• Journal of Biomedical Engineering Research
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• v.15 no.2
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• pp.183-188
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• 1994

In clinical orthopaedics, bone resoption in the cortex is often seen post operatively on X-rays or bone densitometry after total hip replacement (THR) in the form of cortical osteoporosis or atropy. Stress shielding of bone occurs, when a load, normally carried by the bone alone, is shared with an implant as a result, the bone stresses are abnormal and with remodelling analysis this may cause extensive proximal bone resoption, possibly weakening the bone bed to the point of failure. The author made finite element models of the cemented and non-cemented type implanted femoral stem with bone resorption of the proximal medial femur and studied the feed back effect of the various degree of bone resoption to THR system by parametric analysis on the stress of the femoral stem and interface. The results of the present finite element analysis implied that the extent of proximal bone resorption has the effect of more increasing stress on the distal stem tip, cement mantle and interface in both type of femoral stem and this high distal stress possibly can cause the mechanical failure of loosening or failure after THR.

• The Journal of Korean Obstetrics and Gynecology
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• v.18 no.3
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• pp.51-66
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• 2005

Purpose : Investigate the effects of Haeganjeon water extract (HGJ) on immobilization-stress or cold-stress in C57BL/6J mice. Methods : Male C57BL/6J 30 mice of weighting 18${\pm}$2g, were divided into sixs groups including the immobilization-stress group(5heads), after immobilization-stress HGJ oral administration(500mg/kg) groups(5heads), cold-stress group(5heads) and after cold-stress HGJ oral administration(500mg/kg) groups(5heads). then we observed changes in the serum histamine and corticosterone level and changes immune system. Results : HGJ decreased the serum level of histamine and corticosterone increased by immobilization-stress or cold-stress. HGJ inhibited the release of histamine from mast cells. In addition, HGJ enhanced the cell viability of thymocytes decreased by immobilization-stress or cold-stress and decreased DNA fragmentation of thymocytes increased by immobilization- stress or cold-stress. Also, HGJ increased the cell viability of splenocytes decreased by cold-stress and decreased DNA fragmentation of splenocytes increased by cold-stress. HGJ decreased the population of thymic CD4+ cells increased by immobolization-stress. HGJ increased the population of B220+ cells decreased by immobilization-stress and decreased the population of Thy1+ cells increased by immobilization-stress. Also, HGJ decreased the population of splenic CD4+ cells increased by immobolization-stress. HGJ enhanced the production of ${\gamma}-interferon$ decreased by immobilization-stress or cold-stress and increased the production of interleukin-4 decreased by immobilization-stress. Furthermore, HGJ enhanced the phagocytic activity decreased by immobilization-stress or cold-stress and enhanced the level of nitric oxide decreased by immobilization-stress or cold-stress. Conclusion : HGJ may be useful for the prevention and treatment of stress via suppression of serum histamine and corticosterone level and enhancement of immune response.

• Journal of Korean society of Dental Hygiene
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• v.14 no.3
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• pp.381-390
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• 2014

Objectives : The purpose of the study is to investigate the relationship between job-stress and temporomandibular joint(TMJ) disorder in dental hygienists. This study will provide the basic data to improve the working condition and the quality of life. Methods : The subjects were 229 dental hygienists at general hospitals in Seoul, Korea. A self-reported questionnaire was filled out from May 20 to June 20, 2013. The questionnaire consisted of 4 questions of demographic features, 11 questions for TMJ symptoms and 5 questions for job stress. The data were analyzed by frequency analysis, chi-square test, Mann-Whitney U test and multiple job-stress logistic regression analysis using SPSS version 21.0. Results : During the last six months, 53.3%(122 persons) of the dental hygienists had TMJ disorder symptoms including joint noise(40.6%, 93 persons), TMJ pain(31.4%, 71 persons) and limitation of TMJ(21.8%, 50 persons). Job-stress is divided into two ranges including high stress group(4.3-5.0 points) and low stress group(0.0-3.6 points) in TMJ pain and joint noise(p<0.05). TMJ pain was closely related to low back pain, pelvis pain and tension headache arising from the uncomfortable working posture. Conclusions : It is necessary to prevent the job stress in the dental hygienists by the improvement of working condition, emotional stability, and frequent postural change.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.79-86
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• 1995

The structural materials for cryogenic technology have been recently developed to support the many modern large-scale application from superconducting magnets for nuclear fusion reactor, magnetic levitation railway to LNG tankers. However it is pointed out that quenching phenomenon is one of the serious problems for the integrity of these applications, which is mainly attributed to the rapid temperature rising in the material due to some extrinsic factors of structures. From the viewpoint of fracture mechanics, it is therefore very important to clarify the mechanism of temperature rising of structural material due to cyclic loading at cryogenic temperature. From this purpose, fatigue test was carried out for high manganese steel at liquid helium temperature(4.2K) using triangular stress waveform to identify both the mechanism of temperature rising near crack tip and the effect of loading stress waveform on temperature rising near crack tip and the effect of loading stress waveforms on temperature rising. As the results, two types of temperature rising, that is, regular and burst types were observed. And a periodical temperature rising corresponding to the stress waveforms was also found. The peaks of the temperature rising were recorded near both the maximum and the minimum values of the applied stress. The sudden temperature rises, which indicated the higher values than those of periodical temperature rises under the repetition of stress, were observed at the final region of crack growth. It was shown that the peak values of the temperature rising increased with stress intensity factor range.

• KIEAE Journal
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• v.16 no.3
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• pp.121-128
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• 2016

Purpose: The vacuum glazing should constantly retain the gap in vacuum state to maintain high thermal performance. To do so, pillars are used to prevent the glazing from clinging to each other by the atmospheric pressure and therefore surface of the vacuum glazing is consistently affected by residual stress. The vacuum glazing could be applied to curtain wall systems at spandrel area to fulfill a rigorous domestic standard on U-value of the external wall. However, this can lead to high glazing temperature increase by heat concentration at a back panel and finally thermal stress breakage. This study experimentally determined weakness of the vacuum glazing systems on the thermal stress breakage and investigated effect of the residual stress. Method: The experiment first built two scale-down mock-up facilities that replicate the spandrel area in curtain wall, and then installed single low-e glass and vacuum glazing respectively. The two mock-up facilities were exposed to outside to induce the thermal stress breakage. Result: The experiment showed that the temperature occurred the thermal stress breakage was $114.4^{\circ}C$ for the single low-e glass and $118.9^{\circ}C$ for the vacuum glazing respectively. The result also showed the vacuum glazing reached the critical point earlier than the single low-e glass, which means that the vacuum glazing has high potential to occur the thermal shock breakage. In addition, the small temperature difference between two glazing indicates that the residual stress scarcely affects breakage of the vacuum glazing.

• Korean Journal of Occupational Health Nursing
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• v.23 no.1
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• pp.20-27
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• 2014

Purpose: This study was conducted to identify the association between emotional labor and job stress in bus drivers, as well as to propose management strategies for job stress. Methods: The study was conducted in February 2013 and involved 182 bus drivers working in the Gyeonggi area. Results: emotional labor was $9.5{\pm}2.34$ on average, and job stress was higher than the median of the same indicator among Korea's workers in the areas of physical environment, job autonomy, and relationship conflicts. Factors that affected job stress was lower if the subjects' Higher values for emotional labor indicated a higher level of job stress. Conclusion: To reduce among drivers, the following measures are necessary: increase the comfort of the driver's seat within the vehicle, provide adequate rest between bus headways, provide comfortable in-house rest facilities, and establish physical training spaces to reduce musculoskeletal disorders as well as programs for reducing back pain. In addition, relationship conflicts may be relieved by increasing job autonomy as much as possible, by granting autonomous control of working hours and bus headways, as well as by banning long work hours. Moreover, various club activities, exercise programs, and counseling programs that workers can be involved in together may be beneficial. This study is significant in that it identified the relationship of the bus drivers' emotional labor and job stress, which has previously been ignored as a research topic. Through its results, this study provides baseline data for the preparation of management strategies that can address the job stress of bus drivers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6627-6640
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• 2015

This study was performed to determine the complaint rates of musculoskeletal symptoms and its association with related factors among manufacturing workers. The self-administered questionnaires were given to 856 male with 50 or less employees in manufacturing industries. As a results, complaint rates of work-related musculoskeletal symptoms of the body sites was 61.2% for shoulders, 55.4% for low back, 55.3% for neck, 38.6%, for legs/feet, 32.2% for hands/wrists/fingers and 26.9% for arms/elbows. In logistic regression analysis of significant factors related with musculoskeletal symptoms of body sites, neck was related with marital status, subjective health status, smoking, drinking coffee and occupational stress, shoulders was related with job tenure, shift work, visiting out-patient department and occupational stress, arms/elbows was related with sleeping time, experience of sick absence and occupational stress, hands/wrists/fingers was related with age, smoking, drinking coffee, working hour, job position, job tenure, visiting out-patient department and occupational stress, low back was related with educational level, BMI, sleeping time, job position, job tenure, visiting out-patient department and occupational stress and legs/feet was related with marital status, job position, job tenure, history of hospitalization and occupational stress.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.5-14
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• 2010

The paper processed settlement analysis using Finite Elements Method(FEM). Because Stress Distribution Ratio has to be decreased, for settlement analysis of soft clay deposit improved by sand compaction piles(SCP). Back analysis was processed comparing the measured settlements of laboratory model tests and finite element analysis where the SCP treated area was assumed as mixed ground with clay deposit rather than being a composite ground. The paper proposes a methodology which employs a compression index($C_c$) for settlement analysis of soft clay deposit improved by sand compaction piles from the back analysis. This approach is applied to a field measurement case(A revetment founded on the SCP improved clay deposit with the replacement ratio of 45%).

• The Korean Journal of Pain
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• v.18 no.2
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• pp.251-254
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• 2005

Spondylolysis, also known as stress injury of pars interarticularis, is a common cause of back pain in athletes, particularly children and young adults. Repeated minor traumas during flexion and extension of the spine are thought to result in bony failure due to excessive bone resorption. These lesions are common in the low back, with the majority found at the L5 vertebra. In the majority of cases of spondylolysis, non-operative treatments are recommended, such as NSAIDs, physiotherapy and bracing. Only if symptoms do not respond to conservative treatments should surgical intervention be considered. Recently, pars interarticularis injections for diagnostic and therapeutic purposes have been found to allow significant pain relief from spondylolysis for long periods. Here, the case of a 57-year-old man with spondylolysis, who suffered from back pain, which was not relieved by an epidural steroid injection, but in whom pars interarticularis injections of local anesthetic and steroid induced complete transient pain relief, following by moderate long-term relief, is presented.

• Transactions of Materials Processing
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• v.30 no.3
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• pp.134-141
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• 2021

In order to improve excessive spring-back behavior as a result of the roll forming process using ultra high strength steel (UHSS) sheet, local softening in region of a partial area expected to be deformed on an initial blank is considered in this study. With SPFC1470 UHSS sheet with initial blank thickness of 1.20mm, the local softening is performed with the following conditions: temperatures of 500℃, 550℃, 600℃ and 650℃, and holding time of 20s, 40s, 80s and 160s. Mechanical properties, such as yield stress and tensile strength, as well as elongation, are evaluated through uniaxial tensile tests, while the microstructural characteristics as a result of local softening are also investigated using the heat-treated specimens. As a result, it is shown that the spring-back behavior of the roll-formed prototype was reduced about by 78.9%, when the local softening at about 500℃ was performed for 160s considering the practical manufacturing condition.