• 한국안전학회지
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• 제10권2호
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• pp.84-91
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• 1995

The characteristics of critical spontaneous ignition of granulated activated carbon were investigated In atmospheres of differing oxygen concentration. At the same concentration the larger vessels yielded the lower critical spontaneous ignition temperature. At the same vessel, as the concentration of oxygen was reduced, Ignition occurred later and at higher ambient temperature, and critical spontaneous ignition temperature increased. The apparent activation energy calculated from the Frank-Kamenetskii's ignition theory appeared to be the slight different value respectively and the mean apparent activation energy was 19850㎈/㏖.

• 한국산업보건학회지
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• 제17권1호
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• pp.43-52
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• 2007

This study was designed to investigate the difference of airborne lead concentration by type of lead industries and type of lead exposure and to evaluate their association with lead biomarkers of lead workers in 11 lead using industries. Total of 182 lead workers (male: 167, female: 15) from 11 lead industries were participated for this study from March, 2004 to August, 2005. Airborne lead concentration were measured by representative personal sampling of workers in each unit workplace and applied same concentration value to the workers in the same unit workplace who did not measure their airborne lead with personal air sampling. Tibia lead, blood lead, zinc protoporphyrin in whole blood, ${\delta}$-aminolevulinic acid in urine, hemoglobin and hematocrit were selected as study variables of indices of lead exposure. Information about type of lead exposure (fume or non-fume other), age, work duration, smoking & drinking habit were also collected. Significant differences were seen in the means of zinc protoporphyrin, blood lead and tibia lead in lead workers by different airborne lead concentration in workplace. While blood lead and tibia lead in lead workers were significantly higher in secondary smelting than other types of lead industries, zinc protoporphyrin, ${\delta}$-aminolevulinic acid in urine and airborne lead concentration were significantly higher in litharge manufacturing. While the mean blood lead was significantly higher in the lead workers working in fume type unit workplace than those of non-fume lead workers, the mean airborne lead concentration of fume workers was significantly lower than non-fume lead workers. In the multiple regression analysis of airborne lead concentration and the type of lead exposure on tibia lead and lead exposure indices after adjustment of related covariates, airborne lead concentration was statistically significantly associated with blood lead and tibia lead, but the type of lead exposure was only associated with blood lead. To verify the causal association of airborne lead concentration on blood lead and tibia lead, further studies are needed.

• 한국대기환경학회지
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• 제11권1호
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• pp.37-44
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• 1995

Concentration of particulate nitrate classified by formation mechanism and particle diameter in ambient air was determined from Feb. to Oct. 1993. Sampling was carried out using a two-stage Andersen air sampler at the top of a five-story building located at Kon-Kuk University in seoul. Concentration of N $H_{4}$N $O_{3}$ in TSP was measured by pyrolysis of sample filters at 160.deg.C for 1hr. concentration of N $H_{4}$N $O_{3}$ was higher in winter time compared with that in summmer time. Also, concentration of N $H_{4}$N $O_{3}$ was higher in fine particles compared with that in coarse particle. The range of N $H_{4}$N $O_{3}$ concentration was between 2.9 and 9.9.mu.g/ $m^{3}$. Weight fraction of N $H_{4}$N $O_{3}$ in total particulate nitrate was 31.1 .sim. 59.5%, and weight fraction of N $H_{4}$N $O_{3}$ in TSP was 2.1 .sim. 11.2%. Concentration of NaN $O_{3}$, which originated from sea salt, was highest in spring time and lowest in summer time,and the concentration range was between 0.1 and 0.7.mu.g/ $m^{3}$. NaN $O_{3}$/TSP ratio was very low (0.1 .sim. 0.4%) indicating that the portion of NaN $O_{3}$in TSP was negligible. Concentration of particulate nitrate originated from soil was 2.4 .sim. 2.9.mu.g/ $m^{3}$. Weight fraction of that in total particulate nitrate was 14.0 .sim. 37.1%.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.77-84
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• 2001

Measurements of local CO, $CO_2$, $O_2$, $N_2$, $C_3$H$_{8}$, NOx concentrations and flame temperature are made for partially premixed flame with and without acoustic excitation. The CO, $CO_2$, $O_2$, $N_2$, and $C$_3$H_8$ concentrations are determined by thermal conductivity detection (Gas-chromatograph) and NOx concentrations are determined by chemiluminescent detection (NOx analyser). To measure local sample concentration, sampling probe was made by quartz with inlet diameter of 0.25mm. In the case of excitation, the visual shape of the flame is changed from laminar flame to turbulent-like flame. The flame length is also reduced, and the flame width becomes broad. In the observation of emission concentration without acoustic excitation, meanwhile, the $CO_2$ and NOx concentrations peak at flame front where the mixture meets with surrounding air, and the CO concentration is increasing at maximum position of CO2 concentration and peaks at the centerline of the burner. In the case of acoustic excitation, the $CO_2$ concentration is widely occurred at nozzle of the burner and is higher relative to unexcitation. The CO concentration is much reduced, but NOx concentration is more increasing. And flame temperature is higher relative to unexcitation. These are caused by enhancing of mixing with surrounding air due to excitation. However, in the case of acoustic excitation, the total NOx concentration is reduced because of the shortened flame length which affects residence time.e.

• 대한지역사회영양학회지
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• 제8권6호
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• pp.814-821
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• 2003

The purpose of this study was to assess the maternal zinc status during pregnancy and to evaluate the relationship between the zinc concentration of maternal, umblical cord blood and placental tissue and pregnancy outcomes. Venous blood samples were drawn from 53 pregnant women just before delivery and the cord blood of their newborn babies was collected immediately after birth. In addition, placental tissues were extracted. We investigated the difference in the concentration of zinc in maternal, umbilical cord blood and placental tissue in two gestational age groups (preform delivery group [PT] and normal term delivery group [NT]) at 34.7 wk and 39.0 wk of mean gestational age, respectively). We also assessed correlations of the zinc concentration of maternal, umbilical cord blood and placental tissue. Lastly, we studied the correlations between the birth weights and the zinc concentration in the maternal, umbilical cord blood and placental tissue. The concentrations of maternal serum zinc and of umbilical cord serum zinc were significantly higher in the PT group (76.9$\pm$37.4 $\mu/dl$, 101.3$\pm$41.4 $\mu/dl$) than in those of the NT group (57.8$\pm$22.4 $\mu/dl$, 80.7$\pm$27.5 $\mu/dl$), respectively (p<0.05). The zinc concentration of the umbilical cord blood was significantly higher than that of the maternal blood in both groups (p<0.05). There was no significant correlation between the gestational age and the serum zinc concentration in the cord or the maternal serum. Our results showed that there was a negative relationship between the birth weight (r=-0.286) and the maternal serum zinc concentration. Despite there not being a significant difference, there was tendency for the highest concentrations of maternal serum zinc to be associated with the lowest birth weights. These findings support a possible relationship between the maternal zinc status and the pregnancy outcome, and suggest that zinc may play a role in the many biological processes involved in the successful outcome of a pregnancy.

• 한국환경보건학회지
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• 제45권1호
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• pp.18-29
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• 2019

Objectives: The purpose of this study was to examine the relationship between urinary bisphenol A concentration and allergic diseases in children. Methods: This study was conducted in Seoul, South Korea. We collected urine samples from 231 children from a single elementary school in June 2014. Among these, 69 children with urinary creatinine levels outside the normal range were excluded. Information on allergic diseases was obtained from the parents of the children. Urinary bisphenol A was analyzed using a liquid chromatography tandem mass spectrometer. Logistic regression analysis was used to determine if allergic disease was affected by urinary bisphenol A concentration. Results: Girls had a significantly higher concentration of urinary bisphenol A than did boys (p<0.05). Children of 10-12 years old had a significantly higher concentration of urinary bisphenol A than did children 7-9 years old (p<0.01). Concentration of urinary bisphenol A was increased from underweight to overweight (p<0.05). As the concentration of urinary bisphenol A was increased by $1{\mu}g/L$ or $1{\mu}g/g$ creatinine, the risks of lifetime symptoms of atopic dermatitis in children was 1.22 times (95% CI; 1.05-1.41) or 1.08 times (95% CI; 1.01-1.15). Conclusion: Concentration of urinary bisphenol A was associated with gender, age, body mass index, and allergic disease. Particularly, urinary bisphenol A concentration was associated with lifetime symptoms of atopic dermatitis. The findings of this study could contribute to the management of health effects among sensitive groups such as children.

• Journal of Veterinary Science
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• 제21권4호
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• pp.47.1-47.12
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• 2020

Background: Homocysteine (HCY) was evaluated in healthy and chronic enteropathic dogs, however no studies on dogs with immunosuppressant-responsive enteropathy are available. Objectives: The aim was to evaluate serum HCY concentrations and its prognostic role in dogs with immunosuppressant-responsive enteropathy compared to healthy dogs. Methods: Serum HCY concentration was statistically compared between 24 healthy dogs and 29 dogs with immunosuppressant-responsive enteropathy. Correlation analyses between serum total protein, albumin (ALB), C-reactive protein (CRP), folate and cobalamin, and serum HCY concentration were performed in immunosuppressant-responsive enteropathic dogs. Results: The associations between serum HCY concentration and clinical, histological, endoscopic scores and follow-up were evaluated. Mean serum HCY concentration was higher in immunosuppressant-responsive enteropathic dogs compared to control dogs (30.22 ± 8.67 µmol/L vs. 5.26 ± 2.78 µmol/L; p < 0.0001). No association between serum HCY concentration and total protein, ALB, CRP, folate concentration as well as, clinical score, histological and endoscopic scores was found. A negative correlation between serum HCY concentration and cobalamin was noted (p = 0.0025, r = -0.54). No significant difference in HCY was found between responsive and non-responsive dogs or between survivors and non-survivors. Conclusions: Although, serum HCY concentration was higher in immunosuppressant-responsive enteropathy, its prognostic value remains unclear. However, further prospective, large-scale studies are warranted to better investigate the possible prognostic role of HCY in immunosuppressant-responsive enteropathic dogs.

• 대기
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• 제34권2호
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• pp.187-202
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• 2024

We analyzed the observed characteristics of monoterpene and developed an empirical formula for monoterpene concentration in the pine-dominated mixed forest of the National Center for Forest Therapy. Monoterpene was measured at 0800, 1200 and 1700 LST once a month using sorbent tube sampling coupled with thermal desorption gas chromatography and mass spectrometry. Monoterpene concentration is low in winter and shows a maximum in June and July. The major components of monoterpene are alpha-pinene, camphene and beta-pinene. During the warm period from May to November, monoterpene concentration is higher at 0800 and 1700 LST than at 1200 LST. The empirical formula takes into account the vegetation variables, temperature-controlled emission, oxidation processes and dilution by wind. The vegetation variable accounts for the difference in observed monoterpene concentration between two sites. The observed monoterpene concentration normalized by the vegetation variable increases exponentially with air temperature. The oxidation process explains the lower monoterpene concentration at 1200 LST than at 0800 and 1700 LST during the warm period. The monoterpene estimates using the empirical formula shows a correlation of 0.52 with the observation for the development period (2018~2020), while it shows a correlation of 0.72 for the validation year (2021). Such higher correlation for the validation year than for the development period is due to the fact that variability of monoterpene concentration is better explained by air temperature in 2021 than in the development period. However, the developed formula underestimates the monoterpene concentration in May and June, showing the limitation in accurately capturing the monthly variation of monoterpene.

• 대한의생명과학회지
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• 제30권1호
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• pp.24-31
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• 2024

Mercury is a chemical pollutant widely present in the environment. Humans are generally exposed to mercury in the form of organic Hg (methylmercury) through the consumption of seafood. Koreans enjoy eating fish therefore blood mercury concentration is usually higher than in developed countries. By investigating blood mercury concentration according to the frequency of seafood consumption and sociodemographic factors, we aimed to identify recent trends in blood mercury concentration in Korean adults. This study was conducted using KoNEHS cycle 4 (2018~2020) from the National Institute Environmental Research Survey. The geometric mean concentration of blood mercury of the subjects was 2.959 (±1.018) ㎍/L, which was significantly higher in men than in women. It was observed that as the frequency of fish and shellfish consumption increased, the blood mercury concentration increased. In adjusted logistic regression, fish consumption was associated with 36.7% increased risk of blood mercury levels [Odds ratio, 1.367; 95% confidence interval (CI), 1.246~1.500], and shellfish consumption was associated with 26.5% increased risk of blood mercury levels [Odds ratio, 1.265; 95% confidence interval (CI), 1.134~1.410]. Blood mercury concentration was also found to increase as the socioeconomic level increased. In conclusion, the geometric mean concentration of blood mercury was increased compared to the one in the 3rd KoNEHS (2015~2017) and seafood consumption and socioeconomic level were still significantly associated with increasing blood mercury concentration in Korea. Therefore, it is necessary to encourage healthy seafood consumption habits and conduct continuous monitoring considering various factors to reduce blood mercury levels.

• 대한치과기공학회지
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• 제10권1호
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• pp.11-24
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• 1988

The purpose of this study was to determine the concentration of cadmium, nickel and chromium in the air of the work-place, blood of and urine of workers and compare the level of those heavy metals by the duration of work, work-place, process of work, smoking and other factors. In this study, 48 male dental laboratory technicans and 72 office workers as the control group were subjected. The concentration of cadmium, nickel and chromium in their blood sand urine, and that of heavy metals in the air of their work-rooms were examined and analyzed from June I 1987 to September 30, 1987. The results were as follows : 1. The concentration of cadmium in the air was the highest in the porcelain part, $0.0087{\pm}0.0016mg/m^3$, that of nickel was the highest in the crown bridge part, $0.4253{\pm}0.0052mg/m^3$, and that of chrnmium was highest in the partial denture part, $0.1063{\pm}0.0024mg/m^3$. 2. cadmium, nickel and chromium concentrations in the blood and urine of dental laboratory techincians were higher that in the office workers'. Especially the concentration of cadmium in the blood($1.92{\pm}1.23{\mu}g$/100ml) of th dental laboratory techician was about two times as high as that in the office workers'($0.90{\pm}0.73{\mu}g$/100ml), and the concentration of nickel in the urine($48.53{\pm}38.83{\mu}g$/e) of the dental laboratory thchnician was about two times as high as that in the office worker's($20.24{\pm}15.35{\mu}g$/e). 3. there was no difference in the concentration of cadmium, nickel and chromium in the blood and urine with a longer duration of work. 4. The concentration of cadmium and chromium in the blood and urine differed significantly depending upon the place of work. The concentration of cadmium was the highest in the blood of dental laboratory technicians working kin the poreclain part marking at $2.53{\pm}1.08{\mu}g$/100ml. The chromium level was the heighest in the blood of partial denture park workers with a concentration of $3.60{\pm}1.02{\mu}g$/100ml. Concerning the level of cadmium in urine, it was the highest in the porcelain part workers with a concentration of $3.41{\pm}3.15{\mu}g$/e. 5. The concentration of cadmium in the urine of metal trimming and polishing group($2.64{\pm}2.41{\mu}g$/e) was higher than that of non-metal trimming and polishing group($1.39{\pm}1.18{\mu}g$/e). 6. The concentration of chromium in the blood of smoking group($2.46{\pm}1.54{\mu}g$/100ml)was higher than that lf non-smoking group($1.54{\pm}1.25{\mu}g$/100ml). 7. The height positive correlation coefficient was shown between the concentration of nickel and chromium in the blood among the all correlations between 3metals(Cd, Ni, Cr) in the blood and those in urine. The correlation coefficient was relatively high(r=0.605,,p<0.01). In general, the higher the concentration of heavy metals in the air of work places the higher the concention lf them in the blood and urine of workers, mere attention should be paid to the working environment of dental laboratory workers, Furthermore, continuous biological monitoring and further research are required for an efficient health management for dental laboratory workers.