• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.916-920
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• 2003

The change of structure and morphology in ( $U_{0.913}$G $d_{0.087}$) $O_2$ during oxidation at 475$^{\circ}C$ and heat treatment at 130$0^{\circ}C$ in air were investigated using XRD, SEM, and EPMA. The ( $U_{0.913}$G $d_{0.087}$) $O_2$ cubic phase converted to ( $U_{0.913}$G $d_{0.087}$)$_3$ $O_{8}$ orthorhombic phase by oxidation at 475$^{\circ}C$ in air. The XRD and EPMA result of the 130$0^{\circ}C$ heat treated powder revealed that ( $U_{0.913}$G $d_{0.087}$)$_3$ $O_{8}$ orthorhombic phase was separated into $U_3$ $O_{8}$ and ( $U_{0.67}$G $d_{0.33}$) $O_{2+}$x/ cubic phase. The weight variations of (U,Gd) $O_2$ with various Gd contents were measured using TGA at the same heat treated condition. The weight variation during the heat treatment of Gd dissolve (U,Gd) $O_2$ in air can be expressed in terms of phase reaction equations related with oxidation and phase separation. Based on these phase reaction, a initial content of Gd dissolved in (U,Gd) $O_2$ can be exactly calculated by measuring the weight change during the heat treatment.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.778-784
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• 2005

It has been found that the addition of cosurfactant is necessary in order to expand three phase region containing middle phase microemulsion in ternary systems containing alkyl ethoxylate (AEO) nonionic surfactant, commercial lubricant and water. Phase behavior in the surfactant systems with addition of cosurfactant over a temperature range of 30 to $60^{\circ}C$ showed different trends depending on surfactant, temperature and chain length of alcohol added. For the $C_{12}E_4$ system, addition of n-pentanol and n-hexanol both produced a three phase region over a wide range of temperatures but the middle-phase formed was found to be a $L_3$ or D' phase which would not facilitate solubilization of high molecular weight lubricants. On the other hand, for the $C_{12}E_5$ system, the middle-phase microemulsion was found to be formed with addition of a rather long-chain alcohol such as n-hexanol, n-heptanol, n-octanol, or n-nonanol. The results shown with the addition of cosurfactant was understood in connection with interfacial tension measurements and composition analysis. The inability of the hydrocarbon region of the surfactant films to incorporate the large lubricant molecules and high solubility of a hydrophobic surfactant are thought to be the chief reasons for poor solubilization with D' phase.

• East Asian mathematical journal
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• v.36 no.3
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• pp.349-357
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• 2020

For a nondegenerate projective curve C ⊂ ℙ^r of degree d, it was shown that the Castelnuovo-Mumford regularity reg(C) of C is at most d - r + 2. And the curves of maximal regularity which attain the maximally possible value d - r + 2 are completely classified. In this short note, we first collect several known results about curves of maximal regularity. We provide a new proof and some partial results. Finally we suggest some interesting questions.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.13-16
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• 1990

균일한 positive column의 상세한 이론이 충돌 단면적 곡선과 공진 방사 그리고 다단계 여기(multistage)와 이온화 과정을 고려하여 0.5에서 5mmHg 압력에서 수은과 희유가스(rare-gas)가 혼합되어 있는 D.C.형광 램프 방전에 대해 전개된다. 온도와 이온, 비여기원자, 여기원자의 밀도가 수치해석에 의하여 계산된다.

• Bulletin of the Korean Mathematical Society
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• v.53 no.3
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• pp.943-957
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• 2016

We introduce a 2-variable weighted shift, denoted by $S_2$(a, b, c, d), which arises naturally from analytic function space theory. We investigate when it is subnormal, and compute the Berger measure of it when it is subnormal. And we apply the results to investigate the relationship among 2-variable subnormal, hyponormal and 2-hyponormal weighted shifts.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1213-1216
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• 1987

In this paper, the application of AMFC(adaptive model - following-control) algorithm to the D.C motor speed control is investigated by using the 68000 microprocessor. Computer simulation in discrete AMFC algorithm shows that output errors caused by the external input and the variation of parameters in D.C motor are converged to zero.

• Journal of the Chungcheong Mathematical Society
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• v.19 no.2
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• pp.111-121
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• 2006

All d-homogeneous $C^*$-algebras $T^d$ over $\prod^{s_4}S^4{\times}\prod^{s_2}S^2{\times}\prod^{s_3}S^3{\times}\prod^{s_1}S^1$ are constructed. It is shown that $T^d$ are strongly Morita equivalent to $C(\prod^{s_4}S^4{\times}\prod^{s_2}S^2{\times}\prod^{s_3}S^3{\times}\prod^{s_1}S^1)$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.4
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• pp.156-160
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• 1982

A Comb Filter(C.F.) is constucted with a N-stages one-dimensional B.B.D.(Bucket-Brigade Device) delay line. One channel of the B.P.F. (Band Pass Filter) Bank is experimented, which includes a R.F.(Recursie Filter) using S/H circuits cascaded to the C.F. This algorithm of the C.F.B.(Comb Filter Bank) becomes the parallel spectrum analyzer circuit. The algorithm has less number of multiplication than that of FFT and improves the SNR.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.580-585
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• 1986

This paper deals with "chattering" problem in variable structure control system. For digital computer control, chattering reduction algorithm in Analog-VSC is extended to Discrete-VSC. The proposed algorithm is applied to position control of D.C Servo Motor by using 6502 .mu.-processor. The improved transient response, as well as a considerable reduction of chattering, is illustrated experimentally.imentally.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.314-319
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• 2016

Testate amoebae are useful organisms when evaluating the condition of freshwater ecosystems and wetland habitats. Herein, I report on seventeen unrecorded species of testate amoebae from Korea: Arcella arenaria, A. costata, A. hemisphaerica, Centropyxis constricta, C. discoides, C. spinosa, Difflugia amphora, D. globulosa, D. longicollis, D. penardi, Heleopera rosea, Hyalosphenia subflava, Nebela militaris, N. penardiana, Netzelia wailesi, Cyphoderia ampulla, and C. trochus.