• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.65-73
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• 2015

The hydrofluoric acid (HF) leakage accident occurred on September 2012 in Gumi, Korea affected the surrounding soils and plants. In this study, we investigated fluoride migration in Gumi area through geochemical properties of soil-liquid phase (pore water F and water-soluble F). The concentrations of porewater F and water-soluble F were obtained from N.D (Not detected) to 9.79 mg/L and from 0.001 to 21.4 mg/L, respectively. F in pore water seemed to be affected by artificial and natural origin, and PHREEQC results implied that fluorite is F control factor. F concentrations of soil and soil-liquid phase did not exceed concern level of regulatory criteria and showed similar trends compared by previous studies. Therefore, F contents remained in the soil and soil-liquid phase were considered to be not affected by HF leakage accident.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.75-80
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• 2003

The structures and complexation energies of penta-O-alkylated 1b and penta-O-tert-butyl ester 1e of p-tert-butylcalix[5]arene and their simplified structures (2b and 2e) toward a series of alkyl ammonium guests have been calculated by a semi-empirical AM1 method. For AM1 calculations, complexation efficiencies of the simplified host 2e are very similar to the values of host 1e. The complexes of simplified host 2e with alkyl ammonium ions also have been optimized by ab initio HF/6-31G method. The calculated complexation efficiencies for 2e by ab initio method have been found to be bigger in magnitude than the values obtained by AM1 calculations for linear alkyl ammonium guests. Calculation results show that all of the calix[5]aryl derivatives investigated in this study have much better complexation ability toward ammonium cation without alkyl group compared with other alkyl ammonium guests. Ab initio calculations also well duplicate the molecular discriminating behaviors of calix[5]arene derivative 2e between butyl ammonium ions: $n-BuNH_3^+\;>\;iso-BuNH_3^+\;>\;sec-BuNH_3^+\;>\;tert-BuNH_3^+$.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.34-35
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• 2006

Transparent ZnO thin film transistor (TFT) is fabricated on the glass substrates. The device consists of a high mobility intrinsic ZnO as a semiconductor active channel, Ga doped ZnO (GZO) as an electrode, $HfO_2$ as a gate insulator. GZO and $HfO_2$ layers are prepared by using a pulsed laser deposition and intrinsic ZnO layers are fabricated by using an rf-magnetron sputtering, respectively. The transparent TFT is highly transparent (> 87 %) and exhibits n-channel, enhancement mode behavior with a field-effect mobility as large as $11.7\;cm^2/Vs$ and a drain current on-to-off ratio of about $10^5$.

• Korean Journal of Medicinal Crop Science
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• v.23 no.4
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• pp.324-333
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• 2015

Lepisorus thunbergianus (Kaulf.) Ching has been used in folk medicine in Korea. In this study, a L. thunbergianus methanol extract and its fractions were investigated for their antioxidant properties. The results showed that the ethyl acetate and butanol fractions of L. thunbergianus possess potent DPPH radical scavenging activities. Both fractions also possessed reducing power and inhibited reactive oxygen species formation. In addition, the cytotoxic activity of the L. thunbergianus n-hexane fraction (HF) was investigated. The results suggested that the HF remarkably suppressed proliferation of human breast, liver and colon cancer cells. These results demonstrate, for the first time, that L. thunbergianus extract induces apoptosis in SW620 cells, suggesting that L. thunbergianus may have potential as a therapeutic agent for colon cancer.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1919-1921
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• 1999

AlN thin films were fabricated by sputter for the application of MIS device with Al/AlN/Si structure. We controled that sub-temperature room-temperature. Sputtering pressure 5 mTorr, flow ratio Ar:$N_2$=1:1(4sccm:4sccm), and appended hydrogen gas $0{\sim}5%$. AlN thin films thickness fabricated to maintain $2700{\AA}$ time control. Before the experiment remove to the contaminated material use the Ultrasonic every 10 minute use the acetone and ethanol, then use the HF remove oxide-substance at 10 second. To analyze characteristic of the $H_2$ gas addition period, C-V and I-V characteristic make and experiment $H_2$ gas at addition period progressive capability of I-V and C-V characteristic.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.2
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• pp.78-83
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• 2007

CrN coatings were deposited by cathodic arc ion plating method on the SKD11 steel substrates. Atmosphere temperature of $350^{\circ}C$, arc current of 90 A, nitrogen partial pressure of 1.0-5.3 Pa, and negative bias voltage of 30-135 V were selected. The characteristics of microstructure were investigated with XRD. Hardness, adhesion and friction coefficient measured by microhardness tester, scratch tester, and ball on disk tribometer. Microstructures depended on nitrogen partial pressure and bias voltage. The preferred orientation of the films was changed from (200) to (111) with decreasing pressure and increasing bias voltage. Adhesion properties related with microstructure, but microstructure changes slightly influenced on hardness and friction properties. The critical load.($Lc_1$) and hardness of CrN films deposited at 5.3 Pa, -30 V condition were 55 N(HF1), $2157{\pm}47\;Hk_{0.025}$. The friction coefficient were about 0.5 under dry condition.

• Korean Journal of Materials Research
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• v.17 no.5
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• pp.273-277
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• 2007

Vertically aligned Zinc Oxide rod arrays were grown by the self-assembly hydrothermal process on the GaN epitaxial layer which has a same lattice structure with ZnO. Zinc nitrate and DETA solutions are used in the hydrothermal process. The $(HfO_2)$ thin film was deposited on GaN and the patterning was made by the photolithography technique. The selective growth of ZnO rod was achieved with the patterned GaN substrate. The fabricated ZnO rods are single crystal, and have grown along hexagonal c-axis direction of (002) which is the same growth orientation of GaN epitaxial layer. The density and the size of ZnO rod can be controlled by the pattern. The optical property of ordered array of vertical ZnO rods will be discussed in the present work.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.12-12
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• 2000

This paper investigated the effect of the film deposition rate for $CrN_x$ microstructure and mechanical properties. For these purpose, pure Cr an stoichiometric CrN films were deposited with various target power density on Si hardened M2 tool steel. The variation of ni trogen concentration in $CrN_x$ f analyzed by AES and deposition rate was calculated by measuring of thickness using ${\alpha}-step$ profilometer. The microstructure was analyzed by X-Ray Diffract and Scanning Electron Microscopy(SEM), and mechanical properties were evalua residual stress, microhardness and adhesion tests. Deposition rate of Cr and CrN increased as an almost linear function of target power density from $0.25\mu\textrm{m}/min$ and $0.15\mu\textrm{m}/min$ to $0.43\mu\textrm{m}/min$. Residual stresses of Cr and CrN films were from tensi Ie to compressive stress with an increase of deposi tion rate a compressive stresses were increased as more augmentation of deposition r maximum hardness value of $2300kg/\textrm{mm}^2$ and the best adhesion strength correspond HF 1 were obtained for CrN film synthesized at the highest target densitY($13.2W/\textrm{mm}^2$) owing to high residual compressive stress and increasing mobility.

• Analytical Science and Technology
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• v.20 no.3
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• pp.219-226
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• 2007

Glass is frequently encountered as types of materials that are submitted to forensic science laboratories as a result of trace evidence transfers. The repeatability and the reproducibility of trace element analysis were presented. An analysis of variance (ANOVA) was performed on laser ablation inductively coupled plasma spectrometric analyses of the fragments to identify the source. Pairwise comparisons were completed for all samples. In a pairwise comparison, each sample was compared to each other for a possible [n(n-1)/2] (n : numbers of the samples) total comparison to associate/discriminate samples using Tukey's HSD method. The aim of this study was to determine the utility of LA-ICP-MS for multi-element analysis of forensic samples. The 12 glass fragments from two manufacturers were collected and analyzed to identify the source. An analysis of variance (ANOVA) was performed on 31 elements in NIST 612 Trace elements in Glass. Elements were classified into four categories defined by the combination of precision and variation of inter-samples. We selected 11 elements, 209Bi, 90Zr, 121Sb, 178Hf, 59Co, 238U, 208Pb, 140Ce, 118Sn, 49Ti and 137Ba. 6 pairs out of 66 possible pairs were not distinguished when compared by 137Ba (p<0.05). However, all samples were distinguished using both 49Ti and 137Ba (p<0.05). In conclusion, multi-elemental analysis with LA-ICP-MS is a potential tecnique for the discrimination of forensic samples.

• Journal of Korean Biological Nursing Science
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• v.16 no.4
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• pp.334-341
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• 2014

Purpose: The purpose of this study was to examine the effects of aroma-necklace application on perceived stress, symptoms of stress and changes in autonomic nervous system among nursing students in clinical training. Methods: A research design for this study was a non-equivalent control group, non-synchronized pre-post test. The experimental group (n=39) underwent aroma inhalation by necklace which contains an essential oil mixture of lavender and sweet orange mixture in ratio of 2:1 for 2 weeks while the control group (n=36) received placebo therapy. The data were collected using self-administered questionnaires and measurement of heart rate variability (HRV) and analyzed using the PASW 18.0 program. Results: The perceived stress scores and scores of peripheral manifestations in the experimental group were significantly lower than those of the control group. All indices of HRV were significantly different between the two groups. LF norm and LF/HF ratio in the experimental group were significantly lower than those of the control group, and HF norm in the experimental group was significantly higher than that in the control group. Conclusion: It can be suggested that aroma-necklace application was effective in decreasing perceived stress and peripheral manifestations of stress and in changing HRV indices among nursing students in clinical training.