• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.265-272
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• 2015

A new technology on video frame rate up-conversion (FRUC) is presented by combining the median filter and motion estimation (ME) with an occlusion detection (OD) method. First, ME is performed to have a motion vector. Then, the OD method is used to refine motion vector in the occlusion region. Since the wrong motion vector can be obtained with high possibility in the occluded area, a median filtering that less depends on the motion vector is applied to that area, and since the motion vector is continuous and robust in the non-occluded area, BDMC(Bi-Directional Motion Compensated interpolation) is applied to obtain interpolated image in that area. BDMC using the bi-directional motion vectors achieves good results when continuity and robustness of the motion vector is higher. Experimental results show that the proposed algorithm provides better performance than the conventional approach. The average gain of PSNR (Peak Signal to Noise Ratio) is approximately 0.16 dB in the test sequences compared with BDMC.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.400-408
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• 2022

Objective: The purpose of this study is to compare EMG activity during horticulture motion and upper limb rehabilitation motion, to confirm whether horticulture motion is suitable for upper extremity rehabilitation of hemiparesis. Design: Three-group cross-sectional design. Methods: The 45 subjects were divided into three groups: hemiparesis (n=15), elderly (n=15) and healthy (n=15). We have recorded EMG signals of six upper limb muscles Upper trapezius (UT), Middle deltoid (MD), Anterior deltoid (AD), Biceps brachii (BB), Triceps brachii (TB), Brachioradialis (BR) during horticultural motions and three upper limb rehabilitative motions. The dependent variables were peak EMG, integral EMG, co-contraction ratio. A two-way repeated measures ANOVA was used to compare the horticultural motion and rehabilitation motion of the three groups. Results: The peak EMG was significantly different in MD, AD, BB, TB according to the motion(p<0.05), and the UT, BB were significant differences according to the group(p<0.05). The integral EMG was significantly different in MD, AD, BB, TB, BR according to the motion(p<0.05), and the BB were significant differences according to the group(p<0.05). The co-contraction ratio was significantly different in TB/BB according of the motion, and there was no difference between the groups. Conclusions: As a result of this study, horticultural motion alone was insufficient for upper arm rehabilitation, and horticultural motion alone was insufficient to induce continuous activity of the forearm.

• Journal of Broadcast Engineering
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• v.12 no.6
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• pp.565-573
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• 2007

In this paper, we propose a method to select motion vector predictor by considering prediction structure of a multi view content for coding efficiency of multi view coding which is being standardized in JVT. Motion vector of a different tendency is happened while carrying out temporal and view reference prediction of multi-view video coding. Also, due to the phenomena of motion vectors being searched in both temporal and view order, the motion vectors do not agree with each other resulting a decline in coding efficiency. This paper is about how the motion vector predictor are selected with information of prediction structure. By using the proposed method, a compression ratio of the proposed method in multi-view video coding is increased, and finally $0.03{\sim}0.1$ dB PSNR(Peak Signal-to-Noise Ratio) improvement was obtained compared with the case of JMVM 3.6 method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1231-1237
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• 2000

Dynamics of a rotating cantilever beam near its critical angular speed is investigated in this paper. The external, force is idealized as a periodic function which has the same period as the rotati ng frequency of the beam. The equations of motion are derived and transformed into a dimensionless form. A prescribed spin-up motion is employed for the rotating motion. Numerical study shows that the steady state and the transient responses of the beam are affected by the spin-up time constant and there exists a time constant at which the maximum transient response becomes minimum.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.2
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• pp.111-118
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• 2023

The 2017 Pohang earthquake afflicted more significant economic losses than the 2016 Gyeongju earthquake, even if these earthquakes had a similar moment magnitude. This phenomenon could be due to local site conditions that amplify ground motions. Local site effects could be estimated from methods using the horizontal-to-vertical spectral ratio, standard spectral ratio, and the generalized inversion technique. Since the generalized inversion method could estimate the site effect effectively, this study modeled the site effects in the Korean peninsula using the generalized inversion technique and the Fourier amplitude spectrum of ground motions. To validate the method, the site effects estimated for seismic stations were tested using recorded ground motions, and a ground motion prediction equation was developed without considering site effects.

• Smart Structures and Systems
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• v.33 no.3
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• pp.217-225
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• 2024

In this study, an electromagnetic dynamic vibration suppressor and energy harvester is designed and studied. In this system, a gear mechanism is used to convert the linear motion to continuous rotary motion. Governing equations of motion for the system are derived and validated using the experimental results. Effects of changing the main parameters of the presented system, such as mass ratio, stiffness ratio and gear ratio on the electro-mechanical behavior of system are investigated. Moreover, using so-called Weighted Cost Function, the optimum parameters of the system are obtained. Finally, it is shown that the presented electromagnetic dynamic vibration absorber not only can reduce the undesired vibration of the main system but also it can harvest acceptable electrical energy.

• Structural Engineering and Mechanics
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• v.27 no.4
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• pp.425-438
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• 2007

Large changes in stiffness associated with cracking and yielding of reinforced concrete sections may be expected to occur during the dynamic response of reinforced concrete frames to earthquake ground shaking. These changes in stiffness in stories that experience cracking might be expected to cause relatively large peak interstory drift ratios. If so, accounting for such changes would add complexity to seismic design procedures. This study evaluates changes in an index parameter to establish whether this effect is significant. The index, known as the coefficient of distortion (COD), is defined as the ratio of peak interstory drift ratio and peak roof drift ratio. The sensitivity of the COD is evaluated statistically for five- and nine-story reinforced concrete frames having either uniform story heights or a tall first story. A suite of ten ground motion records was used; this suite was scaled to five intensity levels to cause varied degrees of damage to the concrete frame elements. Ground motion intensity was found to cause relatively small changes in mean CODs; the changes were most pronounced for changes in suite scale factor from 0.5 to 1 and from 1 to 4. While these changes were statistically significant in several cases, the magnitude of the change was sufficiently small that values of COD may be suggested for use in preliminary design that are independent of shaking intensity. Consequently, design limits on interstory drift ratio may be implemented by limiting the peak roof drift in preliminary design.

• Physical Therapy Korea
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• v.27 no.4
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• pp.241-249
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• 2020

Background: Prolonged standing during work causes a lower extremity pain and disorders. Patellofemoral pain syndrome (PFPS) is one of the common diagnoses of the knee pain. Although the etiology of PFPS is not completely understood, it is considered to be multifactorial. Objects: The purpose of this study was to investigate difference in strength of knee muscles, quadriceps:hamstring muscles strength ratio (Q:H ratio), asymmetry ratio of knee muscles strength and dorsiflexion range of motion (ROM) between standing workers with and without PFPS. Methods: Twenty-eight standing workers with PFPS and 26 age-, height-, and weight-matched standing workers without PFPS participated in this study. A tension sensor measured knee muscle strength, and motion sensor measured dorsiflexion ROM. The asymmetry ratio of knee muscles was calculated by a specific formula using the knee muscles strength of the dominant side and the sound side. An independent t-test was used to identify significant differences in the strength, ROM, Q:H ratio, and asymmetry ratio between the PFPS and normal groups. Results: The standing worker with PFPS have significantly lower dorsiflexion ROM (p < 0.000) and higher asymmetry ratio of the hamstring muscles strength (p < 0.000) compare to the standing worker without PFPS. No significant differences were seen in the strength of quadriceps muscle and hamstring muscles, Q:H ratio, and asymmetry ratio of quadriceps muscle strength. Conclusion: There was a significant difference in the asymmetry ratio of the isometric hamstring muscle strength. This finding suggests that the asymmetry ratio of isometric hamstring muscle strength may be more important than measuring only the hamstring muscle strength of the PFPS side. Furthermore, the results of this study showed a significant difference in dorsiflexion ROM between the standing industrial workers with and without PFPS. Dorsiflexion ROM and isometric hamstring muscle strength should be considered when evaluating the subjects with PFPS.

• Journal of Korea Multimedia Society
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• v.20 no.11
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• pp.1711-1719
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• 2017

In this paper, we propose a method of the zoom motion estimation for the depth video coding. The proposed method calculates the zoom ratio using the average of the depth values in the current block and in the reference block. It resizes the reference block by the zoom ratio and interpolates the reference block to size of the current block. It compares the current block with the reference block that is obtained by subtracting the average of pixels from the current block to the reference block in order to find the reference block that is the best closest one to the current block. The results of the simulation for the proposed method show that the motion estimation errors are significantly reduced.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.155-163
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• 1999

In this study, single cylinder engines with different tumble ratio were made to find out in-cylinder fluid motion and flame propagation. Tumble ratio derived from the steady state flow rig test. Flame propagation speed was obtained using cylinder head gasket ionization probe and the piston ionization probe. And the combustion pressure in cylinder was measured to analyze the combustion characteristics. In case of high tumble engine, BSFC and BSHC were decreased and BSNOx was increased at part load test. Also BMEP and combustion peak pressure was increased at full load test. Tumble flow motion had an great effects on initial burning period rather than main burning period in part load test.