• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.709-715
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• 2010

This paper represents a map building and localization system for mobile robot. Map building and navigation is a complex problem because map integrity cannot be sustained by odometry alone due to errors introduced by wheel slippage, distortion and simple linealized odometry equation. For accurate localization, we propose sensor fusion system using encoder sensor and indoor GPS module as relative sensor and absolute sensor, respectively. To build a map, we developed a sensor based navigation algorithm and grid based map building algorithm based on Embedded Linux O.S. A wall following decision engine like an expert system was proposed for map building navigation. We proved this system's validity through field test.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.250-253
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• 2009

This paper presents NR (No Reference) Quality assessment method for IPTV or mobile IPTV. Because No Reference quality assessment method does not access the original signal so it is suitable for the real-time streaming service. Our proposed method use decoding parameters, such as quantization parameter, motion vector, and packet loss as a major network parameter. To evaluate performance of the proposed algorithm, we carried out subjective test of video quality with the ITU-T P.910 ACR (Absolute Category Rating) method and obtained the mean opinion score (MOS) value for QVGA 180 video sequence coded by H.264/AVC encoder. Experimental results show the proposed quality metric has a high correlation (84%) to subjective quality.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.71-72
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• 2006

In this study, automatic assembly and evaluation system fer phone camera module is conceptually designed. The designed core(Auto focus & UV curing, Image Test) equipments adopts a clustering mechanism and compactible structure using index table for minimum tact time. Using a ball screw actuator and absolute encoder in each axis, we can verifies the repeatability and position accuracy of system within ${\pm}3{\mu}m$. In result of simulation test, the proposed system is expected up to 30% in productivity than manual operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.887-888
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• 2006

Switched Reluctance Motor(SRM) is rotated by reluctance force generated between rotor pole and stator pole. So SRM must be switched by exciting current according to rotor position. but SRM takes the advantages of high speed driving and very simple structure. The single phase SRM can not be start by itself and torque ripple is generated more than multi-phase SRM. But mechanical structure and driver is simpler than multi-phase SRM. The single phase SRM driver is composed with the absolute encoder and DSP to control exciting section and current, and is supplied by constant voltage. So The paper is intend to measure the speed charactrer of double silent pole type SRM by using the unipolar driving curcuit.

• 전력전자학회논문지
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• 제23권1호
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• pp.72-75
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• 2018

An initial rotor position estimation method is proposed in this study for an interior permanent-magnet synchronous motor without a resolver or an absolute encoder. This method uses least squares approximation to estimate the initial rotor position. The magnetic polarity is identified by injection of short pulses. The proposed estimation process is robust because it does not require complex signal processing that depends on the performance of a digital filter. In addition, it can be applied to various servo systems because it does not require additional hardware. Experimental results validate the effectiveness of the proposed method using a standard industrial servomotor with interior-permanent magnets.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집
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• pp.53-56
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• 2004

This paper describes the method of position error reduction in Linear Pulse Motor (LPM). Though the micro step exiting method is applied, the vibration and position error caused by trust distortion from mechanism still remains. This paper presents the method for reduction of position error on moving the mover at whole cycle, by compensating a scale factor through real-time control of the PWM pulse width corresponding to exiting current command and absolute position error from linear encoder.

• 전자공학회논문지S
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• 제35S권5호
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• pp.94-102
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• 1998

In this paper, we proposed a dynamic selection scheme of advnaced prediction mode(DAPM), which reduces computational cost and improves coding efficiency. We can select the mode between default prediction mode (DPM) and advanced prediction mode (APM) according to motion componenets in a frame dynamically. For this purpose, we defined error distribution of motion estimation (EDME) as sum of absolute difference(SAD) for each searching points. This distribution region is divided to four subregions. We calculate minimum values in each subregions and then, we determine whether block motion estimation is performed or not depending on the results. As a result, we reduced computational complexity to 30% without degradation of image quality compared to fixed APM(FAPM) by selecting DPM for linear movement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.955-957
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• 2003

In this paper deal with Initial Pole Position Estimation for Interior Permanent Magnet Motor. Generally, Brushless motor is considered Initial Pole Position with absolute encoder or resolver, etc. In the motor, the flux from the magnets is large enough to saturate the stator iron, results in different inductance values along the pole position. Based upon the relationship between magnitude of inductance and the resultant magnetic filed, initial pole position is estimated at standstill without position sensors, especially, this paper provide the direction of the magnetization. Finally, analysis results are presented to confirm ability of initial pole position estimation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.385-405
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• 2019

High Efficiency Video Coding (HEVC) enables significantly improved compression performance relative to existing standards. However, the advance also requires high computational complexity. To accelerate the intra prediction mode decision, a minimum risk Bayesian classification framework is introduced. The classifier selects a small number of candidate modes to be evaluated by a rate-distortion optimization process using the sum of absolute Hadamard transformed difference (SATD). Moreover, the proposed method provides a loss factor that is a good trade-off model between computational complexity and coding efficiency. Experimental results show that the proposed method achieves a 31.54% average reduction in the encoding run time with a negligible coding loss of 0.93% BD-rate relative to HEVC test model 16.6 for the Intra_Main common test condition.

• 대한전자공학회논문지SP
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• 제40권5호
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• pp.388-396
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• 2003

본 논문에서 정수단위 화소(integer pixel unit)로 움직임 예측(motion estimation)을 수행하는 빠른 움직임 예측(fast motion estimation) 알고리즘을 제안한다. 제안하는 방법은, sum norm을 사용하여 가장 좋은 움직임 벡터를 찾아내는 연속 제거 기법(SEA : Successive Elimination Algorithm)을 기반으로 16×16블록에서는 전체 영역에 대해 검색을 하고 16×8, 8×16, 8×8블록에서는 16×16블록의 움직임 벡터로부터 그 주위 8개의 위치에서 가장 좋은 벡터를 구하고, 8×4, 4×8, 4×4블록은 8×8블록의 움직임 벡터로부터 그 주위 8개의 위치에서 벡터를 검색하여 그 중에서 가장 좋은 움직임 벡터를 찾아내는 것이다. 이러한 움직임 검색(motion search) 방법을 가변 크기 블록(16×16, 16×8, 8×16, 8×8, 8×4, 4×8, 4×4)으로 움직임 예측을 하는 H.264 부호기(encoder)에 적용하였다. 제안하는 검색 알고리즘을 계산 복잡도 측면에서 보면, 조기 종료가 적용 안 된 나선형으로 전체 영역을 검색(Spiral full search without early termination)하는 방법보다 23.8배가 빨라졌고, 4×4 블록들의 계층적 SAD(Sum of Absolute Difference)를 이용하는 빠른 움직임 예측 방식보다 4.6배의 속도증가를 보인다. 반면에 신호 대 잡음 비(PSNR : Peak Signal to Noise Ratio)는 0.1dB에서 0.4dB정도 떨어짐을 보인다.