• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.89-93
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• 2017

GaN single crystals were grown by controlling of various processing parameters such as growing temperature, V/III ratio and growing rate. We optimized thickness of bulk GaN single crystal by analyzing defect of surface and inside of the GaN single crystal for application to high brightness and power device. 2-inch bulk GaN single crystals were grown by HVPE (hydride vapor phase epitaxy) on sapphire and their thickness was 0.3~7.0 mm. Crystal structure of the grown bulk GaN was analyzed by XRD (X-ray diffraction). The surface characteristics of the grown bulk GaN were observed by OM (optical microscope) and SEM (scanning electron microscopy) with measuring EPD (etch pits density) of the GaN crystals.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.4
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• pp.348-355
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• 2006

Tennison was the first to recognize and to preserve the Cupid's bow by lowering the peak in the margin of the cleft. Randall had modified the Tennison's repair based on accurate measurements. Bardach's technique evolved from the basic concept of triangular flap cleft lip repair described by Tennison-Randall method. Precise measurements are used to define the dimensions of the equilateral triangular flap, which is created on the cleft side and is inserted into an equilateral triangular defect on the noncleft side. Two symmetrical vertical distances on either side of the cleft are thus formed. It is essential that the incisions in the skin correspond precisely with those on the muscles and mucosa, and that all layers are sutured with the use of the triangular flap, thus preventing vertical scar contracture. This procedure produces a symmetric, balance lip with a well-defined Cupid's bow, a symmetric vermilion, and a properly aligned orbicularis oris muscle. We had treated three patients with unilateral incomplete cleft lip by using Bardach's triangular flap method. The operation scars could be reduced comparing to Millard method because Bardach's method did not use the columella base and the alar base incision. And the flap design was more simple and accurate comparing to Tennison-Randall method. On the other hand, the postoperative scars on the philtrum pointed as a disadvantage of triangular flap method were cosmetically acceptable because the three patients had incomplete cleft lip. We have experienced that Bardach's triangular flap is a recommendable technique for the repair of unilateral incomplete cleft lip.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.447-453
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• 2010

The hemifacial microsomia is characterized by variable underdevelopment of the craniofacial skeleton, external ear, and facial soft tissues. So, patients with hemifacial microsomia have an occlusal plane canting and malocclusion with facial asymmetry. Distraction osteogenesis (DO) with an intraoral or extraoral device is a technique using tension to generate new bone with gradual bone movement and remodeling. DO has especially been used to correct craniofacial deformities such as a hemifacial microsomia, facial asymmetry, and mandible defect that could not adequately be treated by conventional reconstruction with osteotomies. It has a significant advantage to lengthen soft and hard tissue of underdeveloped site without bone graft and a few complication such as nerve injury or muscle contracture. A 13-years old girl visited our clinic for the chief complaint of facial asymmetry. She had a left hypoplastic maxilla and mandible, occlusal plane canting and malocclusion. We diagnosed hemifacial microsomia and lanned DO to lengthen the affected side. Le Fort I osteotomy, left mandibular ramus and symphysis osteotomy were performed. The internal distraction devices fixed with screw on maxillary and mandibular ramus osteotomy sites. External devices were adapted to lower jaw for DO on symphysis osteotomy site and to upper jaw for rapid maxillary expansion (RME). At 7days after surgery, distraction was started at the rate of 1mm per day for 13days, and after 4months consolidation periods, distraction devices were removed. Simultaneous multiple maxillo-mandibular distraction osteogenesis with RME resulted in a satisfactory success in correcting facial asymmetry as well as occlusal plane canting for our hemifacial microsomia.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.16.1-16.9
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• 2016

Background: The association of biomaterial combined with repair factor-like platelet-rich plasma (PRP) has prospective values. Bovine-derived xenograft has been identified as an osteoconductive and biocompatible grafting material that provides osseointegration ability. PRP has become a valuable adjunctive agent to promote healing in a lot of dental and oral surgery procedures. However, there are controversies with respect to the regenerative capacity of PRP and the real benefits of its use in bone grafts. The purpose of this study was to assess the influence of PRP combined with xenograft for the repair of peri-implant bone defects. Methods: Twelve rabbits were used in this study, and the experimental surgery with implant installation was performed simultaneously. Autologous PRP was prepared before the surgical procedure. An intrabony defect (7.0 mm in diameter and 3.0 mm deep) was created in the tibia of each rabbit; then, 24 titanium dental implants (3.0 mm in diameter and 8.5 mm long) were inserted into these osteotomy sites. Thus, a standardized gap (4.0 mm) was established between the surrounding bony walls and the implant surface. The gaps were treated with either xenograft alone (control group) or xenograft combined with PRP (experimental group). After healing for 1, 2, 3, 4, 5, and 6 weeks, the rabbits were sacrificed with an overdose of KCl solution. Two rabbits were killed at each time, and the samples including dental implants and surrounding bone were collected and processed for histological analysis. Results: More newly formed bone and a better bone healing process were observed in control group. The histomorphometric analysis revealed that the mean percentage of bone-to-implant contact in the control group was significantly higher than that of the experimental group (25.23 vs. 8.16 %; P < 0.05, independent-simple t test, analysis of variance [ANOVA]). Conclusions: The results indicate that in the addition of PRP to bovine-derived xenograft in the repair of bone defects around the implant, PRP may delay peri-implant bone healing.

• Journal of Korean Foot and Ankle Society
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• v.11 no.2
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• pp.177-181
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• 2007

Purpose: The purpose of this study is to compare the two prosthesis that used for total ankle arthroplasty. Materials and Methods: From Sept. 2003 to Jun 2006, 13 patients and 14 ankles that could be follow up more than 1 months. Semiconstrained type (Group I, 7 cases) and Unconstrained type (Group II, 7 cases) were used for total ankle arthroplasty. Mean age was 63.2 year-old, 12 ankles are men and 2 ankles were women. Mean follow up periods were 29 months. The criteria to compare the clinical result were postoperative range of motion, AOFAS score and residual bone stock of medial malleolus. Results: Postoperative range of motion of group I was $43.6{\pm}9.4$ degrees and of group II was $50.7{\pm}7.3$ degrees (p=0.115). Postoperative AOFAS score of group I was $77.1{\pm}13.0$ points and of group II was $86.0{\pm}5.7$ points (p=0.094). Resected bone stock in medial malleolus of group I was $10.7{\pm}2.5\;mm$ and of group II was $5.1{\pm}1.2\;mm$ (p=0.003). Total number of complication in our study was 9 cases. 3 cases were a malleolar fracture, two occurred at intra-operation, the other at follow-up period. Re-operation was done in 6 cases, 3 cases were calcaneal corrective osteotomy, 2 cases were resection of a heterotopic bone and one case was pedicular flap operation for skin problem. Conclusion: In our hospital, mobile bearing type prosthesis shows good result than a semiconstrained type in respect of residual bone stock in medial malleolus. Postoperative range of motion and AOFAS score between two groups shows no significant difference. But small number of patients and short term follow up period is a defect in our study, afterward more population and long term follow up period are needed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.255-264
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• 2014

This study analyzes the cause and the repairing method of water leak by parts of basement parking lot which is recorded to have a high defect frequency in apartment buildings. It has been assessed that the cause of water leakage on the first floor upper substrate is due to such factors as landscaping and weights. During construction or through other cases, it has been determined that cracks were produced in the apartment structure because the structure was weak and exposed to the effects of the substrate movement. The base floor and underground external walls are areas that are exposed to water pressure (uplife pressure), thus in normal cases the rear surface repair of the structure using sythetic rubberized polymer gel should be considered as an effective method. However, in cases where application of waterproofing layer is required in the structure due to high water pressure, using asystolic cement milk grout to form the waterproofing layer and applying water-swelling acrylic material into the cracked areas is considered to be highly effective.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.1
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• pp.1-16
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• 2004

The use of artificial nerve conduit containing viable Schwann cells is one of the most promising strategies to repair the peripheral nerve injury. To fabricate an effective nerve conduit whose microstructure and internal environment are more favorable in the nerve regeneration than existing ones, a new three-dimensional Schwann cell culture technique using $Matrigel^{(R)}$. and dorsal root ganglion (DRG) was developed. Nerve conduit of three-dimensionally arranged Schwann cells was fabricated using direct seeding of freshly harvested DRG into a $Matrigel^{(R)}$ filled silicone tube (I.D. 1.98 mm, 14 mm length) and in vitro rafting culture for 2 weeks. The nerve regeneration efficacy of three-dimensionally cultured Schwann cell conduit (3D conduit group, n=6) was assessed using SD rat sciatic nerve defect of 10 mm, and compared with that of silicone conduit filled with $Matrigel^{(R)}$ and Schwann cells prepared from the conventional plain culture method (2D conduit group, n=6). After 12 weeks, sciatic function was evaluated with sciatic function index (SFI) and gait analysis, and histomorphology of nerve conduit and the innervated tissues of sciatic nerve were examined using image analyzer and electromicroscopic methods. The SFI and ankle stance angle (ASA) in the functional evaluation were $-60.1{\pm}13.9$, $37.9^{\circ}{\pm}5.4^{\circ}$ in 3D conduit group (n=5) and $-87.0{\pm}12.9$, $32.2^{\circ}{\pm}4.8^{\circ}$ in 2D conduit group (n=4), respectively. And the myelinated axon was $44.91%{\pm}0.13%$ in 3D conduit group and $13.05%{\pm}1.95%$ in 2D conduit group to the sham group. In the TEM study, 3D conduit group showed more abundant myelinated nerve fibers with well organized and thickened extracellular collagen than 2D conduit group, and gastrocnemius muscle and biceps femoris tendon in 3D conduit group were less atrophied and showed decreased fibrosis with less fatty infiltration than 2D conduit group. In conclusion, new three-dimensional Schwann cell culture technique was established, and nerve conduit fabricated using this technique showed much improved nerve regeneration capacity than the silicone tube filled with $Matrigel^{(R)}$ and Schwann cells prepared from the conventional plain culture method.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.6
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• pp.460-465
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• 2010

Introduction: A cleft palate is a common birth defect in humans with an incidence of 1/500 to 1/1,000 births. It appears to be caused by multiple genetic and environmental factors during palatogenesis. Many molecules are involved in palate formation but the biological mechanisms underlying the normal palate formation and cleft palate are unclear. Accumulating evidence suggests that transforming growth factor $\beta$/bone morphogenetic proteins (TGF-$\beta$/BMP) family members mediate the epithelial-mesenchymal interactions during palate formation. However, their roles in palatal morphogenesis are not completely understood. Materials and Methods: To understand the roles of TGF-$\beta$/BMP signaling in vivo during palatogenesis, mice with a palatal mesenchyme- specific deletion of Smad4, a key intracellular mediator of TGF-$\beta$/BMP signaling, were generated and analyzed using the Osr2Ires-Cre mice. Results: The mutant mice were alive at the time of birth with open eyelids and complete cleft palate but died within 24 hours after birth. In skeletal preparation, the horizontal processes of the palatine bones in mutants were not formed and resulted in a complete cleft palate. At E13.5, the palatal shelves of the mutants were growing as normally as those of theirwild type littermates. However, the palatal shelves of the mutants were not elevated at E14.5 in contrast to the elevated palatal shelves of the wild type mice. At E15.5, the palatal shelves of the mutants were elevated over the tongue but did not come in contact with each other, resulting in a cleft palate. Conclusion: These results suggest that mesenchymal Smad4 mediated signaling is essential for the growth of palatal processes and suggests that TGF-$\beta$/BMP family members are essential regulators during palate development.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.353-359
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• 2010

Introduction: This study examined the effect of cyclosporine A (CsA) on the allogenic cranial bone graft in the mice. Materials and Methods: Twenty eight 12-week-old male ICR mice weighing 40 g were used. The experimental group was injected subcutaneously with CsA (10 mg/kg/day) diluted in Caster oil for 7 days prior to the graft until sacrifice. The control group was injected with the same solution without CsA. Two full-thickness bone defects with a diameter of 3 mm were made with a trephine bur in the parietal bone lateral to the sagittal suture. A calvarial defect of a mouse was grafted with allogenic calvarial bone disc from another mouse. The experimental and control groups were injected with CsA and the solution without CsA in the same manner before surgery, respectively. The mice were sacrificed at 1 week, 2 weeks and 4 weeks after the bone graft, respectively. Results: In the experimental group, fibrous connective tissues and small amounts of inflammatory cells were observed. At 2 weeks after the allograft in the experimental group, new bone formation in fibrous collagenous tissue and around the allogenic bone was noted. At 4 weeks after the allograft, new bone formation was active along and at the periphery of the mature allogenic bone. The proliferation of blood vessels increased in bone marrow. In the control group, fibrous tissues and inflammatory cells were observed around the allogenic bone and existing bone at 1 week. At 2 weeks after the allograft, the proliferation of blood vessels accompanied by inflammatory cells were scattered in the fibrous connective tissues. New bone formation around the allogenic and existing bone could be observed. At 4 weeks after the allograft, inflammatory cells were severely infiltrated around the allogenic bone. Osteoclasts were scattered along the allogenic bone and induced bone resorption. Conclusion: These results suggest that the daily administration of CsA (10 mg/kg/day) induces efficient immunosuppression without serious complications, and this protocol might be useful for the experimental model of allogenic bone grafts.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.505-527
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• 2000

The 3 beagle dogs aged over one and half years and weighed 14 to 16 Kg were utilized in this study. Horizontal furcation defects were induced around 3rd, and 4th premolars bilaterally. BMP-4 in conjunction with EGF and BMP-4 only were applied in the right and left premolars respectively. 1 animal was sacrificed at 2nd week, 4th week, and 8th week, after regenerative surgery respectively. Semi-thin sections using glass-knife were stained with hematoxylin- eosin and trichrome for light microscopic study. The results were as follows : 1 . The long junctional epithelial downgrowth was observed in both area applied with BMP-4 and with BMP-4 and EGF at 2nd week after the surgery. 2 . The extensive regeneration of new bone and cementum was appeared at 4th week and the maturation of bone was observed at 8th week in both area applied with BMP-4 and with BMP-4 and EGF. 3 . The root ankylosis and resorption was presented along the exposed root surface at the coronal 1/3 of defect in the BMP-4 applied site, but it was not shown in the site applied with BMP-4 in conjunction with EGF at the 4th week. At 8th week, the root ankylosis was apparently appeared in the BMP-4 and EGF applied site as well as in the BMP-4 applied site. 4 . The periodontal ligament tissue including Sharpey's fiber inserted into cementum and alveolar bone, was formed along the exposed root surface in the area applied with BMP-4 only, but in the site applied with BMP-4 and EGF, the collagen fiber running parallel to the root surface without Sharpey's fiber, was observed in the periodontal ligament space at 4th and 8th week. Within the above results, BMP-4 had the remarkable capability to regenerate the periodontal tissue and EGF had possibility to prevent from the root ankylosis. Therefore, growth factors including BMP-4 and EGF may have the strong possibility to be utilized in the clinical periodontal treatments.