• Journal of Biomedical Engineering Research
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• v.30 no.3
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• pp.241-246
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• 2009

Since inappropriate muscle forces mean that people cannot perform some activities related to roles of the muscle, muscle forces have been considered as an important parameter in clinic. Therefore, many methods have been introduced to estimate muscle forces indirectly. One of the methods is muscle tissue dynamics and it is widely used in commercial softwares including musculoskeletal model, such as SIMM. They, however, need motion data captured from 3-dimensional motion analysis system. In this study, we introduced an algorithm to estimate muscle forces in real-time by using joint angles. The heel-rise movements were performed for a normal with 3-dimensional motion analysis system, EMG measurement system, and electrogoniometers. Joint angles obtained from electrogoniometers and EMG signals were used to estimate muscle forces. Simulation was performed to find muscle forces using motion data which was imported into musculoskeletal software. As the results, muscle lengths and forces from the developed algorithm were similar to those from commercial software in pattern. Results of this study would be helpful to implement a tool to calculate reasonable muscle forces in real-time.

• Journal of the Ergonomics Society of Korea
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• v.31 no.4
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• pp.551-556
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• 2012

Objective: This study presents the effect of visual feedback on one-hand gesture performance in vision-based gesture recognition system when people use gestures to control a screen device remotely. Backgroud: gesture interaction receives growing attention because it uses advanced sensor technology and it allows users natural interaction using their own body motion. In generating motion, visual feedback has been to considered critical factor affect speed and accuracy. Method: three types of visual feedback(arrow, star, and animation) were selected and 20 gestures were listed. 12 participants perform each 20 gestures while given 3 types of visual feedback in turn. Results: People made longer hand trace and take longer time to make a gesture when they were given arrow shape feedback than star-shape feedback. The animation type feedback was most preferred. Conclusion: The type of visual feedback showed statistically significant effect on the length of hand trace, elapsed time, and speed of motion in performing a gesture. Application: This study could be applied to any device that needs visual feedback for device control. A big feedback generate shorter length of motion trace, less time, faster than smaller one when people performs gestures to control a device. So the big size of visual feedback would be recommended for a situation requiring fast actions. On the other hand, the smaller visual feedback would be recommended for a situation requiring elaborated actions.

• Structural Engineering and Mechanics
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• v.33 no.6
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• pp.725-745
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• 2009

In this paper, probabilistic seismic performance assessment of a typical non-seismic RC frame building representative of a large inventory of existing buildings in developing countries is conducted. Nonlinear time-history analyses of the sample building are performed with 20 large-magnitude medium distance ground motions scaled to different levels of intensity represented by peak ground acceleration and 5% damped elastic spectral acceleration at the first mode period of the building. The hysteretic model used in the analyses accommodates stiffness degradation, ductility-based strength decay, hysteretic energy-based strength decay and pinching due to gap opening and closing. The maximum inter story drift ratios obtained from the time-history analyses are plotted against the ground motion intensities. A method is defined for obtaining the yielding and collapse capacity of the analyzed structure using these curves. The fragility curves for yielding and collapse damage levels are developed by statistically interpreting the results of the time-history analyses. Hazard-survival curves are generated by changing the horizontal axis of the fragility curves from ground motion intensities to their annual probability of exceedance using the log-log linear ground motion hazard model. The results express at a glance the probabilities of yielding and collapse against various levels of ground motion intensities.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.4
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• pp.187-195
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• 2013

In this paper, firstly, acceleration-time histories were generated by varying strong motion duration in the frequency domain for application to a seismically isolated nuclear power structure, so as to examine the effects of strong motion duration on the behavior of the structure. Secondly, real recorded earthquakes were modified to match the target response spectrum based on the revised SRP 3.7.1(2007) and the modified time histories were applied to the analysis of a seismically isolated nuclear power structure. The obtained values of acceleration and displacement responses of the structure were, finally, compared with the values obtained in case of applying acceleration-time histories generated in the frequency domain to the structure.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.2
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• pp.89-95
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• 2013

Structures in a nuclear power system are designed to be elastic even under an earthquake excitation. However a structural component such as an isolator shows inelastic behavior inherently. For the seismic assessment of nonlinear structures, response history analysis should be performed. In this study, the response of base isolation system was analyzed by response history analysis for the seismic performance assessment. Firstly, several seismic assessment criteria for a nuclear power plant structure were reviewed for the nonlinear response history analysis. Based on these criteria, the spectrum matched ground motion generation method modifying a seed earthquake ground motion time history was adjusted. Using these spectrum matched accelerograms, the distribution of displacement responses of the simplified base isolation system was evaluated. The resulting seismic responses excited by the modified ground motion time histories and the synthesized time history generated by stochastic approach were compared. And the response analysis of the base isolation system considering the different intensities in each orthogonal direction was performed.

• Journal of IKEEE
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• v.24 no.4
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• pp.1109-1116
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• 2020

The matching score evaluating human copying ability can be a good measure to check children's developmental stages, or sports movements like golf swing and dance, etc. It also can be used as HCI for AR, VR applications. This paper presents a method to evaluate the motion similarity between demonstrator who initiates movement and participant who follows the demonstrator action. We present a quantification method of the similarity which utilizes Euclidean L2 distance of Openpose keypoins vector similarity. The proposed method adapts DTW, thus can flexibly cope with the time delayed motions.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.855-860
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• 2006

In the environment where multiple AGVs(Automated Guided Vehicles) operate concurrently in limited space, collisions, deadlocks, and livelocks which have negative effect on the productivity of AGVs occure more frequently. The accelerated motion of an AGV is also one of the factors that make the AGV routing more difficult because the accelerated motion makes it difficult to estimate the vehicle's exact travel time. In this study, we propose methods of avoiding collisions, deadlocks, and livelocks using OAR(Occupancy Area Reservation) table, and selecting best route by estimating the travel time of an AGV in accelerated motion. A set of time-driven simulation works validated the effectiveness of the proposed methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.321-340
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• 2016

The Compressive Video Sensing (CVS) is a useful technology for wireless systems requiring simple encoders but handling more complex decoders, and its rate-distortion performance is highly affected by the quantization of measurements and reconstruction of video frame, which motivates us to presents the Space-Time Quantization (ST-Q) and Motion-Aligned Reconstruction (MA-R) in this paper to both improve the performance of CVS system. The ST-Q removes the space-time redundancy in the measurement vector to reduce the amount of bits required to encode the video frame, and it also guarantees a low quantization error due to the fact that the high frequency of small values close to zero in the predictive residuals limits the intensity of quantizing noise. The MA-R constructs the Multi-Hypothesis (MH) matrix by selecting the temporal neighbors along the motion trajectory of current to-be-reconstructed block to improve the accuracy of prediction, and besides it reduces the computational complexity of motion estimation by the extraction of static area and 3-D Recursive Search (3DRS). Extensive experiments validate that the significant improvements is achieved by ST-Q in the rate-distortion as compared with the existing quantization methods, and the MA-R improves both the objective and the subjective quality of the reconstructed video frame. Combined with ST-Q and MA-R, the CVS system obtains a significant rate-distortion performance gain when compared with the existing CS-based video codecs.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.389-394
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• 2006

Fully flexible cell preserves Hamiltonian in structure, so the symplectic time integrator is applied to the equations of motion. Primarily, generalized leapfrog time integration (GLF) is applicable, but the equations of motion by GLF have some of implicit formulas. The implicit formulas give rise to a complicate calculation for coding and need an iteration process. In this paper, the time integration formulas are obtained for the fully flexible cell molecular dynamics simulation by using the splitting time integration. It separates flexible cell Hamiltonian into terms corresponding to each of Hamiltonian term, so the simple and completely explicit recursion formula was obtained. The explicit formulas are easy to implementation for coding and may be reduced the integration time because they are not need iteration process. We are going to compare the resulting splitting time integration with the implicit generalized leapfrog time integration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.43-44
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• 2006

The performance of the direct adaptive time-delay filter depends on the select time-delay. In this paper, the authors introduce a new scheme to adapt the time-delay which is to be used in conjunction with the direct adaptive command shaping for the improved vibration suppression in flexible motion system. In order to formulate the time-delay adaptation scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct adaptive command shaping filter. By modifying the direct adaptation formula based on the analysis result the authors have established a set of equations to adapt the time-delay toward the optimal value. Simulation results show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression.