• Journal of the Korean Society of Industry Convergence
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• v.20 no.1
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• pp.49-55
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• 2017

This study proposes a new approach to Control and trajectory generation of a 8 DOF human robot arm with computational complexity and singularity problem. To deal with such problems, analytical methods for a redundant robot arm have been researched to enhance the performance of research, we propose an analytical kinematics algorithm for a 8 DOF bipped dual robot arm. Using this algorithm, it is possible to generate a trajectory passing through the singular points and intuitively move the elbow without regarding to the end-effector pose. Performance of the proposed algorithm was verified by simulation test with various conditions. It has been verified that the trajectory planning using this algorithm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.71-76
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• 2007

The fatalities of pedestrian account for about 40.0% of all fatalities in Korea 2005. Vehicle-Pedestrian accident generates trajectory of pedestrian. In pedestrian involved accident, the most important data to inspect accident is throw distance of pedestrian. The throw distance of pedestrian can be influenced by many variables. The variables that influence trajectory of pedestrian can be classified into vehicular factors, pedestrian factors, and road factors. Vehicular factors are the frontal shape of vehicle, impact speed of vehicle, the offset of impact point. Many studies have been done about the relation between impact speed and throw distance of pedestrian. But the influence of the offset of impact point was neglected. The influence of the offset of impact point was analyzed by Working Model, and the trajectory of pedestrian, dynamic characteristics of multi-body were analyzed by PC-CRASH, a kinetic analysis program for a traffic accident. Based on the results, the increase of offset reduced the throw distance of pedestrian. However box type vehicle just like bus, the offset of impact point did not influence the throw distance of pedestrian considerably.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.85-91
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• 2004

The use of gestures provides an attractive alternate to cumbersome interface devices for human-computer interaction. This has motivated a very active research area concerned with computer vision-based analysis and interpretation of hand gestures The most important issues in gesture recognition are the simplification of algorithm and the reduction of processing time. The mathematical morphology based on geometrical set theory is best used to perform the processing. The key idea of proposed algorithm is to track a trajectory of center points in primitive elements extracted by morphological shape decomposition. The trajectory of morphological center points includes the information on shape orientation. Based on this characteristic we proposed the morphological gesture sequence recognition algorithm using feature vectors calculated to the trajectory of morphological center points. Through the experiment, we demonstrated the efficiency of proposed algorithm.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.4
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• pp.285-289
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• 2012

In a coastal area, all of the vessels are always exposed to the potential risk, taking into the maritime accident statistics account over the last decades. To manage vessels underway safety, the characteristics of ship movements in a fairway should be recognized by VTS system or VTS operators. The IMO has already mandated the shipboard carriage of AIS since 2004, as stated in SOLAS Chapter V Regulation 19. As a result, the static and dynamic information of AIS data has been collected for vessel traffic management in the coastal areas and used for VTS. This research proposes a simple algorithm of recognizing potentially risky ships by observing their trajectories on the fairway. The static and dynamic information of AIS data are collected and the curvature for the ship trajectory is surveyed. The proposed algorithm finds out the irregularity of ship movement. The algorithm effectively monitors the change of navigation pattern from the curvature analysis of ship trajectory. Our method improves VTS functions in an intelligent way by analyzing the navigation pattern of vessels underway.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.1
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• pp.43-51
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• 2010

Purpose : The purpose of this study was to compare plantar pressure distribution between affected side and unaffected side and to analyze plantar pressure distribution of affected side according to the extent of hemineglect in the adult hemiplegia. Methods : Twenty-five hemiplegia participated in this study. The analysis of plantar pressure distribution was conducted by the F-scan system, and the extent of hemineglect was evaluated with line-bisection test. While the subject walked about 10 meters in their comfortable speed the plantar pressure was evaluated and stored. Results : Total contact area, AP CoP trajectory, contact pressure of mid-foot of the affected side were significantly different from the unaffected side. Total contact area, AP CoP trajectory and contact pressure of mid-foot were smaller than those of unaffected side. In the comparison among the group according to the extent of hemineglect, AP CoP trajectory of subject who has severe hemineglect was significantly different from the patient that has no hemineglect and it was shorter than that of no hemineglect. Conclusion : The plantar pressure distribution was generally different between affected side and unaffected side and the hemineglect affected negatively the patient to move CoP forwardly while walking. Accordingly, it will help the clinician to understand the hemineglect which has an effect on abnormal walking and to intervent the hemiplegia who has a neglection to the affected side.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.20-29
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• 2018

The dynamic characteristics of power systems become more and more complex because of the integration of large-scale wind power, which needs appropriate control strategy to guarantee stable operation. With wide area measurement system(WAMS) creating conditions for realizing realt-ime transient stability analysis, a new coordinated control strategy for power system transient stability control based on phase-plane trajectory was proposed. When the outputs of the wind farms change, the proposed control method is capable of selecting optimal generators to balance the deviation of wind power and prevent transient instability. With small disturbance on the base operating point, the coordinated sensitivity of each synchronous generator is obtained. Then the priority matrix can be formed by sorting the coordinated sensitivity in ascending order. Based on the real-time output change of wind farm, coordinated generators can be selected to accomplish the coordinated control with wind farms. The results in New England 10-genrator 39-bus system validate the effectiveness and superiority of the proposed coordinated control strategy.

• Journal of IKEEE
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• v.27 no.4
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• pp.411-417
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• 2023

Unmanned aerial vehicle (UAV)-assisted relay has the advantages of ease of deployment, good communication channels, and mobility over traditional terrestrial relay, which greatly improves wireless connectivity. In this paper, we design a UAV-enabled relay network that can utilize radio frequency bands to harvest energy from sources and utilize terahertz (THz) bands to transmit information between secondary transmitters and receivers. Next, we solve the optimal position of the UAV that maximizes the relay channel capacity, and propose an algorithm to design two trajectories of UAV (a straight and an elliptical trajectory) using the derived solution. Numerical results show that the straight trajectory is better in terms of harvested energy and channel capacity.

• Journal of Preventive Medicine and Public Health
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• v.56 no.6
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• pp.495-503
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• 2023

Objectives: While older adults using community care services are known to be vulnerable for depression, community care utilization (CCU) may help to improve the mental health of these elderly. To date, however, it is much less clear how CCU affects depressive symptoms in the elderly population. This study focuses on the trajectory of depressive symptoms across years of CCU among older adults in Korea. Methods: Using the 2006-2019 Korean Welfare Panel Survey, this study is focused on elderly born in 1940 or earlier and selected 3281 persons for baseline interviews in 2006. This consisted of 35 800 person-year observations during a period of 14 years. Panel data analysis were employed to construct years of CCU. Results: After controlling for covariates, linear term of years using community care was negatively associated with depressive symptoms, but a quadratic term was positively significant. The trajectory of depressive symptoms across the years of CCU follows a U-shaped curve. Older adults in the first year of using community care reported the highest level of depressive symptoms. However, a significant and steady decrease in depressive symptoms was observed during the following 9 years of CCU, which then gradually increased. The level of depressive symptoms at the 14th year of using community care remains significantly lower than the level at the outset of its utilization. Conclusions: This finding implies that CCU could be beneficial for improving mental health among older adults.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.68-77
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• 2018

In order to analyze the overall characteristics of the lunar orbiter, the Variable Coast method, which can be launched everyday, is applied to the 3.5 phasing loop transfer trajectory. The mission scenario for the entire process from launching to entering the lunar orbit is set up and performed simulation by selecting the launch pad and launch vehicle. In particular, the SEM(Satellite-Earth-Moon) angle defined in Earth-Moon rotating frame is an important constraint to comprehensively evaluate the 3.5 phasing loop transfer trajectory. The simulation using SEM angle is analyzed from various viewpoints such as launch epoch, coast duration, perigee altitude and ${\Delta}V$ not only trans-lunar trajectory but lunar orbit insertions and the optimum SEM angle is suggested in this study. It is expected that this results will be helpful to evaluate the characteristics of the 3.5 phasing loop transfer trajectory according to the launch vehicle selection by comparison with Fixed Coast analysis results in the future.

• Journal of the Society of Disaster Information
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• v.17 no.3
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• pp.655-666
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• 2021

Purpose: This study is to develop a method for measuring dynamic speeding risks using vehicle trajectory big data and to demonstrate the feasibility of the devised speeding index. Method: The speed behaviors of vehicles were analysed in microscopic space and time using individual vehicle trajectories, and then the boundary condition of speeding (i.e., boundary speed) was determined from the standpoint of crash risk. A novel index for measuring the risk exposure of speeding was developed in microscopic space and time with the boundary speed. Result: A validation study was conducted with vehicle-GPS trajectory big data and ground-truth vehicle crash data. As a result of the analysis, it turned out that the index of speeding-risk exposure has a strong explanatory power (R²=0.7) for motorway traffic accidents. This directly indicates that speeding behaviors should be analysed at a microscopic spatiotemporal dimension. Conclusion: The spatial and temporal evolution of vehicle velocity is very variable. It is, hence, expected that the method presented in this study could be efficaciously employed to analyse the causal factors of traffic accidents and the crash risk exposure in microscopic space using mobility trajectory data.