• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.479-479
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• 2011

Flexible inverters based on complementary thin-film transistor (CTFTs) are important because they have low power consumption and other advantages over single type TFT inverters. In addition, integrated CTFTs in flexible electronic circuits on low-cost, large area and mechanically flexible substrates have potentials in various applications such as radio-frequency identification tags (RFIDs), sensors, and backplanes for flexible displays. In this work, we introduce flexible complementary inverters using pentacene and amorphous indium gallium zinc oxide (IGZO) for the p-channel and n-channel, respectively. The CTFTs were fabricated on polyimide (PI) substrate. Firstly, a thin poly-4-vinyl phenol (PVP) layer was spin coated on PI substrate to make a smooth surface with rms surface roughness of 0.3 nm, which was required to grow high quality IGZO layers. Then, Ni gate electrode was deposited on the PVP layer by e-beam evaporator. 400-nm-thick PVP and 20-nm-thick ALD Al2O3 dielectric was deposited in sequence as a double gate dielectric layer for high flexibility and low leakage current. Then, IGZO and pentacene semiconductor layers were deposited by rf sputter and thermal evaporator, respectively, using shadow masks. Finally, Al and Au source/drain electrodes of 70 nm were respectively deposited on each semiconductor layer using shadow masks by thermal evaporator. Basic electrical characteristics of individual transistors and the whole CTFTs were measured by a semiconductor parameter analyzer (HP4145B, Agilent Technologies) at room temperature in the dark. Performance of those devices then was measured under static and dynamic mechanical deformation. Effects of cyclic bending were also examined. The voltage transfer characteristics (Vout- Vin) and voltage gain (-dVout/dVin) of flexible inverter circuit were analyzed and the effects of mechanical bending will be discussed in detail.

• 비파괴검사학회지
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• 제36권4호
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• pp.288-294
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• 2016

Flexible ECT (eddy current array) probe를 사용하여 판재 및 용접부에 존재하는 notch 결함을 MS-5800E와 OmniScan MX 장비로 검출능력을 비교하고, 주파수와 lift-off를 변수로 신호의 특성을 비교하고자 하였다. 실험 결과, 500, 1000, 1500 kHz를 사용하였을 때 notch 깊이가 증가할수록 신호의 진폭이 증가하는 것으로 나타났고, lift-off 변화에 따른 신호의 진폭은 선형적으로 감소하였다. 또한 용접부 결함은 probe와 시험체의 접촉면에 밀접한 관계가 있다. Probe와 시험체의 접촉면이 양호한 경우 검출감도가 우수하고 그렇지 않은 경우에는 검출감도가 떨어지는 것을 알 수 있었다.

• 대한물리의학회지
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• 제8권4호
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• pp.533-538
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• 2013

PURPOSE: This study was performed to investigate the effect of Low-dye Taping on muscle activity during single-leg standing in subjects with flexible flatfoot. METHODS: Thirteen able-body volunteers who had flexible flatfoot were recruited for this study. Subjects were measured navicular drop test to evaluate pronation of foot and muscle activity during single-leg standing before and after taping. The muscle activity was recorded using surface EMG from the tibialis anterior and the peroneus longus during single-leg standing on stable and unstable surface. RESULTS: The results show that the navicular drop height and the tibialis anterior muscle activity were significantly decreased after Low-dye taping. CONCLUSION: The results suggest that Low-dye taping could be useful in managing overuse of the tibialis anterior by reducing their level of activation during single-leg standing.

• 센서학회지
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• 제26권3호
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• pp.173-178
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• 2017

In this paper, we newly developed an omnidirectional receiver for visible light communication (VLC). The omnidirectional receiver was composed of a flexible solar cell attached on a cylindrical surface with its axis in vertical direction. The solar cell surface was symmetrical and showed an almost uniform receiving pattern in a horizontal plane. The maximum difference in a receiving pattern was within 7% of its peak value in a horizontal plane. This configuration is very easy to fabricate and useful in constructing wireless sensor networks in which one receiver needs to detect multiple LED signals in different directions.

• 제어로봇시스템학회논문지
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• 제14권11호
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• pp.1103-1109
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• 2008

Since the flexible joint robots with motor dynamics are represented by the fifth-order nonlinear sγstem, it is difficult and complex to design the controller for electrically driven flexible-joint (EDFJ) robots. In this paper, we propose a simple adaptive control method to solve this problem. It is assumed that the model uncertainties of the robots dynamics, joint flexibility, and motor dynamics are unknown. For the simple control design, the dynamic surface design method is applied, and all uncertainties in the robot and motor dynamics are compensated by using the adaptive function approximation technique. It is proved that all signals in the controlled closed-loop system are uniformly ultimately bounded. Simulation results for three-link EDFJ manipulators are provided to validate the effectiveness of the proposed control system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.97.6-97
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• 2002

In this paper, we present an arrayed flexible tactile sensor, which can detect contact normal forces as well as positions. The tactile sensor is developed using Polyvinylidene Fluoride (PVDF) that is known as piezoelectric polymer, and the surface electrode is fabricated using silk-screening technique with silver. We develop a charge amplifier in order to amplify the small signal from the sensor, and a fast signal processing unit by using a DSP chip. The developed tactile sensor is physically flexible and it can be deformed three-dimensionally to any shape so that it can be placed on anywhere on the curved surface. In the future, the developed sensor is applied to a dexterous robotic hand...$\textbullet$ Tactile sensing, PVDF, Robot hand

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.489-492
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• 2003

In this paper, we experimented on the deterioration process of power supply cords and analyzed the heating temperature of each part of those cords. We also analyzed the surface states, metallurgical structures surface structures and compositions of the wire melted by over-current. In the results of the analyses, the covering began to be deteriorated from the inside. The heating temperature of extension cord was higher than that of plug body. The dendrite structures appeared at the melted wire. By the SEM and EDS analyses, the dendrite structure showed the growth of copper oxide. We found out the characteristics of PVC insulated flexible cords by over-current from the above experiments and analyses. These results may be useful data in the analyses of deterioration causes of power supply cords.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.314-319
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• 2000

The working surface of a flexible grinding disk was characterized by means of an image processing, in which a picture of a disk surface was taken by the CCD camera and analyzed with the personal computer. As process conditions, depth of cut was changed to be 2 and 4 mm. From the captured image circles marked on the disk was regenerated using the edges detected with scale space filtering. In order to correlate the level of deformation to the distortion of the circles, intervals between each circle have been analyzed. Notable correlation has been observed between the intervals and the process conditions.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.125-132
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• 2007

Inherent dynamic interaction between flexible disk and workpiece creates partially non-flat surface profile. A flat zone was defined using minimum depth of engagement. Several key parameters were defined to explain the characteristics of the zone. Process conditions including disk rotation speed, initial depth of cut and feed speed were varied to produce product profile database. Correlation between key factors was examined to find the characteristic dependencies. Trends of key parameters were displayed and explained. Higher flat zone ratio was observed for lower depth of cut and higher disk rotation speed. Ratio of minimum depth of cut against target depth of cut increased for higher feed speed and disk rotation speed but was insensitive to the depth of cut variation. The process transition was visualized by continuously displaying instantaneous orientation of the deflected disk and the location of key parameters were clearly marked for comparison.

• Applied Science and Convergence Technology
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• 제23권2호
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• pp.90-96
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• 2014

Flexible $ZrO_2$ films as dielectric materials for high-energy-density capacitors were deposited on polyethylene terephthalate (PET) substrates by RF magnetron sputtering. The growth behavior, microstructure and electrical properties of the flexible $ZrO_2$ films were dependent on the sputtering pressure and gas ratio. Although $ZrO_2$ films were deposited at room temperature, all films showed a tetragonal crystalline structure regardless of the sputtering variables. The surface of the film became a surface with large white particles upon an increase in the $O_2/Ar$ gas ratio. The RMS roughness and crystallite size of the $ZrO_2$ films increased with an increase in the sputtering pressure. The electrical properties of the $ZrO_2$ films were affected by the microstructure and roughness. The $ZrO_2$ films exhibited a dielectric constant of 21~38 at 1 kHz and a leakage current density of $10^{-6}{\sim}10^{-5}A/cm^2$ at 300 kV/cm.