• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.4
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• pp.69-78
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• 2010

The irreversible 9/7 JPEG2000, which is one of sub-band coding techniques, has a problem of severe picture quality distortion at the edge and the background caused by the quantization error below 0.15bpp. In this paper, to solve such problems we propose a VQ(Visual Quantizer) based on L-pdf(Laplace probability density function) statistical characteristics of high frequency sub-bands. The proposed VQ is designed by visual parameter for improving the subjective quality and weighting parameter for increasing the compression ratio. A proposed method, based on 9/7 JPEG2000 scheme, gives the high subjective quality to reconstructed images below 0.15bpp and provides minimum MSE(Mean-Squared Error) regardless of the compression ratio.

• The Journal of the Acoustical Society of Korea
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• v.23 no.4
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• pp.333-339
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• 2004

This Paper proposes the vector quantizer-pyramid vector quantizer(VQ-PVQ) structure. Also both predictive structure and safety-net concept are combined into the VQ-PVQ to quantize the IPC parameter of wideband speech codec. The Performance is compared to the LPC vector quantizer used in the AMR-WB(ITU-T G.722.2). demonstrating reduction in both spectral distortion and encoding memory.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.76-81
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• 2004

Problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. However, their compactness, power/weight ratio, ease of maintenance and inherent safety are factors that could be potentially exploited in sophisticated dexterous manipulator designs. These advantages have led to the development of novel actuators such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle Manipulators. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external inertia load in the pneumatic artificial muscle manipulator. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is newly proposed. This estimates the external inertia load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external inertia loads.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.289-292
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• 2002

This paper provides a frame-layer method for controlling bit rate of compressed video data in real time. Our approach is easy to operate and can store encoded video data in real time without deteriorating the quality of an image. To provide ameliorated and consistent visual quality, a new concept named SOP (Set Of Pictures) and a new quantization parameter variation control algorithm based on a second-order rate-distortion model 〔2〕 are introduced. The total bit-budget is allocated efficiently to cope with unpredictable recording time by using the proposed algorithm and it is distributed to each frame. In the end, we show improved and consistent video quality with experimental results obtained from C-model of a MPEG-4 (simple-profile) encoder.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.723-726
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• 2001

일반적으로 블록기반의 동영상 압축방식은 블록킹효과를 필연적으로 수반한다. 특히 저비트율의 동영상에서는 블록킹 효과가 다른 어떤 영상의 왜곡보다 많이 발생한다. 본 논문에서는 이러한 블록킹효과를 효율적으로 인간 시각체계에 적합하게 실시간으로 제거하는 후처리 알고리즘을 제안한다. 우선 복원된 영상에서 인간의 시각체계와 동영상의 특성에 따라 3가지의 모드로 분리하여 QP(quantization Parameter)에 따라 임계치를 변화함으로써 각 모드의 필터링 범위를 가변시켰다. 이후에 각 모드에 알맞은 일차원 및 적응형 필터링을 적용한다. 적용된 모드별 필터링은 과도한 블러링 현상을 방지하고 영상내의 실제 에지성분읓 보호하면서 효과적으로 블록킹효과를 제거한다. 본 논문에서 제안하는 알고리즘을 실험 영상에 적용하였을 경우에 주관적 화질 및 객관적 화질인 PSNR로 0.5dB 정도 향상되었다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.157-160
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• 2000

In the generally a voice conversion has used VQ(Vector Quantization) for partitioning the spectral feature and has performed by adding an appropriate offset vector to the source speaker's spectral vector. But there is not represented the target speaker's various characteristics because of discrete characteristics of transformed parameter. In this paper, these problems are solved by using the LMR(Linear Multivariate Regression) instead of the mapping codebook which is determined to the relationship of source and target speaker vocal tract characteristics. Also we propose the method for solved the discontinuity which is caused by applying to time aligned parameters using Dynamic Time Warping the time or pitch-scale modified speech. In our proposed algorithm for overcoming the transitional discontinuities, first of all, we don't change time or pitch scale and by using the LMR change a speaker's vocal tract characteristics in speech with non-modified time or pitch. Compared to existed methods based on VQ and LMR, we have much better voice quality in the result of the proposed algorithm.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1388-1400
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• 2004

Problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. However, their compactness, power/weight ratio, ease of maintenance and inherent safety are factors that could be potentially exploited in sophisticated dexterous manipulator designs. These advantages have led to the development of novel actuators such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle Manipulators. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external inertia load in the pneumatic artificial muscle manipulator. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is newly proposed. This estimates the external inertia load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external inertia loads.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.49-56
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• 1998

Super precision working technique and machine tool have been continually developed thanks to advanced electronic field. To obtain good result. it is necessary to investigate surface in grinding with $mu extrm{m}$ level. There were quite many researches to satisfy these demands by using non-contact methods through the computer vision. In this study, the texture of working surface was analyzed. co-occurrence matrices was obtained from the surface roughness. Texture parameter was obtained using position operator composed of $ heta$, d according to variation of angle direction and distance. As a result, it was found that surface texture was more affected by direction($\theta$) than distance(d).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.97-100
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• 2014

최근 초고화질 해상도(UHD) 영상 서비스에 따른 기존의 비디오 압축 기술인 H.264/AVC 대비 두 배 이상의 압축 성능을 가지는 HEVC(High-Efficiency Video Codec)의 표준화가 완료되었다. 그러나 높은 압축 효과를 얻기 위하여 복잡한 연산이 필요한 기법들이 많이 도입되어 HEVC의 부호화 복잡도는 H.264/AVC보다 크게 증가되었다. 예로써 HEVC의 화면내 예측 부호화는 예측 방향를 최대 35개까지 확장함으로써 기존 H.264/AVC에 비해서 향상된 부호화 효율을 갖지만 화면내 부호화의 복잡도는 크게 증가되어 복잡도 감소 기법이 필요하다. 본 논문은 화면내 예측 부호화에 사용되는 예측 방향 35가지를 비디오 해상도와 양자화 파라미터 크기를 고려하여 4가지 모드로 나누고 비디오 해상도의 따른 PU(Prediction Unit)의 크기의 점유율에 따라 예측 방향 개수를 변경함으로써 계산 복잡도를 감소시키는 기법을 제안한다. 실험 결과를 통해 제안된 기법을 적용함으로써 대략 2%의 BD-rate 증가로 부호화 시간을 4% 감소시킬 수 있었다.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.99-106
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• 2005

In recent years, vision sensors are widely used to mobile robot for navigation or exploration. The analog signal transmission of visual data being used in this area, however, has some disadvantages including noise weakness in view of the data storage. A large amount of data also makes it difficult to use this method for a mobile robot. In this paper, a digital data compressing technology based on MPEG4 which substitutes for analog technology is proposed to overcome the disadvantages by using DWT(Discreate Wavelet Transform) instead of DCT(Discreate Cosine Transform). The TI Company's DSP chip, TMS320C6711, is used for the image encoder, and the performance of the proposed method is evaluated by PSNR(Peake Signal to Noise Rates), QP(Quantization Parameter) and bitrate.