• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.2-290.2
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• 2016

Recently, organic thin-film transistors have been widely researched for organic light-emitting diode panels, memory devices, logic circuits for flexible display because of its virtue of mechanical flexibility, low fabrication cost, low process temperature, and large area production. In order to achieve high performance OTFTs, increase in accumulation carrier mobility is a critical factor. Post-fabrication thermal annealing process has been known as one of the methods to achieve this by improving the crystal quality of organic semiconductor materials In this paper, we researched the properties of pentacene films with X-Ray Diffraction (XRD) and Atomic Force Microscope (AFM) analyses as different annealing temperature in N2 ambient. Electrical characterization of the pentacene based thin film transistor was also conducted by transfer length method (TLM) with different annealing temperature in Al- and Ti-pentacene junctions to confirm the Fermi level pinning phenomenon. For Al- and Ti-pentacene junctions, is was found that as the surface quality of the pentacene films changed as annealing temperature increased, the hole-barrier height (h-BH) that were controlled by Fermi level pinning were effectively reduced.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.944-949
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• 2017

Recently, the demand of maglev systems in the manufacturing industry for LCD and OLED display panels, which are required to be very clean and possess vacuum systems, has been increasing due to their characteristics such as being non-contact, noise free and eco-friendly. However, it is still a challenge to simultaneously control both the propulsion and levitation for their interactive effect difficult to be exactly measured. In this paper, we proposed a new tuning method for controlling the magnetic levitation force robustly against the levitation disturbance caused by a propulsion system, based on LQ servo optimal control. The disturbance torque of the LSM propulsion system is calculated through FEM analysis in such a way that the LQ servo controller is determined in order to minimize the effect of the disturbance. The robust performance of the proposed LQ servo control method for the in-track type magnetic levitation systems is demonstrated via simulations and experiments.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.881-884
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• 2004

The robust and large-area applicable metal shadow masks with a high aspect ratio more than 20 are fabricated by a combination of micro-electro-discharge machining (${\mu}$-EDM) and electro chemical etching (ECE). After defining S/D contacts using a 100 ${\mu}m$ thick stainless steel shadow mask, the top-contact pentacene TFTs with channel length of 5 ${\mu}m$ showed routinely the results of mobility of 0.498 ${\pm}$ 0.05 $cm^2$/Vsec, current on/off ratio of 1.6 ${times}$ $10^5$, and threshold voltage of 0 V. The straightly defined atomic force microscopy (AFM) images of channel area demonstrated that shadow effects caused by the S/D electrode deposition were negligible. The fabricated pentacene TFTs have an average channel length of 5 ${\pm}$ 0.25 ${\mu}m$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.203-204
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• 2009

The Indium Zinc Tin Oxide (IZTO) thin films for flexible display electrode were deposited on poly carbonate (PC) and polyethersulfone(PES) and glass substrates at room temperature by facing targets sputtering (FTS). Two different kinds of targets were installed on FTS system. One is ITO ($In_2O_3$ 90 wt.%, $SnO_2$ 10 wt.%), the other is IZO ($In_2O_3$ 90 wt.%, ZnO 10 wt.%). As-deposited IZTO thin films were investigated by a UV/VIS spectrometer, an X-ray diffractometer (XRD), an atomic force microscope (AFM) and a Hall Effect measurement system. As a result, we could prepare the IZTO thin films with the resistivity of under $10^{-4}\;[{\Omega}{\cdot}cm]$ and IZTO thin films deposited on glass substrate showed an average transmittance over 80% in visible range (400~800 nm) in all IZTO thin films except in IZTO thin film deposited at $O_2$ gas flow rate of 0.1[sccm].

• 대한기계학회논문집A
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• 제31권12호
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• pp.1173-1179
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• 2007

In recent years, research to machine large-surface micro-features has become important because of the light guide panel of a large-scale liquid crystal display and the bipolar plate of a high-capacity proton exchange membrane fuel cell. In this study, in order to realize the systematic design technology and performance improvements of an ultra-precision machine for machining the large-surface micro-features, a structural characteristic analysis was performed using its virtual prototype. The prototype consisted of gantry-type frame, hydrostatic feed mechanisms, linear motors, brushless DC servo motor, counterbalance mechanism, and so on. The loop stiffness was estimated from the relative displacement between the tool post and C-axis table, which was caused by a cutting force. Especially, the causes of structural stiffness deterioration were identified through the structural deformation analysis of sub-models.

• 한국재료학회지
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• 제10권5호
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• pp.350-353
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• 2000

강유전성 액정 분자 배향을 위해 열방성 고분자 액정물질을 배향막으로 사용하고 그표면 morphology를 AFM(Atomic Forced Microscope)으로 관찰한 결과 잘 배향된 sample cell에서도 microgroove 구조가 나타나지 않았음을 관찰하였다. 잘 배향된 sample cell 23:1의 contrast ratio를 보이면서 memory 효과를 나타내었다. 또한 20V의 AC field로 안정화시키자 전형적인 stripe-shaped 무늬가 나타났다.

• 대한기계학회논문집A
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• 제27권1호
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• pp.18-25
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• 2003

A haptic hand controller (HHC) operated by the user’s hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. In this paper, a 3-DOF hand controller is first presented, in which all the actuators are mounted on the fixed base by combining a 5-bar linkage and a gimbal mechanism. The 6-DOF HHC is then designed by connecting these two 3-DOF devices through a handle which consists of a screw and nut. Analysis using performance index is carried out to determine the dimensions of the device. The HHC control system consists of the high-level controller for kinematic and static analysis and the low-level controller for position sensing and motor control. The HHC used as a user interface to control the mobile robot in the virtual environment is given as a simple application.

• 한국진공학회지
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• 제6권4호
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• pp.321-325
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• 1997

LCD용 칼라 필터를 제작하는 방법으로 감광성 고분자(photosensitive polymer)에 광 리소그라피(photolithography)기술이 많이 이용되어지고 있다. 이로 인해 감광성 고분자 표 면의 물리적, 화학적 성질이 변하게 되는데, 이는 후속 공정인 플라즈마 식각이나 ITO 전극 의 증착 등에도 많은 영향을 주므로, 각 공정에 따른 이들 고분자의 표면 연구는 매우 중요 하다. 본 논문에서는 blue 칼라 필터의 고분자 표면에 대한 연구를 SIMS와 XPS를 이용하 여 수행하였으며, 표면의 거칠기 변화를 AFM을 통해 관찰하였다. SIMS와 XPS결과로부터 초기 공정인 blue 칼라 필터를 스핀 코팅하고 pre bake한 상태에서는 주로 칼라 필터의 주 성분인 단량체와 결합제의 고분자 물질이 표면에 드러나 있다가, 노광 과정을 거치고 post bake한 시료에서는 색깔을 내는 안료 성분이 표면에 드러남을 확인하였고, AFM을 통해서 는 post bake후에 표면에 더 거칠어 짐을 관찰하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.575-575
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• 2013

Indium Zinc Oxide (IZO)는 가시광 영역(380~780 nm)에서 높은 투과율과 적외선영역에서 높은 반사율을 보이는 투명산화막으로서 Flexible display 적용으로 주목 받는 재료이다. 특히 비 화학적 양론비(non-stoichiometric)로 성장된 박막은 N형 반도체 특성을 갖기 때문에 광전자 소자, 액정표시소자와 태양전지의 투명전극 재료로 이용되고 있으며, 향 후에도 수요는 계속 증가될 전망이다. 일반적으로 IZO 박막은 높은 열처리 온도에 의한 기판재료의 선택이 한정적인 단점이 있다. 따라서 최근에는 정밀하게 제어된 에너지를 가진 전자를 표면에 조사(E-beam irradiation)하여 박막의 물성을 개선하고 기판재료의 선택성을 넓히는 연구가 활발히 진행되고 있다 [1]. 본 연구에서는 RF Magnetron Sputtering 법을 이용하여 Glass 위에 IZO를 증착하였다. 스퍼터링타겟은 고순도 IZO 타겟을 이용하여 100 nm의 두께를 가지는 박막을 증착하였다. 증착된 IZO 박막에 E-beam Source ((주)인포비온)를 이용하여 E-beam irradiation energy 조건에 변화를 주어 박막의 물성 변화를 관찰하였다. IZO 박막의 두께를 측정하기 위해 SEM (Cross section)을 이용하였다. E-beam irradiation energy에 따른 가시광 영역(380~780 nm)에서의 광투 과도는 UV-Vis spectrometer를 사용하여 측정하였고, 전기적인 특성은 Hall measurement system 을 이용하여 측정하였다. 또한 박막의 결정성과 거칠기의 변화는 XRD (X-ray Diffraction)와 원자 간력현미경(Atomic Force Microscope; AFM)을 이용하여 측정하였다. Rf magnetron Sputtering 법을 이용하여 증착한 IZO 박막에 Post E-beam irradiation이 전기전도 및 광 투과특성과 결정성과 표면 조도를 향상시키는데 크게 기여함을 확인할 수 있었다.

• 로봇학회논문지
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• 제15권4호
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• pp.323-329
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• 2020

This paper presents a control algorithm for a wearable walking aid robot for subjects with paraplegia after stroke. After a stroke, a slow, asymmetrical and unstable gait pattern is observed in a number of patients. In many cases, one leg can move in a relatively normal pattern, while the other leg is dysfunctional due to paralysis. We have adopted the so-called assist-as-needed control that encourages the patient to walk as much as possible while the robot assists as necessary to create the gait motion of the paralyzed leg. A virtual wall was implemented for the assist-as-needed control. A position based admittance controller was applied in the swing phase to follow human intentions for both the normal and paralyzed legs. A position controller was applied in the stance phase for both legs. A power controller was applied to obtain stable performance in that the output power of the system was delimited during the sample interval. In order to verify the proposed control algorithm, we performed a simulation with 1-DOF leg models. The preliminary results have shown that the control algorithm can follow human intentions during the swing phase by providing as much assistance as needed. In addition, the virtual wall effectively guided the paralyzed leg with stable force display.