• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.616-623
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• 1994

Conductive Polypyrrole films have been synthesized by electrochemical method in nucleophilic solvent such as N, N-dimetylformamide(DMF), dimethylsulfoxide(DMSO). The effect of protic acid as supporting electrolyte to decrease the nucleophilicity of the solvent was studied. Cyclic voltammetry, I-t transients were carried out to investigate the electrodeposition of conductive polypyrrole film on platinum electrode. Three peaks of 0.65V, 0.85V, and 1.2V vs. $Ag/AgNO_3$ indicated oxidation of monomer, oxidation of pyrrole to the platinum electrode and decomposition of polypyrrole film, respectively. With the I-t transients, nucleation process was confirmed and from obtained linear fits of I vs.t2resembles the metal film formation, and 2.15-2.26 of n-value could be calculated. As concentration of pyrrole or prolic acid was increased, the conductivity of polypyrrole film increased linearly. Tensile strength and elongation were investigated for comparing the mechanical properties and also SEM was performed for morphology investigation.

• Korean journal of food and cookery science
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• v.17 no.4
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• pp.353-358
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• 2001

The leaves of Duchung(Eucommia ulmoides), an oriental medicinal plant, have a peculiar aroma of Chinese medicine and astringent taste, which make the consumer be reluctant to Duchung leaf tea. Therefore, the purpose of this study was to develop a mild flavored Duchung leaf tea by mixing with other plants. The flavor patterns of developed tea were analyzed using an electronic nose. Polygonatum odoratum and Elsholtzia splendens were used for improving the flavor of Duchung leaf tea. The addition of 20, 30 and 40% of Polygonatum odoratum improved the overall acceptance in hedonic sensory evaluation. The flavor pattern of the tea was described by principal component analysis(PCA) and the resistance ratio(R/cub gas/R$\_$air/) of sensors. The PCA plot was also used to explain the mild flavor of the tea, which was extended from the right side(positive value of the first principal component) to the left side(negative value). Analysis by using an electronic nose with metal oxide sensors could be applied to detect whether mixed Duchung leaf tea was acceptable or not.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.3
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• pp.226-232
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• 1988

Non-enzymatic browning is a carbohydrate dehydration reaction, accelerated thorough the interaction of amino compounds. Reaction depends on several factors including temperature, reactant concentration, pH, water activity and specific ion concentrations, and result in progressive development of brown pigments in the affected food systems. The present study was designed to utilize a kinetic approach to analyze the effect of temperature and water activity on the browning development in green ten. The green tea was controlled at aw of 0.33, 0.44, 0.52 and 0.65 using saturated salt solutions and then stored at 35,45 and $55^{\circ}C$. Author portion of the sample of which the water activities were controlled in the same manner was stored at 35 and $55^{\circ}C$ alternately with 7 days interval. Simplified kinetic models were used to obtain the various kinetic parameters for browning development in green tea subjected to accelerated shelf-life tests(ASLT). The reaction of browning development was zero order. The activation energies calculated from Arrhenius plot ranged $1.5{\sim}2.4kcal/mole$ and $Q_{10}$ values were between 1.07 and 1.12. These kinetic parameters were then used to predict browning development under the nonsteady storage. Assessed from the parameters the shelf-lives at $25^{\circ}C$, the time to reach 1.02 O.D./g solid at which severe brown color change could be detectable, ranged 57 to 113 days and showed decrease with increase in aw. The predicted shelf-lives at different water activities were a little higher than actual values.

• Journal of Ginseng Research
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• v.35 no.1
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• pp.31-38
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• 2011

In order to distinguish the cultivation area of Panax ginseng, principal component analysis (PCA) using quantitative and qualitative data acquired from HPLC was carried out. A new HPLC method coupled with evaporative light scattering detection (HPLC-ELSD) was developed for the simultaneous quantification of ten major ginsenosides, namely $Rh_1$, $Rg_2$, $Rg_3$, $Rg_1$, Rf, Re, Rd, $Rb_2$, Rc, and $Rb_1$ in the root of P. ginseng C. A. Meyer. Simultaneous separations of these ten ginsenosides were achieved on a carbohydrate analytical column. The mobile phase consisted of acetonitrile-water-isopropanol, and acetonitrile-water-isopropanol using a gradient elution. Distinct differences in qualitative and quantitative characteristics for ginsenosides were found between the ginseng roots produced in two different Korean cultivation areas, Ganghwa and Punggi. The ginsenoside profiles obtained via HPLC analysis were subjected to PCA. PCA score plots using two principal components (PCs) showed good separation for the ginseng roots cultivated in Ganghwa and Punggi. PC1 influenced the separation, capturing 43.6% of the variance, while PC2 affected differentiation, explaining 18.0% of the variance. The highest contribution components were ginsenoside $Rg_3$ for PC1 and ginsenoside Rf for PC2. Particularly, the PCA score plot for the small ginseng roots of six-year old, each of which was light than 147 g fresh weight, showed more distinct discrimination. PC1 influenced the separation between different sample sets, capturing 51.8% of the variance, while PC2 affected differentiation, also explaining 28.0% of the variance. The highest contribution component was ginsenoside Rf for PC1 and ginsenoside $Rg_2$ for PC2. In conclusion, the HPLC-ELSD method using a carbohydrate column allowed for the simultaneous quantification of ten major ginsenosides, and PCA analysis of the ginsenoside peaks shown on the HPLC chromatogram would be a very acceptable strategy for discrimination of the cultivation area of ginseng roots.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.177-182
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• 2011

A diketo-type ligand was synthesized by the Knoevenagel condensation reaction of thiophene-2-aldehyde with acetylacetone, subsequently its transition metal complexes with Cu(II), Ni(II), and Co(II) chlorides were also prepared. All the complexes were characterized by various physico-chemical methods. The molar conductivity data reveals ionic nature for the complexes. The electronic spectrum and the EPR values suggest square planar geometry for the Cu(II) ion. Interaction of the Cu(II) complex with CTDNA (calf thymus DNA) was studied by absorption spectral method and cyclic voltammetry. The $k_{obs}$ values versus [DNA] gave a linear plot suggesting psuedo-first order reaction kinetics. The cyclic voltammogram of the Cu(II) complex reveals a quasi-reversible wave attributed to Cu(II)/Cu(I) redox couple for one electron transfer with $E_{1/2}$ values -0.240 V and -0.194 V. respectively. On addition of CTDNA, there is a shift in the $E_{1/2}$ values 168 mV and 18 mV respectively and decrease in Ep values. The shift in $E_{1/2}$ values in the presence of CTDNA suggests strong binding of Cu(II) complex to the CTDNA.

• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.448-463
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• 2006

This study analyzed the changes in vegetation structure of Quercus mongolica communities, Pinus densiflora communities, Robinia pseudo-acacia communities and Pinus rigida communities for the last 11 years$(1994{\sim}2005)$ to provide basic data for ecological restoration. We studied the vegetation structure of four communities within a plot$(unit:\;1,200m^2)$) and concluded that Canopy Layer continuously preserved and expanded existing superior species, Understory Layer grew Styrax japonica which is highly adaptive to urban environment, and Shrub Layer grew more Stephanandra incise. An analysis on species diversity indicated that Quercus mongolica communities$(1.0921{\rightarrow}1.0381{\rightarrow}1.0633)$, Pin us densiflora communities$(0.7071{\rightarrow}0.8553{\rightarrow}1.0164)$, and Robinia pseudo-acacia communities$(0.9255{\rightarrow}0.8392{\rightarrow}0.8721)$ sharply decreased in 1998 and are gradually increasing these days. Also, Pinus rigida communities decreased from 0.9008 in 1998 to 0.8850 in 2005. Fluctuation in numbers of species and trees were similar. Acidity of soil was $4.34{\sim}5.31$ and improved compared to 20 years ago.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.391-400
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• 2017

Italian ryegrass (IRG) is one of the fastest growing grasses available to farmers. It offers rapid establishment and starts growing early in the following spring and has fast regrowth after defoliation. So, IRG can be utilized as the dominant/single species of grass used in a farming system, or to play a role as a large producing pasture and sacrificial paddock. The objective of this study was to develop the use of unmanned aerial vehicle (UAV) for the evaluation of feed value of IRG. For this study, UAV imagery was taken on the Nonsan regions two times during the IRG growing season. We analyzed the relationships between $NDVI_{UAV}$ and feed value parameters such as fresh matter yield, dry matter yield, acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrient (TDN) and crude protein at the season of harvest. Correlation analysis between $NDVI_{UAV}$ and feed value parameters of IRG revealed that $NDVI_{UAV}$ correlated well with crude protein (r = 0.745), and fresh matter yield (r = 0.655). According to the relationship, the variation of $NDVI_{UAV}$ was significant to interpret feed value parameters of IRG. Eight different regression models such as Linear, Logarithmic, Inverse, Quadratic, Cubic, Power, S, and Exponential model were used to estimate IRG feed value parameters. The S and exponential model provided more accurate results to predict fresh matter yield and crude protein than other models based on coefficient of determination, p- and F-value. The spatial distribution map of feed values in IRG plot was in strong agreement with the field measurements in terms of geographical variation and relative numerical values when $NDVI_{UAV}$ was applied to regression equation. These lead to the result that the characteristics of variations in feed value of IRG according to $NDVI_{UAV}$ were well reflected in the model.

• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.56-66
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• 2020

Purpose: A stability-measuring device that utilizes damping capacity analysis (DCA) has recently been introduced in the field of dental implantology. This study aimed to evaluate the sensitivity and reliability of this device by measuring the implant stability of ex vivo samples in comparison with a resonance frequency analysis (RFA) device. Methods: Six implant beds were prepared in porcine ribs using 3 different drilling protocols to simulate various implant stability conditions. Thirty-six pork ribs and 216 bone-level implants measuring 10 mm in height were used. The implant beds were prepared using 1 of the following 3 drilling protocols: 10-mm drilling depth with a 3.5-mm-diameter twist drill, 5-mm drilling depth with a 4.0-mm-diameter twist drill, and 10-mm drilling depth with a 4.0-mm-diameter twist drill. The first 108 implants were external-connection implants 4.0 mm in diameter, while the other 108 implants were internal-connection implants 4.3 mm in diameter. The peak insertion torque (PIT) during implant placement, the stability values obtained with DCA and RFA devices after implant placement, and the peak removal torque (PRT) during implant removal were measured. Results: The intraclass correlation coefficients (ICCs) of the implant stability quotient (ISQ) results obtained using the RFA device at the medial, distal, ventral, and dorsal points were 0.997, 0.994, 0.994, and 0.998, respectively. The ICCs of the implant stability test (IST) results obtained using the DCA device at the corresponding locations were 0.972, 0.975, 0.974, and 0.976, respectively. Logarithmic relationships between PIT and IST, PIT and ISQ, PRT and IST, and PRT and ISQ were observed. The mean absolute difference between the ISQ and IST values on a Bland-Altman plot was -6.76 (-25.05 to 11.53, P<0.05). Conclusions: Within the limits of ex vivo studies, measurements made using the RFA and DCA devices were found to be correlated under a variety of stability conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.2
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• pp.105-109
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• 2004

Field studies were conducted in the southeastern Korea ($36^{\circ}$N) on a commerce silt loam soil at paddy field. Seed were manually planted on 16 July 2003. Plants were planted with plant densities of 70${\times}$10 cm (row width x plant spacing), 50 x 10 cm, and 30 ${\times}$10 cm. Two seedlings per hill were taken prior to V3 stage. Fertilizer was applied prior to plant at a rate of 30-30-34 kg (N-$\textrm{P}_2\textrm{O}_5$-$\textrm{K}_2\textrm{O}$) per ha. Experimental design was a randomized complete block in a split plot arrangement with three replications. Yield from different planting densities responded similarly in three soybean cultivars and increased when planting density increased. Somyeongkong showed the highest increasing rate of yield about 26% by 338 g $\textrm{m}^{-2}$ at 30 x l0 cm compared to yield of conventional planting density (70 x 10 cm). Also, the planting density significantly affected pod and seed number and seed weight, but not seed per pod. The tallest plant appeared at 30${\times}$10 cm. The change of leaf area according to days after emergence showed differently in soybean cultivars. The highest and lowest total dry matter production per square meter appeared at 30 x 10 cm and at 70 x 10 cm, respectively. Crop growth rate (CGR) showed greater at R3∼R4 stages compared with V7∼R2 or R2∼R3 growth stages and showed the greatest at 30 x 10 cm in three soybean cultivars. As late planted soybean, there was a significant relation between seed yield and CGR, and leaf area index (LAI) according to planting densities at before and after the flowering stage. Relationship between seed yield and CGR in three planting densities showed a highly significant positive relation ($\textrm{R}^2$=0.757) at R3 to R4 stages, and significant relations ($\textrm{R}^2$=0.505, 0.617) at V7 to R2 and V2 to V3. Also, there was a highly significant positive difference between seed yield and LAI during R3 to R4 and R2 to R3 stages.

• Korean Journal of Environmental Agriculture
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• v.7 no.1
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• pp.26-33
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• 1988

To investigate the effects of paper sludge on the growth response of paddy rice, paper sludge was applied to pots at the rate of either 300, 600, 900 or 1,200 kg/l0a which was either preadjusted at a C/N ratio of 30 : 1 or not adjusted. The effects were compared with those of the control. 1. Plant heights, number of tillers and dry weight were significantly reduced with the increasing application of paper sludge in the early stages of rice growth, whereas opposite results were observed after the heading stage when treated with C/N ratio preadjusted paper sludge. 2. The uptake of $N,P_2O_5,K_2O$ and $SiO_2$ by rice plants grown in paper sludge treated soil was significantly reduced in the early stages of rice growth. Conversely, uptake was enhanced in the C/N ratio preadjusted plot in the young panicle formation stage. 3. Zn, Cu and Cd content in rice straw was in the range of $39{\sim}101$, $0{\sim}0.11$ and $0.03{\sim}0.14ppm$, respectively, and Pb and Cr in rice straw were not detected at all. However, there was no difference in the content of all these heavy metals in rice straw irrespective of treatment.