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        검색결과 45

        1.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acidbase titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.
        4,300원
        2.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sugarcane bagasse has been used as a substrate for the development of microporous nano-activated carbons for the treatment and elimination of dissolved materials from aquatic environment. The activated carbon was produced using chemical activation in one-step method with zinc chloride ( ZnCl2) as the activating agent at a carbonization temperatures range from 500 to 900 °C. The effects of temperature and time of carbonization on the activated carbon product properties were thoroughly studied. The activated carbons that resulted were characterized using the N2 adsorption/desorption isotherms, Brunauer–Emmett–Teller method (BET), pore property analysis, micropore (MP) surface area, t-plot surface area, TGA, FTIR, SEM, TEM, and EDX analyses. The prepared activated carbon’s point of zero charge, Boehm titration process, iodine removal percentage, and methylene blue number were also investigated. The prepared activated carbon’s maximum surface area was achieved using a 2/1 impregnation ratio (dried sugarcane bagasse/ZnCl2) at 600 °C temperature of carbonization and 60 min residence time. 1402.2 m2/ g, 0.6214 and 1.41 cm3/ g, respectively, were the largest surface area, total pore volume, and micropore volume. As the activation temperature increased, the total pore volume increased and the BET study measured a pore diameter of 0.7 nm and a mean pore diameter of 1.77 nm.
        5,700원
        3.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The gas response characteristic toward C2H5OH has been demonstrated in terms of copper-vacancy concentration, hole density, and microstructural factors for undoped/Li(I)-doped CuO thin films prepared by sol-gel method. For the films, both concentrations of intrinsic copper vacancies and electronic holes decrease with increasing calcination temperature from 400 to 500 to 600 oC. Li(I) doping into CuO leads to the reduction of copper-vacancy concentration and the enhancement of hole density. The increase of calcination temperature or Li(I) doping concentration in the film increases both optical band gap energy and Cu2p binding energy, which are characterized by UV-vis-NIR and X-ray photoelectron spectroscopy, respectively. The overall hole density of the film is determined by the offset effect of intrinsic and extrinsic hole densities, which depend on the calcination temperature and the Li(I) doping amount, respectively. The apparent resistance of the film is determined by the concentration of the structural defects such as copper vacancies, Li(I) dopants, and grain boundaries, as well as by the hole density. As a result, it is found that the gas response value of the film sensor is directly proportional to the apparent sensor resistance.
        4,000원
        5.
        2017.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        중저준위 방사성폐기물의 처분안전성 확보와 중저준위 방폐물관리 시행계획에 따른 안정적인 처분시설 개발을 위해 중준위 방사성폐기물 처분농도제한치에 대하여 IAEA 방법론에 따라 고찰하였다. 고찰결과 IAEA 방법론에 따라 도출된 결과는 1단 계 동굴처분시설 중준위 방사성폐기물의 처분농도제한치로 사용하기 부적합하였다. 1단계 동굴처분시설은 다양한 준위 및 여러 종류의 방사성폐기물이 처분 대상이 되나, IAEA 방법론은 본래 천층처분시설의 처분농도제한치를 설정하는 방법으로 서, 단일종류의 방사성폐기물로만 구성된 처분시설의 처분농도제한치를 설정하기 적합하기 때문이었다. 따라서 처분대상 방사성폐기물의 준위별 수량을 고려한 방사능 도출, 이에 대한 시나리오별 평가결과 및 성능목표치를 고려한 1단계 동굴처 분시설 중준위 방사성폐기물 처분농도제한치 산출 방법의 개발 및 적용이 동굴처분시설의 안정적인 운영을 위해 필요하다.
        4,000원
        6.
        2016.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in this paper and the latter in the companion paper. The verification is conducted via geotechnical dynamic centrifuge test in prototype scale. Response of wall stem, ground motions behind the wall obtained from RHA matched pretty well with physical test performed under centrifugal acceleration of 50g. The rigorously verified RHA is used for parametric study to investigate an effect of input earthquake motion selection in the companion paper.
        4,000원
        7.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Makgeolli is a health beneficial food for diabetes compared to other alcoholic beverages. We examined the effect of Makgeolli on blood glucose level and survival rate in a streptozotocin (STZ)-induced diabetic mouse model. We force fed 30 male STZ-induced diabetic ICR mice Makgeolli consisting of 6% alcohol (DM-MAK), 6% ethanol (DM-EtOH), or distilled water (DM-DW) for 4 weeks. In the DM-MAK group, food intake and water intake were higher than those of other groups after 4 weeks. Body weight, however, was not different among the experimental groups. We also found no significant difference in blood glucose level among the experimental groups. In normal ICR mice fed Makgeolli for 1 week, the area of the blood glucose curve was higher than those of other groups fed 6% ethanol, 2% glucose, or distilled water. Survival rates of STZ-induced diabetic mice fed Makgeolli, 6% ethanol, or DW for 4 weeks were 100%, 25%, and 62.5%, respectively. In conclusion, Makgeolli had no beneficial effect on blood glucose in a STZ-induced diabetic mouse model, although their survival rate was high. These results show that Makgeolli has an effect on type 1 diabetes through other mechanisms than blood glucose control.
        4,000원
        9.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As a part of the short-period variability survey (SPVS) at Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of Cyg OB3 association centered on the open cluster NGC 6871. The observations were performed for 18 nights from September 5, 2008 to September 1, 2009. We found 15 short-period variable stars in the region. They are δ Scuti type stars belonging to the local spiral arm, Orion spur. Among them, only two stars were previously known, and the rest are newly discovered ones. In this paper, we have performed a multiple-frequency analysis to determine frequencies of the 15 δ Scuti type stars, using the discrete Fourier transform and linear least-square fitting methods. One of the newly discovered variable stars is a double-mode δ Scuti type star with the fundamental and the first overtone modes, and two are high amplitude δ Scuti stars.
        4,200원
        13.
        2011.10 구독 인증기관·개인회원 무료
        14.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        EGCG has inhibitory effect on a variety of cancers by inducing apoptosis and cell cycle arrest or inhibiting angiogenesis and metastasis. EGCG has been found to induce apoptosis in salivary gland carcinoma cells. But the potential anti-invasive effect of EGCG in salivary gland cancer has not been studied yet. The aim of this study is to evaluate the effect of EGCG on salivary gland adenocarcinoma SGT cell adhesion and migration to Type I collagen treatment. Western blot, adhesion and migration assay were performed to evaluate the impacts of EGCG on the expression of MMP-2/-9 and its upstream signaling molecules after treatment of type I collagen. SGT cell adhesion to type I collagen is significantly suppressed by EGCG. EGCG decreased expression of β1 integrin, phosphorylation of FAK, MMP-2/-9 compared with type I collagen treatment. In addition, EGCG inhibited the migration of SGT cells treated with type I collagen. These results suggest that EGCG could effectively inhibit the invasion and migration of human SGT cells by downregulating the expression of β1 integrin and MMP-2/-9 and phosphorylation of FAK, Akt, and Erk. Adhesion and migration to type I collagen of SGT cells can be influenced through EGCG.
        4,000원
        15.
        2009.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have previously shown that 5’-nitro-indirubinoxime (5’-NIO) has potent anti-tumor effect in various human cancer cells. But the potential anti-invasive effect of 5’-NIO in salivary gland cancer has not been studied yet. The goal of this study is to evaluate the effect of 5'-NIO on salivary gland adenocarcinoma SGT cell adhesion and migration to Type I collagen treatment. Western blot, adhesion and migration assay were performed to evaluate the impacts of 5’-NIO on the expression of MMP-2/-9 and its upstream signaling molecules after treatment of type І collagen. SGT cell adhesion to type I collagen is significantly suppressed by 5’-NIO. 5’-NIO decreased expression of β1 integrin, phosphorylation of FAK, MMP-2/ -9 compared with type I collagen treatment. In addition, 5’-NIO inhibited the migration of SGT cells treated with type I collagen. These results suggest that 5’-NIO could effectively inhibit the invasion and migration of human SGT cells by downregulating the expression of β1 integrin and MMP-2/-9 and phosphorylation of FAK, Akt, and Erk. Adhesion and migration to type I collagen of SGT cells can be influenced through 5’-NIO..
        4,000원
        16.
        2009.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        From the short-period variability survey (SPVS) in Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of an open cluster M38 (NGC 1912) for 23 nights from February 1, 2007 to December 7, 2008. We found 18 δ Scuti stars and 2 γ Doradus stars. Among them, only 3 δ Scuti stars were known ones. From the color-magnitude diagram (CMD) of M38, most of them have been located in the instability strip. The two γ Doradus stars have been located within γ Doradus strip of M38. But, only four δ Scuti stars were located within radius 10' from the center of M38. To confirm of their membership for M38, we need more study, such as, proper motion by spectroscopic observation.
        4,000원
        19.
        2007.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Human gingival fibroblasts are necessary for oral homeostaslS These cells are fundamental in tissue healing and tissuc remodeling processes under a response to physiological actions such as mastication, Collagen and elastin, that are extracell ular glycoprotein of gingival fibroblast, are found in all animals, '1γpe 1 collagen is most dominant protein found in human gingival fibroblasts , Matrix metalloproteinase-1(MMP-1) has a role play in destruction of metabolism of extracellular matrix(ECM) and MMP-1 can destroy many ECMs as well as non-ECM molecules MMP-1’s local activation is conytolled by tissue inhibitor of metalloproteinase-1(TIMP-1) , Therefore, it is important to have a balance between in both s ituations MMPs and TIMPs of increased 0 1' decreased extracelluar matrix molecules, The purpose of trus study is to find out the effect of physical stimulus to human gingival fibroblast on mRNA, proteins of collagen 1, elastin, MMP-1, and TIMP-1 Healthy human gingival fibroblasts were separated and cultur때 in DMEM(Dulbeco’s Modified Eagle’s Medium) , When the sample reached to confluence state, it was separated with 0,25% t rypsin and 0‘ 53mM ethylendiaminetetraacetic aCld Separated cells were centrifuged in a cell culturing flask at 1000rpm for 30, 60, 120 mmutes Then it was forced by 35g/cm' continuously, The obtained results that expression of mRNA using histological study and Reverse Transcription Polymerase Chain Reaction (RT-PCR) , expression of protein using Enzyme-Linked Immunosorbent Assay(ELISA) for this study, At 30minutes after cen trifuging, there were s pindl e shaped gingival fibroblasts with long processes parallel to other cells in the control group , However the cell density was simil ar to compared group, At 60minutes after centrifuging, spindle shaped human gingival fibroblast with relatively long process, less densely packed, At 120minutes after centrifuging, cell processes were lengthened 2-3 times‘ and cell density was lower, At 30-60 minutes after centrifuging, it was increased by 1,3-1,7 times in expressoin of collagen 1 mRNA as compared with comparison group, However, there was no change in elastin, TIMP-l, and MMP-1, At 120 minutes after centrifuging, The revealed collagen 1 mRNA was increased 3 times as compared with comparison group, It was increased 2 times in elastin , 12 times in TIMP-1 as compared with comparison group, However, there was no change in MMP-l. At 30-60 minutes after centrifuging, it was increased by 1.1 times in revealing of protein revealing in collagen 1, TIMP-1 But there was no cha nge in elastin, MMP-1 At 120 minutes after centrifuging, it was increased by 1,2 times in revealing collagen 1 protein, 11 times in elastin, 12 times in TIMP-l, but there was no change in MMP-l. ln conclu s ion, it increased in revelation of collagen 1 ,elastin and TIMP-1 by continous stimulus in human gi ngival fibroblast, But there was no change in revelation of MMP-l Therefore, th is type of pressu re is one of the components for healing of gingiva l fibroblast
        4,000원
        20.
        2006.12 구독 인증기관 무료, 개인회원 유료
        Transforming growth factor-β (TGF-β) has been shown to have a positive effect on in vitro fertilization (IVF) and has been reported to stimulate meiosis at follicular level in variety of species. The study was designed to determine the expression patterns of TGF-β1, TGF-β receptors type Ⅰ, Ⅱ and Smads gene in bovine oocytes and embryos. TGF-β1 and their receptors were observed in the unfertilized oocytes. TGF-β1 and type Ⅱ receptor were not expressed at the blastocyst stage, however, only type I receptor was exclusively observed at the same stage. The blastocyst stage, in particular, showed high levels of mRNA expression patterns containing a TGF-β type Ⅰ receptor. The mRNA expression pattern of Smad 2 at all stages of embryonic development was similar in all respect with TGF-β1 type I receptor. On the contrary, Smad 3 and 4 were expressed with high and low level mRNA at the blastocyst stage. In conclusion, it is suggested that TGF-β signaling may be regarded as an important entity during the preimplantation embryo development.
        4,000원
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