• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.84-91
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• 2017

Recent years have witnessed the increased usage of flammable metals, such as aluminum or magnesium, in wide range of high-tech industries. These metals are indispensable for the improvement of physical properties of materials as well as the design capability of the final product. During the process, unwanted metal dusts could be released to the environment. This can lead to an occupational health and safety issues. Due to their flammable nature, more serious problem of an explosion can happen in extreme cases. The explosion is the combustion of tiny solid particles and vapor mixture, caused by pyrolysis. This complex composition makes engineering analysis more difficult, compared to simple gas explosions or vapor cloud combustions. The study was conducted to assess this light metal dust explosion in an effort to provide the bases for a risk assessment. Dust explosion characteristics of each material was carefully evaluated and an appropriate analysis tool was developed. A comprehensive database was also constructed and utilized for the calibration of the developed response model and the verification for its accuracy. Subsequently, guidelines were provided to prevent dust explosions that could occur in top-notch industrial processes.

• Journal of Preventive Medicine and Public Health
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• v.36 no.4
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• pp.390-398
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• 2003

Objectives : To evaluate the degree of adolescent internet addiction, and investigate its relationship to the general characteristics, internet environments, and contents, especially the stress measured by the psychosocial wellbeing index-short form(PWI-SF). Methods : The data was obtained from self-administered questionnaires from 886 11th grade urban area students. The questionnaires consisted of general characteristics, internet user's environments, frequencies by internet contents, internet addiction test and PWI-SF. Results : The possible rate of internet use at home was 95.1%, and the area of most internet use was the home. The frequencies of internet game and porno site use were higher in males, with web searching and community uses higher in females. The total mean of internet addiction score was 56.8, and was higher for male than for female students. From multiple regression, as analyzed by the internet addiction score as a dependent variable, on-line friends, internet use times, years of internet use, frequencies of internet game, & porno site use, and PWI-SF scores were significant in male. Internet use times, the frequencies of internet game, chatting, community use, and PWI-SF score were significant in female. Four PWI-SF subscales(social role & self reliability, depression, general health & vitality, and sleep disturbance & anxiety) and internet addiction were significantly correlated in both male and female students, with depression having the most correlation. Conclusion : The results of this study suggest that intervention should be provided to prevent internal addiction, especially for coping with stress in Korean teenage students.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.1
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• pp.12-20
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• 2020

Purpose: This study was designed to analyze the relationship between the presence and severity of depression and chewing problems (CPs) in a representative sample of the general population. Materials and Methods: Health surveys and examinations were conducted on a nationally representative sample (n = 8150) of Korean was conducted. CPs was determined by a simple survey response concerning "Do you feel uncomfortable about chewing your food because of problems with your mouth such as teeth, dentures and gums?" Depression was defined as individuals with a total score ≥ 10 on the Patient Health Questionnaire (PHQ)-9 survey. Data regarding demographics, socioeconomic history and comorbid health conditions were used to analyze adjusted logistic regression models. Results: In the Korean population, the prevalence of depression was significantly greater in individuals with CP (17.2%) than in those without CP (10.2%). On multivariate logistic regression analysis, the presence of depression was significantly associated with CPs (adjusted odd ratio [aOR]: 1.90, P < 0.001). The risk of CPs increased with increasing severity of depression as follows: severe depression (OR: 2.62, P < 0.001), moderately severe depression (OR: 2.19, P < 0.001). Conclusion: The presence of depression was significantly associated with CPs, especially in severely depressed individuals. Depression screening should be considered in treating CP patients.

• Korean Journal of Health Education and Promotion
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• v.23 no.3
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• pp.17-35
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• 2006

Objectives: This study was conducted to investigate the determining factors that have influence on elementary students who go without breakfast and identified their physical, mental and social health that may resulted by skipping breakfast. Methods: For data collection, total 855 elementary students at the 5th and 6th grade in an urban and a rural area were asked to join the survey using a self-administered questionnaire from March 25 to April 9, 2005. The data were analyzed through a series of statistical methods including frequency, percentage, chi-square$(X^2)$ test, t-test and multiple logistic regression analysis. Results: It was found that 24.0 % of respondents would skip breakfast, and influential socioeconomic factors on their skipped breakfast were economic level and mother's occupation. A group that has meals more with family everyday and a group that has breakfast served by mother as usual showed significantly low percentage of going without breakfast at statistical level(p<0.05). In case that other family members used to go without breakfast, there was a tendency to significantly high rate of skipped breakfast(p<0.01). And a group who got up early in the morning and a group who scored high points in the assessment of dietary habit showed significantly low percentage of skipped breakfast(p<0.01). In the result of multiple logistic regression analysis, the significant variables in urban area were economic level, person setting up breakfast, getting-up time and family members who would skip a meal. In rural area, meal-skipping family member, person setting up breakfast and dietary habit were significant variables(p<0.05). In physical influences according to skipping breakfast, students would skip breakfast had more stomach or dizziness(p<0.05). Depression score were higher and school life score were lower in group skipping breakfast, but not statistically significant. Conclusions: In conclusion, in order to reduce the rate of elementary students who often go without breakfast, it is favorable that they should be instructed in the importance of breakfast and the harm of skipped meal, so that they can cultivate positive living habits and dietary attitudes as well. And it is necessary that this health education cover not only students but also all of their family members(especially mother). Furthermore, it is necessary to develop systematic programs for them to get over environment factors.

• Journal of Preventive Medicine and Public Health
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• v.30 no.1 s.56
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• pp.31-43
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• 1997

Obesity usually is defined as the presence of and abnormally amount of adipose tissue. In many epidemiologic study, obesity as a health risk factor has been estimated by Body Mass Index(BMI) in general. This study was conducted to review of body fat percent measured by Bioelectric impedance analyzer as a estimator of obesity in a rural adult population. The study subjects were 421 men and 664 women who reside in the area on the Juam lake. They were sampled by multistage cluster sampling. Their mean age was 59 years old. Body fat percent increased with age, but BMI decreased with age in this study. Body fat percent was more larger at female and elder on the same BMI. The correlation coefficient between with body fat percent and body mass index was low (r=0.4737). Body fat percent was explained by not only BMI but also sex and age $(r^2=0.63)$. The result suggested that it is inadequate for BMI only to estimate obesity about elderly person who reside in the rural community. The relation of body fat percent and body mass index of this study agreed with the preceding know-ledges and studies in general.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.479-483
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• 2009

서론: 최근 음주가 사회적 문제로 더욱 심각하게 인식되고 있는 가운데 우리나라의 음주 소비량은 점점 증가하고 있는 추세이다. 또한 빠른 사회경제적 변화는 새로운 도덕과 가치의 변화를 가져왔으며 알코올 소비량의 증가와 관계가 있다.(양정남, 1998) 특히 결혼 및 배우자 유무는 음주에 중요한 관련 요인이라는 주장이 있음에도(김태수 등, 2003) 실증적인 연구는 미흡한 실정이다. 따라서 본 연구는 결혼 후 배우자 유무와 음주 형태의 관련성을 파악하고 음주 관련 교육 자료로 활용하고자 한다. 연구방법: 연구 대상자는 2005년 국민건강영양조사에서 40대 이상의 남녀 중 결혼 경험이 있는 14,970명 중 음주행태에 관한 설문에 응답한 3,190명이었으며, 결혼 후 배우자의 유무에 따른 고위험 음주 경험 및 다빈도 음주, 음주자제빈도, 고위험음주빈도와의 관련성을 통계 분석하였다. 연구결과: 결혼 후 배우자 유무에 따른 음주 행태의 연구 결과는 다음과 같다. 연구대상자의 일반적 특성은 남자 1,678명(52.6%)이며, 여자 1,512명(47.4%)였다. 연령별로는 65세 미만 2,359명(73.9%), 65세 이상 831명(26.1%)이었다. 결혼상태는 유배우 2,621명(82.2%), 사별 344명(10.8%), 이혼 및 별거 225명(7.1%)이었다. 고위험 음주경험은 한달에 한번 미만 1,883명(59.0%), 한달에 한번 정도 379명(11.9%), 일주일에 한번 이상 928명(29.1%)으로 한달에 한번 미만 고위험 음주를 경험한다가 가장 많았으며, 일주일에 한번이상. 일주일에 한번정도 순으로 고위험 음주를 한다고 응답하였다. 월평균 음주 횟 수에 있어서는 5회 이하 1,149명(36.0), 6회-10회 395명(12.4%), 11회이상 593명(27.7%)이었다. 고위험 음주 경험을 종속변수로 한 로지스틱 회귀분석에서 여자보다 남자가 고위험 음주 경험을 많아 하며, 연령이 증가하면 고위험 음주음 경험이 낮아지며, 교육수준이 높아지면 고위험 음주 경험은 낮아지는 것으로 나타났다. 음주자제 경험 종속변수로 한 로지스틱 회귀분석에서 여자보다 남자가 음주자제 경험을 많아 하며, 연령이 증가하면 음주자제 경험이 낮아지며, 교육수준이 높아지면 음주자제 경험은 낮아지는 것으로 나타났다. 다빈도 음주 경험 종속변수로 한 로지스틱 회귀분석에서 여자보다 남자가 다빈도음주 경험을 많아 하며, 연령이 증가하면 다빈도 음주 경험 높아지며, 가구 평균 소득이 증가 하거나, 교육수준이 높아지면 다빈도 음주 경험은 낮아지는 것으로 나타났다. 논의 및 결론: 결혼 후 배우자 유무와 고위험 음주는 남녀를 합친 전체와 남자에게서 통계적으로 유의하였으며, 음주자제빈도에서는 남녀를 합친 전체에서 통계적으로 유의하였다. 또한 다빈도 음주에서 여자에게서 통계적으로 유의하였다. 이러한 결과는 절주사업 기초자료로 활용될 수 있는 가능성을 확인하였으며, 추가적인 연구의 필요성을 시사하였다.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.755-758
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• 2009

본 연구는 요양보호사들의 직무스트레스가 직무만족도에 미치는 영향을 알아보고자 하는 연구로 연구대상은 대전지역의 요양시설에 근무하는 요양보호사 302명을 대상으로 2008년 10월 6일부터 10월 30일 까지 구조화된 설문지를 이용하여 다음과 같은 결론을 얻었다. 연구 대상자의 직무스트레스에 대한 요인은 총 4개로 요인별 평균값은 환자관련이 2.38(표준편차 1.27), 업무관련 2.27(표준편차1.23), 대인관계 2.04(표준편차 1.01), 경제적인면 2.09(표준편차 1.17)로 나타났다. 연구 대상자의 직무만족에 대한 요인은 총 2개로 요인별 평균값은 업무자체에 대한 만족여부가 3.36(표준편차 0.690), 이직의사 2.36(표준편차 0.796)으로 나타났다. 업무에 대한 만족여부는 환자관련(P=0.021) 스트레스와 업무관련(P=0.014)스트레스가 유의하게 나타났고, 이에 대한 영향으로는 연령에서 50대(P=0.002), 40대(P=0.008), 20대(P=0.030), 종교를 가지고 있는 그룹(P=0.041), 근무동기로는 일에 대한 보람(P=0.042), 경력은 3년이상(P=0.002), 6개월이상 1년미만(P=0.006), 6개월미만(P=0.002)인 그룹, 소유자격증에 관해서는 간호사(P=0.009)면허 소지 그룹, 돌보는 환자수로는 1~5명(P=0.034), 6명~10명(P=0.001), 근무시간은 24시간(P=0.000)근무와 8시간 교대근무(P=0.026)가 유의한 영향을 주는 것으로 나타났다. 5. 이직의사 여부에서 요인2.업무관련(P=0.002)스트레스 유의하게 나타났고, 이에 대한 영향은 무교(P=0.010)인 그룹, 근무동기로는 미래에 대한 준비(P=0.012), 월급여로는 100만원~149만원(P=0.030), 돌보는 환자수로는 6명~10명(P=0.020)이 유의한 영향으로 나타났다.

• Journal of Conservation Science
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• v.25 no.4
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• pp.399-409
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• 2009

Outdoor iron artefacts are easily corroded by affection of environmental pollutants directly. Especially they need to be removed $Cl^-$ ions, but outdoor iron artefacts are excluded for desalination owing to their special features. Therefore this study contains the conservation processes of an iron stele of the Joseon Dynasty as the sample as well as desalination experiments that were carried out the desalting method using spill pads and the immersion desalting method together in order to compare. Desalting methods were compared by analyses such as an optical and metallurgical microscope, SEM-EDS, pH meter, Ion Chromatography and X-ray diffraction. As a result of the analysis, the optical and metallurgical microscopy show that the corrosion products are constituted by the layers and the metallurgical microstructure is a white cast iron. The SEM-EDS results of corrosion products detected mainly Fe, O, and especially Cl upto 2.48wt%. The results of pH and anion analysis for the washing solution, the desalting method using spill pads shows the similar effect to the immersion desalting method. As a result of XRD analysis before and after desalting corrosion products, goethite, magnetite, lepidocrocite and akaganeite are detected before desalting, but akaganeite is not detected after desalting at the desalting methode using spill pads, which indicates to have an effect on desalination. Therefore the results show that the desalting method using spill pads has an effect on desalination similar to the immersing desalting method.

• Korean Journal of Food Science and Technology
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• v.39 no.3
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• pp.246-254
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• 2007

Fresh tea leaves grown in Jeju Island and Jeonnam Province of South Korea were plucked and processed. Volatile compounds (VCs) were analyzed and identified with SPME-GC/GC-MS/GC-O. The VCs of green teas were classified into two major categories based on their aroma characteristics: the Greenish (Group I), and Floral (Group II) odorants. It was found that the VCs were decreased significantly in fresh tea leaves as they were plucked at the later stages of cultivation. The ratio of VCs responsible for Group I and Group II compounds was well-balanced in tea leaves plucked in May, but the balances were changed when the fresh leaves were processed. The major VCs of fresh tea leaves in Jeju and Jeonnam were n-hexanal, E-2-hexenal, Z-3-hexenal, myrcene, benzyl alcohol, linalool, and phenyl alcohol. Also, Jeju and Jeonnam tea leaves had different aroma composition. n-Heptanol, ${\beta}-pinene$, benzaldehyde, and ethyl salicylate were found in Jeju fresh tea leaves, and Z-3-hexenol, E-2-hexenol, and methyl n-heptanoate were detected in Jeju dry tea leaves. On the other hand, Z-linalool oxide and myrcene were found in Jeonnam dry tea leaves. The SPME-GC method showed high reproducibility (RSD, 7.4%) with no-artifact formation. In this study, optimum plucking period of tea leaves could be determined for production of high quality green tea with a well-balanced aroma and characteristic VCs in green tea according to growing areas.

• Journal of Conservation Science
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• v.28 no.3
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• pp.257-264
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• 2012

Ancient mirrors are generally made of bronze, and it is very rare to find cases of iron mirrors excavated domestically. In this study, the unidentified ferrous artifact was treated for conservation, and was identified as a mirror. In this process, the sample was taken and analyzed for microstructure, and the manufacturing technology was studied. Analysis involved optical microscope, micro-hardness tester, and SEM-EDS. As the result of analysis, iron mirror structure exist not almost non-metallic inclusions, and partially network cementite was observed. This appears to have been caused by reduced carbon content due to decarburizing the cast iron in the solid state mirror which was created by cast iron. The ledeburite structure of the casting has difficult to cut or polish because has great hardness by high carbon content. Thus, the cast iron mirror was decarburized at a temperature under $850^{\circ}C$ with CO or $CO_2$ blocked, which reduced the hardness of the iron mirror and made it possible to polish the mirror surface. This deformation of structure according to carbon content results from such manufacturing technology.