• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.4
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• pp.340-349
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• 2007

Free flap transplantation with microvascular anastomosis has been successfully performed by development of surgical technique, materials and postoperative monitoring equipments of flap. But success rate of microvascular anastomosis is influenced by various factors, and failure rate is about 5-10%. The most influential factor for success rate is surgical technique and other factors that influence failure of microvascular anastomosis are ischemic time of free flap, thrombus formation of anastomosis region and vascular spasm. In this study, vascular patency and thrombus formation in experimental micro-venous anastomosis, and endothelial repair were observed with histologic analysis, scanning electron microscopy, transmission electron microscopic examination. The results were obtained as follows: 1. In vascular patency test in 30 minute and 7 days after micro-venous anastomosis with heparin irrigation, all of 12 anastomosis site were good vascular patency. 2. In thrombus formation in 2 weeks group(Experimental I), 2 site of 6 cases were observed thrombus, and in 4 weeks group(Experimental II), 1 site of 6 cases were observed thrombus. 3. In histologic examination, normal vein(Control Group) showed continued internal elastic lamina, well formed thick smooth muscle layer and connective tissue. The group of 2 weeks after microvenous anastomosis(Experimental I) showd locally recovered internal lamina, discontinued internal lamina, disorganized smooth muscle cells and granulation tissue around suture silk. In the group of 4 weeks after micro-venous anastomosis(Experimental II), anastomosis site showed almostly continued internal lamina, disorganized smooth muscle cells and cicartrized tissue around suture silk. 4. In scanning electron microscope examination in 2 weeks(Experimental I) after micro-venous anastomosis, mesh fibrin formation showed near to endothelial cells, and in 4 weeks after micro-venous anastomosis(EXperimental II), numerous blood cells and fibrin mesh formation was seen associated with irregular endothelial cell arrangement. 5. In transmission electron microscope examination in 2 weeks after micro-venous anastomosis(Experimental I), irregular arrangement of smooth muscle cells was seen adjacent to collagenized tissue around suture silk. In 4 weeks after micro-venous anastomosis(Experimental II), denuded venous wall composed of relatively well arranged smooth muscle cells was covered by endothelial cells, but fibroblast cells and foreign body giant cells near to suture silk was remained. From the results obtained in this study, results of good vascular patiency and anti-thrombotic effect of heparin were obtained as a local irrigation solution, and repair of venous endothelial cell was observed in 2 weeks after micro-venous anastomosis.

• Steel and Composite Structures
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• v.19 no.5
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• pp.1221-1236
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• 2015

Since the coefficients of thermal expansion (CTE) between concrete and GFRP, steel and GFRP are quite different, GFRP laminates with different laminas stacking-sequence present different thermal behavior and currently there is no specification on mechanical properties of GFRP laminates, it is necessary to investigate the thermal influence on composite girder with stay-in-place (SIP) bridge deck at different levels and on different scales. This paper experimentally and theoretically investigated the CTE of GFRP at lamina's and laminate's level on micro-mechanics scales. The theoretical CTE values of laminas and laminates agreed well with test results, indicating that designers could obtain thermal properties of GFRP laminates with different lamina stacking-sequence through micro-mechanics methods. On the basis of the CTE tests and theoretical analysis, the thermal behaviors of composite girder with hybrid GFRP-concrete deck were studied numerically and theoretically on macro-mechanics scales. The theoretical results of concrete and steel components of composite girder agreed well with FE results, but the theoretical results of GFRP profiles were slightly larger than FE and tended to be conservative at a safety level.

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.604-604
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• 2007

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• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.410-420
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• 2016

The geometric dimension and shape of microchannels that are formed during surface texturing are widely studied for applications in flow control, and drag and friction reduction. In this research, a new method for controlling the deformation of U channels during micro-rolling-based surface texturing was developed. Since the width of the U channels is almost constant, controlling the depth is essential. A calibration procedure of initial rolling gap, and proportional-integral PI controllers and a linear interpolation have been applied simultaneously to control the depth. The PI controllers drive the position of the pre-U grooved roll as well as the rolling gap. The relationship between the channel depth and rolling gap is linearized to create a feedback signal in the depth control system. The depth of micro channels is studied on A2021 aluminum lamina surfaces. Overall, the experimental results demonstrated the feasibility of the method for controlling the depth of microchannels.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.531-536
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• 2013

This paper investigates the effect of prolonged high temperature exposure on concentric laminated $Al_2O_3-ZrO_2$ composites. An ultrafine scale microstructure with a cellular 7 layer concentric lamination with unidirectional alignment was fabricated by a multi-pass extrusion method. Each laminate in the microstructure was $2-3{\mu}m$ thick. An alternate lamina was composed of 75%$Al_2O_3$-(25%m-$ZrO_2$) and t-$ZrO_2$ ceramics. The composite was sintered at $1500^{\circ}C$ and subjected to $1450^{\circ}C$ temperature for 24 hours to 72 hours. We investigated the effect of long time high temperature exposure on the generation of residual stress and grain growth and their effect on the overall stability of the composites. The residual stress development and its subsequent effect on the microstructure with the edge cracking behavior mechanism were investigated. The residual stress in the concentric laminated microstructure causes extensive micro cracks in the t-$ZrO_2$ layer, despite the very thin laminate thickness. The material properties like Vickers hardness and fracture toughness were measured and evaluated along with the microstructure of the composites with prolonged high temperature exposure.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.3
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• pp.348-356
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• 2022

Supernumerary teeth develop from excessive proliferation and development of the dental lamina. Supernumerary teeth can cause several problems, including ectopic eruption, delayed eruption, root resorption of adjacent teeth, and diastema. Supernumerary teeth in infancy are rare and have rarely been reported. Case of a 2-day-old infant with 3 supernumerary teeth is presented here and the patient was followed up for 21 months. The erupted supernumerary tooth in the primary dentition was extracted under moderate sedation at the age of 14 months. Microcomputed tomography analysis of the extracted tooth confirmed microscopic root malformation. After extraction, the midline diastema was reduced and oral hygiene improved. Early diagnosis and prompt treatment can prevent complications of supernumerary teeth.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.21 no.2
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• pp.101-104
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• 2010

The origin and growth of laryngology is inseparably linked to the development of endoscopic surgery of the larynx. Phonomicrosurgery is a means of maximally preserving the layered microstructure of the vocal fold, that is, the epithelium and lamina propria. Phonomicrosurgery has developed from convergence of micro laryngoscopic surgical technique theory and the mucosal wave theory of laryngeal sound production. Improvements in technology (i.e., laryngoscopes, handled instruments, and lasers), which in part arise from developments in more frequently performed minimally invasive surgical procedures, will probably facilitate the next generation of procedural innovations. The best methods of optimizing phonosurgical outcomes include making an accurate diagnosis, completing a comprehensive voice evaluation, providing sufficient preoperative therapy, carefully selecting patients to undergo phonomicrosurgical procedures, and requiring sufficient postoperative rest and therapy. Phonomicrosurgery will continue to evolve as a result of the interdependent collaboration of surgeons with voice scientists, speech pathologist, and other voice professionals.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.2
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• pp.117-128
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• 2006

Free flap transplantation with microvascular anastomosis has been successfully performed by development of surgical technique, materials and postoperative monitoring equipments of flap. But success rate of microvascular anastomosis is influenced by various factors, and failure rate is about 5-10%. The most influential factor for success rate is surgical technique and other factors that influence failure of microvascular anastomosis are ischemic time of free flap, thrombus formation of anastomosis region and vascular spasm. Many studies has been published in microvascular anastomosis with histologic effect for irrigating solution. But local irrigation solution has been used clinically in microvascular anastomosis, the comparison with each solution, microhistological study for endothelial cell repair and vascular patency has not been reported. The heparin which is anti-thrombotic agent, and urokinase which is fibrinolytic agent are used for this study. Vascular patency and thrombus formation in experimental micro-arterial anastomosis, and endothelial repair were observed with histologic analysis, scanning electron microscopy, transmission electron microscopic examination. The results were obtained as follows: 1. In vascular patency test in 30 minute and 7 days after micro-arterial anastomosis, equal effects of good vascular patency were obtained in group of local irrigation with heparin and urokinase. 2. In thrombus formation in 7 days after micro-arterial anastomosis, equal effects of minimal thrombus formation were obtained in group of local irrigation with heparin and urokinase. 3. In toluidin blue staining in 7 days after micro-arterial anastomosis, local destruction of endothelial cell and inner elastic lamina were seen and endothelial repair was not seen. 4. In scanning electron microscope examination in 7 days after micro-arterial anastomosis, endothelial cell was not seen in peripheral to suture materials, thrombus associated fibrin network was observed. 5. In transmission electron microscope examination in 7 days after micro-arterial anastomosis, inflammatory cell was seen within smooth muscle cells in site of endothelial cell destruction, smooth muscle cell around suture material were arranged irregularly, some collagenous change were seen. From the results obtained in this study, same results of good vascular patency and anti-thrombotic effect of heparin and urokinase were obtained as a local irrigation solution, and repair of endothelial cell was not seen in 7 days after micro-arterial anastomosis.

• The Korean Journal of Quaternary Research
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• v.9 no.1
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• pp.43-60
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• 1995

The Kanweoldo Deposit in the Cheonsoo Bay western coast of Korean Peninsula is considered to be influenced by severe freezing condition under cold humid environment of the last glacial age. The evidence of severe freezing in the some upper part of the fine-grained Kanweoldo Deposit is characteristically irregular wavy la-mellar structure with the interval of 2∼8mm. In particular lamina show very compacted fabrics composed of rounded or spheroidal discrete aggregates covered by silt caps. Such laminar structure and associated micro-fabrics might owe to soil freezing such as ice segregation in lens form cryophoresis pressure from growing ice and disturbance by frost-creep. Furthermore pedogenesis of cold-humid type such as gleyzation or peseudo-gleyzation also might af-fect the kanweoldo Deposit in the priod of severe cold-humid cli-mate of the Wrm. The Kanweoldo sediment and organic remnant(16,708 B.P. with error limit of 250 years) affected by severe cryogenic activities sug-gest that the paleoclimate of Late Wrm in Korea might be so cold and humid as to engender the cryogenic structure in subaerial silty and sandy silt deposits.

• Annals of Rehabilitation Medicine
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• v.42 no.6
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• pp.884-887
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• 2018

We report a female proband carrying a de novo 5q34-q35.2 deletion breakpoint, and review the unique skeletal phenotype and possible genotype related to this mutation. The patient presented with a persistent head tilt and limited head rotation. Non-contrast-enhanced three-dimensional computed tomography of the cervical spine revealed several malformations including a bone cleft in the right pars interarticularis, a bone defect in both C5 lamina and the transverse foramen at C2-C3, agenesis of the right articular process of C5, bony fusion of C4-C5, and subluxation of the craniocervical joints. Several deformities of the cervical spine seen in this patient have not been associated with the 5q deletion. A review of 5q-related mutations suggests that abnormalities associated with MSX2 gene might cause cervical spine abnormalities.