• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1621-1624
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• 2003

This paper presents a new method that generates a path that has no collision with the obstacles or the characters by using the three motion parameters, and automatically creates natural motions of characters that are confined to the path. Our method consists of three parameters: the joint information parameter, the behavior information parameter, and the environment information parameter. The joint information parameters are extracted from the joint angle data of the character and this information is used when creating a path following motion by finding the relation-function of the parameters on each joint. A user can set the behavior information parameter such as velocity, status, and preference and this information is used for creating different paths, motions, and collision avoidance patterns. A user can create the virtual environment such as road and obstacle, also. The environment is stored as environment information parameters to be used later in generating a path without collision. The path is generated using Hermit-curve and each control point is set at important places.

• Journal of the Ergonomics Society of Korea
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• v.15 no.2
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• pp.125-135
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• 1996

The purpose of this research is to measure range of virtual hip joint and lower limb joints motion such as the hip, knee and ankle joints for 47 young male students. The results of ANOVA revealed that anthropometric dimensions including weight and stature did not show any significant effects on the range of virtual hip joint and lower limb joints motion and the range of motion with two degrees of freedom at the shoulder, virtual hip and hip joints. Anthropometric dimensions such as age, weight, statuire, arm length, shoulder height and leg length were found to be lowly correlated with the range of virtual hip joint and lower limb joints motion. It is expected that the data on the range of joint motion suggested in this study can be used as a valuable input data when designing workplace, predicting human posture and reach volume, etc.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.631-634
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• 2001

In this study, the graphic simulation system of multi joint manipulator is developed to analyze and optimize the remote handling processes for the spent fuel assembly. This system consists of a 3-D graphical modeling system, a device assembling system, and a motion simulation system. To analyze and optimize the processes involved in multi-joint manipulator operation such as NFBC transportation process and bottom nozzle removal process, the virtual work place is implemented using a computer graphic technology. This virtual workcell is exactly same as that of the real environment. This graphic simulation system of the multi-joint manipulator can be effectively used for designing the main processes and maintenance processes of the spent fuel management.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.670-677
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• 2011

This study is to estimate the joint torques without torque sensor using the EMG (Electromyogram) signal of agonist/antagonist muscle with Neural Network Back Propagation Algorithm during the elbow motion. Command Signal can be guessed by EMG signal. But it cannot calculate the joint torque. There are many kinds of field utilizing Back Propagation Learning Method. It is generally used as a virtual sensor estimated physical information in the system functioning through the sensor. In this study applied the algorithm to obtain the virtual senor values estimated joint torque. During various elbow movement (Biceps isometric contraction, Biceps/Triceps Concentric Contraction (isotonic), Biceps/Triceps Concentric Contraction/Eccentric Contraction (isokinetic)), exact joint torque was measured by KINCOM equipment. It is input to the (BP)algorithm with EMG signal simultaneously and have trained in a variety of situations. As a result, Only using the EMG sensor, this study distinguished a variety of elbow motion and verified a virtual torque value which is approximately(about 90%) the same as joint torque measured by KINCOM equipment.

• International Journal of Computer Science & Network Security
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• v.22 no.11
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• pp.241-247
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• 2022

Ad hoc network is self-organized network powered by battery. The reliability of virtual user identification and channel security are reduced when SNR is low due to limited user energy. In order to solve this problem, a joint virtual user identification and channel security en/decoding method is proposed in this paper. Transmitter-receiver-based virtual user identification code is generated by executing XOR operation between orthogonal address code of transmitter and pseudo random address code of receiver and encrypted by channel security code to acquire orthogonal random security sequence so as to improve channel security. In order to spread spectrum as well as improve transmission efficiency, data packet is divided into 6-bit symbols, each symbol is mapped with an orthogonal random security sequence. Subspace-based method is adopted by receiver to process received signal firstly, and then a judgment model is established to identify virtual users according to the previous processing results. Simulation results indicate that the proposed method obtains 1.6dB E_b/N₀ gains compared with reference methods when miss alarm rate reaches 10^-3.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.37-42
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• 2016

We investigate multi user joint rate scheduling and power allocation problem for a delay sensitive CDMA systems. First, we characterize the existing two user joint rate scheduling and power allocation. We then extend the problem to the case of the multi user systems. In general, there is no simple optimum solution for the multi user scheduling problem. To that end, we propose a sub optimum solution, termed 'virtual user approach'. We show the performance of the virtual user approach to verify the benefit of complexity.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.11
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• pp.904-911
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• 2001

A broomstick swinging biped acrobatic controller is designed and simulated to show capability of the system of controllers: virtual model controller is employed for the robot\`s posture balancing control while a higher level fuzzy controller modulate the one of the virtual model controller\`s parameter for the pendulum swinging motion generation. The robot is of 7 degree-of-freedom, 8-link planar bipedal robot having two slim legs and a body. Each leg consists of a hip joint, a knee joint, an ankle joint and the body has a free joint at the top in the head at which a freely rotating broomstick is attached. We assume that the goal for the acrobat robot is to maintain a body balance in the sagittal plane while swinging up the freely up the freely rotating pendulum. We also assume that the actuators in the joints are all ideal torque generators. The proposed system of controllers satisfies the goal and the simulation results are presented.

• Journal of the Ergonomics Society of Korea
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• v.15 no.2
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• pp.15-24
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• 1996

To generate workspace analytically using the robot kinematics, data on range of human joints motion, especially range of two degrees of freedom motion, are needed. However, these data have not been investigated up to now. Therefore, in this research, we are to investigate an interaction effect of motions with two degrees of freedom occurred simultaneously at the shoulder, virtual hip(L5/S1) and hip joints, respectively, for 47 young male students. When motion with two degrees of freedom occurred at a joint such as shoulder, virtual hip and hip joints, it was found from the results of ANOVA that the action of a degree of freedom motion may either decrease or increase the effective functioning of the other degree of freedom motion. In other words, the shoulder flexion was decreased as the shoulder was adducted or abducted to $60^{\circ}C$TEX>or abducted from $60^{\circ}C$TEX>to maximum degree of abduction, while the shoulder flexion increased as the joint was abducted from $60^{\circ}C$TEX> to $60^{\circ}C$TEX> The flexion was decreased as the virtual hip was bent laterally at the virtual hip joint, and also did as the hip was adducted or abducted from the neutral position. It is expected that workspace can be generated more precisely based the data on the range of two degrees of joint motion measured in this study.

• Physical Therapy Rehabilitation Science
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• v.9 no.3
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• pp.171-177
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• 2020

Objective: This study aimed to investigate the upper limb strength, active joint range of motion (AROM), and upper limb function in persons with chronic stroke using virtual reality training in combination with upper limb sensory stimulation. Design: Two-group pretest-posttest design. Methods: 20 subjects were divided into two groups of 10, the sensory motor stimulation and virtual reality training (SMVR) and virtual reality training (VR) groups. The training was conducted for 30 minutes per session, three times a week for 8 weeks.The participants' upper limb strength was measured via the hand-held dynamometer, joint angle AROM was measured via dual inclinometer, function was measured using the Jebson-Taylor hand function test and the manual function test. Results: Significant differences were observed in all groups before and after the training for upper extremity strength, AROM, and function (p<0.05). Between the two groups, the SMVR group showed significant improvement in muscle strength, AROM, and Jebsen-Taylor hand function test scores compared with the VR groups (p<0.05). Conclusions: In this study, we confirmed that sensory stimulation and VR had positive effects on upper extremity strength, AROM, and function of persons with chronic stroke. The results suggest that in the future, VR in combination with sensory stimulation of the upper limb is likely to become an effective method (a rehabilitation training program) to improve the upper limb function of persons with chronic stroke.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.55-62
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• 2014

PURPOSE: The objective of this study was to determine the effects of virtual reality training on muscle activation in the elderly. METHODS: The subjects were 32 healthy elderly people aged between 65 and 80, who were divided into the VR(virtual reality) training group(n=17) and the control group(n=15). The Virtual reality training group engaged in a 30-minute exercise session using Wii Fit three times a week for eight weeks. Virtual reality training group used the Ski Slalom, Table tile, Balance bubble programs. low-extremity muscle activation of the two groups were measured before and after the intervention. RESULTS: To investigate the effects of the training on lower-extremity muscle activation, biceps femoris, gastrocnemius, tibialis anterior, vastus lateralis were measured. The results revealed that the activation of gastrocnemius and tibialis anterior significantly increased(p<.05), which indicates virtual reality training is effective in improving the activation of the muscles involved in the movement of the ankle joint. CONCLUSION: Virtual reality training is effective in improving the healthy elderly's activation of the muscles involved in the movement of the ankle joint. Thus, virtual reality training can be proposed as a form of fall prevention exercise for the elderly.