• Archives of Plastic Surgery
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• 제33권5호
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• pp.552-556
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• 2006

Purpose: As the use of computed tomographic scanning spread, the diagnosis of blow-out fractures of the medial orbital wall increased. Conventionally, the surgery of blow-out fractures in medial orbital wall was performed by various approaches with external incision or endoscopic approach. Although the field of orbital surgery has progressed significantly during the last decade, accurate realignment and replacement of component is difficult due to lack of visualization of the fracture site, blind dissection of the orbital wall, and difficulty in insertion of implant. In order to overcome these shortcomings, we explored the use of endoscopic transnasal approach together with subciliary approach. Methods: The entrapped periorbital tissues in the ethmoid sinus were completely reduced endoscopically, and the bone defect of medial orbital wall was reconstructed with $Medpor^{(R)}$ insertion via subciliary approach. This technique was applied to 13 patients who had medial orbital wall fracture. Results: The patients were followed-up for 3 to 24 months with an average of 9 months. The postoperative courses were satisfactory in all cases. Conclusion: The conjunction of endoscopic transnasal and subciliary approach technique seems to produce good results in medial orbital wall fracture.

• Journal of Welding and Joining
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• 제21권2호
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• pp.50-56
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• 2003

Metal matrix composites(MMC) consist of metal matrix into which is distributed a second solid phase. The normal intension is to develop a material with superior mechanical properties (for example increased toughness, stiffness and wear resistance) compared to those inherent in the matrix component. In this study, WC-12%Co/low carbon steel MMC overlays have been prepared by Gas Metal Arc Welding(GMAW) according to feeding rate of WC-12%Co grit. The macro and microstructures were examined using optical microscopy (OM) and scanning electron microscopy(SEM) each other. The characteristics of hardness and wear resistance have been investigated. WC-12%Co/low carbon steel MMC overlays which have been taken good beads without porosity and cracks were manufactured by method of GMAW. Matrix of overlayed surface was seen as fish bone and faceted dendrite structures. It was known that structures were iron tungsten carbides, Fe$_{6}$W$_{6}$C which have been occurred by melting of WC-12%Co grits. After MMC had been tested by block-roll wear test it was known that WC-12%Co/low carbon steel MMC has a excellent wear resistance by exiting Fe6w6c and WC-12%Co grit. The consequence was that region of overlay with Fe$_{6}$W$_{6}$C phase has been showed a model of adhesive wear, but region of overlay with WC-12%Co grit was restrained as a result of mechanism that wear of WC-12%Co grit is not adhesive but fracture.racture.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권1호
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• pp.16-23
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• 2002

To understand the micro-mechanical changes and the effects of the fluoride on rat's femur after administration of sodium fluoride, the three-point bending test, acoustic emission analysis during the three-point bending test and scanning electron microscopy were performed. The obtained results were as follows: 1. Bone strength increased in the rats given 1, 5, 10 and 20 ppm of fluoride but, there were no statistical significances (p>0.05). 2. With increasing the concentration of fluoride, most AE events released rapidly just before the maximum load and smaller events were recorded than the control group's. The average of cumulative AE event counts until maximum load of the femur in 20 ppm group were significantly small with respect to the control group's (p<0.05). 3. Fracture surfaces were well coincide with the results of acoustic emission behavior. Analyses of fracture surfaces indicated that, consistent with its the highest load, rat femur in 20 ppm fluoride group displays the roughest surface.

• Corrosion Science and Technology
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• 제17권3호
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• pp.91-100
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• 2018

Development of biodegradable implants for treatment of complex bone fractures has recently become one of the priority areas in biomedical materials research. Multifunctional corrosion resistant and bioactive coatings containing hydroxyapatite $Ca_{10}(PO_4)_6(OH)_2$ and magnesium oxide MgO were obtained on Mg-Mn-Ce magnesium alloy by plasma electrolytic oxidation. The phase and elemental composition, morphology, and anticorrosion properties of the coatings were investigated by scanning electron microscopy, energy dispersive spectroscopy, potentiodynamic polarization, and electrochemical impedance spectroscopy. The PEO-layers were post-treated using superdispersed polytetrafluoroethylene powder. The duplex treatment considerably reduced the corrosion rate (>4 orders of magnitude) of the magnesium alloy. The use of composite coatings in inducing bioactivity and controlling the corrosion degradation of resorbable Mg implants are considered promising. We also applied the plasma electrolytic oxidation method for the formation of the composite bioinert coatings on the titanium nickelide surface in order to improve its electrochemical properties and to change the morphological structure. It was shown that formed coatings significantly reduced the quantity of nickel ions released into the organism.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제27권1호
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• pp.25-31
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• 2001

The titanium miniplate osteosynthesis system has been used for fixation of bone fragments in the maxillofacial areas due to easy manipulation and even has been proposed for unnecessity of miniplate removal because of the biocompatibility and the corrosion resistance. But recently, there have been some suggestions for its removal, on the basis of findings that there have been pigmentations around the adjacent tissues during miniplate removal procedure and they are the depositions of metal particles. Purposes of this study are to ascertain the presence and nature of pigmentation observed within tissues adjacent to titanium miniplate, and to suggest possible causes of it. We could observe the black pigmentation during miniplate removal procedure for recent about 1.5 year. Pigmented tissues were stained with hematoxylin-eosin(H-E) for light microscophic(LM) examination to investigate the black pigmentations and the histomorphology around them. The scanning electron microscopy(SEM) with energy dispersive X-ray(EDX) analysis was used to examine the ultrastructural nature of pigmentations. Many metal particles with variable sizes and shapes were seen in the connective tissue by SEM and were identified as titanium by EDX.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.105-115
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• 2006

Thickness is a commonly used parameter in product design and manufacture. Its intuitive definition as the smallest dimension of a cross-section or the minimum distance between two opposite surfaces is ambiguous for intricate solids, and there is very little reported work in automatic computation of thickness. We present three generic definitions of thickness: interior thickness of points inside an object, exterior thickness for points on the object surface, and radiographic thickness along a view direction. Methods for computing and displaying the respective thickness values are also presented. The internal thickness distribution is obtained by peeling or successive skin removal, eventually revealing the object skeleton (similar to medial axis transformation). Another method involves radiographic scanning along a viewing direction, with minimum, maximum and total thickness options, displayed on the surface of the object. The algorithms have been implemented using an efficient voxel based representation that can handle up to one billion voxels (1000 per axis), coupled with a near-real time display scheme that uses a look-up table based on voxel neighborhood configurations. Three different types of intricate objects: industrial (press cylinder casting), sculpture (Ganesha idol), and medical (pelvic bone) were used for successfully testing the algorithms. The results are found to be useful for early evaluation of manufacturability and other lifecycle considerations.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.40.2-40.2
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• 2010

In this study, oxidized alginate/gelatin/biphase calcium phosphate (BCP)- based hydrogel composites were fabricated. Alginate sodium was oxidized by periodate. The oxidized product was confirmed by using $^1H$ and $^{13}C$ NMR spectra. The number average molecular weight ($M_n$), the average molecular weight ($M_w$) of the oxidized alginate were determined by Gel Permeation Chromatography (GPC). The hydrogel was formed from the oxidized alginate and gelatin solution via Schift-base reaction. The hydrogel showed a highly porosity by a Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP). Crosslinked density of the gel matrix were assessd by trinitrobenzene sulfonic acid (TNBS) assay that shows a high effect on swelling ratio. Increment of the crosslinked desity resulted in enhancing compressive strength of the hydrogel composite. The cytotoxity of hydrogel was assessed with osteoblast MG-63. The hydrogel composites show a high compatibility. The obtained results showed a potential application for bone regeneration in future.

• 대한의용생체공학회:의공학회지
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• 제9권1호
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• pp.47-60
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• 1988

N-n-Propylacrylamide는 n-propyl bromide와 acrylamide로 부터 합성하였고, 합성된 N-n-propylacrylamide를 THF용매속에서 개시제로 AIBN을 사용하여 $60^{\circ}C$에서 acrylamide와 공중합시켰다. 그리고 합성된 단량체와 공중합체는 NMR과 IR에 의하여 확인하였다.

• The Korean Journal of Pain
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• 제2권1호
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• pp.61-65
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• 1989

Chloroma is a localized myeloblastic tumor which may develop during the course of myelogenous leukemia or as a presenting sign of the disease. A 47-year-old female diagnosed as chronic myelogenous leukemia in her hematologic remission period complained of left lower leg pain. The lumbar-spine series showed multiple osteolytic changes in the left lateral border of the lumbar spine. An inhomogenous soft tissue mass involving left lateral aspects of lumbar vertebrae was identified by CT-scanning. At the first pain attack, lumbar epidural steroid and local anesthetic injection could abolish her pain and the patient could go a few days without pain. The following radiation therapy could also improve the symptom and retain the pain free interval. One month later, a second pain attack occurred and lumbar and caudal epidural steroid and local anesthetic injections could result only in an incidental relief of pain. Radiation and chemotherapy were started but failed to relieve pain. A neurolytic block was considered but the patient's general condition was aggravated and even verbal communication with her became impossible.

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.3950-3956
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• 2012

In order to improve the bioactivity and mechanical properties of hydroxyapatite (HAp), chitosan (Chi) was in situ combined into HAp to fabricate a composite scaffold by a sublimation-assisted compression method. A highly porous film with sufficient mechanical strength was prepared and the bioactivity was investigated by examining the apatite formed on the scaffolds incubated in simulated body fluid. In addition, the cytotoxicity of the HAp/Chi composite was studied by evaluating the viability of murine fibroblasts (L-929 cells) exposed to diluted extracts of the composite films. The apatite layer was assessed using scanning electronic microscopy, inductively coupled plasma-optical emission spectrometry and weight measurement. Composite analysis showed that a layer of micro-sized, needle-like crystals was formed on the surface of the composite film. Additionally, the WST-8 assay after L-929 cells were exposed to diluted extracts of the composite indicated that the HAp/Chi scaffold has good in vitro cytocompatibility. The results indicated that HAp/Chi composites with porous structure are promising scaffolding materials for bone-patch engineering because their porous morphology can provide an environment conductive to attachment and growth of osteoblasts and osteogenic cells.