• 방송공학회논문지
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• 제17권6호
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• pp.1029-1039
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• 2012

본 논문에서는, 인터 예측시 움직임 벡터의 해상도를 나타내는 1비트 플래그를 두어 적응적으로 1/4 해상도의 움직임 벡터와 1/8 해상도의 움직임 벡터를 선택하고 부호화하는 방법을 제안한다. 현재 HEVC에서는 1/4 해상도의 움직임 벡터만을 이용하여 부호화하는데, 영상 신호의 변화가 복잡한 영역에서 1/4 해상도의 움직임 벡터만으로는 충분한 효율을 얻어내지 못한다. 따라서 본 논문에서는 PU마다 해상도 플래그를 1비트 추가하여 적응적으로 움직임 벡터의 해상도를 결정할 수 있도록 한다. 제안한 방법의 실험 결과로서, 인코더의 복잡도는 30%~33% 증가하고 디코더의 복잡도는 1%~5% 증가하였지만, 휘도신호의 압축효율은 최대 5.3% 좋아졌으며, 색차신호의 압축효율은 최대 7.9% 좋아졌다.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1391-1398
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• 2011

본 논문은 장비의 동작분석기법을 이용하여 운전자가 핸들을 돌릴 때 팔의 관절 운동에 대한 생체역학적 해석을 수행하였다. 모형 운전석에서 운전자가 핸들을 돌릴 때 모션 캡쳐(motion capture) 시스템을 이용하여 팔의 3차원 운동궤적을 구하고, 이 결과를 이용하여 팔의 근-골격계 모델에 대한 역기구학 해석과 역동역학 해석을 수행함으로써 팔 관절의 변위와 관절 토크의 크기를 계산하였다. 각 관절의 회전 운동은 동시에 복합적으로 발생하며, 관절 운동의 크기의 관점에서 팔꿈치 관절의 회내-회외, 어깨 관절의 내전-외전, 굴곡-신전, 손목 관절의 굴곡-신전 등이 주요한 운동임을 확인할 수 있었다. 모형 운전석의 운전 자세, 핸들의 각도 및 좌석에 대한 상대적 위치와 관련된 설계변수에 대한 관절운동의 민감도 해석을 통하여 운전 자세와 핸들의 위치가 조향 동작에 미치는 영향을 정량적으로 분석하였다.

• 방송공학회논문지
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• 제8권2호
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• pp.181-197
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• 2003

대역 분할 부호화(Sub-Band Coding: SBC)방식은 계층적 피라미드(hierarchical pyramid) 구조를 갖고 있어 움직임 예측 시 상위 계층에서는 전체적인 이동특성을 추정하고 하위 계층에서는 국부적인 세부 이동 특성을 추정할 수가 있어 실제 동영상 움직임 보상 성능이 매우 우수하다. 이와 같은 계층적 이동보상피라미드를 이용한 기존의 저대역(low-band) 이동보상 피라미드 방식에는 다음 두 가지 문제점들로 인해 매우 심각한 화질 저하가 발생한다. 첫째는 저대역 이동보상 피라미드의 각 계층에서 양자화기가 포함된 부호화기를 사용할 경우 하위 계층의 재생 영상일수록 상위 계층에서 누적된 양자화 오차(quantization error)들을 그대로 포함하기 때문에 연속된 영상에서의 정확한 이동 보상이 어렵게 된다. 둘째는 피라미드의 계층적 구조 모순으로 상위 계층예서 잘못된 움직임 추정(motion estimation)은 하위 계층으로 진행될수록 막대한 성능 저하의 원인이 된다. 본 논문에서는 우선 대역분할 부호화 방식을 이용한 대역별 계층적 이동보상에 대한 수학적 분석을 하였으며, 이를 바탕으로 제안되었던 통과 대역(pass-band) 이동보상 피라미드 방식이 누적된 양자화 오차 요인이 제거됨으로서 기존의 저대역 이동보상 피라미드에 비해 성능이 우수하다는 것을 이론적으로 분석하여 이를 증명하였다. 또한 계층적 이동보상 피라미드에서 매우 중요한 최고 계층의 초기 이동벡터 추정을 위하여 에지 패턴 분류를 이용한 이동벡터 추정 방식을 새로이 제안하였으며, 실험 결과 성능의 우수함이 입증되었다.

• 한국해양공학회지
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• 제10권3호
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• pp.62-73
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• 1996

Numerical simulation is made of the three-dimensional wave breaking motion about a part of a floating offshore structure containing a circular cylinder mounted vertically onto a lower hull in regular periodic gravity wave generated by a numerical wave maker. TUMMAC-VIII finite-difference method is newly developed for such a problem. By use of density-function technique the three-dimensional wave breaking motion is approximately implenented in the framework of rectangular grid system. A porosity technique is devised for the implementation of the no-slip bydy boundary conditions. The generation of breaking waves by the interaction of incident waves with the structure is well simulated and interesting features of breaking waves are revealed with containing degree of quantitative and qualitative accuracy.

• Computers and Concrete
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• 제29권3호
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• pp.201-207
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• 2022

The evaluation of velocity profile for large values of buoyancy parameter and Bioconvected Rayleigh number is examined. The non-linear problem has been tackled numerically by shooting technique. Nanofluid temperature and nanoparticle concentration slightly elevates for increasing values of thermophoresis coefficient. Thickness of thermal boundary layer is significantly increased with thermophoresis coefficient whereas thickness of concentration boundary layer is more slightly enhanced. The response of temperature and nanoparticles concentration is observed due to change in Brownian motion parameter. As Brownian motion parameter increased temperature distribution is slightly enhanced. The reverse behavior is observed in case of nanoparticles concentration. Comparison of numerical technique with the extant literature is made and an acceptable agreement is attained.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1245-1248
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• 2004

This paper presents a new technique to analyze data on the coordinate x, y, z and apply these data to design the motion control to improve the efficiency of the engraving machine so that it can engrave accordingly in 3 dimensions. First, the tool path on the x-y plane is analyzed to be synchronized with the z-axis. The digital data is then sent to the motion control to guide the movement of the engrave point on the x-y plane. Tool path moves along the x-axis with zero degree and different values of the y-axis according to the coordinate of the digital data and the analysis along z-axis to determine the depth for engraving. The depth can be specified from the gray level with the 256 levels of resolution. The data obtained includes the distances on x-axis, y-axis, and z-axis, the acceleration of the engrave point's movement, and the speed of the engrave point's movement. These data is then transfered to the motion control to guide the movement of the engrave point along the z-axis associated with the x-y plane. The results indicate that engraving using this technique is fast and continuous. The specimen obtained looks perfect in 3D view.

• Wind and Structures
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• 제1권1호
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• pp.43-57
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• 1998

A three-degree-of-freedom base hinged assembly (BHA) for aeroelastic model tests of tall building was developed. The integral parts of a BHA, which consists of two perpendicular plane frames and a flexural pivot, enable this modeling technique to independently simulate building translational and torsional degree-of-freedom. A program of wind tunnel aeroelastic model tests of the CAARC standard tall building was conducted with emphasis on the effect of (a) torsional motion, (b) cross-wind/torsional frequency ratio and (c) the presence of an eccentricity between center of mass and center of stiffness on wind-induced response characteristics. The experimental results highlight the significant effect of coupled translational-torsional motion and the effect of eccentricity between center of mass and center of stiffness on the resultant rms acceleration responses in both along-wind and cross-wind directions especially at operating reduced wind velocities close to a critical value of 10. In addition, it was sound that the vortex shedding process remains the main excitation mechanism in cross-wind direction even in case of tall buildings with coupled translational-torsional motion and with eccentricity.

• Journal of Information Display
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• 제5권3호
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• pp.1-7
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• 2004

We developed a novel frame interpolation method to interpolate a frame between two successive original frames. Using this method, we are able to apply a double-rate driving method instead of an impulse driving method where a black frame is inserted between two successive original frames. The double-rate driving method enables amelioration of the motion blur of LCDs caused by the characteristics of human vision without reducing the luminosity of the whole screen. The image quality of the double-rate driving method was also found to be better than that of an impulse driving method using our motion picture simulator and an actual panel. Our initial model of our frame interpolation method consists of motion estimation with a maximum matching pixel count estimation function, an area segmentation technique, and motion compensation with variable segmentation threshold. Although salt and pepper noise remained in a portion of an object mainly due to inaccuracy of motion estimation, we verified the validity of our method and the possibility of improvement in hold-type motion blurring.

• 전자공학회논문지B
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• 제30B권2호
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• pp.59-68
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• 1993

The motion vector estimation and motion boundary detection have been briskly studied since they are an important clue for analysis of object structure and 3-d motion. The purpose of this researches is more exact estimation, but there are two main causes to make inaccurate. The one is the erroneous measurement of gradients in brightness values and the other is the blurring of motion boundries which is caused by the smoothness constraint. In this paper, we analyze the gradient measurement error of conventional methods and propose new technique based on it. When the proposed method is applied to the motion boundary detection in Schunck and motion vector estimation in Horn & Schunck, it is shown to have much better performance than conventional method is some artificial and real image sequences.

• 한국정보처리학회논문지
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• 제7권5호
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• pp.1570-1578
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• 2000

Object motion is an important feature of content in video sequences. By now, various methods to exact feature about the object motion have been reported[1,2]. However they are not suitable to index video using the motion, since a lot of bits and complex indexing parameters are needed for the indexing [3,4] In this paper, we propose object motion map which could provide efficient indexing method for object motion. The proposed object motion map has both global and local motion information during an object is moving. Furthermore, it requires small bit of memory for the indexing. to evaluate performance of proposed indexing technique, experiments are performed with video database consisting of MPEG-1 video sequence in MPEG-7 test set.