• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1447-1449
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• 1998

The c-axis orientation plays a very important role in controlling the main parameters of the perpendicular magnetic recording media, such as perepndicular magnetic anisotropy field $H_{K{\bot}}$, the ratio of coercive force $H_{C{\bot}}/H_{C//}$, the recording density $D_{50}$, and the dispersion of the c-axis orientation $\Delta\theta_{50}$, which is quite important for the performance as perpendicular recording media, as well as the magnetic properties of the film. In this study, the essential process requirement for preparing the Co-Cr films with the superior c-axis orientation, the dependence of $\Delta\theta_{50}$ and the magnetic properties on the film thickness $\delta$, and the effect of underlayer on the dispersion of c-axis orientation have been investigated for both the FTS and DCM system.

• 대한기계학회논문집B
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• 제25권12호
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• pp.1766-1775
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• 2001

A theoretical analysis on the heat and mass transfer in an evaporative cooler is presented in this work. The evaporative cooler is modeled as a channel filled with porous media the interstitial surface of which is covered by thin water film. Assuming that the Lewis number is unity and the water vapor saturation curve is linear, exact solutions to the energy and vapor concentration equations are obtained. Based on the exact solutions, the characteristics of the heat and mass transfer in the evaporative cooler are investigated. The comparison of the cooling performance between the evaporative cooler and the usual sensible heat exchanger is also carried out. Obviously, the evaporative heat exchanger shows better cooling performance than the sensible heat exchanger. This is due to the latent heat of water vaporization, which results in apparent increases both in the interstitial heat transfer coefficient and the specific heat of the air stream in the evaporative cooler.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.124-127
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• 2005

Rewritable optical memory devices such as an CD-RW and DVD+RW are data storage media, which take advantage of the different optical properties in the amorphous and crystalline states of phase change materials. The switching property, structural transformation, transformation kinetics and chemical bindings of $Ge_xSb_{100-x}$($6{\le}x{\le}$34) were studied to investigate the feasibility of applying $Ge_xSb_{100-x}$ alloys in optical memory. The $Ge_xSb_{100-x}$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, inductively coupled plasma atomic emission spectrometer (ICP-AES) and atomic force microscopy (AEM). Optimum fiim composition of $Ge_xSb_{100-x}$ was studied and its minimum time fur laser induced crystallization and optical contrast fur phase transition was performed. These results might be correlated with the binding energies between Ge and Sb, and indicate that $Ge_xSb_{100-x}$ have an potential far optical memory applications.

• 한국자기학회지
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• 제5권2호
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• pp.134-139
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• 1995

DC magnetron 스파터링 방법으로 $(Co_{93}Cr_{7})-P-Ni$ 계 수평 자기 기록용 박막을 제조하였다. $(Co_{93}Cr_{7})-P-Ni$ 의사 삼원계(pseudo-ternary) 박막의 Ni 및 P의 함량 변황 따른 자기적 특성의 변화를 조사하였다. 박막의 조성을 조절함으로써 최대 1500 Oe의 보자력을 얻을 수 있었다. P 첨가에 따른 보자력 향상의 원인으로는 면내 이방성(in-plane anisotropy) 향상, 입자 크기의 변화, P 성분의 입계편석에 따른 입자간의 decoupling 등을 들 수 있다. 또한 TEM으로 미세 구조를 관찰한 결과 P 가 첨가되면 입자의 크기가 작아지면서 입자간의 자기적 decoupling이 일어남을 알 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.889-892
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• 2009

We have developed a practical printing technology for the gate electrode of organic thin film transistors(OTFTs) by combining screen-printing with wet-etching process using nano-silver ink as a conducting material. The screen-printed and wet-etched Ag electrode exhibited a minimum line width of ~5 um, the thickness of ~65 nm, and a resistivity of ${\sim}10^{-6}{\Omega}{\cdot}cm$, producing good geometrical and electrical characteristics for gate electrode. The OTFTs with the screen-printed and wet-etched Ag electrode produced the saturation mobility of $0.13cm^2$/Vs and current on/off ratio of $1.79{\times}10^6$, being comparable to those of OTFT with the thermally evaporated Al gate electrode.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.247-250
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• 2007

Flexible media such as the paper, the film, etc. are thin, light and very flexible. They behave in geometrically nonlinear. Any of small force makes large deformation. So we must including aerodynamic effect when its behavior is predicted. Thus, it becomes fully coupled fluid-structure interaction(FSI) problem. In FSI problems, where the fluid mesh near the structure undergoes large deformations and becomes unacceptably distorted, which drive the time step to a very small value for explicit calculations, the arbitrary Lagrangian-Eulerian(ALE) methods or rezoning are used to create a new undistorted mesh for the fluid domain, which allows the calculations to continue. In this paper, FE sheet model considering geometric nonlinearity is formulated to simulate the behavior of the flexible media. Aerodynamic force to the media by surrounding air is calculated by solving the incompressible Navier-Stokes equations. Q2Q1(Taylor-Hood) element which means biquadratic for velocity and bilinear for pressure is used for fluid domain. Q2Q1 element satisfies LBB condition and any stabilization technique is not needed. In this paper, cantilevered sheet in the viscous incompressible Navier-Stokes flow is simulated to check the mesh motion and numerical integration scheme, and then falling paper in the air is simulated and the effects of some representative parameters are investigated.

• 한국자기학회지
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• 제11권4호
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• pp.168-172
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• 2001

Sol-gel법을 이용하여 Co$_{0.9}$Zn$_{0.1}$Fe$_2$O$_4$ 박막을 제조하였다. 성장한 박막의 구조 및 자기적 성질에 관하여 x선 회절분석기 (XRD), atomic force microscopy(AFM) 및 Auger electron spectroscopy(AES), 진동시료자화측정기 (VSM)을 이용하였다. Co-Zn 페라이트 박막의 경우, 400 $^{\circ}C$ 이상의 열처리 온도에서 단일상의 spinel 구조만을 가지고 있으며, 아무런 방향성이 없이 성장함을 나타내고 있다. 열처리 온도가 600 $^{\circ}C$ 이하에서 성장된 박막 표면의 거칠기는 3 nm 이하였으며, 형성된 입자의 크기는 약 40nm이하임을 알 수 있었다. 또한, 40$0^{\circ}C$에서 열처리한 경우 기판에서 Si이 Co-Zn 페라이트 박막내로 확산이 거의 나타나지 않았으나, 870 $^{\circ}C$에서 열처리한 경우 계면에서 기판과 박막의 상호 확산을 확인할 수 있었다. 제작한 박막은 외부 자기장의 방향과는 무관한 등방성의 자기적 특성을 보이며, 최대 보자력은 600 $^{\circ}C$에선 열처리한 자성박막이 약 1,900 Oe을 가짐을 알 수 있었다.있었다.

• 한국진공학회지
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• 제15권2호
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• pp.173-179
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• 2006

Pulsed laser deposition 방법으로 증착한 $PbZr_{0.3}Ti_{0.7}O_{3}$ (PZT)박막의 구조적, 전기적 성질에 대한 연구를 하였다. PZT 박막은 $LaAlO_3$ 기판위에 동일한 조건으로 증착된 $LaMnO_3$ (LMO) 산화물을 하부 전극으로 하여 증착시간을 변화시키며 증착하였다. High-resolution x-ray diffraction 결과를 통해 LMO 하부 전극과 PZT 박막이 방향성 있게 자란 것을 확인할 수 있었고 박막의 두께는 field-emission scanning electron microscope을 통하여 측정할 수 있었다. 또한 우리는 atomic force microscopy을 이용하여 박막의 표면 거칠기를 구하였고 국소적인 범위의 전기적 특성은 piezoelectric force microscopy 모드를 이용하여 측정하였다. 그 결과 PZT/LMO 구조는 나노 스토리지의 미디어로 쓰이기 위해 필요한 성질들을 갖추었음을 알 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.421-427
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• 2009

We successfully fabricated 4.7-inch organic thin film transistors array with $640{\times}480$ pixels on flexible substrate. All the processes were done by photolithography, spin coating and ink-jet printing. The OTFT-Electrophoretic (EP) pixel structure, based on a top gate OTFT, was fabricated. The mobility, ON/OFF ratio, subthreshold swing and threshold voltage of OTFT on flexible substrate are: 0.01 ^2/V-s, 1.3 V/dec, 10E5 and -3.5 V. After laminated the EP media on OTFT array, a panel of 4.7-inch $640{\times}480$ OTFT-EPD was fabricated. All of process temperature in OTFT-EPD is lower than $150^{\circ}C$. The pixel size in our panel is $150{\mu}m{\times}150{\mu}m$, and the aperture ratio is 50 %. The OTFT channel length and width is 20 um and 200um, respectively. We also used OTFT to drive EP media successfully. The operation voltages that are used on the gate bias are -30 V during the row data selection and the gate bias are 0 V during the row data hold time. The data voltages that are used on the source bias are -20 V, 0 V, and 20 V during display media operation.

• 한국전자파학회논문지
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• 제17권1호
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• pp.52-59
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• 2006

개방 단말 동축선 프로브를 사용하여 측정된 PCB 기판과 같은 박막인 유전체의 반사 계수로부터 복소 유전율을 환산하기 위해 모드 해석과 영상 전원을 써서 적분 방정식을 유도하였다. 적분 방정식에 근거한 환산 모델의 정확성은 수치 계산된 반사 계수와 측정을 통해 구한 반사 계수로부터의 복소 유전율 환산으로 확인하였다. 또한 개방 단말 동축선 프로브의 유용한 최대 주파수는 접지판의 크기에 제한 받음을 알 수 있었다.