• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.2
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• pp.179-185
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• 2000

The purpose of this study was to develop an osteogenic, biodegradable material using polymer and BMP. It was designed to have structural function and be moldable, for the reconstruction of load bearing areas and deformities of various configurations. Bone apatite was added to Poly(L-lactide)(PLLA) and made porous for osteoconductability and ease of BMP loading. The materials, with or without BMP purified from porcine bone matrix, were evaluated in cranial bone defect models in rats for biocompatibility and bone regeneration capability. The following results were obtained: The PLLA-BMP material with BMP added to the polymer showed 30% healing of cranial bone defects in rats during the 2 weeks to 3 months period of observation. The moldable PLLA agent without BMP also showed 25% bone healing capacity. Although new bone formation was incomplete in the critical size defect of rat cranium, it can be concluded that the unique moldability of those agents makes them useful for the reconstruction of various bone defects and maxillofacial deformities.

• Journal of Information Display
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• v.6 no.4
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• pp.26-34
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• 2005

In this paper, a new rectification scheme to transform the uncalibrated stereo image pair into the calibrated one is suggested and its performance is analyzed by applying this scheme to the reconstruction of the intermediate views for multi-view stereoscopic display. In the proposed method, feature points are extracted from the stereo image pair by detecting the comers and similarities between each pixel of the stereo image pair. These detected feature points, are then used to extract moving vectors between the stereo image pair and the epipolar line. Finally, the input stereo image pair is rectified by matching the extracted epipolar line between the stereo image pair in the horizontal direction. Based on some experiments done on the synthesis of the intermediate views by using the calibrated stereo image pairs through the proposed rectification algorithm and the uncalibrated ones for three kinds of stereo image pairs; 'Man', 'Face' and 'Car', it is found that PSNRs of the intermediate views reconstructed from the calibrated images improved by about 2.5${\sim}$3.26 dB than those of the uncalibrated ones.

• Archives of Plastic Surgery
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• v.48 no.1
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• pp.44-48
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• 2021

Previously reported nipple-areolar complex reconstruction (NAR) methods involve multiple incisions and wide skin redraping, which increase retraction forces and heighten the risk of nipple-areolar complex (NAC) flattening. We introduce a NAR method using the long V-Y advancement technique that can overcome these disadvantages. A V-shaped flap is designed with the width of the flap base 4-5 mm larger than the diameter of the normal nipple. The flap length is designed to be at least 2.5 times its width. Dissection is performed to the top of the artificial dermal matrix or muscle layer. The nipple is constructed with the same projection as the contralateral side by folding the elevated flap. The tip of the elevated flap is apposed in the middle of the donor defect to minimize the deformity during donor site closure. A 3-point skin suture is applied to the upper third of the folded flap to mold its shape. Using this long V-Y advancement technique, we successfully decreased skin tension in NAC flaps and improved the maintenance of reconstructed nipple projection. The long V-Y advancement technique provides an easy, simple NAR method, effectively maintaining longer nipple projections and reducing breast deformities, especially in Asian women with relatively large nipples.

• Archives of Craniofacial Surgery
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• v.23 no.1
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• pp.39-42
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• 2022

The reconstruction of total lower eyelid defects is challenging to plastic surgeons due to the complicated anatomical structure of the eyelid. In addition, in the setting of cancer excision, the resection is deep, which requires some volume augmentation. However, in some cases, free tissue transfer is not applicable. We report a case of using a temporoparietal fascia flap (TPFF) for reconstructing a total lower eyelid defect. A large erythematous mass in an 83-year-old woman was diagnosed as squamous cell carcinoma by biopsy. After wide excision, the defect size was about 8×6 cm. The lower eyelid structures including the tarsus were removed. The TPFF including the superficial temporal artery was elevated and inset to the defect area. After the flap inset, a split-thickness skin graft with an acellular dermal matrix was performed on the fascial flap. There were no wound problems such as infection, dehiscence, or necrosis. After the patient's discharge, partial skin graft loss and ectropion occurred. The complications resolved spontaneously during the postoperative period. We report a case of reconstructing a lower eyelid defect using a TPFF. A TPFF can be applied to patients with large defects for whom free tissue transfer surgery is not appropriate as in this case.

• Tissue Engineering and Regenerative Medicine
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• v.19
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• pp.553-563
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• 2022

BACKGROUND: Autologous fat grafting is one of the most common procedures used in plastic surgery to correct soft tissue deficiency or depression deformity. However, its clinical outcomes are often suboptimal, and lack of metabolic and architectural support at recipient sites affect fat survival leading to complications such as cyst formation, calcification. Extracellular matrix-based scaffolds, such as allograft adipose matrix (AAM) and poly(lactic-co-glycolic) acid (PLGA), have shown exceptional clinical promise as regenerative scaffolds. Magnesium hydroxide (MH), an alkaline ceramic, has attracted attention as a potential additive to improve biocompatibility. We attempted to combine fat graft with regenerative scaffolds and analyzed the changes and viability of injected fat graft in relation to the effects of injectable natural, and synthetic (PLGA/MH microsphere) biomaterials. METHODS: In vitro cell cytotoxicity, angiogenesis of the scaffolds, and wound healing were evaluated using human dermal fibroblast cells. Subcutaneous soft-tissue integration of harvested fat tissue was investigated in vivo in nude mouse with random fat transfer protocol Fat integrity and angiogenesis were identified by qRT-PCR and immunohistochemistry. RESULTS: In vitro cell cytotoxicity was not observed both in AAM and PLGA/MH with human dermal fibroblast. PLGA/MH and AAM showed excellent wound healing effect. In vivo, the AAM and PLGA/MH retained volume compared to that in the only fat group. And the PLGA/MH showed the highest angiogenesis and anti-inflammation. CONCLUSION: In this study, a comparison of the volume retention effect and angiogenic ability between autologous fat grafting, injectable natural, and synthetic biomaterials will provide a reasonable basis for fat grafting.

• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.245-250
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• 2011

Parallel imaging technique can provide several advantages for a multitude of MRI applications. Especially, in SENSE technique, sensitivity maps were always required in order to determine the reconstruction matrix, therefore, a number of difference approaches using sensitivity information from coils have been demonstrated to improve of image quality. Moreover, many filtering methods were proposed such as adaptive matched filter and nonlinear diffusion technique to optimize the suppression of background noise and to improve of image quality. In this study, we performed SENSE reconstruction using computer simulations to confirm the most suitable method for the feasibility of filtering effect and according to changing order of polynomial fit that were applied on variation of spatial resolution of sensitivity map. The image was obtained at 0.32T(Magfinder II, Genpia, Korea) MRI system using spin-echo pulse sequence(TR/TE = 500/20 ms, FOV = 300 mm, matrix = $128{\times}128$, thickness = 8 mm). For the simulation, obtained image was multiplied with four linear-array coil sensitivities which were formed of 2D-gaussian distribution and the image was complex white gaussian noise was added. Image processing was separated to apply two methods which were polynomial fitting and filtering according to spatial resolution of sensitivity map and each coil image was subsampled corresponding to reduction factor(r-factor) of 2 and 4. The results were compared to mean value of geomety factor(g-factor) and artifact power(AP) according to r-factor 2 and 4. Our results were represented while changing of spatial resolution of sensitivity map and r-factor, polynomial fit methods were represented the better results compared with general filtering methods. Although our result had limitation of computer simulation study instead of applying to experiment and coil geometric array such as linear, our method may be useful for determination of optimal sensitivity map in a linear coil array.

• Archives of Plastic Surgery
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• v.46 no.6
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• pp.550-557
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• 2019

Background In recent years, breast implants have been frequently placed in the subcutaneous pocket, in the so-called prepectoral approach. We report our technique of prepectoral implant-based breast reconstruction (IBR), as well as its surgical and aesthetic outcomes, in comparison with subpectoral IBR. We also discuss relevant considerations and pitfalls in prepectoral IBR and suggest an algorithm for the selection of patients for IBR based on our experiences. Methods We performed 79 immediate breast reconstructions with a breast implant and an acellular dermal matrix (ADM) sling, of which 47 were subpectoral IBRs and 32 were prepectoral IBRs. Two-stage IBR was performed in 36 cases (20 subpectoral, 16 prepectoral), and direct-to-implant IBR in 43 cases (27 prepectoral, 16 subpectoral). The ADM sling supplemented the inferolateral side of the breast prosthesis in the subpectoral group and covered the entire anterior surface of the breast prosthesis in the prepectoral group. Results The postoperative pain score was much lower in the prepectoral group than in the subpectoral group (1.78 vs. 7.17). The incidence of seroma was higher in the prepectoral group (31.3% vs. 6.4%). Other postoperative complications, such as surgical site infection, flap necrosis, implant failure, and wound dehiscence, occurred at similar rates in both groups. Animation deformities developed in 8.5% of patients in the subpectoral group and rippling deformities were more common in the prepectoral group (21.9% vs. 12.8%). Conclusions The indications for prepectoral IBR include moderately-sized breasts with a thick well-vascularized mastectomy flap and concomitant bilateral breast reconstruction with prophylactic mastectomy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.9
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• pp.3782-3796
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• 2020

A three-dimensional (3D) reconstruction is an important research area in computer vision. The ability to detect and match features across multiple views of a scene is a critical initial step. The tracking matrix W obtained from a 3D reconstruction can be applied to structure from motion (SFM) algorithms for 3D modeling. We often fail to generate an acceptable number of features when processing face or medical images because such images typically contain large homogeneous regions with minimal variation in intensity. In this study, we seek to locate sufficient matching points not only in general images but also in face and medical images, where it is difficult to determine the feature points. The algorithm is implemented on an adaptive threshold value, a scale invariant feature transform (SIFT), affine SIFT, speeded up robust features (SURF), and affine SURF. By applying the algorithm to face and general images and studying the geometric errors, we can achieve quasi-dense matching points that satisfy well-functioning geometric constraints. We also demonstrate a 3D reconstruction with a respectable performance by applying a column space fitting algorithm, which is an SFM algorithm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.8-15
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• 2006

Obstacle detection is an important task for many mobile robot applications. The methods using stereo vision and optical flow are computationally expensive. Therefore, this paper presents a vision-based obstacle detection method using only two view images. The method uses a single passive camera and odometry, performs in real-time. The proposed method is an obstacle detection method using 3D reconstruction from taro views. Processing begins with feature extraction for each input image using Dr. Lowe's SIFT(Scale Invariant Feature Transform) and establish the correspondence of features across input images. Using extrinsic camera rotation and translation matrix which is provided by odometry, we could calculate the 3D position of these corresponding points by triangulation. The results of triangulation are partial 3D reconstruction for obstacles. The proposed method has been tested successfully on an indoor mobile robot and is able to detect obstacles at 75msec.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.36-44
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• 2012

Electrical impedance tomography is a relatively new imaging modality in which the internal conductivity (or resistivity) distribution of a object is reconstructed based on the injected currents and measured voltages through the electrodes placed on the surface of the object. In this paper, it is assumed that the relationship between the resistivity distribution and the resistance of electrodes is linear. From this linear relation, the weighting matrix can be obtained and modified iterative Landweber method is applied to estimate the internal resistivity distribution. Additionally, to accelerate the convergence rate and improve the spatial resolution of the reconstructed image, optimal step lengths for the iterative Landweber method are computed from the objective function in the least-square sense. The numerical experiments have been performed to illustrate the superior reconstruction performance of the proposed scheme.