• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.197-197
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• 1999

Gate oxide 의 두께 감소는 gate의 캐패시턴스를 증가시켜 트랜지스터의 속도를 빠르게 하며, 동시에 저전압 동작을 가능하게 하기 때문에 gate oxide 두께는 MOS 공정 세대가 진행되어감에 따라 계속 감소할 것이다. 이러한 얇은 산화막은 device design에 명시된 두께의 특성을 나타내야 한다. Gate oxide의 두께가 작아질수록 gate oxide와 crystalline silicon간의 계면효과가 박막의 두께의 결정에 심각한 영향을 주기 때문에 정확한 두께 계측이 어렵다. 이러한 영향과 계측방법에 따라서 두께 계측의 차이가 나타난다. XTEM은 사용한 parameter에, Ellipsometer는 refractive index에, MEIS(Medium) Energy Ion Scattering)은 에너지 분해능에, Capacitor-Voltage 측정은 depletion effect에 의해 영향을 받는다. 우리는 계면의 원자분해능 분석에 통상 사용되어온 High Resolution TEM을 이용하여 약 30~70$\AA$ SiO2층의 두께와 계면 구조에 대한 분석을 하여 이를 MEIS와 0.015nm의 고감도를 가진 SE(Spectroscopy Ellipsometer), C-V 측정 결과와 비교하여 가장 좋은 두께 계측 방법을 찾고자 한다.

• 대한기계학회논문집
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• 제19권11호
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• pp.2995-3002
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• 1995

The cooling problem of the hot internal pipe flow has been investigated. Simultaneous conduction, convection, and radiation were considered with azimuthally varying convective heat loss at the pipe wall. A complex, nonlinear integro-differential radiative transfer equation was solved by the discrete ordinates method (or called S$_{N}$ method). The energy equation was solved by control volume based finite difference technique. A parametric study was performed by varying the conduction-to-radiation parameter, optical thickness, and scattering albedo. The results have shown that initially the radiatively active medium could be more efficiently cooled down compared with the cases otherwise. But even for the case with dominant radiation, as the medium temperature was lowered, the contribution of conduction became to exceed that of radiation.n.

• Current Applied Physics
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• 제18권11호
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• pp.1338-1344
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• 2018

Band parameters and superconductivity of yttrium hypocarbide ($Y_2C$) have been investigated. The computations are performed using first-principles pseudopotential method within a generalized gradient approximation. The equilibrium lattice parameters have been determined and compared with experiment. Moreover, the material of interest is found to be stiffer for strains along the a-axis than those along the c-axis. A band-structure analysis of $Y_2C$ implied that the latter has a metallic character. The examination of Eliashberg Spectral Function indicates that Y-related phonon modes as well as C-related phonon modes are considerably involved in the progress of scattering of electrons. By integrating this function, the value of the average electron-phonon coupling parameter (${\lambda}$) is found to be 0.362 suggesting thus that $Y_2C$ is a weak coupling Bardeen-Copper-Schrieffer superconductor. The use of a reasonable value for the effective Coulomb repulsion parameter (${\mu}^*=0.10$) yielded a superconducting critical temperature $T_c$ of 0.59 K which is comparable with a previous theoretical value of 0.33 K. Upon compression (at pressure of 10 GPa) ${\lambda}$ and $T_c$ are increased to be 0.366 and 0.89 K, respectively, showing thus the pressure effect on the superconductivity in $Y_2C$. The spin-polarization calculations showed that the difference in the total energy between the magnetic and non-magnetic $Y_2C$ is weak.

• 대한전자공학회논문지SD
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• 제41권11호
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• pp.15-20
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• 2004

본 논문에서는 초고주파나 밀리미터파 대역에서 코프래너 도파로 구조로부터 S-파라메타를 이용하여 유효유전상수를 도출하는 간단한 방법을 제시하였다. 이 방법은 특성임피던스 Z/sub o/와 전송선 길이 ℓ로 주어진 전송선이 주파수가 변화함에 따라 나타나는 S/sub 11/ 값으로부터 βℓ =nπ 에서 극한적으로 바뀌는 것을 이용하여 유효유전상수 ε/sub eff/를 도출하는 기법이다. ε/sub r/=3.38의 Rogers 4003/sup TM/ 기판 위에서 실험적으로 얻어진 유효유전상수 값은 2.042로 나타났으며, 기존의 공식으로부터 얻어진 ε/sub eff/ 값은 -3.4%에서 8% 범위의 오차를 보여 주었다. 코프래너 도파로 구조의 유효유전상수 값이 간단한 측정 방법으로 뿐만 아니라 제작된 회로 구조 위에서 직접 측정될 수 있어, 복잡한 회로 구조를 지닌 다른 유전체 재질의 기판 위에서도 측정이 보다 정확하고 간단하게 이루어 질 수 있음을 보여 주었다.

• 대한전자공학회논문지
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• 제13권1호
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• pp.16-22
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• 1976

비가역성 소자인 광대역 마이크로스트립 Y형 써어클레이티는 Bosma의 Green함수를 적용하여 Rosenbaum이 해석하띠 산란행렬로 실제적 이론치인 삽입손실, 아이솔궤이션을 구하였다. 중요한 설계 변수로는 전봉선과 접합각인 ${\psi}$이고 이를 알맞게 선택하여 광대역 정합을 이루었다. 또한 Y형 써어쿨레이터의 입력칟지던스를 구하였다. 제작시 실표반학은 이론치보다 7.5% 적은것을 요하며 5-11GHz에서 V.S.W.R.은 1.5이하였고 최대 삽입손집은 0.5dB, 아이슬레이션은 15dB 이상이었다.

• Ocean and Polar Research
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• 제37권4호
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• pp.333-340
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• 2015

The contrast (fish body to medium ratio) of density and sound speed were measured to estimate acoustic scattering from small juvenile cod (Gadus macrocephalus) with the Kirchhoff-Ray Mode backscatter model. The density contrast was measured by the density-bottle method and the sound speed contrast was estimated by the time of flight method. The results revealed that the measured density contrasts of juvenile cod varied between 1.003 and 1.029 (mean = 1.014, S.D. = 0.01). On the other hand, sound speed contrasts varied between 1.039 and 1.041 (mean = 1.041, S.D. = 0.001). The relationship between averaged target strength (TS) and total length (TL) established by the model were <$TS_{38kHz}$> = 20log(TL) - 68.8 and <$TS_{38kHz}$> = 20log(TL) - 69.4, respectively.

• Nuclear Engineering and Technology
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• 제33권1호
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• pp.46-61
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• 2001

The neutron cross sections of $^{160}$ Dy, $^{161}$ Dy, $^{162}$ Dy, $^{l63}$Dy, and $^{164}$ Dy have been evaluated in the resonance region of which upper energy is set to several tens of keV. The cross sections are formulated with resonance parameters in the energy region under consideration. In the resolved resonance region, the positive-energy resonance parameters were adopted from the BNL compilation published in 1984 with slight, if any, modifications. A bound level resonance for each isotope except $^{162}$ Dy was invoked to reproduce the reference 2200 m/s cross sections and the bound coherent scattering length. Subsequently, the statistical behavior of the resolved resonance parameters was analyzed, and thus obtained s-wave average parameters were adopted in the unresolved resonance region. In addition, recent measurements of the capture cross sections in the unresolved region were taken into account in adjusting the average resonance parameters for high orbital angular momentum resonances. The present evaluation resulted in large improvements in the cross sections over the ENDF/B-Vl release 6.6.

• 한국자기학회지
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• 제14권3호
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• pp.99-104
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• 2004

자기 터널 접합(Magnetic Tunnel Junction, MTJ)의 플라즈마 산화시간과 열처리 온도에 따른 자기저항(Tunneling Magnetoresistance, TMR) 온도의존특성을 연구하였다. 플라즈마 산화시간을 30$_{s}$ 70$_{s}$ 까지 10$_{s}$ 간격으로 변화시켜 측정한 결과, 산화시간 50초에서 상온에서 25.3%의 가장 높은 TMR 비를 얻었다. 스핀 분극도 $P_{0}$ 스핀파 지수(spin wave parameter) $\alpha$를 구한 결과, 산화시간 50$_{s}$ 에서 40.3%의 가장 높은 스핀 분극도와 가장 낮은 온도 의존 특성인 (10$\pm$4.742)${\times}$$10^{-6}$ $K^{－1.5}$스핀파 지수(spin wave parameter) $\alpha$값을 얻었다. 그리고 온도별 열처리 결과 175$^{\circ}C$에서 TMR비가 25.3%에서 27.5%까지 증가하였으며 스핀파 지수는 (10$\pm$0.719)${\times}$$10^{-6}$ K $^{－1.5}$ 까지 감소하여 온도의존도가 감소하였다.

• 전기학회논문지P
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• 제66권4호
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• pp.242-246
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• 2017

In this study, it was investigated about optical simulation in high brightness and high uniformity general lighting using glass light guide plate. And we adopt edge-light emission type light plate. Edge-light type lighting has been used LCD application, especially note PC or smart phone backlight unit. Because it had the good properties such as slim shape and light weight. We thought this type was suitable for general lighting application such as wall attached type or ceiling mount type. But many of edge-light type lighting had problems. It called slanted output light rays. That was main key parameter how could control the direction of output light rays. We investigated the solution of this problems, using ray tracing method, we recognized the major fact of the solution relied on the geometric structure of diffusing dot shape. We set the conditions of aspect ratio in diffusing dot shape such as 0.5 to 1. And, at first, we designed diffusing dots shape based on the results of optical simulation and made specimen. as above condition, and acquired good result in confirming dots shape such as the value of the output rays's peak angle was around 75 degrees. And good light distribution characteristics were measured by slated spectro-radiometer. It was shown that the effective ways of designing light distribution characteristics using optical simulation such as ray tracing linear method for making general lighting using glass light guide plate.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.140.1-140.1
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• 2015

Currently, As Plasma application is expanded to the industrial and medical industrial, Low temperature plasma characteristics became important. Especially in Medical industrial, Low temperature plasma directly adapted to human skin, so their plasma parameter is important. One of the plasma parameters is electron density, some kinds of method to measuring electron density are Thomson scattering spectroscopy and Millimeter-wave transmission measurement. But most methods is expensive to composed of experiment system. Heterodyne interferometer system is cheap and simple to setting up, So we tried to measuring electron density by Laser heterodyne interferometer. To measuring electron density at atmospheric pressure, we need to obtain the phase shift signal. And we use a heterodyne interferometer. Our guiding laser is Helium-Neon laser which generated 632 nm laser. We set up to chopper which can make a laser signal like a pulse. Chopper can make a 4 kHz chopping. We used Needle jet as Ne plasma sources. Interference pattern is changed by refractive index of electron density. As this refractive index change, phase shift was occurred. Electron density is changed from Townsend discharge's electron bombardment, so we observed phenomena and calculated phase shift. Finally, we measured electron density by refractive index and electron density relationship. The calculated electron density value is approximately 1015~1016 cm-3. And we studied electron density value with voltage.