• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.1 s.6
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• pp.57-62
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• 2005

In this paper, we propose a channel estimation method by impulse signal train in OFDM. In order to estimate the channel response, 4 impulse signals are generated and transmitted during one OFDM (Orthogonal Frequency Division Multiplexing) symbol. The intervals between the impulse signals are all equal in time domain. At the receiver, the impulse response signals are summed and averaged. And then, the averaged impulse response signal is zero padded and fast Fourier transformed to obtain the channel estimation. The BER performance of the proposed method is compared with those of conventional estimation method using the long training sequence in fast fading environments. The simulation results show that the proposed method improves by 3 dB in terms of Eb/No, compared with the conventional method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3429-3434
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• 2014

In the TFT-LCD(Thin Film Transistor-Liquid Crystal Display) panel manufacturing industry, SAMSUNG, a late entry, can catch up to leading first mover, SHARP. The changes the note, monitor, TV, and mobile markets in the TFT-LCD industry were studied using a system analysis method. In addition, the fast response time technology in SAMSUNG TFT-LCD technology was developed using the TRIZ method. For example, a new liquid crystal mixture of a wide view angle and fast response time were developed by doping a new high birefringence liquid crystal material in a base mixture using the contradiction method and su-field method of TRIZ. The response time of a new liquid crystal mixture was improved to approximately 60%(16.2ms with base LC mixture, 9.8ms with a new LC mixture).

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.794-798
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• 2016

A polymer-stabilized vertical alignment (PS-VA) mode with fishbone-shaped pixel electrode structure is mainly used in large-sized liquid crystal displays (LCDs) owing to its advantages such as wide viewing angle, good transmittance and fast response time. One drawback of this mode is a main bone electrode, which crosses in the center of a pixel. It causes the transmittance to decrease badly because LCs cannot be reoriented in this region, and thus, it is particularly unfavorable in an ultra-high-definition LCD. Here, we propose an innovative structure with the main bone electrode relocated to the edge area in a pixel, and investigate how this reverse directed fishbone-shaped pixel electrode structure affects electro-optic characteristics. The proposed structure shows enhanced electro-optic performance, such as the higher transmittance and the faster response time than the conventional VA mode with fishbone-shaped pixel electrode structure.

• PNF and Movement
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• v.20 no.1
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• pp.135-145
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• 2022

Purpose: The purpose of this study was to investigate the association between cognitive and motor inhibition by comparing muscle activity and ground reaction force during unplanned gait termination according to reaction time measured through the stop-signal task. Methods: Sixteen young adults performed a stop-signal task and an unplanned gait termination separately. The subjects were divided into fast and slow groups based on their stop-signal reaction time (SSRT), as measured by the stop-signal task. Electromyography (EMG) and ground reaction force (GRF) were compared between the groups during unplanned gait termination. The data for gait termination were divided into three phases (Phase 1 to 3). The Mann-Whitney U test was used to compare spatiotemporal gait parameters and EMG and GRF data between groups. Results: The slow group had significantly higher activity of the tibialis anterior in Phase 2 and Phase 3 than the fast group (p <0.05). In Phase 1, the fast group had significantly shorter time to peak amplitude (TPA) of the soleus than the slow group (p <0.05). In Phase 2, the TPA of the tibialis anterior was significantly lower in the fast group than the slow group (p <0.05). In Phase 3, there was no significant difference in the GRF between the two groups (p >0.05). There were no significant difference between the two groups in the spatiotemporal gait parameters (p >0.05). Conclusion: Compared to the slow group, the fast group with cognitive inhibition suppressed muscle activity for unplanned gait termination. The association between SSRT and unplanned gait termination shows that a participant's ability to suppress an incipient finger response is relevant to their ability to construct a corrective gait pattern in a choice-demanding environment.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.2
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• pp.144-155
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• 1992

A design of a highly stable current-controlled power supply combining the phase-controlled rectifier (PCR), passive filter and active filter is investigated. A digital phase-looked voltage control (PLVC) with a capability of compensating the thyristor firing angles under unvalanced power source is proposed` otherwise the PCR output voltage has low-order subharmonics whose suppression requires a bulky passive filter. The digital PLVC has a fast dynamic characteristics as an inner control loop of the PCR. To suppress further the output ripple, an active filter using a transformer is introduced and its design is described through the frequency domain analysis. An optimal integral, proportional and measurable variable feedback (IPM) controller is designed using the time-weighted performance index based on the time domain analysis. The design method based on the time-weighted performance index gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives good dynamic and static performances.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.261-273
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• 2016

Reconfigurable finite impulse response (FIR) filters whose filter coefficients and filter order change dynamically during run-time play an important role in the software defined radio (SDR) systems, multi-channel filters, and digital up/down converters. However, there are not many reports on such reconfigurable designs which can support dynamic variation of filter order and filter coefficients. The purpose of this paper is to provide an architectural solution for the FIR filters to support run-time variation of the filter order and filter coefficients. First, two straightforward designs, namely, (i) single-MAC based design and (ii) full-parallel design are presented. For large variation of the filter order, two designs based on (iii) folded structure and (iv) fast FIR algorithm are presented. Finally, we propose (v) high throughput design which provides significant advantage in terms of hardware and/or time complexities over the other designs. We compare complexities of all the five structures, and provide the synthesis results for verification.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.187-190
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• 2012

This paper proposes an one-time authentication system for web applications by making use of the quick-response code, which is widely used nowadays. The process is not time-consuming. It does not require any browser extensions or specific hardware to complete a task. The system uses QR code which is basically a two-dimensional black and white image encoding a piece of digital information. When a user logs into a site, the web server will generate a challenge encoded to form a QR code. The user captures a picture of QR code with a mobile camera which results in decoding the QR code. The challenge shall be sent back to the server; the web server then logs the PC browser in. The authentication using Challenge-Response is easy to understand and the process is fast. The system proposes the improvement of usability and security of online authentication.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.35-42
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• 1999

This paper concentrates on the position control of a pneumatic cylinder under parameter variation. A closed-loop control is proposed to design the different controllers(P, PI, PID, PD controller) in order to choose the best con-troller based on the fast and accurate control of the system. It is shown that the control algorithm, is robust and effective in attaining the fast and accurate position control of system under time-dependent parameter variation. Experimental results showed that PD controller law is effective to obtain the fast response and to increase that sta-blity of the system The method is a useful control algorithm which always automatically adjusts the position con-trol in accordance with the error using carrier wave of triangle type regardless of changes on the operating condi-tion and physical differences between components.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.143-157
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• 1994

This paper is concerned with the position control of electrohydraulic servo system under parameter variation. An adaptive sliding mode control which uses the direct parameter estimation scheme, is proposed to design a robust controller for fast and accurate control of the system. It is shown that the adaptive sliding mode control algorithm is robust and effective in attaining fast and accurate position control of system under time-dependent parameter variation. It is also shown experimentally that chattering phenomena in a sliding mode control can significantly be reduced by using boundary layer technique, and that new approach in sliding mode control introducing a term proportional to the distance between the current state and the sliding surface in the control law is effective to obtain fast response and to increase stability of the system. Computer simulation on the dynamic performance of the control system is also presented.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.33-40
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• 2004

According as client/server is generalized by development of computer performance and information communication technology, Servers uses local cache for extensibility and early response time, and reduction of limited bandwidth. Consistency of cached data need between server and client this time and much technique are proposed according to this. This Paper improved update frequency cache consistency in old. Existent consistency techniques is disadvantage that response time is late because synchronous declaration or abort step increases because delaying write intention declaration. Techniques that is proposed in this paper did to perform referring update time about object that page request or when complete update operation happens to solve these problem. Therefore, have advantage that response is fast because could run write intention declaration or update by sel_mode electively asynchronously when update operation consists and abort step decreases and clearer selection.