• The Journal of Korean Physical Therapy
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• 제23권6호
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• pp.49-53
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• 2011

Purpose: The purpose of this study is to investigate whether dual-hemisphere transcranial direct current stimulation (tDCS) could induce more cortical activity, compared to single-hemisphere, using functional MRI (fMRI). Methods: One right-handed healthy subject was recruited. Three phases of dual-hemisphere tDCS (i.e. anodal tDCS over the left-dominant primary sensoriomotor cortex (SM1) and cathodal tDCS over the right-non dominant SM(1) were consecutively delivered on to a subject, during fMRI scanning. The voxel count and the intensity index in the averaged cortical map were analyzed among the three tDCS phases. Results: Our result showed that cortical activation was observed on all the three phases of the dual-hemisphere tDCS. Voxel count and intensity index were as following; 912 and 4.07 in the first phase, 1102 and 3.90 in the second phase, 1031 and 3.80 in the third phase. Conclusion: This study demonstrated that application of the dual-hemisphere tDCS could induce cortical activity and maintain to recruit cortical neurons. Our findings suggested that application of dual-hemisphere tDCS could produce efficiency of the ongoing tDCS effect to facilitate cortical excitability.

• The Journal of Korean Physical Therapy
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• 제23권2호
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• pp.31-36
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• 2011

Purpose: We investigated the effects of physical practice, mental practice, and cross education using serial reaction time (SRT) in the non-dominant left arm of right-handed individuals. Methods: Subjects were divided into three groups; physical practice (n=8), mental practice (n=8) and controls (n=8). They did, respectively, physical training or mental training, or had no intervention for three weeks. Super lab 4.0 displayed four symbols on the monitor and subjects were asked to push the matching button. Reaction time was assessed pre- and post-intervention. Results: Reaction time was significantly lower after physical practice (p<0.05), but mental practice did not significantly lower reaction time? in the left hand. Also, reaction time was not significantly lower after physical practice or mental practice in the right hand. Conclusion: Physical practice can improve motor learning, but mental practice is not sufficient. Also, neither physical practice nor mental practice is sufficient for cross education from the nondominant to the dominant arm.

• ETRI Journal
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• 제43권6호
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• pp.957-965
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• 2021

A miniaturized wideband band-pass filter with a 3-dB fractional bandwidth of 109.3% (1.53 GHz to 5.22 GHz), high out-of-band attenuation greater than 25 dB, and wide upper stopband up to 14 GHz is proposed. The design consists of a dual-composite right/left handed resonator, embedded open-circuited stub, and a pair of quarter-wavelength short-circuited stubs. These elements are coupled in the near distance to form a miniature filter with a compact occupied area of 0.21 λ_g×0.19 λ_g (≈ 0.013 cm²). The optimized filter has multitransmission poles in the passband, substantially improving the return loss and insertion loss characteristics. The behavior of the passband and stopband is verified against the results of a lumped element model and matrix analysis with a full-wave moment-based analysis and actual measurements. The results of this verification and a comparison with the performance of filters in other references indicate that the proposed filter is very efficient and applicable to compact microwave systems.

• The Journal of Korean Physical Therapy
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• 제31권3호
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• pp.157-160
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• 2019

Purpose: We compared the activation pattern of the mirror neurons (MN) between two types of hand movement according to action observation using functional MRI. Methods: Twelve right-handed healthy subjects (5 male and 7 female, mean age $21.92{\pm}2.02years$) participated in the experiment. During fMRI scanning, subjects underwent two different stimuli on the screen: 1) video clips showing repeated grasping and releasing of the ball via simple hand movement (SHM), and (2) video clips showing an actor performing a Purdue Pegboard test via complex hand movement (CHM). paired t-test in statistical parametric mapping (SPM) was used to compare the activation differences between the two types of hand movement. Results: CHM as compared with the SHM produced a higher blood oxygen level dependent (BOLD) signal response in the right superior frontal gyrus, left inferior and superior parietal lobules, and lingual gyrus. However, no greater BOLD signal response was found by SHM compared with CHM (FWE corrected, p<0.05). Conclusion: Our findings provided that the activation patterns for observation of SHM and CHM are different. CHM also elicited boarder or stronger activations in the brain, including inferior parietal lobule called the MN region.

• 한국운동역학회지
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• 제32권4호
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• pp.121-127
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• 2022

Objective: The purpose of this study was to investigate potential effects of transcranial direct current stimulation (tDCS) on bimanual force control capabilities in healthy young adults. Method: Eighteen right-handed healthy young adults (10 females and 8 males; age: 23.55 ± 3.56 yrs) participated in this crossover design study. All participants were randomly allocated to both active-tDCS and sham-tDCS conditions, respectively. While receiving 20 min of active- or sham-tDCS interventions, all participants performed bimanual isometric force control tasks at four submaximal targeted force levels (i.e., 5%, 10%, 15, and 20% of maximal voluntary contraction: MVC). To compare bimanual force control capabilities including force accuracy, variability, and regularity between active-tDCS and sham-tDCS conditions, we conducted two-way repeated measures ANOVAs (2 × 4; tDCS condition × Force levels). Results: We found no significant difference in baseline MVC between active-tDCS and sham-tDCS conditions. Moreover, our findings revealed that providing bilateral tDCS including anodal tDCS on left primary motor cortex (M1) and cathodal on right M1 while conducting bimanual force control trials significantly decreased force variability and regularity at 5%MVC. Conclusion: These findings suggest that providing bilateral tDCS on M1 areas may improve bimanual force control capabilities at a relatively low targeted force level.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.331-337
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• 2015

A novel fully-printed microstrip antenna with negative first resonance and dual polarization is proposed. The radiator is printed on the 1-layer substrate instead of multilayers. The -1st resonance results from a composite right- and left-handed(CRLH) structure that has a circumferentially interlocked gap capacitively coupling a patch with a shorted-ring. This compact antenna is provided with a dual-polarization capability by creating two orthogonal linear polarizations in one body with coaxial feeds. The design is carried out by doing full-wave EM field simulation which is compared with the measurement of the fabricated antenna prototype. The measured results give the gain of 5 dBi and the efficiency of 78% at the -1st resonance mode as the center frequency of a downlink channel of the bandwidth over 20 MHz with 29 dB polarization isolation for mobile communication.

• 전기학회논문지
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• 제60권12호
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• pp.2299-2304
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• 2011

In this paper, we propose the methodology to make the bandpass filters for the Smart Grid IED(Intelligent Electronic Device) smaller than the conventional bandpass filters. The size-reduction of the filters and the filter performances are indebted to devising small CRLH(composite right- and left-handed) resonators and coupling them as the metamaterial structures. The design methodology is validated by the equivalent circuit to be compared with the reliable full-wave EM simulation, and the proposed metamaterial filter outperforms the standard parallel-edge coupled filter with respect to the miniaturization and frequency response.

• Annals of Clinical Neurophysiology
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• 제13권1호
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• pp.38-43
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• 2011

Background: In the brain, the dominant primary motor cortex (M1) has a greater hand representation area, shows more profuse horizontal connections, and shows a greater reduction in intracortical inhibition after hand exercise than does the non-dominant M1, suggesting a hemispheric asymmetry in M1 plasticity. Methods: We performed a transcranial magnetic stimulation (TMS) study to investigate the hemispheric asymmetry of paired associative stimulation (PAS)-induced M1 plasticity in 9 right-handed volunteers. Motor evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) muscles of both hands, and MEP recruitment curves were measured at different stimulation intensities, before and after PAS. Results: MEP recruitment curves were significantly enhanced in the dominant, but not the non-dominant M1. Conclusions: These results demonstrate that the dominant M1 has greater PAS-induced plasticity than does the non-dominant M1. This provides neurophysiological evidence for the asymmetrical performance of motor tasks related to handedness.

• Journal of electromagnetic engineering and science
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• 제12권4호
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• pp.280-286
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• 2012

The conventionally classified waves are reclassified in this paper, including the waves associated with metamaterial (MTM) transmission lines. Various types of guided waves in periodic structures are analyzed for 1D Composite Right/Left Handed (CRLH) transmission lines (TL). In addition, dispersion diagrams for 1D CRLH, RH, and LH TLs are presented in terms of radiation conditions. We have refined the design equations of the conventional 1D CRLH TL and proposed a condition to realize the desired phase shift and its slope per unit cell. This condition has been applied to the conventional Wilkinson power divider and realized into MTM added $90^{\circ}$ hybrid coupler. Based on the 10 dB return loss and the $90{\pm}10^{\circ}$ phase shift, the bandwidths of the MTM added $90^{\circ}$ hybrid coupler are 82.25% and 103.5% against the conventional 23% and 52.5%, respectively.

• ETRI Journal
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• 제35권1호
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• pp.150-153
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• 2013

In this letter, a compact and fully printed composite right- and left-handed (CRLH) dual-band power divider is proposed. The branches of the conventional Wilkinson power divider are replaced by subwavelength CRLH phase-shift lines having $+90^{\circ}$ for one frequency and $-90^{\circ}$ for another frequency for dual-band and miniaturization performance. Equations are derived for the even- and odd-mode analysis combined with the dual-band CRLH circuit. A PCS and a WLAN band are chosen as the test case and the circuit approach agrees with the CAD simulation and the measurement. Additionally, the CRLH property is shown with the dispersion diagram and the eightfold size reduction is noted.