• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.2002-2007
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• 1999

In this paper, the n-channel poly-Si thin-film transistors (poly-Si TFT's) formed by solid phase crystallization (SPC) on glass were investigated by measuring the electrical properties of poly-Si films, such as I-V characteristics, mobility, leakage current, threshold voltage, and subthreshold slope. It is done to decide to be applied on TFT-LCD with large-size and high density. In n-channel poly-Si TFT with 2, 10, 25$\mu\textrm{m}$ of channel length, the field effect mobilities are 111, 126 and 125 $\textrm{cm}^2$/V-s and leakage currents are 0.6, 0.1, and 0.02 pA/$\mu\textrm{m}$, respectively. Low threshold voltage and subthreshold slope, and good ON-OFF ratio are shown, as well. Thus, the poly-Si TFT’s used by SPC are expected to be applied on TFT-LCD with large-size and high density, which can integrate display panel and peripheral circuit on a large glass substrate.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.254-254
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• 2011

현재 AMLCD(Active Matrix Liquid Crystal Display)는 노트북, 컴퓨터, TV등 여러 영상매체에 있어 가장 많이 활용되고 있는 디스플레이로 손꼽힌다. AMLCD에 구동소자로 사용되는 a-Si:H TFT는 낮은 제조비용과 축적된 기술을 바탕으로 가장 많이 쓰이고 있다. 특히 a-Si이 가지는 소형화나 대형화의 편의성은 모바일 기기, projection TV, 광고용 패널 등 적용분야가 점점 넓어지고 있는 추세이다. 하지만 a-Si라는 물질 자체가 가지는 낮은 이동도는 더 많은 application을 위해 해결되어야 할 과제이다. 낮은 이동도는 a-Si 실리콘 원자간 결합의 불규칙성 및 무질서와 dangling bond에 의한 localize state(deep trap, band tail)의 존재 때문에 발생하며 결과적으로 TFT 소자의 특성의 저하를 가져온다. 앞선 연구에서는 carrier이동도의 개선을 위해서 첫 번째로 insulator층과 active층 사이의 계면 상태를 향상시키기 위해 insulator로 쓰이는 a-SiN층 표면에 0~18 sccm의 유량으로 phosphorus를 주입하였다. AFM분석을 해본 결과 phosphorus를 주입함으로써 계면의 roughness가 줄어드는 것을 확인 할 수 있었다. 이러한 계면의 roughness 감소는 표면 산란(surface scattering)및 전자 포획(trap)의 영향을 줄임으로써 이동도의 향상을 가져왔다. 두 번째로 active층으로 쓰이는 a-Si:H 층의 표면에 phosphorus를 0?9sccm의 유량으로 doping하였다. 이로 인해 channel이 형성되는 active 영역에 직접적으로 불순물을 doping됨으로써 전도도를 증가되어 이동도를 향상시켰다. 하지만 지나친 doping은 불순물 산란(impurity scattering)의 증가로 인해 이동도를 저하시키는 결과를 보여 주었다. 본 연구에서는 TFT의 이동도 향상을 위해 두 가지의 technology를 함께 적용시켜 a-SiN/a-Si:H 계면 각각에 phosphorus를 주입 및 doping을 하였다. 모든 박막은 PECVD로 제작하였으며 각 박막의 두께는 a-SiN/a-SiN(phosphorus)/a-Si:H(doped)/a-Si:H/n+ a-Si($2350{\AA}/150{\AA}/150{\AA}/1850{\AA}/150{\AA}$)으로 고정하고 유량을 변화시키면서 특성을 관찰하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.232-237
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• 2019

It has recently been combined with advanced technologies such as AR and VR, and its application range is expanding to various forms of smart signage. However, until now, digital signage service that reaches us is installed in many floating populations such as bus stops, elevators, and banks and is used in the form of providing news, weather, and advertisements. In addition, large companies, government offices, and outdoor advertising companies occupy the market. The use of such services in small and medium-sized businesses and small retail stores is costly and expensive to manage. Also, it is difficult to generalize the market because services and solutions are being deployed in the market in the form of top-down. Therefore, in this paper, we proposed a digital signage system for transmitting a remote video advertisement that uses a show window in front of the store as a beam project screen for small retail stores, and can remotely set and manage and update it in OSGi service platform.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.301-305
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• 2008

An organic light-emitting diode(OLED) has advantages of low power driving, self light-emitting, wide viewing angle, excellent high resolution, full color, high reproduction, fast response speed, simple manufacturing process, or the like. However, there are still a number of challenges to get over in order to put it to practical use as a high performance display. First of all, the most important thing is to improve the efficiency of the OLED element in order to commercialize it. To this end, its efficiency can be improved by lowering the driving voltage through the improvement of structure of the OLED element and the application of new organic substance. Therefore, in this study, we have manufactured a red OLED element by applying fluorescent dyes to the emitting layer of the element having the structure of ITO/TPD/Znq2+DCJTB/Znq2/Al and the structure of ITO/CuPc/NPB/Alq3+DCJTB/Alq3/Al, in order to light-emitting various colors or improve the brightness and the efficiency, and then we have evaluated its electrical and optical characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.356-359
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• 2017

According to the plan of operation of the Ministry of Education, IWB (Interactive White Board) was distributed to one or two classrooms per school. Therefore, instead of the overhead projector (OHP) and the screen, the visual presenter and the IWB replaced the role. However, the development speed of the imaging device and the display device could not keep up, and the utilization was often lowered. In this study, we study to obtain a high resolution image using the camera of smartphone. It uses WiGig(Wireless Gigabit) technology to transmit the acquired high-resolution images to IWB or large-screen TV without delay in wireless communication. In addition, while the smartphone camera is equipped with a lens of a wide field of view(FOV), the microscope lens can be used to magnify and magnify a specific portion of a smartphone 400 times. As s result of this study it will be used as active material for real-time 400 times magnification in education and research field.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1719-1727
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• 2015

In this paper we have studied about the interconnection technology between tablet device and interactive white board(IWB) system. For this study we have implemented the board writing software for both tablet device and interactive white board system which has contents management, page turning and basic writing functions. Then we defined the data format to communicate the control information and board writing information between two devices, and implemented the communication module for the real-time bidirectional communication by using the Socket programming. The page turning or writing information on tablet device were transferred to the IWB system in real-time and vice versa. From the result of performance test based on the error rate, latency time and communication coverage we derived that our implementation software has good performance between tablet device and IWB system. Also from the result of field test we proved that our solution is well suitable to use in real education environment.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.451-451
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• 2010

최근들어 80인치 이상의 대경 고화질 display 및 휴대용 projection display 제작이 가능한 LCoS (Liquid Crystal on Silicon) display에 대한 관심이 높아지고 있다. LCoS projection display는 높은 개구율, 빠른 응답속도, 고화질, 대형 디스플레이 임에도 불구하고 낮은 제조단가 등의 여러 가지 장점을 가지고 있다. LCoS projection display의 핵심 기술로는 높은 투과도와 낮은 반사율을 갖는 유리기판, 무기 배향막 증착 기술, Si back plane과의 접합기술 등이 있다. 이 중 LCoS projection display 제작을 위한 첫 단계인 유리기판은 가시광선 영역에서 96% 이상의 높은 투과도와 3% 미만의 반사도를 요구하는 기술을 필요로 한다. 본 연구에서는 indium이 doping된 tin oxide (ITO)를 투명 전도성막으로 사용하고, $SiO_2/MgF_2$ 이중 박막을 반사방지막으로 채택하여 고투과도 및 저반사율을 갖는 유리기판 제조에 응용하였다. 먼저 15nm 두께의 ITO 박막을 DC sputtering을 이용하여 8-inch 크기의 corning1737 유리기판 상에 증착한 후, 그 반대편에 e-beam evaporation 장비를 사용하여 120nm 두께의 반사 방지막을 증착하였다. 또한 유리기판 상에 증착된 투명 전도성막의 표면개질을 위하여 Ar plasma를 이용하여 treatment를 수행하였다. 이 때 sputtering 조건은 DC power, Ar 유량 및 압력을 조절함으로서 높은 투과도를 갖는 최적의 조건을 구현하였고, e-beam evaporation을 이용한 반사방지막 증착 조건은 $SiO_2$와 $MgF_2$의 계면에서 빛의 반사를 최소화할 수 있는 최적의 조건을 구현하였다. 제작된 유리기판은 가시광선 영역에서 97% 이상의 투과도를 보였으며, 최대 2.8%의 반사율을 보여, LCoS display 제작에 적합함을 확인할 수 있었다. 또한 Ar plasma 처리 후 ITO 박막의 면저항 값은 $100\;{\omega}/{\Box}$, 표면 거칠기는 rms 값 기준 0.095nm, 접촉각 $20.8^{\circ}$의 특성을 보여, 타 index matched transparent conducting oxide가 coating된 유리기판에 비해 우수한 특성을 보였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.702-708
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• 2020

Recently, as LED display systems have become larger, research on effective power control methods for the systems has been in progress. This paper proposes a power control method to minimize power loss due to the difference in LED characteristics for each channel of a backlight unit (BLU) system. The proposed LED driver IC has a power optimization function and detects the minimum headroom voltage for constant current operation of all channels and linearly controls the DC-DC converter output. Thus, it minimizes power consumption due to unnecessary additional voltage. In addition, it does not require a voltage sensing comparator or a voltage generation circuit for each channel. This has a great advantage in reducing the chip size and for stabilization when implementing an integrated circuit. In order to verify the proposed function, an IC was designed using Cadence and Synopsys' design tools, and it was fabricated with a Magnachip 0.35um 5V/40V CMOS process. The experiments confirmed that the proposed power control method controls the minimum required voltage of the BLU system.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.1
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• pp.11-15
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• 2016

The organic light emitting diodes (OLEDs) have been studied as large flexible displays, light source and hard wares of internet of things. However, OLEDs show some drawbacks in terms of external environments due to the low work function of the metals and the reactive organic materials. In particular, the operation functions of the OLEDs tend to deteriorate rapidly by exposing the oxygen and moisture. So as to prevent it, domestic and overseas studies underway in various method such as ALD, PVD, CVD. But it has complex process and high cost. Therefore In order to protect devices from the external environments, it is important to develop the passivation thin films of low-cost and simple process which can prevent the devices from the penetration of the oxygen and moistures. In this study, to improve the reliability, passivation thin films were coated onto the green OLEDs by spin coating method and investigated the changes of the optical properties of the prepared devices at various doping concentrations of sodium alginate (SA). The passivation solutions were synthesized by using polyvinyl alcohol (PVA) host material with a dopant of SA which were added with the amounts of 10, 20 and 40 wt% into the PVA. As a result, the best barrier properties of the OLEDs were obtained for the samples with 40 wt% SA. Finally, the passivation films can be optimized by using the mixture solution of PVA and SA materials.

• Journal of Broadcast Engineering
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• v.22 no.4
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• pp.484-495
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• 2017

The development of display devices and the increase of network transmission bandwidth bring demands for over 2K high resolution video such as panorama video, 4K ultra-high definition commercial broadcasting, and ultra-wide viewing video. To compress these image sequences with significant amount of data, High Efficiency Video Coding (HEVC) standard with the highest coding efficiency is a promising solution. HEVC, the latest video coding standard, provides high encoding efficiency using various advanced encoding tools, but it also requires significant amounts of computation complexity compared to previous coding standards. In particular, the complexity of HEVC decoding process is a imposing challenges on real-time playback of ultra-high resolution video. To accelerate the HEVC decoding process for ultra high resolution video, this paper introduces a data-level parallel video decoding method using slice and/or tile supported by HEVC. Moreover, deblocking filter process is further parallelized. The proposed method distributes independent decoding operations of each tile and/or each slice to multiple threads as well as deblocking filter operations. The experimental results show that the proposed method facilitates executions up to 2.0 times faster than the HEVC reference software for 4K videos.