• Journal of the Korean GEO-environmental Society
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• v.18 no.10
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• pp.23-34
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• 2017

As the electrical property of fully saturated soils is dependent on the pore water, it has been commonly used for the detection of the contamination into the ground. The objective of this study is to investigate the electrical characteristics according to the salinity and the lead concentration in fully saturated soils. Fresh water and saline water with the salinity of 1%, 2% and 3%, which are mixed with 6 different lead solutions with the range of 0~10 mg/L, are prepared in the cylindrical cell incorporated with sensors for measuring electrical resistance and time domain reflectometry signal. Then, the dried sands are water-pluviated into the cell. The electrical resistance and the time domain reflectometry signal are used to estimate the electrical conductivity. Test results show that electrical conductivity determined from electrical resistance at the frequency of 1 kHz continuously increases with an increase in the lead concentration, thus it may be used for the estimation of the contaminant level. In addition, the electrical conductivity estimated by the time domain reflectometry changes even at very low concentration of lead, the variation rate decreases as the lead concentration increases. Thus, the time domain reflectometry can be used for the investigation of the heavy metal leakage. This study demonstrates that complementary characteristics of electrical resistance and time domain reflectometry may be used for the detection of the leakage and contamination of heavy metal in coastal and marine environments.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.360-368
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• 2006

Objective: Surface characteristics of dental materials play an important role in bacterial adhesion. The purpose of this study was to investigate surface characteristics of 5 different light-cured orthodontic adhesives (1 fluoride-releasing composite, 3 non-fluoride-releasing composites, and f resin-modified glass ionomer). Methods: Surface roughness was measured using a confocal laser scanning microscope. Contact angle and surface free energy components were analyzed using the sessile drop method. Results: Surface roughness was significantly different between adhesives despite a relatively small variation (less than $0.05\;{\mu}m$). Lightbond and Monolok2 were rougher than Enlight and Transbond XT. There were also significant differences in contact angles and surface free energy components between adhesives. In particular, considerable differences in contact angles and surface free energy components were found between resin modified glass ionomer and the composites. Resin modified glass ionomer showed significantly smaller contact angles in 3 different probe liquids and had higher total surface free energy and stronger polarity, with notably stronger basic property than the composites. Conclusion: Resin modified glass ionomer may provide a more favourable environment for bacterial adhesion than composite adhesives.

• Horticultural Science & Technology
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• v.31 no.3
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• pp.344-351
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• 2013

Microsatellite is one of the most suitable marker for cultivar identification as it has great discrimination power for cultivars with narrow genetic variation. The polymorphism level between 358 microsatellite primer pairs and 11 commercial cucumber cultivars was investigated. Thirty-one primer pairs showed high polymorphism within cucumber cultivars with different fruit types. These markers were applied for the constructing DNA profile data base of 110 commercial cucumber cultivars through multiplex PCR and fluorescence based automatic detection system. A total of 139 polymorphic amplified fragments were obtained by using 31 microsatellite markers. The average of PIC value was 0.610 ranging from 0.253 to 0.873. One hundred and thirty nine microsatellite loci were used to calculate Jaccard's distance coefficients for UPGMA cluster analysis. A clustering group of varieties, based on the results of microsatellite analysis, were categorized into plant shape and fruit type. Almost the cultivars were discriminated by marker genotypes. This information may be useful to compare through genetic relationship analysis between existing variety and candidate varieties in distinctive tests and protection of plant breeders' intellectual property rights through variety identification.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.270-278
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• 1991

Carboxymethyl chitin(CM-chitin) was prepared by the reaction of alkali chitin with monochloroacetic acid in isopropyl alcohol. According to the pH variation, the adsorptivity of this chelating polymer to the alkali-earth metal ions such as $Ca^{2+},\;Mg^{2+}$, $Sr^{2+}$, $Ba^{2+}$ ions was determined by batch method. The adsorption tendency of this chelating polymer to most metal ions was increased with the increase of pH. The highest degree of adsorption was observed toward $Ca^{2+}$ ion among the alkali-earth metal ions. The selectivity adsorption property toward $Ca^{2+}$ ion was examined in the solution of $Ca^{2+}$ and $Mg^{2+}$ ions, and it was observed that CM-chitin showed excellent selectivity to $Ca^{2+}$ ion than $Mg^{2+}$ ion. $Mg^{2+}$ ion bound to CM-chitin molecule in the presence of $Ca^{2+}$ ion owing to low equilibrium constant. In the adsorption experiment of $Ca^{2+}$ and $Mg^{2+}$ ions to the CM-chitin under coexistence of $Na^+$ and $K^+$ ions, it observed that adsorptivity of only $Ca^{2+}$ ions was not affected by these monovalent cations.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.213-220
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• 2009

The optimal condition of low temperature deposition of transparent conductive Al-doped zinc oxide (AZO) films is studied by RF magnetron sputtering method. To achieve enhanced-electrical property and good crystallites quality, we tried to deposit on glass using a two-step growth process. This process was to deposit AZO buffer layer with optimal growth condition on glass in-situ state. The AZO film grown at rf 120 W on buffer layer prepared at RF $50{\sim}60\;W$ shows the electrical resistivity $3.9{\times}10^{-4}{\Omega}cm$, Carrier concentration $1.22{\times}10^{21}/cm^3$, and mobility $9.9\;cm^2/Vs$ in these results, The crystallinity of AZO film on buffer layer was similar to that of AZO film on glass with no buffer later but the electrical properties of the AZO film were 30% improved than that of the AZO film with no buffer layer. Therefore, the cause of enhanced electrical properties was explained to be dependent on degree of crystallization and on buffer layer's compressive stress by variation of $Ar^+$ ion impinging energy.

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.218-222
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• 2000

W-Ti film properties for X-ray absorber applications have been investigated with Ti composition have been investigated with Ti composition variation. W-Ti films were deposited by DC magnetron sputtering system. As the working pressure increases, film density decreases and film stress changes from compressive to tensile. The transition pressure (where the film stress in zero) and the stress gradient decrease by adding Ti into W-Ti(6.5 at.%) film shows the smallest stress gradient and transition pressure. It also shows high density ($17.7g/\textrm{cm}^3$) similar to that of pure-W ($17.8g/\textrm{cm}^3$) at the transition pressure. All the films show columnar structure, and its size decreases with increasing Ti composition. Surface roughness and thermal stability are improved by Ti-addition, resulting in a better property for X-ray absorber applications.

• Polymer(Korea)
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• v.29 no.2
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• pp.177-182
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• 2005

Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol, $Nippollan4010(\bar{M}_n2000)$. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in $25\;wt\%$ solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of $PU/Na^+-MMT$ composites.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.3
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• pp.132-140
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• 1994

SCRIPT (Symbol/Character Recognition In Pen-based Technology) is an algorithm for on-line recognition of handwriting Hangeul. English upperacase letters, decimal digits, and some keyboard symbols. The shape of handwriting symbols has a large variation even when written by the same person. Though the feature analysis approach using a conventional decision tree is efficient, it is not robust under shape variations and prone to misclassification. Thus, a new method to overcome this shortcoming is necessary. In this paper, a feature analysis algorithm using two fuzzy decision trees which utilize the hierarchical property of the pattern is proposed. The first tree is used to represent the stroke shape, and the other tree is used to represent the relation between the strokes. since this method stores various possibilities. it is robust to shape variations and can readily modify false selections. In addition, there is a large increase in the recognition rate of high-level patterns due to low-level candidated. Experimental results show 91% recognition rate for Hangeul at the recognition speed of 0.33 second per character, and the recognition rate of alphanumerics and some keyboard symbols is 95% at 0.08 second per symbol. This is 8~18% increase in the recognition rate over th method not applying fuzzy decision trees.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.247-255
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• 2005

ice yield and plant growth response to nitrogen (N) fertilizer may vary within a field, probably due to spatially variable soil conditions. An experiment designed for studying the response of rice yield to different rates of N in combination with variable soil conditions was carried out at a field where spatial variation in soil properties, plant growth, and yield across the field was documented from our previous studies for two years. The field with area of 6,600 m2 was divided into six strips running east-west so that variable soil conditions could be included in each strip. Each strip was subjected to different N application level (six levels from 0 to 165kg/ha), and schematically divided into 12 grids $(10m \times10m\;for\;each\;grid)$ for sampling and measurement of plant growth and rice grain yield. Most of plant growth parameters and rice yield showed high variations even at the same N fertilizer level due to the spatially variable soil condition. However, the maximum plant growth and yield response to N fertilizer rate that was analyzed using boundary line analysis followed the Mitcherlich equation (negative exponential function), approaching a maximum value with increasing N fertilizer rate. Assuming the obtainable maximum rice yield is constrained by a limiting soil property, the following model to predict rice grain yield was obtained: $Y=10765{1-0.4704^*EXP(-0.0117^*FN)}^*MIN(I-{clay},\;I_{om},\;I_{cec},\;I_{TN},\; I_{Si})$ where FN is N fertilizer rate (kg/ha), I is index for subscripted soil properties, and MIN is an operator for selecting the minimum value. The observed and predicted yield was well fitted to 1:1 line (Y=X) with determination coefficient of 0.564. As this result was obtained in a very limited condition and did not explain the yield variability so high, this result may not be applied to practical N management. However, this approach has potential for quantifying the grain yield response to N fertilizer rate under variable soil conditions and formulating the site-specific N prescription for the management of spatial yield variability in a field if sufficient data set is acquired for boundary line analysis.

• Economic and Environmental Geology
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• v.14 no.3
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• pp.111-122
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• 1981

This study is a model analysis for an effective application of the geophysical prospecting to the investigation of geological structures or useful resources, and the purpose of it is to research a property of the electrical resistivity prospecting, especially by using a Three-Point electrode array method. In using the Three-Point electrode array method, it is theoretically assumed to choose the infinite for a distance between the two current electrodes, however it is impossible in applying to the practical field prospecting. Therefore this study was conducted for determination and presentation of a minimum appropriate distance between the two current electrodes by making a study on prospecting effect in the variation of distance between both the electrodes. In case that the ratios of the distance between the two current electrodes to that between the two potential electrodes are respectively chosen for 40, 400, 5,000, the experimental data of this study showed that the minimum appropriate distance between the two current electrodes is forty times as much as that between two potential electrodes. In order to make clear a problem about prospecting depth which is essential to the data processing, it had been chosen equally to the distance between two potential electrodes. As a result of it, it was shown that the anomaly is appeared along the position of an assumed ore body. Consequently it was found out that the prospecting depth of the Three-Point electrode array method is the same as the distance between the two potential electrodes. From the model experiment on the sheeting ore body(or linear structure) of horizontal, dipping of $30^{\circ}$, $60^{\circ}$ and vertical on the basis of above experimental condition, it was found out that the position and dip of assumed ore body could be inferred from the aspects of the equiresistivity curve. In consequence of performing out the simultaneous Normal and Reversal electrode movement, it was shown that the electrode movement of the Reversal forms the anomaly more clearly than that of Normal when the sheeting ore body is situated obliquely, therefore it could be ascertained that the electrode movement have to be performed simultaneously in the manner of Normal and Reversal. It was also exhibited that the aspect of the equiresistivity curve forms symmetrically when an assumed ore body (or linear structure) is situated horizontally or vertically, that is, symmetrically, and moreover that the aspect of the equiresistivity curve forms unsymmetrically when an assumed ore body (or linear structure) is situated obliquely. On the basis of these experimental analysis it is thought that it can be inferred from the aspect of equiresistivity curve whether an assumed ore body is obliquely situated or not.