• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.193-200
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• 2011

A BOR(Boil-Off Rate) prediction model for the NO96 membrane-type LNG insulation containment filled with superlite powders during laden voyage is presented in this paper. Finite element model for the unsteady-state heat transfer analysis is constructed by considering the air and water conditions and by employing the homogenization method to simplify the complex insulation material composition. BOR is evaluated in terms of the total amount of heat invaded into LNGCC and its variation to the major variables is investigated by the parametric heat transfer analysis. Based upon the parametric results, a BOR prediction model which is in function of the LNG tank size, the insulation layer thickness and the powder thermal conductivity is derived. Through the verification experiment, the accuracy of the derived prediction model is justified such that the maximum relative difference is less than 1% when compared with the direct numerical estimation using the FEM analysis.

• Polymer(Korea)
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• v.30 no.6
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• pp.471-477
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• 2006

Ion exchange metal composite(IPMC) has toughness equivalent to the range of human's muscle, transformation-actuation force by relatively low voltage and the fast response time. Thus, as a new method for preparing thicker IPMC, the solution casting method to make the films of various thicknesses out of liquid nation was attempted in this study. To reduce the surface resistance of electrode, the first plated electrode prepared by Oguro method was replated with Au and Ir using ion beam assisted deposition(IBAD). The microstructures of electrode surfaces before and after IBAD plating were investigated using SEM. The change of water and ion-conductivity in IPMC were measured under applied voltage. The displacement and driving force of IPMCs with various thicknesses were measured to evaluate the driving properties.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.186-191
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• 1999

The three speices of miroalgae (Chlorella vulgaris, Dunaliella salina and Porphyridium purpureum) were immobilized in Ca-alginate capsules as a basic study for development of economic cultivation process, and then were cultivated in an air-bubble column bioreactor. Under the batch culture of aerobic conditions, the thickness of the capsule membrane and $CO_2$ supply did not affect the growth of the immobilized microalga, Chlorella vulgaris. Cell concentration of immobilized microalgae in the capsule was higher than those of imobilized microalgae in beads and free cells. The cell concentration of microencapsulated Dunaliella salina was greater about 5 times than that of free cells. Based on these results, it is concluded that the application of microencapsulation technology to the culture of microalgae was an effective method for high-density cultivation.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.605-621
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• 1993

The gingival hyperplasia refers to an increase in the size of the gingival tissue produced by an increase in the number of its component cells. In order to investigate the cellular change in epithelium and subepithelial tissue of noninflammatory gingival hyperplasia, the gingival tissues were surgically obtained from the patients with dilantin gingival hyperplasia and idiopathic gingival hyperplasia. The excised tissue samples were fixed in neutral formalin for 6-24 hours, embedded with paraffin, sectioned at $4-6{\mu}m$ in thickness, mounted on glass slides coated with 3-aminopropyltriethoxysilane(Sigma Chemical Co., St. Louis, MO, U.S.A.) and immunocytochemically processed by Avidin-Biotin peroxidase complex method for detecting proliferating cell nuclear antigen, tenascin and collagen type IV. Monoclonal mouse anti-human PCNA antibody(Oncogene Science, Uniondale, NY, U.S.A., 1 : 250,000), monoclonal mouse anti-human tenascin antibody(Chemicon-International Inc., Temecula, CA, U.S.A., 1:5,000), and monoclonal mouse anti-human collagen type IV(Dakopatts, Glostrup, Denmark, 1: 50) were used as primary antibodies. The results were as follows: 1. In non-inflammatory gingival hyperplasia, the positive reaction to proliferating cell nuclear antigen was localized in the basal cell layer of gingival epithelium and well-developed rete pegs. 2. The positive reaction to tenascin was shown in the connective tissue subjacent to basament membrane of gingival tissue, and especially strong positive reaction was noted in the tip portion of connective tissue projections. 3. The positive reaction to collagen type IV was localized along the basement membranes of gingival epithelium and blood vessels. The results suggest that connective tissue enlargement may affect the proliferation of gingival epithelium.

• Archives of Craniofacial Surgery
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• v.13 no.1
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• pp.76-79
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• 2012

Purpose: Sebaceous epithelioma (sebaceoma) is a benign tumor with sebaceous differentiation. It presents primarily as a yellowish papule or nodule on the face and scalp. It must be differentiated from basal cell carcinoma and other appendageal tumors. We report a giant sebaceous epithelioma on the scalp and describe the immunohistochemical character of the cells in sebaceous epithelioma to epithelial membrane antigen (EMA). Methods: A 55-year-old-man who presented with 5-cm-diameter 2-cm-height, round shape exophytic ulcerated tumor on his head presented for treatment. The patient had noticed the lesion 40 years prior as a small yellowish plaque and 18 months ago, the plaque started to grow progressively larger. We excised the lesion with 1 cm resection margin, considering the possibility of malignancy because this lesion grossly resembled basal cell carcinoma (BCC). The defect was repaired with the use of a splitthickness skin graft. Results: When we excised the lesion, the margin was clear. Histology showed nodules that consisted of an admixture of basaloid cells and mature adipocytes lacking an organized lobular architecture. Strong expression of EMA on mature adipose cells confirmed the differential diagnosis from BCC with sebaceous differentiation because of the absence of a nuclear palisade pattern and cleft-like spaces on the hematoxylin and eosin (H&E) section. Conclusion: We treated the giant sebaceous epithelioma on the scalp with surgical excision and a split-thickness skin graft. It is important to know that the diagnosis of sebaceous epithelioma should be made based on the histologic pattern of the H&E section. Immunohistochemistry with EMA can help to confirm the differential diagnosis between sebaceous epithelioma and BCC.

• Journal of Korean Association for Spatial Structures
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• v.12 no.1
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• pp.87-98
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• 2012

In this study, mechanical role of edge beams in the gabled hyperbolic paraboloid shells was investigated through the comparisons of Finite element(FE) analysis results between the shells structures with and without edge beams. In addition, the effects of roof slope was studied. FE analysis showed that roof loads was directly transferred to the supports at corners by the arch action in the diagonal direction of the shells, thus, less member forces in the edge and ridge beams but higher stresses near supports were estimated than those from the membrane theory. When the edge beams were removed, stress concentration in the shells near the supports and the deflections along the shell edge were increased. Such phenomenon were intensified as the roof slope decrease. Thus, in gable hyperbolic paraboloid shell, the thickness of the shell near supports needs to be increased and careful investigation should be made in the cases when the roof height is low and/or the edge beams are removed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.11-19
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• 2003

A micro sensor array with 4 discrete sensors integrated on a microhotplate was developed for identifying the kinds and quantities of explosive gases. The sensor array consisited of four tin oxide-based thin films with the high and broad sensitivity to the tested explosive gases and uniform thermal distribution on the plate. The microhotplate, using silicon substrate with N/O/N membrane, dangling in air by Al bonding wires, and controlling the thickness by chemical mechanical process (CMP), has been designed and fabricated. By employing the sensitivity signal of the sensor array at 40$0^{\circ}C$, we could reliably classily the kinds and quantities of the explosive gases like butan, propane, LPG, and carbon monoxide within the range of threshold limit values (TLVs), employing principal component analysis (PCA).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.9-14
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• 2004

In this study, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ ammonium persulfate(AP)/isopropyl alcohol(IPA) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-unifonnity exists on the etched surface because of formation of hillocks on the (100) surface. The addition of IPA to TMAH solution leads to smoother etched surfaces but, makes the Si etch rate lower. However, with the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square membranes of 20${\mu}{\textrm}{m}$ thickness and l00-400${\mu}{\textrm}{m}$ one-side length were fabricated successfully by applying optimum Si etching conditions of TMAH/AP solutions.

• Journal of Periodontal and Implant Science
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• v.46 no.1
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• pp.57-69
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• 2016

Purpose: The aim of this pilot study was to determine the osteoconductivity and dimensional stability of augmented sinuses using different ratios of biphasic calcium phosphate (BCP) in a rabbit sinus model. Methods: Each sinus of New Zealand white rabbits (2.5-3.5 kg) was assigned to one of two groups: BCP with a hydroxyapatite to ${\beta}$-tricalcium phosphate (HA:${\beta}$-TCP) ratio of 70:30 (group TCP30) and BCP with an HA:${\beta}$-TCP ratio of 30:70 (group TCP70). After preparing a window in the antral wall of a sinus, the Schneiderian membrane was elevated, and the applicable material was grafted. A fluorochrome calcein green was injected five days before euthanizing the animals at four months post-surgery. The specimens were analyzed histologically, histomorphometrically, and by using micro-computed tomography (micro-CT). Results: Micro-CT analysis revealed that the total augmented volume and the new bone volume did not differ significantly between the two groups whereas the resorption of materials was greater in the TCP70 group. The trabecular thickness, number, and separation also did not differ significantly between the two groups. Histomorphometrically, the areas of total augmentation, new bone, and residual material, as well as the ratio of new-bone-material contact did not differ significantly between the groups. Histologically, the residual particles were more scattered in the TCP70 group than in the TCP30 group. The fluorescence of the calcein green did not differ notably between the two groups. Conclusions: The osteoconductivity and dimensional stability of the two BCPs with different ratios tested in this study were comparable after four months of healing. Therefore, we conclude that both BCPs show promise as a bone substitute for sinus augmentation.

• Archives of Pharmacal Research
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• v.18 no.3
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• pp.183-188
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• 1995

Polymeric reinforcement and coatings of alginate beads were carried out to control the release rate of drug from alginate beads. A poorly water-soluble ibuprofen (IPF) was selected as a model drug. A commercially available $Eudragit^{\circledR}$ RS100 was also used as a polymer. Effects of polymeric contents, the presence of plasticizers and amount of drug loading on the release rate of drug were investigated. The release rate of drug from alginate beads in the simulated gastric fluid did not occur within 2 h but released immediately when dissolution media were switched to the simulated intestinal fluid. No significant difference of release rate from polymer-reinforced alginate bead without plasticizers was observed when compared to plain (simple) beads. However, the release rate of drug from polymer-reinforced alginate beads was further sustained and retarded when aluminium tristearate (AT) as a plasticizer was added to polymer. However, polyethylene glycol 400 (PEG400) did not change the release rate of drug from alginate beads although PEG400 was used to improve dispersion of polymer and sodium alginate, and plasticize $Eudragit^{\circledR}$ RS100 polymer. The presence of plasticizer was crucial to reinforce alginate gel matrices using a polymer. As the amount of drug loading increased, the release rate of drug increased as a result of decreasing effects of polymer contents in matrices. The significantly sustained release of drug from polymer-coated alginate beads occurred as the amount of polymer increased because the thickness of coated membrane increased so that cracks and pores of the outer surface of alginate beads could be reduced. The sustained and retarded action of polymer-reinforced and coated beads may result from the disturbance of swelling and erosion (disintegration) of alginate beads. From these findings, polymeric-reinforcement and coatings of alginate gel beads can provide an advanced delivery system by retarding the release rate of various drugs.