• 한국전기전자재료학회논문지
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• 제24권12호
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• pp.969-976
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• 2011

In this study we aims to evaluate the effects of 1/3 mol% $Co_3O_4$ addition on the reaction, microstructure development, resultant electrical properties, and especially the bulk trap and grain boundary properties of $ZnO-Bi_2O_3-Sb_2O_3$ (Sb/Bi=2.0, 1.0, and 0.5) system (ZBS). The samples were prepared by conventional ceramic process, and characterized by XRD, density, SEM, I-V, impedance and modulus spectroscopy (IS & MS) measurement. In addition of $Co_3O_4$ in $ZnO-Bi_2O_3-Sb_2O_3$ (ZBSCo), the phase development, density, and microstructure were controlled by Sb/Bi ratio. Pyrochlore on cooling was reproduced in all systems. The more homogeneous microstructure was obtained in ZBSCo (Sb/Bi=1.0) system. In ZBSCo, the varistor characteristics were improved drastically (non-linear coefficient ${\alpha}$=23~50) compared to ZBS. Doping of $Co_3O_4$ to ZBS seemed to form $V^{\cdot}_o$(0.33 eV) as dominant defect. From IS & MS, especially the grain boundary of Sb/Bi=0.5 system is composed of electrically single barrier (0.93 eV) and somewhat sensitive to ambient oxygen with temperature.

• 한국전기전자재료학회논문지
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• 제23권11호
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• pp.875-879
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• 2010

In this study, we have characterized the roles of $Cr_2O_3$ on the sintering and electrical properties of ZnO. The densification and grain growth of Cr-doped ZnO (ZCr) system was mainly influenced by Cr contents. In the beginning of sintering, the densification of ZnO was retarded as reducing the Zni concentration in ZnO lattice with Cr doping. And the densification and grain growth of ZnO was more retarded due to a formation of spinel phase with increasing the Cr contents. ZCr system revealed varistor behavior with nonlinear coefficient $\alpha$ of 3~23 depending on the sintering temperature, implying double Schottky barrier formation on the grain boundary of ZnO. Especially the best varistor characteristics should be developed with 0.1~0.5 at% Cr contents and under $1100^{\circ}C$ in ZCr systems.

• 한국세라믹학회지
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• 제43권11호
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• pp.693-699
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• 2006

Textured $Bi_{0.5}(Na,K)_{0.5}TiO_3-BiFeO_3$ ceramics were prepared by the reactive-templated grain growth process, using platelike $Bi_4Ti_3O_{12}$ particles. The effects of chemical composition in $Bi_{0.5}(Na,K)_{0.5}TiO_3$ on texture development and densification were examined. Textured ceramics were obtained by using $Bi_{0.5}K_{0.5}TiO_3$ as an end member of the solid solution but densification was limited. Dense ceramics were obtained by using $Bi_{0.5}Na_{0.5}TiO_3$ but texture did not develop. Dense, textured ceramics were obtained by using $Bi_{0.5}(Na_{0.5}K_{0.5})_{0.5}TiO_3$.

• 생명과학회지
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• 제13권1호
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• pp.29-33
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• 2003

맥주보리의 양적형질에 대한 유전정보를 얻고자 7개 품종으로 이면교배하여 $F_1$ 세대에 대한 유전자의 분포상태 분산성분.유전력 등을 분석한 결과를 요약하면 다음과 같다. 공시된 품종집단에 대한 $F_1$ 세대의 우성정도를 Vr-Wr graph상에서 볼 때 간장.수장.망장.곡립장.1수립수 등은 초우성으로 유전되었고 경직경.곡립폭 1000립중은 불완전우성으로 유전되었다. 각 형질에 대한 분산분석 결과에서 상가적효과, 우성효과, 모본효과, 정역간의 효과는 간장.수장.망장.경직경.곡립장.곡립폭.1수립수.1000립중 등에서 모두 유의하였다. 유전 분산성분에서 간장.수장.망장.경직경.곡립장.곡립폭.1수립수.1000립중은 우성효과가 상가효과보다 컸다. 협의의 유전력은 수장이 40.06%로서 높았다.

• 한국재료학회지
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• 제16권6호
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• pp.360-366
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• 2006

A series of ZnO thin films were grown by radio-frequency (RF) magnetron sputtering with various RF powers on $SiO_2/Si$(100) substrates at $500^{\circ}C$. Thicknesses of the investigated ZnO films were fixed to about 250nm by changing the growth time based on the changes of growth rates with RF powers. All the ZnO thin films were grown with <0001> preferred orientation. Average grain sizes of about 250nm-thick ZnO films evaluated by FE-SEM, AFM, and TEM were increased by decreasing the RF power. Structural properties addressed by FWHM values of XRD (0002) omega rocking curves and their intensities were better for the smaller grain sized ZnO films grown with high RF powers, which implies small values of tilt for smaller grain sized ZnO films. However, optical properties addressed by intensities of band edge emissions from room temperature and low temperature photoluminescence were better for the larger grain sized ZnO films with low RF power, which implies grain boundaries acted as nonradiation recombination centers.

• 한국재료학회지
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• 제14권2호
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• pp.115-120
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• 2004

Perovskite barium-strontium titanate, $(Ba, Sr)TiO_3$ was prepared and effects of $Sb_2$O$_3$ additives on its PTCR properties were investigated. $The (Ba,Sr)TiO_3$ with 0.05～0.25 mol% $Sb_2$$O_3$ showed semiconducting PTCR behavior and anomalous grain growth was also observed when it was sintered above $1330^{\circ}C$. It was considered that charge compensation by doping 8b203 as well as abnormal grain growth by sintering lead to resistivity reduction from insulating to semiconducting transition.

• Animal Bioscience
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• 제35권12호
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• pp.1911-1920
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• 2022

Objective: This study was performed to determine the apparent metabolizable energy (AME_n) content of tannin-free red/bronze, white/tan and U.S. No. 2 varieties of grain sorghum for feeding Japanese quail and validate their nutrient profile by evaluating effects on performance and carcass traits with full-substitution of corn. Methods: Experiment 1 determined the AME_n content of red/bronze, white/tan, and U.S. No. 2 grain sorghum varieties fed to mixed-sex Japanese quail (Coturnix japonica) (n = 314) at 3 and 6-weeks of age. Analyses were based on a 2×4 factorial treatment design with age and grain types defining the treatments, and a randomized complete block experiment design with cage and trials defining the block. AME_n values were validated by evaluating the performance and carcass traits of Japanese quail (n = 644) from 1 to 40 days of age in Experiment 2 with birds were fed 1 of 4 complete diets. Statistical analyses were conducted on performance data and select individual carcass trait measurements. Results: Determined AME_n values at 3-weeks of age were 3,524±122.03 (red/bronze), 3,252±122.03 (white/tan), and 3,039±123.44 (U.S. No. 2) kcal/kg. At 6-weeks of age, determined AME_n were 3,373±297.35 (red/bronze), 3,279±297.35 (white/tan), and 2,966±298.64 (U.S. No. 2) kcal/kg. Carcass traits showed live body weight (p = 0.0409) and hot carcass weight (p = 0.0234) were greatest in U.S. No. 2; however, carcass yield (p<0.0001) was lowest. No significant differences were observed among treatments for feed intake, feed conversion ratio, breast weight and breast yield (p>0.05). Conclusion: These studies demonstrated that tannin-free grain sorghum varieties may be a potential alternative to corn in quail diets while maintaining growth performance and carcass parameters.

• 한국세라믹학회지
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• 제42권8호
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• pp.588-592
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• 2005

The effect of SiC additive on the densification behavior and microstructural change of $TiB_2$ ceramics was investigated. The infiltration and direct mixing with polycarbosilane (PCS), which was converted to SiC by pyrolysis during sintering, were used for the addition of SiC. The addition of Fe enhanced the densification of $TiB_2$, but which resulted in exaggerated grain growth. However, the addition of PCS enhanced the densification and suppressed the exaggerated grain growth of $TiB_2$. Moreover, the addition of PCS using direct mixing was more effective for suppress of grain growth as compare to the addition of PCS using infiltration.

• Applied Science and Convergence Technology
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• 제26권5호
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• pp.129-132
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• 2017

We report a chemical vapor deposition approach and optimized growth condition to the synthesis of single layer molybdenum disulfide ($MoS_2$). Obtaining large grain size with continuous $MoS_2$ atomically thin films is highly responsible to the growth distance between molybdenum trioxide source and receiving silicon substrate. Experimental results indicate that triangular shape $MoS_2$ grain size could be enlarged up to > 80um with the precisely controlled the source-to-substrate distance under 7.5 mm. Furthermore, we demonstrate fabrication of a memory device by employing poly(methyl methacrylate) (PMMA) as insulating layer. The fabricated devices have a PMMA-$MoS_2$/metal configuration and exhibit a bistable resistance switching behavior with high/low-current ratio around $10^3$.

• 한국표면공학회지
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• 제48권4호
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• pp.169-173
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• 2015

$CuInSe_2$ thin films which have been widely used for thin solar cells as a light absorber were prepared by hydrazine solution processing, and their microstructural properties were investigated. Hydrazine $CuInSe_2$ precursor solutions were prepared by dissolving $Cu_2S$, S, $In_2Se_3$ and Se powder in hydrazine solvent. Multilayer $CuInSe_2$ chalcopyrite phase thin films were prepared by repeating spin-coating process using the precursor solution. Unfortunately, the presence of the interfaces between each $CuInSe_2$ layer formed by multi-layer coating impeded grain growth across the interface. Here, by doing simple interface engineering to solve the limited grain growth issue, the large grained (${\sim}1{\mu}m$) $CuInSe_2$ thin films were obtained.