• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.5-8
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• 2009

MgO nanodots have been deposited and formed on top of the substrate surface. Mg was sputtered to form the MgO nanodots on the single crystal substrates by rf-sputtering method and followed by heat treatment in the oxygen ambient. The deposition and formation of MgO nanodots have been controlled systematically using the process variables such as substrate temperature, sputtering time, and rf-power. As the substrate temperature increased from the room temperature the density of MgO nanodots decreased. The optimal conditions of MgO nanodots formation using the rf-sputtering was investigated and the maximum density of more than $230/{\mu}m^2$ on single crystal substrates was obtained when the rf-power of 100 watts was applied for 30 seconds at room temperature. The typical size of MgO nanodots was identified to be <160 nm(diameter) and 4-30nm (height) by atomic force microscopy. The modulated surface morphology was examined through surface images and cross-section analysis and discussed for the artificial pinning sites in the superconducting films.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.105-112
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• 2008

Disinfection is a basic and effective microorganism inactivation method and historically contributed a decrease in waterborne diseases. To guarantee the disinfection ability, improving T in CT value is important. Many indexes are used to estimate the hydraulic efficiency, however, these are black-box analysis. Therefore it is need to develope new estimation method. In this study, internal short-circuiting estimation method (ISEM) is developed using CFD and we inquire into the factor which causes increase of $T_{10}/T$ value as LW ratio increases. And the effect of shape on the relation of LW ratio and $T_{10}/T$ is analyzed. As LW ratio increases, internal short-circuiting index (ISI) of influent and effluent zone is rapidly reduced and recirculation and dead zone are reduced in channel zone. Therefore, as the $T_{10}/T$ value converges maximum value, ISI curve is changed from "V" shape to "U" shape and hydraulic efficiency is improved especially in downstream portion of clearwell. The less the shape ratio(width/length of clearwell) is the less the $T_{10}/T$ value is at a same LW ratio because the portion of turning zone increases as shape ration decreases, therefore more boundary separation is generated.

• Research in Plant Disease
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• v.8 no.4
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• pp.207-214
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• 2002

Tobacco rattle virus(TRV) was detected from Gladiolus hybridus, Crocus spp. and Narcissus spp. leaves show-ing notched or stripe on the leaf and malformation symptoms collected from Daegu and Kyungbuk province by electron microscopy (EM), immunosorbent electron microscopy (ISEM) and host range study. Direct negative staining method by EM showed rigid rod long particles 170~200$\times$22 nm and rigid rod short particles 40~114$\times$22 m. TRV-K isolated from G. hybridus propagated with Nicotiana tabacum. TRV coat protein(CP) gene was amplified using specific oligonucleotide primer by RT-PCR. Sequence analysis of amplified CP gene showed 99.5％ nucleotide similarity to TRV-ORY.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.5-8
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• 2007

All three buffer layers of $Y_2O_3$, YSZ, and $CeO_2$ have been deposited on the biaxially textured metal substrates using rf-sputtering method, The first 50-70nm thick $Y_2O_3$ films were grown epitaxially on biaxially textured metal substrates as a seed layer and followed by the diffusion barrier ${\sim}100nm$ thick YSZ and subsequent capping layer ${\sim}200nm$ thick $CeO_2$ deposited epitaxially on top of $Y_2O_3$ seed layer. The epitaxial orientation of all three layers were all (100) grown with rocking curve Full Width at Half Maximum(FWHM) of $4-5^{\circ}$ and in plane phi-scan FWHM of $6-8^{\circ}$ using X -ray diffraction analysis. The NiO phases formed during the $Y_2O_3$ seed layer deposition seem to degrade the crystallinity and roughen the surface morphology of the following layer observed by AFM(Atomic Force Microscopy). The buffered tapes were used as substrates for long length YBCO coated conductors with high critical current density $J_c$. The five multi-turn of metal tapes was employed to increase the thickness of films and production rate to compensate the low growth rate of rf-sputtering method.

• Journal of Powder Materials
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• v.10 no.1
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• pp.21-25
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• 2003

The Sn - graphite composites were prepared by chemical encapsulation method for anode materials in Li-ion batteries. EDS and XRD analysis confirmed the presence of Sn in the graphite structure. Cyclic voltammometry (CV) measurement shows extra reduction and oxidation peaks, which might to be related to the formations of $Li_xSn$ alloy compounds. Graphite-tin composite electrodes demonstrated higher Lithium storage capacities than graphite electrodes. Due to the nature of fine Sn particles on graphite surface, the graphite-tin composite electrodes have shown a good cycle properties.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1240-1242
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• 2005

In this study, we estimate the transport current loss of Bi-2223/Ag tapes with non-uniform current distribution. The conductor was consisted of three Bi-2223/Ag tapes and the each tapes were attached in parallel. The loss of conductor was investigated both numerical and experimental methods. The numerical code to predict ac loss was developed, and finite element method was introduced. It contained intrinsic properties of superconducting tape, which was obtained from nonlinear current voltage relation with external magnetic field and its orientation. Two results were compared and discussed. They showed good agreements with each other.

• Research in Plant Disease
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• v.9 no.3
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• pp.107-115
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• 2003

Chinese yam (Dioscorea opposita cv. Jang-Ma) plants showing necrotic mosaic symptom were collected from their growing fields in Andong, Euisong, Gunwi and Daegu, Korea. Direct negative stainning method by electron microscope showed filamentous particles of about 660 nm in length. Immunosorbent electron microscopy (ISEM) revealed filamentous particles of 660nm decorated with antiserum of Chinese yam necrotic mosaic virus (ChYNMV). The virues purified partially were used to isolate viral RNA as template for RT-PCR to amplify about 1.2 kbp of 3'-terminal region (coat protein, 3'-UTR) with ChYNMV specific and oligo-dT primers. Amino acids sequences of amplified CP genes revealed that the viruses shared 97.9% similarity with ChYNMV (AB044386) wh ich was known as the member of Macluravirus. So the viruses from Chinese yam (D. opposita cv. Jang-Ma) plants were identified as ChYNMV. Comparing the CP amion acid sequences of ChYNMV strains with other macluraviruses such as Cardamon mosaic virus (CdMV), Narcissus latent virus (NLV) and Maclura mosaic virus (MacMV) revealed that N-terminal was the most varialbe region and conserved regions were present within the genus Macluravirus.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3033-3038
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• 2012

The hydrogen storage mechanism of graphite was studied by measuring the electrical resistance change. Graphite was expanded and activated to allow for an easy hydrogen molecule approach and to enlarge the adsorption sites. A vanadium catalyst was simultaneously introduced on the graphite during the activation process. The hydrogen storage increased due to the effects of expansion, activation, and the catalyst. In addition, the electrical resistance of the prepared samples was measured during hydrogen molecule adsorption to investigate the hydrogen adsorption mechanism. It was found that the electrical resistance changed as a result of the easy hydrogen molecule approach, as well as of the adsorption process and the catalyst. It was also notable that the catalyst improved not only the hydrogen storage capacity but also the speed of hydrogen storage based on the response time. The hydrogen storage mechanism is suggested based on the effects of expansion, activation, and the catalyst.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.4
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• pp.167-172
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• 2017

In this study, high performance patching repair mortars with light weight and sulfuric acid resistance properties were suggested. Their performance estimation were investigated based on KS F 4042 using patching repair mortar with light weight aggregate and soluble polymer of Type I and sulfuric acid resistance mortar of Type II, From these results, it was confirmed that these motors were satisficed and improved by all standard tests of KS F 4042.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.4
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• pp.173-177
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• 2017

A polynaphthalenesulfonate (PNS) superplasticizer and its relation to the fluidity of cement paste (w/c = 0.35) has been investigated for three cements at a given dosage of PNS superplasticizer. Chemical properties of three cements were characterized with a XRD, XRF. The additive effects of $Na_2SO_4$ on the fresh concrete with w/c = 0.33 were also estimated by the measurement of compressive strength, slump, air content. The experimental results exhibited that the addition of sodium sulfate 2.6 % to the cement A and C improves slump loss. In case of cement E, the addition of sodium sulfate 1.3 % was effective.