• Journal of Korean society of Dental Hygiene
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• v.11 no.2
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• pp.179-188
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• 2011

Objectives : The study set out to analyze correlations between emotional labor and job stress among dental hygienist, who have direct and lasting relationships with patients in dental clinic, and provide basic data to resolve stressors and manage stress. Methods : A survey was taken among dental hygienists working at dental clinics, and 200 questionnaires were used in analysis. The gathered data were put to Cronbach's alpha with the SPSS WIN12.0 program to test the reliability of the inventories to measure their emotional labor and job stress. In addition, correlation analysis was conducted to examine relations between the items of emotional labor and those of job stress along with regression analysis to examine relations between emotional labor and job stress. Finally, t-test and One-way ANOVA were conducted to test mean differences in the job stress items according to the degrees of emotional labor with the statistical significance level set at 0.05. Results : 1. The measurement tool used in the study recorded 0.7 for all the areas of Cronbach's alpha for internal reliability and thus achieved high reliability. 2. The overall mean of emotional labor was 2.74, which indicates that the dental hygienists had 'average' or higher stress for emotional labor. 3. Emotional labor had statistically significant relations with educational background, place of work, motivation to choose to be a dental hygienist, and religion of their general characteristics. 4. There was statistical significance in relations between general characteristics and job stress according to educational background, position at work, and experience with change of occupation. 5. The correlations between emotional labor and the stress areas were analyzed. As a result, emotional labor was in positive(+) correlations with job demand, lack of job autonomy, relational conflict, job instability, organizational system, and corporate culture. In addition, regression analysis was conducted to test causal relations between emotional labor and job stress. The results indicate that there were positive(+) influences between emotional labor and job stress. Conclusions : The results show that emotional labor can serve as a mediating variable for job stress in dental clinic. Thus both dental clinics and dental hygienists need to have ways to deal with job stress derived from emotional labor in which they are forced to process their emotions according to the dental clinics' demands, properly. The study will hopefully trigger ongoing follow-up researches on the deployment of dental hygienists according to their job characteristics and the situational variables to alleviate the negative results of emotional labor.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.1-17
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• 2000

Carcinogen-DNA adduct analysis has potential for biomonitoring the earliest effects of exposure to many chemical carcinogens. They are the covalent reaction products of electrophiles and nucleophilic sites on DNA and the initial damage to DNA induced by many carcinogens. So many researchers begin to use them as biomarker for monitoring the earliest exposure of carcinogens and develop the effective analytical techniques about them. Randerath, Gupta and coworkers(1981, 1982) has also developed a $^{32}P$-postlabelling method as one among them. A major project for biomonitoring workers with carcinogen-DNA adducts is to develop non-invasive samples instead of tissues of target organs such as baldder and lung. This study use the exfoliated urothelial cells in urine for examine benzidine-DNA adducts. The content of exfoliated urothelial cells is not enough to significantly measure DNA content with spectrophotometer, and require the another way. So firstly washing the collected cells with PBS and 70% ethanol and centrifuge them for removing the crystals in urine, which block the isolation of DNA adducts. And then, measure the total nucleotide after $^{32}P$-postlabelling for calculating RAL. $[{\gamma}-^{32}P]ATP$ using for $^{32}P$-postlabelling, can synthesize with $[^{32}P]H_3PO_4$, and reagent and enzyme mixture (RM, EM), which is very economic in case of requiring a lot of them. Chromatography was composed of two steps. First step was to separate adduct ones from unadducted nucleotide, and secondary step was separate each adduct, which were performed with 4 kinds of solvents and different directions on TLC. With this procedure, we measure the DNA adducts in exfoliated urothelial cells of workers who were employed in benzidine and benzidine-dye company. RAL of adducts were $89.0{\times}10^7$ and $57.0{\times}10^7$ in them. In conclusion, we can significantly measure the DNA adduct in exfoliated urothelial cells by using the above $^{32}P$-postlabelling procedures, and use them to be biomonitoring workers who exposed carcinogens.

• The Korean Journal of Emergency Medical Services
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• v.13 no.1
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• pp.35-48
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• 2009

Purpose: Firefighters were subjected to be exposed to 24-hour shiftwork and high level of job stress, but there is little study of fire fighters about between Job Stress and Psychological stress in Korea. This study was performed to evaluate job stress of fire fighters grouped by different job types and analyze the health effect of job stress by using a PWI-SF(Psycho-social Well-being Index, Short Form). Methods : This study was to measure the degree of job stress and socio-psychological stress of firefighters working at 119 safety center and analyze the relationship between job stress and mental health, through self-administered questionnaire survey on 918 fire fighters working at fire department located in Korea, during October in 2008. Question items of the questionnaire consist of general characteristics, job stress, and socio-psychological stress. Job Stress Measurement Scale for Koreans was used to measure job stress, while PWI-SF used for socio-psychological stress. Collected data was analyzed through frequency analysis, ${\chi}^2$ test, one-way ANOVA, correlation analysis, multi-regression analysis using a statistic program, SPSS/10.0 Ver for Windows, and statistical significance level was 0.05. Result : Accordingly, this paper is written for the purpose of scrutinizing the reason of 119 rescuers' job stress and Socio-Psychological stress. This thesis tries to analyze a problem and provide contents through many variables concerned and theoretical investigation with the actual research of questionnaire. The results of the study are summarized as follows : Fire fighters feel relatively high stressful in their performance. Job stress, organizational commitment and burnout did not have been influence upon by individual cases such as economic condition, regular exercise etc. Finally, as a result of step by step regression analysis, the variable that can explain Socio-Psychological stress the best was negative emotion scale(NE). Conclusions : It is necessary to conduct repeated studies in the future, since the study implied that there was a contrary relationship between job stress and socio-psychological stress. In order to reduce job stress and maintain better mental health, it is more important than anything else to help firefighters have willingness and efforts to sustain a healthy life, so the development of various programs and education to raise their awareness should be implemented.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.21-31
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• 2017

Geobag method is an eco-friendly method to minimize the impact on the environment in the construction of retaining wall structure as a kind of geosynthetic reinforced retaining walls. In this study, evaluated behavior of full scaled geobag retaining wall about four different types of geobag retaining walls, that is, non-compacted geobags wall, compacted geobag wall, combination of longitudinal and transversal laied geobags wall, gabion and geobag wall were constructed in the field with instrumentation. Based on the results of field measurement, transversal layered geobag wall for non-compacted case was displaced 30% more than that of mixed gabion wall. Also, the more than 2m geobag walls without reinforcement at the backfill area are turned out to be unstable in terms of wall displacement. On the one hand, the distribution of the earth pressure for all geobag retaining walls sites show within the range of Rankine's and Coulomb's earth pressure after construction. But after intensity rainfall, the transversal laied geobag walls significantly increment of soil pressure. The geobag walls which constructed in the way of mixed wall systems such as gabion and geobag, longitudinal and transversal laied geobags are much stable with comparison of transversal laied geobag wall.

• Journal of Acupuncture Research
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• v.28 no.2
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• pp.13-25
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• 2011

Objectives : This study was accomplished to investigate the effects of acupuncture at Jeonjung($CV_{17}$) on the heart rate variability(HRV) in healthy adults. And based on that, we tried to find out how acupuncture at Jeonjung($CV_{17}$) effects on the activity and balance of the autonomic nervous system. Methods : We investigated on 74 healthy volunteers consisted of 24 subjects in acupuncture group, 24 subjects in sham acupuncture group and 24 subjects in control group. On the other hand, two volunteers were ruled out by standard of elimination. The study was established by randomized trial. Acupuncture was applied at Jeonjung($CV_{17}$) during 10 minutes in acupuncture group and minimal acupuncture was applied at the same area in sham acupuncture group. No treatment was executed in control group. We measured HRV 3 times : baseline measurement and after treatment in acupuncture group and sham acupuncture group (after rest in control group) twise. The SPSS 15.0 for Windows was used to analyze the data by paired t-test, Wilcoxon signed ranks test (in group) and One-Way ANOVA, Kruskal-Wallis test (between the groups). Results: 1. In acupuncture group, Mean HRT, PSI, Normalized HF decreased significantly. SDNN, Ln (TP), Ln (LF), Ln (VLF), Normalized LF and LF/HF ratio increased significantly. RMSSD, Ln(HF) were not affected. 2. In sham acupuncture group, all indicators were not affected. 3. In control group, mean HRT, Ln(TP) decreased significantly. SDNN, RMSSD, PSI, Ln(LF), Ln(HF), Ln(VLF), normalized LF, normalized HF and LF/HF ratio were not affected. Conclusions : We suggest that acupuncture at Jeonjung($CV_{17}$) increases the activity of autonomic nervous system and makes effects on the balance of the autonomic nervous system.

• Clinical and Experimental Pediatrics
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• v.46 no.5
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• pp.495-499
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• 2003

Purpose : Eosinophil is one of the important inflammatory cell involved in the airway inflammation in childhood asthma. It has been demonstrated that markers of eosinophil activation, including eosinophil cationic protein or eosinophil protein X(EPX), are increased in childhood asthma. Furthermore, they are related to disease activity and are assumed to be helpful in monitoring the treatment effect as urinary EPX(U-EPX) can be obtained easily and in a noninvasive way in children of all ages. Methods : Twenty-five children(22 male and three female) aged $11.87{\pm}3.82$ years with stable asthma were challenged with methacholine and urine was collected from each child during the following periods; before methacholine challenge test(MCT); 0-3 hr after the end of MCT; 4-7 hr after the end of MCT; and 8-24 hr after the end of MCT. Bronchial reactivity was determined by using Dosimeter( Jeager, Germany) with serially diluted methacholine from 0.05 to 25.0 mg. The $FEV_1$ less than 80% of baseline value were classified into positive MCT. U-EPX was measured with a sensitive and specific radioimmunoassay(Pharmacia & Upjohn AB, Uppsala, Sweden). Results were expressed as ${\mu}gEPX/mmol$ creatinine. Results : An early airway response after MCT was associated with an increase of U-EPX excretion for 0-3 hr after methacholine inhalation in comparison with beseline values. Most subjects showed a small increase in U-EPX excretion during late asthmatic response for 4-7 hr, which then decreased to normal level in 8-24 hr. Also, a tendency for a higher increase of U-EPX was associated with a lower threshold of methacholine challenge and a longer duration of asthma. Conclusion : Measurement of EPX in urine is a noninvasive and easy method to assess the severity of airway inflammation in asthmatic children. It may be a helpful index of the events underlying the airway inflammatory responses during nonspecific bronchial challenge, and in monitoring asthma management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.547-557
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• 2017

This study analyzed the differences depending on gender differences, the years for graduation, college majors, and grades by the level of students' learning process about the student engagement of college students. Subjects were 684 students who responded to a student engagement survey questionnaire among the students attending the regular curriculum at the K-college located in Geoje-si. For measurement, the college students' learning process analysis scale was modified and supplemented prior to use. Frequency analysis was adopted to search individual backgrounds of college students. One-way ANOVA and Post-hoc test were conducted in order to find differences according to gender differences, the years for graduation, college majors, and grades by the level of learning process. The study results are as follows. First, the college students' learning process on gender had significant differences in involvement in and out of instruction, teaching-learning outcomes, and college facility system and service. Second, the college students' learning process according to the years for graduation had significant differences in involvement in and out of instruction, class satisfaction, and college facility system and service. Third, the college students' learning process according to major differences had significant differences in involvement in and out of instruction, study interactions, academic achievement, and college facility system and service. Fourth, the college students' learning process according to grades had significant differences in total sub-components (involvement in and out of instruction, class satisfaction, study interactions, academic achievement, and college facility system and service). Lastly, the study discussions and implications are described.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.617-622
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• 2018

Air is essential for human beings to survive, but urban air is polluted with soot and harmful gases, due to the increase in industrial development and the population. Thus, air pollution in large cities is of increasing interest in the research community. One of the plausible solutions to this problem is supplying sufficient oxygen to indoor spaces. The main principle of the oxygen generator is to separate oxygen from air using synthetic zeolite. Various synthetic zeolites have been applied to public indoor spaces with the focus being placed on the oxygen exchange quality. Among the characteristics of zeolites which can be applied to oxygen generators is their ability to adsorb nitrogen from the air and, in this way, generate only oxygen. Thus, we investigated the degree of nitrogen adsorption by five kinds of natural zeolite and LTA zeolite 3A, 4A, and 5A (two different sizes). Using the PSA method, the higher the degree of nitrogen adsorption, the higher the oxygen saturation concentration, it was found that the nitrogen adsorption degree of the 5A zeolite was the highest. 6% on average. It was also found that the size of the zeolite had a significant effect on the degree of nitrogen adsorption.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.585-591
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• 2017

Turbocharging is widely used in diesel and gasoline engines as an effective way to reduce fuel consumption. But turbochargers have turbo-lag due to mechanical friction losses. Bearing friction losses are a major cause of mechanical friction losses and are particularly intensified in the lower speed range of the engine. Current turbochargers mostly use oil bearings (two journal bearings and one thrust bearing). In this study, we focus on the bearing friction in the lower speed range. Experimental equipment was made using a drive motor, load cell, magnetic coupling, and oil control system. We measured the friction losses of the turbocharger while considering the influence of the rotation speed, oil temperature, and pressure. The friction power losses increased exponentially when the turbocharger speed increased.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.105-115
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• 2006

The purpose of this study is to elucidate the mechanical characteristics of lower extremity joint movements at different walking speeds in obese people and suggest the very suitable exercise for obese person's own body weight and basic data for clinical application leading to medical treatment of obesity. This experimental subjects are all males between the ages of 20 and 30, who are classified into two groups according to Body Mass Index(BMI): one group is 15 people with normal body weight and the other 15 obese people. Walking speed is analysed at 3 different speeds ($1.5^m/s$, $1.8^m/s$, $2.1^m/s$) which is increased by $0.3^m/s$ from the standard speed of $1.5^m/s$. We calculated joint moments of lower extremity during stance phase through video recording and platform force measurement.Two-way ANOVA(Analysis of Variance, Mix) is applied to get the difference of moments according to walking speeds between normal and obese groups. Pearson's Correlation Analysis is applied to look into correlation between walking speeds and joint moments in both groups. Significance level of each experiment is set as ${\alpha}=.05$. As walking speed increases maximum ankle plantar flexion moment in the stance phase is smaller in obese group than in normal group, which is suggestive of weak toe push-off during terminal stance in obese group, and the highest maximum ankle plantar flexion moment in obese group during the middle speed walking($1.8^m/s.$). Maximum ankle dorsal flexion moment in obese group is relatively higher than in normal group and this is regarded as a kind of compensatory mechanism to decrease the impact on ankle when heel contacts the floor. Maximum knee flexion and extension moments are both higher in normal group with an increase tendency proportional to walking speed and maximum hip flexion and extension moments higher in obese group. In summary, maximum ankle plantar flexion moment between groups(p<.025), maximum knee moment not in flexion but in extension(p<.001) within each group according to increasing walking speed, and maximum hip flexion and extension moment(p<.001 and p<.004, respectively according to increasing walking speed are statistically significant but knee and hip moments between groups are not. Pearson correlation are different: high correlation coefficients in maximum knee flexion and extension moments, in maximum hip extension moment but not hip flexion, and in maximum ankle dorsal flexion moment but not ankle plantar flexion, in each group. We suspect that equilibrium imbalance develops when the subject increases walking speed and the time is around which he takes his foot off the floor.