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백대일,전정동,전우기,이성우,한창열,박수성 인제대학교 1984 仁濟醫學 Vol.5 No.4
Detecting a cholesteatoma within complicated temporal bone by simple mastoid views is desirable but any single conventional projection appears to have reached the limit of its capacity. Several simple mastoid views must be combined to delineate cholesteatoma. Author reviewed various projections of simple mastoid views in 37 cases of cholesteatomas surgically proven at Paik Hospital Inje Medical College from 1981 to 1983 in order that diagnostic value of each view could be determined. The results were as fellows: 1.Detection rate of cholesteatoma with single projection only was followings: 75% with Owen view, 60% with Towne view, 59% with Law view, 44% with Stenvers view and 33% with Transorbital magnification view. 2.Detection rate of cholesteatoma with combined projections was followings: 60% with Law, Stenvers and Towne view combination, 83% with Law, Owen and Transorbital magnification view combination. 3.Cholesteatoma involved attic in 87%, antrum in 59% and middle ear in 33%, and the combined involvement(57%) was rather frequent than single involvement (43%) 4.The mastoid air cells were poorly pneumatized in cholesteatoma, ie. sclerotic pneumatization in 81% and diploic pneumatization in 14%.
강섬유 인장강도에 따른 강섬유 보강 콘크리트 건조수축 특성
백대일,한성민,최기봉,윤현도,최원창 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.3
Much research has been conducted on steel fiber reinforced concrete (SFRC) to reduce cracks caused by drying shrinkage. Steel fiber can improve the early-age properties of concrete to increase the cracking resistance by acting as a stitch between crack faces. In this study, steel fibers with different tensile strengths were used to investigate the characteristics of drying shrinkage of SFRC. Free and restrained drying shrinkage tests were conducted, and the drying shrinkage rate was converted to the tensile strength of concrete and compared with the result of the tensile strength test. The results indicate that steel fiber has little influence on free drying shrinkage. However, for restrained drying shrinkage, as the tensile strength of steel fiber increases, it is effective in delaying the occurrence of cracks and reducing the width of cracks. In addition, steel fiber can effectively resist tensile stress caused by drying shrinkage and increases the tensile strength of SFRC, and its effectiveness increases with increasing tensile strength. 콘크리트 경화 시 발생하는 수분증발로 인한 건조수축은 콘크리트의 균열을 발생시킨다. 콘크리트에 발생하는 균열은 콘크리트의 내구성을 저하하여 안정성과 사용성에 문제를 발생시킨다. 이러한 문제점을 보안하기 위해 콘크리트에 강섬유를혼입하여 건조수축으로 인한 균열을 방지하는 강섬유 보강 콘크리트 (SFRC)에 관한 연구가 진행되고 있다. 강섬유는 콘크리트의 균열단면에서 가교역할, 부착작용을 통해 건조수축으로 인한 균열발생을 억제하고 균열 폭을 감소시키는 효과가 있다. 본 논문에서는 강섬유의 인장강도에 따른 강섬유 보강 콘크리트의 건조수축 제어성능을 평가하였다. 자유건조수축 실험과 구속건조수축 실험을 진행하였으며 실험 결과를 콘크리트의 인장응력으로 변환하여 콘크리트 직접인장실험 결과와 비교하였다. 강섬유의 자유건조수축 저감 효과는 미미하지만 강섬유의 인장강도가 증가할수록 구속건조수축으로 인한 균열제어에 효과적임을 확인하였다. 또한 강섬유의 인장강도가 증가할수록 콘크리트의 인장응력이 증가함을 확인하였다.