• Laser Solutions
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• v.4 no.2
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• pp.13-19
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• 2001

When a high-power laser beam is irradiated on the surface of material, it is well known that a cavity, called a keyhole induced by the pressure action of the vapor plume, is generated in the molten material. This paper describes the interaction between a pulsed CO$_2$ laser beam and water. The laser-beam is used to generate and maintain a conical depression in the water surface similar to the keyhole created during laser penetration welding. Experimental results show that the depth of laser-beam penetration is limited by hydrodynamic instability. The instability of the surface cavity can be understood by the capillary instability of a hollow jet. Theoretical computation of the steady keyhole shape has been performed. modifying the model suggested by Andrews et al. (1976). The model predicts the qualitative behavior of the keyhole but significantly underestimates the average diameter.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.111-115
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• 2008

This paper describes the optimization of injection molding conditions to minimize sink marks. Sink marks, which refer to a small depression on the surface opposite a thick wall thickness, are often encounted in injection molded plastic parts. Part geometry, material properties and processing conditions during injection molding can affect the sink mark depth. We designed the runner system which is possible balanced filling to cavities using CAE program $Moldflow^{TM}$ and then obtained optimal processing conditions by Taguchi's Robust Design technique. By actual injection molding using optimized mold and molding conditions, it confirmed that sink mark depth decreased zero compared to 1mm level in the conventional mold and process.

• Tribology and Lubricants
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• v.20 no.3
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• pp.125-131
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• 2004

Nano-wear behavior of amorphous carbon films was studied by Atomic Force Microscopy. The a-C films are deposited on Si(100) substrate by DC magnetron sputtering method. The influences of different surface roughness on the nano-wear are investigated. Nano-wear tests were carried out using a very sharp diamond coated tip. Its spring constant was 1.6 N/m and radius of curvature was 110 nm. Normal force used in the wear tests ranged 0 to 400 nN. It was found that surface depression occurred during scratching because of plastic deformation and abrasive wear (cutting St ploughing). Wear depth increased linearly with normal force. Changing the surface roughness variables according to the bias pulse control, the less surface roughness decreased the wear depth. The thickness did not affect the wear resistance.

• Journal of Digital Convergence
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• v.19 no.12
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• pp.541-548
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• 2021

This study analyzed the path through which elderly discrimination experience, sense of loss, and depression lead to suicidal ideation by verifying the influence of elderly discrimination experience on suicidal ideation and the mediating effect sense of loss and depression. The subjects of the study were a 1:1 in-depth interview survey of 400 elderly people aged 65 or older using stratified sampling methods by region and type of 31 city, county, and district the elderly welfare welfare centers(10 locations) in Gyeonggi-do. As a result, a total of 360 samples were finally analyzed. It was verified through frequency analysis, descriptive statistics analysis, correlation analysis, structural equation and bootstrapping analysis methods using SPSS 25.0 and AMOS 23.0. As a result of the study, first, it was found that the more the elderly experienced discrimination, the higher the suicidal ideation. Second, the effect of sense of loss was partially mediated on the effect of discrimination experience on suicidal ideation in the elderly. Third, the feeling of depression was found to play a partial mediating role between the experience of discrimination among the elderly and suicidal ideation. Based on the results of this study, policy and practical suggestions were made to alleviate the suicidal ideation of experiences of discrimination against the elderly and sense of loss and depression to prevent suicide among the elderly.

• Korean Journal of Adult Nursing
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• v.27 no.2
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• pp.156-169
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• 2015

Purpose: This study identified the reasons why tuberculosis (TB) patients withhold treatment in a bid to develop a assessment scale to select patients who needs nursing intervention in the early stage and decrease the risk of discontinuation of treatment. Sample: There were two samples. A sample of 191 patients with TB and having primary treatment and a second sample of N who were under re-treatment Methods: The study design included qualitative and quantitative methods. Qualitative data were collected from in-depth interviews of TB patients under re-treatment. The quantitative data were collected from 191 patients with TB under primary treatment. Results: Exploratory factor analysis revealed 11 factors explaining 69.6% of total variance. These factors were categorized into four subgroups. A depression scale was used to establish concurrent validity. The depression scale had a positive relationship (r=54) with the discontinuing of primary treatment. The internal consistency reliability for the four subgroups was over .84. The confidence coefficient was Cronbach's ${\alpha}$ .95. The final scale was a self-reported four Likert scale including 50 items. Conclusion: Reliability and validity was established for the scale and the scale can be used to examine the risk of treatment discontinuation for TB. The scale is an important resource for nursing interventions in identifying and treating high risk clients.

• Journal of Korean Public Health Nursing
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• v.14 no.2
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• pp.203-215
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• 2000

The purpose of this study is to identify the effects of the supportive program for arthritis patients. who are attending a rheumatoid arthritis clinic. To achieve this purpose. this study adopted a quasi-experimental. pre- and post-test research design. comparing experimental group with control one. Supportive program was composed of in-depth. 3 times of direct interview and 2 times of advice using telephone for 8 weeks. The object of these interviews and phone was focused on the improvement of patients' preception for health. During this period. the level of pain, hemato-immunologic indices(ESR, CRP). self-efficacy, depression. and perception for health were measured in both grooups. Data were analysed by $x^2-test$, t-test. repeated measures ANOVA and Pearson's correlations. The results were as follows : 1. There were no significant differences in physiological data. 2. The feeling of self-efficacy was significantly increased in experimental group(P=.012), 3. There was no significant differences in depression. 4. The perception for health status was significantly increased in experimental group(P=.002). Thus, the supportive program. which is focused on the close interpersonal communication. proved to be effective. This result justifies the following suggestion that the role of the nursing professionals in out-patient clinic should be extended for more qualified care for the patients.

• Journal of Korean Academy of Nursing
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• v.51 no.3
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• pp.347-362
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• 2021

Purpose: This study developed a cognitive behavioral therapy program aimed at altering the physical condition, emotions, and behaviors of fibromyalgia patients, and confirmed the program's clinical applicability. The program was developed by analyzing previous studies conducting in-depth interviews with fibromyalgia patients, drawing on cognitive behavior theory to establish the program contents, recruiting experts to test its validity, and conducting a preliminary survey. Methods: To confirm the program's effect, this study used a randomized controlled trial design. The participants were outpatients diagnosed with fibromyalgia in Dong-A University Hospital, Busan. The 30 patients in the experimental group took part in the program, which comprised 8 sessions (90 to 120 minutes) based on cognitive behavior theory, delivered over 8 weeks. Hypothesis testing was carried out using the repeated measures ANOVA. Results: The analysis revealed significant differences between the experimental and control groups in positive automatic thoughts, pain, fatigue, depression, and interpersonal relationships. However, there was no significant difference between the groups in terms of sleep disorders and negative automatic thoughts. Conclusion: This program is a positive effect on physical condition, emotions, and behaviors. It is thus expected to be used to help fibromyalgia patients improve their disease conditions.

• The Korean Journal of Community Living Science
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• v.23 no.4
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• pp.419-439
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• 2012

Family dissolution and economic difficulties of the grandchild's parents are the most prevailing reason for an increase of grandparent-headed families in rural Korea. However, there is a lack of empirical research looking at the experiences of custodial grandmothers, social support, and their psychological well-being. In this regard, this study examined the effect of social support (formal & informal) on the psychological well-being of custodial grandmothers in rural Korea. For this purpose, quantitative and qualitative research methods were conducted. Quantitative data were gathered, using structured questionnaire, from 311 grandmothers who were raising their grandchildren in rural Korea as primary care-givers. Statistical methods used for data analysis were descriptive statistics and hierarchical regression analysis with SPSS WIN 19.0 programs. Qualitative data were collected by in-depth interviews to 10 custodial grandmothers in rural area. The results of this study are as follows. First, almost half of the parents of the grandchild didn't visit and didn't call anymore. Some relatives -aunt, uncle, etc.- support the grandparent-headed family economically and emotionally. 3/4 of the grandparent-headed families were supported by the government and community. This was not small numbers, but the amount of economic support was low. Second, grandmothers in the study showed quite a high level of depression while their happiness level was relatively low. There were differences in the factors influencing the level of happiness/depression of these rural grandmothers. Overall, the study's results showed the importance of formal & informal support for psychological well-being of the custodial grandmothers in rural Korea. Policy and theoretical implications are discussed.

• Journal of Oriental Neuropsychiatry
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• v.34 no.3
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• pp.151-161
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• 2023

Objectives: To examine effect of Korean medical treatment on patients with insomnia and correlations among changes in psychological scales before and after treatment. Methods: Medical records of 38 patients diagnosed with insomnia based on DSM-V who received Korean medical treatment (herbal-medication, acupuncture, Korean psychotherapy) for at least 8 weeks were retrospectively reviewed. Psychological scales including Insomnia Severity Scale (ISI), Beck Depression Inventory-II (BDI-II), State-Trait Anxiety Inventory (STAI), Beck Anxiety Inventory (BAI), and State-Trait Anger Expression Inventory (STAXI) were measured every four weeks and analyzed. Results: After eight weeks of treatment, ISI, BDI-II, BAI, STAI-X-1/2, and STAXI-S/T showed statistically significant decreases. Psychological scale pairs that showed a statistically significant correlation were ISI and BDI-IIㆍSTAI-X-1ㆍSTAI-X-2ㆍTA, BDI-II and BAIㆍSTAI-X-1ㆍSTAI-X-2ㆍAX-I, BAI and STAI-X-1ㆍSTAI-X-2ㆍSAㆍTA, STAI-X-1 and STAI-X-2, SA and TA, and TA and AX-I. In women, the improvement of AX-C was high. The improvement in AX-I score was significant when the disease duration was more than one year. A lower pretreatment BAI value predicted a greater decrease in ISI score after treatment. Conclusions: Korean medical treatment including herbal medicine, acupuncture, and Korean psychotherapy was effective in improving insomnia symptoms and accompanying symptoms such as depression, anxiety, and anger. In the future, more in-depth follow-up research is needed on the mechanisms by which various psychological problems (depression, anxiety, anger, etc) cause and worsen insomnia and the psychological symptoms secondary to insomnia.

• 한국노년학
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• v.29 no.2
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• pp.529-546
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• 2009

Depression in old age not only is prevalent but also causes a considerable amount of burden in physical, psychosocial, and economic terms. Intervention, however, is often delayed due to the understanding that considers depressive symptoms as a normal process of aging or signs of physical illnesses. Since the recognition of symptoms often initiate one's help seeking process, a correct identification of symptoms can contribute to early detection and intervention to depression in oneself as well as in others. This study interviewed 104 older adults living in an urban area, and explored their ability to correctly identify depressive symptoms and factors related to identification. The study results show that respondents who were able to correctly identify symptoms of depression were only 14%, and the rest defined the symptoms as social, economic, and other psychological issues. Of the factors in the logistic regression model, age being 75 and over and mass media as source of mental health information affected negatively their ability to correctly identify symptoms; mental health education programs affected positively their ability. Based on these results, it is suggested that such strategies as employing a face-to-face provision of concrete information and counseling can be more effective than delivering information via large-scale lectures. Additionally, a future research deems necessary to conduct an in-depth examination of mental health/illness-related contents on mass media.