• Journal of Korean Society of Environmental Engineers
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• v.31 no.4
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• pp.278-286
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• 2009

In this study, four natural Mn oxides ($NMO_1-NMO_4$) was characterized using x-ray diffraction, scanning electron microscopy, and their removal efficiency for 1-naphthol (1-NP) in aqueous phase, using batch reactor, was investigated. The results were compared with one another and a synthetic manganese oxide, birnessite. The NMOs have a various Mn minerals including pyrolusite (${\beta}-MnO_2$), cryptomeltane (${\alpha}-MnO_2$) as well as birnessite (${\delta}-MnO_2$) depending on their sources, which results in different removal efficiencies (removals, kinetics) and reaction types (sorption or oxidative-transformation). The comparative study showed that $NMO_1$ (electrolytic Mn oxide) have a higher removal efficiency for 1-NP via oxidative-transformation compared to birnessite. The 1-NP removals by NMOs were followed by pseudo-first order reaction, and the surface area-normalized specific rate constants ($K_{surf},\;L/m^2$ min) determined were in order of $NMO_1(3.31{\times}10^{-3})$>${\delta}-MnO_2(1.48{\times}10^{-3}){\fallingdotseq}NMO_3(1.46{\times}10^{-3})$>$NMO_2(0.83{\times}10^{-3})$>$NMO_4(0.67{\times}10^{-3})$. From the solvent extraction experiments with the Mn oxide precipitates after reaction, it was observed that the oxidative-transformation rates of 1-NP were in order of $NMO_1{\fallingdotseq}{\delta}-MnO_2$>$NMO_3$>$NMO_4{\gg}NMO_2$ and the analysis of HPLC chromatogram and UV-Vis. absorption ratios ($A_{2/4}$, $A_{2/6}$) on the supernatant confirmed that the reaction products were oligomers formed by oxidative-coupling reaction. Results from this study proved that natural Mn oxide (except $NMO_2$) used in this experiment can be effectively applied for the removal of naphthols in aqueous phase, and the removal efficiencies are depending on the surface characters of the Mn oxides.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.261-267
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• 2010

In order to evaluate the distribution level of Cryptosporidium and Giardia in drinking water resources, distribution of Cryptosporidium and Giardia was studied in intake water of main water treatment facility with treatment capacity over 50,000 ton/day in Korea. 10 L samples from each study sites were collected quarterly for 2 years between Oct. '04 and Dec. '07. Cryptosporidium and Giardia were filtered and concentrated by capsule filter and centrifugation, and analyzed by immunomagnetic separation process and fluorescent assay. Cryptosporidium oocysts and Giardia cysts were detected in 7.0% and 9.3%, respectively, of a total 776 samples from 97 study sites. And mean detection number of Cryptosporidium oocysts and Giardia cysts in total 776 samples was 0.11/10 L, 0.16/10 L, detection range of Cryptosporidium oocysts and Giardia cysts was 0~7/10 L, 0~4/10 L, respectively. In seasonal distribution, Cryptosporidium was more frequent in spring as 9.2% than other season, Giardia was more frequent in winter as 14.6% than other season, but there was not shown significant seasonal characteristics. In correlation analysis with total 776 data, Cryptosporidium had significant correlation to total coliforms at the 0.05 level, but correlation value was too low as 0.07 (r=0.07). In case of Giardia, what had significant correlation at the 0.05 level was total coliforms and fecal coliforms, but correlation value was too low as 0.26, 0.27 respectively.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.12
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• pp.1304-1309
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• 2006

In this study, removal efficiencies of treatment processes with C. tracer which is similar to the characteristics of Cryptosporidium were investigated. The highest removal efficiency of C. tracer was 97.16% when the input dose of PACI(Poly aluminium chloride, $Al_2O_3$(10%)) was 10 mg/L. The higher turbidity and SS removal efficiencies were, the more C. tracer cohesion efficiency increased. Also when pH of the raw water was high, removal efficiency of C. tracer increased. As the correlationship($R^2$) between effluent turbidity after coagulation-precipitation and removal efficiency of C. tracer was 0.9506, removal efficiency of Cryptosporidium could be evaluated by effluent turbidity after coagulation-precipitation. Also the range of C. tracer removal efficiency by sand filtration was $94.00{\sim}95.83%$ and the correlationship($R^2$) between effluent turbidity after filtration and removal efficiency of C. tracer was 0.8704. Therefore, when filtration-effluent turbidity is good under the optimized coagulation condition, removal efficiencies of Cryptosporidium by coagulation-precipitation, sand rapid filtration and sand rapid filtration after coagulation-precipitation are estimated as 1.55 log(97.16%), 1.38 log(95.83%) and 2.31 log(99.51%) respectively.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.843-851
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• 2006

Although the detected amounts of those disease-causing(oo)cysts were high at each point in 2001, the detected amounts of Cryptosporidium and Giardia had decreased at low levels below 10(oo)cysts until 2004. Considered the detection results of each season, the most highly detected amounts of(oo)cysts were mostly recorded in summer and late summer(from June to September), while the site which the biggest amount was detected, was the point at Goryeung. The relation of Cryptosporidium with the water quality items was low, but the relations of Cryptosporidium and Giardia with turbidity were high($R^2$=0.4914, $R^2$=0.6176 respectively). And the detected amounts of Cryptosporidium and Giardia were relatively high, 20(oo)cysts/20L when the turbidity was more than 20 NTU. It was also found that the relation between the distribution of Cryptosporidium and Giardia was high, $R^2$=0.8432 and the density of Giardia was generally higher than that of Cryptosporidium. And Cryptosporidium and Giardia were simultaneously detected at each point. The primary sources that affected the density of those(oo)cysts were the livestock waste water and sewage.

• Journal of Nutrition and Health
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• v.55 no.2
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• pp.201-210
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• 2022

Vitamin A (Vit A) is a lipid-soluble vitamin required for diverse normal body functions, including good vision, reproduction, growth, development, and cellular differentiation. The therapeutic effects of Vit A have been demonstrated for the treatments of inflammation, low immunity, and cancer. The present review discusses the scientific evidence for establishing the 2020 Dietary Reference Intakes for Koreans (KDRI) for Vit A, issues caused by unit change of Vit A, and suggestions for the 2025 KDRI revision. Due to the changes in the standard bodyweight observed in several age groups, the 2020 KDRI had minor revisions as compared to the 2015 KDRI. In the 2015 KDRI, the Vit A unit has changed from retinol equivalent (RE) to retinol activity equivalent (RAE) and the activity of carotenoids became half with RAE compared to RE due to this unit change. Since the Vit A intake of Koreans relies heavily on plant-based carotenoids, the dietary intake of Vit A in Koreans as determined by considering the RAE was much lower than values obtained with RE. The analysis for Vit A intake by the Korean National Health and Nutrition Survey only reflects intakes of retinol and beta-carotene. Thus, it would be necessary to include the consumption of other provitamin A, such as alpha-carotene and beta-cryptoxanthin. Moreover, assessing the amounts of Vit A in foods should be customized to Korean diets since there are seasonal variations in the carotenoid concentration of plants. Moreover, other factors such as age- and sex-specific intake data and considerations of baseline micronutrient status, body mass index, and dietary patterns should be considered for developing more precise KDRI. In particular, the Vit A requirement needs to be met by consuming diverse foods, including animal foods.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.447-457
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• 2008

Laboratory tests for single plane sliding were conducted using the model rock slope to investigate the cut slope deformability and failure mechanism due to combined effect of engineering characteristics such as angle of sliding plane, water force, joint roughness and infillings. Also the possibility of prediction of slope failure through displacement monitoring was explored. The joint roughness was prepared in forms of saw-tooth type having different roughness specifications. The infillings was maintained between upper and lower roughness plane from zero to 1.2 times of the amplitude of the surface projections. Water force was expressed as the percent filling of tension crack from dry (0%) to full (100%), and constantly increased from 0% at the rate of 0.5%/min and 1%/min upto failure. Total of 50 tests were performed at sliding angles of $30^{\circ}$ and $35^{\circ}$ based on different combinations of joint roughness, infilling thickness and water force increment conditions. For smooth sliding plane, it was found that the linear type of deformability exhibited irrespective of the infilling thickness and water force conditions. For sliding planes having roughness, stepping or exponential types of deformability were predominant under condition that the infilling thickness is lower or higher than asperity height, respectively. These arise from the fact that, once the infilling thickness exceeds asperities, strength and deformability of the sliding plane is controlled by the engineering characteristics of the infilling materials. The results obtained in this study clearly show that the water force at failure was found to increase with increasing joint roughness, and to decrease with increasing filling thickness. It seems possible to estimate failure time using the inverse velocity method for sliding plane having exponential type of deformability. However, it is necessary to estimate failure time by trial and error basis to predict failure of the slope accurately.

• Journal of Chest Surgery
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• v.39 no.9 s.266
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• pp.659-667
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• 2006

Background: Experimental studies of vascular remodeling in the pulmonary arteries have been performed actively. These models required a persistent vascular insult for intimal injury induced by chronic hypoxia, monocrotaline intoxication or chronic air embolism and characterized medial hypertrophy and neointimal formation by active synthesis of the extracellular matrix protein. The purpose of this study was to determine the pattern of pulmonary vascular remodeling after obstruction of the pulmonary vein. Material and Method: Obstruction of the right pulmonary vein with a metal clip was performed in Sprague-Dawley rats $(352{\pm}18g,\;n=10)$ to cause pulmonary vascular disease. Fifteen days later, experimental studies were done and finally the both lungs and hearts were extirpated for experimental measurement. Pulmonary arterial pressure, weight ratio of right ventricle (RV) to left ventricle (LV) and ventricular septum (S) (RV/LV +S weight ratio), and pulmonary artery morphology (percent wall thickness, %WT) were evaluated and compared with normal control groups. Result: Pulmonary hypertension $(38{\pm}12mmHg\;vs\;13{\pm}4mmHg;\;p<0.05)$ and right ventricular hypertrophy (right ventricular/left ventricular and septal weight ratio, $0.52{\pm}0.07\;vs\;0.35{\pm}0.04;\;p<0.05$) with hypertrophy of the muscular layer of the pulmonary arterial wall (percent wall thickness, $22.4{\pm}6.7%\;vs\;6.7{\pm}3.4%;\;p<0.05$) were developed by 15 days after obstruction of the pulmonary vein. Conclusion: Obstruction of the pulmonary vein developed elevation of pulmonary blood pressure and medial hypertrophy of the pulmonary artery. These results are a part of the characteristic vascular remodeling. Theses results demonstrate that obstruction of the pulmonary vein can develope not only high pulmoanry blood flow of contralateral lung but also intima injury inducing vascular remodeling.

• Journal of Nutrition and Health
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• v.49 no.4
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• pp.258-268
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• 2016

Purpose: The purpose of this study was to estimate dietary vitamin A intake and examine major food sources of vitamin A in Korean adults. Methods: Using data from the 2007~2012 Korea National Health and Nutrition Examination Survey, a total of 33,069 subjects over 19-years-old were included in this study. We estimated individual daily intakes of retinol, carotenoids such as ${\alpha}$-carotene, ${\beta}$-carotene, ${\beta}$-cryptoxanthin, lutein/zeaxanthin, and lycopene, and vitamin A by linking food consumption data with the vitamin A database of commonly consumed foods. We compared individual vitamin A intakes with the reference value of Dietary Reference Intakes for Koreans. Results: Average dietary vitamin A intakes of study subjects were $864.3{\mu}g$ retinol equivalent/day ($495.7{\mu}g$ retinol activity equivalent/day) in men and $715.0{\mu}g$ retinol equivalent/day ($403.6{\mu}g$ retinol activity equivalent/day) in women. Exactly 42.9% and 70.6% of total subjects consumed less vitamin A than the Estimated Average Requirement (EAR) based on retinol equivalent and retinol activity equivalent, respectively. The major food sources of vitamin A were Korean radish leaves, carrot, red pepper, and laver, and the top 20 foods provided about 80% of total vitamin A intake. Conclusion: This study provides basic data for estimation of vitamin A intake in Korean adults. Further research will be needed to analyze the association of insufficient or excess intakes of vitamin A and health problems in the Korean population.