• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.352.1-352.1
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• 2014

Indium Tin Oxide (ITO) films are the most extensively studied and commonly used as ones of TCO films. The ITO films having a high electric conductivity and high transparency are easily fabricated on glass substrate at a substrate temperature over $250^{\circ}C$. However, glass substrates are somewhat heavy and brittle, whereas plastic substrates are lightweight, unbreakable, and so on. For these reasons, it has been recently suggested to use plastic substrates for flexible display application instead of glass. Many reaearchers have tried to produce high quality thin films at rood temperatures by using several methods. Therefore, amorphous ITO films excluding thermal process exhibit a decrease in electrical conductivity and optical transparency with time and a very poor chemical stability. However the amorphous Indium Gallium Zinc Oxide (IGZO) offers several advantages. For typical instance, unlike either crystalline or amorphous ITO, same and higher than a-IGZO resistivity is found when no reactive oxygen is added to the sputter chamber, this greatly simplifies the deposition. We reported on the characteristics of a-IGZO thin films were fabricated by RF-magnetron sputtering method on the PEN substrate at room temperature using 3inch sputtering targets different rate of Zn. The homogeneous and stable targets were prepared by calcine and sintering process. Furthermore, two types of IGZO TFT design, a- IGZO source/drain material in TFT and the other a- ITO source/drain material, have been fabricated for comparison with each other. The experimental results reveal that the a- IGZO source/drain electrode in IGZO TFT is shown to be superior TFT performances, compared with a- ITO source/drain electrode in IGZO TFT.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1563-1568
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• 2012

Printed electronics is a technology used for forming electronic circuits or devices, and it is used in the manufacture of many products such as RFID tags, solar cells, and flexible display panels with a much lower cost than in the case of semiconductor process technology. Web-guide-type printing such as roll-to-roll printing is a method used to produce printed electronic devices in a large volume. To commercialize such products, highly precise alignment between printed layers is required. In this study, a highly precise alignment system is proposed, and some experimental results are compared with those obtained using a laser surface vibrometer to illustrate the reliability of the proposed system. The robustness of the proposed system to web deformation is also considered experimentally.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.117-117
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• 2000

높은 광학적 투과성과 전기전도성을 갖는 ITO film은 solar cell같은 optoelectronic device나 휴대용 소형 TV, flat panel display 등의 투명전극으로 그 응용 분야가 광범위하여 많은 연구가 수행되어져 왔다. 기판으로서 유리를 사용할 때 생기는 활용범위 제한을 극복하고자 최근 유기물 위에 증착이 가능한 저온 증착방법에 대한 연구가 활발히 이루어지고 있다. 그 가운데 이온빔과 같은 energetic한 beam을 이용한 박막의 제조는 기판을 플라즈마 발생지역으로부터 분리시켜 이온빔의 flux 및 에너지, 입사각 등의 자유로운 조절을 통해 상온에서도 우수한 성질의 박막형성 가능성이 제시되어 지고 있다. ITO박막을 형성하는 방법 중 스프레이법이나 CVD법과 같은 화학적 증착방법은 증착시 350-50$0^{\circ}C$의 고온이 필요하고 현재 가장 많이 응용되어 지고 있는 sputter법은 15$0^{\circ}C$정도의 가열이 필요하므로 앞으로 응용가능성이 매우 커서 많은 연구가 진행중인 플라스틱과 아크릴 같은 flexible 한 기판위 증착에 적용이 불가능하다. 본 실험에서는 IBAD(Ion Beam Assisted Deposition)법을 이용하여 저온 ITO film을 유리와 유기막위에 증착하는 연구를 수행하였다. 유기막위에 증착된 ITO는 보다 가볍고 충격에 강하고 유리에 못지 않은 투과성을 가지고 있으나 현재 film의 quality 향상에 대한 요구가 증대되어 지고 있는 실정이다. 따라서, 본 실험에서는 dual oxygen ion gun의 조건변화에 따른 ITO film의 특성변화를 관찰하였다. 고정된 증？율에 한 개 ion gun에 ion flux를 고정시킨 후 또 다른 ion gun에서 발생하는 oxygen radical의 영향을 조사하였으며 oxygen radical의 rf power에 따른 변화는 OES(Optical emission spectroscopy)를 사용하였다. 너무 적은 oxygen ion beam flux나 oxygen radical은 film의 전도도 및 투과도를 저하시켰고 반면 너무 과도한 flux의 증가 시는 전도도는 감소하였고 투과도는 증가하는 경향을 보였다. 기판에 도달하는 oxygen ion flux는 faraday cup을 이용하여 측정하였으며 증착된 ITO film은 XPS, UV-spectrometer, 4-point probe를 이용하여 분석하였다.

• International Journal of Highway Engineering
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• v.2 no.4 s.6
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• pp.111-122
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• 2000

PMS(Pavement Management System) has been developed and/or operated for the freeway and national highway systems in Korea. There is, however, no municipal PMS that is necessary in many cities for efficient management of their roadways. In this study, a municipal Prototype PMS is developed. The Prototype PMS is designed to be operated on PC base. It uses GIS interface for user friendliness that applies color graphics, text and distress pictures to display pavement conditions and rehabilitation information for both current and historical situations. The computer program of the prototype PMS consists of four major functions(inquiry, analysis, data management, and print). Especially, prioritization and M&R(Maintenance and Rehabilitation) alternative selection procedure is designed to be flexible so that the users can modify the decision criteria whenever it is necessary. Database items of the Prototype PMS is carefully selected for the objectives and size of municipal PMS. Reference point method is basically used for the location referencing in the Database. The unit section consists of each loom segment of the road for effective management.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.388-388
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• 2011

Graphene, with its unique physical and structural properties, has recently become a proving ground for various physical phenomena, and is a promising candidate for a variety of electronic device and flexible display applications. The physical properties of graphene depend directly on the thickness. These properties lead to the possibility of its application in high-performance transparent conducting films (TCFs). Compared to indium tin oxide (ITO) electrodes, which have a typical sheet resistance of ~60 ${\Omega}/sq$ and ~85% transmittance in the visible range, the chemical vapor deposition (CVD) synthesized graphene electrodes have a higher transmittance in the visible to IR region and are more robust under bending. Nevertheless, the lowest sheet resistance of the currently available CVD graphene electrodes is higher than that of ITO. Here, we report an ingenious strategy, irradiation of MeV electron beam (e-beam) at room temperature under ambient condition,for obtaining size-homogeneous gold nanoparticle decorated on graphene. The nano-particlization promoted by MeV e-beam irradiation was investigated by transmission electron microscopy, electron energy loss spectroscopy elemental mapping, and energy dispersive X-ray spectroscopy. These results clearly revealed that gold nanoparticle with 10~15 nm in mean size were decorated along the surface of the graphene after 1.0 MeV-e-beam irradiation. The fabrication high-performance TCF with optimized doping condition showed a sheet resistance of ~150 ${\Omega}/sq$ at 94% transmittance. A chemical transformation and charge transfer for the metal gold nanoparticle were systematically explored by X-ray photoelectron spectroscopy and Raman spectroscopy. This approach advances the numerous applications of graphene films as transparent conducting electrodes.

• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.128-132
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• 2009

Transparent conducting thin films of indium tin oxide(ITO) co-sputtered with aluminum-doped zinc oxide(AZO) were deposited on glass substrate by dual magnetron sputtering. It was found that the electrical properties and structural characteristics of the films are significantly changed according to the sputtering power of the AZO target. The IAZTO film prepared with D.C power of ITO at 100 W and R.F power of AZO at 50 W shows an electrical resistivity of $4.6{\times}10^{-4}{\Omega}{\cdot}cm$ and a sheet resistance of $30{\Omega}/{\square}$ (for 150 nm thick). Besides of the improvement of the electrical properties, compared to the ITO films deposited at the same process conditions, the IAZTO films have very smooth surface, which is due to the amorphous nature of the films. However, the electrical conductivity of the IAZTO films was found to be deteriorated along with the crystallization in case of the high temperature deposition (above $310^{\circ}C$). In this work, high quality amorphous transparent conductive oxide layers could be obtained by mixing AZO with ITO, indicating possible use of IAZTO films as the transparent electrodes in OLED and flexible display devices.

• Korean Journal of Optics and Photonics
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• v.31 no.3
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• pp.134-141
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• 2020

Optical three-dimensional (3D) measurement systems based on digital fringe projection are used in many contactless measurement applications. The system which can measure a dozen micrometers uses a liquid-crystal display (LCD) as the projection unit for generating a digital fringe pattern, because a flexible fringe pattern can be easily made by computer software. According to the gamma nonlinearity of the LCD projection unit, the digital fringe projection error on the object affects the accuracy of 3D object measurement. An improved method of LCD gamma-nonlinearity error reduction is proposed, by using the inverse function of the intensity transfer function to improve the accuracy. The improvement due to the proposed method is shown by measuring the difference in precision between a computer-generated sine wave and a camera-obtained sine wave for a standard semiconductor specimen.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.456-463
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• 2015

Nowadays, small quantity batch production, which is so-called a flexible manufacturing system, is a major trend in the modern factory automation industry. The demands for new transportation system are increased gradually, with which multiple passive carriers carrying materials and semi-products are precisely and individually controlled along a single closed rail. Thus, a new type of permanent magnet linear synchronous motor (PMLSM), which consists of state coils on a single rail and PM movers as many as carriers, is proposed in this paper. The rail can be segmented as modules with pairs of coils and a current amplifier, which makes the transportation system simple; therefore, the rail can be easily extended and repaired. A design method of the new PMLSM with a single carrier is proposed, which can be thought as a new version of PMLSM, a coil-segmented coreless PMLSM (CS-CLPMLSM). Experimental setup for it is made, and propulsion results show that with the help of a new effective coil selection and switching algorithms, the conventional current-based vector control is sufficient to fulfill the position and velocity control of the new PMLSM. The proposed PMLSM is expected to fulfill seamless servo-control of multiple carriers also in process line, such as a new generation of flat panel display manufacturing line.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.615-620
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• 2020

Oxide semiconductor, represented by a-IGZO, has been commercialized in the market as active layer of TFTs of display backplanes due to its various advantages over a-Si. a-IGZO can be deposited at room temperature by RF magnetron sputtering process; however, additional thermal annealing above 300℃ is required to obtain good semiconducting properties and stability. These temperature are too high for common flexible substrates like PET, PEN, and PI. In this work, effects of microwave annealing time on IGZO thin film and associated thin-film transistors are demonstrated. As the microwave annealing time increases, the electrical properties of a-IGZO TFT improve to a degree similar to that during thermal annealing. Optimal microwave annealed IGZO TFT exhibits mobility, SS, V_th, and V_H of 6.45 ㎠/Vs, 0.17 V/dec, 1.53 V, and 0.47 V, respectively. PBS and NBS stability tests confirm that microwave annealing can effectively improve the interface between the dielectric and the active layer.