• 전자공학회논문지S
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• 제36S권12호
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• pp.85-96
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• 1999

많은 경우의 예측 비디오 압축 표준에서는, BMA에 의해 매크로 블록당 하나의 움직임 벡터가 계산되는 방식인 BMC방식이 널리 사용되고 있다. 그러나 BMC에 의해 예측된 움직임 벡터 필드는 블록당 하나의 움직임 벡터를 사용하기 때문에 불연속적이며, 불연속적인 움직임 벡터 필드로 인해 블록화 현상을 나타낸다. 따라서 이를 제거하는 효과적인 방법은 움직임 벡터 필드를 평활화(smoothing)하는 방법일 것이다. 최적 평활화 과정은 비디오 시퀀스의 움직임 종류에 따라 다를 것이다. 본 논문에서는 움직임 벡터를 평활화하는 몇 개의 방법들을 고려할 것이다. 어떠한 방법이든 BMA로 구한 움직임 벡터는 더 이상 최적화된 움직임 벡터가 아닐 것이므로, BFD(displaced frame difference)의 놈(norm)을 최소화하는 최적 움직임 벡터를 찾아야 한다. 본 논문에서는 conjugate gradient 알고리즘을 사용하여 DFD의 놈을 최소화하는 최적움직임 벡터를 찾는 통합 알고리즘을 제안한다. 이 통합 알고리즘은 ATMC(affine transform based motion compensation), BTMC(bilinear transform based motion compensation), 그리고 본 논문에서 제안하는 FMC(filtered motion compensation)의 세가지 방식에 대하여 적용되고 BMC에 대비해서 평가되어 졌다.

• 대한조선학회논문집
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• 제54권6호
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• pp.461-469
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• 2017

A segment of the wave board has been expressed as a submerged line segment in the two dimensional wave flume. The lower end of the line segment could be extended to the bottom of the wave flume and the other opposite upper end of the board could be extended to the free surface. It is assumed that the motion of the wave board could be defined by the sinusoidal motion in horizontal direction on either end of the wave board. When the amplitude of sinusoidal motion of the wave board on lower and upper end are equal, the wave board motion could express the horizontally oscillating submerged segment of piston type wave generator. The submerged segment of flap type wave generator also could be expressed by taking the motion amplitude differently for the either end of the board. The pivot point of the segment motion could play a role of hinge point of the flap type wave generator. Simplified analytic solution of oscillating submerged wave board segment in water of finite depth has been derived through the first order perturbation method at two dimensional domain. The case study of the analytic solution has been carried out and it is found out that the solution could be utilized for the design of wave generator with arbitrary shape by linear superposition.

• 한국운동역학회지
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• 제30권1호
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• pp.7-16
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• 2020

Objective: It is to find factors related to stability through analysis of plantar pressure factors according to the level of instability when performing Snatch. Method: Foot pressure analysis was performed while 10 weightlifters performed 80% of the highest level of Snatch, and motion was classified and analyzed in 3 grades according to the level of instability. Results: First, in Bad Motion, the movement distance of the pressure center in the direction of ML and AP was larger significantly in Phase 2. Second, in Phase 2, the number of zero-crossing in the AP direction was larger statistically significantly in Good Motion. Third, in the bad motion in Phase 3, the number of zero-crossing in the ML direction showed a significantly larger value. Fourth, in Phase 4, it was found that the more stable the lock out motion, the greater the activity of foot controlling in the left and right directions. Fifth, Phase 3, the greater the Maximum/Mean foot pressure value, the more stable the pulling action. Sixth, in Phase 2, the foot pressure was concentrated with a wide distribution in the midfoot and rearfoot. Seventh, the triggering number of the forefoot region was small in the last pull phase. Eighth, the number of triggers in the toe area was significantly higher during Good Motion in Phase 4. Conclusion: Summarizing the factors of instability in Snatch, there was no significant difference in Phase 1 for each condition. In order to enhance the stability in Phase 2, the sensory control ability in the AP direction is required, and focusing the foot pressing motion with a wide distribution in the middle and rear parts increases the instability. In Phase 3, it was found that the more unstable, the more sensory control activity was performed in the ML direction, the stronger the forefoot pressing action should be performed for a stable Snatch. In Phase 4, It is important that the feet sensory control activity in ML directions and the control ability of the toes in order to have stable Lock out motion.

• 한국운동역학회지
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• 제15권2호
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• pp.119-127
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• 2005

The purpose of this research helps to make full use for perfect performance by grasping the defects of Ropez motion performed by athlete CSM who was under the training for the 28th 2004 Athene Olympic Garnes, and by presenting complementary methods. For the better Ropez motion which had been performed by CSM for the 1st dispatch selection test and the final for the 28th Athene Olympic Game was analyzed with 3-dimensional cinematographic method. Here are the conclusions: 1. During the board contact phase, powerful kicking and rapid forward flexion motion of upper body make increasing vertical velocity of C. O. G and enlarging body angle. 2. It was indicated that rapid forward flexion motion of upper body during the board contact phase get a large body angle in horse take-off. 3. rapid forward flexion motion of upper body during the board contact phase makes a longer time at horse contacting phase. It showed that this result increased velocity of horse take-off causing by powerful blocking motion. 4. Increasing of air-borne height during pre- flight phase, makes a higher C. O. G; and larger angle of hip, angle of knee and body angle in the landing phase. And it revealed that these results have a stable landing.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.9-16
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• 2002

The particles velocity in the instantaneous flow field and velocity change of particles along the jet centerline for various particle diameter in a circular turbulent impingement jet are investigated by using particle image velocimetry(PIV) and an equation of particle motion simplified by terms of inertia forces, drag and gravitational force. The jet Reynolds number was 3300 and 8700, and glass beads of 30,58 and 100$\mu$m in diameter were used. The PIV results show that the direction and size of velocity depends not only on the number density of particle but also on the particle momentum. The results obtained form calculation suggest that the particle velocity near the first impingement region deviated from local air velocity, which accords well with the PIV results. The rebound height of particle increase with the particle diameter. In the second-impingement, particle velocities increased sluggishly with Re=3300 but particle velocities uniformed with Re=8700 in stagnation region.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1933-1936
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• 2005

The isometric area of the anterior cruciate ligament was calculated during knee flexion-extension. Flexion-extension motion data of the joint were obtained using Fastrak and a three-dimensional motion measurement system. A total of five subjects were seated on a flat table and the tibia sensor position was measured with the femur fixed on the table. A three-dimensional knee model was constructed using a graphic tool to simulate the knee motion. Twenty seven positions of the tibia region and forty two positions of the femur region were selected and the distances between the determined tibial and femoral points were calculated. Highly isometric areas were found and displayed as three dimensional aspects.

• 한국가시화정보학회지
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• 제8권3호
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• pp.41-48
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• 2010

A visualization study to evaluate bubble motion in a tab water filled cylindrical tank with a varying flow rate of compressed air is conducted. The flow rate of compressed air varies from 1 to 5 L/min. Time resolved images are acquired by a high speed camera in 10 bit gray level at 100 fps and the measurement volume is irradiated by a 230 W halogen lamp. It is observed that there are three different regions; the bubble formation region, the rising bubble region and the free surface region. During the rise of bubble, the shape is changed as if an elastic body. Based on the binarized bubble image, the mean diameters of rising bubbles are estimated at beneath of the free surface. As the gas flow rate increases, the mean diameter is increased and the rising velocity also increases with buoyancy force.

• 한국정밀공학회지
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• 제21권9호
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• pp.188-195
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• 2004

Severe osteoarthrosis of the knee joint often requires total knee arthroplasty(TKA) to yield adequate knee function. The knee joint with TKA is expected ideally to restore the characteristics, however, this is not necessarily 1.ue in the clinical cases. In this study the motion of the intact joint and the joint after. TKA were investigated numerically using computer simulation. For active knee extension from 90 degrees of flexion to full extension, the intact knee joint exhibited anterior tibial translation near the full extension and it showed only rotation at other flexion angles. Physiologic external rotation of the tibia near full extension known as screw home movement was also noted in the analytical model. The analysis of the tibial insert of three different shapes (flat, semicurved, and curved types) demonstrated characteristic rotational and sliding motion as well as different contact forces.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.1-6
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• 2008

본 연구에서는 게임에서의 몰입도 증가를 위해 기존 버튼 방식의 입력에 사용자의 자연스러운 동작을 이용한 입력과 진동 촉감을 출력하는 게임 컨트롤러를 제안한다. 동작을 이용한 입력장치는 가속도 추적기와 적외선 비디오 카메라를 동시에 사용한다. 두 정보의 장단점을 보완/융합해서 컨트롤러의 움직임을 추적하고, 사용자의 동작을 인식한다. 다양한 종류의 진동촉감은 보이스코일 진동자를 이용하여 제공된다. 또한, 제안하는 게임 컨트롤러를 게임의 상호작용에 적용하는 방법을 제공하고, 응용 프로그램에의 적용가능성을 살펴본다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.507-514
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• 2001

Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.