• Communications of the Korean Mathematical Society
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• v.10 no.4
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• pp.875-880
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• 1995

Let $S_p(\alpha)$ denote the class of the Spirallike functions of order $\alpha, 0 < $\mid$\alpha$\mid$ < \frac{\pi}{2}$ Let $\Pi_N$ denote the subset of $S_p(\alpha)$ consisting of all products $z\Pi^N_{j=1}(1-u_j z)^{-mt_j}$ where $m = 1 + e^{-2i\alpha},$\mid$u_j$\mid$ = 1, t_j > 0$ for $j = 1, \cdots, N$ and $\sum^{N}_{j=1}{t_j = 1}$. In this paper we prove that extreme points of $S_p(\alpha)$ may be found which lie in $\Pi_N$ for some $N \geq 2$. We are let to conjecture that all exreme points of $S_p(\alpha)$ lie in $\Pi_N$ for somer $N \geq 1$ and that every such function is an extreme point.

• Communications of the Korean Mathematical Society
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• v.28 no.1
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• pp.71-77
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• 2013

Consider a multiplicative group of integers modulo $n$, denoted by $\mathbb{Z}_n^*$. Any element $a{\in}\mathbb{Z}_n^*$ is said to be a semi-primitive root if the order of $a$ modulo $n$ is ${\phi}(n)/2$, where ${\phi}(n)$ is the Euler phi-function. In this paper, we discuss some interesting properties of the multiplicative groups of integers possessing semi-primitive roots and give its applications to solving certain congruences.

• Korean Journal of Mathematics
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• v.4 no.1
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• pp.45-49
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• 1996

Let $F_0$ be the maximal real subfield of $\mathbb{Q}({\zeta}_q+{\zeta}_q^{-1})$ and $F_{\infty}={\cup}_{n{\geq}0}F_n$ be its basic $\mathbb{Z}_p$-extension. Let $A_n$ be the Sylow $p$-subgroup of the ideal class group of $F_n$. The aim of this paper is to examine the injectivity of the natural $mapA_n{\rightarrow}A_m$ induced by the inclusion $F_n{\rightarrow}F_m$ when $m>n{\geq}0$. By using cyclotomic units of $F_n$ and by applying cohomology theory, one gets the following result: If $p$ does not divide the order of $A_1$, then $A_n{\rightarrow}A_m$ is injective for all $m>n{\geq}0$.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.405-408
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• 1998

Due to the large conduction band discontinuity between emitter base, OmGaAs HBT has an advantge to enable the hot electrons to inject into the base. In this paper, InAlGaAs/InGaAs HBT with the various emitter junction gradings and the modified collectors are simulated and analyzed by HMC(hybrid monte carlo) simulator in order to find a optimal structure for the shortest transit time. A minium base transit time (.tau.$_{b}$ ) of 0.21 ps was obtained for HBT with the grading layer, which is parabolically graded from x=1.0 to x=0.5. The minimum collector transit time (.tau.$_{c}$ ) of 0.31ps was found when the collector was modified by inserting p$^{[-10]}$ and p$^{+}$ layers. Thus HBT in combination with the emitter grading and the modified collector layer showed the cut-off frequency (f$_{T}$) of 183GHz.z.z.

• Honam Mathematical Journal
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• v.33 no.2
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• pp.181-186
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• 2011

Consider a multiplicative group of integers modulo n, denoted by $\mathbb{Z}_n^*$. Any element $a{\in}\mathbb{Z}_n^*$ n is said to be a semi-primitive root if the order of a modulo n is $\phi$(n)/2, where $\phi$(n) is the Euler phi-function. In this paper, we classify the multiplicative groups of integers having semi-primitive roots and give interesting properties of such groups.

• BMB Reports
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• v.30 no.4
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• pp.253-257
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• 1997

Negative ion fast atom bombardment (FAB) mass spectra were found to allow the determination of the linkage positions in a series of underivatized linkage-isomeric oligosaccharides. A previous work (Laine et al., 1988) reported that ion patterns of linkage-isomeric trisaccharides could be distinguished by a positive ion. Negative ion FAB collison-activated dissociation (CAD) mass spectrometry (MS) spectra of trisaccharides exhibited better sensitivity than the positive ion mode and provided specific fragmentation patterns according to the linkage positions. Especially, the fragmentations, m/z 205 in F6 and m/z 221 in G6, not occuring in 1-3 or 1-4 linkage. were an indication of 1-6 linkage, by changing collision energies from + 10 eV to +60 eV. The survival ratios of molecular ions in each collision energy set gave support to previous results in which the order of bond stability was 1-6>1-4>1-3 linkage.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.61.2-61.2
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• 2018

ZwCL 1447.2+2619 is a merging galaxy cluster at z=0.37 with clear substructures in X-ray emission and galaxy distribution. In addition, the system possesses distinct radio relics. In order to constrain the merger scenario, it is necessary to measure both the distribution and mass of the cluster dark matter. We perform weak lensing analysis of ZwCL 1447.2+2619 using Subaru imaging data. We detect clear lensing signal from the cluster after carefully addressing instrumental systematics. In this poster, we present our preliminary results on our mass reconstruction and discuss the comparison with X-ray and radio results.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.361-363
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• 1997

Electronic devices are very weak against lightning surges injected from grounding systems and can be damaged. The malfunction and damage of electronic circuits bring about several disadvantages such as low operation performances, a lot of economical losses, and etc. In order to obtain the effective protection measure of electronic devices from overvoltages and lightning surges, the analysis of the transient grounding impedances is very important. The aim of this work is to evaluate the behaviors of transient grounding impedances under impulse currents and to investigate the effect of grounding lead wire. Z-t, Z-i and V-i curves of transient grounding impedance under impulse current waveforms have been measured and analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.6
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• pp.554-562
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• 1987

In this paper, we have proposed the RC Wien-Bridge oscillator consisting of three oprational amplifiers in order to improve the frequency range, and the proposed oscillator has been realized a new SC Wien-Bridge oscillator for LSI realization by the forward Z transform method. The realized SC oscilltor has been affirmed that the frequency range has been improved more than Reddy's. Budak and Nay's by the analysis of pole loci as a frequency function f. Also, it has been confirmed that the designed SC oscillator has been satisfied substantially the oscillated condition by the open-loop measurements.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.1
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• pp.42-50
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• 1999

This study investigated the effects of surface treatment for filling resins on the surface texture of denture resin teeth by the use of scanning electron microscope. This study also evaluated the bond strength of filling resins to denture resin teeth. The denture resin teeth in this study was Endura Posterio(Shofu Co., Japan). The ailing resins used were Coe-cure(Coe Co., USA), Vertex RS (Dentimax Ziest, Holland), and light cured resin Z-100(3M Co., USA). The test sample were divided into 3 parts. Group 1 : Sandblasted with $50{\mu}m$ Aluminum oxide. Group 2 : Treated with #60 silicone carbide paper Group 3 : Treated with monomer brush application. Control Group : No Treatment. The results were as follows ; 1. The bond strength of filling resins to denture resin teeth is increased by surface treatment. 2. Regardless of the filling resins, there was a significant difference with # 60 silicone carbide paper treated group. 3. Regardless of each group, the bond strength according to the filling resins were decreased in the following order: Vertex RS, Coe-cure and Z-100.