• Journal of Korea Water Resources Association
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• v.38 no.12 s.161
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• pp.985-994
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• 2005

We examined problems of the principal component analysis(PCA), which is able to analyze at the low dimensionality as a methodologv to assess hydrologic time series, and introduced the theory and characteristics of independent component analysis(ICA) that can supplement problems of principal component analysis. We also applied the global sea surface temperature(SST) of the Nino region and assessed the correlation between El $\tilde{n}ino$-Southern Oscillation(ENSO) and SST. The results of examining separation-ability of principal components using mixed signals indicate that the independent component analysis is statistically superior compared to that of the principal component analysis. Finally, we assessed correlation between ENSO and global anomaly SST. The independent component analysis was applied to the $5^{\circ}{\times}5^{\circ}$(latitude and longitude) global anomaly SST in the Nino+3.4 region that is the El $\tilde{n}ino$ observation section. We assessed the correlation with the ENSO years. These results of the analysis show that only one independent component($86\%$) was able to represent the entire behavior and was consistent with the main ENSO years. Finally, we carried out independent component analysis for summer seasonal rainfalls at nine stations and could extract ICs to reflect geographical characteristics. The increasing trend has been shown at IC-1 and IC-2 since 1970s.

• Analytical Science and Technology
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• v.6 no.5
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• pp.489-499
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• 1993

Some sorption behaviors of U(VI) ion on Arsenazo I-XAD-2 chelating resin were investigated. This chelating resin was synthesized by the diazonium coupling of Amberlite XAD-2 resin with Arsenzo I chelating reagent and characterized by elementary analysis method and IR spectrometry. The optimum conditions for the sorption of U(VI) ion were examined with respect to pH, U(VI) ion concentration and shaking time. Total sorption capacity of this chelating resin on U(VI) ion was 0.39mmol U(VI)/g resin in the pH range of 4.0~4.5. This chelating resin was showed increased sorption capacity on the increased pH value. It was confirmed that sorption mechanism of U(VI) ion on the Arsenazo I-XAD-2 chelating resin was competition reacting between U(VI) ion and $H^+$ ion. Breakthrough volume and overall capacity of U(VI) ion measured by column were was 600 ml and 0.38 mmol U(VI)/g resin, respectively. The desorption of U(VI) ion was showed recovery of 90~96% using 3M $HNO_3$ and 3M $Na_2CO_3$ as a desorption solution. The separation and concentration of U(VI) ion from natural water and sea water was performed successfully by Arsenazo I-XAD-2 chelating resin.

• Cartoon and Animation Studies
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• s.40
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• pp.337-365
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• 2015

The objective of this study proposes the new user's addiction model in 'Social Network Games' (SNGs). Research model is derived from the separation of two characteristics. First one is logical characteristics that includes 'Functional' (F), 'Keystroke' (K), and 'Goal' (G). Second one is feeling characteristics that consists a few factors such as 'Emotion' (E), 'Social' (S), and 'Affection' (A). For the pre-test, a total of 30 participants responded to survey in order to inspect the fitness of research questionnaire, roughly validity of the proposed model, and the direction of this reseach. After that for the main test, a total 300 users participated in this research. The final number of effective participants were 261 because 39 were insincere respondents and without playing SNGs who were excluded. Then we examined the measurement model by performing 'Partial Least Squares - Structural Equation Modeling' (PLS-SEM) analysis to test the research hypothesis empirically. The results of the measurement and structural model test lend support to the proposed research model by providing a good fit to the construct data. Interestingly, the model showed the significant effects of the interaction between eleven hypothesis(H1,H2,H3,H4,H5,H6,H7,H8,H9,H10, H12). Only one hypothesis decision t-value not supported that is involved the relationship between SNGs Addiction and Keystroke, H11(1.193). This research expect to contributes to an exploratory SNGs research to clarify the base of addition and will aids understanding of users' behavior associated with SNGs development.

• Journal of the Korean Magnetics Society
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• v.10 no.3
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• pp.133-138
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• 2000

We have investigated some crystallographic, magnetic, and transport properties of the first colossal magnetoresistive compounds $La_{1-x}Ba_{x}MnO_3(0\leq\chi\leq$1)$(5\;K\leqT\leq360K,-5T\leqH\leq5T$ and resistivity $(100K\leqT\leq350K$measurements. $La_{1-x}Ba_{x}MnO_3$ were found to be ferromagnetic for all x.The $La_{1-x}Ba_{x}MnO_3$were found to be insulating for x< 0.2, metallic for 0.20.5. The magnitude of saturation magnetization (Ms) increased until x=1/8 and had theoretical maximum Ms for 0.13$\sfrac{3}{8}$ and had a constant value of 335~340 K for x>$\sfrac{3}{8}$. For $x\geq0.5$ the $La_{1-x}Ba_{x}MnO_3$ samples showed a percolation-type conduction behavior and enhanced low field magnetoresistance caused by simultaneous occurrence of the chemical/magnetic phase separation.

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.276-281
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• 2009

Electrochemical behaviors of $U^{3+}$ and $Gd^{3+}$ were investigated in LiCl-KCl eutectic molten salt by using various electrochemical techniques. The electrodeposition and dissolution currents for uranium show the maximum at -1.51V and -1.35V, respectively while, for gadolinium,at -2.15V and -1.9V, respectively. In case of LiCl-KCl molten salt containing both of $U^{3+}$ and $Gd^{3+}$, the peak potential of electrodeposition of gadolinium shifts to more positive potential than in the solution without $U^{3+}$. The potentials in chronopotentiometric data suddenly dropped to negative value as soon as the reduction currents were applied and became constant at the potential around which the $U^{3+}$ and $Gd^{3+}$ are electrodeposited. The results of normal pulse voltammetry (NPV) and square wave voltammetry show that those methods can be used to qualitatively analyze the elements in the melts. Especially, the differentiation of NPV result was found to be useful for the separation of the peaks of which potentials are close each other.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.264-269
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• 2001

Large amounts of orange juice are produced in Japan every yea.. Accompanied by the production of orange juice, large amount of juice residues are also generated in nearly the same amounts with juice. Although, at present, some of these residues are marketed as a feed for cattle after drying and mixing with lime, the marketing price is lower than its production cost and the difference is paid by the consumers as a part of the price of orange juice. In the present work, we developed new innovative use of orange juice residue, a biomass waste, as adsorption gel for removing toxic heavy metals such as lead. arsenic, selenium and so on as well as radioactive elements such as uranium and thorium from environments. The major components of orange juice residue are cellulose. hemicellulose and pectin, which are converted into pectic. acid, an acidic polysaccharide, by means of saponification with concentrated sodium hydroxide solution. In the previous work, we found that crosslinked pectic acid gel strongly an selectively adsorbs lead over other metals such as zinc an copper. On the other hand. it is well known that polysaccharides such as cellulose can be easily phosphorylated and that phosphorylated polysaccharides have high affinity to uranium and thorium as well as some trivalent metals such as ferric iron and aluminum. Taking account of the noticeable characteristics of these polysaccharides, 2 types of adsorption gels were prepared from orange juice residue: one is the gel which was prepared by saponificating the residue followed by crosslinking with epichlorohydrin and another is that prepared by crosslinking the residue followed by phosphorylation. The former gel exhibited excellent adsorptive separation behavior for lead away from zinc owing to high content of pectic acid while the latter gel exhibited that for uranium and thorium. Both types of adsorption gels exhibited high affinity to ferric iron, which enables selective and strong adsorption for some toxic oxo-anions of arsenic (V and III), . selenium and so on via iron loaded on these gels. These results demonstrate that biomass wastes such as orange juice residue can be effectively utilized fer the purpose of removing toxic heavy or radioactive metals existing in trace or small amounts in environments.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.697-708
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• 1992

Liquid Chromatographic behavior of Ni(II) in Isonitrosoethylacetoacetate Imine(IEAA-NR), Ni(IEAA-NH)(IEAA-NR)(R = H, CH_3, C-2H_5, n-C_4H_9, C_6H_5-CH_2) chelates were investigated by reversed-phase HPLC on Micropak MCH-5 column using methanol/water as mobile phase. The optimum conditions for the separation of Ni(IEAA-NH)(IEAA-NR) chelates were examined with respect to the effect of the flow rate, sample solvent, mobile phase strength and column temperature. It was fo$und that metal chelates were properly eluted in an acceptable range of capacity factor value(0{\le}logk'{\le}1). The dependence of the logarithm of capacity factor (k') on the volume fraction of water in the binary mobile phase as well as on the liquid-liquid extraction distribution ratio (Dc) in methanol-water/n-alkane extraction system showed the good linearties, and the dependence of the logarithm of capacity factor (k') on the column temperature and on the enthalpy exhibited the good linearties, and the compensation temperature ({\beta}) from the slope was 773.47{\circ}K. It was suggested that the retention of metal chelates was largely affected by the hydrophobic effect.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.149-152
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• 2012

$Cu(In,Ga)Se_2$ (CIGS) is one of the most promising photovoltaic materials because of large conversion efficiency which has been achieved with an optimum Ga/(In+Ga) composition in $CuIn_{1-x}Ga_xSe_2$ (X~0.3). The Ga/(In+Ga) content is important to determine band gap, solar cell performances and carrier behaviors at grain boundary (GB). Effects of Ga/(In+Ga) content on physical properties of the CIGS layers have been extensively studied. In previous research, it is reported that GB is not recombination center of CIGS thin-film solar cells. However, GB recombination and electron-hole pair behavior studies are still lacking, especially influence of with different X on CIGS thin-films. We obtained the GB surface potential, local current and I-V characteristic of different X (00.7 while X~0.3 showed higher potential than 100 mV on GBs. Higher potential on GBs appears positive band bending. It can decrease recombination loss because of carrier separation. Therefore, we suggest recombination and electron-hole behaviors at GBs depending on composition of X.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.673-680
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• 2019

GAP or GAP-co-BO based energetic thermoplastic elastomers (ETPEs) were synthesized by changing the hard segment content percent in the range of 30~45% by 5% difference. Thermal and mechanical properties of GAP-co-BO based ETPEs were compared to those of GAP based ETPEs. FT-IR results showed that the capability of forming hydrogen bond increases with increasing the hard segment content in GAP/GAP-co-BO based ETPE, and also the GAP-co-BO based ETPEs are stronger than GAP based ETPEs in the hydrogen bond formation. DSC and DMA results showed that the glass transition temperature (T_g) of GAP based ETPEs increased with the increment of the hard segment content, while the T_g of GAP-co-BO based ETPEs was maintained even the hard segment content increased. The storage modulus at room temperature of the GAP-co-BO based ETPEs was higher than that of the GAP based ETPEs. This was due to the strong phase separation behavior of the hard and soft segment of GAP-co-BO based ETPEs, which further resulted in the stronger breaking strength and lower tensile elongation at break point for GAP-co-BO based ETPE than the GAP based one.

• Resources Recycling
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• v.15 no.5 s.73
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• pp.17-25
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• 2006

Al-MCM-48 was used as a catalyst to decompose high density polyethylene(HDPE). Catalytic activity of Al-MCM-48 was compared with those of Al-MCM-41, Beta, and ZSM-5. Catalytic decomposition rate over Al-MCM-48 was much higher than at of non-catalytic pyrolysis only. Compared to other catalysts, Al-MCM-48 revealed the little higher activation energy value. The progressive deactivation behavior of the catalysts has also studied. ZSM-5 and Al-MCM-48 showed slower deactivation rates than Al-MCM-41 and Beta. Pyrolysis coupled with gas chromatographic separation and flame ionization detection (Py-GC/ FID) was also performed to assess the characteristics of pyrolysis products. ZSM-5 gave a higher fraction of gaseous products ($C_1-C_4$). Al-MCM-41 and Beta produced mainly $C_5-C_{12}$ products. The selectivity to oil product ($C_5-C_{22}$) obtained with Al- MCM-48 is higher an that with the other catalysts employed in this study.