• Archives of Plastic Surgery
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• 제37권5호
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• pp.607-612
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• 2010

Purpose: Maxillectomy for malignant tumor resection often leads to functional and aesthetic sequalae. Reconstruction following maxillectomy has been a challenging problem in the field of head and neck cancer surgery. In this article, we described three dimensional midface reconstructions using free flaps and their functional and aesthetic outcomes. Methods: We reconstructed 35 cases of maxillectomy defects using 9 radial forearm free flaps, 7 lattisimus dorsi musculocutaneous free flaps, 6 rectus abdominis musculocutaneous free flaps, 4 fibular osteocutaneous free flaps, and 9 anterolateral thigh free flaps, respectively. We classified post-maxillectomy defects by Brown's classification. 1 Articulation clarity was measured with picture consonant articulation test. Swallowing function was evaluated with the University of Washington quality-of-life Head and Neck questionnaire by 4 steps.2 Aesthetic outcomes were checked to compare preoperative with postoperative full face photographs by 5 medical doctors who did not involve in our operation. Results: The average articulation clarity was 92.4% (100-41.9%). 27 (81.9%) patients were able to eat an unrestricted diet. Aesthetic results were considered excellent in 18 patients (51.4%). Functional results were best in the group reconstructed with fibular osteocutaneous free flap. Considering the range of wide excision, aesthetic results is best in the group reconstructed with anterolateral thigh free flap. Conclusion: The free flap is a useful technique for the reconstruction of the midface leading to good results, both functionally and aesthetically. Especially, because osteocutaneous flap such as fibular osteocutaneous free flap offered bone source for osteointegrated implant, It produces the best functional results. And perforator flap like as anterolateral thigh free flap reliably provides the best aesthetic results, because it provides sufficient volume and has no postoperative volume diminution.

• 대한의용생체공학회:의공학회지
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• 제35권5호
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• pp.132-141
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• 2014

In an ordinary CT scan, a large number of projections with full field-of-view (FFOV) are necessary to reconstruct high resolution images. However, excessive x-ray dosage is a great concern in FFOV scan. Region-of-interest (ROI) CT or sparse-view CT is considered to be a solution to reduce x-ray dosage in CT scanning, but it suffers from bright-band artifacts or streak artifacts giving contrast anomaly in the reconstructed image. In this study, we propose an image reconstruction method to eliminate the bright-band artifacts and the streak artifacts simultaneously. In addition to the ROI scan for the interior projection data with relatively high sampling rate in the view direction, we get sparse-view exterior projection data with much lower sampling rate. Then, we reconstruct images by solving a constrained total variation (TV) minimization problem for the interior projection data, which is assisted by the exterior projection data in the compressed sensing (CS) framework. For the interior image reconstruction assisted by the exterior projection data, we implemented the proposed method which enforces dual data fidelity terms and a TV term. The proposed method has effectively suppressed the bright-band artifacts around the ROI boundary and the streak artifacts in the ROI image. We expect the proposed method can be used for low-dose CT scans based on limited x-ray exposure to a small ROI in the human body.

• 대한의용생체공학회:의공학회지
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• 제35권5호
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• pp.151-159
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• 2014

Computed tomography (CT) is one of the most widely used medical imaging modality. However, substantial x-ray dose exposed to the human subject during the CT scan is a great concern. Region-of-interest (ROI) CT is considered to be a possible solution for its potential to reduce the x-ray dose to the human subject. In most of ROI-CT scans, the ROI is set to a circular shape whose diameter is often considerably smaller than the full field-of-view (FOV). However, an arbitrarily shaped ROI is very desirable to reduce the x-ray dose more than the circularly shaped ROI can do. We propose a new method to make a non-circular convex-shaped ROI along with the image reconstruction method. To make a ROI with an arbitrary convex shape, dynamic collimations are necessary to minimize the x-ray dose at each angle of view. In addition to the dynamic collimation, we get the ROI projection data with slightly lower sampling rate in the view direction to further reduce the x-ray dose. We reconstruct images from the ROI projection data in the compressed sensing (CS) framework assisted by the exterior projection data acquired from the pilot scan to set the ROI. To validate the proposed method, we used the experimental micro-CT projection data after truncating them to simulate the dynamic collimation. The reconstructed ROI images showed little errors as compared to the images reconstructed from the full-FOV scan data as well as little artifacts inside the ROI. We expect the proposed method can significantly reduce the x-ray dose in CT scans if the dynamic collimation is realized in real CT machines.

• Archives of Plastic Surgery
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• 제41권2호
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• pp.126-132
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• 2014

Background Extensive degloving injuries of the extremities usually result in necrosis of the flap, necessitating comprehensive skin grafting. Provided there is a sufficient tool to evaluate flap viability, full-thickness skin can be used from a nonviable avulsed flap. We used a Wood's lamp to determine the viability of avulsed flaps in the operation field after intravenous injection of fluorescein dye. Methods We experienced 13 cases during 16 months. Fifteen minutes after the intravenous injection of fluorescein dye, the avulsed skin flaps were examined and non-fluorescent areas were marked under Wood's lamp illumination. The marked area was defatted for full-thickness skin grafting. The fluorescent areas were sutured directly without tension. The non-fluorescent areas were covered by defatted skin. Several days later, there was soft tissue necrosis within the flap area. We measured necrotic area and revised the flap. Results Among all the cases, necrotic area was 21.3% of the total avulsed area. However, if we exclude three cases, one of a carelessly managed patient and two cases of the flaps were inappropriately applied, good results were obtained, with a necrotic area of only 8.4%. Eight patients needed split-thickness skin grafts, and heel pad reconstruction was performed with free flap. Conclusions A full-thickness skin graft from an avulsed flap is a good method for addressing aesthetic concerns without producing donor site morbidity. Fluorescein dye is a useful, simple, and cost-effective tool for evaluating flap viability. Avulsed flap injuries can be managed well with Wood's lamp illumination and a full-thickness skin graft.

• Archives of Plastic Surgery
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• 제37권6호
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• pp.795-800
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• 2010

Purpose: According to various medical publications, it is believed that epinephrine should not be injected in fingers. However numerous articles show the successful use of local anesthetic with epinephrine in the digits. Epinephrine-mixed lidocaine solution enables to maintain a bloodless field for operation and provides long duration of local anesthesia when patient was wide awake. Methods: From May 2009 to December 2009, ten patients underwent flexor tendon reconstruction with local anesthesia using epinephrine. No tourniquet was necessary. Before operation, all patients were injected with local anesthetics using 1% lidocaine 20 mL and 0.1% epinephrine 0.1 mL. Results: There was no case of digital necrosis nor gangrene in the epinephrine injection. All 10 patients actively could move the finger through a full range of motion. All procedures were performed without sedation nor tourniquet and we could obtain a good vision of operative field and patients were comfortable. The patient make his or her fingers move through a full range of active motion before the skin is closed. Phentolamine was not required to reverse the vasoconstriction in any patients. Conclusion: The assertation that epinephrine should not be injected into the fingers is clearly no longer valid. The epinephrine injection allowed the authors to adjust flexor tendon surgery without risks associated with general anesthesia. It also enables to ensure longer anesthetic duration and bloodless operative field, and prevent post operative complications. In case of flexor tendon surgery, the use of epinephrine injection is recommended because of the advantages of local anesthesia.

• Advances in concrete construction
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• 제11권5호
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• pp.375-386
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• 2021

In this paper, a study of stability and health of a newly-built railway tunnel is presented. The field test was implemented to monitor the secondary lining due to the significant cracking behaviors influenced the stability and health of the tunnel structure. Surface strain gauges were installed for monitoring the status of crack openings, and the monitoring outputs demonstrated that the cracks were still in the developing stage. Additionally, adjacent tunnel and poor condition of surrounding rock were identified as the causes of the lining cracking by systematically characterizing the crack spatial distribution, tunnel site and surrounding rock conditions. Reconstruction of partial lining and reconstruction of the whole secondary lining were designed as the maintenance projects for different cracking regions based on the construction feasibility. For assessing the health conditions of the reinforced lining, embedded strain gauges were set up to continuously measure the strain and the internal force of the reconstructed structures. For the partially reconstructed lining, the outputs show the maximum tensile elongation is 0.018 mm during 227 days, which means the structure has no obvious deformation after maintenance. The one-year monitoring of full-section was implemented in the other two completely reconstructed cross-sections by embedded strain gauge. The outputs show the reconstructed secondary lining has undertaken the pressure of surrounding rock with the time passing. According to the calculated compressive and tensile safety factors, the completely reconstructed lining has been in reliable and safe condition during the past year after reinforcement. It can conclude that the aforementioned maintenance projects can effectively ensure the stability and health of this tunnel.

• Investigative Magnetic Resonance Imaging
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• 제25권3호
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• pp.141-155
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• 2021

Purpose: To develop a 3D magnetic resonance fingerprinting (MRF) method for application in high resolution knee cartilage PD, T₁, T₂ mapping. Materials and Methods: A novel 3D acquisition trajectory with golden-angle rotating radial in k_xy direction and interleaved echo planar imaging (EPI) acquisition in the k_z direction was implemented in the MRF framework. A centric order was applied to the interleaved EPI acquisition to reduce Nyquist ghosting artifact due to field inhomogeneity. For the reconstruction, singular value decomposition (SVD) compression method was used to accelerate reconstruction time and conjugate gradient sensitivity-encoding (CG-SENSE) was performed to overcome low SNR of the high resolution data. Phantom experiments were performed to verify the proposed method. In vivo experiments were performed on 6 healthy volunteers and 2 early osteoarthritis (OA) patients. Results: In the phantom experiments, the T₁ and T₂ values of the proposed method were in good agreement with the spin-echo references. The results from the in vivo scans showed high quality proton density (PD), T₁, T₂ map with EPI echo train length (N_ETL = 4), acceleration factor in through plane (R_z = 5), and number of radial spokes (N_spk = 4). In patients, high T₂ values (50-60 ms) were seen in all transverse, sagittal, and coronal views and the damaged cartilage regions were in agreement with the hyper-intensity regions shown on conventional turbo spin-echo (TSE) images. Conclusion: The proposed 3D MRF method can acquire high resolution (0.5 mm³) quantitative maps in practical scan time (~ 7 min and 10 sec) with full coverage of the knee (FOV: 160 × 160 × 120 mm³).

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1764-1773
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• 2018

A-PET is a quad-head PET scanner developed for use in small-animal imaging. The dimensions of its volumetric field of view (FOV) are $46.1{\times}46.1{\times}46.1mm^3$ and the gap between the detector modules has been minimized in order to provide a highly sensitive system. However, such a small FOV together with the quad-head geometry causes image quality degradation. The main factor related to image degradation for the quad-head PET is the mispositioning of events caused by the penetration effect in the detector. In this paper, we propose a precise method for modelling the system at the high spatial resolution of the A-PET using a LOR (line of response) based ML-EM (maximum likelihood expectation maximization) that allows for penetration effects. The proposed system model provides the detection probability of every possible ray-path via crystal sampling methods. For the ray-path sampling, the sub-LORs are defined by connecting the sampling points of the crystal pair. We incorporate the detection probability of each sub-LOR into the model by calculating the penetration effect. For comparison, we used a standard LOR-based model and a Monte Carlo-based modeling approach, and evaluated the reconstructed images using both the National Electrical Manufacturers Association NU 4-2008 standards and the Geant4 Application for Tomographic Emission simulation toolkit (GATE). An average full width at half maximum (FWHM) at different locations of 1.77 mm and 1.79 mm are obtained using the proposed system model and standard LOR system model, which does not include penetration effects, respectively. The standard deviation of the uniform region in the NEMA image quality phantom is 2.14% for the proposed method and 14.3% for the LOR system model, indicating that the proposed model out-performs the standard LOR-based model.

• 대한두개안면성형외과학회지
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• 제11권1호
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• pp.53-57
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• 2010

연부조직만으로 경구개를 재건하는데 있어서는 환자군을 적절히 선택하는 것이 중요하며 골재건이 필요하지 않은 Okay 분류 Ia와 Ib가 주요한 적응증이 된다. 하악이나 구강저부 결손을 재건하는 것과는 다르게 경구개 결손은 구강과 비강 점막층을 동시에 수복할 수 있는 피판이 이상적이다. 이중 저자들은 전완유리피판에 전상판화 방법을 좀 더 안정적으로 시행, 경구개 전층을 성공적으로 재건하였으며, 특히 저작과 연하 등 기능적 측면뿐 아니라 경구개 및 비강의 점막을 함께 복원할 수 있는 해부학적인 장점이 있는 피판임을 확인하여 문헌고찰과 함께 보고하는 바이다.

• 한국의상디자인학회지
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• 제7권2호
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• pp.1-10
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• 2005

This study intends to examine extensively on the current situation where the full capacity of 3D CG is not being highlighted because of the lack of the information and the awareness and to look at how the virtual reality technology is being applied ranging from the design of the clothes to the marketing. A set of processes ranging from the development of the clothing design to the marketing will be performed on the web. Designers will design with 3D CG and make the patterns and will hand this over to the producer together with the virtual swatch. But there are important problems to work out. First, it is the problem of the virtual fitting room. Second, it is the absence of the 3D CG, which is easy and convenient for the clothing design. Third, it is to perfect the visual reconstruction. Fourth, it is the security of the distribution system. Fifth, it also calls for the strengthened internet network that can smooth the flow of the tremendous data. Consumer will be able to produce according to their needs and will become designer and producer at the same time, resulting in the achievement of the consumer-oriented marketing in real sense.