• ETRI Journal
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• v.33 no.5
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• pp.814-817
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• 2011

In this letter, the distributions of direct current (DC) coefficients for P-frames in H.264/AVC are analyzed, and the distortion model of the Gaussian source under the quantization of the dead-zone plus-uniform threshold quantization with uniform reconstruction quantizer is derived. Experimental results show that the DC coefficients of P-frames are best approximated by the Laplacian distribution and the Gaussian distribution at small quantization step sizes and at large quantization step sizes, respectively.

• Journal of the Korean Arthroscopy Society
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• v.1 no.1
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• pp.47-51
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• 1997

A torn anterior cruciate ligament(ACL) is the most common serious ligamentous injury to the knee joint. The incidence of ACL tears seems to be increasing, at least partly as a result of the increasing participation of individuals of all ages in high-risk sports. The most commonly used graft source for ACL reconstruction is the autogenous bone-patellar tendon-bone graft unit. Despite a good success record. postoperative complications, such as infection, patellar contracture/patellar baja, patellar fracture, rupture of the patellar tendon, graft failure without reinjury, can occur following ACL surgery. The purpose of this paper is to provide guidelines regarding the key points of the reconstructive procedure in a sequence and how to prevent or minimize the complications that can follow ACL reconstructive surgery. We want this knowledge can help orthopaedic surgeons to understand the reasons for previous and current successes and failures of reconstruction of the ACL, and it can help them to plan the care of patients who have an injury of the ligament.

• The Journal of Korea Robotics Society
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• v.11 no.2
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• pp.51-59
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• 2016

In this paper we present (1) analysis of imaging sonar measurement for two-view relative pose estimation of an autonomous vehicle and (2) bundle adjustment and 3D reconstruction method using imaging sonar. Sonar has been a popular sensor for underwater application due to its robustness to water turbidity and visibility in water medium. While vision based motion estimation has been applied to many ground vehicles for motion estimation and 3D reconstruction, imaging sonar addresses challenges in relative sensor frame motion. We focus on the fact that the sonar measurement inherently poses ambiguity in its measurement. This paper illustrates the source of the ambiguity in sonar measurements and summarizes assumptions for sonar based robot navigation. For validation, we synthetically generated underwater seafloor with varying complexity to analyze the error in the motion estimation.

• Archives of Plastic Surgery
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• v.33 no.6
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• pp.715-722
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• 2006

Purpose: The main advantages of the perforator flap are minimal donor site morbidity, preservation of any main source artery and its thin characteristics. Most perforator flaps for hand reconstruction need primary and secondary procedures such as a flap debulkiness and liposuction etc. However, flap thickness of calf area is thinner than any other perforator flaps. Methods: We performed an anatomical study and clinical application of medial sural artery perforator flap. We found that there are two or more medial sural perforators located on a straight line drawn from the mid-point of popliteal crease to the mid-point of medial malleolus. Most pathway of medial sural artery comes along with this line. It is possible to observe the first perforators almost exactly 8 cm from midpoint of popliteal crease in a distal half circle drawn with a radius of 2 cm. Results: We report 12 cases in 11 patients of hand reconstruction with medial sural perforator free flap from Febrary 2003 to Febrary 2006. Complete healing was possible in 11 cases. Total flap loss for venous insufficiency was in 1 patient. During the follow-up, good contour and full range of motion was observed on hand reconstruction with medial sural perforator free flap. Conclusion: In the authors' experience, this anatomical study made it possible to prepare a diagram of the exact location of the medial sural perforators. This flap can be used to achieve acceptable functional and aesthetic results for hand reconstruction because of its thin characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.837-842
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• 2004

The positions of rotating sound sources have been localized by experiments with the Doppler effects removed. In order to do-Dopplerize the sound signals emitted from moving sources, two kinds of signal reconstruction methods were applied. One is the forward propagation method and the other is the backward propagation method. Forward propagation method analyze the source emission time based on the instantaneous distance between sensors and the assumed source position, then the signals are reconstructed with respect to the emission time. On the other hand, the backward method uses time delay to do-Dopplerize the acquired data for the received time of reference. In both techniques, the reconstructed signal data were processed using beamforming algorithm to produce power distributions at the frequency of interest. Experiments have been carried out for varying frequencies, rotating speeds and the object distances. Forward propagation method has shown better performance in locating source position than the backward propagation method.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.119-122
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• 2001

We derived the resolution of the modified triangular interferometer and described the analysis about distance measurement using the one. Also, to demonstrate the feasibility of distance measurement using the modified triangular interferometer, the incoherent hologram of a two-point source with depth and its numerical reconstruction were presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1101-1106
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• 2004

This study presents the reconstruction of sound field radiated from an automotive engine using equivalent sources. Basic concept of the method presented is to replace the engine noise source with elementary sources of multipoles, e.g., monopoles and dipoles. The so-called Helmholtz equation least-squares (HELS) method can reconstruct the sound radiation fields from spherical geometries in a series expansion of spherical Hankel functions and spherical harmonics. In this paper, multi-Point, multipole equivalent sources are employed to reconstruct the sound field radiated from an automotive engine with a fixed rotation speed. To ensure and improve the accuracy of reconstruction, the spatial filters of multipole coefficients and wave-vectors are adopted for suppressing the adverse effect of high-order multipoles. Optimal filter shapes are designed with regularization parameters minimizing the generalized cross validation (GCV) function between actual and reproduced model. After regeneration of field pressures using the proposed method as many as necessary, the vibro-acoustic field of an engine could be reconstructed by using the BEM-based near-field acoustic holography (NAH) technique in a cost-effective manner.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.459-464
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• 2003

The source current distribution in a heart was reconstructed from the magnetocardiogram (MCG) and its clinical usefulness was demonstrated. MCG was measured using 40-channel superconducting quantum interference device (SQUID) gradiometers for a patient of Wolff-Parkinson-White (WPW) syndrome, which has an accessory pathway between the atria and the ventricles. Reconstruction of source current distribution in a plane below the chest surface was performed using minimum norm estimation (MNE) algorithm and truncated singular value decomposition (SVD), In the simulation, we confirmed that the current distributions. which were computed for the test dipoles, represented well the essential feature of the test current configurations, In the current map of WPW syndrome, we observed abnormal currents that would bypass the atrioventricular junction at a delta wave. However, we could not observe such currents any more after the surgery. These results showed that the obtained current distribution using MCG signals is consistent with the electrical activity in a heart and has clinical usefulness.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2250-2261
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• 2020

Accurate localization of radioactive materials is crucial in homeland security and radiological emergencies. Coded-aperture gamma camera is an interesting solution for such applications and can be developed into portable real-time imaging devices. However, traditional reconstruction methods cannot effectively deal with signal-independent noise, thereby hindering low-noise real-time imaging. In this study, a novel reconstruction method with excellent noise-suppression capability based on a multi-layer perceptron (MLP) is proposed. A coded-aperture gamma camera based on pixel detector and coded-aperture mask was constructed, and the process of radioactive source imaging was simulated. Results showed that the MLP method performs better in noise suppression than the traditional correlation analysis method. When the Co-57 source with an activity of 1 MBq was at 289 different positions within the field of view which correspond to 289 different pixels in the reconstructed image, the average contrast-to-noise ratio (CNR) obtained by the MLP method was 21.82, whereas that obtained by the correlation analysis method was 5.85. The variance in CNR of the MLP method is larger than that of correlation analysis, which means the MLP method has some instability in certain conditions.

• Archives of Plastic Surgery
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• v.32 no.4
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• pp.408-415
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• 2005

Following a transverse rectus abdominis musculocutaneous(TRAM) flap breast reconstruction, denervated state of the flap causes the flap skin prone to thermal injury, calling for special attention. During the last 5 years, 69 breast reconstruction with 72 free TRAM flaps, were performed. Four out of thesse 69 patients sustained burn injury. Heat sources were a warm bag(n=2), heating pad(n=1) and warming light (n=1). The thermal injuries occured from 2 days to 3 months following the reconstruction. Three patients healed with conservative treatment, but one patient required debridement and skin graft. Initially 3 out of 4 patients with the burn had shown superficial 2nd degree burn with small blebs or bullae. However all 4 patients healed with scars. Mechanism of burn injuries of the denervated flap are known to be resulting from; 1) loss of behavioral protection due to denervation of flap with flap elevation and transfer, 2) loss of autonomic thermoregulatory control with heat dissipation on skin flap vasculature contributing to susceptibility of burn injury. 3) changes of immunologic and normal inflammatory response increasing thromboxane, and a fall in substance P & NGF (nerve growth factor). Including the abdominal flap donor site, sensory recovery of the reconstructed breast varies individually from 6 month even to 5 years postoperatively. During this period, wound healing is delayed, resulting in easier scarring compared to that observed in the sensate skin. Patients should be carefully informed and warned of possible burn injuries and taught to avoid exposure to heat source at least until 3 years postoperatively.