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증기발생기의 주기적 비파괴검사 자료와 유효POD를 이용한 물리적 결함수의 추정
이재봉(Jae Bong Lee),박재학(Jai Hak Park),김홍덕(Hong-Deok Kim),정한섭(Han-Sub Chung) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
It is necessary to know the number of flaws and their size distribution in order to calculate the probability of failure or to estimate the amount of leakage through the tube wall of steam generators. But in-service inspection (ISI) flaw data is different from the physical flaw data. In case of a single inspection, it is easy to estimate the number of physical flaws using the POD curve. However, we may be faced with some difficulties in obtaining the number of physical flaws from the periodic in-service inspection data. In this study a method for estimating the number of physical flaws from periodic in-service inspection data is proposed. In order to calculate the number of physical flaws with periodic ISI data, both probabilities of detecting and missing flaws should be considered. And flaw initiation and growth history must be known also. The flaw initiation and growth history can be inferred from appropriate probabilistic flaw growth rate. Two inference methods are proposed and compared. One is Monte Carlo simulation method and the other is transition (stochastic) matrix method. The effective POD, the total possibility of detection considering both probabilities of detecting and missing flaws for each flaw size, can be calculated using above two inference methods. And two methods are compared and the usefulness and convenience are evaluated from several applications.
Cemented type implant에서 지대치의 표면조도와 cement의 종류가 Retrievability에 미치는 영향에 관한 연구
이재봉,Lee, Jai-Bong 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.5
This study was performed to investigate the retrievability of the cementation type implant abutments. The cements used in this study were Cavitec, Tembond and Zinc Phosphate Cement. The types of surface conditioning were no treatment, 50 microne sandblasting, 250 microne sandblasting, fine diamond finishing point and coarse diamond point. The retention of cast crown was measured with Instron Universal Testing Machine(Instron Engineering Co., U.S.A.). The results were as fellows: 1. The Maximium retention was obtained by the group of Z.P.C. cementation and Coarse diamond point surface conditioning. 2. Z.P.C. shows maximum retention, and reduced in orders Tembond, Cavitec, No cement. 3. The value of retention of surface condition was highest in coarse diamond point, lowest in no tretment. 4. The similar results were obtained between fine diamond point and 50 microne sandblasting, coarse diamond point and 250 microne sandblasting. 5. The were no direct corelation between mechanical retention and cementation retention.
고정성보철물 장착환자 및 치주질환 이환자를 위한 잇솔의 식모에 관한 연구
이재봉,Lee, Jai-Bong 대한치과보철학회 1998 대한치과보철학회지 Vol.36 No.6
The purpose of this study was to investigate the ideal locations and dimensions of bristles for the patients who were installed with fixed prostheses and severely involved periodontitis. The models of 16 pts were analysed and the resullts were as follows: 1. There were no tooth brushes in the market, which were proper for the patients who were installed with fixed prostheses and had severely periodontally involved teeth. 2. The neck portion of the tooth brush should be narrow as possblly. 3. The size of tooth brush should be analyzed by the size of arch. 4. The width of tooth brush should be analyzed by the degree of bone recession. 5. The custom made tooth brush may be ideal, if possible.
임플랜트 유지 나사 머리 홈의 설계가 나사를 푸는 시간에 미치는 영향에 관한 연구
이재봉,Lee, Jai-Bong 대한치과보철학회 2002 대한치과보철학회지 Vol.40 No.2
For the purpose of decreasing the chair time in implant cases, the time needed to loosening and fastening the screw must be shortened. Nowadays, the two typical designs of screw head are slot and hexa form. This study aimed at the shortening of loosening and fastening time by modifying the slot and hexa form. Total of twelve dentists participate in these experiments, four of them were experienced and eight of them were novice dentists. 1. There were many differences in the speeds of screw loosening and fastening between personal experiences. Experienced dentists are faster than novice dentists. 2. There were many differences in the speeds by angulation of the implant, by the conditions of the muscle tonicity. 3. Revised slot and hexa Heads show the slightly shortened time for acrew looseing and fastening.
치과보철(齒科補綴) 의료(醫療) 수요(需要)에 관(關)한 연구(硏究)
이재봉,Lee, Jai-Bong 대한치과보철학회 1995 대한치과보철학회지 Vol.33 No.1
A total of 2,510 police personnel aged 20-59 were examined to determine the prosthodontic demands. The results were as follows. 1. Prosthodontic demands increase with aging. 2. Periodontic problem is the major cause of the prosthodontic needs in old personnel. 3. Trauma is the more popular cause of the prosthodontic need than periodontal problem in policeman. 4. The major cause of the untreatment is the lacks of time. 5. The younger persons have more fear of dental treatment. 6. Prostodontic demands show declining trends.
이재봉(Jae Bong Lee),김민철(Min-Chul Kim),박재학(Jai Hak Park),이봉상(Bong Sang Lee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
In this study a relationship between SP curves and tensile properties was investigated by FE analysis on SP<br/> test with various assumed tensile properties. For the accuracy of FE analysis, SP test and tensile test were<br/> performed and those results were compared with FE analysis results. The yield load(Py) defined from the<br/> intersection point of two lines tangent to the elastic bending region and plastic bending region. And it was<br/> related specifically with yield stress(σ0) in FE analysis result curves. The slopes of FE analysis result curves<br/> normalized by yield stress(σ0) reflected the change of tensile properties regardless of yield stress(σ0)<br/> variation. Empirical relations were derived from these results. Tensile properties from these relations showed<br/> good agreement in FE analysis curve and tested curve.