• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.580-599
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• 2021

Software-Defined Networking (SDN) has three key features: separation of control and forwarding, centralized control, and network programmability. While improving network management flexibility, SDN has many security issues. This paper systemizes the security threats of SDN using spoofing, tampering, repudiation, information disclosure, denial of service, and elevation of privilege (STRIDE) model to understand the current security status of SDN. First, we introduce the network architecture and data flow of SDN. Second, we analyze security threats of the six types given in the STRIDE model, aiming to reveal the vulnerability mechanisms and assess the attack surface. Then, we briefly describe the corresponding defense technologies. Finally, we summarize the work of this paper and discuss the trends of SDN security research.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.49-58
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• 2008

The purpose of this study was to identify effects of walking speed and a cognitive task during treadmill walking on gait variability. Experiments consisted of 5 different walking speeds(80%, 90%, 100%, 110% and 120% of preferred walking speed) with/without a cognitive task. 3D motion analysis system was used to measure subject's kinematic data. Temporal/spatial variables were selected for this study; stride time, stance time, swing time, step time, double support time, stride length, step length and step width. Two parameters were used to compare stride-to-stride variability with/without cognitive task. One is the coefficient of variance which is used to describe the amount of variability. The other is the detrended fluctuation analysis which is used to infer self-similarity from fluctuation of aspects. Results showed that cognitive task may influence stride-to-stride variability during treadmill walking. Further study is necessary to clarify this result.

• Journal of Korean Physical Therapy Science
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• v.12 no.3
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• pp.47-58
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• 2005

The purpose of this study is to estimate how much the motility of affected and unaffected lower limb respectively would have effects on their ambulation through comparing the difference between their affected and unaffected lower limb and studying the correlation between such difference and their ambulation. In addition, the study also intends to find out remedial measures suitable for improving their ambulation with relevant physical treatment. To do this, a quantitative electromyogram(QEMG) test was done to both quadriceps and hamstring of affected and unaffected lower limb so as to yield IP values. Based on such IP values, RMS(root mean square) values as the total sum of IP values were found with QEMG analysis system (made by Medelec Co.) and then the ambulation depending on the difference in muscular strength were analyzed by ink-foot print method as well as the corresponding statistics were processed by T-test through SPSS. The effect of differences in muscular strength of quadriceps in affected and unaffected limb of hemiplegic patients on their ambulation was also different in each element of ambulation. However, there was not any statistically significant difference (p>.05). The differences in muscular strength of hamstring in unaffected limbs of hemiplegic patients only affect stride length. It was statistically significant. The effect of difference in muscular strength of the hamstring in affected limb of hemiplegic patients on their ambulation was very different between strong and weak group in terms of walking velocity, step per minute, stride and step length, showing statistically significant difference(p<.05). Although there was a difference in the step length of the affected limb, it was not statistically significant(p>.05). For the unaffected hamstring, there were significant differences of stride length between in unaffected limb and in affected limb. For the affected hamstring, there were also significant differences in walking velocity, step per minute, stride and step length. Besides, it was found that the difference of the muscular strength between strong and weak group was at the highest. Thus, the effect of difference in muscular strength on ambulatory factors such as walking velocity, step per minute, stride and step length did not show any statistical significance but differences in affected and unaffected quadriceps. However, it was found that both the difference of stride in unaffected hamstring and the difference of all ambulatory factors except from step length with affected limb had effects on ambulation depending upon muscular strength.

• Korean Journal of Remote Sensing
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• v.39 no.3
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• pp.269-282
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• 2023

The purpose of this study was to construct land cover maps using a deep learning model and to select the optimal deep learning model for land cover classification by adjusting the dataset such as input image size and Stride application. Two types of deep learning models, the U-net model and the DeeplabV3+ model with an Encoder-Decoder network, were utilized. Also, the combination of the two deep learning models, which is an Ensemble model, was used in this study. The dataset utilized RapidEye satellite images as input images and the label images used Raster images based on the six categories of the land use of Intergovernmental Panel on Climate Change as true value. This study focused on the problem of the quality improvement of the dataset to enhance the accuracy of deep learning model and constructed twelve land cover maps using the combination of three deep learning models (U-net, DeeplabV3+, and Ensemble), two input image sizes (64 × 64 pixel and 256 × 256 pixel), and two Stride application rates (50% and 100%). The evaluation of the accuracy of the label images and the deep learning-based land cover maps showed that the U-net and DeeplabV3+ models had high accuracy, with overall accuracy values of approximately 87.9% and 89.8%, and kappa coefficients of over 72%. In addition, applying the Ensemble and Stride to the deep learning models resulted in a maximum increase of approximately 3% in accuracy and an improvement in the issue of boundary inconsistency, which is a problem associated with Semantic Segmentation based deep learning models.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.876-881
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• 2008

When biped robots speed up to run and reduce speed to walk after running, it needs stable speed translation. This paper proposed simple speed translation using the modified LIPM (Linear Inverted Pendulum Mode). We can change stride and period time of a biped robot in some bounded sets with this propose algorithm. This method is simple and effective in simulation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.331-332
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• 2022

본 논문에서는 3축 가속도와 3축 각속도 센서로 구성된 관성 측정 장치(IMU)와 압력센서가 내장되어있는 스마트 인솔을 착용하여 얻어진 보행 데이터를 통해 보폭을 추정하는 방법을 제안한다. 먼저 압력센서를 활용하여 한 걸음 주기로 나눈 뒤 나누어진 가속도와 각속도 센서 데이터를 LSTM과 Attention 계층을 결합한 딥러닝 모델에 학습하여 보폭 추정을 시행하였다. LSTM-Attention 모델은 기존 LSTM 모델보다 약 1.14%의 성능 향상을 보였다.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.139-144
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• 2013

Various types of disease in the nervous and musculoskeletal system can change gait, and the gait analysis is very important in determining the progression of the disease. Most methods of analyzing gait are subject to high-priced equipment and spatial restrictions. This study used smart phone images and the walking track analysis program to make a comparative analysis with the existing gait analysis on the basis of the stride length measurements and the changes in the knee joint angle for walking. The test necessary to analyze gait was conducted in seven healthy men, and data about the angle of right and left knee joints and stride length were used to analyze gait. The gait analysis in this study obtained the similar results to the existing ones. The use of the methods suggested in this study will enable gait analysis to be made without high-priced equipment and spatial restrictions.

• Journal of Korean Physical Therapy Science
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• v.18 no.2
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• pp.17-28
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• 2011

Purpose: The aim of this study was to ascertain the effects of the lower extremity muscle strengthening exercise on balance and ambulation of children with cerebral palsy. Methods: 10 subjects who participated in this research undertook the 12-week the lower extremity muscle strengthening exercise program, which consisted of a series of mat exercises and sling exercises. The statistical significances were examined by using Wilcoxon signed-rank test, a non-parametric test, for evaluating the improvement of balance and ambulation of the subjects. In order to evaluate the correlation among the variables, Pearson's correlation coefficients were also calculated. In all statistical analyses the significance level was selected as ${\alpha}$=0.05. Results: Berg balance scale(BBS) was significantly increased after the intervention(p<.05). Percentage weight bearing(PWB) was decreased after the intervention, but there was no significant difference. Time up and go test(TUG) value was significantly decreased(p<.05). Gait velocities was increased after the intervention, but there was no significance. Stride length, step lengths of the affected side and the sound side were significantly increased after the intervention(p<.05). In the correlation analyses of the measures before the intervention, TUG had significant negative correlation to BBS and gait velocity(p<.05). Stride length, step lengths of the sound side and the affected side had significant positive correlation between themselves(p<.01). In the correlation analyses of the measures after the intervention, TUG had significant negative correlation to BBS and gait velocity(p<.05). BBS revealed significant positive correlations to stride length, step lengths of the sound side and the affected side(p<.05). Stride length, step lengths of the sound side and the affected side had significant positive correlation between themselves(p<.01). Conclusion: Based upon the outcomes as above, it is likely that the muscle strength exercises have substantial effects on balance and ambulation of children with cerebral palsy. Thus various lower extremity muscle strengthening exercise programs are required to be studied and developed in order to contribute to functional improvements of children with cerebral palsy.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.2
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• pp.93-102
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• 2016

PURPOSE: The purpose of this study is to evaluate the functional effects of action observation plus functional electrical stimulation (FES) treatment on the weight distribution indexes (heel and toe; right and left), stability indexes, gait velocities, and stride lengths of stroke patients. METHODS: The subjects, who were all more than six months post stroke, were randomly divided into two groups of ten each: an experimental group and a control group. TETRAX (Tetrax Interactive Balance System) and GAITRite (GAITRite$^{TM}$ computerized gait analysis system) were measured at baseline, six weeks after treatment. Participants in both the groups received functional electrical stimulation treatment, but the experimental group was provided with additional action observation. Independent t-tests were used to compare the differences between the groups, and repeated measured two-way ANOVA was used to compare the interaction between the groups. RESULTS: The result of the interactions between the groups and the periods showed significant increases in the weight distribution indexes (heel and toe; right and left), stability indexes, gait velocities and stride lengths (p<0.05). However, a comparison between the groups showed no significance in the weight distribution indexes (heel and toe), stability indexes, and stride lengths (p>0.05). CONCLUSION: Action observation plus functional electrical stimulation treatment should be considered as a therapeutic method for physical therapy for stroke patients to improve the weight distribution indexes, stability indexes, gait velocities, and stride lengths.

• Journal of Korean Physical Therapy Science
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• v.12 no.4
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• pp.69-77
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• 2005

The purpose of this study is to estimate how much the motility of affected and unaffected lower limb respectively would have effects on their ambulation through comparing the difference between their affected and unaffected lower limb and studying the correlation between such difference and their ambulation. In addition, the study also intends to find out remedial measures suitable for improving their ambulation with relevant physical treatment. To do this, a quantitative electromyogram(QEMG) test was done to hamstring of affected and unaffected lower limb so as to yield IP values. Based on such IP values, RMS(root mean square) values as the total sum of IP values were found with QEMG analysis system (made by Medelec Co.) and then the ambulation depending on the difference in muscular strength were analyzed by ink-foot print method as well as the corresponding statistics were processed by T-test through SPSS. The differences in muscular strength of hamstring in unaffected limbs of hemiplegic patients only affect stride length. It was statistically significant. The effect of difference in muscular strength of the hamstring in affected limb of hemiplegic patients on their ambulation was very different between strong and weak group in terms of walking velocity, step per minute, stride and step length, showing statistically significant difference(p<.05). Although there was a difference in the step length of the affected limb, it was not statistically significant(p>.05). For the unaffected hamstring, there were significant differences of stride length between in unaffected limb and in affected limb. For the affected hamstring, there were also significant differences in walking velocity, step per minute, stride and step length. Besides, it was found that the difference of the muscular strength between strong and weak group was at the highest.