• Elastomers and Composites
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• 제50권3호
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• pp.223-230
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• 2015

Bacterial infection is one of the most common and universal cause of disease spreading associated with medical and surgical environment. Antimicrobial function of plasticized polyvinyl chloride (PVC) will be useful for making hygienic environments. Here, we synthesized the PVC composite by the addition of inorganic bacteriocide containing silver, zinc and zeolite. And we investigated the growth inhibition rate for Staphylococcus aureus and Klebsiella pneumoniae which were analyzed in the presence of PVC composite with different doses of inorganic bacteriocide (1~15 wt%). Bacterial proliferation was significantly inhibited by 3 wt% of inorganic bacteriocide containing PVC composite. And we found the inhibition of bacterial biofilm formation by 5 wt% of inorganic bacteriocide containing PVC composite by the observation of scanning electron microscopy (SEM). Our data suggested that the antimicrobial effect of inorganic bacteriocide was caused by disturbing the bacterial biofilm formation.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.776-780
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• 2017

To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a $^{99m}Tc$ gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

• 한국식생활문화학회지
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• 제29권2호
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• pp.212-221
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• 2014

Korean style DASH (Dietary Approaches to Stop Hypertension) and a dietary education program for sodium reduction were developed. Reduced sodium diets (15 and 30% reductions) were developed from general diets for 3 consecutive weeks from Monday through Saturday. Subjects (19 total) were classified into two groups according to dietary education. Experimental period was from June 24 to July 23, 2012. Total sum of adaptation scores for low sodium diets significantly increased in the group that underwent dietary education compared to that without (p<0.05). After the experiment, both groups showed significantly increased values in terms of food group balance, sodium-related nutrition knowledge, attitude, and practice by paired t-test. Especially, group that underwent dietary education showed significantly higher values for attitudes by ANCOVA pre-test as a variation (p<0.01). For the results of the nutrient intake survey, group that underwent dietary education showed significantly increased values for dietary fiber (p<0.01), vitamin A (p<0.001), vitamin K (p<0.001), vitamin C (p<0.01), Folic acid (p<0.001), vitamin B12 (p<0.01), calcium (p<0.01), iron (p<0.05), and zinc (p<0.05) and significantly decreased values for sodium (p<0.05) and chloride (p<0.005). Subjects adapted to reduced sodium diets showed apparent improvements in sodium-related knowledge, attitude, practice and intake of nutrient, and these improvements were even higher in the group that underwent dietary education compared to that without. Thus, adaptation to low sodium diet combined with dietary education can improve dietary habits.

• 한국환경보건학회지
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• 제15권1호
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• pp.33-49
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• 1989

Pollution in the rivers has received considerable attention in recent years, particullary with reference to the effect due to increasing concentration of heavy metals. The metals are toxic to the ecosystem as a whole and to man in particular, since he is at the end of a variety of food chains by virture of his varigated diet. In addition, numerous laboratory tests have established that certain metals, such as Cd, pose a threat to a wide variety of aquatic organisms at concentrations as low as a few $\mu$g/1. Before the biological effects of heavy metals in impacted ecosystems can be completely assessed, however it is necessary to provide data on the concentration of heavy metals in such systems. This study was performed to investigate the concentration level of heavy metals in water, fish and sediments from upstream ($S_1-S_4$) to downstream ($S_5-S_9$) of the Mankyung river. Samples of water, fish, and sediments were collected along the tributaries of the Mankyung from September to October in 1987 and analyzed for lead, cadmium, copper, and zinc by atomic absorption spectrophotometer. From the data presented in this study, we can infer that the concentrations of the heavy metals investigated both in water and sediments are similar to those found in literature for unpolluted regions. The results obtained from the analysis of the edible tissue of the C. auratus show low concentration levels of the four heavy metals investigated. We conclude that the area is still relatively unpolluted and recommended continuing the monitoring of heavy metal concentrations to improve our understanding of their cycle in the river environment.

• 대한지역사회영양학회지
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• 제19권2호
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• pp.176-186
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• 2014

Objectives: Epidemiological studies have suggested that a higher consumption of whole grain foods can significantly reduce the risk of chronic diseases including cardiovascular diseases, type 2 diabetes and obesity. The objective of the current study was to examine associations among the consumption of whole grains and nutrient intakes and biochemical indicators associated with chronic diseases among generally healthy middle-aged Korean women. Methods: Using 24-hour recall data from the 2008-2009 National Health and Nutrition Examination Surveys, whole grain intake (g/day) was calculated for a total of generally healthy 1,953 subjects. The subjects were divided into three groups by the level of whole grain consumption (0 g/day, > 0 and < 20 g/day or ${\geq}20g/day$). Mean values or proportions of various nutrient intakes and metabolic risk factors were compared according to the level of whole grain consumption. All statistical analysis was conducted using SAS software version 9.2. Results: We observed that the overall consumption of whole grains was quite low. Specifically, 58.2% of subjects reported no whole grain consumption on the day of the survey, and the mean whole grain intake was only 15.3 g/day. The whole grain consumption was positively associated with intakes of various macro and micronutrients, namely, plant proteins and fats, dietary fiber, calcium, plant iron, potassium, zinc, vitamin A, ${\beta}$-carotene, thiamin, riboflavin, niacin, vitamin $B_6$ and folic acid. In addition, we found significantly decreasing trends in abdominal obesity and hypertriglyceridemia as whole grain intake levels increase. Conclusions: The study findings suggested the importance of promoting whole grain consumption as an efficient tool for improving various dietary aspects and preventing chronic diseases.

• 조명전기설비학회논문지
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• 제15권3호
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• pp.67-73
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• 2001

본 논문에서는 ZnO 피뢰기 소자에 대한 내구성 평가와 열화실험을 위한 저항분 누설전류 검출장치의 개발과 열화진단기법에 대하여 기술하였다. 저항분 누설전류는 ZnO 피뢰기 소자가 정상상태인지 불안정상태인지에 대한 판단의 지표로서 사용할 수 있다. 본 논문에서는 보상회로로 구성된 저항분 누설전류 측정시스템을 설계하여 구성하고, 실증실험으로서 ZnO 소자에 대한 저항분 누설전류의 측정과 고속프리에 변환기법(Fast Fourier transform)을 통해 저항분 누설전류의 주파수특성을 조사·분석하였다. 분석결과 제안한 저항분 누설전류의 측정 시스템은 실험실에서 산화아연 바리스터의 전기적·물성적 특성을 연구하고, 전력계통에 있어서 ZnO 피뢰기의 열화의 진단과 예측기술을 개발하는데 유용하게 활용할 수 있다.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.122-132
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• 1993

The aim of this study was to investigate the level of radiopacity of glass ionomer cements and to determine the optimum level of radiopacity that is the most compatible with the radiographic diagnosis of secondary caries. The experiments were performed in two parts. In the first part, the radiopacities of 9 glass ionomer cements (FI, FII, FI-LC, FII-LC, SI, SII, Vit, B-VLC, AC) and base materials(Ultra-Blend, Zinc phoaphate cements, Cavitec, Dycal) were measured by densitometer. Then all experimental materials were divided into 5 groups based on the level of radiopacity of enamel and dentin. In the second part, class III cavities with or without secondary caries were prepared in extracted anterior teeth. The representative materials of each group with different radiopacities were inserted into each cavity. The radiographs were interpreted by 15 dentists and seconsary caries were diagnosed according to a five-point confidence rating. Sensitivity and ROC analysis were used to compare observer performance. The following results were obtained : 1. The radipacity of glass ionomer cements varied between 1.111mm Al and 6.011mm Al equivalent. 2. Among experimental materials, three materials in group I had lower radiopacity than that of dentin. The radiopacity of two materials in group II slightly exeeded that of dentin. Three materials in group III had slightly lower radiopacity than that on enamel. The radiopacity of one material in group W was slightly higher than that of enamel. Four materals in group V had the radiopacity that exeeded over 2.0mm AI equivalent to that of enamel. 3. The group IV was the highest for sensitivity and the group V was the highest for ROC area. However, no significant differences were obtained among group II, III, IV and V (P<0.05) but only group I was significantly lower(P<0.01). 4. In comparison with the observer performance for the radiographic diagnosis of secondary caries, the group II, III, IV, and V were superior to the group I (P<0.01). And so the optimum level of radiopacity to detect the secondary caries was the radiopacity that is higher than that of dentin.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권1호
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• pp.1-7
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• 2014

When processing the biomass by Hydrothermal carbonization (HTC), a slow pyrolysis process, it produces bio-gas, biooil, and biochar. Among these end products, biochar is known for isolating or storing carbon and being used as a soil amendment. In this study, the characteristics of biochar generated by HTC at $250^{\circ}C$ for 1 hour, 2 hours, 3 hours, and 20 hours with synthetic food wastes and wood wastes were analyzed for potential uses in soil contaminated with heavy metals. The yield of biochar (weight %) increased when the ratio of wood wastes increased and showed a decreasing tendency as reaction time increased. Elemental analysis of biochar based on various conditions showed a maximum of 70% carbon (C) content. The carbon content showed an increasing tendency with the increase of wood wastes. Iodine adsorption test was peformed to determine the optimum reaction condition, which was 15% wood waste for mixing ratio and 2 hours for reaction time. Using biochar generated at the optimum condition, its capability of adsorbing heavy metals (Cd, Cu, Pb, Zn, Ni) was evaluated. It was concluded that lead (Pb) was removed efficiently while zinc (Zn) and nickel (Ni) were hardly adsorbed by biochar.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.131-131
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• 2010

We compared the electrical, optical, structural, and interface properties of indium zinc oxide (IZO)-Ag-IZO and IZO-Au-IZO multilayer electrodes deposited by linear facing target sputtering system at room temperature for organic photovoltaics. The IZO-Ag-IZO and IZO-Au-IZO multilayer electrodes show a significant reduction in their sheet resistance (4.15 and 5.49 Ohm/square) and resistivity ($3.9{\times}10^{-5}$ and $5.5{\times}10^{-5}$Ohm-cm) with increasing thickness of the Ag and Au layers, respectively. In spite of its similar electrical properties, the optical transmittance of the IZO-Ag-IZO electrode is much higher than that of the IZO-Au-IZO electrode, due to the more effective antireflection effect of Ag than Au in the visible region. In addition, the Auger electron spectroscopy depth profile results for the IZO/Ag/IZO and IZO/Au/IZO multilayer electrodes showed no interfacial reaction between the IZO layer and Ag or Au layer, due to the low preparation temperature. To investigate in detail the Ag and Au structures on the bottom IZO electrode with increasing thickness, a synchrotron x-ray scattering examination was employed. Moreover, the OSC fabricated on the IZO-Ag-IZO electrode shows a higher power conversion efficiency (3.05%) than the OSC prepared on the IZO-Au-IZO electrode (2.66%), due to its high optical transmittance in the wavelength range of 400-600 nm, which is the absorption wavelength of the P3HT:PCBM active layer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.101-101
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• 2010

ZnO shows a direct band gap of 3.37eV, large exciton binding energy (~60 meV), high oxidation ability, high sensitivity to many gases, and low cost, and it has been used in various applications such as transparent electrodes, light emitting diodes (LEDs), gas sensors and photocatalysts. Among these applications ZnO as photocatalyst has considerably attracted attention over the past few years because of its high activities in removing organic contaminants generated from industrial activities. In this research, ZnO nanoparticles were synthesized by spray-pyrolysis method using the zinc acetate dihydrate as starting material at synthesis temperature of $900^{\circ}C$ with concentration varied from 0.01 to 1.0M. The physical and chemical properties of the synthesized ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increased precursor concentration, a primary, secondary particle sizes of ZnO nanoparticles increased by 0.8 to $1.5{\mu}m$ and 15 to 35nm, and their crystallinity was improved. Methyleneblue (MB) solution ($1{\mu}M$) as a test comtaminant was prepared for evaluating the photocatalytic activities of ZnO nanoparticles synthesized in different precursor concentration. The results show that the photocatalytic efficiency of ZnO nanoparticles was gradually enhanced by increased precursor concentration.