• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.5 s.311
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• pp.72-78
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• 2006

In this paper, we present a video shot retrieval algorithm in H.264/AVC compression domain. Unlike previous standards such as MPEG-2 and 4, H.264/AVC supports a variable block size for motion compensation. Therefore, existing video retrieval algorithms exploiting the motion vectors in MPEG-2 and 4 domains are not appropriate for H.264/AVC. So, we devise a method to project motion vectors with larger than $4{\times}4$ block sizes into those for the smallest $4{\times}4$ blocks. It also uses correlations among features for the measure of similarity. Experimental results with standard videos of 10558 frames and commercial videos of 48161 frames show that the proposed method yields ANMRR less than 0.2.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.1-8
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• 2007

The purpose of this study was to investigate the difference in the stride-to-stride variability between two treadmill conditions; traditional treadmill and special treadmill whose speed can be adjusted automatically by subject's walking speed. Eight male subjects (25.1 years, 172.7 cm, 66.6 kg) were participated in treadmill walking experiment. First, preferred walking speed (PWS) of each subject was determined. Second, each subject performed walking experiment with fixed PWS condition and with free PWS condition for 10 minutes. 3D motion capture system (Motion analysis Corp., USA) with 6 cameras was used to collect motion data with sampling frequency of 120Hz. Temporal and spatial variables for stride-to-stride variability were calculated. Coefficient of variance (CV) which quantifies the amount of variability and Detrended Fluctuation Analysis (DFA) which explains the structure (self-similarity) of the variability were used for analysis. Results showed that the amount of variability during free PWS condition was greater than that of fixed PWS condition. DFA results showed that there was a statistical difference between two treadmill conditions for the variables of step length, stance time, and double support time. From these results, it is possible that traditional treadmill study might give incorrect conclusion about gait variability study. Further study is necessary to clarify these matters by considering the number of subjects, experimental time, and gait variables for the study of stride-to-stride variability.

• Advances in concrete construction
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• v.14 no.2
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• pp.103-113
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• 2022

On the basis of fabrication, the utilization of nano material in numerous industrial and technological system, obtained the utmost significance in current decade. Therefore, the current investigation presents a theoretical disposition regarding the flow of electric conducting Williamson nanoliquid over a stretchable surface in the presence of the motile microorganism. The impact of thermal radiation and magnetic parameter are incorporated in the energy equation. The concentration field is modified by adding the influence of chemical reaction. Moreover, the splendid features of nanofluid are displayed by utilizing the thermophoresis and Brownian motion aspects. Compatible similarity transformation is imposed on the equations governing the problem to derive the dimensionless ordinary differential equations. The Homotopy analysis method has been implemented to find the analytic solution of the obtained differential equations. The implications of specific parameters on profiles of velocity, temperature, concentration and motile microorganism density are investigated graphically. Moreover, coefficient of skin friction, Nusselt number, Sherwood number and density of motile number are clarified in tabular forms. It is revealed that thermal radiation, thermophoresis and Brownian motion parameters are very effective for improvement of heat transfer. The reported investigation can be used in improving the heat transfer appliances and systems of solar energy.

• Journal of Broadcast Engineering
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• v.7 no.1
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• pp.45-54
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• 2002

This paper proposes a video compression algorithm using characteristics of wavelet coefficients. The proposed algorithm can provide lowed bit rate and faster running time while guaranteeing the reconstructed image qualify by the human virtual system. In this approach, each video sequence is decomposed into a pyramid structure of subimages with various resolution to use multiresolution capability of discrete wavelet transform. Then similarities between two neighboring frames are obtained from a low-frequency subband which Includes an important information of an image and motion informations are extracted from the similarity criteria. Four legion selection filters are designed according to the similarity criteria and compression processes are carried out by encoding the coefficients In preservation legions and replacement regions of high-frequency subbands. Region selection filters classify the high-frequency subbands Into preservation regions and replacement regions based on the similarity criteria and the coefficients In replacement regions are replaced by that of a reference frame or reduced to zero according to block-based similarities between a reference frame and successive frames. Encoding is carried out by quantizing and arithmetic encoding the wavelet coefficients in preservation regions and replacement regions separately. A reference frame is updated at the bottom point If the curve of similarity rates looks like concave pattern. Simulation results show that the proposed algorithm provides high compression ratio with proper Image quality. It also outperforms the previous Milton's algorithm in an Image quality, compression ratio and running time, leading to compression ratio less than 0.2bpp. PSNR of 32 dB and running tome of 10ms for a standard video image of size 352${\times}$240 pixels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.459-462
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• 2000

The analysis of distribution line faults is essential to the proper protection of power system. A high impedance fault(HIF) dose not make enough current to cause conventional protective device operating. so it is well hon that undesirable operating conditions and certain types of faults on electric distribution feeders cannot be detected by using conventional protection system. In this paper, we prove that the nature of the high impedance faults is indeed a deterministic chaos, not a random motion Algorithms for estimating Lyapunov spectrum and the largest Lyapunov exponent are applied to various fault currents detections in order to evaluate the orbital instability peculiar to deterministic chaos dynamically, and fractal dimensions of fault currents which represent geometrical self-similarity are calculated. Wavelet transform analysis is applied the time-scale information to fault signal. Time-scale representation of high impedance faults can detect easily and localize correctly the fault waveform.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.663-667
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• 2009

본 논문에서는 인접블록간의 움직임 유사도를 이용하여 불필요한 후보블록을 보다 빠르게 제거하는 PDE기반의 고속 블록매칭 알고리즘을 제안한다. 제안한 방법은 기존의 방법보다 불필요한 계수를 효율적으로 제거하기 위하여 인접 블록간의 영상의 유사성에 기초하여 인접한 네개의 매크로블록 가운데 최대 복잡도를 가지는 서브블록의 누적된 비율(cumulative distribution function-CDF)을 사용하고 서브블록별 복잡도가 집중되지 않도록 하기위하여 normalized 기반 매칭스캔 방법을 사용하여 효율적으로 계산량을 줄였다. 제안한 알고리즘은 화질의 저하 없이 기존의 PDE 알고리즘에 비해 60% 이상의 계산량을 줄였으며, MPEG-2 및 MPEG-4 AVC를 이용하는 비디오 압축 응용분야에 유용하게 사용될 수 있을 것이다.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.386-392
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• 2007

최근 들어 손 제스처를 인간-기계 인터페이스에 활용하는 연구가 많아지고 있다. 그 중에서 수화 인식은 청각장애인과 일반인 사이의 원활한 의사 소통을 하게 해 주는 인터페이스로서 중요성이 날로 더해가고 있다. 하지만 기존의 수화 인식 연구는 사용자 개개인의 수화 동작의 차이를 고려하지 않고 다수 사용자를 위한 모델을 사용하기 때문에 사용자에 따라 인식률이 낮아지게 된다. 이러한 점을 보완하기 위해 본 논문에서는 개개인의 수화 동작 특성을 반영하여 시스템이 사용자에게 적응해 가는 과정을 다루고자 한다. 특히 점진적인 사용자 적응에 있어서 가장 문제가 되는 것은 어떻게 비관측된 상태(unobserved state)의 파라미터를 수정할 것인가 하는 것이다. 이를 위해서 본 논문에서는 동작 유사도와 적응 추이에 의한 추정을 통해 비관측된 상태의 모델 파라미터를 수정한다. 실제 청각 장애인들로부터 획득한 데이터베이스를 사용하여 제안한 방법이 기존 방법에 비해 더욱 빠르게 사용자의 특성을 시스템에 반영하고 인식률을 향상시킨다는 것을 실험을 통해 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.379-388
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• 2000

Previous studies on high impedance faults assumed that the erratic behavior of fault current would be random. In this paper, we prove that the nature of the high impedance faults is indeed a deterministic chaos, not a random motion. Algorithms for estimating Lyapunov spectrum and the largest Lyapunov exponent are applied to various fault currents in order to evaluate the orbital instability peculiar to deterministic chaos dynamically, and fractal dimensions of fault currents, which represent geometrical self-similarity are calculated. In addition, qualitative analysis such as phase planes, Poincare maps obtained from fault currents indicate that the irregular behavior is described by strange attractor.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.909-910
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• 2008

For evaluating the performance of some codecs, many researchers have study and develop new objective video quality assessments. However, it's not sufficient for evaluating the temporal feature of video data yet, which is a distinguishable and representative characteristic when compared with other multimedia. This paper propose the method to apply the weight to SSIM (Structural SIMilarity) according to the cognitive psychological feature. And, we presented that the performance of objective video quality assessment applied the weight to SSIM by using the proposed method is superior to one of original SSIM.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1053-1059
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• 2001

Results from direct numerical simulation and LDV measurements are analyzed to investigate the influence of structured surface on turbulence in the outer layer. To provide a well-defined surface roughness, sinusoidal wavy surface was used. Even though flows over smooth and wavy surface show very different process for maintaining turbulence in the vicinity of the wall, there are some evidences that the turbulence in the outer layer has a universal characteristics and it may be possible to give a speculative interpretation that similarity of turbulent structures arises because Reynolds stress producing motion is similar regardless of different turbulence generation mechanisms embedded in both cases.