기질레진의 조성에 따른 복합레진의 물리적 성질에 관한 연구

이연신,최경구,박상진 大韓齒科保存學會 2002 Restorative Dentistry & Endodontics Vol.27 No.1

Current composites are made with dimethacrylate monomers and silane-treated silica microfillers, either alone or with silane treated glass fillers. The main reasons for clinical failure of dental composites are secondary caries, wear and fracture. Most of practitioner want to get a composite which is more tougher under occlusal stress, less polymerization contraction, and better handling properties in application clinically. The aim of this study was to investigate the influence of resin matrix with various flows on the physical properties such as facture toughness and degree of conversion of the experimental resins. It was hypothesized that flexible or tough resin compoties can be designed by judicious choice of monomer comptosition Various flow resin matrices containing Bis-GMA, UDMA, and TEG-DMA were made by altering the proportion of the monomers. After the unfilled resins were light-cured for different light intensity. the fracture toughness(K_1c) was measured according to ASTM standard using the the single edge notched geometry, and degree of conversion(DC) was measured by FTIR. And experimental composites were formulated with variations in the proportion of silanated quartzz and strontium glass fillers as 60, 75, and 77wt%. Also, the physical properties of composites with various filler contents were evaluated as same manner. All resulting data were compared by ANOVA/Tukeys test at 0.05 level. The results were as follows; 1. The degree of conversion of high flow resin containing less Bis-GMA was higher than that of low flow unfilled resin. 2. While the degree of conversion of unfilled resin was increased according to light intensity for polymerization, there was no significant increase with moderate and high light intensity. Also, the fracture toughness was not increased by high light intensity 3. The fracture toughness was high in the flow unfilled resin containing higher contents of Bis-GMA. 4. There was a significant increase for fracture toughness and a tendency for degree of conversion to be reduced when the content of fillers was increased. 5. In the experimental composites, the flow of resin matrix did not affected on the fracture toughness, even, which was decreased as increase of viscosity. These results showed that the physical properties of a dental composite could be attributed to the flow of resin matrix with relative content of monomers. Specific combination of resin monomers should be designed to fulfill the needs of specific indication for use.

현장맞춤형 선박해양 교과과정 개선에 관한 연구

이연신,김항우,한재호 한국공학교육학회 2012 공학교육연구 Vol.15 No.6

In this paper, we present, based on a systematic job analysis, the definition, flowchart and description of Ship Building & Ocean Engineering Technician’s job in Ship Building & Ocean Engineering Industry for developing an Ship Building & Ocean Engineering education and training program in the context of Korea situation. In addition, it is suggested that the courses be directed toward job site-centered reform through conducting job analysis with experts in the environmental industry. serving new courses demanded by industries in practice and providing training programs for industries.

압력용기 구조물 용접부에서 잔류응력이 피로균열진전거동에 미치는 영향

이연신,차용훈,김덕중,성백섭 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2

This paper is to investigated the influence of welding residual stresses on the fatigue crack growth behaviors in the vertical direction to the weld bead. So, Co₂Automatic welding was performed on the ASTM A5l6 grade 60 Steel. For skip and continuous fillet welding, the specimens of fatigue cracks are initiated at toe end and beginning of welded specimen. The fatigue life of continue fillet welding is greater then that of skip fillet welding. The fatigue lief of as welded specimen is longer than that of PWHT specimen because the compression residual stress are greater than the other zone, which are near the welding toe notch of welded specimen. For skip and continuous fillet welding, da/dN-ΔK relations show retardation at HAZ and increase linearly at the stable growth region.

현장맞춤형 선박해양 교과과정 개선에 관한 연구

이연신(Youn-Sin Lee)김항우(Hang-Woo Kim),한재호(Jae-Ho Han) 한국공학교육학회 2012 공학교육연구 Vol.15 No.6

In this paper, we present, based on a systematic job analysis, the definition, flowchart and description of Ship Building & Ocean Engineering Technician’s job in Ship Building & Ocean Engineering Industry for developing an Ship Building & Ocean Engineering education and training program in the context of Korea situation. In addition, it is suggested that the courses be directed toward job site-centered reform through conducting job analysis with experts in the environmental industry. serving new courses demanded by industries in practice and providing training programs for industries.

공학기술교육인증 프로그램의 효과적인 운영 사례에 관한 연구

이연신(Youn-Sin Lee),한재호(Jae-ho Han),김항우(Hang-Woo Kim) 한국공학교육학회 2016 공학교육연구 Vol.19 No.2

An engineering educational servery for graduating seniors had been conducted in Songwon University to improve engineering program objectives. The analysis results show that the current engineering educational objectives need to be modified to satisfy the ABEEK accredited criteria and engineering curriculum returning is necessary to include more design courses.

신경회로망을 이용한 맞대기 용접부의 잔류응력 예측에 관한 연구

차용훈,이연신,성백섭 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.2

In order to achieve effective prediction of residual stresses, the series experiment were carried out and measured the residual stresses using the backpropagation algorithm from the neural network and the sectional method. Using the experimental results, the optional control algorithms using a neural network should be developed in order to reduce the effect of the external disturbances on during GMA welding processes. Then the results obtained from this study showed that through comparison between the measured and calculated results, the neural network based on backpropagation algorithm might be controlled weld quality. This system can not only help to understand the interaction between the process parameters and residual stress, but also, improve the quantity control for welded structures.

신경회로망을 이용한 용접잔류응력 예측 및 최적의 용접조건 선정에 관한 연구

차용훈,이연신,성백섭 한국안전학회 2001 한국안전학회지 Vol.16 No.5

In this study, it is developed that the system for effective prediction of residual stresses by the back-propagation algorithm using the neural network. To achieve This goal, the series experiment were carried out and measured the residual stresses using the sectional method. Using the experimental results, the optional control algorithms using a neural network should be developed in order to reduce the effect of the external disturbances during GMA welding processes. Then the results obtained from this study were compared between the measured and calculated results, weld guality might be controlled by the neural network based on backpropagation algorithm. This system can no only help to understand the interaction between the process parameters and residual stress, but also improve the quantity control for welded structures.

근골격계 질환 예방을 위한 재생타이어 트레드 버핑머신 개발

김재열,한재호,이연신,김항우,오성민 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-

As a part of environmental pollution prevention and resources recycling, the regeneration of waste tire has been largely contributed to national industry. But, the worker has been evaded this regeneration process by reason of the best mischievous process condition among 3D industries.So, the first, the process condition of regeneratingwaste tire was analyzed. The second, the equipment or system was developed for the improvement of working strength and environment. The last, researchers intend to solve these problems

임의의 비드형상을 의한 최적의 공정변수 예측 알고리즘 개발에 관한 연구

김일수,차용훈,이연신,박창언,손준식 대한용접접합학회 1999 대한용접·접합학회지 Vol.17 No.4

The procedure of robotic Gas metal Arc (GMA) welding in order to achieve the optimized bead geometry needs the selection of suitable process parameters such as arc current, welding voltage, welding speed. It is required the relationships between process parameters and bead geometry. The objective of this paper is to develop the algorithm that enables the determination of process parameters from the optimized bead geometry for robotic GMA welding. It depends on the inversion of empirical equations derived from multiple regression analysis of the relationships between the process parameters and the bead dimensions using the least square method. The method not only directly determines those parameters which will give the desired set of bead geometry, but also avoids the need to iterate with a succession of guesses employed Finite Element Method(FEM). These results suggest that process parameter from experimental equation for robotic GMA welding may be employed to monitor and control the bead geometry in real time.

트스트랜드 강화 ALS 계 복합재료의 파괴인성 평가

차용훈,김덕종,이연신,성백섭,채경수 한국산업안전학회 1998 한국안전학회지 Vol.13 No.1

It is well known in the fracture mechanics community that the fracture toughness of brittle materials, such as ceramics, can be improved improves significantly when fibers are added into the material. This is because in presence of fibers the cracks cannot propagate as freely as it can in absence of them. Fibers bridge the gap between two adjacent surfaces of the crack and reduce the crack tip opening displacement, thus make it harder to propagate. Several investigators have experimentally studied how the length, diameter and volume fraction of fibers affect the fracture toughness of chopped strand reinforced matrix composite materials. In this paper, matrix used ALS, Arizona Lunar Simulant, types of fiber used carbon steels and stainless steels. To analyze quantitatively fiber reinforced ALS composites, experimental and analytical methods was progressed. Load-displacement curve is used to experimental method, and FEM analysis program using ABAQUS is used analytical method.