• Nuclear Engineering and Technology
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• v.31 no.3
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• pp.303-313
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• 1999

Various interpolation methods have been compared for reconstruction of LMR pin power distributions in hexagonal geometry. Interpolation functions are derived for several combinations of nodal quantities and various sets of basis functions, and tested against fine mesh calculations. The test results indicate that the interpolation functions based on the sixth degree polynomial are quite accurate, yielding maximum interpolation errors in power densities less than 0.5%, and maximum reconstruction errors less than 2% for driver assemblies and less than 4% for blanket assemblies. The main contribution to the total reconstruction error is made tv the nodal solution errors and the comer point flux errors. For the polynomial interpolations, the basis monomial set needs to be selected such that the highest powers of x and y are as close as possible. It is also found that polynomials higher than the seventh degree are not adequate because of the oscillatory behavior.

• Archives of Plastic Surgery
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• v.45 no.5
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• pp.441-448
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• 2018

Background Previously, surveys have been used to investigate breast reconstruction statistics. Since 2015, breast reconstruction surgery after mastectomy has been covered by the National Health Insurance Service in Korea, and data from breast reconstruction patients are now available from the Health Insurance Review and Assessment Service (HIRA). We investigated statistics in breast reconstruction in Korea through statistics provided by the HIRA Big Data Hub. Methods We investigated the number of cases in mastectomy and breast reconstruction methods from April 1, 2015 to December 31, 2016. Data were furnished by the HIRA Big Data Hub and accessed remotely online. Results were tabulated using SAS Enterprise version 6.1. Results The 31,155 mastectomy cases included 7,088 breast reconstruction cases. Implant-based methods were used in 4,702 cases, and autologous methods in 2,386. The implant-based reconstructions included 1,896 direct-to-implant and 2,806 tissue-expander (2-stage) breast reconstructions. The 2-stage tissue-expander reconstructions included 1,624 expander insertions (first stage) and 1,182 expander-to-permanent-implant exchanges (second stage). Of the autologous breast reconstructions, 705 involved latissimus dorsi muscle flaps, 498 involved pedicled transverse rectus abdominis myocutaneous (TRAM) flaps, and 1,183 involved free-tissue transfer TRAM flaps, including deep inferior epigastric perforator free-tissue transfer flaps. There were 1,707 nipple-areolar complex reconstructions, including 1,565 nipple reconstructions and 142 areola reconstructions. The 1-year mean number of breast reconstructions was 4,050. Conclusions This was the first attempt to evaluate the total number of breast reconstruction procedures using accurate, comprehensive data, and our findings may prove valuable as a foundation for future statistical studies of breast reconstruction procedures in Korea.

• Archives of Craniofacial Surgery
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• v.21 no.4
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• pp.237-243
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• 2020

Background: The scalp is an important functional and aesthetic structure that protects the cranial bone. Due to its inelastic characteristics, soft-tissue defects of the scalp make reconstruction surgery difficult. This study aims to provide an improved scalp reconstruction decision making algorithm for surgeons. Methods: This study examined patients who underwent scalp reconstruction within the last 10 years. The study evaluated several factors that surgeons use to select a given reconstruction method such as etiology, defect location, size, depth, and complications. An algorithmic approach was then suggested based on an analysis of these factors. Results: Ninety-four patients were selected in total and 98 cases, including revision surgery, were performed for scalp reconstruction. Scalp reconstruction was performed by primary closure (36.73%), skin graft (27.55%), local flap (17.34%), pedicled regional flap (15.30%), and free flap (3.06%). The ratio of primary closure to more complex procedure on loose scalps (51.11%) was significantly higher than on tight scalps (24.52%) (p=0.011). The choice of scalp reconstruction method was affected significantly by the defect size (R=0.479, p<0.001) and depth (p<0.001). There were five major complications which were three cases of flap necrosis and two cases of skin necrosis. Hematoma was the most common of the 29 minor complications reported, followed by skin necrosis. Conclusion: There are multiple factors affecting the choice of scalp reconstruction method. We suggest an algorithm based on 10 years of experience that will help surgeons establish successful surgical management for their patients.

• Archives of Plastic Surgery
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• v.48 no.6
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• pp.590-598
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• 2021

Background Although the initial projection after primary nipple reconstruction is excellent, nipple projection gradually flattens in most cases due to multiple causes. Although various methods have been reported to rebuild the nipple after nipple flattening, the most effective method of secondary nipple reconstruction remains unknown. The aim of this study was to review our institution's experiences with secondary nipple reconstruction. Methods We conducted a retrospective review from March 2012 to January 2019. We performed secondary nipple reconstruction if the primary reconstructed nipple height differed by more than 6 mm from the normal nipple height. We chose the method of nipple revision according to the degree of tissue scarring and the remaining nipple projection. Results We performed secondary nipple reconstruction on a total of 27 nipples, using purse-string sutures for 19 nipples and star flaps in eight nipples. The median follow-up period was 8 months (range, 6-19 months) after the final nipple reconstruction. Among the 19 nipples reconstructed using purse-string sutures, 10 (53%) demonstrated acceptable projection of more than 5 mm. Among the eight nipples reconstructed using star flaps, six (75%) showed acceptable projection of more than 5 mm. Most of the patients (73%) were satisfied (scores of 4 or 5) with the nipple reconstruction overall. Conclusions Few studies have presented favorable outcomes of secondary nipple reconstruction. When the star flap and purse-string suture methods were used depending on the remaining nipple height and scarring, appropriate projection could be achieved.

• Archives of Plastic Surgery
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• v.51 no.1
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• pp.52-61
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• 2024

Background Although prepectoral implant-based breast reconstruction has recently gained popularity, dual-plane reconstruction is still a better option for patients with poor-quality mastectomy skin flaps. However, shoulder morbidity is aggravated by subpectoral reconstruction, especially in irradiated patients. This study aimed to demonstrate shoulder exercise improvement in subpectoral reconstruction by delayed prepectoral conversion with an acellular dermal matrix (ADM) inlay graft technique at the time of expander-to-implant exchange after irradiation. Methods Patients with breast cancer treated for expander-to-implant exchange after subpectoral expander insertion and subsequent radiotherapy between January 2021 and June 2022 were enrolled. An ADM inlay graft was inserted between the pectoralis major muscle and the previously inserted ADM. The ADM was sutured partially overlapping the pectoralis muscle from the medial side with the transition part, to the muscle border at the lateral side. Perioperative shoulder joint active range-of-motion (ROM) for forward flexion, abduction, and external rotation was also evaluated. Results A total of 35 patients were enrolled in the study. Active shoulder ROM significantly improved from 163 degrees preoperatively to 176 degrees postoperatively in forward flexion, 153 to 175 degrees in abduction, and 69 to 84 degrees in external rotation. There was no difference in patient satisfaction regarding the final outcome between the conventional prepectoral reconstruction group and the study group. Conclusion Shoulder exercises in irradiated patients who underwent subpectoral reconstruction were improved by delayed prepectoral conversion using an ADM inlay graft. It is recommended that subpectoral reconstruction not be ruled out due to concerns regarding muscle contracture and shoulder morbidity in radiation-planned patients with poor mastectomy skin flaps.

• Archives of Plastic Surgery
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• v.50 no.6
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• pp.541-549
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• 2023

Background Despite its many advantages, prepectoral breast reconstruction also carries the risk of implant rippling. The recent introduction of partial superior implant coverage using a pectoralis muscle slip in prepectoral direct-to-implant (DTI) breast reconstruction has shown the potential to minimize upper pole rippling. The purpose of this study was to identify factors associated with rippling and the effectiveness of our surgical technique. Methods In total, 156 patients (186 breasts) who underwent prepectoral DTI breast reconstruction between August 2019 and March 2021 were identified retrospectively. Patient data were analyzed from medical records. Univariable and multivariable logistic analyses were performed to contextualize the risks associated with rippling deformity relative to demographic characteristics and other clinical factors. Retrospective propensity-matched analysis was performed to identify the relationship between rippling deformity and the reconstruction method. Results Patients with body mass index (BMI; odds ratio [OR], 0.736; p < 0.001), those with a postoperative chemotherapy history (OR, 0.324; p = 0.027) and those who received breast reconstruction via the superior coverage technique (OR, 0.2; p = 0.004), were less likely to develop rippling deformity. The median follow-up period was 64.9 weeks, and there were no significant differences between patients in types of mastectomy, implant, or acellular dermal matrix. Patients who underwent superior coverage technique-based reconstruction showed significantly reduced rippling (OR, 0.083; p = 0.017) Conclusion Patients with higher BMI and prior postoperative chemotherapy were less likely to develop rippling deformity. The superior coverage technique can be effective in minimizing upper pole rippling.

• Journal of IKEEE
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• v.20 no.2
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• pp.152-162
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• 2016

Electrical resistivity tomography (ERT) is a technique to reconstruct the internal resistivity distribution using the measured voltages on the surface electrodes. ERT inverse problem suffers from ill-posedness nature, so regularization methods are used to mitigate ill-posedness. The reconstruction performance varies depending on the type of regularization method. In this paper, an interacting dual-mode regularization method is proposed with two different regularization methods, L1-norm regularization and total variation (TV) regularization, to achieve robust reconstruction performance. The interacting dual-mode regularization method selects the suitable regularization method and combines the regularization methods based on computed mode probabilities depending on the actual conditions. The proposed method is tested with numerical simulations and the results demonstrate an improved reconstruction performance.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.237-244
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• 2006

We produced the electron density distribution in the ionosphere over South Korea using the data from nine permanent GPS (Global Positioning System) stations which have been operated by KASI (Korea Astronomy and Space Science Institute). The dual-frequency GPS receiver data was used to precisely estimate the electron density in the ionosphere and we obtained the precise electron density profile based on two-dimensional TEC (Total Electron Contents). We applied ART (Algebraic Reconstruction Technique), which is one of the most commonly used algorithms to develop the tomography model. This paper presented the electron density distribution over South Korea with time. We compared with the electron density profiles derived from the GPS tomography reconstruction, Ionosonde measurement data obtained by observations, and the IRI-2001 values. As a result, the electron density profile by GPS reconstruction was in excellent agreement with the electron density profile obtained by Ionosonde measurement data.

• Archives of Plastic Surgery
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• v.40 no.2
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• pp.117-122
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• 2013

Background Latissimus dorsi (LD) myocutaneous flap is a popular method of breast reconstruction which can be associated with high incidence of seroma formation. Quilting sutures at the harvest site are used to reduce this. Barbed sutures are self anchoring sutures which avoid multiple knotting and can be useful in quilting. Methods A retrospective analysis of prospectively maintained database of patients who underwent LD flap breast reconstruction between January 2009 and January 2011 was carried out. Seroma formation at the harvest site, wound related complications, inpatient stay and duration of surgery were analysed and a comparison was made between two groups where quilting was done with barbed (V-Loc) suture and conventional polydioxanone (PDS) II sutures. Results Fifty-seven patients were included of which 33 had quilting by V-Loc sutures and in 24 patients PDS II suture was used. Median age in the PDS group was 55 years (interquartile range [IQR)], 45 to 61 years) which was comparable to the V-Loc group (53 years [IQR, 48 to 59 years]; P-value 0.948). Sixteen patients (28%) had significant seroma formation and 5 (9%) patients developed superficial wound dehiscence. Incidences of seroma or wound complications were comparable (P-value 0.378 and 1.00, respectively). Secondary outcomes such as total duration of surgery, total inpatient stay, total amount of drain at the donor site were also similar in two groups. Conclusions Use of barbed sutures for quilting the donor site in LD flap reconstruction is a feasible option and the associated seroma formation and wound complications are comparable with conventional sutures.

• Korean Journal of Bronchoesophagology
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• v.9 no.2
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• pp.69-73
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• 2003

Various flaps are using for reconstruction of esophageal defect. The choice of reconstruction is depended to the oncologic needs of the situation. If the entire esophagus or significant part of the thoracic esophagus is involved by tumor, then total esophagectomy and gastric pull-up or colon transposition is indicated. But for most hypopharyngeal tumors, laryngopharyngeal tumors, and cervical esophageal tumors, segmental resection of these area and replacement with a jejunal fee or forearm free flap has become the standard technique. The authors have experienced a case of total pharyngo-laryngo-esophago-gastrectomy and colon transposition in a patient of esophageal cancer following partial esophagectomy and gastic pull-up due to corrosive esophageal stricture. We report this case with brief review of the literatures.