• 대한수학회논문집
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• 제31권1호
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• pp.101-113
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• 2016

In this article, we considered the stability of the following (${\alpha}$, ${\beta}$, ${\gamma}$)-derivation $${\alpha}D[x,y]={\beta}[D(x),y]+{\gamma}[x,D(y)]$$ and homomorphisms associated to the quadratic type functional equation $$f(kx+y)+f(kx+{\sigma}(y))=2kg(x)+2g(y),\;x,y{\in}A$$, where ${\sigma}$ is an involution of the Lie $C^*$-algebra A and k is a fixed positive integer. The Hyers-Ulam stability on unbounded domains is also studied. Applications of the results for the asymptotic behavior of the generalized quadratic functional equation are provided.

• 대한수학회보
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• 제54권4호
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• pp.1331-1336
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• 2017

Assume that R is a commutative Noetherian ring with non-zero identity, a is an ideal of R, X is an R-module, and t is a non-negative integer. In this paper, we present upper bounds for the injective dimension of X in terms of the injective dimensions of its local cohomology modules and an upper bound for the injective dimension of $H^t_{\alpha}(X)$ in terms of the injective dimensions of the modules $H^i_{\alpha}(X)$, $i{\neq}t$, and that of X. As a consequence, we observe that R is Gorenstein whenever $H^t_{\alpha}(R)$ is of finite injective dimension for all i.

• 품질경영학회지
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• 제22권2호
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• pp.89-97
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• 1994

We consider the linear calibration model: $y_1={\alpha}+{\beta}x_i+{\sigma}{\varepsilon}_i$, i = 1, ${\cdots}$, n, $y={\alpha}+{\beta}x+{\sigma}{\varepsilon}$ where ($y_1$, ${\cdots}$, $y_n$, y) stands for an observation vector, {$x_i$} fixed design vector, (${\alpha}$, ${\beta}$) vector of regression parameters, x unknown true value of interest and {${\varepsilon}_i$}, ${\varepsilon}$ are mutually uncorrelated measurement errors with zero mean and unit variance but otherwise unknown distributions. On the basis of simple small-sample low-noise approximation, we introduce a new method of comparing the mean squared errors of the various competing estimators of the true value x for finite sample size n. Then we show that a class of estimators including the classical and the inverse estimators are consistent and first-order efficient within the class of all regular consistent estimators irrespective of type of measurement errors.

• 한국주조공학회지
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• 제19권6호
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• pp.472-483
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• 1999

The effects of rapid solidification and Cr addition to the microstructure variations of the rapid solidified Ti-48Al-xCr(X = 2,4,6) alloys have been investigated using X-ray diffractometry, optical microscopy, scanning electron microscopy and transmission electron microscopy. The segregated coarse ${\gamma}$ phase was eliminated and the microstructure was refined by rapid solidification of the cooling rate of $10^4-10^6\;^{\circ}C/sec$. The lattice parameters and tetragonality of ${\gamma}$ phase decrease with the increase Cr content and by the rapid solidification. Non-equilibrium phase ${\alpha}$ remains at room temperature condition, which would be resulted from the restriction of phase transformation ${\alpha}$ to ${\alpha}_2+{\gamma}$.

• 호남수학학술지
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• 제31권4호
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• pp.505-513
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• 2009

Let {$X_k;k{\in}N^d$} be centered and identically distributed random field which is asymptotically negative dependent in a certain case. In this note we prove that for $p{\alpha}$ > 1 and ${\alpha}$ > ${\frac{1}{2}}$ $E{\mid}X_1{\mid}^p(log^+{\mid}X_1{\mid}^{d-1})$ < ${\infty}$ if and only if ${\sum}_n{\mid}n{\mid}^{p{\alpha}-2}P$($max_{1{\leq}k{\leq}n{\mid}S_k{\mid}}$ > ${\epsilon}{\mid}n{\mid}$) < ${\infty}$ for all ${\epsilon}$ > 0, where log$^+$x = max{1,log x}.

• Journal of Radiation Protection and Research
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• 제10권1호
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• pp.14-28
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• 1985

고순도 물질의 $K_{\alpha}$형광 X-선을 이용하여 100 keV 이하에서의 단색 Photon 선원을 개발하였다. 단색 Photon은 방사선 측정기기의 교정에 매우 유용한 것으로 얇은 금속박막의 Radiator에 제동복사선을 조사하여 얻을 수 있다. 본 실험에서는 $_{47}Ag,\;_{50}Sn,\;_{68}Er,\;_{70}Yb,\;_{82}Pb$, 등의 Radiator를 사용하여 20 keV 에서 80 keV의 범위에서 단색 Photon을 얻어내어 고순도 HpGe LEPS로 0.64-0.94에 이르는 단색도를 얻어내었고 600cc 얇은창이온전리함을 사용하여 8.3mR/h 에서 232. 5mR/h에 이르는 선량률을 얻어 내였다.

• 생명과학회지
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• 제21권4호
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• pp.481-485
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• 2011

T0901317은 핵수용체 전사인자인 liver X receptor (LXR, NR1H2/3)의 강력한 합성 리간드이다. 그러나, T0901317은 farnesoid X receptor (FXR, NR1H4)와 pregnane X receptor (PXR, NR1I2)에 대해 작용물질(agonist) 로, androgen receptor (AR, NR3C4)와 rertinoid-related orphan receptor-${\alpha}$ (ROR-${\alpha}$, NR1F1)에 대해 길항제(antagonist)로 작용하여, LXR외에 적어도 다른 4종의 핵수용체에 대해 그 활성을 조절한다고 보고되었다. 우리는 T0901317이 또 다른 핵수용체인 constitutive androstane receptor (CAR, NR1I3)에 대해 저해제로 기능함을 확인 하였다. CAR는 이미 T0901317에 의해 기능이 조절된다고 알려진 PXR, FXR, LXR과 더불어 간에서 생체이물과 콜레스테롤의 대사작용에 중요한 역할을 하므로 T0901317에 의해 CAR의 활성이 조절된다는 사실은, 간세포에서 T0901317을 이용한 실험 결과를 해석할 때 세포 내에 이미 존재하는 이들 핵수용체 단백질의 영향을 고려하여 주의깊게 해석해야 함을 의미한다.

• 한국주조공학회지
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• 제31권6호
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• pp.362-365
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• 2011

In the present work, the corrosion properties of Mg-xSn (x = 1, 3, 5, 7 and 9 wt.%) alloys have been investigated. Potentiodynamic polarization and immersion tests were carried out in 3.5% NaCl solution of pH 7.2 at room temperature to measure the corrosion properties of Mg-xSn (x = 1, 3, 5, 7 and 9 wt.%) alloys. With increase of the Sn contents, the volume fraction of the $Mg_2Sn$ phase was increased. The corrosion rate of Mg-xSn alloys was increased up to 7 wt.%Sn and decreased above 9 wt.%Sn. Initiation of galvanic site during immersion mainly occurred at Mg/$Mg_2Sn$ interface and propagation went into ${\alpha}$-Mg. For this reason, corrosion properties of Mg-xSn (added from 1 wt.%Sn to 7 wt.%Sn alloys) alloys are decreased because the galvanic site was increased with increasing Sn addition. In Mg-9wt.%Sn alloy, however, the corrosion site were changed from Mg/$Mg_2Sn$ interface to ${\alpha}$-Mg/$M_2Sng$ interface in lamellar structure. Preferentially corrosion of ${\alpha}$-Mg/$M_2Sn$ interface in lamellar structure impeded corrosion propagation went into ${\alpha}$-Mg.

• 한국자기학회지
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• 제5권1호
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• pp.21-26
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• 1995

비화학양론 조성의 니켈-아연 페라이트 소결체 시편에서 투자율과 유전율을 체계적으로 변화 시킴에 따라 전파흡수특성에 미치는 영향을 조사하였다. ${(Ni_{0.5}Zn_{0.5}O)}_{1-x}(Fe_{2}O_{3})_{1+x}$ 시편은 일반적인 세라믹 제조공정에 의해 제조 하였다. 본 연구에서는 니켈-아연 페 라이트에서 ${\alpha}-Fe_{2}O_{3}$ 함량을 변화시킴에 따라 복수투자율과 복소유전율의 조절 방안 을 조사하였다. 철과잉량의 효과는 유전상수 증가였으며 철결핍량의 효과는 ${\mu}_{r}"$ 감소이었다. 니켈-아연 페라이트에서 ${\alpha}-Fe_{2}O_{3}$ 함량 변화에 따라 정합주파수와 정합두께 조절이 가능함을 제시하였다.

• Bulletin of the Korean Chemical Society
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• 제11권1호
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• pp.49-54
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• 1990

The gas-phase thermolysis reactions of ${\alpha}$- and ${\beta}$-methylated ethyl formates, Y = $CH-X-CHR_1CH_2R_2$ where X = Y = O or S and $R_1\;=\;R_2$ = H or $CH_3$, are investigated theoretically using the AM1 method. The experimental reactivity order is reproduced correctly by AM1 in all cases. The thermolysis proceeds through a six-membered cyclic transition state conforming to a retro-ene reaction, which can be conveniently interpreted using the frontier orbital theory of three-species interactions. The methyl group substituted at $C_{\alpha}\;or\;C_{\beta}$ is shown to elevate the ${\pi}$-HOMO of the donor fragment (Y = C) and depress the ${\sigma}^{\ast}$-LUMO of the acceptor fragment ($C_{\beta}$-H), increasing the nucleophilicity of Y toward ${\beta}$-hydrogen which in turn increases the reactivity. The two bond breaking processes of the $C_{\alpha}$-X and $C_{\beta}$-H bonds are concerted but not synchronous so that the reaction takes place in two stages as Taylor suggested. The initial cleavage of $C_{\alpha}$-X is of little importance but the subsequent scission of $C_{\beta}$-H occurs in a rate determining stage.