• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.8-15
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• 2003

This study was carried out to investigate the dimensional stability of wood treated with PEG for better utilization of domestic small-diameter logs. Four species of ring- porous wood(Quercus mongolica F_ISCH, Quercus variabilis B_LUME, Fraxinus rhynchophylla H_ANCE, Paulownia coreana U_YEKI,) and four species of diffuse-porous wood(Prunus sargentii R_EHDER, Betula davurica P_ALL, Populus tomentiglandulosa T. L_EE, Cornus controversa H_EMSLEY) were used for this experiment. The shrinkage of wood decreased with increasing the concentration of PEG. The shrinkage of diffuse- porous woods was lower than that of ring-porous woods. The weight gain increased in proportional to the PEG concentration. Diffuse-porous woods showed a little higher weight gain than ring-porous woods. Bulking effect also increased with increasing the PEG concentration, but was in inverse proportional to the molecular weight of PEG. Diffuse-porous woods showed higher bulking effect than ring-porous woods. Consequently, diffuse-porous woods showed better dimensional stability than ring- porous woods. It was considered that dimensional stability was affected by characteristics of wood such as vessel and tylosis, and density.

• Archives of Craniofacial Surgery
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• v.10 no.1
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• pp.23-28
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• 2009

Purpose: Blow out fracture can present tenderness, swelling, enophthalmos, extraoccular muscle limitation, paresthesia, diplopia according to severity of injury, so reconstruction of blow out fracture is important. Orbital soft tissue should be in orbit and defected orbital wall should be corrected by autologus tissue or alloplastic implants. Every implants have their merits and faults, every implants are used various. This study was designed to compare the sequelae of blow-out fracture repair using the alloplastic implants: micro-titanium mesh(Micro Dynamic titanium $mesh^{(R)}$, Leibinger, Germany), porous polyethylene ($Medpor^{(R)}$, Porex, USA), absorbable mesh plate(Biosorb $FX^{(R)}$ . Bionx Implants Ltd, Finland). Methods: Between January 2006 and April 2008, 52 patients were included in a retrospective study analysing the outcome of corrected inferior orbital wall fracture with various kind of implants. Implants were inserted through subciliary incision. Twenty patients were operated with micro-titanium mesh, fourteen patients with porous polyethylene and eighteen patients with absorbable mesh plate. In comparative category, enophthalmos, diplopia, range of motion of extraoccular muscle, inferior orbital nerve injury were more on frequently statistically in patients. Results: Fourteen of 18 patients underwent surgical repair to improve diplopia, 11 of 17 patients to improve parasthesia, 11 of 15 patients to improve enophthalmos, 8 of 9 patients to improve extraoccular muscle limitation. Duration of follow-up time ranged from 6 months to 12 months(mean, 7.4 months). There was no statistic difference of sequelae between micro titanium mesh and porous polyethylene and absorbable mesh plate in blowout fracture, inferior wall. Conclusion: There is no difference of sequelae between micro-titanium mesh, porous polyethylene and absorbable mesh plate in blow-out fracture, inferior wall. The other factors such as defect size, location, surgeon's technique, may influence the outcome of blow-out fracture repair.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.2
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• pp.1965-1970
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• 1970

The experiment was carried out in order to improve the leakage stopping work in the irrigation canal founding on the porous soil. But the experiment had many problems to be studied more owing to the insufficient time and facilities. The results obtained are summarized as follows; 1. Polyethylene film is estimated not to make strength decrease owing to buring in the subsoil, but to make owing to the sunlight. 2. Coated nylon shows the tendency to deteriorate strength when it is buried in the earth or exposed to the sun for long time, but leakage is all but impermeability generally. 3. Leakage loss rates for one hour show some differences in the canal to be full with water in accordance with operating methods, that is, the clay lining section is 12.6%, the coated nylon lining section is 1.7%, the polyethylene film lining section is 1.3%, respectively. 4. Leakage quantities per wetted perimeter unit area show $3.556cc/cm^2/hr$. in the clay lining section, $1.574cc/cm^2/hr$. in the coated nylon section, $0.695cc/cm^2/hr$. in the polyethylene film lining section, respectively. 5. When the construction fund make the clay lining section as a standard, the polyethylene film section is 92.1%, the coated nylon section is 174.2%, respectively. But, the unit cost of execution may be low when the polyethylene film and the coated nylon will enable to mass-produce for the purpose of execution.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.837-841
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• 2003

Duplex microstructure of zirconia and alumina has been achieved via an organic-inorganic solution technique. Zirconium 2,4-pentanedionate, aluminum nitrate and polyethylene glycol were dissolved in ethyl alcohol without any precipitation. The organicinorganic precursor gels were turned to porous powders having volume expansion through explosive, exothermic reaction during drying process. The volume expansion was caused by abrupt decomposition of the organic groups in the gels during the vigorous exothermic reaction. The volume expanded, porous powders were crystallized and densified at 1500$^{\circ}C$ for 1 h. At the optimum amount of the PEG polymer, the metal cations were well dispersed in the solution and a homogeneous polymeric network was formed. The polymer content also affected on the specific surface area of the synthesized powder and the grain size of the sintered composite.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.152.1-152
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• 2003

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.3
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• pp.283-291
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• 2008

The malar mound defines the contour of the lateral face between the inferior orbital rim and the mandible, and hypoplasia or asymmetry of this region is readily noticeable. A flat, hypoplastic malar eminence can make the face blunt and wearisome, which contributes to a premature aged appearance. Patients with congenital or traumatic flattening of the malar eminence can obtain esthetic improvement with implants. Indications for placement of malar implants to improve the appearance of subtle flattening or to enhance the esthetic harmony of a patient's face have been suggested in several studies. Many augmentation materials, such as silicone, proplast, polyamide, and porous polyethylene implants have been used. Many methods of localization have been described, the key to proper placement of the implants lies in a through understanding of the esthetics of the malar mound. From August 2001 to June 2007, 12 patients with malar depression who visited the Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital were treated by augmentation malarplasty with Porous polyethylene. The location and amount of augmentation are determined by preoperative interview, physical examinations, facial models and radiographic findings. 12 patients were satisfied with the results of augmentation malarplasty and severe complications were not occurred.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.380-384
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• 2010

Purpose: Distinguishing different types of implants and assessing the position and size of implants by radiologic exam after orbital wall reconstruction is important in determining the surgery outcome and forecasting prognosis. We observed time-dependent density changes in three types of implants (porous polyethylene, resorbing plate and titanium mesh plate) by performing facial bone CT after orbital wall reconstructions. Methods: A total of 32 patients, who had underwent orbital wall fracture surgery from October 2006 to March 2009 and received facial bone CT as outpatients at 1 postoperative year were included in the study. Follow-up facial bone CT was performed on the patients pre- operatively, 1 month post-operatively, and 1 year post-operatively to observe the status of the orbital implants. Medpor $^{(R)}$ (Porex Surgical, Inc., Newnan, Ga.) was used as porous polyethylene and followed-up in 14 cases; for resorbing plate, Synthes mesh plate (Synthes, Oberdorf, Switzerland) was used in the reconstruction, and followed-up in 11 cases; and titanium mesh plate usage was followed-up in 7 cases. Computed tomographic scan (CT) and water's view were done for radiography, and hounsfield unit (HU) was used to compare density of those facial bone CT. Wilcoxon signed rank test was applied to statistically verify measurement difference in each group of hounsfield units. Results: Facial bone CT examination performed in 1 month post-operative showed that the density of porous polyethylene, resorbing plate and titanium mesh plate were -42.07, 105.67 and 539.48 on average, respectively. Among the three types of implants, titanium mesh plate showed the highest density due to its radiopaque feature. Following up the density of three types of implants in CT during 1 year after the orbital wall fracture surgery, the density of porous polyethylene increased in 10.52 House Field Units and the resorbing plate was decreased in 26.87 HouseField Units. There were no significant differences between densities in 1 month post-operatively and 1 year post-operatively in each group ($p{\geq}0.05$). Conclusion: We performed facial bone CT on patients with orbital fractures during follow-up period, distinguishing the types of implants by the different concentration of implant density, and the densities showed little change even at 1 year post-operative. To observe how implant densities change in facial bone CT, further studies with longer follow-up periods should be carried out.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.2
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• pp.127-132
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• 1998

$Medpor^{(R)}$(porous polyethylene) Surgical Implants are used for the augmentation or restoration of bony contour in craniofacial defects. The purpose of this study is to evaluate the ingrowth of soft tissue and bone after application in calvaria of rats. The experiment was carried out in 60 rats. The reflected periosteum was resutured after implantation of $Medpor^{(R)}$ as a experimental site, while in the calvarial bone the reflected periosteum resutured without implantation as a control site. The histologic examination was performed after 1-, 2-, 4-, 8-, 12-, 24-weeks implantation in calvaria of rats. I concluded that there was abundant ingrowth of soft tissue and bone without any adverse tissue response and that it shows good stability.

• Journal of Powder Materials
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• v.10 no.5
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• pp.310-317
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• 2003

Two-component ceramic (alumina-zirconia) composites were fabricated by a soft-solution process in which polyethylene glycol (PEG) was used as a polymeric carrier. Metal salts and PEG were dissolved in ethyl alcohol without any precipitation in 1:1 volume ratio of alumina and zirconia. In the non-aqueous system, the flammable solvent made explosive, exothermic reaction during drying process. The reaction resulted in formation of volume expanded, porous precursor powders by a vigorous decomposition of organic components in the precursor sol. The PEG content affected the grain size of sintered composites as well as the morphology of precursor powders. The difference of microstructure in sintered composite was attribute to the solubility and homogeneity of metal cations in precursor sol. At the optimum amount of the PEG polymer, the metal ions were dispersed effectively in solution and a homogeneous polymeric network was formed. It made less agglomerated particles in the precursor sol and affected on uniform grain size in sintered composite.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.481-484
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• 2009

Purpose: Cleidocranial dysostosis is a rare hereditary disorder affecting bones that develop by intramembranous formation. The typical features include excessive growth of transverse diameter of the skull, hypoplastic clavicles, low height and characteristic facial features. Methods: A 28 years old female patient visited by frontal area depression. The diagnosis was performed by computed tomographic study and radiographic imaging. The patient has widely opened anterior fontanelle, partial fused metopic suture, multiple wormian bone and supernumenary impacted teeth. Under the coronal incision, we exposed depressed frontal area and corrected with Medpor block carving. Results: Postoperatively, frontoparietal skull was aestheticlly improved and she was satisfied with the results. Conclusion: Authors report a case of cleiodocranial dysostosis who has been done correction of abnormal skull shape by Medpor$^{(R)}$ insertion.