• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.38-38
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• 2003

PTO/PZO 초격자 박막은 박막 계면에 응력이 발생하여 기존의 박막처럼 size effect가 적용되지 않고 두께가 감소해도 높은 유전상수를 갖는다. Antiferroelectric PbZrO$_3$(PZO)와 ferroelectric PbTiO$_3$(PTO)를 적층 성장시킨 초격자는 400도에서 성장한 (100) Pt/SiO$_2$기판 위에 rf magnetron sputtering으로 증착하였다. PTO/PZO의 증착 주기는 30(PTO $_{4unti cells}$/PZO $_{4unti cells}$) 에서 1(PTO $_{125unti cells}$/PZO $_{125unti cells}$)까지 두께의 변화를 주어 준비했고 초격자 박막의 전체두께는 100nm로 고정시켰다. XRD결과, PTO/PZO는 주기에 따라 초격자의 특성인 main peak과 satellite peak을 관찰 할 수 있었다. 초격자의 주기가 감소함에 따라 2$\theta$값이 증가하고 평균 d 값이 감소되면서 PTO층에 뒤틀림이 증가하였다. PTO층의 뒤틀림 증가로 인해 superlattice의 주기가 증가함에 따라 초격자의 유전율이 증가하였고 강유전성이 향상되었다.향상되었다.

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.228-233
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• 2005

Langmuir-Blodgett(LB) technique can speak the best candidate of the future molecular electronic devices. But, precursor as molecular ultrathin film devices require the bulk property that are influenced by the molecular orientation. So, this device is one of current interest in molecular electronic device development of new materials. In this study, quantitative evaluation of molecular orientation in LB films of polyamic acid alkylamine salt was performed analysis experiment comparing the absorption or transmission intensity of the FT-IR spectrometer and reflection or absorption spectra with UV-visible absorption spectra. It could find that the polar angle(${\theta}$) of the dipole moment appears in about $68^{\circ}$ and the tilting angle of the alkyl chain is about $11.5^{\circ}$.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.117-120
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• 2005

This study of thermal convection uses the following geometry: a horizontal layer of fluid heated from below of solid lid at bottom and cooled from above. A variety range of thermal conductivity ratio, $\kappa$ is considered to investigate the interface temperature, $\theta_{i}$ between solid and fluid region. Periodic boundary conditions are employed in the horizontal direction to allow for lateral freedom for the convection cells. A two-dimensional solution for unsteady natural convection is obtained, using an accurate and efficient Chebyshev spectral multi-domain methodology, for different effective Rayleigh numbers, $Ra_{eff}$ varying over the range of $10^{4}\;to\;10^{7}$ in which the effective Rayleigh number is defined as $Ra{\times}<\overline{T}_{i}>$.

• Bulletin of the Korean Mathematical Society
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• v.48 no.2
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• pp.413-426
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• 2011

Two types of new methods with variable time steps are proposed in order to valuate binary options efficiently. Type I changes adaptively the size of the time step at each time based on the magnitude of the local error, while Type II combines two uniform meshes. The new methods are hybrid finite difference methods, namely starting the computation with a fully implicit finite difference method for a few time steps for accuracy then performing a ${\theta}$-method during the rest of computation for efficiency. Numerical experiments for standard European vanilla, binary and American options show that both Type I and II variable time step methods are much more efficient than the fully implicit method or hybrid methods with uniform time steps.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1805-1821
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• 2016

In this paper, we are concerned with the nonlinear elliptic equations of the p(x)-Laplace type $$\{\begin{array}{lll}-div(a(x,{\nabla}u))+{\mid}u{\mid}^{p(x)-2}u={\lambda}f(x,u) && in\;{\Omega}\\(a(x,{\nabla}u)\frac{{\partial}u}{{\partial}n}={\lambda}{\theta}g(x,u) && on\;{\partial}{\Omega},\end{array}$$ which is subject to nonlinear Neumann boundary condition. Here the function a(x, v) is of type${\mid}v{\mid}^{p(x)-2}v$ with continuous function $p:{\bar{\Omega}}{\rightarrow}(1,{\infty})$ and the functions f, g satisfy a $Carath{\acute{e}}odory$ condition. The main purpose of this paper is to establish the existence of at least three solutions for the above problem by applying three critical points theory due to Ricceri. Furthermore, we localize three critical points interval for the given problem as applications of the theorem introduced by Arcoya and Carmona.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.53.1-56
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• 2000

Langmuir-Blodgett(LB) technique is the best candidate for the future molecular electronic devices. But, these molecular thin film devices require the bulk properties that are influenced by the molecular orientations. So, this is of current interest in molecular electronic device fabrications of new materials. In this study, quantitative evaluation of molecular orientation in LB films of PAAS was performed by comparing the absorption intensities of the FT-IR transmission and reflection-absorption spectra and the polarized UV/visible absorption spectra. It was found that the polar angle($\theta$) of the dipole moment is about 68$^{\circ}$and the tilting angle of the alkyl chain is about $11.5^{\circ}$ .

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.111-112
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• 2017

This paper presents a novel three-port converter for the OnBoard Charger of Electric Vehicles by using an impedance control network. The proposed concept is suitable for charging a main battery and an auxiliary battery of an electric vehicle at the same time due to its power handling capability of the converter without additional switches. The power flow is managed by the phase angle (${\Theta}$) between the ports whereas voltage at each port is controlled by the asymmetric duty cycle and the phase shift (${\Phi}$) between the inverter lags controlled by the impedance control network. The proposed system has a capability of achieving zero voltage switching (ZVS) and zero current switching (ZCS) at all the switches over the wide range of input voltage, output voltage and output power. The feasibility of the proposed system is verified by the PSIM simulation.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.661-663
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• 1998

합병 문제는 크기가 각각 l, m(l+m=n)인 두 개의 정렬된 리스트를 하나의 정렬된 리스트로 만드는 문제로 정렬 문제와 그래프 문제 등과 같은 여러 가지 문제를 해결하는데 필요한 중요한 문제이다. p($\theta${{{{ LEFT ( {λlogp} over {log(λ+1)} RIGHT ) }}}}).

• Journal of Korean Society for Quality Management
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• v.27 no.3
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• pp.79-93
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• 1999

The common accelerated life test(ALT) consists of test methods applying a constant stress, higher than the use condition stress, to items. There we, however, situations for which a progressive stress ALT, in which the stress on a test item is continuously increased with time, Is more convenient to perform testing and simpler in analyzing data than a constant stress ALT. When a product under constant stress s follows a Weibull distribution with parameters $\theta$(5) and $\beta$, maximum likelihood(ML) estimators of parameters involved in the model are obtained and their asymptotic distributions are derived under stress bounded ramp tests in which the stress is increased linearly from use condition stress to the stress upper bound. The optimum test plans are also found which minimize the asymptotic variance of the ML estimator of the log mean life at design constant stress. For selected values of the design parameters, tables useful for finding optimal test plans are given. The effect of the pre-estimates of design parameters is studied.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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• pp.321-324
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• 2013

In this study, The RF magnetron sputter and evaporator was on glass substrates 30 mm ${\times}$ 30 mm OMO multilayer thin film structure is applied to the low-e. Structural and optical properties, a thin film was produced, the variable was placed into a variable deposition time of the oxide layer. According to the XRD measurement results there is no peak that satisfies the Bragg's law ($2dsin{\theta}=n{\lambda}$) which confirmed that it is an amorphous structure. RMS value of the results of the AFM measurement, has a roughness of less than 2 nm. transmittance measurements results, visible light region an average 80%, IR region 40% showed.