• Journal of applied mathematics & informatics
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• v.32 no.3_4
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• pp.503-509
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• 2014

For a connected graph G, there are orientations of G have different hull numbers, geodetic numbers, and convexity numbers. The lower orientable hull number $h^-(G)$ is defined as the minimum hull number among all the orientations of G and the upper orientable hull number $h^+(G)$ as the maximum hull number among all the orientations of G. The lower and upper orientable geodetic numbers $g^-(G)$ and $g^+(G)$ are defined similarily. In this paper, We investigate characterizations of the orientable numbers and the conditions that the relation $h^-(G){\leq}g^-(G)$ < $h^+(G){\leq}g^+(G)$ holds.

• Bulletin of the Korean Mathematical Society
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• v.47 no.5
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• pp.1025-1036
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• 2010

A new class of generalized open sets in a topological space, called e-open sets, is introduced and some properties are obtained by Ekici [6]. This class is contained in the class of $\delta$-semi-preopen (or $\delta-\beta$-open) sets and weaker than both $\delta$-semiopen sets and $\delta$-preopen sets. In order to investigate some different properties we introduce two strong form of e-open sets called e-regular sets and e-$\theta$-open sets. By means of e-$\theta$-open sets we also introduce a new class of functions called strongly $\theta$-e-continuous functions which is a generalization of $\theta$-precontinuous functions. Some characterizations concerning strongly $\theta$-e-continuous functions are obtained.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.507-512
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• 1998

Molecular analysis has been done for characterization of the interactions between three beet curly top virus (BCTV) strains and two Arabidopsis ecotypes in terms of virus inducible disease symptoms and infectivities. The total DNA was isolated from three tissues (shoot tips, infection origins and roots) of virus infected plants and this DNA was analyzed by quantitatively and qualitatively to elucidate virus movement and symptom development. CTV-Worland infected Col-O and Sei-O showed only symptom shown in hypersusceptible ecotype Sei-O by BCTV-worland was shoot tip stunting. Kinetics of virus DNA accumulation of three different viruses indicated that roots contained more virus DNA than shoot tips or infection origins, and that disease symptom severity was strongly correlated with virus DNA accumulation. These results suggest that the mild and Worland-specific symptoms shown in Sei-O by BCTV-worland are caused by the interactions of host factors provided by hypersusceptible ecotype and viral factors of mild strain.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.72-77
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• 2007

This study deals with characterizations of microstructure and wear performance of a cladding layer, product on 1.9 mm-thick mild steel plate by the electric resistance welding, of composite metal powder of Coarse WC-6.5%Co and high carbon alloy (SHA). The cladding layer was examined and tested for microstructural features, chemical composition, hardness, and bondability. The cladding layer have two different matrix were observed by an optical microscope and EPMA. The one was the coarse WC-6.5Co structure. The other was the melted SHA with surrounding the WC-6.5Co structure. The hardness of WC-6.5Co was 1210HV. The hardness of SHA was 640HV.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3740-3744
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• 2012

We synthesized three different derivatives of bis-spiropyran using simple organic reactions with high yields. BSP1, a derivative of bis-spiropyran having a connection at the position 6' and BSP2, a derivative of bis-spiropyran having a connection at the position 5 and BSP3, a derivative of bis-spiropyran containing a dithienylethene group between two spiropyran moieties were synthesized. The optical properties of BSPs were characterized. UV-Vis spectra showed that BSPs exhibit reversible photo-isomerization and the efficiency of photo-isomerization is highly dependent on the position of nitro group. BSPs having nitro group at para position of hydroxy group showed the higher efficiency of photo-isomerization that the one having nitro group at ortho position. The optical microscope images obtained under ultraviolet or visible light exposure demonstrated that the formation of nanorods can be reversibly controlled by optical signal.

• Carbon letters
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• v.16 no.1
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• pp.51-56
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• 2015

Carbonate-type organic electrolytes were prepared using propylene carbonate (PC) and dimethyl carbonate (DMC) as a solvent, quaternary ammonium salts, and by adding different contents of 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMImBF_4$). Cyclic voltammetry and linear sweep voltammetry were performed to analyze conducting behaviors. The surface characterizations were analyzed by scanning electron microscopy method and X-ray photoelectron spectroscopy. From the experimental results, increasing the $EMImBF_4$ content increased the ionic conductivity and reduced bulk resistance and interfacial resistance. In particular, after adding 15 vol% $EMImBF_4$ in 0.2 M $SBPBF_4$ PC/DMC electrolyte, the organic electrolyte showed superior capacitance and interfacial resistance. However, when $EMImBF_4$ content exceeded 15 vol%, the capacitance was saturated and the voltage range decreased.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.17-27
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• 2016

In the high-frequency characterizations of planar circuit components, measurement data may not be physical. It is mainly due to resonance effects concerned with discontinuities which are inevitable for a planar component characterization. In this paper, a novel accurate transmission line characterization method is presented that excludes the resonance effects based on measurement data reconfirmation. For the physically obvious data acquisition near the resonance frequencies of a transmission line, the additional lines with different line lengths are fabricated on the same substrate. The test transmission lines are characterized by using vector network analyzer (VNA) in 100 MHz to 26.5 GHz. It is shown that an accurate transmission line characterization can be achieved with the proposed measurement data reconfirmation technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.63-66
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• 1999

The effects of UV and ozone on the weathershed materials for 5 polymer insulators were investigated. This study was carried by material characterizations such as surface microstructure, thermal property, chemical structure and contact angle. The aged specimens are compared with new ones. In case of UV, the chalking of fillers and cracking of surface were increased with the increase of UV radiation time. In case of ozone, aged specimens are not different from new ones. From this study, It can be concluded that UV has more effect on the surface properties of weathershed materials than ozone.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.455-460
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• 2018

Chromium plating is a common surface treatment technique extensively applied in industry due its excellent properties which include substantial hardness, abrasion resistance, corrosion resistance, surface color, and luster. In this study, the effect of PTFE on corrosion behavior of Cr-P plating, low carbon steel substrates are electroplated in Cr(III) baths without and with PTFE. Trivalent chromium carbon plating was electroplated from trivalent chromium sulfate-based baths with different PTFE dispersion contents. The study focused on the microstructure, PTFE content, roughness, and corrosion resistance of the Cr-P-PTFE composite plating. Scanning electron microscopy and atomic force microscopy images showed a smoother plating and a decrease in the surface roughness of the electrodeposited. The results demonstrate that PTFE eliminates the cracks within plating by reducing internal stress. Therefore, the corrosion resistance of Cr-P-PTFE composite platings were better than that of Cr-P alloy platings.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.65-66
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• 2023

This study is aimed to understand the effect of pyrolysis temperature on the biochar synthesis for shape stabilizing the Lauric acid (LA). Three different temperatures (350, 500, and 650 ℃) have been chosen with a soaking time of 1h for synthesizing biochars form sesame plants (SP). The structural characterizations indicate the formation of amorphous biochar at 350 ℃ whereas, a stain of graphene formation has been observed for the biochar synthesized at 500 ℃. Formation of a substantial amount of graphene has been found for the sample, synthesized at 650 ℃. Energy storage performances of the PCMs which are shape stabilized by these three biochars have been discussed in this paper.