• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.27-35
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• 2001

For the purpose of healing the degradation part, $CO_2$ laser beam was irradiated with different irradiation condition (porer, diameter, velocity and beam type) to find out optimum irradiation condition. The test series of hardness, residual stress measurement, and fatigue were carried out after the irradiation. Experimental results show that micro-hardness values on the surface of the irradiated specimens m approximately 2.5 times higher than those of un-irradiated ones. Fatigue tests show that the fatigue life was improved by the compressive residual stress after laser beam irradiation. However, some specimens with different conditions show the shorter fatigue life. It means that laser beam irradiation with optimum irradiation condition and optimum absorb energy, Q can improve the fatigue strength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.266-269
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• 1997

Hot carrier effects as a function of bias stress time and bias stress conditions were syste-matica1ly investigated in p-channel po1y-Si TFT's fabricated on the quartz substrate. The device degradation was observed for the negative bias stress. After positive bias stressing, Improvement of electrical characteristic except for subthreshold slope was observed. It was found that these results were related to the hot carrier injection into the gate oxide and interface states at the poly-Si/SiO$_2$interface rather than defects states generation under bias stress.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.2
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• pp.202-208
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• 2005

Stress and fatigue life analyses are performed to enhance a fatigue life of a heating drum of the roller press for medium density fiberboard. The finite element method employing the submodel is used to analyze stress concentration in the journal of the heating drum. The fatigue life is evaluated by the stress-life theory. Two modified designs of the journal are suggested and evaluated to reduce the maximum stress and to increase the fatigue life Their structural reliabilities are verified in terms of the yield strength and the design life.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.245-254
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• 2022

This study is a study to empirically verify the mediating effect on college life adaptation and career preparation behavior of college students. The purpose of this study is to empirically analyze the multi-mediated effects of major satisfaction, job stress, and self-directed learning. For this study, 216 university students were enrolled. For the collected data, SPSS Process macro was used. The result is as follows. First, there were multiple parallel mediating effects and multiple serial mediating effects on major satisfaction, job stress, and self-directed learning between college life adaptability and career preparation behavior. Second, the path of simple mediation and double mediation effect was found between college life adaptation and career preparation behavior. Based on the research, the necessity of revitalizing the program for revitalization of teaching activities and industry-academic cooperation activities in the major field and improvement of career preparation behavior and university life adaptation ability and follow-up research were suggested.

• Journal of Environmental Science International
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• v.33 no.4
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• pp.249-256
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• 2024

This study aimed to verify the healing effect through brain and pulse wave analyses before and after a forest walk to the university students. Bio-signals of brain and pulse waves were measured using Omnifit Mindcare. After analyzing four brain wave items such as concentration and four pulse wave items such as heart health, it is identified that the stress level of university students was higher than that of the general public, and the brain stress level was approached to the normal range for 19 people with clear improvement. For pulse waves, a statistically significant decrease in sympathetic nerve activity (%) was confirmed. Although the slight fluctuations within the normal range were caused by short term and individual differences, it showed that the forest walking is partially effect on the relieving stress.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.706-713
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• 2004

This paper introduced an alternative method called USCP (Unpenetrated Sand Compaction Pile). In USCP, the toe of the sand pile does not reach to the lower supporting layer. Hence it is possible to reduce the amount of sand required. However, the degree of improvement could not be the same as SCP. Effective soil improvement, nevertheless, might be possible by combining both methods. In this paper, an improved method that cross over both SCP and USCP was discussed. And in order to verify applicability to a clay layer, consolidation behaviors with different conditions were analyzed and compared using FEM(Finite Element Method) based on the elasto-viscosity theory. From the results, it is concluded for the characteristic of settlement of USCP that the lower degree of replacement and the smaller ratio of penetration($H_d/H$), the larger is the settlement of the lower part of the clay layer comparing to the layer with no improvement. It is also concluded that the ratios of allotment of stress (m) calculated from the final settlements with 30% of degree of replacement are $1.8{\sim}3.3$ for $H_d/H=lOO%,\;1.8{\sim}4.0\;for\;H_d/H=75%,\;and\;1.8{\sim}3.8\;for\;H_d/H=50%$. Besides, the ratio of allotment of stress decreased as the degree of replacement decreased.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.1
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• pp.49-56
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• 2022

Objective: Oxidative stress and sperm DNA fragmentation (SDF) have been linked to idiopathic male infertility (IMI). Various antioxidants have been tried to improve semen parameters and fertility potential in IMI patients, but with inconsistent results. The study aimed to compare the effects of coenzyme Q10 (CoQ10) and Centrum multivitamins on semen parameters, seminal antioxidant capacity, and SDF in infertile men with idiopathic oligoasthenospermia (OA). Methods: This prospective controlled clinical study involved 130 patients with idiopathic OA and 58 fertile controls. The patients were divided randomly into two groups: the first group received CoQ10 (200 mg/day orally) and the second group received Centrum multivitamins (1 tablet/day) for 3 months. Semen parameters, CoQ10 levels, reactive oxygen species (ROS), total antioxidant capacity (TAC), catalase, SDF, and serum hormone levels (follicle-stimulating hormone, luteinizing hormone, testosterone, and prolactin) were compared at baseline and after 3 months. Results: Both CoQ10 and Centrum improved sperm concentration and motility, but the improvement was greater with Centrum therapy (p<0.05). Similarly, both therapies improved antioxidant capacity, but TAC and catalase improvement was greater (p<0.01 and p<0.001 respectively) with CoQ10, whereas ROS (p<0.01) and SDF (p<0.001) improvements were greater with Centrum administration. Centrum therapy was associated with reduced serum testosterone (p<0.05). Conclusion: In conclusion, both CoQ10 and Centrum were effective in improving semen parameters, antioxidant capacity, and SDF, but the improvement was greater with Centrum than with CoQ10. Therefore, Centrum-as a source of combined antioxidants-may provide more effective results than individual antioxidants such as CoQ10 in the treatment of infertile men with idiopathic OA.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.315-322
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• 2001

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance for electric cables. In this paper, stress and strain of flexible pipes with various depth are calculated using traditional formula and FEM analysis. The results show that theoretical values are more conservative in strain whereas FEM analysis gives larger stress. Considering the strain criteria - 3.5 %, maximum, flexible pipes can be buried at the range of 50cm to 5m in depth without additional soil improvement.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.326-329
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• 2009

We investigated the degradation of $In_2O_3-Ga_2O_3$-ZnO (IGZO) thin-film transistors (TFTs), which is promising device for driving circuits of nextgeneration displays. We performed the electronic stress test by applying gate and drain voltage. We discussed the degradation mechanism by thermal analysis and device simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.659-669
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• 2016

The purpose of this study was to examine, among quality improvement (QI) department employees, the effects of perception of the healthcare accreditation on job stress and to identify factors affecting turnover intention. Research data was collected between 1 June and 15 June 2016. The sample included QI department employees who had participated in a healthcare accreditation survey. The collected data were analyzed to obtain frequency, percentage, mean and standard deviation results, which were assessed by using Student's t-test, ANOVA, and multiple regression analysis. The scores for QI employees' perceptions of the healthcare accreditation, job stress, and turnover intention were 3.35, 3.66, and 3.32 of the perception by general characteristics. There were significant differences between scores according to gender, age, QI department section, position, and job satisfaction. In addition, job stress and turnover intention scores showed significant differences according to position, age, QI department section, and job satisfaction. A positive correlation was observed between healthcare perception and job stress, while turnover intention was negatively correlated with healthcare perception. The results indicate that the perception of healthcare accreditation positively affects job stress; in contrast, it decreases the number of people intending to change departments. Among the sample of lower level workers, the younger age workers who were employed for more than 10 years expressed lower satisfaction with their job, which indicates that they are affected by their notion of healthcare accreditation more than by other factors. Thus, in order to lessen work stress and employees' thoughts of leaving the department, the QI department should be encouraged to lessen job stress and provide various supports to the employees.