• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.1-6
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• 2018

Also, t-cincreaseisdecreasein order In hydroponics, the accumulation of inorganic ions in the root zone are closely related to the irrigation volume. Therefore, the effects of irrigation volume on the growth and yield of tomatoes are very signigicant. This study was conducted to investigate the effect of irrigation volume on inorganic ions of root zone in hydroponic culture using coir substrate. The irrigation volume was adjusted to 4 levels depending on the integrated solar radiation for each growth period. The drainage ratio was calculated by daily amount of irrigation and drainage. The higher irrigation volume is, drainage ratio and water absorption tended to increase. But, the water absorption in the treatment of high irrigation volume was decreased in February and March compared to the treatment of medium high irrigation volume. By calculating monthly average irrigation volume and the drainage ratio, 120 to 1$40J/cm^2$ in January, 100 to $120J/cm^2$ in February, 80 to $100J/cm^2$ in March, 70 to $90J/cm^2$ in April and 60 to $75J/cm^2$ in May was detected as appropriate irrigation volume ranges which drainage ratio was 20-30%. The higher irrigation volume, the lower the concentration of ions decrease, which could prevent the accumulation of nutrients in the root zone. However, due to the characteristics of the coir substrate that absorbs ions, concentration of ions was significantly high when the drainage ratio was 20-30%. However, concentrations of P and K were sometimes lower in the drainage than that of irrigation water regardless of the treatment. Mg and S were the most highly accumulated ions even in the treatment of high irrigation volume. In low radiation season, there was no difference in the ion concentration in the drainage depending on the irrigation volume. In high radiation season, the lower irrigation volume, resulted to the higher ion concentration in the drainage. After March, it was difficult to prevent the increase of ions concetration in the drainage by only adjusting irrigation volume. Thus, it is necessary to decrease the EC of irrigation solution to prevent the accumulation of nutrients in the root zone.

• Korean Journal of Radiology
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• v.2 no.1
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• pp.28-36
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• 2001

Objective: To provide a systematic overview of the effects of various parameters on contrast enhancement within the same population, an animal experiment as well as a computer-aided simulation study was performed. Materials and Methods: In an animal experiment, single-level dynamic CT through the liver was performed at 5-second intervals just after the injection of contrast medium for 3 minutes. Combinations of three different amounts (1, 2, 3 mL/kg), concentrations (150, 200, 300 mgI/mL), and injection rates (0.5, 1, 2 mL/sec) were used. The CT number of the aorta (A), portal vein (P) and liver (L) was measured in each image, and time-attenuation curves for A, P and L were thus obtained. The degree of maximum enhancement (Imax) and time to reach peak enhancement (Tmax) of A, P and L were determined, and times to equilibrium (Teq) were analyzed. In the computed-aided simulation model, a program based on the amount, flow, and diffusion coefficient of body fluid in various compartments of the human body was designed. The input variables were the concentrations, volumes and injection rates of the contrast media used. The program generated the time-attenuation curves of A, P and L, as well as liver-to-hepatocellular carcinoma (HCC) contrast curves. On each curve, we calculated and plotted the optimal temporal window (time period above the lower threshold, which in this experiment was 10 Hounsfield units), the total area under the curve above the lower threshold, and the area within the optimal range. Results: A. Animal Experiment: At a given concentration and injection rate, an increased volume of contrast medium led to increases in Imax A, P and L. In addition, Tmax A, P, L and Teq were prolonged in parallel with increases in injection time The time-attenuation curve shifted upward and to the right. For a given volume and injection rate, an increased concentration of contrast medium increased the degree of aortic, portal and hepatic enhancement, though Tmax A, P and L remained the same. The time-attenuation curve shifted upward. For a given volume and concentration of contrast medium, changes in the injection rate had a prominent effect on aortic enhancement, and that of the portal vein and hepatic parenchyma also showed some increase, though the effect was less prominent. A increased in the rate of contrast injection led to shifting of the time enhancement curve to the left and upward. B. Computer Simulation: At a faster injection rate, there was minimal change in the degree of hepatic attenuation, though the duration of the optimal temporal window decreased. The area between 10 and 30 HU was greatest when contrast media was delivered at a rate of 2 3 mL/sec. Although the total area under the curve increased in proportion to the injection rate, most of this increase was above the upper threshould and thus the temporal window was narrow and the optimal area decreased. Conclusion: Increases in volume, concentration and injection rate all resulted in improved arterial enhancement. If cost was disregarded, increasing the injection volume was the most reliable way of obtaining good quality enhancement. The optimal way of delivering a given amount of contrast medium can be calculated using a computer-based mathematical model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3658-3666
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• 2014

The presence of $^{238}U$, $^{232}Th$ and $^{40}K$, which are naturally residing radionuclides, in the ordinary soil of Busan, the 2nd largest city in Korea, was anlayzed and the residents' radiation exposure to ordinary soil was evaluated. Regarding the measurement methods, to conduct a detailed analysis of the naturally residing radionuclides in the soil of Busan, this study divided the 16 administrative districts into a lattice structure with 3 spots, and collected a total of 48 soil samples (July 2012 and April 2013). ICP-MS was used to analyze the concentration of the radioactivity of $^{238}U$ and $^{232}Th$ in the soil, and a HpGe detector, a gamma ray detector, was used to analyze the radioactivity of $^{40}K$. The measurement values of this study were compared with the concentration of radioactivity of East Asian regions. The concentration of $^{238}U$ nuclides in Korea was lower than the mean, whereas the concentration of $^{232}Th$ and $^{40}K$ nuclides was higher than the mean. The higher mean concentrations of $^{232}Th$ and $^{40}K$ than the mean were attributed to the many granite areas that contain a great deal of naturally occurring radionuclides.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.837-842
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• 2014

A computer program is developed for the prediction of NO generation by the addition of water moisture and water electrolysis gas in LNG-fired turbulent reacting flow. This study is the first part to deal with the moisture effect on NO generation. In this study, parametric investigation has been made in order to see the reduction of thermal NO as a function of amount of moisture content in a LNG-fired flame together with the swirl and radiation effect. First of all, calculation results show that the flame separation together with the NO concentration separation are observed by the typical flow separation due to strong swirl flow. With a fixed amount of air, the increased amount of water moisture from 0 to 10% by 2% interval shows the decrease of NO concentration and flame temperature at exit are from $973^{\circ}C$ and 139 ppm to $852^{\circ}C$ and 71 ppm. The radiation effects on the generation on NO appears more dominant than swirl strength over the range employed in this study. However, for the strong swirl flow employed in this study, the flow separation cause the relatively high NO concentration observed near exit after peak concentration in the front side of the combustor.

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.149-158
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• 2012

In this paper, we measured the variations of radon concentrations in groundwater using low-level Liquid Scintillation Counter (LSC), an instrument for analyzing the alpha and beta radionuclides at its 10 sites around the Kumjung-Gu, north-western of Busan. Optimization of Pulse Shape Analyzer (PSA) to determinate the highest value of figure of merit (FM) was decided using Quantulus 1200 LSC with radium-226 source, the optimal PSA level was shown in the range of 100 to 110. The results show that the Minimum Detectable Activity (MDA) of radon concentrations is 0.61 $Bq{\cdot}L^{-1}$ for 20 minutes in PSA level. We find that the average radon concentration in groundwater is high in granitic rock area and low in volcanic rock area. (Biotite granite : 191.39 $Bq{\cdot}L^{-1}$, Micro graphic granite : 141.88 $Bq{\cdot}L^{-1}$, Adamellite : 92.94 $Bq{\cdot}L^{-1}$, Andesite (volcanic) : 35.35 $Bq{\cdot}L^{-1}$). No significant seasonal variation pattern is observed from the long-term variation analysis from 10 selected sites. We have not seen the significant correlation of radon concentration to groundwater temperature, atmospheric temperature, atmospheric pressure and rainfall. The concentration variation is probably caused by more complex factors and processes.

• Journal of Environmental Health Sciences
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• v.33 no.4
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• pp.264-275
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• 2007

The objective of this study was to offer basic and scientific data for decision-making of policy for improvement and management of radon, natural radiation gas, in Korea and to form the foundation of radon related international cooperation. Therefore, this study collected and re-analysed the articles on exposure of radon in various indoor environment in journals related environment in Korea since 1980 and estimated the annual exposure dose and effective dose by exposure of radon received by inhabitants in them. The highest pooled average radon concentration of $50.17{\pm}4.08\;Bq/m^3$ (95% CI : $42.17{\sim}58.17\;Bq/m^3$) was found in dwelling house among various indoor environment. All of pooled average radon concentration estimated in this study showed lower than the guideline concentration ($148\;Bq/m^3)$ of US EPA and the Korean Ministry of Environment. The annual effective dose received by inhabitants in various indoor environment was estimated 1.071 mSv/yr. That is equal to annual effective dose (1.0 mSv/yr) by exposure of radon estimated by UNSCEAR.

• Journal of Applied Biological Chemistry
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• v.54 no.1
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• pp.33-40
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• 2011

Ionizing radiation can be used to improve the color of green tea extract to brighter. As a result, the irradiated green tea extract can be applied easier and broader in food or cosmetic industry. To confirm the retention of the biological activities of the cosmetic products added with green tea polyphenols (PPs), the real cosmetic products including a skin lotion (PS) and an essence (PE) cream were manufactured. Irradiation also applied to the manufactured cosmetic products to see their improvement of color and changes of biological activity. The PP showed 72% of electron donating ability (EDA) at a 5 ppm concentration and the PS and PE containing 2% PP showed higher than 60%, which was similar inhibition activity to vitamin C. The inhibition of superoxide dismutase (SOD)-like activity of PP, PS, and PE were higher than 55% at a 500 ppm concentration and the inhibition of xanthine oxidase (XOase) were also higher than 65% at a 200 ppm concentration. The measurement of lipid oxidation by addition of $Cu^{2+}$ and $Fe^{2+}$ as prooxidants showed that PP and PS had higher metal chelating ability for $Fe^{2+}$ than that of PE and the ability increased by increase of polyphenol concentration isolated from green tea. The $Cu^{2+}$ chelating ability of PP and PS showed higher than 90% at a 200 ppm concentration. Therefore, it is concluded that addition of PP in manufacturing PS and PE retains its biological activities including EDA, inhibition of XOase and SOD-like activity, and metal chelating ability in the manufactured cosmetic products. In addition, irradiation of PS and PE improved color of the products containing PP brighter without any adverse changes in biological activity of the products.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.526-531
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• 2014

Thermal shock resistance property has recently been considered to be one of the most important basic properties, in the same way that the transverse-rupture property is important for sintered hard materials such as ceramics, cemented carbides, and cermets. Attempts were made to evaluate the thermal shock resistance property of 10 vol% TaC added Ti(C,N)-Ni cermets using the infrared radiation heating method. The method uses a thin circular disk that is heated by infrared rays in the central area with a constant heat flux. The technique makes it possible to evaluate the thermal shock strength (Tss) and thermal shock fracture toughness (Tsf) directly from the electric powder charge and the time of fracture, despite the fact that Tss and Tsf consist of the thermal properties of the material tested. Tsf can be measured for a specimen with an edge notch, while Tss cannot be measured for specimens without such a notch. It was thought, however, that Tsf might depend on the radius of curvature of the edge notch. Using the Tsf data, Tss was calculated using a consideration of the stress concentration. The thermal shock resistance property of 10 vol% TaC added Ti(C,N)-Ni cermet increased with increases in the content of nitrogen and Ni. As a result, it was considered that Tss could be applied to an evaluation of the thermal shock resistance of cermets.

• Transactions on Electrical and Electronic Materials
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• v.2 no.1
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• pp.1-6
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• 2001

$C_{x}F_{y}$ polymer film was deposited in rf and dc Fluorinert vapor ($C_{7}F_{16}$) plasmas. In the plasma phase, the spatial distribution of optical emission spectra and the temporal concentration of decomposed species were monitored, and kinetics of the $C_{7}F_{16}$ decomposition process was discussed. Deposition of $C_{x}F_{y}$ film has been tried on substrates of stainless steel, glass, molybdenum and silicon wafers at room temperature in the vapor pressures of 40 and 100 Pa. The films deposited in the rf plasma showed excellent electrical properties as an insulator for multi-layered interconnection of deep-submicron LSI, i.e. the low dielectric constant ∼2.0, the dielectric strength ∼2 MV/cm and the high deposition rate ∼100nm/min at 100W input power.

• Ceramist
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• v.21 no.3
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• pp.249-269
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• 2018

In conventional MALDI-TOF mass spectrometry, analyte molecules are known to be ionized by mixing with organic matrix molecules. As the organic matrix molecules are made into small fragments, they generate unreproducible mass peaks such that MALDI-TOF mass spectrometry is nearly impossible in the low mass-to-charge (m/z) range (< 1000). Additionally, the dried sample mixed with matrix were made as inhomogeneous crystal on metal plate. When the laser radiation was made on the sample crystal, the amount of generated sample ion was observed to be quite different according to the radiation point. Therefore, the quantitative analysis was very difficult even for the sample spots at the same concentration for the conventional MALDI-TOF mass spectrometry. In this work, we present laser desorption/ionization (LDI) mass spectrometry based on solid-matrices for the quantitative analysis of small molecules in the low m/z range by using MALDI-TOF mass spectrometry: (1) Carbon based nanostructures; (2) Semiconductor based nanomaterials; (3) Metal based nanostructures.