• Journal of Korean society of Dental Hygiene
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• v.14 no.6
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• pp.795-804
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• 2014

Objectives: The purpose of the study was to investigate the relationship between the oral contraceptive pill and periodontal disease in Korean women aged from 19 to 50 years old. Methods: This study selected 1,579 women of childbearing age from 19 to 50 years old from the 5th National Health and Nutrition Survey data analysis(phase 3, 2012) taking the oral examination. The questionnaire consisted of socioeconomic demographic characteristics, health behavior, use of oral contraceptive pills, and periodontal disease. Socioeconomic demographic characteristics included age, marital status, education, monthly income, and vocation. The health behavior included obesity, stress, smoking, subjective oral health status, use of dental floss, tooth brushing, and diabetes mellitus by fasting blood sugar level. Use of oral contraceptive pills was recorded by monthly use and duration. The periodontal disease was documented by yes or no and selected as dependent variable by logistic regression analysis. Results: After revising the taking period of oral contraceptive pill for this study, there was the correlation between the prevalence of periodontal disease and odds ratio(95% CI) 1.288(1.027-1.617). Conclusions: This study will contribute to the direction of policy for an oral contraceptive pill and provide the basic data for counseling for the oral health and the side effects of oral contraceptive pills.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.5
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• pp.27-35
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• 2000

This paper deals with a control strategy for constant output power of SSRT(Soft Switching Resonant Type) FB(Full Bridge) DC-DC converter by an improved phase shift controller. When the FB DC-DC converter for the high density and the high effect control is operated in high speed switching, the switching loss and switching stress of the switching devices are increased. So, the soft switching method, which has the phase shift control with the digital I-PD controller, must be use in order to reduce its. And the output voltage that controlled by the digital I-PD controller tracks a reference without steady state error in variable input voltage. The validity of control strategy that proposed is verified from simulation results and experimental results by the DSP(TMS320C32).

• Korean Journal of Health Education and Promotion
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• v.24 no.2
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• pp.29-44
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• 2007

Objectives: The administrative employees of government were analyzed on their levels of fatigue symptoms to reveal the various factors related to them. Methods: The self-administered questionnaires were performed, during the period between Dec. 5th, 2005 and Jan. 31st, 2006, to 1,005 individuals in the service of general administration located in Daejeon Metropolitan City. The survey items included subjects' socio-demographic and job-related characteristics, health-related behavior, degree of job demand, job autonomy, social support in work, type A behavior pattern, locus of control, sense of self-esteem, and degree of fatigue. The study results were analyzed and the authors came to the following major findings, by univariate and multiple regression analysis with degree of fatigue dependent variables and other variables independent. Results and Conclusions: The study results indicated that the level of fatigue symptoms is so complicatedly influenced by variable factors as well as job-related characteristics such as socio-demographic characteristics, rank in work, or job career, to a greater extent, by job specifications and personality traits(type A) like whether performing health-related behavior or not, job demand, job autonomy, social support in work, or sense of self-esteem. Thus the effective strategy for stress reduction among governmental employees requires additional programs focusing on innovated job specifications and managed personality trait.

• Safety and Health at Work
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• v.9 no.2
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• pp.216-223
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• 2018

Background: Many studies have reported negative psychological or physical effects of emotional labor. Relationship between work-related musculoskeletal disorder and psychosocial factors has been reported. To manage organizational and psychosocial factors of musculoskeletal disorder with work place intervention among emotional laborers, the factors contributing to musculoskeletal pain must be identified and clarified. Methods: Data from the fourth Korean Working Conditions Survey was analyzed. Based on the questionnaire, we selected emotional laborers and included 3,979 participants, excluding participants whose variables were of interest to the researcher. Weight variable was applied. The association with musculoskeletal pain and psychosocial factors, such as workload, monotonous work, job control, social support, and job satisfaction, was investigated. Results: Univariate analysis demonstrated that there was a statistically significant relationship between social support, job satisfaction, and musculoskeletal pain. In multivariate analysis, job satisfaction showed a strong correlation with musculoskeletal pain at all sites. Social support was significantly associated with backache. Monotonous work seemed to reduce the pain in the neck and/or upper limbs. Job control and work intensity were not significantly associated with musculoskeletal pain. Conclusion: In this study, job satisfaction was significantly associated with musculoskeletal pain, and social support among the social psychological stressors could reduce musculoskeletal pain. However, unlike previously known, the presence of monotonous work resulted in reduced musculoskeletal pain. The results of this study will help to establish the direction of improvement of atmosphere in the workplace to prevent the musculoskeletal pain of emotional laborers.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.67-74
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• 2014

An inverter scroll compressor is used for the air conditioning in cars. Scrolls would be changed from the aluminum material to the magnesium material in order to satisfy the light weight trends of cars. The material changing influences on the scroll dimensions particularly the gap between two scrolls. Since the larger gap declines the performance of the compression, the gap between wraps of scrolls or the gap between wraps of scrolls to the plate of the opposite scroll is regarded as an important design variable. This paper is focused on the effects of the thermal stress due to the materials changing. The temperature difference between the inlet and the outlet is about 60 degrees and the highest operating temperature in the compressor is less than 110 degrees. The level of thermal stresses in the magnesium scroll is less than the result from aluminum one. The trend of the deformation is revealed that the normal directional deformation is 2 times lager than the in-plane directional deformation. Therefore the gap between the top of the wrap to the plate of the opposite scroll become more important than the other gaps. The orbiting scroll deforms larger than the fixed scroll by the thermal stresses. The deformation of the magnesium scroll is about 10% lager than that of the aluminum scroll. This value is similar to the ratio of the coefficients of thermal expansion of two materials. At the initial design stage, the results give many useful guides to engineers to propose gaps between parts.

• Computational Structural Engineering
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• v.9 no.3
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• pp.169-177
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• 1996

The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear programming formulation of the topology problem is presented. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibrium equations as equality constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minimum weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.238-248
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• 2014

The metalloid arsenic (Z = 33) is considered to be a significant potential threat to human health due to its ubiquity and toxicity, even in rural regions. In this study a rural region contaminated with arsenic, located at longitude $85^{\circ}$ 32'E and latitude $25^{\circ}$ 11'N, was initially examined. Arsenic tolerant bacteria from the rhizosphere of Amaranthas viridis were found and identified as Bacillus licheniformis through 16S rRNA gene sequencing. The potential for the uptake and removal of arsenic at 3, 6 and 9 mM [As(V)], and 2, 4 and 6 mM [As(III)], and for the reduction of the above concentrations of As(V) to As(III) by the Bacillus licheniformis were then assessed. The minimal inhibitory concentrations (MIC) for As(V) and As(III) was determined to be 10 and 7 mM, respectively. At 3 mM 100% As(V) was uptaken by the bacteria with the liberation of 42% As(III) into the medium, whereas at 6 mM As(V), 76% AS(V) was removed from the media and 56% was reduced to As(III). At 2 mM As(III), the bacteria consumed 100%, whereas at 6 mM, the As(III) consumption was only 40%. The role of pH was significant for the speciation, availability and toxicity of the arsenic, which was measured as the variation in growth, uptake and content of cell protein. Both As(V) and As(III) were most toxic at around a neutral pH, whereas both acidic and basic pH favored growth, but at variable levels. Contrary to many reports, the total cell protein content in the bacteria was enhanced by both As(V) and As(III) stress.

• Geotechnical Engineering
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• v.11 no.2
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• pp.51-70
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• 1995

Types of foundation of high rise buildings are primarily determined by loads transmitted from super structure, soil bearing capacity and available construction technology, The use of deep foundation of the buildings considered in this study due to the fact that rock of enough bearing capacity is not found down until 90~l00m. When a concentration of high soil pressure must be distributed over the entire building area, when small soft soil areas must be bridged, and when compressible strata are located at a shallow depth, mat foundation may be useful in order to have settlement and differential settlement of variable soils be minimized. The concept of mat foundation will also demonstrate some difficulties of applications if the load bearing demand directly carried down to the load -bearing strata exceeds the load -bearing capacity. This paper introduces both the analysis and design of mat type foundation for high rise buildings as well as the method-ology of modelling of the soil foundation, especially, engineered to redistribute the stress exceeding the soil bearing capacity. This process will result in the wide spread of stresses over the entire building foundation.

• Korean Journal of Health Education and Promotion
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• v.17 no.2
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• pp.229-237
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• 2000

The purpose of this study was to be useful in working out plans for improving national health by identifying public workers' knowledge of and attitude to smoking, actual conditions of smoking within nonsmoking areas, and related factors. For the purpose, the questionnaire was carried out with 761 public officials of the division manager-level and lower working in Taegu Metropolitan City Hall in september, 1998. The results are summarized as follows; Smokers of the subject group accounted for 55.1％, and the smoking rate had a significant relation with age and religion. In view of the time when smokers started smoking, smokers who started smoking after graduation from a high school accounted for 70.6％. Smokers who smoke one pack of cigarettes per day and a cigarette to its two-thirds length was the most. In the smoking place of smokers at home, 54.9％ of the smokers responded that they smoke in an outdoor space The rate of smoking in an office was 68.3％ and the rate of smoking within the nonsmoking areas of other public institutions was 43.0％. The results of multiple regression analysis with the actual state of smoking within the nonsmoking area of other public institutions as an independent variable revealed that smokers who check for a nonsmoking area before smoking in the public institutions and who do not smoke in an office do not smoke within the nonsmoking areas of other public institutions. In conclusion, more smoking and health education for public workers is needed to reduce the rate of national smoking and allow people to have a good smoking attitude, and it is required to arrange an institutional system who can strictly control public workers' smoking in their offices or public places and to stress a function of surveillance and monitoring by nonsmokers.

• Journal of the Ergonomics Society of Korea
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• v.27 no.3
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• pp.81-92
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• 2008

Musculoskeletal disorder (MSD) problems have been increasingly reported in hospital sector but the problems were not addressed with respect to holistic aspects of the target population in Korea. Often, it is required to understand how MSD symptoms are associated with factors such as personal, work environmental and psychosocial stressors. To examine features of association between sets of MSD symptoms and the factors, a questionnaire survey was conducted in a university hospital. A 140-item questionnaire was developed and used for collecting information including factors (e.g., job/occupation, task/activity, job stress) and MSD symptoms. A total of 1,091 workers (male 23.7% and female 76.3%) were finally determined for data analyses. Prevalence rate for the whole body was 72% and, among body parts, the highest was 48.7% for the shoulder, followed by 34.6%(the low back), 32.7%(the leg/foot), 27.9%(the neck), 26.7%(the wrist) and 12%(the elbow). The symptoms were significantly different by job/occupational variable in each of all body parts except the neck. The symptoms were very significantly different by task/activity variables in each of all body parts while those symptoms were significantly different by psychosocial variables, depending on body part and gender. In the logistic regression analyses performed for MSD symptoms by body part and each of 3 factors, odds ratio values varied, ranging from 0.7 to 3.3. The controls for reducing the symptoms were discussed on the basis of the findings. The results show that the MSD symptoms can remarkably vary by the factors and, in particular, can be highly differential for the task/activity factor. This study suggests that MSD symptom features be examined by using various factors and then a higher differential factor be primarily utilized for controling MSD symptoms in general industry including hospital settings.