• Electrical & Electronic Materials
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• v.10 no.6
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• pp.519-527
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• 1997

The micro crack was occurred where the stress concentrated by the thermal stress which was induced during the cooling period after molding process or by the various reliability tests. In order to estimate the possibility of development from inside micro crack to outside fracture, the fracture toughness of EMC should be measured under the various applicable condition. But study was conducted very rarely for the above area. In order to provide a was to decide the fracture resistance of EMC (Epoxy Molding Compound) of plastic package which is produced by using transfer molding method, measuring fracture is studied. The specimens were made with various EMC material. The diverse combination of test conditions, such as different temperature, temperature /humidity conditions, different filler shapes, and post cure treatment, were tried to examine the effects of environmental condition on the fracture toughness. This study proposed a way which could improve the reliability of LOC(Lead On Chip) type package by comparing the measured $J_{IC}$ of EMC and the calculated J-integral value from FEM(Finite Element Method). The measured $K_{IC}$ value of EMC above glass transition temperature dropped sharply as the temperature increased. The $K_{IC}$ was observed to be higher before the post cure treatment than after the post cure treatment. The change of $J_{IC}$ was significant by time change. J-integral was calculated to have maximum value the angle of the direction of fracture at the lead tip was 0 degree in SOJ package and -30 degree in TSOP package. The results FEM simulation were well agreed with the results of measurement within 5% tolerance. The package crack was proved to be affected more by the structure than by the composing material of package. The structure and the composing material are the variables to reduce the package crack.ack.

• Design & Manufacturing
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• v.17 no.2
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• pp.55-61
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• 2023

With femtosecond (fs) laser pulse irradiation on metals, various types of nano- and micro-scale structures can be naturally induced at the surface through laser-matter interaction. Two notable structures are laser-induced periodic surface structures (LIPSSs) and cone/spike structures, which are known to significantly modify the optical and physical properties of metal surfaces. In this work, we irradiate fs laser pulses onto various types of metals, cold-rolled steel, pickled & oiled steel, Fe-18Cr-8Ni alloy, Zn-Mg-Al alloy coated steel, and pure Cu which can be useful for precise molding and imprinting processes, and adjust the morphological profiles of LIPSSs and cone/spike structures for clear structural coloration and a larger range of surface wettability control, respectively, by changing the fluence of laser and the speed of raster scan. The periods of LIPSSs on metals used in our experiments are nearly independent of laser fluence. Accordingly, the structural coloration of the surface with LIPSSs can be optimized with the morphological profile of LIPSSs, controlled only by the speed of the raster scan once the laser fluence is determined for each metal sample. However, different from LIPSSs, we demonstrate that the morphological profiles of the cone/spike structures, including their size, shape, and density, can be manipulated with both the laser fluence and the raster scan speed to increase a change in the contact angle. By injection molding and imprinting processes, it is expected that fs laser-induced surface structures on metals can be replicated to the plastic surfaces and potentially beneficial to control the optical and wetting properties of the surface of injection molded and imprinted products.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.11.1-11.8
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• 2016

Background: Silk cocoon is composed of multiple layers. The natural silk cocoon containing all layers was cut as a rectangular shape as defined as total group. The inner and outermost layers were removed from the total group and the remained mat was defined as the middle group. The objectives of this study was to compare the total group with the middle group as a barrier membrane for the guided bone regeneration. Methods: The effects of these materials on the cellular proliferation and alkaline phosphatase (ALP) expression of MG63 cells were explored. For comparing bone regeneration ability, bilateral bone defects were created in calvarial areas in ten adult New Zealand white rabbits. The defects were covered with silk membranes of the middle group, with silk membrane of the total group used as the control on the contralateral side. The defects were allowed to heal for 4 and 8 weeks. Micro-computerized tomography (${\mu}CT$) and histological examination were performed. Results: The middle group exhibited a higher MTT value 48 and 72 h after treatment compared to the total group. ALP expression was also higher in the middle group. The results of ${\mu}CT$ and histologic examination showed that new bone formation was significantly higher in the middle group compared to the total group 8 weeks postoperatively (P < 0.05). Conclusions: In conclusion, the middle layer of the silk cocoon supports guided bone regeneration better than unprocessed silk cocoon.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.254-261
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• 2000

Since callus distraction technique was applied clinically for the correction of dentofacial deformity to the patients with hemifacial dysplasia by McCarthy in 1992, many surgeons have tried to apply this method to the maxillofacial region. But this technique has some drawbacks. One of the disadvantages of this technique is extensive scar formation in the facial area, which is a sequelae of extraoral approach for supraperiosteal dissection of the periosteum overlying the mandible. Recently, we have made an effort to perform this technique through intraoral approaches to prevent scar formation on the submandibular area and modified the design of the osteotomy, that is step osteotomy technique, to increase the raw bone surface on both osteotomized segments. The rationale for the application of this step osteotomy technique is to increase the amount of regenerated bone and the length of distraction, to avoid damage of inferior alveolar neurovascular bundle, and to increase initial stability of the splitted segments. Step osteotomy procedure can be done with fine micro-osteotomy saw through subperiosteal tunneling. Extraoral pins should be inserted before making the osteotomy. Since 1994 we have applied this technique at 8 sites In 5 patients with mandibular deficiencies: 2 cases of hemifacial microsomia, 1 case of developmental facial asymmetry and 2 cases of mandibular bony defect. Mandibular elongation have been achieved from 12 to 20mm in length. 1 out of 8 site, we experienced non-union in the case of mandibular body defect. Some skeletal relapse and growth retardation phenomenon have been observed in some cases with the longest follow-up of 48 months.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.5
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• pp.293-298
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• 2012

Purpose: The aim of this study was to evaluate the bone regeneration ability of 1% tetracycline (TC)-loaded silk fibroin membrane (SFM), in a rabbit calvarial defect model. Methods: Twenty New Zealand white rabbits were used for this study. Bilateral round defects were made on the rabbit parietal bone, using trephine bur with an 8 mm diameter. TC-loaded SFM or SFM was covered on the right parietal bone defect, and the left parietal bone defects were uncovered for the control. The animals were humanely sacrificed at 4 or 8 weeks postoperatively. A micro-computerized tomography (${\mu}$-CT) of each specimen was taken for analysis of bone regeneration. Hematoxylin and Eosin stain were done to observe histological findings. Results: From the ${\mu}$-CT results, regenerated bone volume ($mm^3$) of 1% TC-loaded SFM, SFM, and control were $7.80{\pm}5.87$, $8.79{\pm}3.44$, and $10.61{\pm}5.3$ at 4 weeks postoperatively, respectively (P>0.05). Regenerated bone volume ($mm^3$) of 1% TC-loaded SFM, SFM, and control were $36.56{\pm}8.50$, $25.86{\pm}8.17$, and $19.09{\pm}5.07$ at 8 weeks postoperatively, respectively (P<0.05). Conclusion: The 1% TC-loaded SFM showed more bone regeneration than the SFM and the uncovered control, in guided bone regeneration.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.242-245
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• 2010

Pierre Robin sequence (PRS) describes the clinical triad of micro- and/or retrognathia, glossoptosis and cleft soft palate. Glossopexy has been demonstrated to be an effective treatment in selected cases of obstruction caused by glossoptosis (generally 6 to 10 months of glossopexy period). If radiofrequency therapy (RF) can reduce tongue volume in PRS, it will be helpful in early releasing of the glossopexy. Two-dayold patient showed a PRS triad. Intermittent cyanosis, respiratory difficulty and feeding problems were also observed. The respiration was not improved and prolonged intubation increased the possibility of respiratory complications like pneumonia. The surgical intervention- glossopexy and RF was done 20 days after birth. We applied RF combined with conventional glossopexy and could get successful results while reducing the overall treatment time to 6 weeks. The follow-up until 12 months after birth was uneventful. Considering that early recovery is highly beneficial to PRS patients by reducing risks associated with glossopexy and low energy RF application is very simple and low risk to patient, our combination therapy should be considered for the treatment of airway problem related to PRS.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.1
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• pp.1-12
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• 2013

Purpose: Vascular endothelial growth factor (VEGF)-C and its tyrosine kinase receptor, VEGF receptor (VEGFR)-3 are recently known to have lymphangiogenic activities in various tumor types. In this study, we determined whether the expression of lymphangiogenic factors correlate with nodal metastasis or survival in a nude mouse model of oral squamous cell carcinoma (OSCC). Methods: Three OSCC cells (KB, SCC4, SCC9) were xenografted into the right mandibular gland of athymic nude mice. The mice were followed for tumor development and growth, and the mice were sacrificed when they had lost more than 20% of their initial body weight, or the diameter of the induced tumor exceeds 20 mm. After necropsy, the murine tumors were examined histologically and radiologically (micro-positron emission tomography computed tomography) for regional or distant metastasis. We performed immunohistochemical assays with anti-VEGF-C, VEGFR-3, CD105, and D2-40 antibodies. Immunofluorescence double staining for LYVE-1/CD31 was also performed. To quantify the VEGF-C and VEGFR-3 level in the cancer tissue, Western blotting was performed. Finally, we determined the correlation between the degree of expression of VEGF-C/VEGFR-3 and the mean survival time. Results: OSCC tumor cells into the mandibular gland of the nude mice successfully resulted in the formation of recapitulating orthotopic tumor. Tumor cells of the induced tumor did not express VEGF-C. VEGF-C/VEGFR-3 expression was mainly distributed in the endothelial cells of the stromal area. There were no correlation between the degree of expression of VEGF-C/VEGFR-3 and the mean survival time of mice injected with different OSCC cell lines. Conclusion: An recapitulating orthotopic model of OSCC in nude mice was established, which copies the cervical nodal metastasis of human OSCC. Overexpression of lymphangiogenic factors seems to have no effect on survival of hosts in this in vivo experiment.

• Archives of Reconstructive Microsurgery
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• v.22 no.1
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• pp.18-23
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• 2013

Purpose: For reconstruction of lower extremity defects, various flaps can be used and the appropriate flap must be selected and applied according to the size of the defect. In particular, in cases where the defect size is small to moderate, thinner or smaller volume flaps are useful. The authors performed reconstruction of small to moderate defects on the lower extremities using superficial circumflex iliac artery perforator free flaps and are reporting the results. Materials and Methods: Fifteen patients underwent reconstruction of defects on lower extremity areas using superficial circumflex iliac artery perforator free flaps from July 2011 to July 2012 at this hospital. The flaps were elevated from above the deep fat layer, and, in all cases, the vessel diameter of the flaps was less than 1mm, with the exception of superficial vein that accompanied it. Results: The mean follow up period was 4.46 months, and, despite a partial loss in the flap in two cases, there were no total losses. All donor sites were closed with primary closure, and there was no occurrence of complications, such as hematomas, seromas, or lymphorrheas. The patients were highly satisfied with the donor site scar since it could be masked by underwear. Conclusion: Compared to other flaps, superficial circumflex iliac artery perforator free flaps are thinner in thickness and smaller in volume, which results in a more natural contour of the recipient site after the operation. In addition, since the flap can be elevated from supra-deep fat layer, the operation time can be shortened, and lymphorrhea can be prevented, which in turn lessens donor-site morbidity.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.6
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• pp.377-383
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• 2012

Purpose: The aim of this study was to evaluate the effect of 4-hexylresorcinol and hydroxyapatite combination graft on bone regeneration in the rabbit calvarial defect model. Methods: Ten New Zealand white rabbits were used for this study. Bilateral round shaped defects (diameter: 8.0 mm) were created on the parietal bone. 4-hexylresorcinol and hydroxyapatite combination graft material was grafted into the right parietal bone defect area (experimental). The left bone defect area was not filled with anything (control). The animals were sacrificed at 4 weeks and 8 weeks after grafting. A micro-computerized tomography of each specimen was taken, and the specimens were stained for histological analysis. Results: The average value of bone mineral density (BMD) and Bone volume (BV) was higher in the experimental group than in the control group at 4 weeks and 8 weeks after surgery. However, the difference was not statistically significant (P>0.05) at 8 weeks after grafting. The BMD and BV in the experimental group at 4 weeks after surgery was significantly higher than those in the control group (P<0.05). Conclusion: 4-hexylresorcinol and hydroxyapatite combination graft material showed higher initial bone formation than the control, however, there was no difference at 8weeks after operation.

• Journal of Information Display
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• v.2 no.2
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• pp.52-60
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• 2001

The electrical and mechanical properties in indium-tin-oxide films deposited on polymer substrate were examined. The materials of substrates were polyethersulfone (PES) which have gas barrier layer and anti-glare coating for plastic-based devices. The experiments were performed by rf-magnetron sputtering using a special instrument and buffer layers. Therefore, we obtained a very flat polymer substrate deposited ITO film and investigated the effects of buffer layers, and the instrument. Moreover, the influences of an oxygen partial pressure and post-deposition annealing in ITO films deposited on polymer substrates were clarified. X-ray diffraction observation, measurement of electrical property, and optical microscope observation were performed for the investigation of micro-structure and electro-mechanical properties, and they indicated that as-deposited ITO thin films are amorphous and become quasi-crystalline after adjusting oxygen partial pressure and thermal annealing above $180^{\circ}C$. As a result, we obtained 20-25 ${\Omega}/sq$ of ITO films with good transmittance (above 80 %) of oxygen contents with under 0.2 % and vacuum annealing. Furthermore, using organic buffer layer, we obtained ITO films which have a rather high electrical resistance (40-45 ${\Omega}/sq$) but have improved optical (more than 85 %) and mechanical characteristics compared to the counterparts. Consequently, a prototype reflective color plastic film LCD was fabricated using the PES polymer substrates to confirm whether the ITO films could be realized in accordance with our experimental results.