• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.814-817
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• 2006

In this paper we report the influence of rubbing direction and electrode distance to the voltage dependent transmittance in in-plane switching (IPS) mode. Moreover, we applied this to a transflective IPS cell to realize a single gamma characteristics both in the transmissive part and the reflective part..

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1031-1035
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• 1993

In this paper, we suggest a new algorithm diminishing the chattering in sliding mode control by setting a dead-band along the switching line on the phase plane although nonlinear terms of an nonlinear system are regarded as disturbances and apply this algorithm to the trajectory control of SCARA robot By this algorithm, we can expect the high performance of the trajectory trajet of an industrial robot which needs a robust and simple algorithm.

• Journal of Information Display
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• 제10권4호
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• pp.175-179
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• 2009

As the physical properties of nematic liquid crystals vary with respect to temperature, the performances of liquid crystal displays (LCDs) are highly dependent on temperature. Additionally, it is well known that the electro-optic characteristics of LCDs, such as transmittance and threshold voltage, also rely on the LCD switching modes. The temperature dependence of the electro-optic characteristics of the wide-viewing-angle LCD modes, such as in-plane switching (IPS), multidomain vertical alignment by patterned electrode (PVA), and fringe-field switching (FFS), have been studied, and the results showed that the FFS mode has lower temperature dependence compared to the IPS and PVA modes. Since the liquid crystal (LC) reorients in different ways in each mode, this result is associated with the temperature dependence of LC's bend and twist elastic constants, and also with the position of the main reorientation, either in the middle or on the surface of the LC layer.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.792-795
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• 2006

In-plane-switching (IPS)-mode LCD is one of the most useful technologies for a broad range of viewing angles. To apply for IPS-LCDs, we synthesized novel homogeneous alignment materials, changing dianhydrides (BTDA and BPDA) and bridged diamines (ODA and PACM). We measured their pre-tilt angles using the crystal rotation method with positive LC and their surface properties.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.672-676
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• 2009

Polymide is widely used alignment material of recent commercial LCD panel structure. Generally, polyimide alignment material is classified soluble polyimide type and polyamic acid type with their main bond structure of solution state. specially, compared to polyamic acid alignment layer, soluble polyimide type alignment layer have excellent reliability during long term LCD driving cause of their high imidazation ratio(%), high voltage holding ratio(%) and low ion density. The other side, this type alignment materials has significant DC image stickicng side effect for using in-plane switching mode lcd structure cause of their slow DC discharging property. we applied inorganic salt to usual soluble polyimide type alignment layer and found out this technique had good DC image sticking property without any loss of reliability property in inplane switching LCD cell structure. This approach leads excellent DC image sticking property with maintaining high reliability property this approach confirmed improves an image sticking and a reliability simultaneously from the horizontality aligned LCD mode whose relatively bad image sticking property.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.280-282
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• 1994

This paper proposes sliding mode state for robust speed control of induction motor. Sliding mode state observer is robust for measurement noise, modeling-error and load disturbance. The pole of sliding mode state observer can be placed at (0,0) in Z-plane for fast response. This method is, namely, deadbeat control. Sliding mode state observer output is discontinuous on a switching hyperplance, that causes harmful effects such as current harmonics and speed oscillation. In this paper, also the reducing method of the chattering of sliding mode state observer output is proposed. The proposed system is digitally implemented with TMS320C31.

• 대한전자공학회논문지SD
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• 제39권4호
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• pp.10-18
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• 2002

본 논문에서는 IPS모드의 액정 셀에서 전압에 따른 액정 거동을 수치 해석적으로 계산하는 방법을 보고한다. 액정 거동을 해석하기 위해 복잡한 구조에 적용이 용이한 3차원 유한 요소법을 사용하여 액정 셀 내부의 전압 분포와 전계 분포를 계산하였다. 전기 에너지와 액정 분자의 탄성 에너지로 이루어지는 액정 셀 내부의 자유에너지 밀도를 고려하였으며, 에릭슨-레슬리(Ericksen-Leslie) 방정식과 라플라스(Laplace) 방정식을 해석함으로서 액정 셀의 스위칭 특성을 계산하였다. 24㎛×12㎛×4.5㎛ 사이즈의 IPS 모드 액정 셀에 대하여 1,859개의 노드와 8,640개의 사면체 요소를 생성하여 16ms까지 과도 해석하였다. 그 결과, 전극 위 부분을 제외한 영역에서 횡방향의 전계가 형성되었고, 전극 위 영역에서 전경선(disclination)이 발생하는 것을 확인하였다.

• 대한전자공학회논문지
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• 제26권4호
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• pp.27-34
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• 1989

可變 構造 시스템 理論을 適用한 適應 모델 追從 制御器를 設計 하였다. 變形된 슬라이딩 모드 條件을 滿足시키는 提案된 制御器는 狀態 軌跡의 슬라이딩 平面 到達 速度를 改善하고 슬라이딩 모드에서 채터링의 크기를 줄이도록 한다. 슬라이딩 平面 近處의 領域에서 制御入力을 바꿈으로써 채터링을 줄이고 이 結果를 컴퓨터 시뮬레이션을 통하여 立證하였다.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.260-264
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• 2015

We propose a negative liquid crystal (n-LC) cell with parallel patterned electrodes for high transmittance and fast response. The proposed cell has higher transmittance and shorter response time than a conventional fringe-field switching cell using n-LCs, because the proposed cell does not have transmittance dips and does have a thinner LC layer.

• 한국해양공학회지
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• 제11권4호
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• pp.169-179
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• 1997

This paper presents a discrete-time sliding mode control of an autonomous underwater vehicle with parameter uncertainties and long sample interval based on discrete variable structure system. Although conventional sliding mode montrol techniques are robust to system uncertainties, in the case of the system with long sample interval, the sliding control system reveals chattering phenomenon and even makes the system unstable. This paper considers the AUV which acquires position informations from a surface ship through an acoustic telemetry system with a certain discrete interval. The control system is designed on the basis of a Lyapunov function and a sufficient condition of the switching gain to make the system stable is give. Each component of the switching gain can be determined separately one another. The controller is robust to the uncertainties, and reaching condition of the control system is satisfied for any initial condition. This control law is a generalized form of the discrete sliding mode control and reduce the chattering problem considerably. Motion control of the AUV in the vertical plane shows the effectiveness of the proposed technique.