• 한국공작기계학회논문집
• /
• 제16권4호
• /
• pp.45-50
• /
• 2007

In this paper, the FEM(Finite Element Method) has been applied to understand the geometrical characteristics and to analyze the stress of a helical gear. The helical gear is simulated and analyzed by adding many thin spur gear with helix angles and twist angles. Helical gears with different helix angle and face width have been studied. The results show that the root fillet stress is increased proportionally to helix angle and face width. Namely, as the face width increases, root fillet stress decreases, and as helix angle gets bigger, root fillet stress increases.

• 한국공작기계학회논문집
• /
• 제11권3호
• /
• pp.110-116
• /
• 2002

Here are shown on stress and vibration evaluations and application of piping system in petrochemical plant with and actual example. While stress evaluation by thermal growth has no argument on the calculated results, vibrational evaluations have some different results in accordance with the evaluation methods. In case of the static stress evaluation the ASME B3l.3 code defines 7000 cycles of fatigue lift: in operating the piping system with a design condition. However, the method of vibrational evaluation on piping systems in petrochemical plants has not been established clearly, yet. In this stuffy, it is purposed to present the requirement of a vibrational evaluation method for petrochemical plant piping system, with an actual application.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
• /
• pp.380-385
• /
• 2000

In this study, geometric shape and crack in welded interface of the air cooled heat exchanger Fin-Tube of Dissimilar Meterials was analysed. The object of study is to understand the behavior of Stress Intensity Factor for fin length, flash thickness, flash length, symmetric and asymmetric cracks of comming from the manufacturing process. Stress Intensity Factor was analysed by BEM. Kelvin's solution was used as a fundamental solution in BEM analysis and stress extrapolation method was used to determine Stress Intensity Factor.

• 대한기계학회논문집A
• /
• 제26권10호
• /
• pp.2211-2218
• /
• 2002

In this study, an optimal design study has been made to determine dimensions of die and multi stress rings for extrusion process. For this purpose, a thermo-rigid-viscoplastic finite element program, CAMPform, was used fur forming analysis of extrusion process and a developed elastic finite element program fur elastic stress analysis of the die set including stress rings. And an optimization program, DOT, was employed for the optimization analysis. From this investigation, it was found out that the amount of shrink fitting incurred by the order of assembly of the die set should be taken into account for optimization when the multi stress rings are used in practice. In addition, it is construed that the proposed design method can be beneficial fur improving the tool life of cold extrusion die set.

• 대한기계학회논문집A
• /
• 제30권8호
• /
• pp.873-879
• /
• 2006

To investigate applicability of the reference stress approach as simplified inelastic stress analysis to estimate local creep rupture, detailed finite element stress analyses of a T-piece pipe with different inner pressure and system loading levels are performed. The reference stresses are obtained from the finite element (FE) limit analysis based on elastic-perfectly-plastic materials, from which the local reference stress for creep rupture is determined from R5. The resulting inelastic stresses are compared with elastic stresses resulting from linear elastic FE calculations. Furthermore they are also compared with the stresses from full elastic-creep FE analyses. It shows that the stresses estimated from the reference stress approach compare well with those from full elastic-creep FE analysis, which are significantly lower than the elastic stress results. Considering time and efforts for full inelastic creep analysis of structures, the reference stress approach is shown to be a powerful tool for creep rupture estimates and also to reduce conservatism of elastic stress analysis significantly.

• 한국문헌정보학회지
• /
• 제47권3호
• /
• pp.181-205
• /
• 2013

이 연구는 대학도서관 사서들이 업무수행 과정에서 받고 있는 직무스트레스를 보다 정확하게 측정할 수 있는 척도를 개발하고자, 실증연구를 통하여 기존의 국내 외 대표적 직무스트레스 척도를 분석하여 종합하고, 질적 연구방법 중 심층면접법을 도입하여 대학도서관 사서가 가지고 있는 특징적인 스트레스 요인을 추적하였다. 또한 두 척도를 종합한 직무스트레스 척도의 신뢰도와 타당도에 대한 분석을 실행하였다. 그 결과 '동료관계 갈등요인', '상하관계 갈등요인', '업무보상 평가요인', '감정노동 요인', '물리적 환경요인', '고용안정성', '심리적 직무요구요인', '의사결정 및 책임요인', '업무복잡성 요인', '업무경계 갈등요인', 그리고 '신체적 직무요구요인' 등 11개 요인, 46개 문항으로 구성된 사서를 위한 직무스트레스 척도가 개발되었다.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 추계학술대회 논문집
• /
• pp.98-107
• /
• 2004

The objectives of this research are to establish the criteria of peel occurrence considering the shape of bond terminus and to compare the strength properties of some adhesive joints. The criteria of feel occurrence at the bond terminus was suggested. Peel loads of some adhesive joint(butt joint, T -shape specimen, single lap joint) were determined from tensile tests. Principal stress distributions of these joints were determined from finite element method analysis. Then, peel occurrence was estimated with intensity of stress singularity ' $K_{prin.}$' when the terminus shape was square, with average principal stress when the terminus shape was rounded. The conclusions are summarized as follows; (1) In the non-filleted model(e.g., butt joint, T-shape specimen), principal stress shows singularity at the bond terminus, intensity of stress(principal stress) singularity ' $K_{prin.}$&apso; can use as the criteria of peel occurrence at the bond terminus. (2) In the filleted model(e.g., single lap joint), principal stress doesn't show singularity at the bond terminus. Average principal stress can use as the criteria of peel occurrence at the bond terminus.'t show singularity at the bond terminus. Average principal stress can use as the criteria of peel occurrence at the bond terminus.

• The Journal of Korean Physical Therapy
• /
• 제22권1호
• /
• pp.83-90
• /
• 2010

Purpose: This study aimed to determine the degree of job stress and self-esteem of physical therapists as well as the correlation between the two variables. Method: This study targeted 218 physical therapists of Busan City, and was carried out from July 16 to August 6, 2009 as survey research. A structured questionnaire referring to advance researches was used as a research tool. Job stress symptoms were measured one a 5 point scale, the higher the point total, the higher the job stress. Self-esteem was measured on a 4 point scale, the higher the point total, the lower the self-esteem. After data collection we determined descriptive statistics, and did reliability analysis, factor analysis, Spearman's correlation analysis, and regression analysis. Results: Reliability analysis indicated that reliability for the job stress questionnaire was 0.93 and for the self-esteem was 0.83. The average job stress score of physical therapists was 1.19 points which was not high. The average self-esteem score was 1.76 points, whichwas high. It appeared that the higher the self-esteem, the lower the job stress. Also, self-esteem had an influence on psychological symptoms among job stress factors. Conclusion: Job stress and self-esteem of physical therapists are well-correlated and influence each other. Accordingly, self-esteem can be used as a variable for adjusting job stress of physical therapists.

• 대한간호학회지
• /
• 제38권3호
• /
• pp.410-419
• /
• 2008

Purpose: The purpose of this study was to develop a stress measurement scale for Korean nursing students. Methods: Sixty preliminary items were selected by classifying 229 basic items extracted via literature review and Q-sorting method. In order to verify the reliability and validity of the preliminary instrument, data were collected from 617 nursing students in 2 colleges of nursing in Korea. Results: As a result of the item analysis, 58 items were selected. They consisted of 2 types of stress which were college-based stress (38 items) and clinical-based stress (20 items). Ten factors in college-based stress and four factors in clinical-based stress were extracted by factor analysis, and each had a total variance of 63.01%, and 64.93%. Cronbach's Alpha of those 58 items were .937 in college-based stress and .922 in clinical-based stress, which was high. Conclusion: This paper is meaningful in a way that it has developed a tool capable of measuring stress for nursing students, which reflects the characteristics of our country. It is recommended for further study to re-verify the relevance and stability of this measurement.

• 한국기계가공학회지
• /
• 제17권6호
• /
• pp.1-6
• /
• 2018

Recently nano meter size pattern (sub-micro scale) can be machined mechanically using a diamond tool. Many studies have found a 'size effect' which referred to a specific cutting energy increase with the decrease in the uncut chip thickness at micro scale machining. A new analysis method was suggested in order to observe 'size effect' in nano scale machining and to verify the cause of the 'size effect' in this study. The diamond tool was indented to a vertical depth of 1,000nm depth in order to simplify the stress state and the normal force was measured continuously. The tip rounding was measured quantitatively by AFM. Based on the measurements and theoretical analysis, it was verified that the main cause of the 'size effect' in nano scale machining is geometrically necessary dislocations, one of the intrinsic material characteristics. st before tool failure.