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STUDY OF RCM-BASED MAINTENANCE PLANNING FOR COMPLEX STRUCTURES USING SOFT COMPUTING TECHNIQUE
손영탁,김배영,박기준,이호용,서명원,김현준 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.5
To guarantee the efficiency of maintenance strategies for a complex structure, safety and cost limitations must be considered. This research introduces RCM-based (Reliability Centered Maintenance) life cycle optimization for reasonable maintenance. The design variable is the reliability of each part, which consists of a complex structure, while the objective is to minimize the total cost function in order to maintain the system within the desired system reliability. This research constructs the cost function that can reflect the current operating condition and maintenance characteristics of individual parts by generating essential cost factors. To identify the optimal reliability of each component in a system, this paper uses a Neuro-Evolutionary technique. Additionally, this research analyzes the reliability growth of a system by using the AMSAA (Army Material Systems Analysis Activity) model to estimate the failure rate of each part. The MTBF (Mean Time Between Failure) and the failure rate of the whole system, which is responding to the individual parts, are estimated based on the history data by using neural networks. Finally, this paper presents the optimal life cycle of a complex structure by applying the optimal reliability and the estimated MTBF to the RAMS (Reliability, Availability, Maintainability, and Safety) algorithm. To guarantee the efficiency of maintenance strategies for a complex structure, safety and cost limitations must be considered. This research introduces RCM-based (Reliability Centered Maintenance) life cycle optimization for reasonable maintenance. The design variable is the reliability of each part, which consists of a complex structure, while the objective is to minimize the total cost function in order to maintain the system within the desired system reliability. This research constructs the cost function that can reflect the current operating condition and maintenance characteristics of individual parts by generating essential cost factors. To identify the optimal reliability of each component in a system, this paper uses a Neuro-Evolutionary technique. Additionally, this research analyzes the reliability growth of a system by using the AMSAA (Army Material Systems Analysis Activity) model to estimate the failure rate of each part. The MTBF (Mean Time Between Failure) and the failure rate of the whole system, which is responding to the individual parts, are estimated based on the history data by using neural networks. Finally, this paper presents the optimal life cycle of a complex structure by applying the optimal reliability and the estimated MTBF to the RAMS (Reliability, Availability, Maintainability, and Safety) algorithm.
5-FU 투여후 백서 가슴샘에서 일어나는 형태학적 및 생화학적 변화
손영탁,김선,정옥,한승로,김수일,이영호,김원식 충남대학교 의과대학 지역사회의학연구소 2000 충남의대잡지 Vol.27 No.2
Thymus is a lymphoid organ forming T-cells from hematogenous stem cells. Apoptosis of thymocytes in the cortex of thymus is so rapid that cannot find easily with routine histological techniques. In this experiment, TUNEL immunohistochemistry and TEM were used to detect apoptotic changes after 5-fluorouracil treatment in the thymus of the rat. In addition, SDS-PAGE was carried to reveal protein changes along the apoptotic changes. The results were as follows ; 1. Thymocytes in the cortex were decreased markedly and many apoptotic cells were found in the cortex on DAT 3. 2. Relatively small-sized apoptotic bodies induced by 5-FU were detected on DAT 3 at the cortex, and clustered in partly. 3. On DAT 6, new germinal centers formed in the peripheral cortex, and many apoptotic bodies of various size and shapes were detected in the germinal center. 4. In SDS-PAGE, a protein with molecular weight of 123kDa was increased on DAT 6. According to the above results, it could be concluded that 5-FU acted directly on the thymocytes and induced apoptotic changes on DAT 3. But, on DAT 6, the period of recovery, new germinal centers were formed in the cortex, in which active B cell production to compensate the loss of thymocytes was noticed. To make new T-cells from B-cells and to eliminate unnecessary B-cells, vigorous apoptosis in the germinal centers should occur, and 123kDa proteins which considered as integrins should act as transmembrane signaling molecules in this process.
치과용 레이저 및 임플란트 엔진 시스템의 사용자 만족도 비교 연구
손영탁,손큰바다,이재목,유원재,김진욱,이규복 대한통합치과학회 2022 대한통합치과학회지 Vol.11 No.3
The purpose of this study was to compare the performance of each system by examining the satisfaction of dentists with dental laser and implant engines. 21 dentists at Kyungpook National University dental hospital and the dental clinic in Daegu were selected. A multi-type laser and implant engine system (BLP10/CRB46LN/LSR20NN, Saeshin, Daegu, Republic of Korea), an implant engine system (SurgicPro+/X-DSG20L, NSK, Kanuma, Japan), and a laser engine system (Epic 10/surgical handpiece 6400479, Biolase, Irvine, USA) were used for evaluation. The survey was conducted with 10 items for the implant system and 9 items for the laser system. The blind test was conducted without providing product information. After using each product, the questions were evaluated using a 5-point Likerttype scale and the satisfaction of the dentist was quantified. The statistical significance for product comparison was evaluated using the Kruskal-Wallis test (α=0.05). In the user satisfaction of the implant engine system, there was a significant difference when comparing Saeshin product and NSK product in ‘Cutting force when forming holes’ and ‘Fixability of the drill’ of functional items (P<0.05). In the user satisfaction of the laser engine system, there was a significant difference when comparing Saeshin product and Biolase product in ‘Adequacy of output during soft tissue incision’, ‘Ease to attachment and detachment of laser tip’, ‘Convenience of adjusting the angle of the laser tip’ of functional items (P<0.05). There was a significant difference in ‘Adequacy of handpiece weight’ and ‘Detachable method of laser tip’ in items for laser handpiece design (P<0.05). Each system had a significant difference in satisfaction with function and handpiece design, and improvements for each system could be observed.