• 전기학회논문지
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• 제66권9호
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• pp.1385-1391
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• 2017

This work presents a synchronized on-line trajectory generation algorithm for mechanical system with multiple degrees-of-freedom. Proposed algorithm is designed to generate time-optimized trajectories and synchronized trajectories under the constraints such as maximum speed, acceleration, deceleration, non-zero initial velocity, etc. Also, because of small computation time, therefore this can be applied in real-time and it is easier to change the trajectory when an event occurs. We verified the feasibility through various trajectory generation.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.533-545
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• 2017

Massive volumes of GPS trajectory data bring challenges to storage and processing. These issues can be addressed by compression algorithm which can reduce the size of the trajectory data. A key requirement for GPS trajectory compression algorithm is to reduce the size of the trajectory data while minimizing the loss of information. Synchronized Euclidean distance (SED) as an important error measure is adopted by most of the existing algorithms. In order to further reduce the SED error, an improved algorithm for open window time ratio (OPW-TR) called local optimum open window time ratio (LO-OPW-TR) is proposed. In order to make SED error smaller, the anchor points are selected by calculating point's accumulated synchronized Euclidean distance (ASED). A variety of error metrics are used for the algorithm evaluation. The experimental results show that the errors of our algorithm are smaller than the existing algorithms in terms of SED and speed errors under the same compression ratio.

• 한국항공운항학회지
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• 제30권4호
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• pp.1-8
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• 2022

In this study, we propose trajectory-based arrival management using CDO (Continuos Descent Operations). The operational procedures with TBO (Trajectory-Based Operations) concept were established to allow aircraft and ground system to share the trajectories with each other in real time. The proposed operational concept was validated in the air traffic control simulation environment, which consists of controller working position, pseudo pilot system, air traffic generation system, and controllers' decision support system for arrival management using CDO. Simulation results compared with actual flight data indicate that proposed concept could improve the efficiency of traffic flow management in terms of total descending time and fuel consumption. And it was confirmed that if there is a system that can share and utilize the synchronized trajectory, it can be helpful to control arrival aircraft and apply CDO concept.

• 제어로봇시스템학회논문지
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• 제10권12호
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• pp.1233-1240
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• 2004

Recently the need for cooperative control among robots is increasing in a variety of industrial robot applications. Such a control framework enhances the efficiency of the real robotic assembly environment along with extending the robot application. In this paper, an ethernet-based cooperative control framework was proposed. The cooperative control of robots can multiply the handling capacity of robot system, and make it possible to implement jigless cooperation, due to realization of trajectory-synchronized movement between a master robot and slave robots. Coordinate transformation was used to relate among robots in a common coordinate. An optimized ethernet protocol of HiNet was developed to maximize the speed of communication and to minimize the error of synchronous movement. The proposed algorithm and optimization of network protocol was tested in several class of robots.

• 대한기계학회논문집B
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• 제29권12호
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• pp.1360-1368
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• 2005

This study investigates the characteristics of spray, such as evaporation rate and spray trajectory, for a 4-hole injector which is applied to a 4-valve motorcycle gasoline engine. Three dimensional, unsteady, compressible flow and spray within the intake-port and cylinder have been simulated using the VECTIS code. Spray characteristics were investigated at 6000 rpm engine speed. Furthermore, we visualized fuel behavior in the intake-port using a CCD camera synchronized with a stroboscope in order to compare with the analytical results. Boundary and intial conditions were employed by complete 1-D simulation of the engine using the WAVE code. Fuel was injected into the intake-port at two time intervals relative to the position of the intake valves so that the spray arrived when the valves were closed and fully open. The results showed that the trajectory of the spray was directed towards the lower wall of the port with injection against the closed valves. With open valve injection, a large portion of the fuel was lifted by the co-flowing air towards the upper half of the port and this was confirmed by simulation and visualization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.713-728
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• 2021

This paper proposes an augmented reality technique to generate acrobatic scenes from hitting motion videos. After a user shoots a motion that mimics hitting an object with hands or feet, their pose is analyzed using motion tracking with deep learning to track hand or foot movement while hitting the object. Hitting position and time are then extracted to generate the object's moving trajectory using physics optimization and synchronized with the video. The proposed method can create videos for hitting objects with feet, e.g. soccer ball lifting; fists, e.g. tap ball, etc. and is suitable for augmented reality applications to include virtual objects.

• 한국컴퓨터정보학회논문지
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• 제25권5호
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• pp.19-26
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• 2020

본 논문에서는 다양한 사용자의 영상을 이용하여 축구공 리프팅과 같은 묘기 장면을 만들 수 있는 프레임워크를 제안한다. 제안된 방법은 핸드폰 등으로 촬영된 일반적인 사용자의 영상이라면 수 초 이내에 원하는 결과를 생성할 수 있다. 본 논문의 프레임워크는 크게 세 부분으로 나누어진다. 첫 번째는 사용자의 영상을 입력받아 자세를 분석하는 것이다. 이를 위해서는 딥러닝 기법으로 영상을 분석하여 사용자의 포즈를 계산하고, 원하는 신체 부위의 움직임을 추적할 수 있다. 두 번째는 지정된 신체부위의 이동 궤적을 분석하여 물체를 타격하는 위치와 시간을 계산하는 것이다. 마지막으로 분석된 타격 정보를 이용하여 물체의 이동 궤적을 생성하는 것이다. 그러면 입력된 사용자 영상과 동기화되는 자연스러운 물체 리프팅 장면을 생성할 수 있다. 사실적인 물체의 움직임을 생성하기 위해 물리 기반 최적화를 사용하였다. 본 논문의 프레임워크를 이용하면 다양한 증강현실 어플리케이션을 제작할 수 있다.

• 한국정밀공학회지
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• 제22권6호
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• pp.213-221
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• 2005

An insole type local shear force measurement system was developed and local shear stresses in the foot were measured during level walking. The shear force transducer based on the magneto-resistive principle, was a rigid 3-layer circular disc. Sensor calibrations with a specially designed calibration device showed that it provided relatively linear sensor outputs. Shear transducers were mounted on the locations of four metatarsal heads and heel in the insole. Sensor outputs were amplified, decorded in the bluetooth transmission part and then transferred to PC. In order to evaluate the developed system, both shear and plantar pressure measurements, synchronized with the three-dimensional motion analysis system, were performed on twelve young healthy male subjects, walking at their comfortable speeds. The maximum peak pressure during gait was 5.00kPa/B.W at the heel. The time when large local shear stresses were acted correlated well with the time of fast COP movements. The anteroposterior shear was dominant near the COP trajectory, but the mediolateral shear was noted away from the COP trajectory. The vector sum of shear stresses revealed a strong correlation with COP movement velocity. The present study will be helpful to select the material and to design of foot orthoses and orthopedic shoes for diabetic neuropathy or Hansen disease.

• 지능정보연구
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• 제29권2호
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• pp.115-127
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• 2023

동영상 안정화 기술은 최근 1인 미디어 시장이 거대화됨에 따라 그 중요성이 점점 커지고 있는 카메라 기술 중 하나이다. 딥러닝 기반의 기존 방법들에서는 안정화 전/후 동영상 데이터 쌍을 사용하였으나 동영상의 특성상 동기화된 안정화 전/후 데이터를 만드는 것은 많은 시간과 노력이 필요하다. 최근 이러한 문제를 완화하기 위하여 안정화 전 데이터만을 사용하는 비지도 학습 방법이 제시되고 있다. 본 논문에서는 비지도 학습 방법의 하나인 Convolutional Autoencoder 구조를 사용하여 안정화 전/후 동영상 데이터 쌍 없이 안정화 전 영상만으로 안정화 궤적을 학습하는 네트워크 구조를 제안한다. 네트워크 입력 및 출력으로 옵티컬 플로우를 사용하고 네트워크 경량화 및 노이즈 최소화를 위해 옵티컬 플로우를 Grid 단위로 맵핑하여 사용했다. 또한 비지도 학습 방법으로 안정화된 궤적을 생성하기 위해 옵티컬 플로우를 부드럽게 만드는 손실함수를 정의하였고 결과 비교를 통해 손실함수의 의도대로 부드러운 궤적을 생성하도록 네트워크가 학습되었음을 확인했다.

• 한국운동역학회지
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• 제17권3호
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• pp.125-131
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• 2007

The purpose of this study was to evaluate the difference in grip force and angular kinematic variables between elite (handicap${\leq}2$) and novice golfers. Three-dimensional motion analysis system with synchronized grip force measurement system was used. The participants consisted of two groups based on their playing ability: 10 elite golfers and 10 novice golfers. Each subject performed 5 putting strokes at the distance of 1, 3, and 5m with randomly selected order. During entire putting phase, elite group showed relatively constant grip force but novice group showed continuously increasing grip force pattern. There existed a clear difference in the trajectory of shoulder line between two groups. As for novice group the rotational center did not converge into one point, for elite group the rotational center converged into precise single point. And there was a clear difference pattern in anterior-posterior directional movement at shoulder between two groups. These difference might be helpful for improving consistent putting skills.