• Composites Research
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• v.19 no.6
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• pp.1-7
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• 2006

This is the preliminary study to develop composite window frame of commercial aircraft using VaRTM process. For two candidate carbon fabrics(triaxial overbraid, sleeving braider), specimens were fabricated using VaRTM process, and the physical & mechanical property tests were performed to obtain the material properties according to ASTM. FEM analysis for each candidate carbon fabric was performed to find the minimum number of plies and weight for composite window frame to satisfy the design requirements. In this study, Tsai-Wu strength failure criterion was used to evaluate the safety of structure.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.269-274
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• 2003

This experiment was carried out to investigate the effects of different IVM-IVC culture media factors, such as development rates according to the maturation media, collecting times from slaughter to initiation of incubation and with cumulus cells, on in vitro maturation of oocytes collected from 3∼5mm diameter follicles of the swine abattoir The development rates significantly(p<0.05) higher when the oocytes were matured TCM-199 media than NCSU-23 media. In comparing with TCM199 medium in presence of Earle's salts and Hank's salt, there were no significantly differences between each salt balance in cleaved rate and in number of morulae plus blastocyst. Among 1,455 immature oocytes, 999(68.6％) of oocytes were cleaved. The number of development to the morulae and blastocysts were 617(61.8％) include 62 balstocysts(6.2％).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.547-555
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• 2014

Objective: This study was conducted to investigate the association between subjective distress symptoms and argon welding among workers in Gyeongnam Province shipyard. Method: 31 argon and 29 non-argon welding workers were selected as study subjects in order to measure concentrations of personal dust, welding fumes and other hazardous materials such as ZnO, Pb, Cr, FeO, MnO, Cu, Ni, $TiO_2$, MgO, NO, $NO_2$, $O_3$, $O_2$, $CO_2$, CO and Ar. An interviewer-administered questionnaire survey was also performed on the same subjects. The items queried were as follows: age, height, weight, working duration, welding time, welding rod amounts used, drinking, smoking, and rate of subjective distress symptoms including headache and other symptoms such as fever, vomiting and nausea, metal fume fever, dizziness, tingling sensations, difficulty in breathing, memory loss, sleep disorders, emotional disturbance, hearing loss, hand tremors, visual impairment, neural abnormality, allergic reaction, runny nose and stuffiness, rhinitis, and suffocation. Statistical analysis was performed using SPSS software, version 18. Data are expressed as the mean ${\pm}SD$. An ${\chi}^2$-test and a normality test using a Shapiro wilk test were performed for the above variables. Logistic regression analysis was also conducted to identify the factors that affect the total score for subjective distress symptoms. Result: An association was shown between welding type (argon or non-argon welding) and the total score for subjective distress symptoms. Among the rate of complaining of subjective distress symptoms, vomiting and nausea, difficulty breathing, and allergic reactions were all significantly higher in the argon welding group. Only the concentration of dust and welding fumes was shown to be distributed normally after natural log transformation. According to logistic regression analysis, the correlations of working duration and welding type (argon or non-argon) between the total score of subjective distress symptoms were found to be statistically significant (p=0.041, p=0.049, respectively). Conclusion: Our results suggest that argon welding could cause subjective distress symptoms in shipyard workers.

• Journal of Preventive Medicine and Public Health
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• v.27 no.4 s.48
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• pp.677-691
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• 1994

To evaluate the validity of serum pepsinogen levels as a screening tool for gastric cancer and adenoma, immunoradiometric assays of serum pepsinogen I level (PG I), II level (PG II) and esphagogastroduodenal endoscopies were done in 757 health examinees. Serum PG I level was higher in subjects with active duodenal ulcer (n=45, $75.2{\pm}34.3{\mu}g/l(mean{\pm}standard\;deviation)$, p<0.01) and gastroduodenal ulcers (n=8, $75.6{\pm}19.8{\mu}g/l$, p<0.05), and was lower in those with gastric adenoma(n=4, $37.7{\pm}37.2{\mu}g/l$, p<0.2) than those with normal, mild gastritis findings or ulcer scars (n=378, $56.6{\pm}24.9{\mu}g/l$. Serum PG II level was higher in subjects with active duodenal ulcer($17.2{\pm}13.8{\mu}g/l$, p<0.2), active gastro-duodenal ulcers ($18.3{\pm}7.4{\mu}g/l$, p<0.2) and gastric carcinoma (n=3, $23.8{\pm}10.9{\mu}g/l$, p<0.05) than those with normal, mild gastritis findings or ulcer scars $(14.5{\pm}7.9{\mu}g/l)$. Serum PG I/PG II ratio was higher in subjects with active duodenal ulcer($5.1{\pm}1.6$, p<0.05) and was lower in those with chronic gastritis(n=107, $4.1{\pm}1.7$, p<0.05), gastric polyp(n=19, $3.9{\pm}1.4$, p<0.2), gastric adenoma(n=4, $2.1{\pm}1.9$, p<0.01) and gastric carcinoma(n=3, $2.7{\pm}1.2$, p<0.1) than those with normal, mild gastritis findings or ulcer scars ($4.5{\pm}1.7$). Serum PG II level increased with age until 6th decade, whereas serum PG I/PG II ratio decreased with age in 378 subjects with normal, mild gastritis findings or ulcer scars. The screening criteria of serum PG I<$70{\mu}g/l$ and PG I/PG II ratio<3.0 for detecting gastric cancer and adenoma gave a positive rate of 15.7%, sensitivity of 57.1% and specificity of 84.7%.

• Journal of Preventive Medicine and Public Health
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• v.36 no.3
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• pp.248-254
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• 2003

Objective : This study was conducted in order to investigate predictors of smoking cessation in outpatients. Method : Subjects were 40f adult smoking patients who saw their doctors in the outpatient setting at a university hospital, regardless of their willingness of otherwise in smoking cessation. Physicians delivered a brief, stop smoking prompt to all patients who smoked one or more cigarettes a day. Then they referred to on-site counselors who provided a brief, nurse assisted intervention with a survey to a randomly assigned intervention group (200 smoking patients), whom the counselors telephoned later to prevent relapse or promote the motivation to quit, or gave only a survey to a control group (201 smoking patients). After at least 5 months, self-reported current smoking cessation was confirmed later using cut-off values of 7 ppm or less in expired alveolar air after breath holding portable CO analyzer. Results : After 5 months, subjects in the intervention group were 1.56 times (95% C.I. 0.89-2.73) more likely to quit smoking than those in the non-intervention group (14.0% vs. 9.0%). Willingness to quit smoking in a month, scheduled admission in a month, self efficacy score and FTND (Fagerstrom Test for Nicotine Dependence) score were all significantly related with smoking cessation. In stepwise multiple logistic regression, previous attempts to quit smoking were significant instead of self efficacy score. In the intervention group who had willingness to quit smoking in a month (132 smoking patients), FTND score, whether quit date was today, and whether quit promise paper was submitting were all significantly related with smoking cessation. In stepwise multiple logistic regression, scheduled admission in a month and whether quit date was today were significant predictor variables, Smoking cessation treatment should be tailored to individual smoking patients considering these predictors.

• Journal of Preventive Medicine and Public Health
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• v.28 no.2 s.50
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• pp.473-486
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• 1995

A hospital-based, matched case-control study was carried out to evaluate the relation ship of various suspected risk factors including snoring and serum level of cholesterol to cerebrovascular disease in Korea. A total of 127 incident cases of cerebrovascular disease(74 cases of cerebral infarction and 53 cases of intracerebral hemorrhage) admitted to. the department of neurology in a university hospital from December, 1993 to March, 1995 were compared with 127 matched controls admitted to same hospital in same period. A multivariate analysis suggested that ECG abnormality(left ventricular hypertrophy and atrial fibrillation), family history of cerebrovascular disease, fundoscopic abnormality, previous history of transient ischemic attack and hypercholesterolemia were risk factors of cerebrovascular disease, ECG abnormality, fundoscopic abnormality, smoking and hypercholesterolemia were also suggested as risk factors of cerebral infarction.

• Journal of Preventive Medicine and Public Health
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• v.24 no.1 s.33
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• pp.93-97
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• 1991

The time honoured tuning fork at present widely available for examining vibration sensation is brought about the problem of great interobserver variation. To resolve t his problem, author developed a divice using electric magnet that stimulates constantly tuning fork. The perception time of vibration from tunung fork by this device was tested on the index finger of dominant hand of twenty eight subjects. It was 12.44 seconds on average and ranged from 9.47 to 17.25. Coefficient of variation of it was 16.89 percent. Correlation coefficient between test and retest after 30 minutes was 0.957(p<0.01). This device is portable. Test procedure in non-invasive, non-aversive and simple, can be performed within one minute, and does not require the skilled technician. It is felt that this device testing vibration perception time is suitable as screening tool for early detection of occupational peripheral neuropathy.

• Journal of Preventive Medicine and Public Health
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• v.40 no.2
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• pp.177-184
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• 2007

Objectives : This study was conducted to investigate the levels of psychosocial stress, job stress and their related factors among medical doctors practicing at local clinics. Methods : A survey using a self administered questionnaire was administered to 1,456 doctors practicing at private clinics via post for 2 months (2006. 1 - 2006. 3). Psychosocial stress, job stress, demographic factors, job related factors and health related behaviors were investigated. Among the eligible study population, the respondents were 428 doctors (29.4%). Results : The average scores of psychosocial stress and job stress were 2.19 and 3.13, respectively. The levels of psychosocial stress and job stress were statistically lower in older respondents, those who worked shorter or who were more satisfied with their job, and those with higher socioeconomic status. The level of psychosocial stress was related with smoking status, drinking status and exercise. The level of job stress was related with smoking status and exercise. In multiple linear regression analysis using psychosocial stress as a dependent variable, age, working hours per day, job satisfaction and perception on socioeconomic status were significant independent variables. In analysis using job stress as a dependent variable, age, working hours per day and job satisfaction were significant independent variables. Conclusions : Stress affects the doctor-patient relationship, productivity and overall health level of people. Therefore, it is important to manage and relieve the stress of doctors. It is suggested that more advanced studies on stress level and related factors and ways to improve the stress and health related behaviors of medical doctors should be conducted.

• Publications of The Korean Astronomical Society
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• v.36 no.3
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• pp.79-95
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• 2021

This study aims to develop a restoration model of an armillary sphere of Tongcheon-ui (Pan-celestial Armillary Sphere) by referring to the records of Damheonseo (Hong Dae-Yong Anthology) and the artifact of an armillary sphere in the Korean Christian Museum of Soongsil University. Between 1760 and 1762, Hong, Dae-Yong (1731-1783) built Tongcheon-ui, with Na, Kyung-Jeok (1690-1762) designing the basic structure and Ann, Cheo-In (1710-1787) completing the assembly. The model in this study is a spherical body with a diameter of 510 mm. Tongcheon-ui operates the armillary sphere by transmitting the rotational power from the lantern clock. The armillary sphere is constructed in the fashion of a two-layer sphere: the outer one is Yukhab-ui that is fixed; and the inner one, Samsin-ui, is rotated around the polar axis. In the equatorial ring possessed by Samsin-ui, an ecliptic ring and a lunar-path ring are successively fixed and are tilted by 23.5° and 28.5° over the equatorial ring, respectively. A solar miniature attached to a 365-toothed inner gear on the ecliptic ring reproduces the annual motion of the Sun. A lunar miniature installed on a 114-toothed inner gear of the lunar-path ring can also replay the moon's orbital motion and phase change. By the set of 'a ratchet gear, a shaft and a spur gear' installed in the solstice-colure double-ring, the inner gears in the ecliptic ring and lunar-path ring can be rotated in the opposite direction to the rotation of Samsin-ui and then the solar and lunar miniatures can simulate their revolution over the period of a year and a month, respectively. In order to indicate the change of the moon phases, 27 pins were arranged in a uniform circle around the lunar-path ring, and the 29-toothed wheel is fixed under the solar miniature. At the center of the armillary sphere, an earth plate representing a world map is fixed horizontally. Tongcheon-ui is the armillary sphere clock developed by Confucian scholars in the late Joseon Dynasty, and the technical level at which astronomical clocks could be produced at the time is of a high standard.

• The Mathematical Education
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• v.61 no.1
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• pp.47-62
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• 2022

This study investigated the contents related to the plane figures in the geometry domains of Joseon-Sanhak in the late 18th century and focused on changes in explanations and calculation methods related to plane figures, the rigor of mathematical logic in the problem-solving process, and the newly emerged mathematical topics. For this purpose, We analyzed , and written in the late 18th century and and written in the previous period. The results of this study are as follows. First, an explanation that pays attention to the figures as an object of inquiry, not as a measurement object, and a case of additional presentation or replacing the existing solution method was found. Second, descriptions of the validity of calculations in some problems, explanations through diagrams with figure diagrams, clear perceptions of approximations and explanations of more precise approximation were representative examples of pursuing the rigor of mathematical logic. Lastly, the new geometric domain theme in the late 18th century was Palsun corresponding to today's trigonometric functions and example of extending the relationship between the components of the triangle to a general triangle. Joseon-Sanhak cases in the late 18th century are the meaningful materials which explain the gradual acceptance of the theoretical and argumentative style of Western mathematics