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        검색결과 26

        7.
        2007.10 KCI 등재 구독 인증기관·개인회원 무료
        1'0 develop an effi cient scaffold fo1' t issue-engineered bone 1'egene1'ation, we evaluated fully in terconnected globular porous bisphasic calcium-phosphate ceramics. Materials and Methods: Biphasic HA/TCP cera mic scaffolds having f띠 l y interconnected globular structure with small fenestrations adopting foaming method were p1'epared. They were evaluated by cytotoxici ty‘ cellular attachment. and theil‘ differentiation in vitro and the hi s tocompatibili ty, osteoconductivity. and ectopic os teoinductive capacity in 띠 vo , respectively. They have average 400um s ized spherical pores and ave1'age 100um s ized inter connecting interpores with average 85% porosity. They r evealed comparable compression strength with cancellous bone. They were nontoxic and revealed no noxious effect on cellular proliferation and osteoblastic diffe re ntiation. The cul tured cells on scaffolds were well attacbed and proliferated in multi-layers. The increased surface in fully interconnected globular porous scaffold facilitated osteogenic repair by favored cell ular attachment and osteogenic differentia tion with good osteoconductivity. 1n addition. the scaffold-cell constructs induced favorable ectopic bone formati on These findings suggest that the fully interconnected globular porous biphas ic HA/ß -TCP ceramic scaffold formed by foaming method can be a promising bone substitute and a scaffold fo 1' tissue-engineered bone 1'egeneration
        8.
        2007.10 KCI 등재 구독 인증기관·개인회원 무료
        We evaluated the influence of internal macro- porous structure on tissue-engineered bone regeneration by cOll1paring the effi cien cy of scaffold-cell construct forll1ation and its bone induction activity. T매o types of macro-porous CMP cera rnic blocks having 400 um average pore s ize in an interconnected trabecular framework and interconnected globular structu1'e with small fenestrations were prepa1'ed, adopting sponge method and foaming method. respectively. They ware evaluated by cytotoxicity. cell ular attachment. and t heir differenti ation in vitro and the histocompatibility, osteoconductivity, and ectopic osteoinductive potenetial in vivo, respecti vely. Both scaffolds having either interconnected trabecu lar pOI‘es formed by sponge ll1ethod 0 1' fully interconnected globu lar pores formed by foam-based technology were no cyt otoxic and induced neither an immune nor an infl ammatory response regardless 0 1' geometry and manufacturing methods. The fu lly interconnected globul 81 porous scaffold showed more favora ble compression strength compared to the interconnected trabecualr porous scaffold (8.7 :tO. 5 MPa va 5. 5:t0. 5 MPa) . The increased surface in fully interconnected globular po1'ous scaffold facilitated osteogenic repall‘ by favored cellular attachment and osteogenic differentiation with good osteoconductivity. These results suggest that the fully interconnected globular porous structure be more sui table for both bone s ubstit ute and scaffold for t issue-engineered bone regeneration‘
        12.
        2005.10 KCI 등재 구독 인증기관·개인회원 무료
        Mecke!'s car t ilage is one of the ea rliest structu re to appear in a mandible derived from the lï rst branchi a l a rch and serves as the primorclium I"or the formation 01‘ mandible‘ mall eus. incus. and sphenomandibular li gament However. its direct role a nd the mechanism in mandibular clevelopment a re not well elucidated. 1'0 address t his Issue‘ we observed morphol ogical and histological changes and gene expression patterns in the Mecke!'s cart ilage 01" a cleveloping mouse. I"rom E13.5 to E18.5 embryos. using skeletal preparation samples a ncl routinely prepa red s lide secti ons for light mi croscopic observation in various sectional planes. The following methods were per |‘ ormecl : H&E staining I"or general hi st이 og i cal observation ‘ Von Kossafor detection of minerali zation. TRAP activ ity staining for locali zaLion 01’ osteoclastic cell s. immunohistochemistry for !Iα@-1 a ncl -9 forevaluati on of enzy matic activity 01" osteoclasLic cell s. a ncl in situ hybricli zation for detection of collagen type 1. Il. ancl X mRNA ex presslon‘ respecLively. AL E1 3.5 Mec kel's cartilage appeared as a V-shaped rod fused a t the micl line and thin minera li zed ma ndibular buccal plaLe was I"ormed lateral to. and at some clistance from. Meckel’s carti lage in an intramembranous ossi lïcation mocle. WiLh the progression of tooth development. t he Meckel’s in carti lage adjacent incisors revealecl hyperLrophi c chonclrocyte di ff"er entiation with minerali zation of the chondroid matrix. The Meckel’s car Li lage was replacecl with bone by o~ L eoc l asLs . showing strong immunoreact ivity for MMP- l ancl -9 from E16 5 Wi Lh ti me‘ Lhis bony replacement of Meckel's cartilage in an endochondral ossification mode was ex Lenclecl up Lo the mid-porLion of Lhe molar sockets til l EI8.5. The bony replacement of minera li zed hypertrophic chondrocyte zone expressing X collagen mHNA conLri buted to the formation of thick mandibular lingual plate . 1'hese f"i ndings suggesL LhaL mandibular formalion and development is closely relatecl with not only Mecke!'s carLi lage. buL also wiLh Lhc developing LooLh. and thaL C'erLai n in f"l uence from the developing tooth may play a role in detcrmin in g Lhe faLc of Meckel’s ca rLi lage cluring ma ndi bular development.
        13.
        2004.09 구독 인증기관 무료, 개인회원 유료
        PKC는 그들의 cofactor-requirments에 따라 cPKC, nPKC 그리고 aPKC, 3그룹으로 나어진다. 마우스 난 성숙과정에 있어서 cPKC 및 nPKC의 activators인 PMA의 영향에 대한 많은 결과가 보고되었다. 그러나 각각의 그룹에 대한 차별화된 영향에 대하여는 밝혀져 있지 않다. Mezerein의 analog인 thymeleatoxin은 cPKC의 특이적인 activator로 보고되어져 있다. 본 연구에서는 specific cPKC activator인 thymeleatoxin의 마우스 난 성숙과정에의 영향을 제1감수분열 재개 능(germinal vesicle break down, GVBD)과 제1 극체 형성 능(1st polar body extrusion)을 조사하여 cPKC및 nPKC activator인 PMA와 비교 검토하였다. 그 결과 GVBD IC50는 thymeleatoxin에서 ~400nM, PMA에서는 ~50nM이었으며, 제1극체 방출의 IC50는 thymeleatoxin에서 ~200nM, PMA에서는 ~20nM이었다. 이들 결과는 Thymeleatoxin의 GVBD나 1st polar body extrusion 저해효과가 PMA에 비하여 1/8~1/10인 것으로 나타났다. 이들 결과는 GVBD나 제1극체 형성을 포함하는 난 성숙과정에서 cPKC보다 상대적으로 nPKC의 관여가 깊음을 보여 준다.
        3,000원
        14.
        2017.11 서비스 종료(열람 제한)
        Depending on the steam pressure and temperature balance, it is possible to increase the power generation efficiency of the steam turbine by increasing the heat loss of the turbine by increasing the temperature and pressure. As the high temperature and high pressure increase, the boiler main steam amount is reduced by about 10%, but the increase rate of the heat drop is larger than the decrease rate of the steam flow rate, leading to improvement of power generation efficiency. Utilizing the US Department of Energy Steam Turbine Calculator, we calculated the electricity produced by steam temperature and pressure changes. In this study, the steam temperature was increased from 50℃ to 500℃ at the steam temperature of 20 kg/cm²×300℃, and increased by 10 kg/cm² at the pressure of 20 kg/cm² at the pressure of 60 kg/cm² to investigate the changes in electricity production. Electricity production increased with increasing temperature and pressure. The electricity production was increased by 40.11% at 40 kg/cm²×400℃ and 75.56% at 60 kg/cm²×500℃ compared to the standard condition of 20 kg/cm²×300℃ for comparison.
        15.
        2017.11 서비스 종료(열람 제한)
        Energy can be reduced by reducing the exhaust gas temperature at the catalyst inlet and reducing or not using the amount of steam to reheat the exhaust gas. At this time, it is a method to improve the power generation efficiency by using the saved energy for power generation. When the exhaust gas temperature at the inlet of the catalytic reaction tower is operated at about 210℃, it is necessary to increase the temperature of the flue gas downstream of the bag filter at 165℃ to 45℃ to 210℃ required for the catalytic reaction. In the case of low temperature catalyst application, the temperature required for the catalytic reaction tower may be 185℃ and the temperature may be raised only 20℃. Therefore, the amount of steam for heating can be reduced. If the exhaust gas temperature of the bag filter inlet can be increased to 190℃, it can be combined with the low-temperature catalyst to reduce the energy consumed by removing exhaust gas ash. On the other hand, since the high-pressure steam is used as the heat source for reheating the exhaust gas, the reheating temperature is limited. According to such conditions, the exhaust gas temperature at the inlet of the catalytic reaction tower is often designed at about 200 to 220℃.
        16.
        2017.11 서비스 종료(열람 제한)
        Even if the amount of exhaust gas is the same, it is possible to reduce the exhaust gas exit heat at the outlet of the boiler facility by lowering the outlet temperature of the economizer, so that it is possible to increase the heat quantity recovered from the boiler facility. There are many cases where the existing facility adopts 220~250℃ as the design value of the exhaust gas temperature at the exit of the economizer. However, in recent years, there has been a case of cooling and recovering heat to 200℃ or less from the viewpoint of active heat recovery. The amount of combustion exhaust gas is reduced by reducing the amount of combustion air supplied to the incinerator, and the amount of heat exhausted from the boiler facility is reduced, thereby improving the boiler efficiency. The holding energy of the combustion exhaust gas is the product of the exhaust gas amount and the specific heat and the temperature. In order to recover more heat from the combustion exhaust gas, not only the heat loss in the boiler facility is reduced, but also the heat radiated from the boiler facility is reduced. It is effective to reduce the exhaust gas temperature at the outlet of the heat recovery equipment and reduce the amount of exhaust gas in order to reduce the amount of exhaust heat of the exhaust gas. Even if the exhaust gas temperature at the outlet of the economizer is the same, the amount of exhaust gas discharged at the boiler facility outlet is reduced by reducing the amount of exhaust gas, and an increase in the recovered heat quantity at the boiler is expected.
        17.
        2017.11 서비스 종료(열람 제한)
        Persistent organic pollutants are highly toxic, stay in the environment for a long time, accumulate in the body according to the food chain, and cause damage not only to the area where they occur but also to other areas beyond the border. Parties to the Convention, as well as Korea, are obliged to carry out various efforts to control, reduce or eliminate sources of POPs in accordance with the national implementation plan. In addition, national efforts to limit the production, distribution and use of persistent organic pollutants and the current state of domestic pollution and emissions should be submitted every five years. A flame retardant is a polymeric material with a property that is easy to burn, and it lowers the ignition point by adding a compound having a large flame retarding effect such as halogen, phosphorus, and a nitrogen metal compound. Among them, chlorine-based flame retardants classified as halogen-based are used for suppressing ignition of combustible organic materials including plastics, furniture, textiles, clothing, and electronic products. It is also used as an alternative to brominated flame retardants, causing mutations in carcinogenic substances, hormone destruction, and nervous system damage. In the case of waste containing chlorine-based flame retardants in Korea, the methods and standards for disposal of waste are not specified. The highest SCCP values were 4,253.09 mg/kg for polyurethane foam, 628.29 mg/kg for mobile phone case and 341.91 mg/kg for flame retardant rubber sheet. In the case of car seats no SCCPs were detected, and TCEP was detected at 512. 66 mg/kg, exceeding the EU limit of 5 mg/kg. However, other chlorinated flame retardants TDCP and TDCPP were not detected in all samples.
        18.
        2017.11 서비스 종료(열람 제한)
        Annex A and Annex B of the Stockholm Convention define POPs as unintentional releases to Annex C, as well as organochlorine pesticides, polychlorinated biphenyls and hexachlorobenzen which are intentionally produced and used. These pesticides are very stable in the atmosphere due to insecticides, fungicides, herbicides, etc., and are likely to accumulate in living organisms due to residues in crops. There are 15 substances listed in POPs. These materials are widely used due to their high chemical stability, low solubility in water, high volatility, strong insecticidal effect and relatively low production costs. Aldrin-containing pesticides are known to have a combustion method for incineration in a chemical incinerator equipped with a reheat-burner device and a gas scrubber, and a solidification isolation method for solidifying and filling with cement mixed with a combustible material in waste treatment. In the case of solid-phase pesticides, HCB was 421.8 ng/g, Endosolfan-2 73.044 ng/g, PeCB 53.972 ng/g and Endosolfan-1 43.649 ng/g. In the case of liquid pesticides, HCB concentration was the highest at 167.489 ng/g similar to that of the solid phase, followed by PeCB at 23.462 ng/g. B-HCH, g-HCH, d-HCH and the like were detected as a small amount of other substances. It is judged that it is not necessary to set separate operating conditions or preventive facility standards since the material is decomposed sufficiently at 850℃ or more. However, considering the possibility of dioxin or unintentional persistent organic pollutants, it is considered appropriate to operate at above 1,100℃.
        19.
        2017.05 서비스 종료(열람 제한)
        Elemental analysis, calorific value, etc. were measured to obtain basic information such as decomposition temperature and required oxygen amount for thermal treatment of waste containing chlorine-based flame retardant. Moisture, flammability and ash content of polyurethane foam were high in water, flammable rubber sheet in case of ash and flame retardant rubber sheet in case of ash. As a result of thermogravimetric analysis, the weight change in the range of 300 ~ 600 ℃ was large. The content of chlorinated flame retardant agent was analyzed to be higher than that of polyurethane foam (4,253.09 mg/kg), cell phone case (cloth, leather) 628.29 mg/kg and flame retardant rubber sheet 341.91 mg/kg. Chlorinated flame retardant materials, TDCP and TDCPP, were not detected in all samples. As a result of the decomposition tests for chlorine-based flame retardants at 850 ℃ and 1,100 ℃, chlorine-based flame retardant components were not detected in exhaust gas at all at 1,100 ℃ as well as at 850 ℃ in all samples including mobile phone cases, flame retardant rubber sheets and car seats. As a result of calculating the conversion rate for total chlorine value, it showed more than 99% even at 850 ℃ as well as at 1,100 ℃. Considering the decomposition rate in laboratory experiments of chlorine-based flame retardant-containing wastes, it is considered possible to incinerate at a scale of 2 ton/hour or more, which is the existing incineration facility. It is judged that it is not necessary to set separate operating conditions or preventive facility standards since the material is decomposed sufficiently at 850 ℃ or more. However, considering the possibility of dioxin or unintentional persistent organic pollutants, it is considered appropriate to operate at above 1,100 ℃.
        20.
        2017.05 서비스 종료(열람 제한)
        As a result of analyzing the contents of organic chlorine pesticide-containing wastes, HCB 421.8 ng/g, Endosolfan- 2 73.044 ng/g, PeCB 53.972 ng/g, Endosolphan-1 43.649 ng/g respectively. In the case of liquid pesticides, the HCB concentration was the highest at 167.489 ng/g, similar to that of the solid phase, followed by PeCB at 23.462 ng/g. As a result of decomposition experiments on total OCPs among the pesticide liquid and solid phase components, initial concentrations were 597.384 ng/L for liquid pesticides and 198.176 ng/L for solid pesticides. However, the final effluent gas after decomposition showed a decomposition rate of more than 99.99% at a minimum of 0.005 ng/L and a maximum of 0.055 ng/L. Degradation test results for 25 species of OCPs such as PeCB, HCB, and Endosolfan for pesticide solid phase and liquid phase at reaction temperatures of 850℃ and 1,100℃. Of the 25 OCPs in the exhaust gas, trace amounts of PeCB and HCB were detected in the range of 0.006 to 1.025 ng/L at 1,100 ℃ and 850 ℃, and 23 OCPs were not detected. In the case of pesticides, the method of high temperature incineration and high temperature melting is proposed as the designated waste, but detailed methods of treatment conditions such as incineration conditions are not presented. Organochlorine pesticides were decomposed smoothly at 850 ℃ as well as incineration temperature of 1,100 ℃. However, since the dioxin concentration in exhaust gas exceeds 850 ℃, it is safe to operate at more than 1,100 ℃ in order to prevent the possibility of dioxin in advance.
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