• 대한물리의학회지
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• 제6권4호
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• pp.465-473
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• 2011

Purpose : This study was to evaluate gait velocity and muscle activity on 3 different gait conditions in elderly women. Methods : There were one group was 20's generation(n=12), and the other group was over 60's generation (n=12). The velocity of gait was analysed for using the Footscan system, EMG(MP150) for muscle activity. Subjects were measured 3 gait condition(normal, obstacle-10cm, dual obstacle-10cm. Measured values were used by the independent t-test for analysing between groups, and repeated measurement of ANOVA for analysing within group. Results : The results were as follow: velocity and acticities of lower 4 muscles were significantly differences in experimental group. In control group, there were not significantly differences. Contrast-groups were significantly differences of velocity(obstacle, dual obstacle), muscle activities(soleus-dual obstacle, hamstring-all). Conclusion : These results indicate that elderly people are reduced gait ability in dual task, and obstacle gait. So Elderly women need to training obstacle/dual gait for preventing falling.

• 비파괴검사학회지
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• 제26권4호
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• pp.239-245
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• 2006

이방성을 지닌 복합재료에서 측정한 군속도와 램파 방정식을 이용하여 계산한 군속도는 서로 일치하지 않는다. 이러한 차이는 이방성 재료에서 군속도 방향과 위상속도 방향이 서로 일치하지 않는 현상에서 기인된 것이다. 본 연구에서는 램파 분산방정식을 이용하여 이방성을 지닌 단일방향, 양방향, 준등방성 복합재료 판에서 $S_0$모드 위상속도곡선을 전파 방향 변화에 따라 구하고, 위상속도의 역수 값으로 구성되는 slowness surface를 이용하여 군속도의 방향과 크기를 결정하였다. 이와 같이 계산된 군속도는 측정한 군속도와 잘 일치함을 확인하였다.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.222-223
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• 2003

As laser pulse width becomes shortened from nanoseconds to femtoseconds, the effects caused by the dispersions of nonlinear optical mediums, such as group velocity mismatch and group velocity dispersion become considerably significant. The group velocity mismatch and group velocity dispersion are the major factors that lead to a decrease of frequency conversion efficiency and pulse spreading for picosecond and femtosecond pulses. (omitted)

• Structural Engineering and Mechanics
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• 제85권5호
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• pp.645-654
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• 2023

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity-I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

• 사상체질의학회지
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• 제22권4호
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• pp.30-39
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• 2010

1. Objectives This study was carried out to investigate the equilibrium functional difference according to mean velocity of basilar artery with Sasang Constitution. 2. Methods We analyzed the data of 300 adults(194 males, 106 females), who visited oriental hospital of D university for medical examiation, which includes Sasang constitution examination, equilibrium function test, transcranial doppler ultrasonography(TCD). We evaluated the trace length and envelop area of open eyes and closed eyes, mean velocity of basilar artery and analyzed its statistical data. 3. Results and Conclusions 1) Within all subjects, trace length and envelop area of closed eyes were significantly lower, in the order of increased mean velocity of basilar artery group, normal mean velocity of basilar artery group and decreased mean velocity of basilar artery group. 2) No significantly difference was seen between the mean velocity of basilar artery and equilibrium function in Soyangin and Soeumin. 3) When closed eyes, trace length were significantly lower in order of increased mean velocity of basilar artery group, normal mean velocity of basilar artery group and decreased mean velocity of basilar artery group, in Taeeumin.

• Journal of Oral Medicine and Pain
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• 제22권1호
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• pp.167-181
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• 1997

The aim of this study was to investigate the relationship between velocity and factors which could affect the velocity of mandibular movement. For this study, 30 dental students without any masticatory signs and symptoms and 90 patients with temporomandibular disorders(TMD) were selected as the control group and the patients group, respectively. After determining Angle's classification and lateral guidance pattern of occlusion, clinical examination for TMD was perfomed. Velocity and distance of mandibular movements were recorded with BioEGN, reproducibility index of lateral excursions was evaluated by Pantronic(PRI) and BioEGN (BERI) activity in masticatory and cervical muscles were measured with BioEMG, and occlusal contact time and cross-arch unbalance(Total left-right statistics, TLR) on clenching were recorded with T-scan, respectively. The results of this study were as follows : 1. Velocity in the patients was faster than that in the controls in most mandibular movements, but on wide opening and closing movement, result was reverse. 2. Velocity on closing movements were faster than that on opening movements in the control group and a similar tendency was also shown in the patients group. 3. Patients with muscle disorders showed a tendency to have the highest value of velocity of all diagnostic subgroups, while patients with degenerative joint diseases showed a tendency to have the lowest value. 4. Patients with canine guidance showed a tendency to have the highest value of velocity in three subgroups by lateral guidance pattern, while patients with group function showed a tendency to have the lowest value. 5. BERI had a positive correlation with opening velocity on lateral excursion, while TLR had a negative correlation with opening velocity on swallowing. 6. EMG activity on clenching in masticatory muscles had negative correlation with opening velocity on border movements, and on swollowing, while the activity in rest correlated positively with opening velocity on border movements. 7. There were positive correlation between the velocity and the distance in long components of mandibular trajectory.

• Journal of Oral Medicine and Pain
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• 제23권1호
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• pp.21-36
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• 1998

The purpose of this study was analyse the mandibular movements in patients with internal derangement of the temporomandibular joint according to diagnostic subgroups. The author classified patients with internal derangement of the temporomandibular joint into 4 diagnostic subgroups by means of the magnet resonance imagings, and evaluated the clinical signs and the mandibular movements with Mandibular Kinesiograph(MKG) in each subgroups. The mandibular movements, measured in this study, were the types of movement in frontal and sagittal plane, velocities in opening and closing movement, and the opening and closing movement, and the opening and closing velocity pattern. The data were compared between the 5 groups including the normal group. The results were as follows : 1. Pain was more frequently observed in the anterior disc displacement without reduction group than in the anterior disc displacement with reduction group. Sound of joint was more frequently observed in the anterior disc displacement with reduction group, and limitation of mandibular opening movement was more frequently observed in the anterior disc displacement without reduction group. Duration of the anterior disc displacement without reduction group was significantly short compared to that of the anterior disc displacement with reduction group, and duration of the unilateral anterior disc displacement without reduction group was shortest in the experimental group. The frequency of Angle's classifications had not significant correlations between the experimental groups. 2. Active and passive range of the opening movement, maximum protrusive movement, maximum lateral movement toward left side were significantly decreased in the experimental groups compared to the control group, but there was no significant difference in the range of the maximum lateral movement toward right side between the control and experiment groups. In unilateral anterior disc displacement without reduction group, the range of maximum lateral movement toward unaffected side was no significant difference in the range of the maximum lateral movement between toward affected side and toward unaffected side. 3. Maximum opening velocity, maximum closing velocity, average opening velocity, average closing velocity and maximum velocity of terminal tooth contact were significantly decreased in the experimental groups compared to control group. There was no significant difference in maximum opening velocity and maximum velocity of Terminal tooth contact between the subgroups of the experimental group each other, but there was significant difference in maximum closing velocity, average opening velocity and average closing velocity between the subgroups each other. 4. In the frontal plane of the MKG, the frequency of complex deviation type(F-2)pattern was significantly increased in the anterior disc displacement with out reduction group compared to the anterior disc displacement with reduction group and the control group. In the sagittal plane, the frequency of coincident type(S-1)was decreased in the same group. 5. In the maximum opening velocity pattern, the frequency of no-peak type (OV-3)in the unilateral anterior disc displacement with reduction group was significantly increased compared to the control group. The frequency of 1-peak type (OV-1) and 2-peak type (OV-2) was decreased in the anterior disc displacement with out reduction group, but the frequency of no-peak type (OV-3)was increased in the same group. In the maximum closing velocity pattern, the frequency of no-peak type (CV-3) was significantly increased in the anterior disc displacement without reduction group. Compared to the anterior disc displacement with reduction group and the control group. The frequency of 1-peak type (CV-1) and 2-peak type (CV-2) in the anterior disc displacement with reduction group was decreased than that in the control group.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.52-54
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• 2009

A plane wave expansion method(PWEM) was applied for photonic band structure calculation. We examined zero group velocity modes in photonic crystals. The zero group velocity was obtained in second band along G-K direction. We expanded Brillouin zone, and investigated on zero group velocity.

• The Journal of Korean Physical Therapy
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• 제31권5호
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• pp.273-278
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• 2019

Purpose: The purpose of this study was to investigate the effects of three-dimensional virtual reality horse riding simulator training using a head-mounted display on gait and balance in children with cerebral palsy. Methods: Ten children with cerebral palsy were randomly assigned to the horse riding simulator (HRS) group (n=5) or the horse riding simulator with virtual reality (HRSVR) group (n=5). To evaluate balance, center of gravity (COG) sway velocity and total sway distance of each group were assessed using the Wii balance board, and gait speed and stride length of each group were assessed using a gait analysis system. Results: Intra-group comparisons between pre- and post-intervention measures revealed that there were significant changes in all gait and balance variables such as stride length, gait velocity, COG sway velocity and COG sway distance in the HRSVR group (p<0.05). In the HRS group, there were significant changes in all variables except stride length (p<0.05). In addition, inter-group comparisons showed significant differences between the two groups in stride length, gait velocity and COG sway distance except COG sway velocity (p<0.05). Conclusion: The findings of this study suggest that horse riding simulator training combined with 3D virtual reality can be a new positive therapeutic approach for improving functional performance in children with cerebral palsy.

• 한국음향학회지
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• 제25권3호
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• pp.107-112
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• 2006

판재를 따라 전파하는 Lamb wave (램파)는 주파수에 따라 속도가 변하는 분산특성을 갖는다. 일반적으로 등방성 재료에서는 파수 벡터 방향과 에너지 흐름 방향은 같아, 파면이 원형을 유지하면서 전파하지만, 복합재료와 같이 이방성재료에서는 파수 벡터와 에너지 흐름 방향이 서로 다르다. 따라서 이방성 재료에서 하나의 속도에서 다른 속도로 전환하려면 방향을 교정해야 하고 이에 따라 크기도 달라지게 된다. 본 연구에서는 복합재료 판재에서 전파하는 램파 분산방정식을 이용하여 대칭, 비대칭 모드의 분산선도를 작성하였고, 각도에 따라구한 위상속도 분산선도에서 얻어진 위상속도 값으로 slowness surface를 구한 후, 이로부터 군속도의 크기와 방향을 교정하였고, 이를 실험적으로 측정한 속도값과 비교하여 서로 일치함을 확인하였다.