• Physical Therapy Korea
• /
• v.4 no.3
• /
• pp.34-44
• /
• 1997

The purpose of this study was to compare the balance ability at different foot angle with KAT 2000 (Breg, Inc., Vista, CA. 1994). Forty-nine (male 24, female 25) normal subjects participated in this study. All subjects were assessed under two conditions. One was eye-opened condition and the other one was eye-closed one in 3 psi surface condition. All subjects were tested at different foot angle that were toe-in $25^{\circ}$, $45^{\circ}$, toe-out $25^{\circ}$ and $45^{\circ}$. The subject attempted to keep the platform as stable as possible with eyes closed and with eyes opened for every 20 seconds. The starting position was that subject crossed their arms across chest and flexed knees slightly. The results of each test were showed by a score on screen, which meant balance index. The se collected data were analyzed by using oneway ANOVA, Scheffe test, and t-test. The results of this study were as follows: 1. When the foot angle were changed, balance index was the lowest in toes-out $25^{\circ}$ condition and greatest with toes-in $45^{\circ}$ with eyes opened and with eyes closed. There were statistically significant difference with eyes opened and with eyes closed (p<0.05). 2. There was statistically significant difference in balance index according to visual condition and the balance index tested with eyes closed was higher than with eyes closed(p<0.05). 3. There was statistically significant difference in balance index by gender(p<0.05).

• Journal of the Korean Society for Railway
• /
• v.11 no.2
• /
• pp.126-138
• /
• 2008

This paper proposes the preservation method that can effectively process short messages at mobilePOST SMSC(Short Message Service Center) platform on CDMA(Code Division Multiple Access). There are three techniques for the preservation method. First one is shared memory technique where several processes within the system share same memory to process transmission of short messages with maximum performance. Second one is to back-up messages in shared memory to the file system to prevent lost during system initialization or other unstable period. Third technique is that when transmission of short message was completed, finished message is moved from the shared memory to relational database for accounting purposes.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.22 no.1
• /
• pp.69-74
• /
• 2012

In this research equations of motion of a Wheeled Inverted Pendulum (WIP) which is running on the inclined road and changing its center of gravity. Difference between a conventional cart inverted pendulum and the WIP is also considered. The WIP has small planar size so that it has been used as a mobile platform for several applications which require slender frame in order to travel on the narrow road. The WIP has almost the same unstable properties as conventional inverted pendulums have. There needs an aggressive control scheme for the WIP not to fall down. In order to design a high performance control scheme, equations of motion of the WIP, which is running under various environment and operating conditions, should be derived and considering its properties is necessary.

• International Journal of Advanced Culture Technology
• /
• v.4 no.4
• /
• pp.81-86
• /
• 2016

In this paper, we propose a simple and effective vision-based tracking controller design for autonomous object tracking using multicopter. The multicopter based automatic tracking system usually unstable when the object moved so the tracking process can't define the object position location exactly that means when the object moves, the system can't track object suddenly along to the direction of objects movement. The system will always looking for the object from the first point or its home position. In this paper, PID control used to improve the stability of tracking system, so that the result object tracking became more stable than before, it can be seen from error of tracking. A computer vision and control strategy is applied to detect a diverse set of moving objects on Raspberry Pi based platform and Software defined PID controller design to control Yaw, Throttle, Pitch of the multicopter in real time. Finally based series of experiment results and concluded that the PID control make the tracking system become more stable in real time.

• Nuclear Engineering and Technology
• /
• v.53 no.4
• /
• pp.1088-1099
• /
• 2021

Time-frequency analysis technique is an effective analysis tool for non-stationary processes. In the field of reactor neutron noise, the time-frequency analysis method has not been thoroughly researched and widely used. This work has studied the time-frequency analysis of the reactor neutron noise experimental signals under bubble disturbance and control rod vibration. First, an experimental platform was established, and it could be employed to reactor neutron noise experiment and data acquisition. Secondly, two types of reactor neutron noise experiments were performed, and valid experimental data was obtained. Finally, time-frequency analysis was conducted on the experimental data, and effective analysis results were obtained in the low-frequency part. Through this work, it can be concluded that the time-frequency analysis technique can effectively investigate the core dynamics behavior and deepen the identification of the unstable core process.

• Journal of Korean Physical Therapy Science
• /
• v.29 no.2
• /
• pp.20-27
• /
• 2022

Background: The purpose of the present study was to determine whether balance training combined with light touch improves the postural sway and gait speed in stroke patients. Design: Randomized Controlled Trial Study Methods: The current study included 40 stroke patients, who were randomly divided into two groups: the balance training with light touch (LT) group (n=20) and the balance training with heavy touch (HT) group (n=20). Both groups performed balance training on a stable and unstable ground. Additionally, the LT group provided light touch stimulation, and the HT group provided heavy touch stimulation. All the participants underwent 20 sessions of STS training (thirty minutes, five days per week for four weeks). In this study, postural sway was measured using a force platform, and walking speed was measured using a 10 meter walk test. Results: The improvements in postural sway and gait speed were observed to be significantly greater in the LT group, compared to the HT group (p<0.05). Conclusion: The results of the current study imply that balance training combined with light touch is a beneficial and effective therapeutic modality that can be employed to improve the postural sway and gait speed in stroke patients.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.17-25
• /
• 2007

The purpose of the study is to give basic data for the improvement of the skill and to show an exemplary position for squash club members or trainers thru a comparative analysis on the kinematics and kinetics variables on the forehand drive motion in playing squash. The objects of the research are divided into two sections, skilled group(n=8) and unskilled group(n=8). The skilled group is composed of professional players currently working and unskilled group is career of six month, both of lives in B city. In this research, to gather the data 3D motion analysis and test result analysis using force platform was used. The variables are duration, position, segment velocity, segment acceleration and etc. in using force platform. The results are as follows: 1. The duration per phase of the skilled is 0.18sec P1(DS) while that of unskilled is 0.32sec. in P2(FT), the duration of the skilled is 0.29sec, that of unskilled is 0.34sec. Average of the duration of the skilled is 0.48sec, while the unskilled, 0.66sec. 2. Regarding positional movements per event, the unskilled has a relatively higher position in center of gravity, shoulder joint, elbow joint compared with that of the skilled. Generally speaking, positions of the unskilled is higher than the skilled. 3. In segment velocity per event, R-shank, R-upper arm, R-forearm and racket. The skilled is faster than the unskilled. we found a big dig difference in shank. 4. In acceleration per event, there was a big difference in upper-arm and fore-arm of the impact. 5. The skilled group on the force platform shows relatively stable and regular changes while the unskilled shows unstable from the touch down to initial 20% the force value of central support period after the impact moment decreases rapidly and the center of gravity is not moved well. 6. The maximum force value of the skilled is 1019.7N. it is found 19.86% of the total duration. That of the unskilled is 639.2N, it is found 20.67% of total duration.

• Journal of Biomedical Engineering Research
• /
• v.28 no.5
• /
• pp.628-635
• /
• 2007

We studied the effect of vibratory stimulations of different leg muscles, tibialis anterior(TA) and triceps surae(TS), and plantar zones in ten healthy subjects during 1) quiet standing, 2) forward lean of body, 3) backward lean of body, 4) right lean of body, and 5) left lean of body. The experiments were performed on the force platform. The effect of vibration were measured by monitoring the area of COP(Center of pressure) sway. The subjects wore a vibratory stimulation system on foot and ankles and were given the instruction not to resist against the applied perturbations. The results show that all vibratory stimulations to lower limb muscles and plantar zones reduced the COP sway area. This reduction of the COP sway area occurred also in partial vibratory stimulations during quiet standing. In forward lean of body, vibratory stimulations to TA reduced the COP sway area. During backward lean of body, vibratory stimulations to TS reduced the COP sway area. When the subject was tilted right, vibratory stimulations to left plantar zone reduced the COP sway area. During left lean of body, vibratory stimulations to right plantar zone reduced the COP sway area. Thus, the influence of vibratory stimulations to leg muscle and plantar zones differed significantly depending on the lean of body. We suggest that the vibration stimuli from leg muscles and plantar zones could be selectively used to help maintaining postural balance stable.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.1
• /
• pp.145-151
• /
• 2017

In this paper, we propose the design and implementation of the system that is predicting the failure of ballast water treatment system by analysing its sensor datum and is reserving the most effective service center for sellecting the repair location on the way to the destination port. These data are collected in real time during draining or filling up the sea water from/to the ship, and it is essential to preliminarily repair the equipment showing unstable characteristics by analyzing the normal and abnormal data characteristics. We proposed a software platform for predicting and repairing faults by selecting the most efficient repair center based on this e-Navigation while the vessel is navigating to the next destination port. This system, as announced by the IMO Convention for the Prevention of Marine Pollution in 2017, provides a stable economic impact from stable cargo operation and stable out/in from/to port and marine ecosystem.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7941-7948
• /
• 2015

Rolling noises during train operation are caused by vibration excited from irregularities of surface roughness between wheel and rail. Therefore, a proper measurement and analysis techniques of acoustic roughness between wheel and rail surface are required for transmission, prediction, and analysis of the train rolling noise. However, since current measuring devices and methods use trolley-based manual handling devices, the measurements induce unstable measuring speed and vibrational interface that increases errors and disturbances. In this paper, a new automatic rail surface exploring platform with a speed controller has been developed for improving measurement accuracy and reducing inconsistency of measurements. In addition, we propose a data integration method of the rail surface roughness with multiple homogeneous displacement sensors and verified the accuracy of the integrated data through standard test-bed railway track investigation.