• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.16-16
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• 1998

우주발사체용 로켓트 구조재로 사용되는 알루미늄합금 단조재는 강도확보를 위하여 고온으로 가열후 급냉과정에서 상당한 크기의 잔류응력이 발생되고 이로 인해 기계가공시 변형이 유발되어 조립성이 나빠진다. 잔류응력은 그 크기가 재료의 항복강도를 초과할 때 제거되므로 응력제거(stress relief)를 위해서는 외부하중이 가해져야 한다. 응력제거 처리는 소성변형, 열처리 및 초음파 등의 방법으로 수행되며 소성변형에 의한 제거효과가 가장 크다 형상이 복잡한 형 단조재의 경우 열간단조금형과 동일한 금형을 이용하는 TX52 등의 방법을 적용한다고 알려져 있으나 TX54에 대한 금형설계 및 소성변형률 적용 데이터는 공정 know-how로 분류되어 있다. 잔류응력제거 처리의 해석적 연구로는 판재와 링롤재에 대해서는 인장 및 압축 소성변형에 적용에 대한 결과가 발표된 바 있으나 형 단조재의 경우에는 전무하다

• Journal of the Korean Ceramic Society
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• v.30 no.2
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• pp.164-168
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• 1993

Grinding of 3mol% Y-TZP enhanced the texturing of t-ZrO2, which is represented by the increased I(002)t/I(200)t peak intensity ratio, and an asymetric broadening of (111)t peak. The degree of texturing and asymetric broadening depended on a seversity of grinding. The asymetric (111)t peak broadening was resulted by the formation of r-ZrO2. When aged at 25$0^{\circ}C$ for 120h, r-ZrO2 transformed to t-ZrO2 due to the relief of stressed surface area and the amount of tlongrightarrowm transformation inversely varied with the I(002)t/I(200)t. The inverse dependence was interpreted by that the degree of texturing determines the magnitude of residual surface stress and the lattice relaxation of t-ZrO2, which causes the low temperature degradation, is retarded as the residual stress becomes greater.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.695-696
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• 2008

This paper deals with the reduction of DC component of cogging toruqe by using the heat treatment of the stator core. The stator core is made of electrical steel sheared by the punching die. From the punching process, large mechanical stress at the edge of stator tooth induces significant plastic and elastic deformation and influences magnetic properties. Then, these phenomenon in the sheared region has influence on the magnetic unbalance in the air-gap of motor. This paper investigated the effect of the punching process on the magnetization process and the mechanical deformation and proposed the stress relief annealing method for the reduction of friction torque among one of motor characteristics.

• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.43-54
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• 2019

Due to various numerical problems, crack analysis of reinforced concrete members using the finite element method is confronting with substantial difficulties, rendering the prediction of crack patterns and crack widths a formidable task. The root cause is that the conventional analysis methods are not capable of tracking the crack sequence and accounting for the stress relief and re-distribution during cracking. To address this deficiency, the crack queuing algorithm has been proposed. Basically, at each load increment, iterations are carried out and within each iteration step, only the most critical concrete element is allowed to crack and the stress re-distribution is captured in subsequent iteration by re-formulating the cracked concrete element and re-analysing the whole concrete structure. To demonstrate the effectiveness of the crack queuing algorithm, crack analysis of concrete members tested in the literature is performed with and without the crack queuing algorithm incorporated.

• Journal of Korean Academy of Nursing
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• v.33 no.8
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• pp.1171-1177
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• 2003

Purpose. Despite many smoking cessation programs, many patients with CAD continue to smoke or re-smoke. The processes of change and self-change for smoking cessation is emphasized. The purpose of present study was to investigate decisional balances and processes of change according to stages of change for smoking cessation in the patients with CAD. Methods. This descriptive study was performed using the self-reported questionnaires from 157 male patients with CAD who have smoking experiences. The questionnaires consisted of decisional balances toward smoking (pros/cons) and processes of change including 7 factors. Results. 45.2% of the subjects had myocardial infarction and 54.8% for angina pectoris. Major stages of change were maintenance, contemplation, and precontemplation in 62%, 14%, and 18% respectively. The mean score of pros smoking was 31.07 and cons smoking was 32.52. The mean scores of processes of change were high in all 7 factors, especially in self determination. The pros smoking in precontemplation stage was significantly higher than those in other stages. Between contemplation and precontemplation stages, processes of change showed significant differences in stimulus control, self determination, information management, and dramatic relief. Conclusion. This study suggests that decisional balances and processes of change are stage-specific. As this study, smoking cessation program in the patients with CAD must put priority on the patients group in pre-contemplation and contemplation stages, and stress self determination and dramatic relief.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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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.

• Fire Science and Engineering
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• v.33 no.5
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• pp.130-139
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• 2019

This study identified the level of task stress experienced by fire protection system management workers and analyzed the effects of task stress on job satisfaction and proposed future response. First, task stress according to background cause showed differences in relation to age, position, monthly salary, total career, license, and task, but there was no difference in relation to academic background. Second, of the sub-parameters of stress, physical environment, task demand, organizational system, lack of reward, and workplace culture have negative effects on job satisfaction as stress increases, while interpersonal relation conflict and job insecurity do not have any effect. In the future, it will be necessary to investigate the empirical causes of work overload and to study organization-level stress relief measures.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.145-151
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• 2022

In the study, the author aims to investigate the social media platform that helps promotion of stress relieve and social abilities that exist in lifestyle of persons living in the modern times and perform literature studies of characteristics of stress in each life cycle and social media thereof. In results, it is concluded that persons living in the modern times are under various stress during adolescence, middle age and elderly periods of the entire life cycle and especially, in Korea, stress index is increasing rapidly. To resolve stress, as an alternative, internet based social medial platform can be used to achieve various information supply and access. It is suggested that the development and accessibility of platforms for each inclination should be made easy in line with each inclination and desire for complex and diverse personal inclinations and individualistic activities, and related research should be continued.

• Journal of Oral Medicine and Pain
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• v.22 no.2
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• pp.359-371
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• 1997

Stress is recognized as a major predisposing and/ or precipitating factor in long-lastig intractable chronic pain, such as temporomandibular disorders, headache, and other psychophysiological disorders. So it is necessary to detect physical and psychological changes induced by stress as soon as possible for positive treatment outcome. This study was performed to investigate the occurrence rate of stress symptoms according to anatomic region, type of symptom, and other personal and social factors. 859 subjects from general population answered the stress symptom questionnaire devised by the author and composed of 50 items. Data from the questionnaire were analyzed statistically with SPSS program and the results obtained were as follows : 1. Oral symptom which showed the highest frequency rate of 38.8% was vesicular lesion of the lip and cheek. The other symptoms with more 20% occurrence rate were ulcerative leion of lip and cheek, toothache, paresthesia of teeth, eruption of tongue, tongue coating and taste change in descending order. 2. In extraoral symptoms, ？데 disturbance was the item which showed the highest frequency rate of 62.0%, and the items for stiffness of suboccipital region and neck, headache, facial swelling, furuncle of face were answered more than 45% of the subjects whereas only 14.0% of the subjucts complained jaw pain under stress. 3. The better one who thought his or her health status was, the fewer items were answered and the difference of symptom frequency by dwelling place and by having hobby were shown in extraoral symptoms only. 4. For relief of stress symptoms, 79.2% of the subjects replied only to take a rest whereas not more than 13, 5% of the subjects visited dental clinic. Correlationship between symptom sites were very high.

• Child Health Nursing Research
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• v.8 no.2
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• pp.141-151
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• 2002

The purpose of this study was to find out the correlations between mother-adolescent communication and quality of life in the adolescents. The study subjects consisted of 171 adolescents who were going to middle school and high school. The data included general characteristics, health related characteristics, stress, mother-adolescent communication and quality of life. The data were analyzed by frequency, mean, percentage, t-test, ANOVA and Pearson's correlation using the SPSS statistical program. The result were as follows: 1. The mean score for the stress of adolescent was 2.48(maximum score: 5) and there were significant difference according to demographic variables that is sex, grade, father's being and health related variables that is health status, frequently ill, illness severity and illness of family. 2. The mean score for the mother-adolescent communication was 3.27(maximum score : 5) and there were significant difference according to demographic variables that is father's and mother's being. There were no significant difference according to any health related variables. 3. The mean score for the quality of life of adolescent was 3.97(maximum score : 7) and there were no significant difference according to demographic and health related variables. 4. There was a negative correlation between the stress and the quality of life. There was a positive correlation between the quality of life and the mother-adolescent communication. There was a no correlation between the mother-adolescent communication and the quality of life. Consequently, the implication for nursing of this study is that there is a need to develop relief strategy of stress for the female adolescents. And there is a need to develop a promoting program of quality of life for the adolescents considering the stress and the mother-adolescent communication.