• Journal of the Mineralogical Society of Korea
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• v.32 no.1
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• pp.41-49
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• 2019

Probing the Na environments in Na silicate and aluminosilicate glasses is essential to the macroscopic properties of melts in the Earth. In particular, exploring the atomic structure of Na silicate and aluminosilicate glasses reveals Na-O distance, which plays an important role in transport properties of melts. Here we report the local environment around Na using $^{23}Na$ magic angle spinning (MAS) NMR. We also obtain $^{23}Na$ isotropic chemical shift (${\delta}_{iso}$) of Na silicate and aluminosilicate glasses with varying composition using Dmfit program. The Q mas 1/2 model simulates the experimental results with three simulated peaks while the CzSimple model simulates with one peak. The ${\delta}_{iso}$ decreases with increasing $SiO_2$ content in Na silicate and aluminosilicate glasses. The ${\delta}_{iso}$ increases with increasing $Na_2O$ content in Na-Ca silicate and Na aluminosilicate glasses when the $SiO_2$ content is fixed. Considering the ${\delta}_{iso}$ of Na aluminosilicate glasses available in the previous studies, together with the current simulation results, we confirm that the ${\delta}_{iso}$ has positive correlation with Al / (Al + Si). Those experimental results were reproduced better using Q mas 1/2 model. The disorder of Na in Na silicate and aluminosilicate glasses can be revealed through the simulation of 1D $^{23}Na$ MAS NMR spectra using Dmfit program in a short time.

• Honam Mathematical Journal
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• v.10 no.1
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• pp.23-30
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• 1988

Let C[C, D] and $S^{*}[C,\;D]$ denote the classes of functions g, g(0)=1-g'(0)0=0, analytic in the unit disc E such that $\frac{(zg{\prime}(z)){\prime}}{g{\prime}(z)}$ and $\frac{zg{\prime}(z)}{g(z)}$ are subordinate to $\frac{1+Cz}{1+Dz{\prime}}$ $z{\in}E$, respectively. In this paper, the classes K[A,B;C,D] and $C^{*}[A,B;C,D]$, $-1{\leq}B<A{\leq}1$; $-1{\leq}D<C{\leq}1$, are defined. The functions in these classes are close-to-convex. Using the properties of convolution operators, we deal with some problems for our classes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.91-95
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• 2000

The effects of argon gas flow on the axial temperature gradient near the interface, the oxygen concentration, and the radial oxygen uniformity was investigated for 8-inch CZ silicon growth. As argon flow rate was increased, the temperature gradient was increased in the crystal near the crystavmelt interface and the oxygen content in the crystal was decreased. But the radial oxygen uniformity was deteriorated. It was found that argon flow is one of the important growing parameters to affect the quality of crystals such as oxygen content and uniformity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.539-543
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• 1998

The relationship of growth-in defects such as crystal originated particles (COP), flow pattern defects(FPD), laser scattering tomography defects (LSTD) was investigated in Cz-Si single crystals which had different pulling speed during crystal growing. It is concluded that the density and radial distribution of grown-in defects is strongly dependent on the pulling speed. And as the generation areas of these grown-in defects in a wafer are identical in radial position, they can be generated from same origin during crystal growing.

• Journal of the Korean Ceramic Society
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• v.28 no.6
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• pp.495-501
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• 1991

This study is intended to make defect-free region, denuded zone at the silicon wafer surface for semiconductor device substrates. In this experiment, initial oxygen concentration of starting material CZ-grown silicon wafer, various heat treatment combinations, denuding ambient and the amounts of oxygen reduction were measured, and then denuded zone (DZ) formation and depth were investigated. In Low/High anneal (DZ formation could be achieved), the optimum temperature for Low anneal was 700$^{\circ}C$∼750$^{\circ}C$. In case of High anneal, with the time increased, DZ depth was increased at 1000$^{\circ}C$, 1150$^{\circ}C$ respectively, but on the contrary, DZ depth was decreased at low temperature 900$^{\circ}C$. As well, out-diffusion time below 2 hours was unsuitable for effective Gettering technique even though the temperature was high, and DZ formation could be achieved when initial oxygen concentration was only above 14 ppm in silicon wafer.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.156-161
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• 2001

본 연구에서는 45명의 가상현실 사용자들의 가상현실 전, 중, 후의 생리신호의 변화를 관찰하였고 성격, 능력 특성 설문지, 가상현실 평가 설문지를 이용하여 심리적 영향을 알아보았다. 체온의 변화 양상을 기준으로 하여 가상현실 사용자의 심리생리학적 유형을 나누고 유형별 심리적인 반응 특성을 살펴보았다. 1) A 유형: 가상현실 유행동안 체온이 연속적으로 감소하는 유형. 2) B 유형: 가상현실 윤행초기에 체온이 급격히 증가해서 운행동안 서서히 체온이 상승하는 유형. A 유형에 속하는 사용자들의 성격적 특성은 Holland의 성격 유형이론에 근거하여 실제형의 사람들이 많은 것으로 나타났으며 B 유형은 탐구형, 사회형의 사람들이 많은 경향으로 나타났다. 멀미민감도는 A 유형이 B 유형보다 더 크게 나타났다. A, B 유형의 뇌파분석 결과 정중 전두부 (Fz), 정중 중심부 (Cz)에서 베타파, 감마파 상대파워가 유의미한 차이가 있는 것으로 나타났다. 체온의 변화 양상에 따라 나눈 A, B 유형은 성격 및 능력 특성, 멀미민감도에 있어서 유형간 차이가 있는 것으로 나타났다.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.145-154
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• 2002

CMP (Chemical mechanical polishing) process was used to control the fine grinding process induced mechanical damage of Cz Silicon wafer. Characterization of mechanical damage was carried out using Nomarski microscope, magic mirror and also using angle lapping and lifetime scanner evaluation after heat treatment. Magic mirror and lifetime scanner were very useful for the residual damage pattern characterization and CMP process was effective on the reduction of fine grinding induced mechanical damage.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.162-165
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• 1991

Oxygen behaviors in CZ-silicon wafer, grown by the Lucky Advanced Materials Inc. that is a pioneer of silicon material industries in Korea, were investigated to simulate effects on the device performance of oxygen, neglecting the effect of other impurity content, defects and thermal history. Silicon wafers were annealed through simulated 16K SRAM thermal cycle. As initial oxygen concentration increased up to 16.7ppma the amount of oxygen precipitation increased up to 10.6ppma and the bulk microdefect density increased up to $10.3{\times}10^3/mm^2$, but the depth of the denuded zone decreased to $5.0{\mu}m$

• Journal for History of Mathematics
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• v.17 no.2
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• pp.61-72
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• 2004

In this article we study on didactic transposition and enlargement of the Ceva theorem(if three cevians AX, BY, CZ, one through each vertex of a triangle ABC, are concurrent, then $\frac{BX}{XC}\frac{CY}{YA}\frac{AZ}{ZB}$ = 1). We suggest inverse of the Ceva theorem, some different forms of the Ceva theorem(oriented segment form, trigonometric form, vector form), enlarged the Ceva theorem of polygon and tetrahedron, and in detail propose these proofs.

• Journal of Nutrition and Health
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• v.24 no.2
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• pp.87-96
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• 1991

This study was undertaken to investigate the effect of the levels of dietary Zn and alcohol consumption on lipid metabolism in Sprague-Dawley male rats weighing 80 to 90g for eight weeks. Ninety rats were divided into nine groups according to Zn levels and alcohol consumption such as no alcohol group[low Zn diet group(<1ppm. LZ) control Zn diet group(30ppm. CZ) high Zn diet group(60ppm, HZ)] 10% alcohol consumption group[the same Zn levels as no alcohol group LZLA, CZLA, HZLA] 20% alcohol consumption group[the same Zn levels as no alcohol group, LZHA, CZHA, HZHA] The results obtained were summarized as following : 1) In the serum total cholesterol increased with increasing dietary Zn levels but decreased with alcohol consumption. HDL-cholesterol decreased with alcohol consumption. Triglyce-ride in alcohol group was higher than no alcohol group. In alcohol group triglyceride increased with decreasing dietary Zn levels. 2) In the liver total lipid in alcohol group was higher than no alcohol group HA group showed a significant increase. Triglyceride increased with alcohol consumption. 3) In the serum and liver Zn content increased with increasing dietary Zn levels but decreased with alcohol consumption.