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임정숙(Jeong Suk Lim),유기한(Ki Han Yu),정원지(Won Jee Chung),김수태(Soo Tae Kim),이정환(Jung Hwan Lee),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.7
Thermal displacement of high speed spindle is very important problem to be solved. To solve heat generation and thermal displacement problems that influence on the product accuracy, it is very important to predict thermal characteristics of the spindle and it is positively necessary to select the conditions of cooling, flow rate and preload of bearings. In this paper, 30,000rpm(1.455×10?DmN) spindle was designed and produced. The analysis of thermal deformation for heat generation of inner spindle was carried out using commercial program ANSYS<SUP>®</SUP> and the result was compared with measured data using LabVIEW<SUP>®</SUP> and SCXI-1600, 1125 and 1126 module. Temperature distribution and thermal displacement according to spindle speed are measured. Using this method, it is possible to predict and to improve thermal characteristic of high speed spindle by control spindle speed, bearing preload and cooling rate.
정신보건 사회복지사의 이차적 외상스트레스가 직무만족에 미치는 영향 자아탄력성과 사회적 지지의 조절효과
임정숙(Jeong Suk Lim),윤명숙(Myeong Sook Yoon) 한국정신건강사회복지학회 2014 정신보건과 사회사업 Vol.42 No.1
본 연구는 정신보건 사회복지사가 직무수행과정에서 클라이언트의 외상에 노출됨으로써 경험하는 이차적 외상스트레스의 발생과 이차적 외상스트레스가 직무만족에 미치는 관계를 살펴보고, 이 관계에 영향을 미치는 자아탄력성과 사회적 지지의 조절효과를 검증하기 위한 연구이다. 이를 위해 4개 지역 38개소의 정신건강증진센터에 근무하는 정신보건 사회복지사 284명을 대상으로 조절회귀식을 이용하여 분석하였다. 연구결과, 첫째, 정신보건 사회복지사의 이차적 외상스트레스는 직무만족에 유의미한 영향을 미치는 것으로 나타났다. 둘째, 이차적 외상스트레스와 직무만족의 관계에서 자아탄력성이 조절효과를 가지는 것으로 나타났다. 셋째, 이차적 외상스트레스와 직무만족의 관계에서 사회적 지지는 유의미한 조절효과가 나타나지 않았다. 이러한 연구결과를 바탕으로 정신보건 사회복지사의 이차적 외상스트레스 문제에 개입하고 정신보건 사회복지사의 직무만족도를 높이기 위한 방안과 후속 연구들을 제언하였다. The purpose of this study was to investigate moderating effects of ego-resilience and social support between secondary traumatic stress and job satisfaction among mental health social workers. Data were collected from 285 mental health social workers who were working at 38 community mental health center. Collected data were analyzed by frequency, t-test, moderated multiple regression and simple slope analysis. The major findings of this study were as follows: First, secondary traumatic stress were significantly related to the job satisfaction. Second, ego-resilience and social support were significantly related to the job satisfaction. Third, ego- resilience moderated between secondary traumatic stress and job satis-faction among mental health social workers. But social support showed no moderating role between secondary traumatic stress and job satisfaction among mental health social workers. These findings supported the importance of secondary traumatic stress program and self-care program in mental health field. Suggestions of mental health social worker were discussed.
드로우바와 로터가 고속주축계의 동적 특성에 미치는 영향
임정숙(Jeong-Suk Lim),정원지(Won-Jee Chung),이춘만(Choon-Man Lee),이정환(Jung-Hwan Lee) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.3
The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. For more quantitative analysis of a built-in motor's dynamic characteristics, that of the mass and stiffness effects are considered. And the drawbar in the spindle can be in various condition according to supporting stiffness between drawbar and shaft. Therefore, in this paper following items are performed and analyzed : 1. Modal characteristics of the spindle. 2. Analysis of rotor's mass and stiffness effects. 3. Modal characteristics of the spindle including drawbar, rotor and tool. The results show enough stiff supports must be provided between shaft and drawbar to prevent occurring drawbar vibration lower than the natural frequency of 1st bending mode of the spindle, and considering the mass and stiffness of built-in motor's rotor is important thing to derive more accurate results.
임정숙(Lim Jeong-Suk),정원지(Chung Won-Jee),이춘만(Lee Choon-Man),이정환(Lee Jung-Hwan) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.2
The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. To improve the competition power of price to quality, spindle design is very important. Because it possesses over 10 percent of machine tool's price. The latest machine tools have rotational frequency and excellent about might and precision cutting. So it requires static and dynamic strength in the load aspect. In conclusion, the deformation of the spindle end have to extremely small displacement in static and dynamic load. In this study, On the assumption that the bearings that are supporting 24,000rpm high-speed spindle are selected in the most optimum condition, the natural frequency and deformation of the spindle end is obtained by FEM mode analysis. The Taguchi Method was used to draw optimized condition of bearing position and it's stiffness.
40,000rpm 고속 주축의 정ㆍ동특성 향상을 위한 베어링 위치 선정
임정숙(Jeong Suk Lim),정원지(Won Jee Chung),이춘만(Choon Man Lee) 한국기계가공학회 2009 한국기계가공학회지 Vol.8 No.1
Spindle design is very important for the improvement of the competitive power in production cost of high quality machine tools. The important factor in spindle design is not only to improve the natural frequency of spindle but also to reduce displacement of spindle end. In this paper, parameters those influence on static and dynamic stiffness of high-speed spindle have selected form preceding studies. And those selected parameters are applied to Taguchi Method. To perform FEM analysis, bearing conditions are selected with optimized condition. To know how to improve static and dynamic stiffness of machine tool spindle, natural frequency and displacement of spindle end are obtained by FEM analysis. The Taguchi Method was used to draw optimized condition of bearing position and it's stiffness. From these results, amplitude of vibration is enough good less than 3㎛ pk-pk of the spindle of 40,000rpm manufactured in this work by the optimal design.
미세 볼엔드밀가공시 절삭력과 음향방출신호에 의한 공구 파손 검출 및 메커니즘
왕덕현,김원일,임정숙,Wang, Duck-Hyun,Kim, Won-Il,Lim, Jeong-Suk 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.3
A successful on-line monitoring system for conventional machining operations has the potential to reduce cost, guarantee consistency of product quality, improve productivity and provide a safer environment for the operator. In fine-shape machining, typical signs of tool problems such as vibration, noise, chip flow characteristics and visual signs are almost unnoticeable without the use of special equipment. These characteristics increase the importance of automatic monitoring in fine-shape machining, however, sensing and interpretation of signals ar more complex. In addition, the shafts of the mini-tools break before the typical extensive cutting edge of the tool gets damaged. In this study, the existence of a relationship between the characteristics of the cutting force and tool usage was investigated, and tool breakage detection algorithm by LabVIEW was developed and the following results are obtained. It was possible to use a relative error compare which mainly used in established experiment and investigated tool breakage detection algorithm in time domain which can detect AE and cutting force signals more effective and accurate.