• Korean Journal of Materials Research
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• v.26 no.6
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• pp.347-352
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• 2016

ZnO with wurtzite structure has a wide band gap of 3.37 eV. Because ZnO has a direct band gap and a large exciton binding energy, it has higher optical efficiency and thermal stability than the GaN material of blue light emitting devices. To fabricate ZnO devices with optical and thermal advantages, n-type and p-type doping are needed. Many research groups have devoted themselves to fabricating stable p-type ZnO. In this study, $As^+$ ion was implanted using an ion implanter to fabricate p-type ZnO. After the ion implant, rapid thermal annealing (RTA) was conducted to activate the arsenic dopants. First, the structural and optical properties of the ZnO thin films were investigated for as-grown, as-implanted, and annealed ZnO using FE-SEM, XRD, and PL, respectively. Then, the structural, optical, and electrical properties of the ZnO thin films, depending on the As ion dose variation and the RTA temperatures, were analyzed using the same methods. In our experiment, p-type ZnO thin films with a hole concentration of $1.263{\times}10^{18}cm^{-3}$ were obtained when the dose of $5{\times}10^{14}$ As $ions/cm^2$ was implanted and the RTA was conducted at $850^{\circ}C$ for 1 min.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.2
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• pp.129-136
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• 1993

The purpose of this study is to evaluate whether the ashed tooth powder is utilized as an alternative material of the implant. For this purpose the author performed the experimental study to investigate the tissue response of sintered toothash and its histocompatibility. Bony defects to expose the body of marrow, $1{\times}1cm$ in size, were created in the right and left mandibular body of mature dog, and then the ashed tooth powders were filled in right side and the blood clot was filled in the left side as an control. The dogs were sacrificed at 4th, 7th, and 16th week after implantation and histologic examination was performed. The results of this study were obtained as follows : 1. Any inflammatory response was not noted after implanting of the ashed tooth powder during the whole experimental period. 2. At 4th week, ashed tooth powders were surrounded by mature connective tissue. And we could observe hydroxyapatite crystal structure within the ashed tooth powder. 3. At 7th week, we could observe that macrophage phagocyted the small granules of ashed tooth powders. 4. At 16th week, the union with host bone by growth of new trabeculae was observed. And there were remnants of ashed tooth power within some of new trabeculae.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8679-8683
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• 2015

Using a surface modification technique, ion beam assisted deposition (IBAD) of Ti thin film it becomes possible to prepare an active ceramic surface to braze $Al_2O_3$-STS304 with conventional Ag-Cu eutectic composition filler metal. Researches on bonding formations at interfaces of ceramic joints were mainly related on the development of filler metals to ceramic, the process parameters, and clarifications of reaction products. From the results, the reactive brazing is a very convenient technique compared to the conventional Mn-Mo method. However melting point of reactive filler is still higher than that of Ag-Cu eutectic and it forms the brittle inter metallic compound. Recently several new approaches are introduced to overcome the main shortcomings of the reactive metal brazing in ceramic-metal, metal vapor vacuum arc ion source was introduced to implant the reactive element directly into the ceramics surface, and sputter deposition with sputter etching for the deposition of active material.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.559-568
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• 1998

direct bone apposition during bone remodelling. To address these problem, we developed a new ceramic, calcium metaphosphate(CMP), and report herein the biologic response to CMP in subcutaneous tissue, muscle and bone. Porous CMP blocks were prepared by condensation of anhydrous $Ca(H_2PO_4)_2$ to form non-crystalline $Ca(PO_3)_2$. Macroporous scaffolds were made using a polyurethane sponge method. CMP block possesses a macroporous structure with approximate pore size range of 0.3-1mm. CMP blocks were implanted in 8mm sized calvarial defect, subcutaneous tissue and muscle of 6 Newzealand White rabbits and histologic observation were performed at 4 and 6 weeks later. CMP blocks in subcutaneous tissue and muscle were well adapted without any adverse tissue reaction and resorbed slowly and spontaneously. Histologic observation of calvarial defect at 4 and 6 weeks revealed that CMP matrix were mingled with and directly apposed to new bone without any intervention of fibrous connective tissue. CMP blocks didn't show any adverse tissue reaction and resorbed spontaneously also in calvarial defect. This result revealed that CMP had a high affinity for bone and was very biocompatible. From this preliminary result, it was suggested that CMP was a promising ceramic as a bone substitute and tissue engineering scaffold for bone formation.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.159-169
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• 1993

The thirty six mandibular second molars, which were extracted because of hopeless tooth due to advanced periodontal disease, were measured the length of mesial and distal root and the distance from cementoenamel junction to root separation. The molars were cross-sectioned every 1.5 milimeter from cementoenamel junction to root apex perpendicular to long axis and each section was photographed, projected and measured with a calibrated Digital Curvi-Meter(Com Curvi-8. Japan). The root surface area (RSA), percentage of the RSA and the linear variation of the RSA were calibrated for each 1. 5 mm section. The results were as follows. 1. The mean length of the roots was 12. 98mm for mesial root, 11.84 mm for distal root. The mesial root was longer than distal root.(p<0.01) 2. The mean distance from the cementoenamel junction to the point at which the root separate from the root trunk was 3.82mm for the buccal furcation and 4.75mm for lingual furcation. The buccal root separation was coronal than the lingual root separation.(p<0.01) 3. The total root surface area was $317.78mm^2$. 4. The mean surface area of the root trunk was $150.06mm^2$ and averaged 42.54% of the total root surface area. 5. The mean root surface area was $88.79\;mm^2$ for the mesial root, $78.93mm^2$ for distal root, The mesial root surface area was wider than the distal root surface area.(p<0.05) 6. In comparision, the mean root trunk surface area of the mandibular 2nd molar was wider than that of mandibular 1st molar(p<0.01), but each root of 2nd molar was smaller than that of 1st molar(p<0.01).

• Journal of Periodontal and Implant Science
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• v.46 no.2
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• pp.107-115
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• 2016

Purpose: The aim of this study was to evaluate and compare tooth surface characteristics in extracted human molars after cervical enamel projections (CEPs) were removed with the use of three rotating instruments. Methods: We classified 60 extracted molars due to periodontal lesion with CEPs into grade I, II, or III, according to the Masters and Hoskins' criteria. Each group contained 20 specimens. Three rotating instruments were used to remove the CEPs: a piezoelectric ultrasonic scaler, a periodontal bur, and a diamond bur. Tooth surface characteristics before and after removal of the projections were then evaluated with scanning electron microscopy (SEM). We analyzed the characteristics of the tooth surfaces with respect to roughness and whether the enamel projections had been completely removed. Results: In SEM images, surfaces treated with the diamond bur were smoothest, but this instrument caused considerable harm to tooth structures near the CEPs. The piezoelectric ultrasonic scaler group produced the roughest surface but caused less harm to the tooth structure near the furcation. In general, the surfaces treated with the periodontal bur were smoother than those treated with the ultrasonic scaler, and the periodontal bur did not invade adjacent tooth structures. Conclusions: For removal of grade II CEPs, the most effective instrument was the diamond bur. However, in removing grade III projections, the diamond bur can destroy both adjacent tooth structures and the periodontal apparatus. In such cases, careful use of the periodontal bur may be an appropriate substitute.

• Archives of Plastic Surgery
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• v.34 no.6
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• pp.685-690
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• 2007

Purpose: Numerous materials, both autologous and nonautologous, have been used for augmentation of sunken areas and each has its own limitations. The ideal material for augmentation should not be absorbed in any manner. This study is designed to assess the survival of $SureDerm^{(R)}$, $Permacol^{(R)}$ graft according to the volume and histologic change. Methods: Twenty four mice, weighing about 50 grams and of 5 weeks of age were used. $SureDerm^{(R)}$ is an acellular dermal matix obtained from human cadeveric skin. $Permacol^{(R)}$ is a porcine derived acellular dermal matrix whose manufacture involves trypsinisation, solvent extraction. Graft pieces standardized to $1{\times}1cm$ size were used in each group. The implanted material were taken 1, 4, 8 and 12 weeks later, respectively. The changes of graft volume during the graft period were measured on initial, 1, 4, 8 and 12 weeks. Results: The initial shape of graft was maintained up to 12 weeks in $Permacol^{(R)}$ graft group and mean survival rate was $80.36{\pm}8.21%$ in $SureDerm^{(R)}$, $89.57{\pm}6.39%$ in $Permacol^{(R)}$(p=0.01). The volume of each graft decreased 29% from initial volume on 12 weeks in $SureDerm^{(R)}$, 18% in $Permacol^{(R)}$. The structure of $Permacol^{(R)}$ remained until 12 week after implantation. Conclusion: Our experimental study suggests that $Permacol^{(R)}$ could be a safe material as an implant for permanent augmentation. However, There are further study remained for antigenicity of these material, and the choice of graft for augmentation should be remained to the clinical situations.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.250-253
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• 2013

In this paper, we fabricated 3D pillar type silicon-oxide-nitride-oxide-silicon (SONOS) devices for high density flash applications. To solve the limitation between erase speed and data retention of the conventional SONOS devices, bandgap-engineered (BE) tunneling oxide of oxide-nitride-oxide configuration is integrated with the 3D structure. In addition, the tunneling oxide is modulated by another method of $N_2$ ion implantation ($N_2$ I/I). The measured data shows that the BE-SONOS device has better electrical characteristics, such as a lower threshold voltage ($V_{\tau}$) of 0.13 V, and a higher $g_{m.max}$ of 18.6 ${\mu}A/V$ and mobility of 27.02 $cm^2/Vs$ than the conventional and $N_2$ I/I SONOS devices. Memory characteristics show that the modulated tunneling oxide devices have fast erase speed. Among the devices, the BE-SONOS device has faster program/erase (P/E) speed, and more stable endurance characteristics, than conventional and $N_2$ I/I devices. From the flicker noise analysis, however, the BE-SONOS device seems to have more interface traps between the tunneling oxide and silicon substrate, which should be considered in designing the process conditions. Finally, 3D structures, such as the pillar type BE-SONOS device, are more suitable for next generation memory devices than other modulated tunneling oxide devices.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.22-31
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• 2013

For the case of test equipments requiring data accuracy, real-time is highly required in acceptance test for performance evaluation of developed weapons. For convenience' sake, test equipments are usually developed using Windows. However Windows does not support real-time in itself. Thus, in this paper, so as to reduce development time and expenses, we design and implement an integrated middleware for real-time device drivers using RTiK-MP. Using DLL, we also support user API's for the sake of development convenience without details of the complex RTiK-MP structure. We evaluate the performance of the proposed integrated middleware using the RDTSC command which returns the number of CPU clock ticks. The evaluation results show that it operates correctly within error ranges in the periods of 1ms and 4ms for the cases of TCP/IP and RS-232, respectively.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.71-74
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• 1994

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony ingrowth and secondary long term fixation. Bone ingrowth depends strongly on relative micromotion and stress distributions at the interface. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone-prosthesis interface, Hence an accurate evaluation of interface behavior and stress/strain fields in the bone implant system may be relevant for better understanding of clinical situations and improving THA design. However, complete evaluation of load transfer in the bone remains difficult to assess experimentally, Hence, recently finite element method (FEM) was introduced in orthopaedic research field to fill the gap due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional numerical finite element model which is composed of totally 1179 elements off and 8 node blick. We also analyzed the micromotions at the bone-stem interface and mechanical behavior of existing bone prosthesis for a loading condition simulating the single leg stance. The result indicates that the values of relative motion for this well fit Multilock stem were $150{\mu}m$ in maximum, $82{\mu}m$ in minimum, and the largest relative motion developed in medial region of proximal femur with anterior-posterior direction. The proximal region of the bone was much larger in motion than the distal region and the stress pattern shows high stress concentration on the cortex near the tip of the stem. These findings indicates that the loading in the proximal femoral bone in the early postoperative situation can produce micromotions on the interface and clinically cementless TEA patient should not be allowed weight bearing strictly early in the postoperative period.