between glass fiber drawing and coating processes. The present numerical study features a series of three-dimensional flow and heat transfer computations on the cooling gas and the fast moving glass fiber to analyze the cooling performance of glass fiber cooling unit, in which the helium is supplied through the discretely located rectangular injection holes. The air entrainment into the cooling unit at the fiber inlet is also included in the computational model and it is found to be critical in determining the helium purity in the cooling gas and the cooling effectiveness on glass fiber. The effects of fiber drawing speed and helium injection rate on the helium purity decrease by air entrainment and the glass fiber cooling are also investigated and discussed.
광섬유 고속생산용 헬륨 주입식 유리섬유 냉각공정에 대한 열유동 해석
오일석(I.-S. Oh),김동주(D. Kim),곽호상(H.S. Kwak),김경진(K. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
In manufacturing optical fibers, the process starts with the glass fiber drawing from the heated and softened silica preform in the furnace, and the freshly drawn glass fiber is still at high temperature when it leaves the glass fiber drawing furnace. It is necessary to cool down the glass fiber to the ambient temperature before it then enters the fiber coating applicator, since the hot glass fiber is known to cause several technical difficulties in achieving high quality fiber coating. As the fiber drawing speed keeps increasing a current manufacturing of optical fibers requires a dedicated cooling unit with helium gas injection. A series of three-dimensional flow and heat transfer computations are carried out to investigate the effectiveness of fiber cooling in the fiber cooling unit. The glass fiber cooling unit is simplified into the long cylindrical enclosure at which the hot glass fiber passes through at high speed, and the helium is being supplied through several injection slots of rectangular shape along the cooling unit. This study presents and discusses the effects of helium injection rates on the glass fiber cooling rates.
김수형(S. H. Kim),정선화(S. W. Jeong),오일석(I. S. Oh) 한국정보과학회 1998 한국정보과학회 학술발표논문집 Vol.25 No.2Ⅱ
본 논문에서는 필기 한글 문자의 오프라인 인식 기술에 관련하여 최근 5년 동안 발표된 연구 사례를 종합하여 향후의 연구자들이 연구 방향을 설정하고 방법론을 개발하는데 도움이 되도록 함은 물론, 당 분야 연구의 발전 방향을 모색하고자 한다. 사례 조사의 범위는 필기 한글 문자 인식에 관련된 문자 데이터베이스, 날자 인식, 단어 인식의 세 가지 핵심 요소 기술로만 국한하였으며 이들 각각에 대한 향후 연구의 방향을 제시하였다.