• Journal of Welding and Joining
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• 제24권2호
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• pp.42-47
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• 2006

While it is known that the weld toe grinding method may give 3.4 times of fatigue strength improvement, this improvement may significantly vary according to weld bead shapes and loading modes. Although tremendous interest have been given in improving fatigue strength improvement for ship structures, quantitative results are yet in need. In this context, a series of fatigue tests is carried out for a type of test specimen that are typically found in ship structures. Weld burr grinding is carried out using a electric grinder in order to remove surface defects and improve the weld bead profile. The test results are compared with the same type of test specimen without applying the fatigue improvement technique in order to obtain a quantitative measure of the fatigue strength improvement. On the other hand, both hot spot stress and structural stress methods are employed to compare the effectiveness of the two methods in evaluating the fatigue strength improvement of welded structures.

• 한국생산제조학회지
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• 제7권5호
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• pp.120-126
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• 1998

Second step shot peening was applied on both smooth specimen and U-notch specimen in order to investigate the stress distribution and the improvement in fatigue strength. Various experiments and measurements such as rotary bending fatigue test and the measurement of compressive residual stress were performed. The results showed that the fatigue strength of second step shot peened specimens increased by 34 percent compared to that of unpeened ones. Compressive residual stress also considerably increased, which resulted in the increase of fatigue strength. finite element analysis showed that shot peening is effective in decreasing the bending stress by external force. The effectiveness of shot peening in reducing the compressive residual stress was anticipated by the superposition of the concentrated stress and the compressive residual stress.

• 원예과학기술지
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• 제35권2호
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• pp.220-231
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• 2017

Grafting using a pumpkin (Cucurbita sp.) rootstock is an effective way to improve cucumber (Cucumis sativus) resistance to a combination of chilling and salinity stresses. We evaluated the tolerance of 15 pumpkin cultivars to chilling, salinity, and combined stresses at the germination and seedling stages. Selected plant characteristics, including germination rate, germination potential, germination index, plant height, stem thickness, fresh weight, and dry weight, were analyzed. We used the unweighted pair group method with arithmetic mean for cluster analyses to determine the stress tolerance levels of the pumpkin cultivars. The 15 cultivars were divided into three clusters: tolerant, moderately tolerant, and susceptible to stress treatments. The stress tolerances of all cultivars were variable in the germination and seedling stages, and most cultivars were not tolerant to individual treatments of chilling or salinity stresses at both stages. These results suggest that identifying suitable cultivars for use as rootstock during cucumber grafting should involve the evaluation of stress tolerance during different growth stages. Additionally, cultivars tolerant to chilling stress may not be tolerant to salinity stress; therefore, the choice of pumpkin rootstock should depend on where the grafted plant will be grown. Cultivars tolerant to a combination of chilling and salinity stresses may be useful as rootstock for cucumber grafting. Our findings may serve as reference material for choosing appropriate pumpkin rootstocks for cucumber grafting.

• 대한한방부인과학회지
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• 제35권4호
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• pp.105-120
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• 2022

Objectives: The purpose of this study is to investigate the perception of Korean Medicine (KM) doctors toward infertility treatment evaluation tools and develop a standard evaluation tool for mental and physical function improvement following Korean medicine treatment. Methods: An online survey (Moaform) was conducted, and responses were analyzed for members of the Society of Korean Medicine Obstetrics and Gynecology and KM doctors who participated in the 2021-2022 traditional Korean medicine treatment infertility support program in Gyeonggi-do. Results: In fertility treatment, the most effective indicators that KM doctors wanted to evaluate other than pregnancy and childbirth were reproductive health indicators, overall health improvement, and stress improvement (33.1%, 21.2%, 18.9%). Furthermore, 45.1% of the respondents had experience using the presented infertility stress evaluation tools. For each evaluation tool, 52.1% and 54.6% of the respondents answered that it 'does not reflect the changing circumstances of the times' and that there were 'too many questions'. As for the developing a standard evaluation tool for infertility treatment in KM, KM doctors expected a simple and clear tool focusing on the pregnancy rate. They also wanted the tool to include a reproductive health index, overall function improvement and stress improvements. Conclusions: The survey confirmed the need to evaluate indicators for reproductive health, mental health, and infertility stress in addition to pregnancy rate to assess the effectiveness of KM infertility treatment. It also confirms the necessity of developing an infertility stress evaluation tool with simplified questions that reflects the changing time.

• 한국주거학회논문집
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• 제20권4호
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• pp.89-102
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• 2009

The purpose of this study is to investigate the influence the need for improvements to dormitory environments and to study the stress from school-life according to residential satisfaction in dormitories and housing. For the purpose of this study, a survey was conducted including a questionnaire consisting of a residential satisfaction scale, a need of dormitory environment improvement scale, and a school-life stress scale. The subjects were 453 special purpose students in Daegu and Gyeongsangbuk-do who all live in a dormitory. Factor analysis, Cronbach' $\alpha$ and MANOVA were employed for data analysis, and Scheffe test was used for post-hoc analysis. First, the lower group the satisfaction of a physical residential environment in a dormitory, the more likely it is that the dormitory environment need improvement. The result of this study suggests that dormitory students are much more sensitive to conditions relating to physical residential satisfaction than to sociopsychological residential satisfaction. Also, the residents believe that change to these physical residential conditions facilitate an improvement to sociopsychological residential satisfaction. Moreover, when the satisfaction of a physical residential environment is lower group, more perceptive stress occurs from academic, health and personal factors while a lower satisfaction for the sociopsychological residential environment results in a more perceptive stress from the environment. The result of this study suggests that dormitory conditions indicate the necessity of improving the environment to adapt well to school-life, thus reducing stress. Also when simply providing a supplementary physical residential environment the sociopsychological residential environment should be considered, as this can cause conflicts between roommates. Second, the lower group the satisfaction for a physical residential environment in housing, the more likely it is that the dormitory environment need improvement. The result of this study suggests that for environments of inadequate housing there is a strong urge towards needing more independence and a better living environment. Third, when group feel there is a more substantial difference in the physical residential environment between dormitories and housing, it is more likely it is that the dormitory environment need to be improved. Also, when they feel there is more substantial difference in the sociopsychological residential environment between dormitories and housing, a more perceptive stress is detected from the environment. The result of this study suggests that dormitory students want to have the same level of conditions as those provided in housing. Also, dormitory students want to need more physical environment improvement than sociopsychological environment improvement.

• Journal of Welding and Joining
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• 제22권2호
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• pp.51-58
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• 2004

Residual stresses, which can be produced during the welding process, play an important role in an industrial field. Welding residual stresses are exerting negative effect on the fatigue behavior and integrity of structure. In this study, as a result of the thermal elasto-plastic finite element analysis for the welds of a nuclear component, the residual stress distributions are estimated for as-welded condition. Also, finite element techniques are developed to simulate the relaxation of the residual stresses according to the various mechanical stress relieving(MSR) loads such as hydrostatic pressure loading, tensile pipe-end loading, and mechanical stress improvement process(MSIP) loading. Finally, the results of residual stress redistributions for various loading conditions are compared and reviewed qualitatively and quantitatively to find an optimum loading condition.

• 한국자동차공학회논문집
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• 제12권1호
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• pp.196-202
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• 2004

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue life and strength. By using the methods mentioned above, the following conclusions have been drawn. 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ΔKth, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.121-124
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• 1998

It is well known that during the oxygen cutting residual thermal stresses are produced in weldment. Surface compressive residual stress is one of reasons for improvement on fatigue durability. To reduce the residual stress and improve the fatigue strength applied the impact loading in oxygen cutting frame. After applying the impact loading, redistribution of residual stress was measured by cutting method and tested fatigue tests.

• 한국산업보건학회지
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• 제26권4호
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• pp.426-435
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• 2016

Objectives: The major objective of this study was to analyze stress response after a change to consecutive day shifts from day and night shifts in a motor assembly factory. Methods: Using a survey conducted by a labor union, we collected data on stress response index(SRI), lifestyle factors, work-family conflict and job stress before and after a shift system change. We analyzed the transition on the SRI among 222 workers. The cut-off point for the SRI was a T-score over 60. Results: The high risk stress response group was 20.3% of the population before the shift system change. After the shift system change it decreased to 11.3%. After the shift system change, social support improved, leisure time became more sufficient, work-family conflict declined, and sleep quality in the night shift week improved. In multivariable linear regression, among workers under 40 years old sleep quality on night shift, leisure time sufficiency, social support and work-family conflict contributed to the improvement of stress response. Among workers over 40, work-family conflict contributed to the improvement of stress response. Conclusions: The change to consecutive day shifts improved stress response and mediated with improved nighttime sleep, decreased work-family conflict, increased leisure time and improved work-family conflict.

• 동의생리병리학회지
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• 제25권5호
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• pp.843-848
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• 2011

In Korea, China, and Japan, Paeonia lactiflora Pall (PL) has been used in the treatment of rheumatoid arthritis, hepatitis, and fever for more than 1200 years. It has been reported that PL has protective effects against $H_2O_2$-induced oxidative stress and LPS-induced liver inflammation. However cellular and molecular mechanism of PL protection against oxidative stress has not fully been elucidated. Here, we describe that the water-soluble extract of PL decreased $H_2O_2$-induced hepatotoxicity. This hepatoprotective effect of PL is reason to decrease the level of intracellular reactive oxygen species (ROS) and increase expression of heme oxygenase 1 (HO-1) and heat shock protein 72 (HSP72) which proteins are involved in protecting the cells from stress like as oxidative stress. We also elucidated that hepatoprotective effect of PL was abolished by knock down of HO-1 and HSP72 by siRNA. These results suggest that the increasing of HO-1 and HSP72 protein by PL treatment might be participated in hepatoprotective effect against oxidative stress such as $H_2O_2$.