• Journal of the Korean Institute of Navigation
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• 제25권1호
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• pp.53-60
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• 2001

This paper presents the fabrication of the LNA which is operating at 2.13 ~ 2.16 GHz for IMT-2000 front-end receiver using series feedback and resistive decoupling circuit. Series feedback added to the source lead of a GaAs FET keeps the low noise characteristics and drops the input reflection coefficient of a low noise amplifier simultaneously. Also, it increases the stability of the LNA. Resistive decoupling circuit is suitable for input stage matching because a signal at low frequency is dissipated by a resistor in the matching network. The amplifier consists of GaAs FET ATF-10136 for low noise stage and VNA-25 which is internally matched MMIC for high gain stage. The amplifier is fabricated with both the RF circuits and self bias circuit on the Teflon substrate with 3.5 permittivity. The measured results of the LNA which is fabricated using the above design technique are presented more than 30 dB in gain, PldB 17 dB and less than 0.7 dB in noise figure, 1.5 in inputㆍoutput SWR(Standing Wave Ratio).

• Journal of Korea Foundry Society
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• 제31권1호
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• pp.11-17
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• 2011

The effect of CaO addition to AM60B Mg alloy on tensile properties has been investigated, with focus on strength and ductility at room and elevated temperatures. The 0.25-0.65wt% CaO added AM60B Eco-Mg diecastings were prepared by high pressure die casting using Buhler 1,450-ton cold chamber machine without $SF_6$ and $SO_2$ gases. The microstructures and tensile properties of each alloy were tested. The results show that the grains of AM60B are refined and the mechanical properties increase with CaO addition at room temperature. The improvement of strength and ductility is prominent at 0.45-0.55wt% CaO addition. Also, improved mechanical properties are maintained at elevated temperature of $150^{\circ}C$. CaO addition results in $Al_2Ca$ phase formation mostly on the grain boundaries. This phase leads to the refinement of grain structures and improvement of ductility as well as strength. The suppression of ${\beta}-Mg_{17}Al_{12}$ phase as well as the decrease of fracture surface porosity and other casting defects caused by melt cleanliness also contribute to the enhancement of mechanical properties of AM60B Eco-Mg at room and elevated temperature.

• Polymer(Korea)
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• 제26권1호
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• pp.98-104
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• 2002

This study was investigated to fabricate the isotropic $Nd_2Fe_{14}B$/epoxy bonded magnets with high characteristics paroduced by compression molding. The magnetic characteristics of the bonded magnets were directly proportional to the density of the magnets and were enhanced by using raw $Nd_2Fe_{14}B$ magnetic powders, having the mean particle size of $200{\mu} m$.without additional milling process. The high characteristics of the bonded magnets were achieved at the following conditions: epoxy resin of 2.0 wt%, silane coupling agent of 0.8 wt%, curing agent of 0.7 wt% on the base of magnetic powders, and curing condition of $150^{\circ}C$/3 hrs. The bonded magnets at the optimum conditions indicated the high characteristics such as the density of 6.1 g/㎤, the remanent flux density of 7.1 kG, the maximum energy product of 9.7 MGOe, and the compressive strength of 17 kg/$mm^2$.

• Korean Journal of Crystallography
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• 제15권2호
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• pp.88-92
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• 2004

An organometallic compound, $(C_{16}H_{21}B_{10}BrOSn)$, was synthesized from o-carborane, closo-1-[(methoxyl)methyl]-o-carborane $(HCab^o)$, and $SnMe_2Br_2$. The molecular structure of this complex has been determined by X-ray diffraction. Crystallographic data: orthorhombic, space group Pna2, a = 17.9292(15)$\AA$, b= 7.2066(4)$\AA$, c=13.0582(10)$\AA$, Z=4, V=1687.2(2) $\AA^3$. The structure was solved by direct methods and refined by full-matrix least-squares methods to give a model with a reliability factor R=0.0574 for 1724 reflections.

• The Journal of Korean Medicine
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• 제37권2호
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• pp.45-52
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• 2016

Objectives: The purpose of this study is to evaluate the clinical effects of Muscle Energy Technique(MET) for peripheral facial paralysis. Methods: 60 Patients were divided into two groups. Group A(n=30) received the treatment with existing Korean medicine. Group B(n=30) received the MET with existing Korean medicine. It was performed once a day, five time per a week for three weeks. we analyzed Yanagihara's score and House-Brackmann scale Results: A week after MET treatment, Yanagihara's score average of Group A is $7.17{\pm}6.34$. Yanagihara's score average of Group B is $8.84{\pm}5.22$. (p=0.72). Two weeks after MET, Yanagihara's score average of Group A is $12.39{\pm}4.94$. Yanagihara's score average of Group B is $15.12{\pm}3.20$. (p=0.04). Three weeks after MET, Yanagihara's score average of Group A is $17.11{\pm}5.31$. Yanagihara's score average of Group B is $22.78{\pm}3.67$. (p=0.01). A is $3.87{\pm}1.36$. House-Brackmann Scale average of Group B is $3.64{\pm}1.76$. (p=0.63). Two weeks after MET treatment, House-Brackmann Scale average of Group A is $3.20{\pm}0.97$. House-Brackmann Scale average of Group B is $3.02{\pm}1.03$. (p=0.05). Three weeks after MET, House-Brackmann Scale average of Group A is $2.84{\pm}1.12$. House-Brackmann Scale average of Group B is $2.23{\pm}0.78$. (p=0.04). Conclusion: MET treatment is effective for improve the symptoms of peripheral facial paralysis. Therefore, it will be used to peripheral facial paralysis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제38권4호
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• pp.27-37
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• 2001

The design, fabrication, and an experimental implementation of the strip patch antenna coupled with a H-shaped aperture arc presented in this paper. The proposed antenna has the wide bandwidth, high gain, and low cross-polarization levels. We measured the VSWR, smith chart impedance characteristic, co/cross polarization pattern, gain, and so on. The measured bandwidth of this antenna is 47.1 %. To reduce the back lobe and increase the gain, when the reflector is used, cross polarization level is below -18.2dB at E-plane and below 25.7 dB at H -plane. The maximum gain at 2.05 GHz is also 10.4 dBi and the 3 dB gain bandwidth with center frequency at 2.17 GHz is 24 %, which is the wide bandwidth. This antenna can find applications in mobile communication, wireless LAN, RF communication system, and so on.

• Archives of Pharmacal Research
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• 제10권1호
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• pp.14-17
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• 1987

Several new imidazo [1, 2-b] pyrazole, pyrazolo [5, 1-c]-1, 2, 4-triazine and pyrazolo [5, 1-c] triazole derivatives were prepared from the reaction of 3-antipyrinyl-5-aminopyrazole or its diazonium salt with .alpha.-chloroacetyl derivatives.

• Journal of the Chungcheong Mathematical Society
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• 제10권1호
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• pp.17-22
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• 1997

Let B be the open unit ball in the complex space $\mathbb{C}^n$. A holomorphic function $f:B{\rightarrow}C$ which satisfies sup{(1- ${\parallel}\;{\nabla}_zf\;{\parallel}\;{\mid}z{\in}B$} < $+{\infty}$ is called Bloch type function. In this paper, we will find some integral representation of Bloch type functions.

• The Pure and Applied Mathematics
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• 제17권2호
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• pp.115-130
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• 2010

Let $\cal{A}$ be a unital Banach algebra. If f : $\cal{A}{\rightarrow}\cal{A}$ is an approximately quadratic derivation in the sense of Hyers-Ulam-J.M. Rassias, then f : $\cal{A}{\rightarrow}\cal{A}$ is anexactly quadratic derivation. On the other hands, let $\cal{A}$ and $\cal{B}$ be Banach algebras.Any approximately generalized homomorphism f : $\cal{A}{\rightarrow}\cal{B}$ corresponding to Cauchy, Jensen functional equation can be estimated by a generalized homomorphism.

• Bulletin of the Korean Mathematical Society
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• 제52권3호
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• pp.825-836
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• 2015

In this article, we discuss the complete moment convergence for arrays of B-valued random variables. We obtain some new results which improve the corresponding ones of Sung and Volodin [17].