• 전자공학회논문지T
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• 제36T권1호
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• pp.19-24
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• 1999

In\sub 2\O\sub 3\ 계 산화물 반도체형 후막센서의 ppb 범위의 오존에 대한 감지특성을 살펴보았다. In\sub 2\O\sub 감지막은 오존에 감도가 상당히 높았지만 안정된 신호를 얻을 수 없었다. In\sub 2\O\sub에 3wt.% 의 Fe\sub 2\O\sub 3\를 첨가한 경우에는, 순수한 In\sub 2\O\sub 와 비교할 때 응답 시간과 감도에 있어서 감지 특성의 향상이 관찰되었지만, 센서 신호가 시간에 따라 계속 증가되는 경향은 크게 개선되지 않았다. 그러나 In\sub 2\O\sub:Fe\sub 2\O\sub 3\ 혼합 분말의 열처리는 감도가 감소하기는 하였지만 센서의 오존 응답 및 회복 특성을 증진시켰다. 특히 1300℃ 정도의 고온에서 혼합 분말을 열처리 하여 제조한 감지막은 감도의 감소는 있었지만 550℃ 의 측정 온도에서 빠른 응답 및 회복 특성과 센서 신호가 최대값으로 빠르게 수렴함을 확인할 수 있었다. 또한 이들 센서는 오존에 대해 센서 신호의 선형적인 농도 의존성을 나타내었으며, 반복 실험을 행할 때 센서 신호의 재현성을 보여주었다. 따라서 본 연구에서 제조한 후 막 가스센서를 사용하여 ppb 범위의 오존 농도를 신뢰성있게 측정할 수 있음을 확인할 수 있었다.

• Toxicological Research
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• 제34권1호
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• pp.49-53
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• 2018

Cyclohexanone ($C_6H_{10}O$, CAS No. 108-94-1) is a colorless oily liquid obtained through the oxidation of cyclohexane or dehydrogenation of phenol. It is used in the manufacture of adhesives, sealant chemicals, agricultural chemicals, paint and coating additives, solvent, electrical and electronic products, paints and coatings, photographic supplies, film, photochemicals, and as an intermediate in nylon production. Owing to the lack of information on repeated inhalation toxicity of cyclohexaone, in this study, we aimed to characterize the subacute inhalation toxicity. B6C3F1 mice were exposed to 0, 50, 150, and 250 ppm of cyclohexanone for 6 hr/day, 5 days/week for 4 weeks via whole-body inhalation in accordance with the OECD Test Guideline 412 (subacute inhalation toxicity: 28-day study). Mortality, clinical signs, body weights, food consumption, hematology, serum biochemistry, organ weights, as well as gross and histopathological findings were evaluated between the control and exposure groups. No mortality or remarkable clinical signs were observed during the study. No adverse effects on body weight, food consumption, hematology, serum biochemistry, and organ weights, gross or histopathological lesions were observed in any male or female mice in any of the exposure groups, although some statistically significant changes were observed in organ weights. We concluded that no observable adverse effect level (NOAEL) is above 250 ppm in mice exposed to cyclohexanone for 6 hr/day for 5 days/week.

• Environmental Analysis Health and Toxicology
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• 제21권2호
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• pp.173-184
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• 2006

From the harmfulness expectation test conducted through a toxicity anticipation program, methylcyclohexane turned out to be harmful and simulative, but no carcinogenicity was anticipated. In a four-hour acute inhalation toxicity test, the result showed that lethal concentration ($LC_{50}$) was 3,750 ppm (15,054 mg/L), which was identified as a harmful substance on the basis of the harmful substance classification standard $2 of the Industrial safety and health law. methylcyclohexane fell under the category $4(2,500 substance from the GHS standard acute toxicity harmfulness classification. Also, from subchronic inhalation toxicity test that included 6 hours a day, five days a week, and for 13 weeks, we could observe weight, activity, long term weight, blood and blood biochemical influence from the exposure of test substance. No-observed effect level (NOEL) was determined below $100{\sim}400ppm$ inboth male and female. This material falls under the Category 2 ($50{\sim}250ppm/6hours/90days$) in the GHS (Globally Harmonized System) standard trace long-term whole body toxicity repeated exposure, and can be classified as a harmful substance in accordance with the Industrial Safety and Health Law harmful substance standard $NOEL{\leq}0.5mg/L/6hr/90day$ (rat).

• Journal of Preventive Medicine and Public Health
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• 제25권2호
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• pp.162-171
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• 1992

The hematologic effect by low-concentration and repeated exposure to mixed organic solvent remains obscure. This study was performed to evaluate the hematologic effect by mixed organic solvent exposure, especially on the type of anemia by mean corpuscular volume(MCV) and red blood cell distribution width(RDW). The subject were 64 organic solvent workers(male 4, female 60) and 78 general workers(male 18, female 60) who showed anemic tendency in worker's health examination which carried out by Pusan Paik Hospital from January to December, 1988. The author gained some hematologic findings(hemoglobin, hematocrit, RBC, WBC, MCV, MCHC, platelet count, ESR, RDW) from auto-analysis method by coulter counter S plus IV, and compared the type of anemia by MCV and RDW. In the pilot study for estimating the prevalence of anemia according to the type of b, the prevalence rate was higher in organic solvent workers than in public officials as 10.9% and 4.1% respectively. There were statistical significance in the value of hemoglobin, hematocrit, MCV, MCHC, platelet count, ESR, RDW between the two study groups with more severe anemic tendency in organic solvent workers. The type of anemia in organic solvent workers was microcytic and anisocytic with the mean value of $68.28{\pm}8.3fL$ of MCV and $19.1{\pm}4.0%$ of RDW.

• 한국산업보건학회지
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• 제17권3호
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• pp.181-191
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• 2007

With the 2-Butanethiol, which is an unidentified inhalation toxic material, acute inhalation toxicity was tested with SD rats. The $LC_{50}$ was evaluated to be 2,500 ppm (9.22 mg/L) or higher which falls under the criteria of acute toxicity Category 3 (500<$LC_{50}$<2,500 ppm) in the Industrial Safety and Health Act. In the subchronical inhalation toxicity test by 0, 25, 100, and 400 ppm, 6 hours a day, 5 days a week, for 13 weeks repeated exposure, though no death or particular clinical presentation was observed, in the female 25 and 400 ppm group, including weight change, and in each concentration group including 400 ppm, change of feed rate, eye stimulation, motility change in male group, and lesions in blood and blood biochemical were observed. In the internal organs weight, 25, 100, and 400 ppm groups in male and 400 ppm group in female showed significant (p<0.05) changes in kidney, liver, thymus, and lung. In the pathological tissue test, severe cortical tubular hyaline droplets were observed in the male 400 ppm group, and all male rats of 400 ppm group and 2 female individuals showed tubular degeneration/regeneration accompanied with pigmentation, showing that the target organs of inhalation exposure of 2-Butanethiol are spleen, kidney, nasal cavity, and adrenal. Through the tests, the NOEL of 2-Butanethiol was evaluated to be 25 ppm (0.092 mg/L) or less for both male and female.

• 한국의상디자인학회지
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• 제8권1호
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• pp.155-168
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• 2006

The purpose of this study focusing on the gather decorations shown in the modern fashion was to review needlework techniques and design features of gather decorations and thereupon, analyze the aesthetic characteristics of gather decorations shown in designers' works to examine the gather decoration trend in today's fashion. First, the decorative features of gather decorations different from the conventional costumes are shirring, lace and trimming combined or shirring repeated. Second, in view of sensualism, the gather decorations seem to play a role of enhancing the exposure as a mode of expression, while the indirect exposure or beach is mixed with the materials to widen the range of gather decoration expressions. Third, in terms of history, the conventional decorative techniques are combined with new techniques and materials to create a fantastic and romantic mood different from the conventional costumes. Fourth, in view of rhythms, the wave line of the rim for gather decorations serves to express some vivid effects; on the human body, its monotonous plane repetition will turn into a new expression or a voluminous physical sense of motion. However, since expressions or meanings of the gather decorations are much diversified, they should not be regarded as simple decoration details. Our modern designers searching for new expression of creases use unique structural forms to explore the possibility of creative gather decorations. In all, since gather decorations seem to be significant as unique details conducive to a structural pragmatism and aesthetics, it is deemed necessary to continue to develop gather decorations.

• Clinical and Experimental Reproductive Medicine
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• 제13권2호
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• pp.175-180
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• 1986

It has been reported that oral kallikrein therapy exerts a favourable effect on sperm motility in asthenozoospermic patients. In order to evaluate the efficacy of kallikrein on asthenozoospermia, a total of 20 subfertile male patients with varicocele, whose sperm counts were less than $40{\times}10^6/ml$ and sperm motility was less than 30%, was subjected to this clinical study (Table 1). They were divided into 2 study groups: 1) Varicocelectomy group consisted of 10 patients with varicocele (grade II-III) who underwent varicocelectomy. 2) Kallikrein group was composed of 10 patients with varicocele (grade I) who were given kallikrein orally 600 KU (kallikrein unit) daily divided 3 times after meal for 3 to 9 months. Semen analyses were repeated twice before the study, once a month during the study and twice after the study. Effective results designate that sperm parameters improved more than 30% from the basical levels after varicocelectomy or kallikrein exposure. Sperm counts increased from $32.5{\times}10^5/ml$ to $45.5{\times}10^6/ml$ after varicocelectomy in 3 patients and sperm motility increased from 25% to 38.5% after varicocelectomy in 3 patients. Pregnancy occurred in 2 patients of 3 responders and 1 patient of 7 non-responders 3 to 6 months after varicocelectomy in Varicocelectomy group. Sperm motility increased from 28% to 40.2% after kallikrein treatment in 3 patients. Pregnancy occurred in 2 patients of the 3 responders in Kallikrein group (Tables 2-3). There were no significant changes in volume and morphology in Varicocelectomy group before after varicocelectomy and no significant changes in volume, counts, and morphology before and after kallikrein exposure. No remarkable side effects were noted with kallikrein treatment.

• Safety and Health at Work
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• 제1권2호
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• pp.192-200
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• 2010

Objectives: We have investigated the toxic effects of the inhalation of subchronic and acute levels of n-octane. Methods: The rats were exposed to n-octane of 0, 2.34, 11.68 and 23.36 mg/L (n = 5 rats/group/gender) in an acute inhalation test (Organization for Economic Co-operation and Development (OECD) TG 403), or to 0, 0.93, 2.62 and 7.48 mg/L (n = 10 rats/group/gender) for a subchronic inhalation test (OECE TG 413), to establish a national chemical management system consistent with the Globally Harmonized Classification System (GHS). Results: Acutely-exposed rats became lethargic but recovered following discontinuation of inhalation. Other clinical symptoms such as change of body weight and autopsy finds were absent. The LC50 for the acute inhalation toxicity of n-octane was determined to exceed 23.36 mg/L and the GHS category was 'not grouping'. Subchronically-treated rats displayed no significant clinical and histopathological differences from untreated controls; also, target organs were affected hematologically, biochemically and pathologically. Therefore, the no observable adverse effect level was indicated as exceeding 7.48 mg/L and the GHS category was 'not grouping' for the specific target organ toxicity upon repeated exposure. Conclusion: However, n-octane exposure should be controlled to be below the American Conference of Industrial Hygienists recommendation (300 ppm) to prevent inhalation-related adverse health effects of workers.

• 대한불안의학회지
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• 제7권1호
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• pp.29-33
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• 2011

Objective : This study was performed to analyze the relationship between posttraumatic stress, coping style, and dissociation in Korean firefighters. Methods : Subjects included 193 male and 9 female firefighters in the metropolitan city of Daejeon. Their age ranged from 25 to 57 with an average of 39.17 (SD : 7.572) years. Their posttraumatic stress or traumatic experiences were assessed with the Korean Version of the Posttraumatic Stress Diagnostic Scale. Their coping style was categorized with the Korean version of the Ways of Coping Checklist. Their dissociation was assessed with the Korean version of Dissociative Experiences Scale. The data analysis included a correlation analysis and structural equation modeling. The modeling tested the validity of the model that posttraumatic stress had a direct effect on dissociation and coping style had an mediatory effect between stress and dissociation. Results : First, firefighters' posttraumatic stress or traumatic experiences had a direct effect on dissociation, a symptom of a mental disorder. Second, the firefighters employed passive styles to cope with their stress. This is explained that they had been exposed to their traumatic events repeatedly without being able to control it themselves. Third, coping style had no effect on the mediation between posttraumatic stress and dissociation. This is explained in terms of repeated exposure to the traumatic events. Conclusion : Based on the results, it is concluded that Korean firefighters' dissociation was not relieved by their coping effort but associated directly with their traumatic experiences. To decrease their dissociation, it is necessary to reduce the exposure to their traumatic events.

• 한국산업보건학회지
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• 제29권3호
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• pp.383-393
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• 2019

Objectives: The proportion of those working beyond 53 hours a week in 2018 has reached 16.8% of the total number of workers in the Republic of Korea (Statistics Korea, 2018). Although there are many studies that have dealt with the correlation of long working hours and increasing risk of work-related health problems, studies dealing with the factors impacting work-related health problems of workers according to their working hours are few. This study aims to ascertain factors impacting work-related health problems of workers based on their working hours through thorough research on their work environment. Methods: Necessary factors for this study were extracted from 'the 4th Korean Working Conditions Survey to analyze details on normal characteristics and work environments used for the study analysis, work hours, and health problems related to work. Results: The results are as follows: First, men showed a greater probability of exposure to work-related health problems than did women, especially in the 50s age group, which showed the highest potential for health problems from work among age groups. Second, service providers and sales professionals showed a higher probability of work-related health problems. Third, for the work environment, health problems at work related to vibration, noise, chemical and poison exposure, exhaustion, pain, standing position, and repeated motion showed a higher probability if the work hours are long. Conclusions: This study suggests that the minimization of overtime labor would prevent work-related health problems and diseases, improve the well-being of workers, and decrease the negative impact on workers in the subject area.