• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.80.1-80
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• 1998

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.121-122
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• 2011

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.406-409
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• 2004

A blue phosphor(ZnS:Cu) is manufactured by solid state reaction for ACPEL(AC powder EL). The effect of artificial defect on phosphor surface on the ZnO phase conversion and resulting luminescence have been studied. It was found that ZnS:Cu could converse to cubic phase more easily due to the formation of artificial defect on 1st fired phosphor by ball-milling process, resulting in improvement of luminescence of phosphor phosphors under the driven EL condition. We found out an optimized ball-mill condition through considering effect of each ball-mill conditions such as milling time and milling rpm on defect. Also we determined relationship between emission luminescence and phase of phosphor based on analyses of crystal structures of phosphors. A significant improvement above 30% was observed in electroluminescence by the artificial defect on ZnS:Cu phosphors compared to non-treated phosphors.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.3
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• pp.217-227
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• 1998

Calcium sulfate(plaster of Paris) has been used in dental and orthopedic surgery for about 100 years. It is well known that the plaster is bioresorbable, biocompatible, defect conformable and moldable. The purpose of this study is to evaluate two effects of calcium sulfate on bone regeneration, that is, the effects of graft materials and barrier for bone regeneration. Cortical bone defects were formed for recipient site on the femurs of 19 Sprague-Dawley rats. The autogenous particulated bone and calcium sulfate were grafted to the defects. Calcium sulfate paste, $Gore-Tex^R$ membrane(W.L. GORE & ASSOCIATES LTD., U.S.A.) and rubber sheet were used for the shielding materials. The results were as follows : 1. Calcium sulfate that had been grafted in the cortical bone defect was almost resorbed before bone remodeling, resultantly had little effect on bone regeneration. 2. Resoption process of calcium sulfate grafted on the bone grafting area tends to be accelerated, as being divided into numerous small particles progressively. Under the situation where the calcium sulfate was protected, with the coverage of fascia, $Gore-Tex^R$ membrane or rubber sheet, new bone formation was confirmed with presence of calcium sulfate particles over 6 weeks after grafting. 3. In the case of calcium sulfate covered with membrane, distinct bone formation was observed on the marrow space of femur adjacent to the plaster mass. 4. Rubber shielded plaster group revealed new bone trabeculae under the rubber sheet, but it showed ischemic degeneration of superficial cortical bone.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.26.1-26.6
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• 2016

Background: Xenologous or synthetic graft materials are commonly used as an alternative for autografts for guided bone regeneration. The purpose of this study was to evaluate effectiveness of carbonate apatite on the critical-size bone defect of rat's calvarium. Methods: Thirty-six critical-size defects were created on 18 adult male Sprague-Dawley rat calvaria under general anesthesia. Calvarial bones were grinded with 8 mm in daimeter bilaterally and then filled with (1) no grafts (control, n = 10 defects), (2) bovine bone mineral (Bio-$Oss^{(R)}$, Geistlich Pharma Ag. Swiss, n = 11 defects), and (3) hydroxyapatite ($Bongros^{(R)}$, Bio@ Inc., Seongnam, Korea, n = 15 defects). At 4 and 8 weeks after surgery, the rats were sacrificed and all samples were processed for histological and histomorphometric analysis. Results: At 4 weeks after surgery, group 3 ($42.90{\pm}9.33%$) showed a significant difference (p < 0.05) compared to the control ($30.50{\pm}6.05%$) and group 2 ($28.53{\pm}8.62%$). At 8 weeks after surgery, group 1 ($50.21{\pm}6.23%$), group 2 ($54.12{\pm}10.54%$), and group 3 ($50.92{\pm}6.05%$) showed no significant difference in the new bone formation. Conclusions: $Bongros^{(R)}$-HA was thought to be the available material for regenerating the new bone formation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.3
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• pp.258-262
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• 2001

Distraction osteogenesis(DO) can be performed in the bony defect associated with trauma, anomaly, and various kinds of disease. The gap generated by DO is filled with growing callus : during the period of distraction, the osteogenesis is continued. However, there have been few reports about expression pattern of growth factors in newly formed bone during the consolidation periods. We performed DO in the mandibular defect case and studied the expressed pattern of growth factors. Its pattern was compared to that of the same patient. BMP-2 and -4 were strongly expressed in the DO site. Particularly, BMP-4 was not expressed in the normal mature bone, but expressed in new bone in DO. However, there was no difference in the FGF-7 expression between the sites. Therefore, strong expression of BMP-4 are related to new bone formation in DO and they may not be related to the normal homeostasis in human bone. Though FGF-7 is related to the growth of keratinocyte, it may have minimal role in the DO and normal mature bone.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.4
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• pp.259-264
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• 2000

In this study, we quantitatively measure the ion ranges of arsenic with energies ranging from 10 KeV to 100 KeV, implanted at $3^{\circ}$, $9^{\circ}$ $15^{\circ}$ the (100) plane, and the damage created during ion implantation. To obtain detailed information of ion range and damage distributions in low energy region where elastic collisions dominate the slowing down process, molecular dynamics computer simulation was performed and compared to the existing results. The effects of implant energy and degree on damage generation are present. The number of vacancy were calculated from the deposited energy using Kinchin-Pease equation. In the energy range 10 keV-100 keV, simulations show that the number of Frenckel pairs produced by As-ion bimbardment is 9 and incident angle dependence of the vacancy was the same but defects were distributed at different depth.

• Electrical & Electronic Materials
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• v.8 no.5
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• pp.640-647
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• 1995

In this study, the BaTiO$\sub$3/ capacitor add to MnO$\sub$2/ like depressor and shifter were investigated for temperature or voltage compensation by structural and electrical analysis. The relative density of BCTM, generating poly crystall and formation of lattice defect, has a 90[%] over as the CaTiO$\sub$3/ come out to control grain size. The current density of BCTM2 increased non-ohmic in high-electric field but that BCTM3 and BCTM4 had a few changing. The BCTM3 and BCTM4 unformated grain boundary shown temperature compensation properties, so that the dielectric constant was low value. The curie point was near 140[.deg. C] in BCTM1 and BCTM4, but BCTM3 and BCTM4 not shown the curie point. It is found that the charging energy of BCTM4 was changed 6[%] according to rising temperature from room temperature to 417[K]. The formation of BaMnO$\sub$3/ was low dielectric constant to change frequency and temperature.

• Archives of Craniofacial Surgery
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• v.25 no.3
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• pp.150-154
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• 2024

This case report describes a rare occurrence of pyogenic granuloma (PG) in the hard palate deviating from its typical gingival location that led to the formation of an alveolar cleft. The aggressive growth pattern of the lesion, with atypical progression from a pedunculated nodule to an alveolar cleft, raised concern. The diagnosis was based on magnetic resonance imaging and computed tomography findings, which revealed a tadpole-shaped lesion originating from the midline hard palate. The differential diagnosis included a minor salivary gland tumor. Surgical excision was performed under general anesthesia and resulted in a mucosal defect without nasolabial fistula formation or bone exposure. The palatal defect was packed with oxidized regenerated cellulose and closed with Vicryl Rapide sutures, both of which contributed to the patient's successful outcomes. Our comprehensive approach, extending across the stages of surgical planning, execution, and postoperative care, demonstrated the advantages of a multidisciplinary strategy for the accurate diagnosis and effective treatment of palatal PGs. This report makes a meaningful contribution to the existing literature on common oral lesions by emphasizing the importance of a broad differential diagnosis and a systematic approach to oral pathologies. It also raises clinical awareness of PGs with atypical presentations and the diagnostic challenge that they pose.

• Polymer(Korea)
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• v.34 no.2
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• pp.108-115
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• 2010

The effects of acid-treated MWCNT and coupling agent on properties of MWCNT/SBR are investigated in this work. The MWCNTs oxidized using sulfuric and nitric acids were analyzed by the Raman scattering and Fourier transformed infrared spectroscopy(FT-IR). The FT-IR results indicate the presence of -COOH groups in the treated samples, and Raman spectroscopy of the acidtreated MWCNTs further corroborates the formation of surface defect due to the introduction of carboxyl groups. And the nanocomposites reinforced with MWCNTs were characterized extensively using the scanning electron microscopy(SEM), electrical conductivity, thermal conductivity, and tensile properties measurements. The results showed that nanocomposites onto acid-treated MWCNTs enhanced mechanical properties compared to those containing MWCNTs without acid treatment. These findings confirmed the improved interfacial interactions between MWCNTs and SBR arising from the coupling agents. But the electrical and thermal conductivity of nanocomposites decreased due to the chopping and formation of surface defects of MWCNTs.