• Journal of Environmental Health Sciences
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• v.16 no.2
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• pp.97-103
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• 1990

For this study, I used the urine of 100 dental laboratroy technicians and 24 students in Chonbuk region. The purposes of this study were to investigate concentrations of cadmium (Cd), nickel (Ni) and chromium (Cr) in the air of dental laboratories. The results were as follows: 1. The concentrations of Cd is 0.0115mg/m$^{3}$ in the porcelain part, 0.0090mg/m$^{3}$ in the polishing part, that of Ni is 0.2864mg/m$^{3}$ in the porcelain part, 0.3188mg/m$^{3}$ in the polishing part, that of Cr is 0.0448mg/m$^{3}$ in the porcelain part, 0.1032mg/m$^{3}$ in the polishing part. 2. The concentrations of Cd, Ni and Cr in the technicians urine are 3.06 $\mu$g/l, 44.55 $\mu$g/l and 14.58 $\mu$g/l. Those of students, urine as the control group are 1.93 $\mu$g/l, 19.05 $\mu$g/l and 7.48 $\mu$g/l. There is significant difference between experimental group and control group (P < 0.01). 3. Watching for age and working place, 31-40 years age group reveals the highest group in the concentrations of Cd. Over 41 year age group represents the highest group in the concentrations of Ni and Cr (P < 0.01) The concentration of Cd turns up the highest in the partial part and that of Ni and Cr appears the highest in the polishing part (P < 0.01). Looking into working age, over 7 year group is the highest group in the concentrations of all investigated (P < 0.05).

• Journal of Environmental Health Sciences
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• v.33 no.4
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• pp.227-234
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• 2007

Recent epidemiologic studies show that gestational exposure to air pollution adversely affects pregnancy outcomes including low birth weight in preform birth. In this study, we evaluated the effect of air pollutants on LBW (low birth weight) on firstborn fetus throughout the gestational period using the birth cohort between 1999 and 2003 in Seoul. Using birth cohort data from the National Statistics Office of Korea we identified 288,346 firstborn births (excluded missing data on lack of information for birth weight and discordance between residential and certificated address from a total of 316,451) during 1999 to 2003 with complete covariate (gender, parity, date of birth, gestational age, parental age and educational level, maternal occupation etc.) and maternal residential history data. Our subjects were defined as more than 37 weeks and less than 44 weeks of completed gestation and we identified 5,457 persons (1.89%) by low birth weight (<2.5 kg) in this study. Using logistic regression, we estimated the risk of mean (entire pregnancy and trimester period) air pollution concentrations for CO, $O_3,\;PM_{10},\;NO_2\;and\;SO_2$. In terms of trimester-specific exposure, we found that some air pollutants exposure in each trimester would increase the risk for LBW. Results also showed that the effect size of air pollutants exposure during the first and third trimester is higher than during the second trimester. In all trimester, the estimated risk of LBW was 1.831 (95% CI=1.573-2.132) with unit increase for CO, 1.139 (95% CI=1.107-1.172) for 50, and 1.009 (95% CI=1.001-1.017) for $O_3$. Our results suggest that exposure during the gestation period to relatively low levels of some air pollutants may be associated with a reduction in birth weight on first-born fetus. These findings implicate the effective risk management strategies should be applied to minimize the public health impacts for pregnant women.

• Advances in pediatric surgery
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• v.16 no.2
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• pp.108-116
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• 2010

Air reduction is a safe, effective, and fast initial treatment for pediatric intussusception. There is low dose radiation exposure. Factors affecting outcomes of air reduction were analyzed by reviewing the clinical features and results of treatment. A total of 399 out of 485 patients with pediatric intussusceptions were treated at the Seoul National University Children's Hospital from 1996 to 2009. All of the patients received air reduction as the first line of treatment. Clinical features such as gender, age, seasonal variation, symptoms, signs, types, pathologic leading point, and treatment results including success rate, complication, recurrence, NPO time, and duration of hospitalization were reviewed. The Pearson chi-square, student T-, and logistic regression tests were used for statistical analysis. P-value less than 0.05 was considered to be statistically significant. The prevalent clinical features were: male (65.4 %), under one-year of age (40.3 %), ileocolic type (71.9 %), abdominal pain (85.4 %), and accompanying mesentery lymph node enlargement (2.2 %). The overall success rate for air reduction was 78.4 % (313 of 399 patients), and the perforation rate during reduction was 1.5 %. There were 23 recurrent cases over 21.6 months. All were successfully treated with re-do air reduction. Reduction failures had longer overall NPO times (27.067hrs vs. 43.0588hrs; p=0.000) and hospitalization durations (1.738d vs. 6.975d; p=0.000) compared to the successful cases. The factors affecting success rates were fever (p=0.002), abdominal distension (p=0.000), lethargy (p=0.000) and symptom duration (p=0.000) on univariate analysis. Failure rates were higher in patients with symptom durations greater than 24 hours (p=0.023), and lethargy (p=0.003) on multivariate analysis. Air reduction showed high success rates and excellent treatment outcomes as the initial treatment for pediatric intussusception in this study. Symptom duration and lethargy were significantly associated with reduced success rates.

• Tuberculosis and Respiratory Diseases
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• v.65 no.6
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• pp.457-463
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• 2008

Background: The attenuation of the lung parenchyma increases on expiration as a consequence of decreased air in the lung. Expiratory CT scans have been used to show air trapping in patients with chronic airway disease and diffuse parenchymal disease and also in asymptomatic smokers. Although there have been several reports investigating the regional air trapping on a expiratory CT scan, there have been only a few reports evaluating the changes of whole lung attenuation with considering its clinical significance, and especially in healthy subjects. The purpose of this study was to evaluate the correlation of an expiratory increase of lung attenuation with age and smoking in healthy subjects. Methods: Asymptomatic subjects who underwent a low dose chest CT scan as part of a routine check-up and who showed normal spirometry and a normal inspiratory CT scan were recruited for this study. We excluded the subjects with significant regional air trapping seen on their expiratory CT scan. Lung attenuation was measured at 24 points of both the inspiratory and expiratory CT scans, respectively, for 100 subjects. The correlations between an expiratory increase of the lung attenuation and the amount of smoking, the patient's age and the results of spirometric test were assessed. Results: There were 87 men and 13 women included in this study. Their median age was 49.0 years old (range:25~71). Sixty current smokers, 24 ex-smokers and 16 non-smokers were included. As age increased, the expiratory increase of lung attenuation was reduced at every measuring points (r=-0.297~-0.487, Pearson correlation). The statistical significance was maintained after controlling for the effect of smoking. Smoking was associated with a reduction of the expiratory increase of lung attenuation. But the significance was reduced after controlling for the patient's age. The $FEV_1$, FVC, $FEV_1/FVC$ and $FEF_{25{\sim}75%}$ were not associated with an expiratory increase of lung attenuation. Conclusion: The expiratory increase of lung attenuation in subjects with a normal inspiratory CT scan was negatively correlated with age. It was also reduced in heavy smokers. It may reflect aging and the smoking related changes.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1976.06a
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• pp.87.4-88
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• 1976

The statistcal study was done on 81 cases of the foreign bodies in the food passages (73 cases) and air passages (8 cases), who had visited the Dept. of Otolaryngology of Kyung Hee Medical Center and treated endoscopically, from Nov. 1971 to Mar 1976. The results were as follows, 1) The incidence of esophageal foreign bodies (73 cases) in order of frequency was coin (61 cases; 83.6%), bone (6 cases; 8.2%), food particles (3 cases; 4.1%), discs (2 cases), and other metals (l case). The incidence of foreign bodies in the air passages (8 cases) was food particles (3 cases; 37.5%), pointed metal (2 cases; 25%), plastic pencil cap (l case), plastic ring (1 case), and wood piece (1 case) in order. 2) In sex distribution, 51 cases (62.9%) were males and 30 cases (37.1%) were females, and the ratio between males and females was about 1.7 : 1.3. In the age incidence, 69 cases (82.5%) of all foreign bodies were under 5 years of age, and especially, coin cases were 59 cases (96.7%) and the highest was 8 years of age, lowest was 11 months of age. 7 cases (87.5%) of all airway foreign bodies were under 10 years of age. 4) The ratio between the food passages(73 cases) and the air passages (8 cases) was about 9 : 1. In the location of the foreign bodies of the food passages, 66 cases (90.4%) were in the first esophageal narrowing, 5 cases (6.9%) in the second narrowing, and 2 cases (2.7%) in the third narrowing. In the air passages, the frequent sites were trachea (5 cases; 62.5%), larynx (2 cases), and bronchus (1 case) in order. 5) In duration of lodgement, 63 cases (86. 3%) of esophageal foreign bodies were removed within 24 hours, and one case was removed within 16 days. The number of cases lodged within 24 hours were 4 cases (50%). in the air passages and one case was removed within 18 days. 6) In treatment, 37 cases (50.7%) of esophageal foreign bodies were extracted by modified upper esophagoscopy, 33 cases (42.5%) by esophagoscopy under the local anesthesia, 3 cases (4.1%) by esophagoscopy under the general anesthesia. 8 cases of the coin cases were passed into the stomach during the endoscopic examination. Laryngeal foreign bodies (2 cases; 25%) were extracted by laryngoscopy under the local anesthesia. 2 cases (40%) of tracheal foreign bodies by Bronchoscopy with tracheotomy under the local anesthesia, 3 cases (60%) by Bronchoscopy under the general anesthesia, and bronchial foreign body (1 case) by open thoracotomy under the general anesthesia, at the Dept. of Chest surgery.

• Computers and Concrete
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• v.20 no.2
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• pp.215-227
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• 2017

A finite element model (FEM) for predicting early-age behavior of reinforced concrete (RC) bridge deck slabs with fiber-reinforced polymer (FRP) bars is presented. In this model, the shrinkage profile of concrete accounted for the effect of surrounding conditions including air flow. The results of the model were verified against the experimental test results, published by the authors. The model was verified for cracking pattern, crack width and spacing, and reinforcement strains in the vicinity of the crack using different types and ratios of longitudinal reinforcement. The FEM was able to predict the experimental results within 6 to 10% error. The verified model was utilized to conduct a parametric study investigating the effect of four key parameters including reinforcement spacing, concrete cover, FRP bar type, and concrete compressive strength on the behavior of FRP-RC bridge deck slabs subjected to restrained shrinkage at early-age. It is concluded that a reinforcement ratio of 0.45% carbon FRP (CFRP) can control the early-age crack width and reinforcement strain in CFRP-RC members subjected to restrained shrinkage. Also, the results indicate that changing the bond-slippage characteristics (sand-coated and ribbed bars) or concrete cover had an insignificant effect on the early-age crack behavior of FRP-RC bridge deck slabs subjected to shrinkage. However, reducing bar spacing and concrete strength resulted in a decrease in crack width and reinforcement strain.

• Journal of Preventive Medicine and Public Health
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• v.26 no.3 s.43
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• pp.387-399
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• 1993

This study was conducted to analyze blood lipid profile and other risk factors among crew members who are currently active and had more than 10 years of experience as crew members. Data was analyzed using medical record files in an airline medical department. The results are as follows. 1. The total number of crew members studied was 392. Among age groups, those below age 40 consisted of 26(6.9% of the total), those in age $41{\sim}50$ were 135 (34.4%) and those over age 51 were 230 (58.7%). 263 were former air force pilots consisting 66.9%. Those who had captain status numbered 21 I comprising 53.7% of the total. The type of aircraft most of the crew members involved were large size aircraft which totaled 268 (68.2%). With respect to the number of working years as crew members, 488(48.9%) comprised the largest group with $11{\sim}15$ years. 2. The rate of smoking among crew members has shown gradual decrease with 50.3% smoking in 1983 to 33.6% in 1993. Among $41{\sim}50$ age group the rate has shown a decrease from 20.9% to 13.3% In those group over age 51 it decreased from 25.5% to 16.6%. But group below age 40 were within the range of 3.6~3.8% with no significant change in the rate of smoking. 3. Body Mass Index in age group over 51 was slightly higher than other age groups. On the whole, BMI over 25 was not found. 4. The total cholesterol levels of those below age 40 were $196.9{\pm}38.5mg/dl,\;216.2{\pm}39.2mg/dl$ in ages $41{\sim}50$, and $225.1{\pm}42.5mg/dl$ in age group over 51. No significant difference was found among age groups. 5. HDL-cholesterol levels of over age 50 were higher than other age group and ranged from $40{\sim}55mg/dl$. 6. LDL-cholesterol levels of those over 51 were $126.7{\pm}37.7mg/dl$ higher than other age groups. But there were no significant changes in all age during 10 years of follow up. 7. Cardiac index of age group below age 40 was 3.8, 4.3 in age group $41{\sim}50$ and 4.5 in those over age 51 group. No significant changes among groups were found during the follow up period. 8. Triglyceride levels of age group below age 40 was $142.2{\pm}70.1,\;167.3{\pm}77.5$ in age group of $41{\sim}50$ and $113.6{\pm}897$ in age group over 50 showing that triglyceride levels increased with age. No significant changes in pattern were noted.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.45-50
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• 2000

Objectives : This study was undertaken to evaluate correlation between the levels of hippuric acid in blood plasma (HAP) and those of toluene concentration in the workplace air. Methods : Study subjects were composed of two groups; 21 workers who were occupationally exposed to toluene and 25 rural-area residents who were not exposed to any known occupational toluene source, as an exposed group and a reference group, respectively. Mean age and work duration of the exposed was 42 years and five years, respectively. Mean age of the reference was 42 years. To determine toluene concentrations in the workplace air, air sampling has been conducted for more than six hours using a personal sampler, and analyzed by a gas chromatography-flame ionization detector. Concentrations of hippuric acid in biological samples were determined by a high performance liquid chromatography-ultraviolet detector. Results : Geometric mean(geometric standard deviation) of HAP and hippuric acid in urine(HAU) for the exposed was 1.39(2.21) mg/L and 2.77(1.46) g/L, respectively, which were significantly different from those of the reference [HAP, 9.45(2.94); HAU, 0.37(0.45)]. Teluene concentration in the workplace air was 86.92(range: $45.18\sim151.23$)ppm. The level of HAP or HAU was significantly correlated (r=0.70 and r=0.63, respectively) with that of toluene in the workplace air. The estimated regression equation was logHAP(mg/L)=-3.60+1.93 log(toluene, ppm) or logHAU(g/L)=-0.85+0.67 log(toluene, ppm). The magnitude of correlation was further enhanced when analyzing relationship between toluene concentrations lower than 100 ppm and its corresponding HAP levels. Conclusion : Overall, plasma hippuric acid levels were well correlated with toluene concentrations in the workplace air, and a statistically significant correlation was observed for the samples with toluene concentration lower than 100 ppm.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.201-207
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• 2005

This study was carried out to investigate the correlation between toluene in air and hippuric acid in human urine, which is based in the results of the health check-in and measure of working environment, was investigated for five years. Toluene in air and hippuric acid in urine were checked 116 workers who exposed to toluene in five type of industry. The Mean concentration of toluene in air by type of industry and every year and sex distinction, had positive correlation.(p<0.01) The Mean concentration of hippuric acid in urine by type of industry, every year, sex distinction, disparity of age and term of duty had positive correlation.(p<0.01).

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.399-404
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• 2006

Heating and cooling load of ventilation is a very important part of building energy saving. Improving ventilation effectiveness can save building energy consume and supply fresh air to indoor efficiently. So this study measured mulity-zone aiflow and ventilation effectiveness according to ventilation types. Result of measurement show that ventilation effectiveness is depends on ventilation system design rather than ventilation types.