• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.585-589
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• 2012

The characteristics of interface layer and the effect of mole fraction of inlet gas mixture($B_2H_6/H_2/N_2/TiCl_4$) on the microstructure of Ti(B,N) films were studied by microwave plasma hot filament CVD process. Ti(B,N) films were deposited on a substrate(STD-61) to develop a high performance of resistance wear coating tool. Ti(B,N) films were obtained at a gas pressure of 1 torr, bias voltage of 300 V and substrate temperature of $480^{\circ}C$ in $B_2H_6/H_2/N_2/TiCl_4$gas system. It was found that TiN, $TiB_2$, TiB and hexagonal boron nitride(h-BN) phases exist in thin layer on the STD-61.

• The Korean Journal of Food And Nutrition
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• v.14 no.6
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• pp.579-584
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• 2001

Chitooligosaccharides were prepared by enzymatic hydrolyzing of crab shell chitosan. Low Molecular Meight chitooligosaccharides(LMW-chitooligosaccharides) , 64.3% of which was composed of trimer, tetramer, and pentamer, was obtained by hydrolyzing chitosan with the chitosanase originated Bacillus pumilus BN -262. High Molecular Meight chitooligosaccharides ( HMW-chitooligosaccharides ) , 49.3% of which was composed of chitooligosaccharides over heptamer, was obtained by hydrolyzing chitosan with the cellulase originated Trichoderma viride. Antimicrobial activity and colony forming inhibitory activity of chitooligosaccharides were tested. MIC of LMW-chitooligosaccharides against Bacillus cereus, Bacillus subtilis, Candida albicans, Escherichia coli, Escherichia coli O157 : H7, Lactobacillus plantarum, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Streptococcus mutans was 1.5%, 1.5% above 2.0%, 1.5%, 1.5%, below 0.5%, 2.0%, 1.5%, above 2.0%, 1.0%, 1.5% and 1.0% respectively. .

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.581-585
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• 2012

Machinability is important in engineering applications, especially in the current micro-electronics industry. Most ceramic components have complex shapes and hence require machining generally with diamond tools, which incurs a high production cost. Recently, h-BN-containing machinable ceramics have been developed, but these materials are very expensive due to the high raw materials and production costs. Therefore, the development of low-cost machinable ceramics is necessary. In this study, inexpensive $Al_2TiO_5$ was studied as a replacement for h-BN. $Al_2O_3$, $TiO_2$ and partially stabilized $ZrO_2$(PSZ) powders were mixed with various mole ratios and were sintered at $1500^{\circ}C$ for 1 h. The density, hardness and strength were then measured. The phase analysis and microstructures were observed by XRD and SEM, respectively. The machinability of each specimen was tested by micro-hole machining. The results of this research showed that the produced composites could be used as low-cost machinable ceramics.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.110-117
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• 1995

Tc-99m Labeled hexamethylenepropyleneamineoxime ([$^{99m}Tc$]-HMPAO) is a famous amino-oxime compound and is widely used to construct SPECT images of cerebral blood flow. To investigate the relationship between chemical structure and radiolabeling in these kind of diamine-oxime compounds, we synthesized seven compounds by Schiff's base formation and successive reduction with sodium borohydride. They were (RR/SS )-4,8-diaza-3,6,6,9-tetramethylundecane-2,10-dione bisoxime (2), (RR/SS/meso)-4,8-diaza-3,9-dimethy-lundecane-2,10-dione bisoxime (4), (RR/SS/meso)-4,8-diaza-3,10-dimethyldodecane-2,11-dione bisoxime (5), (RR/SS/meso)-4,7-diaza-3,6,6,8-tetramethyldecane-2,9-dione bisoxime (8), (RR/SS/meso)-4,7-diaza-5,6-cyclohexyl-3,8-dimethyldecane-2,9-dione bisoxime (10), (RR/SS/meso)-3,4-bis(1-aza-2-methyl-3-oxime-1-butyl)-benzoic acid (12), and (RR/SS/ meso)-2,3-bis(1-aza-2-methyl-3-oxime-1-butyl) benzophenone (14). Chemical structures of all the synthesized compounds were identified by taking $^1H$ spectrum. Among them, 2 and 4 are propyleneamine oxime (PnAO), 6 is butyleneamine oxime (BnAO) and 8, 10, 12 and 14 are ethyleneamine oxime (EnAO). Each compound (0.5 mg) was incubated with stannous chloride (0.5 g - 8 g), carbonate-bicarbonate buffer (final concentration = 0.1 M, pH 7 - pH 10) and Tc-99m-pertechenate (1 ml). Tc-99m labeling of these compounds were checked by ITLC (acetone), ITLC (normal saline), reverse phase TLC (50 % acetonitrile) and ITLC (ethyl acetate). According to the results, EnAO's were not labeled by Tc-99m in any of above condition. About 11 % of maximum labeling efficiency was obtained with BnAO. However, 4 (PnAO) was labeled with Tc-99m to 85 % which is similar to the labeling efficiency of 2 (HMPAO). Hydrophilic impurity (9 % ) was the most significant problem with the labeling of 4, however, pertechnetate (3 % ) and colloid (3 %) were minor problem. In conclusion, we synthesized seven diamine blsoxlme compounds. Among them, four EnAO compounds were not labeled by Tc-99m. A BnAO was labeled poorly and two PnAO's were labeled well. These labeling can be explained by tertiary structure of their Tc-99m chelate.

• The Korean Journal of Food And Nutrition
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• v.20 no.4
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• pp.378-383
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• 2007

To study the characteristics and processing of Kochujang which is rapidly fermented by commercial enzymes, three kinds of Kochujang(KP-FA, KP-FN, and KP-BN) using commercial proteases and one Kochujang(KM) using Meju were prepared and their qualities investigated. There were only small differences in pH and acidity between each Kochujang. The moisture contents were high tendency in the three kinds of Kochujangs using the commercial proteases at 20 days of fermentation. Reducing sugars had a tendency to decrease during the fermentation in the Kochujangs using the proteases. During the first half of fermentation, the Kochujangs made with proteases showed higher amino nitrogen contents than the Kochujang(KM) made using Meju. Acidic protease activity was high in KP-FA at 20 days of fermentation and neutral protease activity was high in KP-FN and KP-BN at the beginning of fermentation. The Kochujangs made using the proteases, through 20 days of fermentation, obtained high preference in the sensory evaluation for color, texture, and overall acceptability. However, the hot taste was stronger in these Kochujangs during the fermentation.

• Journal of Powder Materials
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• v.23 no.4
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• pp.276-281
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• 2016

Carbonyl iron (CI) is successfully incorporated as an additive into a polystyrene (PS) matrix via a highenergy ball milling method, under an n-hexane medium with volume fractions between 1% and 5% for electromagnetic interference shielding applications by the combination of magnetic CI and an insulating PS matrix. The morphology and the dispersion of CI are investigated by field emission scanning electron microscopy, which indicates a uniform distribution of CI in the PS matrix after 2 h of milling. The thermal behavior results indicate no significant degradation of the PS when there is a slight increase in the onset temperature with the addition of CI powder, when compared to the as-received PS pellet. After milling, there are no interactions between the CI and the PS matrix, as confirmed by Fourier transformed infrared spectroscopy. In this study, the milled CI-PS powder is extruded to make filaments, and can have potential applications in the 3-D printing industry.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.324-329
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• 2015

First-principles investigations on the hybrid one dementional hexagonal hybrboron-nitride nano ribbons (BNNRs) with a armchair graphene nano-ribbons(AGRNRs), are presented. Electronics properties of the mixed armchair BNC nano-ribbon (BNCNRs) structure show control of a band gap on all cases at the special K-point. And we have studied, the band gap is direct in all cases. The band gap of mixed ABNCNRs could be divided into three groups (${\Delta}3p$, ${\Delta}3p+1$ and ${\Delta}3p+2$) and decrease with the increase of the width. Also these results show similar to the AGNRs case. Different from the band gap value ordering of AGNRs (${\Delta}3p+1$ > ${\Delta}3p$ > ${\Delta}3p+2$), the ordering of ABNCNRs is ${\Delta}3p$ > ${\Delta}3p+1$ > ${\Delta}3p+2$. The discrepancy may come from the differences between the edges of AGRNRs and the boundaries of hybrid BNCNRs. In addition, the bandgap of ABNCNRs are much smaller than those of the corresponding AGNRs. Our results show that the origin of band gap for BNCNRs with armchair shaped edges arises from both quantum confinement effect of the edges. These results similar to thecase of AGNRs. These properties of hybrid BN/C nano-ribbon structure may offer suitable bandgap to develop nnanoscale electronics and solar cell beyond individual GNRs and BNNRs.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.72-72
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• 2012

The next generation electronics need to not only be smaller but also be more flexible. To meet such demands, electronic devices using two dimensional (2D) atomic crystals have been studied intensely. Especially, graphene which have unprecedented performance fulfillments in versatile research fields leads a parade of 2D atomic crystals. In this talk, I will introduce the electrical characterization and applications of graphene for prominently electrical transistors realization. Even the rising 2D atomic crystals such as hexagonal boron nitride (h-BN), molybdenum disulfide (MoS2) and organic thin film for field effect transistor (FET) toward competent enhancement will be mentioned.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.115.1-115.1
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• 2014

Atom-thick 2-dimensional materials such as graphene, h-BN and MoS2 hold substantial potential for applications in future molecular-scale integrated electronics, transparent conducting membranes, nanocomposites, etc. From a fundamental point of view, 2-dim crystal-solid substrates can also serve as a unique system to study various physicochemical phenomena occurring at low dimensions or interfaces. In this talk, I will present our recent Raman spectroscopy studies on the surface science problems of graphene: interfacial charge transfer, molecular diffusion in confined space and structural deformation.

• Vacuum Magazine
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• v.5 no.2
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• pp.18-22
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• 2018

wo dimensional (2D) van der Waals (vdW) nanosheet semiconductors have recently attracted much attention from researchers because of their potentials as active device materials toward future nano-electronics and -optoelectronics. This review mainly focuses on the features and applications of state-of-the-art vdW 2D material devices which use transition metal dichalcogenides, graphene, hexagonal boron nitride (h-BN), and black phosphorous: field effect transistors (FETs), complementary metal oxide semiconductor (CMOS) inverters, Schottky diode, and PN diode. In a closing remark, important remaining issues of 2D vdW devices are also introduced as requests for future electronics and photonics applications.