• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.4
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• pp.135-139
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• 2004

The layered organic-inorganic hybrid compounds($C_6H_5CH_2NH_3)_2CuCl_4$ and ($NH_3C_6/H_4C_2H_4_6/H_4NH_3)CuCl_4$ have been directly synthesized. From the X-ray diffraction data and the organic guest size, the orientation of the intercalated organic amine was determined. The inorganic sheets consist of $CuCl_4^{2-}$layers of comer-sharing octahedra copper chloride. The protonated organic amine was intercalated into the $CuCl_4^{2-}$layers with bilayer structure for ($C_6H_5CH_2NH_3)_2CuCl_4$ and monolayer structure for ($NH_3C_6/H_4C_2H_4_6/H_4NH_3)CuCl_4$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.364-367
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• 2012

In this paper, AXI4 BUS was implemented using Verilator and C/C++ for verification of SoC platform H/W IP which is based on AXI4 BUS. In this paper we proposed a method to verify the AXI4 BUS based SoC platform H / W IP by implemented AXI4 BUS on PC using Verilator and C/C++. The result shows AXI4 BUS based H/W IP that is verified by implemented AXI4 BUS is to perform the same behavior on FPGA environment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.640-644
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• 1998

We have fabricated Sb/SiC(4H) Schottky barrier diode (SBD) of which characteristics compared with that of Ti/SiC(4H) SBD. The donor concentration of the n-type SiC(4H) obtained by capacitance-voltage (C-V) measurement was about $2.5{\times}10 ^{17}{\textrm}cm^{-3}$. The ideality factors of 1.31 was obtained from the slope of forward current-voltage (I-V) characteristics of Sb/SiC(4H) SBD at low current density. The breakdown field of Sb/SiC(4H) SBD under the reverse bias voltage was about $4.4{\times}10^2V$/cm. The built-in potential and the Schottky barrier height (SBH) of Sb/SiC(4H) SBD were 1.70V and 1.82V, respectively, which were determined by the analysis of C-V characteristics. The Sb/SiC(4H) SBH of 1.82V was higher than Ti/SiC(4H) SBH of 0.91V. However, the current density and reverse breakdown field of Sb/SiC(4H) were low as compared with those of Ti/SiC(4H). The Sb/SiC(4H), as well as the Ti/SiC(4H), can be utilized as the Shottky barrier contact for the high-power electronic device.

• The Korean Journal of Ecology
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• v.6 no.2
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• pp.128-141
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• 1983

The districbution of $C_3; and; C_4$ type plants in Korea were studied. In the standpoint of photosynthetic types, plant distribution in Korea is classified as $C_3; and; C_4$ type plant zones. The forest destroyed by man interference, cultivating areas, and seashore areas are characterized by the dominant of $C_4$ type plants.(Figs. 2, 3, 4, 5) According to the results of this study, $C_3; and; C_4$ type plant distribution in Korea has a great relation to the habitat of plant vegetation (Table 1). The arid areas were in high proportion of C4 flora percenntages, while the well-developed woody forests or the vegetation of humid areas were in lower proportion(Fig.8).

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1080-1081
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• 2006

In this investigation, $B_4C$ based ceramic composites were fabricated by in-situ reaction hot pressing using $B_4C$, TiC SiC powder as starting materials. The reaction synthesized composites by hot pressing at $1950^{\circ}C$ was found to posses very high relative density. The reaction synthesized $B_4C$ composites comprise $B_4C$, $TiB_2$, SiC and graphite by the reaction between TiC and $B_4C$. The newly formed $TiB_2$ and graphite was embedded both inside grain and at grain boundary $B_4C$. The mechanical properties of reaction synthesized $B_4C-TiB_2-SiC$-graphite composites were more enhanced compared to those of monolithic $B_4C$.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.128-131
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• 2003

Formation of$B_4C/Al$composite by pressureless infiltration was investigated by lowering wetting angle via surface modification of $B_4C$powder with alumina precursor. Surface modification was confirmed by zeta potential analysis. The$B_4C/Al$composite was prepared by placing an Al 6061 disk on the$B_4C$preform and heating at $1030{\circ}C$/20 min under a flowing argon, but no infiltration took place for a bare $B_4C$ preform even at$1250{\circ}C$/30 min. Analysis of XRD and SEM showed the $Al_3BC$phase besides$B_4C$and Al, but no trace of deteriorative$A1_4C_3$.

• Tribology and Lubricants
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• v.4 no.2
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• pp.36-43
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• 1988

Titanium carbide(TiC) and titanium nitride(TiN) flims were deposited on $Si_3N_4$-TiC composite cutting tools by chemical vapor deposition(CVD) using $TiCl_4-CH_4-H_2$ and $TiCl_4-H_2-N_2$ gas mixtures, respectively. The nonmetal to metal ratio of deposit increases with increasing $m_{C/Ti}$(mole ratio of CH$_4$ to TiCl$_4$ in the input) for TiC coatings and $m_{N/Ti}$(mole ratio of N$_2$ to TiCl$_4$ in the input) for TiN coatings. The nearly stoiahiometric films could be obtained under the deposition condition of $m_{C/Ti}$ between 1.15 and 1.61 for TiC, and that of $m_{N/Ti}$ between 25 and 28 for TiN. Also maximum microhardness of the coatings can be obtained in these ranges. The interfacial region of TiC coatings on $Si_3N_4$-TiC ceramics is wider than that of TiN coatings according to Auger depth profile analysis, which indicates good interfacial bonding for TiC. Experimental results show that TiC coatings have an randomly equiaxed structure and Columnar structure with(220) preferred orientation can be obtained for TiN coatings. And, multilayer coatings have a dense and equiaxed structure.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.363-369
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• 1996

We have performed Brillouin scattering experiments to investigate the elastic properties of tetragonal symmetry single crystal $PbMoO_4$ and could determine the value of birefringence as well as the whole elastic constants. As a result, $c_11=111.4{\pm}4.4,$$, $c_12=64.7{\pm}3.4$, $c_44=27.0{\pm}0.8$, $c_13=51.9{\pm}2.5$, $c_33=95.5{\pm}1.9$, $c_66=34.5{\pm}4.6$ and $c_16=15.8{\pm}1.2({\times}10^9N/m^2)$ and $n_o-n_e=0.151{\pm}0.018$.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.777-783
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• 2003

The mechanical properties of B$_4$C/Al composites normally depend on the species and quantity of reaction products between B$_4$C and Al and then the control of reaction products is necessary to make desirable composites for lightweight advanced or armor materials. TiB$_2$ is chemically inert with aluminum and has a lower contact angle (85$^{\circ}$ at 100$0^{\circ}C$) to liquid aluminum than B$_4$C. Thus, TiB$_2$ coating on B$_4$C may lower infiltration temperature of aluminum when the B$_4$C/Al composites is fabricated by infiltration process. In this study, the effects of TiB$_2$ on the microstructure and mechanical properties of the B$_4$C/Al composites have been investigated. TiB$_2$ coated B$_4$C powder was prepared using the sol-gel technique. It was found that the B$_4$C surface is homogeneously covered with TiB$_2$ having a particles size of 20-50 nm. While the B$_4$C/Al composites prepared by infiltration after TiB$_2$ coating had 17 wt% of unreacted Al, on the other hand, the B$_4$C/Al composites without coating included 14 wt% of Al. As a result, the composites infiltrated after the coating showed higher fracture toughness and lower hardness. This strongly suggests that TiB$_2$ not only lowers the infiltration temperature, but also inhibits the reaction between B$_4$C and Al.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.338-344
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• 2019

B₄C-SiC composites were fabricated using hot press sintering method without sintering additives at 1,900~2,000℃ under a pressure of 40 MPa. The crystal phase, relative density, microstructure, and mechanical properties of B₄C-SiC composites were evaluated. When B₄C and SiC were uniformly dispersed in the composite, grain growth was inhibited, and a sintered body with a fine and uniform microstructure, with improved mechanical properties, was fabricated. The relative density of B₄C-SiC composites sintered under 2,000℃ of temperature and 40 MPa of pressure was over 99.8 %, and the bending strength and Vicker's hardness at 50 wt% of B₄C were 645 MPa and 30.6 GPa, respectively.