• Journal of Institute of Control, Robotics and Systems
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• v.8 no.10
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• pp.890-897
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• 2002

This paper deals with the reduction of trajectory tracking error by changing the initial postures of a biped robot. Gait of a biped robot depends on the constraints of mechanical kinematics and the initial states including the posture. Also the dynamic walking stability in a biped robot system is analyzed by zero moment point(ZMP) among the stabilization indices. Path trajectory, in which knee joint is bent forward like human's cases, is applied to most cases considered with above conditions. A new initial posture, which is similar to bird's gait, is proposed to decrease trajectory tracking error and it is verified through real experimental results.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.452-460
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• 2005

Based on an introduced optimal trajectory planning method, this paper mainly deals with the accuracy analysis during the function approximation process of the optimal trajectory planning method. The basis functions are composed of Hermit polynomials and Fourier series to improve the approximation accuracy. Since the approximation accuracy is affected by the given orders of each basis function, the accuracy of the optimal solution is examined by changing the combinations of the orders of Hermit polynomials and Fourier series as the approximation basis functions. As a result, it is found that the proper approximation basis functions are the $5^{th}$ order Hermit polynomials and the $7^{th}-10^{th}$ order of Fourier series.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2804-2807
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• 2000

This paper suggests a method of the forward dynamic analysis for the computer simulation on the analysis of the dynamic behavior for biped walking robot. The equations f motion of the system or the simulation are constructed by using the Method of the multibody dynamics which is powerful method for modeling of the complex biped system. For the simplicity of simulation, we consider that the sole of the contacting foot is affected by the reaction forces for tree structure system topology instead of the addition or deletion of the kinematic constraints. The ground reaction forces can be modeled using the simple spring and damper model at the three contacting points on the sole of the foot. For minimizing the errors of numerical integration, the number of equations of motion is minimized by adding the driving constraints or a controller instead of the direct driving torques.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6237-6245
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• 2013

This study examined the effects of backward walking with rhythmic auditory stimulation on the gait and balance of stroke patients. Twenty-one people were divided randomly into three groups; group I(n=7, forward walking), group II(n=7, backward walking), group III(n=7, backward walking by rhythmic auditory stimulation). Each group was trained for 30 minutes 5 times per week for 3 weeks, and was evaluated using a 10m walking test, time up and go test, functional reach test, stride length and step length asymmetry ratio. As a result, the pre- to post-test measures revealed a significant effect in each group on the gait speed, gait symmetry and balance(p<.05). The walking speed, gait symmetry and balance were higher in group II (p<.05) than in group I and it was the highest in group III(p<.05). The stride length was higher in group II and group III(p<.05) than in group I. In conclusion, for stroke patients, backward walking training with rhythmic auditory stimulation is effective on the gait speed, gait symmetry and balance.

• Journal of Korean Society of Disaster and Security
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• v.6 no.1
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• pp.79-86
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• 2013

As car-oriented road policies have been made forward so far, relatively pedestrians' walking conditions are so in poor environments that more than two thousand pedestrians die from car accidents every year. Pedestrians' walking right has been severely invaded like that. Pedestrians' walking right is a right that people are able to walk safely and comfortably in pleasant surroundings as long as they don't threaten the public safety, order maintenance, and welfare. The government has an obligation to provide safe, comfortable, and pleasant environments to pedestrians. Recently interests in pedestrians' safety are increasing, government-driven supports have been made to make safe, pleasant, and healthy walking surroundings. As poor walking condition improvement projects cost high, they should be progressed to accomplish maximal effects using finite finances efficiently, and post feasibility evaluations of the projects should be severely estimated. However site selecting indicators which satisfy with the goal for composing safe working surroundings have not been decided yet, though currently it has a legal basis to specify walking condition improvement sites by the Law for Pedestrians' safety and Comfort Increasement. Therefore this study focuses on suggesting improved ways for selecting sites where pedestrians' safe environment project by reviewing previous research. When project sites are selected, evaluation indicators related to awareness survey of residents and history should be excluded, and disaster safety assessments for walking safety facilities, latent human hazards and natural disasters like a strong wind are proposed besides evaluations on pedestrians' safety and walking environment for matching with the purpose of the project to make safe working surroundings.

• Physical Therapy Korea
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• v.21 no.3
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• pp.80-88
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• 2014

Previous studies have reported that decreased cognitive ability has been consistently associated with significant declines in performance of one or both tasks under a dual-task walking condition. This study examined the relationship between specific cognitive abilities and the dual-task costs (DTCs) of spatio-temporal gait parameters in stroke patients. The spatio-temporal gait parameters were measured among 30 stroke patients while walking with and without a cognitive task (Stroop Word-Color Task) at the study participant's preferred walking speed. Cognitive abilities were measured using Computerized Neuropsychological Testing. Pearson's correlation coefficients (r) were calculated to quantify the associations between the neuropsychological measures and the DTCs in the spatio-temporal gait parameters. Moderate to strong correlations were found between the Auditory Continuous Performance test (ACPT) and the DTCs of the Single Support Time of Non-paretic (r=.37), the Trail Making A (TMA) test and the DTCs of Velocity (r=.71), TMA test and the DTCs of the Step Length of Paretic (r=.37), TMA test and the DTCs of the Step Length Non-paretic (r=.36), the Trail Making B (TMB) test and the DTCs of Velocity (r=.70), the Stroop Word-Color test and the DTCs of Velocity (r=-.40), Visual-span Backward (V-span B) test and the DTCs of Velocity (r=-.41), V-span B test and the DTCs of the Double Support Time of Non-paretic (r=.38), Digit-span Forward test and the DTCs of the Step Time of Non-paretic (r=-.39), and Digit-span Backward test and the DTCs of the Single Support Time of Paretic (r=.36). Especially TMA test and TMB test were found to be more strongly correlated to the DTCs of gait velocity than the other correlations. Understanding these cognitive features will provide guidance for identifying dual- task walking ability.

• Journal of Korean Physical Therapy Science
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• v.26 no.3
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• pp.70-75
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• 2019

Purpose: The purpose of this study was to investigate the changes of static and dynamic balance control ability according to the stability of shoes in elderly woman and female university student. Design: Cross-sectional study. Methods: Six elderly women and seven female university students were recruited for this study. The subject's static and dynamic balance were evaluated while wearing two different types of shoes (comfortable running shoe and masai walking shoe). The BT4 system was used to measure the static (postural sway area and velocity) and dynamic balance (limit of stability on forward, backward and left and right side). The measurement of static and dynamic balance control ability was performed in standing posture wearing comfortable running shoes and masai walking shoes. Results: In the static balance control ability, both female university students and elderly women showed significant increase in postural sway area and velocity when wearing unstable shoes (p<0.05) In addition, in the dynamic balance control ability, both female university students and elderly women showed significant decrease in limit of stability on forward and backward when wearing unstable shoes (p<0.05). Conclusion: In selecting shoes for the elderly, the stability of shoe should be considered for prevention of falls.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.161-169
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• 2008

The purpose of this study was to investigate kinetic variables of the lower extremity during walking on three different stair widths in healthy adults. Ten healthy college-aged adults($23.5{\pm}3.5$) recruited for this study. Each stairs with the same height and length(l8cm and 90cm) under the Korean Constructional Law but three different widths(26cm, 31cm and 36cm) were conducted for this study. One force plate(9286AA, Kistler Co.) was put on third stairs. One-way ANOVA was performed to find the stair width effects during stair walking and the following findings ware obtained. There was significantly decreased in ankle resultant joint moment at Pull-Up phase(p<.05) and, significantly increased in knee extension moment during mid-stance phase as stair width increase(p<.05), but there was no significance in ankle resultant joint moment was found at Forward Continuance Phase in Ascending Stair Walking and There was significantly increased in ankle resultant joint moment as stair width increase during mid-stance phase(p<.05) and no significance in knee and hip resultant moments among the stair width in descending stair walking.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.415-421
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• 2005

Passive RFID tag does not have its own power, so it has very poor computation abilities and it can deliver signals in very short range. From the facts, most RFID Tag security schemes assumed that the backward channel from tags to a reader is safe from eavesdropping. However, eavesdroppers near a tag can overhear message from a tag illegally. In this paper, we propose a method to protect the backward channel from eavesdropping by illegal readers. The proposed scheme can overcome the problems of conventional schemes such as randomized tree walking, which have been proposed to secure tag information in tree-walking algorithm as an anti-collision scheme for RFID tags. We showed the efficiency of our proposed method by using an analytical model, and it is also shown that the proposed method can provide the probability of eavesdropping in some standardized RFID tag system such as EPCglobal, ISO, uCode near to '0'.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.326-335
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• 2019

This study is focusing on teenagers who are needed a correction program called "Gillwe School". This program has a companion who is called a guide and the guide leads them correction program while walking with teenagers. This report has represented 131 semantic units, 7 sub-constituencies and 4components through analysis of 46 cases of the companion participants stories since 2014 and clearly, defined as the final four regions ("Understanding of protection youth", "Positive change of companion's gaze", "Doubts the walking program", "Program's effectiveness and Companion's importance,".) Through a series of studies, I look forward to finding ways to develop programs for the protection of juvenile correctional professionals, such as trarining professional counselors for protection youth, duration and number of correction programs, and expanding the number of participants.