• Carbon letters
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• v.12 no.4
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• pp.207-217
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• 2011

We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.2
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• pp.73-79
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• 1996

This study was conducted to investigate the faunal composition and distribution patterns of macrobenthic community in the deep sea sediments of the KODOS area, the northeastern Pacific Ocean during May 1996. Benthic animals were collected at 25 stations using a spade type box corer. Sediments were sieved through -.3 mm mesh screen. A total of 17 faunal groups in 9 phyla and 363 specimens were identified. Nematoda was the most abundant faunal group which accounted for 30.0% of total abundance. Other dominant faunal groups were foraminiferans (25.1%), harpacticoids (10.2%), xenophyophores (5.2%), and polychaetes (4.7%), Polychaeta was a typically dominant component of macrobenthic community in the study area except traditionally recognized meiofauna taxa. Mean occurrence number of faunal taxa was ca. 6 per 0.01 m$\^$2/, and mean density was estimated as 1,288 indiv./m$\^$2/. The abundance of whole fauna and that of each faunal group was highest at the surface layer of sediment, and decreased monotonously along the sediment depth; 98% of faunal abundance was found within 10 cm depth layer.

• Journal of The Korean Association of Information Education
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• v.8 no.1
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• pp.27-35
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• 2004

In Web-based instruction, learners are the subjects. learners differently accept web-based instruction that educational experts and system developers should think effectively that. This study was researched evaluation criteria that learners should think web-based instruction successively. research method process was following. driving 35 criteria in literary review about effectiveness web-bases instruction strategies and the questionnaire was marked up by learners and the questionnaire was conducted by factor analysis, driving 4 factors 28 criteria. By study findings learners think important component for effective web-based instruction to instructional strategis, system facility, tutor to help learning course, screen design. finally, for impletation effective web-based instruction consider implementation process by ISD.

• Progress in Medical Physics
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• v.10 no.1
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• pp.47-54
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• 1999

Purpose: To verify the BRW coordinates of target located within the limit of XKnife hardware, and to verify the successful transfer of image data, rod detection, anatomical structure when CT images are transferred into a XKnife computer. Materials and Methods: Target coordinates of 13 patients were calculated by SCS1 computer through the rod image on the console screen and film. BRW coordinates of target and landmark calculated by SCS1 computer were compared to those acquired by XKnife localizer. Results : Vertical components of BRW coordinates of target for 13 patients are larger than -50 mm, and then the vertical components of BRW coordinates of target are localized within the limit of XKnife hardware. Average differences between XKnife and SCS1 for BRW coordinates of target and landmark were within 1 mm for AP and LAT components, 0.5 mm for VERT component. Conclusion : It was verified that the SCS1 computer is adequate tool to calculate BRW coordinates of target quickly. And by the comparison between SCS1 computer and XKnife localizer, it was verified that the image transfer into the XKnife computer was performed successfully.

• The Korean Journal of Mycology
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• v.14 no.4
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• pp.265-271
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• 1986

To screen biologically active components of the higher fungi of Korea, the dried carpophores of Auricularia polytricha were extracted with water. The extract was examined for acute toxicity in ICR mice. A low molecular weight toxin of this fungus was purified by a acetone precipitation followed by cellulose, silica gel and Sephadex LH-20 column chromatography. Major symptoms of this toxin were decreasing of normal motility, eye extrusion, hair erection, shivering, trembling of head, paralysis, rapid running or moving before death and depression of respiration. The median lethal doses of the total extract were 1. 28 g/kg and 4. 31 g/kg by i.p. and p.o. administrations, respectively. The amounts of one mouse lethal unit of the total extract and final fraction that killed a 20 g mouse within 30 minutes were 28.5 and 12.0 mg/mouse, respectively.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.16-21
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• 2008

The key component of a direct methanol fuel cell (DMFC) is the membrane electrode assembly (MEA), which comprises a polymer electrolyte membrane and catalyst layers (anode and cathode electrode). Generally the catalyst layer is coated on the porous electrode supporter (e.g. carbon paper or cloth) using various coating methods such as brushing, decal transfer, spray coating and screen printing methods. However, these methods were disadvantageous in terms of the uniformity of catalyst layer thickness, catalyst loss, and coating time. In this work, we used bar-coating method which can prepare the catalyst layer with uniform thickness for MEA of DMFC. The surface and cross-section morphologies of the catalyst layers were observed by SEM. The performances and resistance of the MEAs were investigated through a single cell evaluation and impedance analyzer.

• The Journal of Korean Society of Virology
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• v.27 no.1
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• pp.87-95
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• 1997

Methanol and/or boiling water extraction of 201 natural products and subsequent MTT assay using MT-4 cell line was carried out to screen the anti-HIV-1 activity. Among 97 methanol extracts, 7 extracts from Chrysanthemi Indicium Flos, Magnoliae Cortex, Machili Cortex, Reynoutriae Rhizoma, Lithospermi Radix, Agastachis Herba, and Chaenomelis Fructus showed anti-HIV-1 activity and their SI value were 2.25 to 5.77. In addition, among 119 boiling water extracts, 10 extracts from Lonicerae Caulis et Foloium, Elsholtziae Herba, Leonuri Herba, Portulacae Herba, Schizonepetae Herba, Curcumae Rhizoma, Amomi Cardamomi Fructus, Cirsii Radix et Herba, Carpesii Herba, and Siegesbeckiae Herba showed anti-HIV-1 activity and their SI value were 1.30 to 7.64. Methanol extracts of above seven natural products were fractionated and the anti-HIV-1 activity of each fraction was examined. Extraction was carried out with hexane, chloroform, butanol, and water to trace active anti-HIV-1 componets. As a result, the water fraction of Magnoliae Cortex, Machili Cortex, Reynoutriae Rhizoma, Agastachis Herba, Chaenomelis Fructus and the butanol fraction of Chrysanthemi Indicium Flos, Reynoutriae Rhizoma showed anti-HIV-1 activity and their SI value were 1.40 to 8.02. We could reach a conclusion that studies to trace the anti-HIV-1 active component of each natural products in further fractionation and to identify its structure by Infrared spectroscopy, NMR spectroscopy and gel permeation chromatography were needed.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.3
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• pp.150-155
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• 2010

Generally, plasma nitriding process has composed with a nitriding layer within glow discharge region occurred by energy exchange. The dissociations of nitrogen molecules are very difficult to make neutral atoms or ionic nitrogen species via glow discharge area. However, the captured electrons in which a double-folded screen with same potential cathode can stimulate and come out some single atoms or activated ionic species. It was showed an important thing that is called "hat is a dominant component in this nitriding process?" in plasma nitriding process and it can take an effective species for without compound layer. During a plasma nitriding process, it was able to estimate with analyzing and identification by optical emission spectroscopy (OES) study. And then we can make comparative studies on the nitrogen transfer with plasma nitriding and ATONA process using plasma diagnosis and metallurgical observation. From these observations, we can understand role of active species of nitrogen, like N, $N^+$, ${N_2}^+$, ${N_2}^*$ and $NH_x$-radical, in bulk plasma of each process. And the same time, during DC plasma nitriding and other processes, the species of FeN atom or any ionic nitride species were not detected by OES analyzing.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.45-48
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• 1984

Ion-pair reverse phase HPLC techniques were used to compare the contents of IAA and IAAsp in the embryogenic and non-embryogenic calli derived from ginseng (Panax ginseng C.A. Meyer) root tissues. The contents of IAA and IAAsp of the embryogenic callus were much higher (7 to 18 X respectively) than those of non-embryogenic callus. There is a distinct fluorescent peak of an unknown component in the HPLC profile of the extract for indolic compounds from non-embryo-genic callus. This distinct difference may be employed as a promising parameter to screen the culture pieces for obtaining the calli with high potential for embryoid formation.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.390-394
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• 2003

In the post-genome period, the technique for identifying gene expression has been progressed to high throughput screening. In the field of molecular nutrition, the use of screening techniques to clarify molecular function of specific nutrients would be very advantageous. In this study, we have evaluated Zn-regulated gene expression in Zn-deficient, homocystein-treated EA.hy926 cells, using cDNA microarray, which can be used to screen the expression of many genes simultaneously. The information obtained can be used for preliminary assessment of molecular and signaling events modulated by Zn under pro-atherogenic conditions. EA.hy926 cells derived from human umbilical vein endothelial cells were cultured in Zn-adequate (control, 15 $\mu$M Zn) or Zn-deficient (experimental, 0 $\mu$M Zn) Dulbecco's MEM media under high homocysteine level (100 $\mu$M) for 3 days of post-confluency. Cells were harvested and RNA was extracted. Total RNA was reverse-transcribed and the synthesized cDNA was labeled with Cy3 or Cy5. Fluorescent labeled cDNA probe was applied to microarray slides for hybridization, and the slide was then scanned using a fluorescence scanner. The expression of seven genes was found to be significantly decreased, and one significantly increased, in response to treatment of EA.hy926 cells with Zn-deficient medium, compared with Zn-supplemented medium. The upregulated genes were oncogenes and tumor suppressor genes, cell cycle-related genes and transporter genes. The down-regulated gene was RelB, a component of the NF-kappaB complex of transcription factors. The results of this study imply the effectiveness of cDNA microarray for expression profiling of a singly nutrient deficiency, namely Zn. Furthur study, using tailored-cDNA array and vascular endothelial cell lines, would be beneficial to clarify the molecular function of Zn in atherosclerosis, more in detail.