• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.31-38
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• 2006

The purpose of this study was to investigate the effect of changing the steps height on the joint moment of lower extremity in stair-descent activity of elderly persons. Data were collected by 3-D cinematography and force platform. 9 male elderly subjects in the 60s and 70s participated in this study. All subjects performed a stair-descent in four different heights of stairs (10, 14, 18, 22cm) having 5 step staircase. The results were as follows. 1. For the step height of 22cm the maximum. plantarflexion moment was the smallest and the largest for the step height of 14cm. 2. There was not a statistical difference shown for the extension moment of the knee joint for the different height of steps. 3. There was not a statistical difference shown for the flexion moment of the hip joint for the varying height of steps but on average for the 18cm step this increased rapidly. 4. The smallest maximum. value for inversion moment was revealed for the step height of 10cm and this increased significantly for the step height of 22cm. 5. The smallest maximum. value for abduction moment of the hip joint was revealed for the step height of 10cm and this increased significantly for the step height of 22cm. 6. There was no significant difference shown for the maximum. abduction moment for the hip joint. The main conclusion is that there is a huge difference in the moment of the lower extremities for the elderly while walking down a stairs with a step height above 18 cm and that this moment increased or decreased rapidly under a condition of step height being 22cm. With the results from this research and related research of elderly walking upstairs it can be shown that the step height has a large role in the safety for the elderly.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.125-134
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• 2006

The purpose of this study was to analyze the Biomechanical elements by looking at the differences on the motions of the right and left spikes of right-handed offense volleyball players, using 3D image analysis and force platform. For that purpose, spike motions of six male university volleyball players were recorded three times each using two 16mm high speed cameras and the speed of recording was set at 60 frames/sec. The coordinated raw data was leveled as 6Hz using low pass filtering method and the calculation of 3D coordinates was done by using a DLT (Direct Linear Transformation) method. Also KWON 3D program was used to analyze the variables. Through the experiments and research, the following results were found: That is, in case of the right spike, the required time from the toss to the impact, which affected the success rate of offense showed as longer and on the take-off, the exact timing to touch the ball was longer because the pace between right and left feet was wider, and also after the jump, the distance between the feet indicated shorter, than the left. In addition, the degree of somersault and horizontal adduction of shoulder joint was smaller and the degree of medial rotation of shoulder joint showed bigger than the left, so it indicated that it was not centered on the body, but by the arm with an axis of shoulder using a swing motion. After the impact, the speed of the ball indicated slower compared to the left spike.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.161-167
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• 2016

Distribution channels are changing its industry paradigm from quantitative increase to qualitative improvement. In addition, it incorporates new characteristics and consumption tread of customers and the core value of service is developing focused around on online to offline (O2O) business model of omnichannel. In this respect, companies are integrating various distribution channels and in order to provide high content business service to customers, their interest in finding a new business strategy is increasing. Currently, most of the service being provided to customers are formed based on distribution structure centered around big companies and financial industry and the problems faced by small to medium and micro enterprises, which are expansion and improvement of channels, discovery of new distribution channels and finding O2O marketing strategy, can be said as very important task. Accordingly, this research purports to create added values which can serve as the driving force of growth of "creative economy" by improving distribution channels in which anyone who incorporates needs of smart consumers can enter into the smart commerce market and to further form sustainable win-win market that is strategic through business platforms for small to medium and micro enterprises therefrom.

• Journal of Ocean Engineering and Technology
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• v.32 no.1
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• pp.1-8
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• 2018

In order to analyze the response of the offshore structure numerically, the linear potential theory is generally applied for simplicity, and only the radiation damping is considered among various damping forces. Therefore, the results of a numerical simulation can be different from the motion of the structure in a real environment. To reduce the differences between the simulation results and experimental results, the viscous damping, which affects the motion of the structure, is also taken into account. The appropriate damping model is essential for the numerical simulation in order to obtain precise responses of the offshore structure. In this study, various damping models such as linear or quadratic damping and the nonlinear drag force from numerous slender bodies were used to simulate the free decay motion of the platform, and its characteristics were confirmed. The optimized damping model was found by comparing the simulation results to the experimental results. The hydrodynamic forces and wave exciting forces of the structure were obtained using WAMIT, and the free decay test was simulated using OrcaFlex. A free decay test of the scale model was performed by KRISO.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.2
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• pp.13-23
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• 2011

Purpose : The purpose of this study is to investigate the effect on the static balance ability according to vestibular training using ball. Methods : Twenty normal subjects participated and were randomly assigned to either a vestibular training group using ball or a control group. The vestibular training using a ball group exercised 3 times per week over 3 weeks. The static balance was assessed by the center of pressure to the stance position. The participants stood barefoot on a force platform in a normal stance and a one-legged stance with a visual close. Results : In the normal stance, there were no significant differences at CoP surface and CoP speed. However, in a one-legged stance, there were significant differences in the vestibular training group between before and after the program. There was also a significant difference between the vestibular training group and the control group. Conclusion : Vestibular training using ball can be implemented as a therapeutic intervention to improve static balance ability in health adults.

• Convergence Security Journal
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• v.6 no.4
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• pp.113-120
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• 2006

C4I system is the centerpiece of the military force. The system is an information based system which facilitates information grid, collection of data and dissemination of the information. The C4I system seeks to assure information dominance by linking warfighting elements in the battlespace to information network which enables sharing of battlespace information and awareness; thereby shifting concept of warfare from platform-centric paradigm to Network Centric Warfare. Although, it is evident that C4I system is a constant target from the adversaries, the issues of vulnerability via cyberspace from attack still remains. Therefore, the protection of C4I system is critical. The roadmap I have constructed in this paper will guide through the direction to protect the system during peace and war time. Moreover, it will propose vision, objectives and necessary supporting framework to secure the system from the threat. In order to fulfill these tasks, enhanced investments and plans from the Joint chief of Staff and Defense of Acquisition and Program Administration (DAPA) is critical; thereby enabling the establishment of rapid and efficient security system.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.3
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• pp.210-216
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• 2016

This paper presents a novel collision avoidance technique for mobile robots based on omni-directional vision simultaneous localization and mapping (SLAM). This method estimates the avoidance path and speed of a robot from the location of an obstacle, which can be detected using the Lucas-Kanade Optical Flow in images obtained through fish-eye cameras mounted on the robots. The conventional methods suggest avoidance paths by constructing an arbitrary force field around the obstacle found in the complete map obtained through the SLAM. Robots can also avoid obstacles by using the speed command based on the robot modeling and curved movement path of the robot. The recent research has been improved by optimizing the algorithm for the actual robot. However, research related to a robot using omni-directional vision SLAM to acquire around information at once has been comparatively less studied. The robot with the proposed algorithm avoids obstacles according to the estimated avoidance path based on the map obtained through an omni-directional vision SLAM using a fisheye image, and returns to the original path. In particular, it avoids the obstacles with various speed and direction using acceleration components based on motion information obtained by analyzing around the obstacles. The experimental results confirm the reliability of an avoidance algorithm through comparison between position obtained by the proposed algorithm and the real position collected while avoiding the obstacles.

• The Journal of Korean Physical Therapy
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• v.21 no.1
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• pp.19-25
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• 2009

Purpose: We investigated the changes that effects of load stimulation (LS) on static balance and muscle activities in normal healthy elders and chronic stroke patients. Methods: Subjects were instructed twenty normal healthy elders (8 men and 12 women) and ten chronic stroke patients (4 men and 6 women). They were tested while standing on a force platform under two conditions; LS, no LS were applied in random order. Prior to testing, adhesive surface EMG electrodes were fastened to the skin overlying the right (non-paralytic side in stroke patient) bellies of tibialis anterior (TA) and lateral gastrocnemius (LG) muscles. They were assessed on postural sway and %MVC (Maximum voluntary contraction) of TA and LG. Results: Participants showed that the application of LS brought about a decrease in postural sway as expressed by average sway path and velocity. %MVC of TA and LG were increased. The application of LS to normal and stroke patients decreases postural sway during quite stance. Conclusion: These findings the application of LS to normal and stroke patients improves static balance.

• Science of Emotion and Sensibility
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• v.5 no.4
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• pp.67-75
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• 2002

The purpose of this study is to assess the ability of balance control in virtual moving surround stimulation using head mount display (HMD) device and force platform in patients with brain injury. Fifteen patients with stroke (mean age 54.47 yrs) and fifteen healthy normal persons participated. COP parameters were obtained total path distance, frequency of anterior-posterior and medial-lateral component by FFT analysis, weight-spectrum analysis in the two different conditions; (1) during comfortable standing with opened or closed eyes, (2) during virtual moving surround stimulation delivered using HMD with four different moving pattern. Moving patterns consisted of close-far, superior-inferior lilting (pitch) , right-left tilting (roll) and horizontal rotation (yaw) movement. In all parameters, the test-retest reliability was high. Also, the construct validity of virtual moving surround stimulation was excellent (p＜0.05). A posturographic balance assessment system equiped with virtual moving surround stimulation using HMD is considered clinically useful in evaluation of balance control in patients with brain injury.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.517-521
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• 2016

General industrial robots are difficult to use for precision assembly because they are operated based on position control. Their position accuracy is also usually higher than the assembly clearance (several tens of ${\mu}m$). In previous researches, force control was suggested as a robotic assembly solution. However, this method is difficult to apply in reality because of speed and cost problems. The RCC provides high speed, but applications are limited because the compliance is fixed, and it cannot detect an assembly condition during a task. A variable passive compliance device (VPCD) was developed herein. The VPCD can detect the assembly condition during tasks. This device can provide proper compliance for successful assembly tasks. The pneumatic system and the Stewart platform with an LVDT sensor were applied for measuring the displacement and variable compliance, respectively. The concept design and analysis were conducted to prove the effectiveness of the developed VPCD.