• 한국정밀공학회지
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• 제17권11호
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• pp.199-205
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• 2000

The vibration and noise of gears is due to the vibration exciting force caused by the tooth stiffness which changes periodically as the mesh of teeth proceeds and by the transmission error, that is, the rotation delay between driving gear and driven gear caused by manufacturing error and alignment error in assembly and so on. The purpose of this study is to develop how to calculate simultaneously the optimum amounts of tooth profile modification, end relief and crowning by minimizing the vibration exciting force of helical gears. We estimate the vibration exciting force by the mesh analysis of gears. The constraints of this problem consist of contact ratio and strengths of gear teeth such as tooth fillet stress, surface durability and scoring. ADS(Automated Design Synthesis) is used as an optimization tool. And, since the aspect ratio is an important parameter of tooth modification, we investigate the relation between it and the optimum values of tooth modification. The proposed method can calculate the optimum amount of tooth modification automatically and is to be utilized to resolve the problem of vibration of helical gears.

• Journal of Welding and Joining
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• 제15권6호
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• pp.66-77
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• 1997

In the present work, Taguchi method for electron beam welding(EBW) process in AISI 4130 steel plate has been adopted for investigating the contribution of effect of welding variables. $A L_8(2^7)$ orthogonal array is adopted to obtain the effect of adjustment parameters. The adjustment parameters consist of accelerating voltage, beam current, travel speed and focus currrent. And the quality features selected for the EBW process are bead width of weldment, reinforcement, penetration depth, undercut and area of weld metal. Variance analysis is performed in order to check the effect of adjustment parameters on EBW. The mechanical properties of electron beam welded joints for each heat treatment conditions are investigated in comparison with those of base metal, especially from the view point of tensile and impact properties.

• 기본간호학회지
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• 제20권4호
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• pp.419-428
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• 2013

Purpose: This study was done to explore the level of life stress, depression, and suicidal ideation and to identify the associated factors of suicidal ideation (SI) among college nursing students. Method: The design of this study was a descriptive survey design using a convenience sampling. Data collection was done using self-questionnaire from 124 students in 2 universities located in Gyeonggi and Chungnam provinces. The collected data were analyzed using descriptive statistics, ANOVA, t-test, Pearson correlation coefficients, and hierarchical multiple regression. Results: Study participants reported low level of SI, depression, and life stress ($44.45{\pm}19.21$, $8.40{\pm}5.94$, $40.65{\pm}32.17$). The 53% of variance in SI was significantly explained by life stress related value (${\beta}=.41$, p<.001), life stress related to interpersonal relationship with family (${\beta}=.19$, p=.014), life stress related to interpersonal relationship with friends (${\beta}=.34$, p<.001), and depression (${\beta}=.36$, p<.001). Conclusions: The results indicate that to decrease the SI in these students, an active interest in the students is needed to lower stress levels in interpersonal relationships with family and friends, in life stress related to value, and for relief of depression. Suicide prevention programs specific to the level of life stress and depression need to be developed for nursing students.

• 한국재료학회지
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• 제23권1호
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• pp.18-23
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• 2013

In this study, the effects of cryogenic treatment cycles on the residual stress and mechanical properties of 7075 aluminum alloy (Al7075) samples, in the form of a tube-shaped product with a diameter of 500 nm, were investigated. Samples were first subjected to solution treatment at $470^{\circ}C$, followed by cryogenic treatment and aging treatment. The residual stress and mechanical properties of the samples were systematically characterized. Residual stress was measured with a cutting method using strain gauges attached on the surface of the samples; in addition, tensile strength and Vickers hardness tests were performed. The detailed microstructure of the samples was investigated by transmission electron microscopy. Results showed that samples with 85 % relief in residual stress and 8% increase in tensile strength were achieved after undergoing three cycles of cryogenic treatments; this is in contrast to the samples processed by conventional solution treatment and natural aging (T4). The major reasons for the smaller residual stress and relatively high tensile strength for the samples fabricated by cryogenic treatment are the formation of very small-sized precipitates and the relaxation of residual stress during the low temperature process in uphill quenching. In addition, samples subjected to three cycles of cryogenic treatment demonstrated much lower residual stress than, and similar tensile strength compared to, those samples subjected to one cycle of cryogenic treatment or artificial aging treatment.

• 스트레스연구
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• 제25권4호
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• pp.239-245
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• 2017

본 연구는 아로마테라피 족욕이 스트레스와 자율신경계의 활성도에 미치는 효과를 비교하기 위한 연구이다. 실험 처치로 아로마테라피 족욕 군에게는 에센셜 오일 라벤더, 레몬, 티트리를 6:3:1의 비율로 혼합한 후 18 L의 물에 0.5 cc 떨어뜨려 족욕을 하도록 하였고, 족욕 군은 물로만 족욕을 하도록 하였다. 연구결과로 아로마테라피 족욕은 주관적 스트레스 점수(t=3.465, p=0.001), 스트레스 지수(t=3.021, p=0.004)가 유의하게 감소하였으며, 교감신경 활성도는 아로마테라피 족욕 군이 더 유의하게 증가하였고(t=-2.913, p=0.005), 부교감신경 활성도는 유의한 차이가 나타나지 않았다(t=-1.831, p=0.072). 결론적으로 아로마테라피 족욕과 족욕 모두 스트레스를 완화하는 데 효과적이었으며 그 중 아로마테라피 족욕이 스트레스를 더 완화했다. 그러므로 아로마테라피 족욕이 스트레스 감소를 위한 효과적인 중재가 될 수 있으므로, 건강한 성인뿐만 아니라 간호 대상자의 스트레스 감소를 위한 중재로 적극적으로 활용될 수 있으리라 생각한다.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.118-123
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• 2001

Most structures of automobile are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic farces for the evaluations of fatigue life and stress concentration exactly. It is rarely obtained the accurate load history of specified positions because of the errors such as modeling, measurement, and etc. In the beginning of design, exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic load determination is developed by the combination of the principal stresses of F.E. analysis and experiment. Inverse problem and least square pseudo inverse matrix are adopted to obtain an inverse matrix of analyzed stresses matrix. Pseudo-Practical dynamic load was calculated for Lab. Test of sub-structure. GUI program(PLODAS) was developed for whole of above procedure. This proposed method could be extended to any geometric shape of structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.104-109
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• 2008

Distribution of welding residual stresses are mainly characterized by degrees and frequencies of thermal loads applied to materials. However, other effects as component size and clamping condition can also affect stress distributions to a certain extent thus careful manipulation of these parameters based on clear understanding of how they affect residual stresses distributions and why can be additional measure to mitigate residual stresses. This paper discusses aforementioned issues for the case of safety and relief nozzle in nuclear power plant through finite element analysis.

• 대한간호학회지
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• 제31권4호
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• pp.610-618
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• 2001

Purpose: This study attempted to grasp the significance of high school boys smoking experiences, and to define its structure, then utilizing the results to create effective nursing intervention in order to protect students from smoking habit. Method: This study is based on a phenomenological approach. A group of eight male high school students who had experience in smoking were selected as the subject of this study. Intimate interview with participatory observation were carried out from them and the resulted data were analyzed by Giorgi's method as below. Result: The male high school students’smoking experiences were found to be a direct result from the environments around them and misty curiosity, masculinity, maintenance of close relations with peers, habitualness, stress relief, and concealment from the family. Conclusion: The result indicates that the male high school students' smoking, especially in an aspect from its starting point, motivational perspective, from the early stage of childhood as possible.

• 대한통합의학회지
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• 제1권1호
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• pp.69-76
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• 2013

Purpose : The purpose of this study is to look into relationship between job stress and self esteem, job satisfation in rehabilition professional physical therapist. Method : The subjects of this study were consist of 200 physical therapists of Busan rehabilition hospital. Data were collected from September 1 to October 4 in 2012 by structurated questionnaires. Results : Physical therapist Job satisfaction and gender classification according to self esteem were statistically significant differences respectively(T=2.02, P=.044), (T=2.17, P=.031). Job satisfaction and age according to the therapist according to the number of job stress were statistically significant differences respectively(F=3.57, P=.030), (F=3.18, P=.044). Job satisfaction, job stress and self-esteem of a physical therapist were statistically significant correlation (P<.01) Conclusion : Effective countermeasure for ways to relieve stress, and the necessity of developing the program at the same time, for the relief of the physical therapist, the physical therapist yourself to have self-esteem.

• 한국식품조리과학회지
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• 제19권4호
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• pp.413-422
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• 2003

The purpose of this study was to investigate the relationship between the dietary attitude and health on the stress status of office - workers in Seoul. This research was conducted on 389 office workers (224 males and 165 female). In relation to stress, it was found that the degree of stress as an office workers was ′slight′ and much for 45.2% and 40.6%, respectively, of the study population. Consequently, most office workers were found to be under stress. The amount of food intake under stress was found to be ′reduced′, unchanged and increased in 38.3, 37.0 and 24.7%, respectively, of those surveyed. The preferred foods when under stress were found to be alcoholic and non-alcoholic beverages, in 57.6% of cases, which was the highest proportion regardless of age, sex, marital status, occupation and educational level. The desired taste when under stress was found to be ′hot′ and sweet in 34.7 and 26.0%, respectively. As to the feeling after food intake, 51.7% responded that food intake was not useful for the relief of stress, which was the highest proportion and many salaried females worried about weight gain. With regard to the relationship between stress, health and nutrition, 69.9% of office workers responded that they thought the relationship of these factors was very high. As for the greatest cause triggering stress, 50.3% responded "due to workplace and job". The best method for relieving stress was to do exercise, with a 30.1 % response, The average score for the degree of stress and tension was 7.2, with 64.0% of office workers having an average level between 6- and 9. The degree of stress was higher for females than males, for unmarried salaried and hot-tempered persons. Those not doing exercise were subject to the highest levels of stress, and those a having sufficient sleep were found to be subject to less stress. Those interested in their health were found to have a good condition and lower levels of stress. In correlation with eating habits, stress, the degree of tension and personality, the F-value was found to be 43.505 (p<0.01), with an explanatory power of 0.294 (29.4%), indicating significant differences. This means that office workers with higher degrees of stress and tension tended to have poorer eating habits. Since bad eating habits have an adverse effect on both the state of physical health and individuals emotional development, for the purpose of correctly managing stress, office workers should make efforts to practice good eating habits.