• Journal of Biomedical Engineering Research
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• v.42 no.6
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• pp.295-303
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• 2021

Idiopathic normal-pressure hydrocephalus (INPH) is considered a potentially treatable neurological disorder by shunt surgery and characterized by a triad of symptoms including gait disturbance, cognitive impairment and urinary dysfunction. Although disorders of white matter are generally viewed as the principal pathological features of INPH, analysis of cortical features are important since the destruction of neural tracts could be associated with cortical structural changing. The aim of the study was to determine whether there was any relationship between gait parameter and structural features of cerebral cortex in INPH patients. Gait parameters were measured as follows: step width, toe in/out angle, coefficient of variation (CV) value of stride length, CV value of stride time. After obtaining individual brain MRI of patients with INPH and hemispheric cortical surfaces were automatically extracted from each MR volume, which reconstructed the inner and outer cortical surface. Then, cortical thickness, surface area, and volume were calculated from the cortical surface. As a result, step width was positively correlated with bilateral postcentral gyrus and left precentral gyrus, and toe in/out was positively correlated with left posterior parietal cortex and left insula. Also, the CV value of stride length showed positive correlation in the right superior frontal sulcus, left insula, and the CV value of stride time showed positive correlation in the right superior frontal sulcus. Unique parameter of cerebral cortical changes, as measured using MRI, might underline impairments in distinct gait parameters in patients with INPH.

• The KIPS Transactions:PartA
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• v.12A no.3 s.93
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• pp.215-222
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• 2005

The efficient utilization of cache memories is a key factor in achieving high performance for computing large signal transforms. Nonunit stride access in computation of large DFTs causes cache conflict misses, thereby resulting in poor cache performance. It leads to a severe degradation in overall performance. In this paper, we propose a dynamic data layout approach considering the memory hierarchy system. In our approach, data reorganization is performed between computation stages to reduce the number of cache misses. Also, we develop an efficient search algorithm to determine the optimal tree with the minimum execution time among possible factorization trees considering the size of DFTs and the data access stride. Our approach is applied to compute the fast Fourier Transform (FFT). Experiments were performed on Pentium 4, $Athlon^{TM}$ 64, Alpha 21264, UtraSPARC III. Experiment results show that our FFT achieve performance improvement of up to 3.37 times better than the previous FFT packages.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.371-376
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• 2001

Since continuous media such as video and audio data are displayed within a certain time constraint, their computation and manipulation should be handled under limited condition. Traditional real-time scheduling algorithms cold be directly applicable, because they are not suitable for multimedia scheduling applications which support many clients at the same time. Rate Regulating Proportional Share Scheduling Algorithm based on the stride scheduler is a scheduling algorithm considered the time constraint of the continuous media. The stride schedulers, which are designed to general tasks, guarantee the fairness of resource allocation and predictability. The key concept of RRPSSA is a rate regulator which prevents tasks from receiving more resource than its share in a given period. But this algorithm loses fairness which is a strong point of the stride schedulers, and does not show graceful degradation of performance under overloaded situation. This paper proposes a new modified algorithm, namely Modified Proportional Share Scheduling Algorithm considering the characteristics of multimedia data such as its continuity and time dependency. Proposed scheduling algorithm shows graceful degradation of performance in overloaded situation and it reduces the scheduling violations up to 70% by maintaining the fair resource allocation. The number of context switching is 8% less than RRPSSA and the overall performance is increased.

• Physical Therapy Korea
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• v.19 no.4
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• pp.16-23
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• 2012

This study examined the effects of custom-made foot orthotics on the temporal-spatial gait parameters in children with cerebral palsy. Twenty spastic bilateral cerebral palsy (spastic CP) children (11 boys and 9 girls) participated in this study. GAITRite was used to examine the velocity, cadence, step length differential, step length, stride length, stance time, single support time, double support time, base of support, and toe angle while walking with and without foot orthotics. The differences in temporal-spatial parameters were analyzed using paired t-test. The significance level was set at .05. The velocity, cadence, both step lengths, both stride lengths, both bases of support and right toe angle significantly increased when the children with spastic CP with foot orthotics compared to without foot orthotics (p<.05). The step length differential between the two extremities, left stance time and left single support time, significantly decreased with foot orthotics (p<.05). Right stance time, right single support time, both double support times and left toe angle showed little change (p>.05). This study demonstrated that foot orthotics were beneficial for children with spastic CP as a gait assistance tool.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.77-83
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• 2013

The purpose of this study was to compare kinematic variables and stiffnesses of ankle joints between normal person and transfemoral amputee gait in order to develop or fit prosthetic leg. Twenty subjects (ten normal persons and ten transfemoral amputees) participated in this experiment, and walked three trials at a self-selected pace. The gait motions were captured with Vicon system and variables were calculated with Visual-3D. The velocity, stride length, stride width, cycle time, double limb support time and right swing time of gaits were statistically significant. Because coefficients of variability of normal persons on velocity, double limb support time and swing time were greater than transfemoral amputees, normal persons controlled these gait variables effectively. The stiffnesses of ankle joints were not statistically significant, but patterns of stiffnesses of ankle joints during three rockers were absolutely different. The negative correlations between stiffnesses of ankle joints and cycle time and swing time were presented. These differences suggest that developing and fitting prosthetic leg were demanded. Further studies should develop fitting program and simulator of prosthetic leg.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.69-74
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• 2014

PURPOSE: The aim of this study is to compare the spatio-temporal gait parameters between paretic and non-paretic limb while stepping over the different obstacle's heights in subjects with stroke. METHODS: Nine subjects with stroke were participated in this study. Subjects were asked to step over obstacles with a different height. 8 camera motion analysis system(Motion Analysis Corporation, Santa Rosa, USA) was used to measure spatio-temporal parameters. The two way repeated measurement ANOVA was used to compare spati-temporal gait parameters between paretic and non-paretic limbs while stepping over a different obstacle's height(0cm, 10cm, 20cm). RESULTS: Step width, velocity, single supoort time, and double support time were not different among obstacle's height(p>0.05) but stride length, step length, and cadence were significantly different(p>0.05). In stride length, cadence, and double support time, the interactions between obstacle's heights and limbs were not different(p>0.05) but it was significantly different in velocity, step length, and single support time(p<0.05). Velocity, stride length, cadence, and double support times were not different between paretic limb and non-paretic limb(p>0.05) but step length and single support times were significantly different between paretic limb and non-paretic limb(p<0.05). CONCLUSION: These results show that there are differences with spatio-temporal gait parameters among obstacle's heights and between paretic and non-paretic limb during obstacle crossing in subjects with stroke.

• Physical Therapy Rehabilitation Science
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• v.3 no.1
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• pp.43-48
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• 2014

Objective: The purpose of this study was to examine the influences on gait features during mobile phone use while ramp walking. Design: Cross-sectional study. Methods: Thirty-three healthy adult subjects performed four walking conditions on an outside ramp with a 5 m length, 1.5 m width, and a $5^{\circ}$ angle. All participants were touch screen mobile phone users. Four walking conditions were used: 1) ramp ascent, 2) ramp descent, 3) texting during ramp ascent, and 4) texting during ramp descent. In conditions 3) and 4), subjects texted the words of "Aegukga"-the song of patriotism-while walking. Upon the signal of start, the subjects walked the ramp during texting. Gait parameters were measured at the length of 3 m excluding 1 m of the start and end of the total length. Each situation was repeated three times for each subject, and mean values were calculated. For gait examination, a gait analyzer was used (OptoGait). Results: Subjects ranged in age from 23 to 38 years (mean age, 27.73). Eighty-three percent of subjects in our study had experienced an accident during mobile phone use. Texting on a mobile phone while walking significantly decreased ramp gait, speed, cadence, stride length, step length, and single support (p<0.05) and significantly increased stride time, step time, gait cycle, and double support (p<0.05). There was a significant difference in cadence, step length, stride time, step time, and single support during ramp ascent and descent (p<0.05). Conclusions: Texting on a mobile phone while walking significantly decreased gait quality.

• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.51-63
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• 2004

The purpose of this study was to investigate a three dimensional kinematic variables about the last stride and the release phase of the throwing technique for female javelin throwers. For the motion analysis, Six female javelin throwers were used as subjects. Three-dimensional coordinates were collected using the Kwon3D Motion Analysis Package Version 2.1 Program. Two S-VHS Video Cameras were used to record the locations and orientations of control object and the performances of the subjects at a frequency of 6.0 HZ. After the kinematic variables such as the time, the distance, the velocity, and the angle were analyzed about the last stride and release phase, the followings were achieved; 1. For the effectively javelin throwing, the subjects appeared to do long the approach time in the phasel of landing phase, and short the delivery time in release phase 2. In the release event, the other subjects except for subject A appeared to throwing in the lower condition than the height of themselves. This result showed to slow the projecion velocity. 3. For increase the projection vcelocity of the upper extremity joint in the release event, it appeared to do extend rather the shoulder angle than increase the extension of elbow joint. 4. The body of COG angle showed to gradually increase nearly at the vertical axis in the release event. But the front lean angle of trunk showed a small angle compare to increase of the body of COG angle. Therefore for the effectively momentum transmission of the whole body in the javelin, the front and back lean angle of trunk appeared to do fastly transfer the angle displacement in the arch posture or the crescent condition during the deliverly motion of the release phase.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.5
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• pp.929-943
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• 2020

Various methods are being presented to identify the movements of COVID-19 infected persons and to protect personal privacy at the same time. Among them, 'Exposure Notification' released by Apple and Google follows a decentralized approach using Bluetooth. However, the technology must always turn on Bluetooth for use, which can create a variety of security threats. Thus, in this paper, the security assessment of 'Exposure Notification' was performed by applying 'STRIDE' and 'LINDDUN' among the security threat modeling techniques to derive all possible threats. It also presented a new Dell that derived response measures with security assessment results and improved security based on them.

• 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.