• Electrical & Electronic Materials
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• v.10 no.1
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• pp.15-19
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• 1997

The characteristics of the response time and the viewing angle on twisted nematic (TN) liquid crystal display (LCD) and amorphous (a)-TN-LCD without rubbing were investigated. To measure the tansmission-voltage, response time, and viewing angle characteristics, we prepared three kinds of LC cells and then studied the surface liquid crystal alignment effect. It was found that the response time on A-TN-LCD was fast compared to the TN-I-CD, and the weak anchoring strength was attributed to the fast response time on a-TN-LCD. Also, we obtained the wide viewing angle characteristics on a-TN-LCD. The liquid crystal alignment of LCD device for electro-optical characteristics is discussed in the present paper.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.536-540
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• 2004

A novel nematic liquid crystal (LC) cell with splay structure exhibiting wide viewing angle, fast response time and high transmittance at the same time has been developed. With rubbed homeotropic alignment in parallel directions, the device shows bend alignment in the absence of vertical electric field. However, with applied high voltage in a pulse form, the LC shows a optically compensated splay (OCS) orientation such that the mid-director is parallel to a substrate and at both surfaces the LCs are aligned vertically in parallel direction. In the device, the birefringence of the cell becomes tunable with applying voltage, i.e., the amount of light passed through the cell can be controlled by controlling the orientation of the LC. Since the OCS cell has a self-compensation structure such that the LC has a mirror symmetry along the mid-director, the device shows a wide viewing angle with only a single domain and a fast response time.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2099-2106
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• 2003

In this paper, a novel fast response NDIR analyzer (FRNDIR), which uses an electrically pulsed semiconductor emitter and dual type PbSe detector for the PPM-level detection of carbon dioxide (CO$_2$) at a wavelength of 4.28 $\mu\textrm{m}$, is described. Modulation of conventional NDIR energy typically occurs at 1 to 20 Hz. To achieve real time high-speed measurement, the new analyzer employs a semiconductor light emitter that can be modulated by electrical chopping. Updated measurements are obtained every one millisecond. The detector has two independent lead selenide (PbSe) with IR band pass filters. Both the emitter accuracy and the detector sensitivity are increased by thermoelectric cooling of up to -20 degrees C in all semiconductor devices. Here we report the use of semiconductor devices to achieve improved performance such that these devices have potential application to CO$_2$ gas measurement and, in particular, the measurement of fast response CO$_2$ concentration at millisecond level.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1991.10a
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• pp.53-58
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• 1991

This paper presents the speed control of DC motor based on deadbeat response method. Since 송 deadbeat response systems are characterized by the discrete time control, the instabiliby of the systems caused by saturation and time lag problems is inevitable. In order to release these problems, we propose a compensator utilizing the predictive control so that the fast response can be also achieved in the saturation state. Experimental results demonstrated that outputs are able to settle final values in on sampling time for unsaturated reference inputs. For saturated reference inputs, outputs take one sampling time after getting free from the saturation state. Further we are able to settle the fast response with suppressed overshoot by appling the predictive control.

• Journal of Power Electronics
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• v.9 no.3
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• pp.507-515
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• 2009

This paper proposes an autonomous decentralized control for a parallel connected uninterruptible power supply (UPS) system based on a fast power detection method using a FPGA based hardware controller for a single phase system. Each UPS unit detects only its output voltage and current without communications signal exchange and a quasi dq transformation method is applied to detect the phase and amplitude of the output voltage and the output current for the single phase system. Fast power detection can be achieved based on a quasi dq transformation, which results in a realization of very fast transient response under rapid load change. In the proposed method, the entire control system is implemented in one FPGA chip. Complicated calculations are assigned to hardware calculation logic, and the parallel processing circuit makes it possible to realize minimized calculation time. Also, an Nios II CPU core is implemented in the same FPGA chip, and the software can be applied for non-time critical calculations. Applying this control system, an autonomous decentralized UPS system with very fast transient response is realized. Feasibility and stable operation are confirmed by means of an experimental setup with three UPSs connected in parallel. Also, rapid load change is applied and excellent performance of the system is confirmed in terms of transient response and stability.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.457-459
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• 2005

Low viscosity LCs have been developed for fast response time improvement of the TFT-LCD Monitors based on TN mode. This low viscosity characteristic s cause the pretilt angle to be changed and the uniformity to degrade. We have studied on the pretilt angle effect by the various components used for low viscosity LCs. We prepared the panels by using these various components and measured pretilt angle for this research. As a result of this research, we have found out that each low viscosity component has the different pretilt angle level and uniformity. For good display quality, it is important to keep the stable pretilt angle. The low viscosity LCs with this stable pretilt angle make it possible to prepare the high performance TFT-LCD Monitor with both fast response time characteristics and good display quality

• Proceedings of the IEEK Conference
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• 2003.07d
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• pp.1515-1518
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• 2003

This paper suggests the condensed two-stage retrieval method for fast image retrieval in the content-based image retrieval system, and proves the validity of the performance. The condensed two-stage retrieval method reduces the overall response time remarkably while it maintains relevance with the conventional exhaustive search method. It is explained by properties of the Cauchy-Schwartz inequality. In experimental result, it turns out that there is an optimal value of condensation ratio which minimizes the overall response time. We analyze the optimal condensation ratio by modeling a similarity computation time mathematically.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.911-914
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• 2004

This paper discusses on new two LCD technologies featured by the fast electro-optic response:one is polymer-stabilized FLCDs that exhibit V-shaped electro-optic (EO) switching called PSV-mode FLCDs with response time of 400 ${\mu}$ s; and the other is TN-mode LCDs that exhibit a frequency modulation response (called PM-TN LCDs)and a peculiar sensitivity to the high frequency component of driving voltage waveforms resulting in a short decay time constant of 5ms and an enhancement in the over-driving that yields short response time of 1ms between two gray levels.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.180-182
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• 1996

In this study, we have investigated the characteristics of the response time and the viewing angle on twisted nematic (TN)-liquid crystal display (LCD) and amorphous (a) TN-LCD without rubbing. To measure the transmission-voltage, response time, and viewing angle characteristics, we prepared three kinds of LC cells and then studied the surface liquid crystal alignment effect. We studied that the response time on a-TN-LCD is fast compared to the TN-LCD. We suggest that the weak anchoring strength is attributed to the fast response time on a-TN-LCD. Also, we obtained the uniform viewing angle characteristics on a-TN-LCD. From these results, we consider that the liquid crystal alignment on LCD device are very important factor for electro-optical characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.59-60
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• 2009

The conventional in-plane field driven-vertical alignment display (VA-IPS) shows fast response time but transmittance shows very low and operating voltage is very high. In this paper, we studies electro-optical properties of the novel in-plane field driven vertical alignment device which has two transistors on array part and common electrode on CF substrate with dielectric layer. The device shows fast response time and high transmittance.