• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.956-965
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• 2008

H.264/AVC is the newest video coding standard of ITU-T VCEG and the ISO/IEC MPEG, offering a significant performance improvement over previous video coding standards. However, the computational complexity of H.264/AVC is drastically increased because of new technologies such as intra prediction, variable block size, quarter-pels motion estimation/compensation, etc. In this paper, we propose a fast intra prediction scheme which has two step processing. The first step is a fast block size decision which can be calculated only in one block without considering all cases of $4{\times}4$ block and $16{\times}16$ block. The complexity of the intra prediction can be reduced by using boundary difference values of macroblock. After selecting the block size, we can make mode decision using the neighbouring reference pixels and representative pixels of the block in the second step. The experimental results show that the proposed algorithm saved on the average 41.5% encoding time without any significant PSNR losses.

• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.516-524
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• 2008

This paper presents a new modeling technique for the simulation of cloth specific characteristics with a set of hard constraints using an implicit constraint enforcement scheme. A conventional explicit Baumgarte constraint stabilization method has several defects. It requires users to pick problem-dependent coefficients to achieve fast convergence and has inherent stabilization limits. The proposed implicit constraint enforcement method is stable with large time steps, does not require problem dependent feed-back parameters, and guarantees the natural physics-based motion of an object. In addition, its computational complexity is the same as the explicit Baumgarte method. This paper describes a formulation of implicit constraint enforcement and provides a constraint error analysis. The modeling technique for complex components of cloth such as seams, buttons, sharp creases, wrinkles, and prevention of excessive elongation are explained. Combined with an adaptive constraint activation scheme, the results using the proposed method show the substantial enhancement of the realism of cloth simulations with a corresponding savings in computational cost.

• Journal of Korean Neurosurgical Society
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• v.37 no.5
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• pp.364-369
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• 2005

Objective: Spinal instrumentation without fusion often fails due to biological failure of intervertebral joints (spontaneous fusion, degeneration, etc). The purpose of this study is to investigate the influence of fixation rigidity on viability of intervertebral joints. Methods: Twenty pigs in growing period were subjected to posterior segmental fixation. Twelve were fixed with a rigid fixation system(RF) while eight were fixed with a flexible unconstrained implant(FF). At the time of the surgery, a scoliosis was created to monitor fixation adequacy. The pigs were subjected to periodic radiological examinations and 12pigs (six in RF, six in FF) were euthanized at 12-18months postoperatively for analysis. Results: The initial scoliotic curve was reduced from $31{\pm}5^{\circ}$ to $27{\pm}8^{\circ}$ in RF group (p=0.37) and from $19{\pm}4^{\circ}$ to $17{\pm}5^{\circ}$ in FF group (p=0.21). Although severe disc degeneration and spontaneous fusion of facet joints were observed in RF group, disc heights of FF group were well maintained without major signs of degeneration. Conclusion: The viability of the intervertebral joints depends on motion spinal fixation. Systems allowing intervertebral micromotion may preserve the viability of intervertebral discs and the facet joint articular cartilages while maintaining a reasonably stable fixation.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.1-10
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• 1998

In the dynamic soil-structure interaction(SSI) analysis, numerous uncertain parameters are involved. They include the uncertainties in the definition of input motions, modeling of soil-structure interaction systems. analysis techniques, etc. This paper presents the results of parametric studies of the seismic responses of a reactor containment structure built on the viscoelastic layered soil. Among the numerous parameter, this study concentrates on the effects of definition point of the input motion, embedment of structure to the base soil, thickness of the top soil layer, and rigidity of the base soil. The substructure method using frequency independent impedances is adopted. The method is based on the mode superposition method in time domain using the composite modal damping values of th SSI system computed from the ratio of dissipated energy to the strain energy for each model. From the study results, the sensitivity of each parameter on the earthquake responses has been suggested for the practical application of the substructure method of SSI analysis.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.311-317
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• 2010

In the paper, we propose an improved mobility method of modular robots by physical docking in the uneven environments. The modular robot system consists of autonomous docking device, 3 DOF robotic arm, motion controller, and main controller. Real-time location and direction of the robot are estimated using inner GPS and they are used to control direction and path of each robot for physical docking between modular robots. We design a navigation algorithm of modular robot using physical docking and cooperative navigation in the environment with broken road and low stair. The proposed method is verified by navigation experiments of three developed modular robots in the uneven environments.

• The Korean Journal of Emergency Medical Services
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• v.19 no.3
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• pp.19-32
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• 2015

Purpose: This study examined the effect of wearing personal protective equipment (PPE) on cardiopulmonary resuscitation (CPR), positive airway pressure, and the posture of emergency medical technicians (EMTs) when conducting CPR. Methods: Twenty 119 EMTs performed 30:2 CPR on a manikin for 4 min. Imaging data were digitized with Kwon3D XP (version 4.0). Data were collected by analyzing the motion when starting in one cycle, such as pressing to the maximum and in the final position (relaxed), and were analyzed with SPSS 18.0. Results: The angle of the elbow joints was significantly reduced (p < .05). The trunk angle was statistically significantly (p < .01, p < .001) increased. The angular velocities of the shoulder joint and left elbow joint were reduced (p > .05). The angular velocity of the trunk was significantly reduced in the starting and maximum compression postures. The hand-escape time was increased. The average compression depth was increased but not significantly (p > .05). The positive airway pressure was reduced (p > .05). Conclusion: The angle of the elbow joints and the angular velocity of the trunk were reduced, and the angle of the trunk was increased. The success of CPR and positive airway pressure was reduced.

• Journal of Ocean Engineering and Technology
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• v.27 no.5
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• pp.63-69
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• 2013

The mooring lines of a floating type offshore plant are known to show wide banded and bimodal responses. These phenomena come from a combination of low and high frequency random load components, which are derived from the drift-restoring motion characteristic and wind- sea, respectively. In this study, fatigue models were applied to predict the fatigue damage of mooring lines under those loads, and the result were compared. For this purpose, seven different fatigue damage prediction models were reviewed, including mathematical formula. A FPSO (floating, production, storage, and offloading) with a $4{\times}4$ spread catenary mooring system was selected as a numerical model, which was already installed at an offshore area of West Africa. Four load cases with different combinations of wave and wind spectra were considered, and the fatigue damage to each mooring line was estimated. The rain flow fatigue damage for the time process of the mooring tension response was compared with the results estimated by all the fatigue damage prediction models. The results showed that both Benasciutti-Tovo and JB models could most accurately predict wide banded bimodal fatigue damage to a mooring system.

• Archives of Craniofacial Surgery
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• v.12 no.2
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• pp.86-92
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• 2011

Purpose: The purpose of this study was to investigate the possibility that a dynamic facial composite flap with sensory and motor nerves could be made available from donor facial composite tissue. Methods: The faces of 3 human cadavers were dissected. The authors studied the donor faces to assess which facial composite model would be most practicable. A "panorama facial flap" was excised from each facial skeleton with circumferential incision of the oral mucosa, lower conjunctiva and endonasal mucosa. In addition, the authors measured the available length of the arterial and venous pedicles, and the sensory nerves. In the recipient, the authors evaluated the time required to anastomose the vessels and nerve coaptations, anchor stitches for donor flaps, and skin stitches for closure. Results: In the panorama facial flap, the available anastomosing vessels were the facial artery and vein. The sensory nerves that required anastomoses were the infraorbital nerve and inferior alveolar nerve. The motor nerve requiring anstomoses was the facial nerve. The vascular pedicle of the panorama facial flap is the facial artery and vein. The longest length was 78 mm and 48 mm respectively. Sensation of the donor facial composite is supplied by the infraorbital nerve and inferior alveolar nerve. Motion of the facial composite is supplied by the facial nerve. Some branches of the facial nerve can be anastomosed, if necessary. Conclusion: The most practical facial composite flap would be a mid and lower face flap, and we proposed a panorama facial flap that is designed to incorporate the mid and lower facial skin with and the unique tissue of the lip. The panorama facial composite flap could be considered as one of the practicable basic models for facial allotransplantation.

• Structural Engineering and Mechanics
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• v.73 no.4
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• pp.427-436
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• 2020

The use of final IGS precise orbit and clock products for high-rate GNSS-PPP proved its effectiveness in capturing dynamic displacement of engineering structures caused by earthquakes. However, the main drawback of using the final products is that they are available after approximately two weeks of data collection, which is not suitable for timely measures after an event. In this study, the use of ultra-rapid products (observed part), which are available after a few hours of data collection, and rapid products, which are available in less than 24 hrs, are investigated and their results are compared to the more precise final products. The tests are designed such that harmonic oscillations with different frequencies and amplitudes and ground motion of a simulated real earthquake are generated using a single axis shake table and the PPP was used to capture these movements by monitoring time-change of the table positions. To evaluate the accuracy of PPP using ultra-rapid, rapid and final products, their results were compared with relative GNSS positioning and LVDT (Linear Variable Differential Transformer) data, treated as reference. The results show that the high-rate GNSS-PPP solutions based on the three products can capture frequencies of harmonic oscillations and dynamic displacement with good accuracy. There were slight differences between ultra-rapid, rapid and final products, where some of the tested events indicated that the latter two produced are more accurate and provide better results compared to the ultra-rapid product for monitoring short-term dynamic displacements.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.479-485
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• 2007

In this paper, a hierarchical simulation with an approximate implicit method is proposed in order to efficiently and plausibly animate mass-spring based cloth models. The proposed hierarchical simulation method can generate realistic motion of extremely fine mesh in interactive rate. The proposed technique employs a fast and stable simulation method which approximates the implicit integration. Although the approximate method is efficient, it is extremely inaccurate and shows excessively damped behavior. The hierarchical simulation technique proposed in this paper constructs multi-level mesh structure in order to represent the realistic appearance of cloth model and performs simulation on each level of the mesh with constraints that enforce some of the mass-points of current level to follow the movement of the previous level. This hierarchical method efficiently generates a plausible movement of a cloth model composed of large number of mass points. Moreover, this hierarchical method enables us to generate realistic wrinkles on the cloth, and the wrinkle pattern on the cloth model can be easily controlled because we can specify different contraction resistance force of springs according to their hierarchical level.