• 한국세라믹학회지
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• 제22권6호
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• pp.87-93
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• 1985

The hematite the magetite and the maghemite thin film were prepared by oxidation and reductino of the vaccum-evaporated iron thin film. Interre;atoms between film preparation process and the electrical properties were investigated. At room temperature the electrical conductivity of the iron the hematite the magnetite and the maghemite thin film were $1{\times}10^4\Omega^{-1}cm^{-1}$, 2{\times}10^{-5}\Omega^{-1}cm^{-1}$, $3{\times}10^{-5}\Omega^{-1}cm^{-1}$, and $4{\times}10^{-5}\Omega^{-1}cm^{-1}$, resp-ectively. The surface of each thin film was dense and homogeneous. At the temperature that the iron thin film was converted into the hematite thin film the electrical conductivity decreased rapidly and the electrical con-ductivity of the hematite thin film increased as temperature increased. The hematite thin film was reduced to the magnetite thin film in H2 atmosphere. The electrical conductivity decreased rapidly at the temperature that the maghemite thin film is formed by oxidation of the magnetite thin film and the electrical conductivity of the maghemite thin film increased as temperature increased.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.139-145
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• 2004

A numerical study of underexpanded jet and impingement on a wall mounted at various distances from the nozzle exit is presented. The 3-dimensional Navier-Stokes equations and $\kappa-\omega$ turbulence equations are solved. The grids are constructed as overlapped grid systems to examine the distance effect. The DADI method is applied to obtain steady-state solutions. To avoid numerical instability such as the carbuncle that sometimes accompany approximate Riemann solver, the HLLE+ scheme is employed for the inviscid flux at the cell interfaces. A goal of this work is to apply a number of two-equation turbulence models based on the $\omega$ equation to the impinging jet problem.

• 대한수학회지
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• 제32권1호
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• pp.17-31
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• 1995

A Lorentzian para-Sasakian manifold M$(\varphi, \zeta, \eta, g)$ (abr. LPS-manifold) has been defined and studied in [9] and [10]. On the other hand, para-Sasakian (abr. PS)-manifolds are special semi-cosympletic manifolds (in the sense of [2]), that is, they are endowed with an almost cosympletic 2-form $\Omega$ such that $d^{2\eta}\Omega = \psi(d^\omega$ denotes the cohomological operator [6]), where the 3-form $\psi$ is the associated Lefebvre form of $\Omega$ ([8]). If $\eta$ is exact, $\psi$ is a $d^{2\eta}$-exact form, the manifold M is called an exact Ps-manifold. Clearly, any LPS-manifold is endowed with a semi-cosymplectic structure (abr. SC-structure).

• 대한수학회보
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• 제49권4호
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• pp.737-748
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• 2012

The goal of this paper is to study the existence of non-trivial non-negative weak solution for the nonlinear elliptic equation: $$-div(h(x){\nabla}u)=f(x,u)\;in\;{\Omega}$$ with Dirichlet boundary condition in a bounded domain ${\Omega}{\subset}\mathbb{R}^N$, $N{\geq}3$, where $h(x){\in}L^1_{loc}({\Omega})$, $f(x,s)$ has asymptotically linear behavior. The solutions will be obtained in a subspace of the space $H^1_0({\Omega})$ and the proofs rely essentially on a variation of the mountain pass theorem in [12].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.110-111
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• 2006

In this paper, we investigated resistance characteristic of chalcogenide material for next generation ReRAM nonvolatile memory device with laser irradiation. A AES is used to test Ag doping ratio into a As-Ge-Se-S thin film. A sample resistance was observed in real time with He-Ne laser(632.8nm). As a result, resistance of thermal treated As-Ge-Se-S thin film was $500{\Omega}$ which is smaller than initial $1.3M{\Omega}$. A resistance of non-treated Ag/As-Ge-Se-S thin film was $200{\Omega}$ which is lower than $35M{\Omega}$.

• Korean Journal of Mathematics
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• 제21권4호
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• pp.401-419
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• 2013

Let $n{\geq}0$ be an arbitrary integer. We define the class of almost n-simply presented abelian p-groups. It naturally strengthens all the notions of almost simply presented groups introduced by Hill and Ullery in Czechoslovak Math. J. (1996), n-simply presented p-groups defined by the present author and Keef in Houston J. Math. (2012), and almost ${\omega}_1-p^{{\omega}+n}$-projective groups developed by the same author in an upcoming publication [3]. Some comprehensive characterizations of the new concept are established such as Nunke-esque results as well as results on direct summands and ${\omega}_1$-bijections.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.332.2-332.2
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• 2014

OLED 소자가 소형화됨에 따라 Flexible display를 넘어 Foldable display를 연구 중이며 동시에 신뢰성 및 수명이 중요시 되고 있다. 따라서 본 연구에서는 신뢰성 및 수명 평가에 대한 한 가지 방법으로 Bending test를 이용하여 소자의 Resistivity 변화를 측정하여 소자의 신뢰성을 확인 하여 보았다. Flexible substrate위에 Ag와 Al을 Cross bridge structure로 각각 증착한 후 bending 시간에 따른 Sheet resistance (Rsh)와 Resistivity (비저항)을 분석 하였다. 100시간 동안의 bending test결과 Ag전극의 Rsh는 $0.104{\Omega}$에서 $0.098{\Omega}$으로 5.67% 감소하였고 비저항은 5.70% 감소하였다. Al전극의 Rsh는 $0.091{\Omega}$에서 $0.063{\Omega}$으로 30.4% 감소하였고 비저항은 30.3% 감소하였다. Foldable에서는 저항 변화가 크게 되면 접히는 부분의 흐르는 전류가 많아지게 되어 소자의 저하를 발생시킨다. 저항변화가 거의 없다는 것은 물질의 안정성이 좋다고 할 수 있다. 실험 결과 Ag의 저항 변화가 Al보다 작으므로 Ag가 Flexible 관련 물질로 더 유용하다는 것을 확인 할 수 있다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.106-107
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• 2011

Organic Light Emitting Diode(OLED), Optical Photovotaic Device(OPV)와 같은 유기소자에서 전극으로 적용되어지고 있는 Indium Tin Oxide (ITO) 박막의 유연성을 향상시키기 위하여 중간층으로 투명도(~80%)와 전도도(~1000 S/cm)가 우수한 PEDOT:PSS(PH1000)을 적용하였다. PEDOT:PSS(PH1000)의 적용으로 인하여 ITO 박막의 유연성이 현저히 개선됨과 동시에 PEDOT:PSS(PH1000)의 우수한 전도도로 인하여 보다 얇은 ITO의 두께에서도 우수한 면 저항(25 ${\Omega}/{\square}$ ~ 220 ${\Omega}/{\square}$) 및 비저항(3.75E-4 ${\Omega}{\cdot}cm$ ~ 4.40E-4 ${\Omega}{\cdot}cm$)의 값을 측정하였다.

• 대한수학회논문집
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• 제34권3호
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• pp.743-755
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• 2019

For every inverse semigroup S with subsemigroup E of idempotents, necessary and sufficient conditions are obtained for the weighted semigroup algebra $l^1(S,{\omega})$ and its second dual to be $l^1(E)$-module amenble. Some results for the module Arens regularity of $l^1(S,{\omega})$ (as an $l^1(E)$-module) are found. If S is either of the bicyclic inverse semigroup or the Brandt inverse semigroup, it is shown that $l^1(S,{\omega})$ is module amenable but not amenable for any weight ${\omega}$.

• 대한수학회논문집
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• 제38권3호
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• pp.787-805
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• 2023

Let (Ω, µ) be a measure space and {τ_α}_α∈Ω be a normalized continuous Bessel family for a finite dimensional Hilbert space 𝓗 of dimension d. If the diagonal ∆ := {(α, α) : α ∈ Ω} is measurable in the measure space Ω × Ω, then we show that $$\sup\limits_{{\alpha},{\beta}{\in}{\Omega},{\alpha}{\neq}{\beta}}\,{\mid}{\langle}{\tau}_{\alpha},\,{\tau}_{\beta}{\rangle}{\mid}^{2m}\,{\geq}\,{\frac{1}{({\mu}{\times}{\mu})(({\Omega}{\times}{\Omega}{\backslash}{\Delta})}\;\[\frac{{\mu}({\Omega})^2}{\({d+m-1 \atop m}\)}-({\mu}{\times}{\mu})({\Delta})\],\;{\forall}m{\in}{\mathbb{N}}.$$ This improves 48 years old celebrated result of Welch [41]. We introduce the notions of continuous cross correlation and frame potential of Bessel family and give applications of continuous Welch bounds to these concepts. We also introduce the notion of continuous Grassmannian frames.