• Korean Journal of Applied Biomechanics
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• v.17 no.3
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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.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.991-1000
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• 2019

The flying-disc game has started since 1940. It has been spreading rapidly in Korea since 2007, mainly in elementary schools. Additionally, as sports science has been developed, research on flying discs has been continued to build a monitoring system for technological improvement and efficiency. In this paper, we acquire information on the user's flying-disc using 9-axis motion sensor and GPS. Then we propose a method for wireless transmission using Bluetooth 5.0. Specifically, the HW platform was designed and implemented not only to monitor a real-time data but also to compare and analyze rotational speed, flight trajectory, and a count of disc rotation through post-processing.

• Smart Structures and Systems
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• v.9 no.6
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• pp.535-547
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• 2012

Controlling the balance of motion in a context involving a biped robot navigating a rugged surface or a step is a difficult task. In the present study, a $3{\times}5$ flexible piezoelectric tactile sensor array is developed to provide a foot pressure map and zero moment point for a biped robot. We introduce an innovative concept involving structural electrodes on a piezoelectric film in order to improve the sensitivity. The tactile sensor consists of a polymer piezoelectric film, PVDF, between two patterned flexible print circuit substrates (FPC). Additionally, a silicon rubber bump-like structure is attached to the FPC and covered by a polydimethylsiloxane (PDMS) layer. Experimental results show that the output signal of the sensor exhibits a linear behavior within 0.2 N ~ 9 N, while its sensitivity is approximately 42 mV/N. According to the characteristic of the tactile sensor, the readout module is designed for an in-situ display of the pressure magnitudes and distribution within $3{\times}5$ taxels. Furthermore, the trajectory of the zero moment point (ZMP) can also be calculated by this program. Consequently, our tactile sensor module can provide the pressure map and ZMP information to the in-situ feedback to control the balance of moment for a biped robot.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.912-928
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• 2019

Crowd behavior analysis research has revealed a central role in helping people to find safety hazards or crime optimistic forecast. Thus, it is significant in the future video surveillance systems. Recently, the growing demand for safety monitoring has changed the awareness of video surveillance studies from analysis of individuals behavior to group behavior. Group detection is the process before crowd behavior analysis, which separates scene of individuals in a crowd into respective groups by understanding their complex relations. Most existing studies on group detection are scene-specific. Crowds with various densities, structures, and occlusion of each other are the challenges for group detection in diverse crowded scenes. Therefore, we propose a group detection approach called Collective Interaction Filtering to discover people motion interaction from trajectories. This approach is able to deduce people interaction with the Expectation-Maximization algorithm. The Collective Interaction Filtering approach accurately identifies groups by clustering trajectories in crowds with various densities, structures and occlusion of each other. It also tackles grouping consistency between frames. Experiments on the CUHK Crowd Dataset demonstrate that approach used in this study achieves better than previous methods which leads to latest results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.902-910
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• 2018

This paper deals with spacecraft intercept problem on non-coplanar elliptical obit considering J2 perturbation. This disturbance addressed in this work is a major factor changing the trajectory of a spacecraft orbiting the Earth. To resolve this issue, a real-time intercept method is proposed. This method is based on the optimization problem which consist of the equation of motion considering spherical earth and impulse, and the optimal solution numerically obtained is set as the direction of the thrust of the interceptor. The position error is resolved by iteratively solving the optimization problem and modifying the direction of thrust of interceptor. The proposed method in this paper is verified by using various numerical examples.

• Journal of information and communication convergence engineering
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• v.20 no.2
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• pp.103-112
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• 2022

The goal of pattern mining is to identify novel patterns in a database. High utility itemset mining (HUIM) is a research direction for pattern mining. This is different from frequent itemset mining (FIM), which additionally considers the quantity and profit of the commodity. Several algorithms have been used to mine high utility itemsets (HUIs). The original BPSO algorithm lacks local search capabilities in the subsequent stage, resulting in insufficient HUIs to be mined. Compared to the transfer function used in the original PSO algorithm, the V-shaped transfer function more sufficiently reflects the probability between the velocity and position change of the particles. Considering the influence of the acceleration factor on the particle motion mode and trajectory, a nonlinear acceleration strategy was used to enhance the search ability of the particles. Experiments show that the number of mined HUIs is 73% higher than that of the original BPSO algorithm, which indicates better performance of the proposed algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.94-104
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• 1996

This paper presents a new approach to the design of adaptive control system using DSPs(TMS320C31) for robotic manpulators to achieve accurate trajectory tracking by the joint angles Digital signal processors are used in implementing real time adaptive control algorithms to provide an enhanced motion control for robotic manipulators. In the proposed contorl scheme, adaptation laws are derived from the improved Lyapunov second stability analysis method based on the adaptive model reference control theory. The adaptive controller consists of an adaptive feedforward controller, feedback controller, and PID type time varying auxillary control elements. The proposed adaptive control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Morever, this scheme does not require an accurate dynamic modeling nor values of manpipulator parameters and payload. Performance of the adaptive controller is illustated by simulation and experimental results for a SCARA robot.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.2
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• pp.159-170
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• 2023

In the present study, the dynamic behavior characteristics of an amphibious assault vehicle during water entry were analyzed using STAR-CCM+, a commercial computational fluid dynamics(CFD) code. All computations were performed using an overset mesh system and a RANS based flow-solver coupled with dynamic fluid-body interaction(DFBI) solver for simulating three degrees of freedom motion. For numerical validation of the solver, a water entry simulation of inclined circular cylinder was conducted and it was compared between an existing experiment data and CFD results. The pitch angle variation and the trajectory of the circular cylinder during water entry shows good agreement with previous experimental and numerical studies. For the water entry simulations of the amphibious assault vehicle, the analysis of dynamic behaviors of the amphibious assault vehicle with different slope angles, submerged depths and initial velocities were conducted. It is confirmed that the steep slope angle increases the submerged volume of the amphibious assault vehicle, so the buoyancy acting on the vehicle is increased and the moved distance for the re-flotation is decreased. It is also revealed that the submerged volume is increased, bow-up phenomenon occur earlier.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.383-386
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• 2022

본 논문에서는 COVID-19와 같은 위급한 상황에서 바이러스 검사를 빠르게 진행하기 위한 K-d 트리 기반의 그래프 구축과 환자 이동 경로 시스템을 제안한다. 가상환경에서 활용되는 대표적인 길 찾기 알고리즘은 A^*나 NavMesh 자료구조는 정해진 정적 이동 경로만을 안내하려는 방법이기 때문에 가상환경에서 NPC를 제어할 때는 효율적이지만, 실제 환경에 적용하여 문제를 풀기에는 충분하지 않다. 특히, 빠른 바이러스 검사를 받기 위해서는 짧은 거리만을 이용하는 게 아닌, 실제 도로 교통상황, 병원의 크기, 환자 이동 수, 환자 처리 시간 등 고려해야 할 상황들이 많다. 본 논문에서는 위에서 언급한 다양한 속성들과 이를 이용한 최적화 함수를 모델링하여, 실제 도시 맵에서 바이러스 검사를 빠르고 효율적으로 제어할 수 있는 프레임워크를 제안한다.

• Journal of Korea Game Society
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• v.6 no.2
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• pp.3-12
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• 2006

Recently, Many 3D augmented reality games that provide strengthened immersive have appeared in the 3D game environment. In this article, we describe a barehanded interaction method based on human hand gestures for augmented reality games. First, feature points are extracted from input video streams. Point features are tracked and motion of moving objects are computed. The shape of the motion trajectories are used to determine whether the motion is intended gestures. A long smooth trajectory toward one of virtual objects or menus is classified as an intended gesture and the corresponding action is invoked. To prove the validity of the proposed method, we implemented two simple augmented reality applications: a gesture-based music player and a virtual basketball game. In the music player, several menu icons are displayed on the top of the screen and an user can activate a menu by hand gestures. In the virtual basketball game, a virtual ball is bouncing in a virtual cube space and the real video stream is shown in the background. An user can hit the virtual ball with his hand gestures. From the experiments for three untrained users, it is shown that the accuracy of menu activation according to the intended gestures is 94% for normal speed gestures and 84% for fast and abrupt gestures.