• Journal of Environmental Science International
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• v.28 no.1
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• pp.7-18
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• 2019

This study aimed to assess the impact of livestock excreta discharged from an Intensive Livestock Farming Area (ILFA) on river water quality during a rainfall event. The Bangcho River, which is one of the 7 tributaries in the Cheongmi River watershed, was the study site. The Cheongmi River watershed is the second largest area for livestock excreta discharge in Korea. Our results clearly showed that, during the rainfall event, the water quality of the Bangcho River was severely deteriorated due to the COD, $NH_4-N$, T-N, $PO_4-P$, T-P, and heavy metals (Cu, Zn, and Mn) in the run-off from nearby farmlands, where the soil comprised composted manure and unmanaged livestock excreta. In addition, stable isotope analysis revealed that most of nitrogen ($NH_4-N$ and $NO_3-N$) in the run-off was from the ammonium and nitrate in the livestock excreta. The values of ${\delta}^{15}N_{NH4}$ and ${\delta}^{15}N_{NO3}$ for the Bangcho River water sample, which was obtained from the downstream of mixing zone for run-off water, were lower than those for the run-off water. This indicates that there were other nitrogen sources upstream river in the river. It was assumed from ${\delta}^{15}N_{NH4}$ and ${\delta}^{15}N_{NO3}$ stable isotope analyses that these other nitrogen sources were naturally occurring soil nitrogen, nitrogen from chemical fertilizers, sewage, and livestock excreta. Therefore, the use of physicochemical characteristics and nitrogen stable isotopes in the water quality impact assessment enabled more effective analysis of nitrogen pollution from an ILFA during rainfall events.

• Journal of Food Hygiene and Safety
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• v.24 no.3
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• pp.211-216
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• 2009

In order to cope with risk issues of overseas on 4,4'-diaminodiphenylmethane (4,4'-MDA) known to used in the production of polyamide resins, we investigated on 4,4'-MDA migration from plastic cooking utensils. 93 samples of plastic cooking utensils were collected from the retail markets in 7 major cities of Korea during March to June, 2007 and 4,4'-MDA levels migrated to food simulants, water, 4% acetic acid, 20% ethanol and n-heptane, on plastic cooking utensils was quantified by liquid chromatography with tandem mass spectrometry (LC-MS/MS). 4,4'-MDA was detected in 14 samples, and the levels of 4,4'-MDA migrated to food simulants were in the range of $0.001{\sim}0.026$ ppm. Among them, the 4,4'-MDA migration amounts of 2 samples were above 0.01 ppm defined by the EU.

• The Journal of the Petrological Society of Korea
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• v.8 no.2
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• pp.57-70
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• 1999

The volcanic rocks of Ulleungdo reveal very high alkali element abundances and most of them have high K20/Na20 ratios and belong to potassium-series. Ulleungdo volcanics show very wide range of variation in their composition from basalts to trachytic basalt, basaltic trachyandesite, trachyandesite, and finally to trachyte on total alkali-silica diagram. Such a general trend of compositional variation can be explained well by differentiation due to fractional crystallization of various minerals. Olivine, clinopyroxene, plagioclase, ilmenite, and apatite are suggested as the major fractionated minerals. Ulleungdo volcanics show Nb/U and PbICe ratios similar to oceanic volcanics such as MORB and OIB, but significantly different .from volcanic rocks of island arc environments, which suggest that they are not directly related with subduction along the Japanese arc. LREE abundances of Ulleungdo volcanics are highly enriched compared with HREE abundances ((La)N=193-420, (L~)~=7.5-19.5).O nly trachyte-1 show appreciable negative Eu anomalies among various rock types, which suggests significant amount of plagioclase were fractionated. However, trachyte-2, trachyte-3, phonolite, and pumice reveal quite different variation trend of trace and rare earth element abundances from trachyte-1, which suggest that they have originated from different magma batches and have experienced different differentiation processes. A prominent bimodal distribution, thus lacking of intermediate composition, is observed from the Ulleundo volcanics.

• The Korean Journal of Mycology
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• v.25 no.4 s.83
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• pp.330-339
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• 1997

Botrytis cinerea T91-1 has shown to produce at least four different polygalacturonases in a liquid medium containing citrus pectin as a carbon source. One of the enzymes, its molecular weight was estimated as 37 kDa by denatured polyacrylamide gel electrophoresis, was purified by a series of procedures including acetone precipitation, ion exchange, heparin affinity, and reverse phase column chromatographies. By viscometric analysis, the enzyme was revealed as an endo-polygalacturonase. The enzyme activity was inhibited by divalent cations such as $Ca^{2+}$, $Co^{2+}$, and $Cu^{2+}$. Km and Vmax for polygalacturonic acid hydrolysis were 0.33 mg/ml and 28.6 nM/min, respectively. The optimum temperature for enzymatic activity was $55^{\circ}C$ and the enzyme showed optimal pH values between 4.0 and 4.5. The enzyme was stable up to 12 hours in the range of pH 4 to 7 and at the temperature below $30^{\circ}C$. Amino acid sequence from N-terminal up to 6 amino acids determined by Edman degradation showed little homology with polygalacturonases from fungi and plants.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.3
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• pp.225-232
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• 1998

In order to monitor the degree of heavy metal distribution in upland cultivations in Korea, both the cultivated soils and crops were collected from the 854 and 140 sites, respectively. The contents of cadmium (Cd), copper(Cu), lead(Pb), and zinc(Zn) in each sample were measured by Inductively Coupled Plasma(ICP) technique after 1N-HCl extraction. The content of Arsenic(As) was also measured with the same technique after 1N-HCl extraction. The average contents of heavy metal in surface soils(0~15 cm depth) were $0.135mg\;kg^{-1}$ for Cd, $2.77mg\;kg^{-1}$ for Cu, $3.47mg\;kg^{-1}$ for Pb, $10.7mg\;kg^{-1}$ for Zn, and $0.57mg\;kg^{-1}$ for As. Heavy metal contents of soil were similar to those values measured for upland soils in 1989, lower than soils under plastic film house in 1996. However, these contents were lower than "Countermeasure values for soil contamination"(Cd: 4, Cu: 125, Pb: 300, and As: $15mg\;kg^{-1}$ in soil) describled in Soil Environmental Conservation Act in Korea(1996). The contents of heavy metal in fresh vegetable, and root and tuber crops ranged $0.005{\sim}0.019mg\;kg^{-1}$ for Cd, $0.20{\sim}1.03mg\;kg^{-1}$ for Cu, $0.042{\sim}0.104mg\;kg^{-1}$ for Pb, and $2.0{\sim}4.0mg\;kg^{-1}$ for Zn, respectively.

• Journal of Food Hygiene and Safety
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• v.15 no.2
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• pp.95-100
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• 2000

The effect of natural foods, utilizing the extracts or juices of teas(Green tea; Camellia sinesis, Du'chung; Eucommia ulmoides Oliver), medicinal plants(Eu sung cho; Houttuynia cordata Thunb, Sam back cho; Saurus Chinensis, Baek hwa sa seal cho; Oldenladia diffusa Roxb.) seaweeds(Laver; Porphyra tenera, Sea mustard; Undaria pinnatifida, Sea staghorn; Condium fragile) and vegetables(Sweet pepper; Capsicum annuum var. angulosum, Kale; Brassia oleracea var.. acephala, Cucumber; Cucumis sativus, Onion; Allium cepa) and fruits(Tomato; Lycopericon esculentum, Maesil; Prunus mume, Plum; Prunus saticina and Grape; Vitis spp.)on the inhibition of N-Nitrosodimethylamine(NDMA) formation was investigated from the various conditions. The inhibition effect was observed in vitro using the reaction fluids of pH 1.2, 4.2 and 6.0. From the teas and medicinal plants, there was a positive response of NDMA formation; however, From the seaweed extracts, there was a negative response of the inhibition effect of NDMA formation, and as the pH of reaction fluids and the amount of materials increase, the inhibition of NDMA formation was strengthened. The inhibition ratios by the level of pH are as follows: under pH 1.2 vegetable juice were 57.6∼99.7% and fruits were 35.9∼99.7%; under pH 4.2 vegetable juice were 55.0∼97.5% and fruits were 21.3∼96.8%. All of the materials observed has been proved and shown the inhibition effect of NDMA formation.

• Tuberculosis and Respiratory Diseases
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• v.65 no.2
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• pp.91-98
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• 2008

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common organism associated with nosocomial infections. MRSA infections are becoming increasing important because they have emerged no only as healthcare-associated (HA) infections but also as community-associated (CA) ones. This study examined the moleculo-epidemiology of MRSA, which was isolated from nasal swabs in the intensive care unit (ICU) at Konyang University Hospital. MRSA are classified into HA-MRSA and CA-MRSA. Methods: From June to September 2006, 353 patients who were admitted to the ICU in Konyang University Hospital were enrolled in this study. Single nasal swabs were obtained for culture in the ICU on the 1st day. Pulsed-field gel electrophoresis and the antimicrobial resistant patterns were analyzed between HA- and CA-MRSA. An antimicrobial sensitivity test was also performed. Results: Forty two strains of MRSA were isolated from 353 patients (11.9%). Among the 42 isolates, HA-MRSA and CA-MRSA were found in 33 (78.6%), and 9 (21.4%), respectively. Eleven different PFGE types (type A to K) were identified. Types A (n=9) and B (n=7) were the most common for HA-MRSA, and types A (n=2) and B (n=2) were identified in CA-MRSA. The proportion of types A and B in CA-MRSA (44.4%) was similar to that in HA-MRSA (48.5%). The rates of resistance rates to erythromycin and ciprofloxacin were higher in HA-MRSA than in CA-MRSA. Conclusion: The rate of isolation of MRSA in an ICU setting was 11.9%. HA-MRSA was isolated more frequently than CA-MRSA. The rate of resistance of HA-MRSA to erythromycin and ciprofloxacin was higher than that of CA-MRSA. Despite the small number of subjects, the main isolates (type A and B) of CA-MRSA were similar to those of HA-MRSA.

• Journal of Chest Surgery
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• v.36 no.2
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• pp.91-97
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• 2003

With the advent of stage-adapted multimodal regiments for esophageal malignancy, accurate staging has become of utmost importance. Endoscopic ultrasono graphy(EUS) i.: a diagnostic method for the local staging of esophageal cancer, in particular for T and N evaluation. The aim of this study was to examine the diagnostic efficacy of the EUS and to evaluate the relation between prognosis and EUS findings. Material and Method : We reexamined the cases of 88 consecuitive patients who underwent transthroacic esophagectomy and cervical esophagogastrostomy for esophageal cancer from January 1991 to July 2001 We compared EUS findings, histological results and outcomes. Result : There were 83 male(94.3%) and 5 female. Median age was 61.3 years old. Overall staging accuracy were 59.0% for T staging and 76.0% for N staging, In early T staging group, the accuracy was 74.9% except 74 stage. However significant differences were not found in the ability of EUS-determined T-stage and N-Stage to predict survival. Multivariate analysis showed EUS-stage to predict survival. Conclusion : EUS provides a high degree of accuracy in assessing both T and N parameters in staging esophagal cancer. EUS should be performed in all patients with esophageal cancer, not only for staging before therapy, but also as a valuable method of determining prognosis.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.229-233
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• 2015

Currently, the majority of commercial white LEDs are phosphor converted LEDs made of a blue-emitting chip and YAG yellow phosphor dispersed in organic silicone. However, silicone in high-power devices results in long-term performance problems such as reacting with water, color transition, and shrinkage by heat. Additionally, yellow phosphor is not applicable to warm white LEDs that require a low CCT and high CRI. To solve these problems, mixing of green phosphor, red phosphor and glass, which are stable in high temperatures, is common a production method for high-power warm white LEDs. In this study, we fabricated conversion lenses with LUAG green phosphor, SCASN red phosphor and low-softening point glass for high-power warm white LEDs. Conversion lenses can be well controlled through the phosphor content and heat treatment temperature. Therefore, when the green phosphor content was increased, the CRI and luminance efficiency gradually intensified. Moreover, using high heat treatment temperatures, the fabricated conversion lenses had a high CRI and low luminance efficiency. Thus, the fabricated conversion lenses with green and red phosphor below 90 wt% and 10 wt% with a sintering temperature of $500^{\circ}C$ had the best optical properties. The measured values for the CCT, CRI and luminance efficiency were 3200 K, 80, and 85 lm/w.

• Journal of The Korean Astronomical Society
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• v.36 no.1
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• pp.43-48
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• 2003

We introduce and describe performance of the 6-meter telescope of Seoul Radio Astronomy Observatory (SRAO). All the softwares and instruments except the antenna structure and its driving system are developed for ourselves. The SIS mixer type receiver resulted in the receiver noise temperature less than 50 K (DSB) over the whole 3-mm radio window. An autocorrelation spectrometer, developed first in Korea, provides maximum 50 MHz band width over 1024 channels. Antenna surface is measured and adjusted using template method and radio holography which resulted in a superb surface accuracy bet-ter than 30${\mu}m$. Accordingly, the aperture and beam efficiences amount to $70\%$ and $75\%$, respectively, largely independent of frequency in the 85 - 115 GHz range. It is also found that telescope pointing errors are less than 10" in both azimuth and elevation and that antenna gain is almost constant against elevation greater than $20^{\circ}$, without adjusting sub-reflector position. The SRAO 6-meter telescope is now fully operational and all these characteristics verify that observations are carried out with high precision and fidelity.