• 한국전자통신학회논문지
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• 제8권11호
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• pp.1749-1754
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• 2013

주기가 $2^n-1$인 이진수열은 부호이론, CDMA와 같은 통신시스템과 암호체계 등 많은 분야에서 폭넓게응용되고 있다. 본 논문에서는 n=2m, m=4k($k{\geq}2$)이고 $d=3{\cdot}2^m-2$일 때 생성되는 비선형 이진수열의 상호상관관계의 빈도를 분석하기 위해 $GF(2^n)$ 위에서 방정식 $x^5+bx^3+b^{2^m}x^2+1=0$의 해의 유형에 대하여 분석하고 서로 다른 해의 개수를 결정하는 알고리즘을 제안한다.

• Korean Journal of Mathematics
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• 제23권4호
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• pp.571-590
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• 2015

Let a, b, q be integers with q > 0. The homogeneous Dedekind sum is dened by $$\Large S(a,b,q)={\sum_{r=1}^{q}}\(\({\frac{ar}{q}}\)\)\(\({\frac{br}{q}}\)\)$$, where $$\Large ((x))=\{x-[x]-{\frac{1}{2}},\text{ if x is not an integer},\\0,\hspace{75}\text{ if x is an integer.}$$ In this paper we study the mean value of S(a, b, q) by using mean value theorems of Dirichlet L-functions, and give some asymptotic formula.

• Journal of Magnetics
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• 제16권3호
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• pp.229-233
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• 2011

Phase evolution during the hydrogen-assisted disproportionation of $Nd_{12.5}Fe_{80.6}B_{6.4}Ga_{0.3}Nb_{0.2}$ alloy was investigated mainly by using a magnetic balance-type thermomagnetic analyser (TMA). In order to avoid any undesirable phase change in the course of heating for TMA, a swift TMA technique with very high heating rate (around 2 min to reach $800^{\circ}C$ from room temperature) was adopted. The hydrided $Nd_{12.5}Fe_{80.6}B_{6.4}Ga_{0.3}Nb_{0.2}$ alloy started to be disproportionated in hydrogen from around $600^{\circ}C$, and the alloy after the early disproportionation (from 600 to $660^{\circ}C$) has been partially disproportionated. The partially disproportionated alloy consisted of a mixture of $NdH_x$, $Fe_3B$, ${\alpha}$-Fe, and the remaining undisproportionated $Nd_2Fe_{14}BH_x$-phase. During the subsequent heating to $800^{\circ}C$ in hydrogen, two additional phases of $Fe_{23}B_6$ and $Fe_2B$ were formed, and the material consisted of a mixture of $NdH_x$, $Fe_{23}B_6$, $Fe_3B$, $Fe_2B$, and ${\alpha}$-Fe phases. During the subsequent isothermal holding at $800^{\circ}C$ for 1 hour, the phase constitution was further changed, and one additional unknown magnetic phase was formed. Eventually, the fully disproportionated $Nd_{12.5}Fe_{80.6}B_{6.4}Ga_{0.3}Nb_{0.2}$ alloy consisted of $NdH_x$, $Fe_{23}B_6$, $Fe_3B$, $Fe_2B$, ${\alpha}$-Fe, and one additional unknown magnetic phase.

• Kyungpook Mathematical Journal
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• 제49권1호
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• pp.167-181
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• 2009

Based on Ricatti equation $XA^{-1}X=B$ for two (positive invertible) operators A and B which has the geometric mean $A{\sharp}B$ as its solution, we consider a cubic equation $X(A{\sharp}B)^{-1}X(A{\sharp}B)^{-1}X=C$ for A, B and C. The solution X = $(A{\sharp}B){\sharp}_{\frac{1}{3}}C$ is a candidate of the geometric mean of the three operators. However, this solution is not invariant under permutation unlike the geometric mean of two operators. To supply the lack of the property, we adopt a limiting process due to Ando-Li-Mathias. We define reasonable geometric means of k operators for all integers $k{\geq}2$ by induction. For three positive operators, in particular, we define the weighted geometric mean as an extension of that of two operators.

• Kyungpook Mathematical Journal
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• 제48권4호
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• pp.529-543
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• 2008

It is shown that every almost linear mapping h : $A{\rightarrow}B$ of a unital PoissonC*-algebra A to a unital Poisson C*-algebra B is a Poisson C*-algebra homomorph when $h(2^nuy)\;=\;h(2^nu)h(y)$ or $h(3^nuy)\;=\;h(3^nu)h(y)$ for all $y\;\in\;A$, all unitary elements $u\;\in\;A$ and n = 0, 1, 2,$\codts$, and that every almost linear almost multiplicative mapping h : $A{\rightarrow}B$ is a Poisson C*-algebra homomorphism when h(2x) = 2h(x) or h(3x) = 3h(x for all $x\;\in\;A$. Here the numbers 2, 3 depend on the functional equations given in the almost linear mappings or in the almost linear almost multiplicative mappings. We prove the Cauchy-Rassias stability of Poisson C*-algebra homomorphisms in unital Poisson C*-algebras, and of homomorphisms in Poisson Banach modules over a unital Poisson C*-algebra.

• 한국전자통신학회논문지
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• 제13권5호
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• pp.943-948
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• 2018

본 논문에서는 GaN MMIC를 활용하여 X-band 레이더용 SSPA모듈을 설계 및 제작하였다. SSPA의 구동 증폭기 단은 Gain Loss를 감안하여 GaN MMIC를 2단으로 구성하였다. 그리고 고출력 SSPA 모듈 구성을 위해 전력증폭단을 4단으로 설계함에 따라 전력분배기와 전력합성기는 4way 방식으로 설계하였다. 제작된 전력 분배기는 -3.0dB 이상의 손실을 나타내었으며, 전력합성기는 -0.2dB의 입출력 손실과 각 포트 간 위상차는 평균 $2^{\circ}$로 양호한 특성을 보이고 있다. 제작한 SSPA모듈 실험 측정 결과 9~10GHz 주파수 대역에서의 Gain은 48.0dB 이상인 것을 확인하였으며, P(sat)=88.3W (49.46dBm) 이상, PAE=30.3% 이상임을 확인하였다. 본 논문에서 제작된 X-Band SSPA 모듈 성능 확인과 전력분배기/합성기 개선을 통해 향후 SSPA모듈에 대한 RF성능 개선에 많이 활용될 수 있을 것이다.

• ETRI Journal
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• 제31권1호
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• pp.68-70
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• 2009

In this letter, a parametric analysis of the Fresnel-field antenna measurement method is performed for a square aperture. As a result, the optimum number of Fresnel fields for one far-field point is guided as $M_{opt}=N_{opt}=D^2/{\lambda}R+5$, where D is the antenna diameter, ${\lambda}$ is the wavelength, and R is the distance between the source antenna and the antenna under test. For the aperture size 5 ${\leq}$ $L_x/{\lambda}$ ${\leq}$ 20, the tolerable distances for gain errors of 0.5 dB and 0.2 dB can be guided as $R_{0.5\;dB}$ ${\approx}$ $1.2Lx/{\lambda}$ and $R_{0.2\;dB}$ ${\approx}$ $2.0L_x/{\lambda}$, where $L_x$ is the lateral length of the square aperture. The tolerable distances for 20 ${\leq}$ $L_x/{\lambda}$ ${\leq}$ 200 are also proposed. This measurement guideline can be fully utilized when performing the Fresnel-field antenna measurement method.

• 한국통신학회논문지
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• 제22권11호
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• pp.2573-2584
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• 1997

본 연구에서는 Ca와 Sn이 치환된 YIG(Yttrium Iron Garnet)계 세라믹 자성체에서 Fe자리의 일부를 Al 치환한 자성체를 제조하고 스트립라인 서큘레이터를 설계한 후, 마이크로파대 서큘레이터를 구현하고 특성을 평가하였다. Al의 치환량에 따른 Ca와 Sn이 치환된 YIG 세라믹 자성체의 전기적, 자기적 및 마이크로파 특성을 측정한 결과, 마이크로파대에서 유전율($\varepsilon$')과 투자율($\mu$')은 각각 15.623, 0.972이었다. $Y_{2.4}Ca_{0.3}Sn_{0.3}Fe_{5-x}Al_xO_{12}$의 조성을 가진 자성체를 $1450^{\circ}C$에서 소결 제조한 결과, 페리자성 공명선폭($\Delta{H}$)이 42 Oe이고 포화자화가 487 G인 세라믹 자성체를 제조할 수 있었다. 3차원 유한요소법을 이용한 소프트웨어로 스트립라인 서큘레이터를 시뮬레이션하였으며, 중심주파수 1.9GHz 에서 삽입손실 0.8 dB, 반사손실 25 dB, 격리도 35 dB인 서률레이터를 설계하였다. 제조된 세라믹 자성체를 이용하여 중심주파수 1.9 GHz에서 삽입손실 0.869 dB, 반사손실 26.955 dB, 격리도 44.409 dB인 마이크로파용 서큘레이터를 제작할 수 있었다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2004년도 High Temperature Superconductivity Vol.XIV
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• pp.13-13
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• 2004

• 호남수학학술지
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• 제40권4호
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• pp.809-816
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• 2018

The aim of this research paper is to evaluate fifty double integrals invoving generalized hypergeometric function (25 each) in the form of $${{\int}^1_0}{{\int}^1_0}\;x^{{\gamma}-1}y^{{\gamma}+c-1}(1-x)^{c-1}(1-y)^{c+{\ell}}(1-xy)^{{\delta}-2c-{\ell}-1}{\times}_3F_2\[{^{a,\;b,\;2c+{\ell}+1}_{\frac{1}{2}(a+b+i+1),\;2c+j}}\;;{\frac{(1-x)y}{1-xy}}\]dxdy$$ and $${{\int}^1_0}{{\int}^1_0}\;x^{{\gamma}-1}y^{{\gamma}+c+{\ell}}(1-x)^{c+{\ell}}(1-y)^{c-1}(1-xy)^{{\delta}-2c-{\ell}-1}{\times}_3F_2\[{^{a,\;b,\;2c+{\ell}+1}_{\frac{1}{2}(a+b+i+1),\;2c+j}}\;;{\frac{1-y}{1-xy}}\]dxdy$$ in the most general form for any ${\ell}{\in}{\mathbb{Z}}$ and i, j = 0, ${\pm}1$, ${\pm}2$. The results are derived with the help of generalization of Edwards's well known double integral due to Kim, et al. and generalized classical Watson's summation theorem obtained earlier by Lavoie, et al. More than one hundred ineteresting special cases have also been obtained.