• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.70-81
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• 1989

Reverse phase liquid chromatographic elution behaviors of salicylic acid and its derivatives were studied with classical and modern high-performance liquid chromatography(HPLC) using Amberlite XAD-4 and XAD-7 resin packed columns. Capacity factors(k') were determined in the comparatively high concentration(from 0. 010F to 0. 150F) of ferric nitrate-50% methanol solution to elucidate the elution behaviors with classical method. On the other hand, k's were measured in the various concentrations of methanol and ferric nitrate(from $2.5{\times}10^{-4}F\;to\;1.0{\times}10^{-3}F$) solution of pH 2. 25 and 293K with HPLC to explain the elution mechanism of them, and to find their optimum separation condition. As a result, it was found that log k's of salicylic acid and its derivatives were decreased with increasing the concentration of ferric ion, and the decreasing slopes of the compounds on the increasing ferric ion concentrations were related with each stability constant of ferric salicylates. Some isomers of derivatives of salicylic acid could be separated in the optimum condition.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.37-45
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• 1989

Voltammetric behavior of alkylammonium ion was studied in the absence and in the presence of crown ether in propylene carbonate as solvent. The peak potentials and the peak currents, their dependency on the concentrations, the reversibility of the electrode reactions are described. In the presence of crown ether chemical reaction might be preceeded before the electron-transfer process, the peak potential for the reduction shifts at the negative direction as the concentration of crown ether to the electrolyte solution increases. The addition of crown ether(20mM 18CR6)to the electrolyte solution made it possible to determine voltammetrically the dialkylammonium ions($Me_2NH^{+}_{2};O.6{\sim}0.8mM$) in the presence of the monoalkylammonium ions ($EtNH^{+}_{3} ;1.6mM$) and the monoalkylammonium ions ($EtNH^{+}_{3} ; 0.5{\sim}2.5mM$) in the presence of the dialkylammonium ions($Me_2NH^{+}_{2};0.5mM$)

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.369-377
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• 1998

The palladium(II) and platinum(II) complexes(where, $([M(L)_2X_2]$, M=Pd(II), Pt(II); L=isoxazole(isox), 3,5-dimethylisoxazole(3,5-diMeisox), 3-methyl, 5-phenylisoxazole(3-Me, 5-Ph-isox), and 4-amino-3,5-dimethylisoxazole (4-ADI); X=Cl, Br) with isoxazole and its derivatives were investigated on antitumor activity by MM2 and EHMO calculation. Because for all the complexes the ${\sigma}MO$ energy level $(E_{{\sigma}(M-X)})$ between $d_x^{2-}_y^2$ orbital of central metal and px orbital of halogen atom is less than ${\sigma}MO$ energy level $(E_{{\sigma}(M-N)})$ between $d_x^{2-}_y^2$ orbital of central metal and px orbital of N atom, without exception. And judging, from the lower $(E_{\'{o}(m-x)})$ value in trans, the bonding strength was found to be weaker in trans isomer than in cis. For the Pd(II) and Pt(II) complexes which have planar ligands, it was shown that for all the complexes dissociation of X-atom in the Pd(II) complexes is easier than that of X-atom in the Pt(II) complexes in both cis- and trans-complexes. Therefore it suggests that the easier dissociation of $X^-$ ion has some relations with antitumor activity, and a linear equation with correlation coefficient of 0.96 was found between ${\Delta}E_{{\sigma}(N-X)}(E_{{\sigma}(M-N)}-E_{{\sigma}(M-X)})$ and inhibitory activity coefficient, logIA.

• Journal of Korea Port Economic Association
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• v.27 no.4
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• pp.13-35
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• 2011

The advancement of the information technology provides a wide range of corporate to cope with new business environments that are different in size, life and operation conditions. The Research methodology used in this study is Technology Acceptance Model. The Study Method are mainly survey and questionnaire. The major result of article can be summarized. Its are as the follows: This paper ware investigated the determinants of 'port service quality', 'perceived usefulness', 'perceived ease of use', 'utilization intention', 'practice use'. There are 400 sended samples and 150 returns, 173 of them are analyzed on a port utilization using TAM model. 1. The Port service quality are found to have a positive effect to 'perceived usefulness', 'perceived ease of use', 'utilization intention' 2. The perceived ease of use are found to have a positive effect to 'perceived usefulness', 'utilization intention' 3. The perceived usefulness is found to be positively related to 'utilization intention' 4. The utilization intention is found to have a positive effect to ''practice use' we hove to provide useful contribution to increase the Korea ports' competitiveness in introduction of port information system. In addition, in order to port development offer some insight in further research.

• Korean Journal of Plant Resources
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• v.15 no.3
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• pp.243-249
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• 2002

This experiment was conducted to find out the effects of livestock excrements application on the growth and yield of leaf, stem and seed in Agrimonia pilosa Ledeb. the results were summarized as follow. In the soil after experiment, P2O5 and K contents were high in order of cattle droping 〈 pig droping 〈 chicken droping treatment. The plant height was increased cattle dropping〈 pig dropping〈 chicken dropping treatment plot. Number of stems was inclined to increase in the plot of 2,000 kg/10a application of chicken dropping and cattle dropping. Number of leaves was also increased 21.8∼51.6% by application 3,000 kg/10a of chicken and cattle dropping, and application 2,000 kg/10a of pig dropping, respectively. Dry weight of aerial part was high in order of 1,000〈 3,000〈 2,000 kg/10a〉control, on occasion 2,000 kg/10a treated, that was highest in the application of chicken dropping. Yield of seeds was also increased to 61％ and 86% at the 2,000 kg/10a plot of pig and chicken dropping, respectively. While yield of seeds was increased 50％ at the 3,000 kg/10a application of cattle dropping. Flowering ratio was 49.1％ in control, 55.6, 58.9 and 68.3% in cattle, pig and chicken dropping with 2,000 kg/10a, respectively, on June 22. Flowering ratio was the highest in the plot of chicken dropping with 2,000 kg/10a.

• Journal of Gifted/Talented Education
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• v.25 no.6
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• pp.857-879
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• 2015

This study investigated the relationships among middle school students' perceptions on the roles of online tutor, their deep learning, achievement, and overall evaluation of learning experiences in the context of inquiry based online gifted mathematics and science learning. For this purpose, 249 middle school students who took online course were surveyed about their perceptions on the degree to which their tutor performed the roles as an online tutor. The students were also asked about the activities which indicate deep learning approaches and overall course experiences such as the level of satisfaction, understanding and engagement in the course. The regression analyses were conducted to examine the relationships of students' perceptions on the roles of online tutor, deep learning, achievement, and overall course experiences. The results first showed that the roles of online tutor which affects students' deep learning approach such as high-order learning, integrative learning, reflective learning were the role as a subject matter and evaluation expert. Among the sub variables of deep learning approach the variable that was related to students' overall achievement was the use of high-order learning strategy. Second, the achievement in inquiry task was related to the role of tutor as a guide of learning process and method. Third, students' overall course evaluations such as the level of satisfaction, understanding and engagement were not related to any role of tutor.

• Journal of Preventive Medicine and Public Health
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• v.24 no.2 s.34
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• pp.221-231
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• 1991

A case-control study was conducted to investigate the risk factors (Part of job, Obesity, Alcohol, Smoking, Milk, Salt. and Family history) for hypertension. We selected 330 hypertension cases (male;247, female;83) and 1,336 controls (male;887, female;449) from employees in Taegu city from 1 May to 30 November, 1908. Data was analysed using a logistic regression model. Statistically significant elevated odds ratio were noted for alcohol (odds ratio=3.23), obesity (odds ratio=2.31), salt(odds ratio=1.75) in male (p<0.05) and those in female were noted for alcohol (odds ratio=16.49), family history(odds ratio=3.70), obesity (odds ratio=1.74) and salt (odds ratio=1.73) (p<0.05). Statistically significant reduced odds ratio was noted for milk in both sexes (odds ratio=0.69 for male and 0.65 for female)(p<0.05) and the dose-response relationship between milk intake and hypertension was confirmed (p<0.05). Therefore, milk seems to be preventive factor for hypertension. Smoking was not significantly associated with hypertension in both sexes. The part of job was significantly associated with hypertension in female by simple analysis (P<0.05) but the relationship was disappeared when multivariate analysis (logistic regression analysis) was done.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.6
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• pp.892-898
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• 2005

The effect of gamma irradiation on volatile components of Korean dried ginger (Zingiber officinale Roscoe) was studied and compared with non-irradiated sample. Volatile compounds from non- and irradiated samples were extracted using simultaneous distillation-extraction (SDE) apparatus and analyzed by gas chromatography-mass spectrometer (GC/MS). A total of 83 and 71 compounds were identified and quantified from non-and irradiated dried ginger at dose of 10 kGy. Identified components were hydrocarbons, alcohols, aldehydes, esters, ketones and miscellaneous compounds. The terpenoid compounds in volatile flavor compounds identified from non and irradiatied dried ginger were $98.27\%\;and\;98.12\%$, respectively. $\alpha$ -zingiberene,$\beta$-sesquiphelland reno, geranial, (Z,E) $\alpha$ -farnesene, $\beta$ -phellandene were detected as major volatile compounds of two experimental sample. The amount of volatile components in the samples was changed by irradiation but the profile of volatiles in non- and irradiated dried ginger were the same.

• Journal of the Korean Data and Information Science Society
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• v.28 no.4
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• pp.831-841
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• 2017

The irrational number ${\pi}$ is defined as the ratio of circumference of a circle to its radius and always becomes constant. This article does Monte Carlo approximation of its value using the famous Buffon's needle experiment and shows that its convergence is not always proportional to the sample size. We also do Monte Carlo simulations to see the convergence of the computed ${\pi}$ values from the random walk series with independent normal increment. Finally we apply the theoretical derivation to various financial time series data such as KOSPI, stock prices of Korean big firms, global stock indices and major foreign exchange rates. The historical data shows that log transformed data random walk process but most of their first lagged data don't follow a normal distribution. More importantly the computed value from the ratio of the regression coefficient ${\pi}$ tend to converge a constant, unfortunately not ${\pi}$. Using this result we could doubt on the efficient market hypothesis, and relate the degree of the hypothesis with the amount of deviation of the estimated ${\pi}$ values.

• Korean Journal of Environmental Agriculture
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• v.6 no.1
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• pp.50-60
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• 1987

Sensitivity, expressed in the $96h-LC_{50}$ determined with continuous flow system, was compared for eight developmental stages of Oryzias latipes with butachlor, diazinon and fenitrothion. Significance of the laboratory determined $96h-LC_{50}$ in real field situation was evaluated for butachlor using outdoor model agrosystem. In the laboratory tests, the most sensitive stage was post-larva stage IV(7 days after hatching) with $96h-LC_{50}$ of 0.14, 1.4, and 1.6ppm for butachlor, diazinon and fenitrothion, respectively, whereas the least sensitive stage was early embryo stage(1 day after fertilization), and then the susceptibility was somewhat stable after 21days after hatching. In the model agrosystem test, the highest concentration of 0.53ppm of butachlor in water was obtained at the 2nd day after application. The stages IV and VIII showed mortality of over 50% at 96 hours after application. It is concluded that the conventional use of butachlor in the field would cause significant adverse effect on O. latipes. It is suggested that sensitivity test at the early life stages with fish is an important part of the ecotoxicological assessment of chemicals.