• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.700-708
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• 2001

Traumatic injuries in young patients can result in the interruption of the development of the incompletely formed roots. In teeth with incomplete root-end formation and necrotic pulps, the root canals must be completely debrided. Because of a lack of an apical stop and the presence of thin and fragile walls in these teeth, it is imperative to perform apexification to obtain an adequate apical seal. Calcium hydroxide has become the material of choice for apexification. Despite its popularity for the apexification procedure, calcium hydroxide therapy has some inherent disadvantages that include variablility of treatment time, unpredictability of apical closure, difficulty in patient follow-up, and delayed treatment. An alternative treatment to long-term apexification procedure is the use of an artificial apical barrier that allows immediate obturation of the canal. MTA(Mineral Trioxide Aggregate) is a powder consisting of fine hydrophilic particles of tricalcium silicate, tricalcium aluminate, tricalcium oxide and silicate oxide. MTA has a pH of 12.5 after setting, similar to calcium hydroxide. This may impart some antimicrobial properties. MTA has low solubility and a radiopacity slightly eater than that of dentin. Also, MTA leaked significantly less than other materials and induced hard-tissue formation more than other materials.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.178-182
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• 2005

Basic optimal extraction condition and stability data were determined for prediction of usefulness of olive leaf as functional food material. Solid contents of olive leaf extracts increased with increasing extraction temperature and ethanol content, and was the highest (38%) under $85^{\circ}C$, 80% ethanol, and 5 hr treatment conditions, Total phenol contents and electron-donating abilities of olive leaf extracts also increased with Increasing ethanol content, and were the highest under $25^{\circ}C$, 80% ethanol, and 1 hr treatment conditions, then slightly decreased during storage at $25,\;55,\;and\;85^{\circ}C$. Olive leaf extract showed high stability under acidic storage condition, while low under alkalic condition.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.49-55
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• 2018

Under the era of energy crisis, hydrogen energy is considered as one of the most potential alternative energies. Liquid hydrogen has much higher energy density per unit volume than gas hydrogen and is counted as the excellent energy storage method. In this study, Navier-Stokes equations based on 2-phase model were solved by using a computational fluid dynamics program and the liquefaction process of gaseous hydrogen passing through a cryogenic cooling tube was analyzed. The copper with high thermal conductivity was assumed as the material for cryogenic cooling tube. For different inlet velocities of 5 m/s, 10 m/s and 20 m/s for hydrogen gas, the distributions of fluid temperature, axial and radial velocities, and volume fractions of gas and liquid hydrogens were compared. These research results are expected to be used as basic data for the future design and fabrication of cryogenic cooling tube to transform the hydrogen gas into liquid hydrogen.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1161-1170
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• 2014

In global competition like today, intellectual property of novel areas such as traditional knowledge, traditional creation, hereditary resource, etc. are perceived as important resources. Therefore making solid competitive power in overall knowledge resources like cultural contents, brand, design etc. in nation is a pressing question. Accordingly in this study, to prepare for intellectual property rights dispute and advantage-sharing problem that would be variously derived from the Nagoya Protocol which will come into force after 2014, this research selected 200 knowledge of middle region in Korea from 2,047 literal and 931 oral knowledge using preconditioning process. The order of priority of top 50 of them was ranked by a quantitative research method, the Delphi survey. Among them, 30 was literal traditional knowledge and 20 was oral traditional knowledge. Result of this research could be used later as basic material for qualitative researches like the focus group interviewing. Furthermore in this paper is meaningful; the selected traditional knowledge can contribute remarkably to traditional biologic knowledge resource in nation which can be acknowledged in international society, announcing validity (hold precedence for patent) later on.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.20-28
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• 2006

Statement of problem: The titanium has advantages of a high biocompatibility, a corrosion resistence, low density, and cheep price, so it is focused as a substituted alloy But it is quite difficult to cast with the tranditional method due to the high melting point, reacivity with element at, elevated temperature. By using the CAD-CAM system for the crown construction, it is possible to reduce the errors while proceeding the wax-up, investing, and casting procedure Purpose: The purposes of this study were to measure the marginal adaptation of the casting titanium coping and machine-milled titanium coping according to the casting methods and the marginal configurations. Material and method: The marginal configurations were used chamfer shoulder, and beveled shoulder. The total 30 copings were used, and these are divided into 6 groups according to the manufacturing method and marginal configuration. The gap between margin of the model and the restoration was measured with 3-dimensional measuring microscope. Results: The following results were obtained; 1. casting gold coping demonstrated the best marginal seal, followed by casting titanium coping finally machine-milled titanium copings. 2. In casting titanium coping, chamfer demonstrated the best marginal seal, followed by shoulder and beveled shoulder. There was no significantly difference in shoulder and beveled shoulder. But all margin form has clinically acceptable 3. In machine-milled titanium copings, chamfer demonstrated the best marginal seal, followed by shoulder and beveled shoulder. Beveled shoulder show large and uneven marginal gap Conclusions: Above result revealed that marginal adaptation of the titanim coping is avail able in the clinical range, it can be used as an alternative metal and it is prefered especially in chamfer or shoulder margin during implant superstructure fabrication. But there should be more research on machine-milled titanium in order to use it in the clinics.

• Economic and Environmental Geology
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• v.49 no.3
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• pp.213-224
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• 2016

Non-conventional resource and alternative energy were researched for predicting oil peak. In this study, one of many non-conventional resources, specifically oil-sands, was investigated due to the increasing interest of oil-sands plant modularization in permaforst areas for reducing the construction periods through modular transportation while limiting local construction workers. Hence, tehcnological trends were analyzed for oil-sand plant modularization. Data used were between 1994 and 2015 for patent analysis while targets included Korea, US, Japan, Europe and Canada. Technology classification system consisted of mining, steam assisted gravity drainage(SAGD), separation/upgrading/tailors ponds, module design/packaging, module transportation and material/maintenance. Result of patent analysis, patent application accounts 89% in US and Canada. The main competitive companies were Shell, Suncor and Exxon-mobil. Unlike other oil developments, oil-sands have a long-term stable production characteristic, hence, it is important to ensure the competitiveness of oil-sands for obtaining a patent in the long run.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.26-34
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• 2014

Due to the rapid energy consumption and fossil fuel abundance reduction, the world is progressively in need of alternative and renewable energy sources such as biodiesel. Biodiesel from microalgae offers high hopes to the scientific world for its potential as well as its non-competition with arable lands. Taking consideration to reduce the cost of production as well as to attain twin environmental goals of treatment and use of animal waste material the microalgal cultivation using piggery manure has been tested in this study. Unialgal strains such as Chlorella sp. JK2, Scenedesmus sp. JK10, and an indigenous mixed microalgal culture CSS were cultured for 20 days in diluted piggery manure using Small Scale Raceway Pond (SSRP). Biomass production and lipid productivity of CSS were $1.19{\pm}0.09gL^{-1}$, $12.44{\pm}0.38mgL^{-1}day^{-1}$, respectively and almost twice that of unialgal strains. Also, total nitrogen and total phosphorus removal efficiencies of CSS was 93.6% and 98.5% respectively and 30% higher removal efficiency compared to the use of unialgal strains. These results indicate that the piggery manure can provide microalgae necessary nitrogen and phosphorus for growth thereby effectively treating the manure. In addition, overall cost of microalgal cultivation and subsequently biodiesel production would be significantly reduced.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.57-65
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• 2013

The development of the oil refining industry has resulted in an annual 120 million tons of sulphur, which is a by-product of the desulphurization process. To exploit this abundance, the applications of sulphur must be expanded. as excellent durability of reuse of leftover sulphur which has high potential for utilization in construction materials, the study is actively in progress. Meanwhile, there has been active research on semi-rigid pavements that draw on the strengths and overcome the weaknesses of asphalt and concrete pavements. Acrylate is used to prevent cracking but involves a high cost, thus, an alternative material is required. As such, this study presents methods on the reuse of leftover sulphur and examines the engineering performance of grout containing sulfur polymer emulsion (SPE) for use in semi-rigid pavements. Our analysis shows that grout in which 30% of acrylate is replaced with SPE has superior properties in terms of time of flow and strength compared to regular grout. However, performance declined when more than 50% of acrylate was replaced by SPE, indicating that the optimum replacement level is 30%. Through SEM analysis, we found that grout with utra harding cement in this study at three hours had similar hydration properties to that of Type 1 Ordinary Portland Cement (OPC) at seven days, and maintained the properties regardless of grout containing SPE. OPC and grout with a replacement level of 30% displayed similar levels of chloride invasion resistance, whereas grout without SPE was far less resistant. Within the scope of this paper, the optimum replacement level of acrylate with SPE was found to be 30% in consideration of various properties such as time of flow, strength, and chloride invasion resistance.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.469-472
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• 2010

Purpose: Aplasia Cutis Congenita (ACC) is a rare disease characterized by the focal defect of the skin at birth, frequently involving scalp, but it may affect any region of the body. There are no etiology known but some conditions such as intrauterine vascular ischemia, amniotic adherences and viral infections are associated. The ideal treatment for the ACC is not known. Superficial and relatively small sized defects (< $3{\times}5\;cm$) may heal spontaneously and large defects related with risks of infection and bleeding may require aggressive surgical treatment. Hyalomatrix$^{(R)}$ is a bilayer of an esterified hyaluronan scaffold beneath a silicone membrane. It has been used as a temporary dermal substitute to cover deep thickness skin defect and has physiological functions derive from the structural role in extracellular matrix and interaction with cell surface receptor. This material has been used for the wound bed pre-treatment for skin graft to follow and especially in uncooperative patient, like a newborn, this could be a efficient and aseptic way of promoting granulation without daily irritative wound care. For this reason, using Hyalomatrix$^{(R)}$ for the treatment of ACC was preferred in this paper. Methods: We report a case of a newborn with ACC of the vertex scalp and non-ossified partial skull defect. The large sized skin and skull defect ($6{\times}6\;cm$) was found with intact dura mater. No other complications such as bleeding or abnormal neurologic sign were accompanied. Escharectomy was performed and Hyalomatrix$^{(R)}$ was applied for the protection and the induction of acute wound healing for 3 months before the split-thickness skin graft. During the 3 months period, the dressing was renewed in aseptic technique for every 3 weeks. The skin graft was achieved on the healthy granulation bed. Results: The operative procedure was uneventful without necessity of blood transfusion. Postoperative physical examination revealed no additional abnormalities. Regular wound management was performed in out-patient clinic and the grafted skin was taken completely. No other problems developed during follow-up. Conclusion: Hyalomatrix$^{(R)}$ provides protective and favorable environment for wound healing. The combination of the use of Hyalomatrix$^{(R)}$ and the skin graft will be a good alternative for the ACC patients with relatively large defect on vertex.

• Journal of Chest Surgery
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• v.33 no.2
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• pp.146-150
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• 2000

background: The prognosis after an aortic valve replacment can be affected significantly by the transprosthetic pressure gradient which is determined mainly by the size of the patients body and the prosthesis used. We analyzed the hemodynamic feature of two relatively new prosthese the ATS and the evensized Medtronic-Hall(M-H) valves by measuring the transprosthetic pressure gradient in the cases where small sizes (23mm or smaller) were used. Material and method: There were 94 patients who received whom aortic valve replacement with prosthesis smaller than 23 mm from October 1994 to June 1998. In these patients the transprosthetic pressure gradient clalculated from the pressure half time during postoperative Dopper echocardiographic examination was compared between the prostheses of different sizes. The body surface area of each patient was also taken into consideration. result: The mean pressure gradient and body surface area in each group were 21.7$\pm$10.2 mmHg and 1.52$\pm$0.14m2 in ATS 19mm 11.4$\pm$6.5 mmHg and 1,57$\pm$0.20m2 in M-H 20mm 15.2$\pm$6.3 mmHg and 1.54$\pm$0.13m2 in ATS 21mm 9.3$\pm$2.5 mmHg and 1.63 $\pm$0.14m2 in M-H 22 mm and 12.9$\pm$5.3 mmHg and 1.69$\pm$0.13m2 in ATS 23mm. Conclusion: The 19mm ATS prosthesis showed significant trasprosthetic pressure gradient which is similar to the values previously reported with other bileaflet prosthesesm Close follow-up was needed in terms of exercise capacity and change in left ventiricular geometry. In patients with small aortic valve annulus the 20mm M-H valve is recomendable as an alternative to 19mm bileaflet valves because it has less pressure gradient with similar outer diameter.