• Electrical & Electronic Materials
• /
• v.9 no.2
• /
• pp.152-158
• /
• 1996

Optical absorption and photoconductivity spectra of undoped and Co-doped Cd$_{4}$GeSe$_{6}$ single crystals, grown by the chemical transport reaction using iodine as a transporting agent, were investigated. At 20K, the optical energy gaps of the single crystals are 1.934eV for Cd$_{4}$GeSe$_{6}$ and 1.815eV for Cd$_{4}$GeSe$_{6}$ :Co$^{2+}$. The photoconductivity spectra of these single crystals were closely investigated over the temperature range 20-290K. At 20K, the photoconductivity peaks were located at 1.797eV, 1.347eV for Cd$_{4}$GeSe$_{6}$ and 1.815eV, I,.57eV, 1.46eV and 1.38eV for Cd$_{4}$GeSe$_{6}$ :Co$^{2+}$, respectively.ely.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.6
• /
• pp.811-814
• /
• 1993

Properties of a protease purified from Sarcodon asparatus(Berk.) S. Ito have been investigated. The enzyme displays as a glycosylated serine protease. The sequence for the 21 amino acids of the N-terminal side in the enzyme was determined by automated sequence analysis. The sequence was V-T-T-K-Q-T-N-A-P-W-G-L-G-N-I-S-T-T-N-K-L-.

• Journal of the Korean Society of Tobacco Science
• /
• v.25 no.2
• /
• pp.128-136
• /
• 2003

Although tobacco smoke has been known to have genotoxicity as well as cytotoxicity, the sensitivity of the cell lines used against cigarette smoke is poorly understood. The objective of this study was to evaluate and compare the genotoxicity of several cell lines, which are routinely used in the in vitro assays, with cigarette smoke condensate(CSC) of Kentucky Reference Cigarette 1R4F. In the micronucleus(MN) induction assays, murine(CHO-K1, V79, BALB/c 3T3) cell lines and human(MCF-7, A549) ones were used. As a result, the CSC exhibited cytotoxicity with a concentration-dependent response in all cell lines. EC$_{50}$ of CSC in CHO-K1, V79, BALB/c 3T3, MCF-7 and A549 were 140, 125, 100, 116 and 109 $\mu\textrm{g}$/mL, respectively. On the other hand, the spontaneous micronucleated cell(MNC) frequency was stable and reproducible in every cell lines tested in this study. The dose-response of various cell lines to the induction of MN by CSC was estimated using linear regression analysis. CSC(0～100 $\mu\textrm{g}$/mL) caused a dose-dependent MN induction in CHO-K1, V79, BALB/c 3T3 and MCF-7 cell lines. Putting together all the data obtained and linear regression analysis of the data, we concluded that V79 cells are more susceptible to the accurate assessment of CSC-induced MN than the others.s.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.15 no.1
• /
• pp.1-9
• /
• 2005

A stoichiometric mixture of evaporating materials for AgGaS₂ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, AgGaS₂ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were 590℃ and 440℃, respectively. The temperature dependence of the energy band gap of the AgGaS₂ obtained from the absorption spectra was well described by the Varshni's relation, E/sub g/(T) = 2.7284 eV - (8.695×10/sup -4/ eV/K)T²/(T + 332 K). After the as-grown AgGaS₂ single crystal thin films was annealed in Ag-, S-, and Ga-atmospheres, the origin of point defects of AgGaS₂ single crystal thin films has been investigated by the photoluminescence (PL) at 10 K. The native defects of V/sub Ag/, V/sub s/, Ag/sub int/, and S/sub int/ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Ag-atmosphere converted AgGaS₂ single crystal thin films to an optical n-type. Also, we confirmed that Ga in AgGaS₂/GaAs crystal thin films did not form the native defects because Ga in AgGaS₂ single crystal thin films existed in the form of stable bonds.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.8 no.1
• /
• pp.1-7
• /
• 2014

In this study, the effect of the automotive haptic-seat technology which can transmit the driving information by the vibro-stimulus from the seat was investigated to overcome previous system's limitation relied on the visual and audial method and to help handicap driving. A prototype haptic seat covers with 30 coin-type motors and driver module were developed for this sake. A driving simulator on the 6-DOF motion-base was used for driving situation and we executed the seat vibro-stimulus test with 10 young participants who have normal tactile sense. The haptic recognition ratio by 30 locations was measured and analyzed in the result. The intensity of vibro-stimulus was adjusted by input voltage of motors (1.5V,2.5V,3.5V). All vibro-stimulus locations at 2.5V and 3.5V could be recognized by all participants and even in the lowest recognition ratio of 1.5V. The results showed that the seat vibration stimulus could be useful to transfer the drivers' information while driving.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.915-917
• /
• 1992

This paper shows the discharge characteristics in flowing air with variation of tempearature(T) under the needle-needle gap. Flowing air duct of this investigation is circular tube. The flow at the experimental position's section is described as fully developed laminar flow. The important results obtained from this study are as follows. The ratio sparkover voltages to the Reynolds number(Re) increases with decreasing the Re. The velocity profiles can be visualized by this experimental method. The breakdown voltage ($V_{s1}$) for variation of T at 1[m/s] can be expressed by $V_{s1}$ = $K_1$(23.98$\rho$d + 6.98$\sqrt{\rho{d}}$) [kV].

• Kyungpook Mathematical Journal
• /
• v.46 no.4
• /
• pp.581-589
• /
• 2006

We characterize the linear operators which preserve the factor rank of integer matrices. That is, if $\mathcal{M}$ is the set of all $m{\times}n$ matrices with entries in the integers and min($m,n$) > 1, then a linear operator T on $\mathcal{M}$ preserves the factor rank of all matrices in $\mathcal{M}$ if and only if T has the form either T(X) = UXV for all $X{\in}\mathcal{M}$, or $m=n$ and T(X)=$UX^tV$ for all $X{\in}\mathcal{M}$, where U and V are suitable nonsingular integer matrices. Other characterizations of factor rank-preservers of integer matrices are also given.

• Transactions of Materials Processing
• /
• v.24 no.1
• /
• pp.44-51
• /
• 2015

The current study seeks to examine the effects of V and C additions on the mechanical and low thermal expansion properties of a high strength invar base alloy. The base alloy (Fe-36%Ni-0.9%Co-2.75%Mo-0.7Cr-0.23Mn-0.17Si-0.3%C, wt.%) contains $Mo_2C$ carbides, which form as the main precipitate. In contrast, alloys with additions of 0.4%V+0.3%C (alloy A) or 0.4%V+0.45%C (alloy B) contain $Mo_2C$+[V, Mo]C carbides. The average thermal expansion coefficients of these high strength invar based alloys were measured in the range of $5.16{\sim}5.43{\mu}m/m{\cdot}^{\circ}C$ for temperatures of $15{\sim}230^{\circ}C$. Moreover, alloy B showed lower thermal expansion coefficient than the other alloys in this temperature range. For the mechanical properties, the [V, Mo]C improved hardness and strengths(Y.S. and T.S.) of the high strength invar base alloy. T.S.(tensile strength) and Y.S.(yield strength) of hot forged alloy B specimen were measured at 844.6MPa and 518.0MPa, respectively. The tensile fractography of alloy B exhibited a ductile transgranular fracture mode and voids were initiated between the [V, Mo]C particles and the matrix. Superior properties of high strength and low thermal expansion coefficient can be obtained by [V, Mo]C precipitation in alloy B with the addition of 0.4%V and 0.45%C.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.282-285
• /
• 2003

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410\;^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680\;^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}\;and\;295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.68\;{\times}\;10^{-4}eV/K)T^2/(T\;+\;155\;K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CuAlSe_2$ have been estimated to be 0.2026 eV and 0.2165 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the $\Delta$so definitely exists in the ${\Gamma}_5$ states of the valence band of the $CuAlSe_2$. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.837-1-837-3
• /
• 1998