• The Journal of Korean Physical Therapy
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• v.29 no.4
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• pp.164-168
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• 2017

Purpose: Functional electrical stimulation (FES) is a device that activates the sensorimotor cortex through electrodes attached to the surface of the skin. However, it is difficult to expect positive changes if the recipient is not attentive to the motion. To complement the perceived cognitive limitations of FES, we attempted to investigate the changes of sensorimotor cortex activity by simultaneously providing action observation with FES. Methods: Electroencephalogram was measured in 28 healthy volunteers. Relative band power over the sensorimotor cortex was analyzed and compared in three conditions: during rest, during FES alone, during action observation with FES. Results: The results showed significant differences in each relative band power. Relative alpha power and relative beta power were the lowest by application of FES combined with action observation, while the relative gamma power was the highest. Conclusion: These results suggest that combining FES with observation could be more effective than FES alone in neurorehabilitation.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.3
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• pp.171-180
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• 2019

Purpose : The purpose of this study was to investigate the difference in motor cortical excitability during mental practice and action observation in subjects with forward head posture. Methods : This study was performed in two groups, a forward head posture group (n=17) and a normal posture group (n=17). Electroencephalography (EEG) was conducted to investigate cerebral cortex activity, and six electrodes were attached to Fp1, Fp2, C1, C2, C3, and C4 to measure the relative alpha power, relative beta power, relative gamma power, and mu rhythms. The subjects were requested to perform the four different conditions, which were eye opening, eye closing, mental practice, and action observation for 300 seconds. Results : The results showed that the relative alpha waves showed a significant difference between the normal and forward head posture groups in the C1, C2, C3, and C4 regions with the eyes open (p<.05). The relative beta waves also showed a significant difference between the two groups in the Fp1 and Fp2 regions during action observation (p<.05). The relative gamma waves were significantly different between the normal and forward head posture groups in the Fp1 and Fp2 regions during action observation (p<.05) in C1, C2, and C3 with eyes closed (p<.05) and in C1, C2, C3, and C4 with eyes open (p<.05). Conclusion : The results of this study showed that EEG change in the forward head posture group was different from that in the normal control group in action observation rather than in mental practice. Therefore, we are expected to provide a neurophysiological basis for applying action observation to motor skill learning during exercise for correcting forward head posture.

• The Journal of Korean Physical Therapy
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• v.29 no.1
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• pp.27-32
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• 2017

Purpose: Recent electrophysiological studies have shown that the sensorymotor cortex is activated during both actual action excuted by themselves and observation of action performed by other persons. Observation of action based on mirror neuron system can be used as a cognitive intervention to promote motor learning. The purpose of this study was to investigate the brain activity changes during action observation and action execution using EEG. Methods: Thirty healthy volunteers participated and were requested to perform hand action and to observe the video of hand action performed by another person. The EEG activity was evaluated by a method which segregated the time-locked for each condition. To compare the differences between action observation and execution, the Mu suppression and the relative band power were analysed. Results: The results showed significant mu suppression during the action observation and execution, but the differences between the two conditions were not observed. The relative band power showed a significant difference during the action observation and execution, but there were no differences between the two conditions. Conclusion: These results indicate that action execution and observation involve overlapping neural networks in the sensorymotor cortical areas, proposing positive changes on neurophysiology. We are expected to provide information related to the intervention of cognitive rehabilitation.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.110-117
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• 2022

This paper describes a localization algorithm utilizing relative observations for multiple autonomous underwater vehicles (Multiple-AUVs). In order to maximize the efficiency of operation and mission accomplishment and to prevent problems such as collision and interference, the locations and directions of Multiple-AUVs must be precisely estimated. To estimate the locations and directions, we designed a localization algorithm utilizing relative observations and verified it with simulations based on sensor data sets acquired through real sea experiments. Also, an optimal combination of relative observation information for efficient localization is figured out through combining various relative observations. The proposed method shows improved localization results compared to those only using the navigation algorithm. The performance of localization is improved up to 58% depending on the combination of relative observations.

• Atmosphere
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• v.24 no.1
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• pp.69-76
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• 2014

Urbanization affects the local thermal environment due to the large scale land use changes. To investigate the weather environment change of large scale urban redevelopment, 9 surface temperature and humidity observations were accomplished at Eunpyeong new town area. The observation period is from March 2007 to February 2010. In the center of development area, the air temperature has increased and relative humidity has decreased, by the changes of the land cover and building construction. In the area where the green zone is maintained, air temperature and relative humidity were not changed significantly. The air temperature and relative humidity for the other development observation stations is decreased and increased, respectively. The relative temperature difference between study area and a neighboring rural location was increased during observation periods. The difference is the highest during winter. The urban-rural minimum temperature difference was increased at development area, which means that urbanization affects increasing of minimum temperature in study area.

• The Journal of Korean Physical Therapy
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• v.28 no.6
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• pp.398-407
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• 2016

Purpose: The purpose of this study was to examine the changes in electroencephalogram (EEG) coherence and brain wave activity for first-person perspective action observation (1AO) and third-person perspective action observation (3AO) of healthy subjects. Methods: Thirty healthy subjects participated in this study. EEG was simultaneously recorded during the Relax period, the 1AO, and the 3AO, with event-related desynchronization (ERD) and coherence connectivity process calculations for brain wave (alpha, beta and mu) rhythms in relation to the baseline. Results: Participants showed increased coherence in beta wave activity in the frontal and central areas (p<0.05), during the 1AO using right-hand activity. Conversely, the coherence of the alpha wave decreased statistically significantly decreased in the frontocentral and parieto-occipital networks during the observation of the 1AO and the 3AO. The ERD values were larger than 40% for both central regions but were slightly higher for the C4 central region. The high relative power of the alpha wave during 1AO and 3AO was statistically significantly decreased in the frontal, central, parietal, and occipital regions. However, the relative power of the beta wave during 1AO and 3AO was statistically significantly increased in the parietal and occipital regions. Especially during 1AO, the relative power of the beta wave in the C3 area was statistically significantly increased (p<0.05). Conclusion: These findings suggest that 1AO and 3AO action observations are relevant to modifications of specific brain wave coherence and ERD values. EEG cortical activity during action observation may contribute to neural reorganization and to adaptive neuroplasticity in clinical intervention.

• Journal of Korean Physical Therapy Science
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• v.26 no.3
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• pp.1-7
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• 2019

Purpose: The purpose of this study was to investigate the effects of the Otago exercise combined with action observation training on changes of the brain activity of the elderly. Design: Randomized controlled trial. Methods: Thirty elderly women in the experiment were included. Participants were randomly assigned to the Otago combined with action observation training group, the Otago exercise group, and the control group (10 in each group). The Otago combined with action observation training group and the Otago exercise group performed the strength and balance exercises of the Otago exercise program for 50 minutes three times a week for 12 weeks. The Otago combined with action observation training group underwent additional action observation training for the Otago movement for 20 minutes three times a week. No intervention was performed in the control group. PolyG-1 (LAXTHA Inc., Daejeon, Korea) was used to measure the changes in the brain activity following intervention. One-way analysis of variance was used to compare the effects among the groups and a post-hoc test was performed. Results: The relative mu rhythms in the F3, C3, and C4 regions were significantly increased in the Otago combined with action observation training group. Relative beta wave activity in the Fp1, F3, F3, and C3 regions was significantly increased in the Otago combined with action observation training group (p<0.05). Conclusion: The results indicated that the Otago exercise combined with action observation training was effective for promoting the brain activity of the elderly.

• Atmosphere
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• v.30 no.2
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• pp.169-181
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• 2020

We conducted a study on the impact of observation station density; this was done in order to enable the accurate estimation of spatial meteorological variables. The purpose of this study is to help operate an efficient observation network by examining distributions of temperature, relative humidity, and wind speed in a test area of a three-dimensional meteorological observation project in the Yeongdong region in 2019. For our analysis, we grouped the observation stations as follows: 41 stations (for Step 4), 34 stations (for Step 3), 17 stations (for Step 2), and 10 stations (for Step 1). Grid values were interpolated using the kriging method. We compared the spatial accuracy of the estimated meteorological grid by using station density. The effect of increased observation network density varied and was dependent on meteorological variables and weather conditions. The temperature is sufficient for the current weather observation network (featuring an average distance about 9.30 km between stations), and the relative humidity is sufficient when the average distance between stations is about 5.04 km. However, it is recommended that all observation networks, with an average distance of approximately 4.59 km between stations, be utilized for monitoring wind speed. In addition, this also enables the operation of an effective observation network through the classification of outliers.

• Communications for Statistical Applications and Methods
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• v.6 no.3
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• pp.667-676
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• 1999

We investigate the effects of omission of initial observations in each individuals in the panel data regression model when the disturbances follow a serially correlated one way error components. We show that the first transformed observation can have a relative large hat matrix diagonal component and a large influence on parameter estimates when the correlation coefficient is large in absolute value.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.1
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• pp.15-21
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• 2011

Purpose : This study aims to examine the effects of action observation of ski simulation on electroencephalogram (EEG). Methods : Thirty healthy subjects were randomly divided into three groups: 10 participants in an AM (actual movement) group; 10 participants in an OM (observation) group; and 10 participants in a CM (control movement) group. The EEG was measured to examine changes in EEG between action observation and actually movement at 8 areas of the scalp for one minute before, during and after action observation. Results : Relative alpha power showed statistically significant differences among groups in Cz and C4 and there were interactions among groups in the Oz area. Relative beta power showed no statistical significance among groups and in particular, there were interactions among groups in the Oz area. Conclusion : These findings show that action observation affected brain activation as in actual movement. Thus it can be expected that when movement through the brain activation is applied to patients in bed rest or those who cannot perform actually movement, it can be utilized as physiotherapy.