• 한국통신학회논문지
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• 제24권12B호
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• pp.2415-2423
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• 1999

We propose a new optical method which conceals the data of authorized persons by encryption before they are stored or compared in the pattern recognition system for security systems. This proposed security system is made up of two subsystems : a proposed optical encryption system and a pattern recognition system based on the JTC which has been shown to perform well. In this system, each image of authorized persons as a reference image is stored in memory units through the proposed encryption system. And if a fingerprint image is placed in the input plane of this security system for access to a restricted area, the image is encoded by the encryption system then compared with the encrypted reference image. Therefore because the captured input image and the reference data are encrypted, it is difficult to decrypt the image if one does not know the encryption key bit stream. The basic idea is that the input image is encrypted by performing optical XOR operations with the key bit stream that is generated by digital encryption algorithms. The optical XOR operations between the key bit stream and the input image are performed by the polarization encoding method using the polarization characteristics of LCDs. The results of XOR operations which are detected by a CCD camera should be used as an input to the JTC for comparison with a data base. We have verified the idea proposed here with computer simulations and the simulation results were also shown.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.518-521
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• 2004

We have investigated about compensation film to reduce the light leakage at an oblique angle in-plane switching mode. It is well known that uncompensated in-plane switching (US) and fringe field switching (FFS) liquid crystal displays (LCDs) have much better viewing angle than other modes owing to the in-plane rotation of the LC director. However, to accomplish optimal viewing angle characteristics in these devices, they must be compensated by one or more films. So, in this paper, we have studied how to reduce the light leakage with viewing angle using discotic film in dark state.

• Membrane and Water Treatment
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• 제14권1호
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• pp.47-54
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• 2023

In this study, high concentrations of cadmium-containing wastewater were treated by electrodialysis (ED) with a channel stack. The limiting current density (LCD), cadmium removal efficiency, and current efficiency were investigated under each experimental condition according to the Reynolds number (Re), membrane area, and pH. With the increase in the film area to 111, 333, 555, and 777 cm² at Re (109.1), LCDs decreased to 408.11, 44.45, 35.32, and 13.64 A/m², respectively. The highest cadmium removal efficiency (99.6%) and current efficiency were obtained for the membrane area of 111 and 777 cm², respectively. Under changing Re in the pH range of 1 to 4, Re and LCD were proportional under the same pH condition, and pH and LCD tended to be inversely proportional under the same Re condition. Cadmium removal rate was the best at the pH range 3 - 4. It has been found that ED with channeled stacks can be successfully applied to treat wastewater containing high concentrations of cadmium.

• 한국분말재료학회지
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• 제30권5호
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• pp.436-441
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• 2023

Molybdenum-tungsten (Mo-W) alloy sputtering targets are widely utilized in fields like electronics, nanotechnology, sensors, and as gate electrodes for TFT-LCDs, owing to their superior properties such as high-temperature stability, low thermal expansion coefficient, electrical conductivity, and corrosion resistance. To achieve optimal performance in application, these targets' purity, relative density, and grain size of these targets must becarefully controlled. We utilized nanopowders, prepared via the Pechini method, to obtain uniform and fine powders, then carried out spark plasma sintering (SPS) to densify these powders. Our studies revealed that the sintered compacts made from these nanopowders exhibited outstanding features, such as a high relative density of more than 99%, consistent grain size of 3.43 ㎛, and shape, absence of preferred orientation.

• IEIE Transactions on Smart Processing and Computing
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• 제5권3호
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• pp.193-198
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• 2016

Lane change is an important issue in microscopic traffic flow simulations and active safety. Overtaking and changing lanes are dangerous driving maneuvers. This approach presents a lane-changing system based on speed and a minimum gap between vehicles in a vehicular ad hoc network (VANET). This paper proposes a solution to ensure the safety of drivers while changing lanes on highways. Efficient routing protocols could play a crucial role in VANET applications, safeguarding both drivers and passengers, and thus, maintaining a safe on-road environment. This paper focuses on the development of an intelligent transportation system that provides timely, reliable information to drivers and the concerned authorities. A test bed is created for the techniques used in the proposed system, where analysis takes place in an on-board embedded system designed for vehicle navigation. The designed system was tested on a four-lane road in Neemrana, India. Successful simulations were conducted with real-time network parameters to maximize quality of service and performance using Simulation of Urban Mobility and Network Simulator 2 (NS-2). The system implementation, together with the findings, is presented in this paper. Illustrating the approach are results from simulation using NS-2.

• 한국광학회지
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• 제25권6호
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• pp.301-310
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• 2014

현재 Fringe-field switching(FFS) 액정 모드는 고화질 및 고정세 액정 디스플레이에 주로 적용되고 있다. 본 총설에서는 FFS모드의 어떠한 동작원리가 기존에 다른 액정모드 보다 왜 우수한 전기광학 특성을 갖는지에 대한 상세 한 설명과 더불어 FFS모드의 역사적 발전 현황, 기술의 현 주 이슈 및 향후 발전방향을 기술한다.

• 한국정보전자통신기술학회논문지
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• 제2권1호
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• pp.3-9
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• 2009

AMOLED 디스플레이는 LCD에 비해 넓은 시야각, 빠른 응답 속도, 박막화의 용이성 등의 많은 장점들을 갖고 있으나 불균일한 TFT의 전기적 특성과 전원선의 전압 강하에 의한 휘도 불균일, 잔상 현상 및 수명 등과 같은 많은 문제점들이 있다. 이 중에서 본 논문에서는 구동 TFT 소자의 hysteresis 현상에 의해 발생하는 가역적 잔상 현상을 개선하고자 한다. TFT의 hysteresis 특성을 개선하기 위해 게이트 산화막 증착 전에 표면 처리 조건을 변경하였다. 게이트 산화막 증착 전에 실시한 자외선 및 수소 플라즈마 표면 처리는 게이트 산화막과 다결정 실리콘 박막 사이의 계면 trap 밀도를 $3.11{\times}10^{11}cm^{-2}$로 감소시켰고, hysteresis 레벨을 0.23 V로 줄였으며 출력 전류 변화율을 3.65 %로 감소시켰다. 자외선 및 수소 플라즈마 처리를 행함으로써 AMOLED 디스플레이의 가역적 잔상을 많이 개선할 수 있을 것으로 기대된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.180-180
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• 2015

Solution processed Resistive random access memory (ReRAM)은 간단한 공정 과정, 고집적도, 저렴한 가격, 대면적화 플라즈마 데미지 최소화 등의 장점으로 차세대 비휘발성 메모리로 써 많은 관심을 받고 있으며, 주로 high-k 물질인 HfOx, TiOx, ZnO 가 이용 된다. IGZO와 ZTO와 같은 산화물 반도체는 높은 이동도, 대면적화, 넓은 밴드갭으로 인하여 투명한 장점으로 LCDs (Liquid crystal displays)에 이용 가능하며, 최근에는 IGZO와 ZTO에서 Resistive Switching (RS) 특성을 확인한 논문이 보고되면서 IGZO와 ZTO를 ReRAM의 switching medium와 TFT의 active material로써 동시에 활용하는 것에 많은 관심을 받고 있다. 이와 같은 산화물 반도체는 flat panel display 회로에 TFT와 ReRAM의 active layer로써 집적가능 하며 systems-on-panels (SOP)에 적용 가능하다. 하지만 IGZO 보다는 ZTO가 In과 Ga을 포함하지 않기 때문에 저렴하다. 그러므로 IGZO를 대신하는 물질로 ZTO가 각광 받고 있다. 본 실험에서는 ZTO film에 Al을 doping하여 메모리 특성을 평가하였다. 실험 방법으로는 p-type Si에 습식산화를 통하여 SiO2를 300 nm 성장시킨 기판을 사용하였다. 그리고 Electron beam evaporator를 이용하여 Ti를 10 nm, Pt를 100 nm 증착 한다. 용액은 Zn와 Tin의 비율을 1:1로 고정한 후 Al의 비율을 0, 0.1, 0.2의 비율로 용액을 각각 제작하였다. 이 용액을 이용하여 Pt 위에 spin coating방법을 이용하여 1000 rpm 10초, 6000 rpm 30초의 조건으로 AZTO (Al-ZnO-Tin-Oxide) 박막을 증착한 뒤, solvent 및 불순물 제거를 위하여 $250^{\circ}C$의 온도로 30분 동안 열처리를 진행하였다. 이후 Electron beam evaporator를 이용하여 top electrode인 Ti를 100 nm 증착하였다. 제작된 메모리의 전기적 특성은 HP 4156B semiconductor parameter analyzer를 이용하여 측정하였다. 측정 결과, AZTO (0:1:1, 0.1:1:1, 0.2:1:1)를 이용하여 제작한 ReRAM에서 RS특성을 얻었으며 104 s이상의 신뢰성 있는 data retention특성을 확인하였다. 그리고 Al의 비율이 증가할수록 on/off ratio가 증가하고 endurance 특성이 향상되는 것을 확인하였다. 결론적으로 Al을 doping함으로써 ZTO film의 메모리 특성을 향상 시켰으며 AZTO film을 메모리와 트랜지스터의 active layer로써 활용 가능할 것으로 기대된다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.843-846
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• 2004

For the fast growing Liquid Crystal Display (LCD) TV market, it is essential to make the LCD panels to show moving images without any visual difficulties such as blurring or tailing. Owing to reduction of the cell gap and the improved Liquid Crystal (LC) mixtures with low viscosity, it is possible that our S-IPS TFT-LCDs feature a response time (R/T) as fast as 1-frame time (16ms) for a white-black operation and less than a 16rns in all gray levels without Over Driving Circuit (ODC) technology. Currently, mass production of the large size IPS panels with high speed has been successfully achieved. In order to achieve faster response time, new LC mixtures have been developed, optimizing the physical properties of rotational viscosity (${\gamma}$1) and elastic constants (Kii). Also, the LC mixtures with high elastic constant allow us to increase the cell gap. In this paper, realization of fast switching time in IPS mode with optimized '${\gamma}$1/Kii' parameter in the LC mixtures forms the core of this paper.

• 대한기계학회논문집A
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• 제30권7호
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• pp.741-749
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• 2006

For last couple of decades, uses of TFI-LCDs have been expanded to many FPD(Flat Panel Display) applications including mobile displays, desktop monitors and TVs. Furthermore, there has been growing demand for increasingly larger LCD TVs. In order to meet this demand as well as to improve productivity, LCD manufactures have continued to install larger-generation display fabrication facilities which are capable of producing more panels and larger displays per mother glass(substrate). As the size of mother glass becomes larger, a robot required to handle the glass becomes bigger accordingly, and its end effectors(arms) are extended to match the glass size. With this configuration, a considerable static deflection occurs at the end of the robot arms. In order to stack maximum number of mother glasses on a given footprint, the static deflection should be compensated. This paper presents a novel static deflection compensation algorithm. This algorithm requires neither measurement instrument nor additional vertical axis on the robot. It is realized by robot controller software. The forward and inverse kinematics considering compensation always guarantees a unique solution, so the proposed algorithm can be applied to an arbitrary robot position. The algorithm reduced static deflection by 40% in stationary robot state experiment. It also improved vertical path accuracy up to 60% when the arm was running at its maximum speed. This algorithm has been commercialized and successfully applied to a seventh-generation LCD glass-handling robot.