• Microbiology and Biotechnology Letters
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• v.39 no.4
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• pp.364-373
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• 2011

Human embryonic stem cells have been highlighted as a valuable cellular source in the regenerative medicine field, due to their pluripotency. However, there is the challenge of the establishment of specific functional cell type forms of undifferentiated human embryonic stem cells (hESC). To establish and purify functional cell types from hESCs, we differentiated undifferentiated hESCs into vascular lineage cells and sorted the specific cell population from the whole cell population, depending on their cell volume, and compared them with the non-sorted cell population. We observed that about 10% of the PECAM positive population existed in the VEGF induced differentiating human embryoid body (hEB), and differentiated hEBs were made into single cells for cell transplantation. After making single cells, we performed cell sorting using a fluorescence-activated cell sorter (FACs), according to their cell volume on the basis of FSC region gating, and compared their therapeutic capacity with the non-sorted cell population through cell transplantation into hindlimb ischemic disease model mice. 4 Weeks after cell transplantation, the recovery rate of blood perfusion reached 54% and 17% in the FSC regions of sorted cells- and non-sorted cells, respectively. This result suggests that derivation of a functional cell population from hESCs can be performed through cell sorting on the basis of cell volume after preliminary differentiation induction. This approach may then greatly contribute to overcoming the limitations of marker sorting.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.60-70
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• 2011

Conventional content management systems are independently developed for a specific field in general. Therefore usage of contents for the CMS will be limited to the corresponding CMS field. These characteristics might reveal a defect that CMS could not support effectively in exchange and sharing of information between CMSs. On the other hand, metadata standardization shows big differences in method and representation for the fields of CMS because all metadata standardizations are variously performed according to applications of them. There are lots differences that make interoperability between CMSs impossible. In this paper, we propose a novel metadata schema based on METS(metadata encoding and transmission standard) so that metadata standardization can be fulfilled in reality and solved the problem of duplicated contents created from different CMSs. This framework of integrated metadata proposed here can offer an interoperability between contents created by different CMSs, and discard duplicated contents. As a result of the proposed technology, we obtain 0.5% duplication rate from traditional 10.3%. In addition the filtering ability of duplicated contents shows from 92% to 96%, which proves the effectiveness and stability of the proposed technology.

• Korean Journal of Optics and Photonics
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• v.23 no.2
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• pp.64-70
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• 2012

We analyzed the changes in electrical and optical characteristics of 1 $mm^2$ multiple-quantum-well (MQW) blue LEDs grown on a c-plane sapphire substrate after a stress test. Experiments were performed by injecting 50 mA current for 200 hours to TO-CAN packaged sample chips. We selected the value of injection current for stress through the junction-temperature measurement by using the forward-voltage characteristics of a diode to maintain a sufficiently low junction temperature during the test. The junction temperature at the selected injection current of 50 mA was 308 K. Experiments were performed under the assumption that the average junction temperature of 308 K did not affect the characteristics of the ohmic contact and the GaN-based materials. Before and after the stress test, we measured and analyzed current-voltage, light-current, light distribution on the LED surface, wavelength spectrum and relative external quantum efficiency (EQE). After the stress test, it was observed experimentally that the optical power and the relative EQE decreased. We theoretically investigated and experimentally proved that these phenomena are due to the increased nonradiative recombination rate caused by the increased defect density.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.2
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• pp.154-165
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• 2006

Objectives : It is difficult to place implants at a severely atrophied edentulous mandible because of vertical and horizontal alveolar defect. The autogenous and allogenic bone graft and guided bone regeneration are useful, but there are some limitations such as the resorption and infection of the grafted bone, and insufficiency of soft tissue. Distraction osteogenesis has recently evolved a challenging technique to overcome major draws of conventional augmentation procedures, we, therefore, report the four applications of implant placement after vertical alveolar distraction osteogenesis. Patients and Methods : Four patients(all female, mean age: $60{\pm}6$ years) with severe alveolar ridge deficiencies at their anterior mandible were treated with vertical alveolar distraction osteogenesis by intraoral device(Track 1.5, 15 mm model, KLS Martin, Tuttlingen, Germany) and placement of implants (Branemark MK III, TiUnite). After the latency periods of 5, 7, 8 days, distraction rhythm and rate were $0.5\;mm{\times}2\;times/day$ in the case of good bone quality, and $0.25\;mm{\times}3\;times/day$ in the case of poor bone quality. After consolidation periods of mean fifteen weeks, five implants for each patients were placed at the interforaminal area. Results : On average, a vertical gain of $11.38{\pm}1.38\;mm$ was obtained by distraction. And all distraction zone showed complete ossification by panoramic radiography. There were no postoperative complications other than numbness of lower lip in one case. Total twenty implants in four patients were placed and their outcomes were satisfactory. Conclusion : It is a useful method to place five implants after vertical distraction osteogenesis of the severely atrophied mandible for the implant-supported fixed prosthesis.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.4
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• pp.306-312
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• 2010

Purpose: The purpose of this experiment was to evaluate the clinical effect of cultured autoglogous osteoblasts as a way to treat the defect of mandible in rabbits. Materials and Methods: Twelve rabbits were used to determine the rate of osteogenesis. The osteoblasts were obtained from the iliac crest of rabbits using aspiration. They were then cultured in Dulbecco's Modified Eagles's Medium (DMEM) with beta-glycerophosophatate, L-ascorbicacid, and dexamethasone to proliferate and differentiate osteoprogenitor cells. The expression of osteogenic markers were detected by reverse transcription-polymerase chain reaction (RT-PCR) and silver nitrate staining techniques. Five, 10-mm holes were placed in each rabbit mandible to simulate defective regions with the use of a low speed trephine bur. In the experimental group, the previously cited defects were grafted with both activated osteoblastic and autogenous bone. The control group, however, was only grafted with autogenous bone. Both groups were then analyzed at 2, 4, and 8-week intervals using bone histomorphometric analysis. Results: According to histomorphologic analysis, the rates of new bone formation at the 2, 4, and 8-week intervals were 36%, 51%, and 23% for the control group, respectively; 52%, 39%, and 28%, for the experimental group, respectively. The experimental group showed higher rates of new bone formation compared to the control group at both the 2-week and 8-week interval. Conclusion: Bone marrow-derived osteoblasts seems to be a promising bone graft material.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.4
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• pp.313-323
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• 2010

Purpose: This study was conducted to evaluate the effect of beta-tricalcium phosphate (Cerasorb$^{(R)}$, Germany) and deproteinized bovine bone (Bio-Oss$^{(R)}$, Switzerland) grafted to the defect of rat calvaria artificially created and the effect of use of absorbable membrane (BioMesh$^{(R)}$, Korea) on new bone formation. Materials and Methods: Transosseous circular calvarial defects with diameters of 5 mm were prepared in the both parietal bone of 30 rats. In the control group I, no specific treatment was done on the defects. In the control group II, the defects were covered with absorbable membrane. In the experimental group I, deproteinized bovine bone was grafted without absorbable membrane; in the experimental group II, deproteinized bovine bone was grafted with absorbable membrane; in the experimental group III, beta-tricalcium phosphate was grafted without absorbable membrane; in the experimental group IV, beta-tricalcium phosphate was grafted with absorbable membrane. The animals were sacrificed after 3 weeks and 6 weeks respectively, and histologic and histomorphometric evaluations were performed. Results: Compare to the control groups, the experimental groups showed more newly formed bone. Between the experimental groups, beta-tricalcium phosphate showed more resorption than deproteinized bovine bone. Stabilization of grafted material and interception of the soft tissue invasion was observed in the specimen treated with membrane. There was no statistical difference between the experimental group I, III and experimental group II, IV classified by graft material, but statistically significant increase in the amount of newly formed bone was observed in the experimental group I, II and II, IV classified by the use of membrane (P<0.05). Conclusion: Both beta-tricalcium phosphate and deproteinized bovine bone showed similar osteoconductibility, but beta-tricalcium phosphate is thought to be closer to ideal synthetic graft material because it showed higher resorption rate in vivo. Increased new bone formation can be expected in bone graft with use of membrane.

• Archives of Craniofacial Surgery
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• v.17 no.3
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• pp.128-134
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• 2016

Background: Blowout fracture is one of the most common facial fractures, and patients usually present with accompanying ocular complications. Many studies have looked into the frequency of persistent ocular symptoms, but there is no study on assault patients and related ocular symptoms. We evaluated the incidence of residual ocular symptoms in blowout fractures between assaulted and non-assaulted patients, and sought to identify any connection among the degree of enophthalmos, defect size, and assault-related injury. Methods: A retrospective review was performed for any patient who sustained a unilateral blowout fracture between January 2010 to December 2014. The collected data included information such as age, gender, etiology, and clinical ocular symptoms as examined by an ophthalmologist. This data was analyzed between patients who were injured through physical altercation and patients who were injured through other means. Results: The review identified a total of 182 patients. Out of these, 74 patients (40.7%) have been struck by a fist, whereas 108 patients (59.3%) have sustained non-assault related injuries. The average age was 36.1 years, and there was a male predominance in both groups (70 patients [94.6%] in the assaulted group and 87 patients [80.6%] in the non-assault group). Diplopia and enophthalmos were more frequent in patients with assault history than in non-assaulted patients (p<0.05). Preoperatively, 25 patients (33.8%) with assault history showed diplopia, whereas 20 patients (18.5%) showed diplopia in the non-assaulted group (p<0.05). Preoperative enophthalmos was present in 34 patients (45.9%) with assault history, whereas 31 patients (28.7%) showed enophthalmos in the non-assaulted group (p<0.05). Conclusion: Patients with an assault history due to a fist blow experienced preoperative symptoms more frequently than did patients with non-assault-related trauma history. Preoperative diplopia and enophthalmos occurred at a higher rate for patients who were assaulted. Surgeons should take into account such characteristics in the management of assaulted patients.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.14-21
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• 2011

A unit modular system is a construction method which installs on site by manufacturing 50%~90% of the whole process in the factory. This method can minimize the process in the site and maximize the operation, which will reduce the duration and improve the overall quality. The recent paradigm of construction is to be sustainable building. Modular system can be regarded as a sustainable building construction method because it can reduce the amount of construction waste by recycling partial or whole part of overdue building be torn down. A unit modular system is the answer to cope with the increasing market of small size housings. A unit modular system is the most appropriate option at this point. This research proposes the standard operation and construction process of modular system, which enable to optimal system. A case study of reconstructing small-size housing was introduced to support this proposal. Finished unit modular is the reasonable way. However, 80% of complication rate of the modular is the most rational when a defect occurrence during delivery is considered.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.6
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• pp.25-31
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• 2004

In this paper, we introduce kinetic Monte Carlo (kMC) methods for simulating diffusion process in nano-scale device fabrication. At first, we review kMC theory and backgrounds and give a simple point defect diffusion process modeling in thermal annealing after ion (electron) implantation into Si crystalline substrate to help understand kinetic Monte Carlo methods. kMC is a kind of Monte Carlo but can simulate time evolution of diffusion process through Poisson probabilistic process. In kMC diffusion process, instead of. solving differential reaction-diffusion equations via conventional finite difference or element methods, it is based on a series of chemical reaction (between atoms and/or defects) or diffusion events according to event rates of all possible events. Every event has its own event rate and time evolution of semiconductor diffusion process is directly simulated. Those event rates can be derived either directly from molecular dynamics (MD) or first-principles (ab-initio) calculations, or from experimental data.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.4
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• pp.219-225
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• 2003

Purpose: Platelet Rich Plasma(PRP) application is increasing with sinus inlay bone graft, but there is few research with radiographic ananlysis on effect of PRP in maxillary sinus. The author investigated the amount of bony changes of maxillary sinus for dental implantation among the patients with maxillary inlay graft. Materials and Methods: With 10 patients who were treated with sinus inlay autologous bone grafting combined with PRP technique, and with 5 patients who were treated with sinus inlay grafting only without PRP, the panoramic radiographys which were taken at preoperation, immediate postoperation, 3months postoperation, and 4 months postoperation(a month after dental implantation)periods were analysed. The films had been scanned, and then proceeded throughout image analysis system. The bone density of maxillary grafted sites was compared with adjacent tooth enamel density and remeasured according to density luminosity of each film. The density changes on PRP group and bone graft only group were analysed with non-parameteric statistics method. Results: In PRP combined patients group, bone density on postoperation periods was increased totally. The remarkable enhanced change of bone density was observed on 3 months postoperation period, thereafter the increasing rate was slightly reduced. In only bone graft patients group, bone density on postoperation periods was also increased compared with preoperation period, but the bone density of 4 months postoperation period was decreased compared with 3 months postoperation period. The amount of bone density on PRP group was significantly changed according to periods in contrast to bone graft only group. Conclusion: The bone density on PRP group was remarkably increased at 3 months postoperation compared to bone graft only group and it was seemed to be associated with more new bone formation, less grafted bone resorption at bone grafted sites with PRP.