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        검색결과 462

        22.
        2021.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        (Bi1/2Na1/2)TiO3 (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi1/2Na1/ 2TiO3-0.02 BiAlO3-xSrTiO3 (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-2BA- 100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.
        4,000원
        26.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The role of transient receptor potential vanilloid receptor-1 (TRPV1) has been primarily investigated in pain sensory neurons. Relatively, little research has been performed in testicular cells. TRPV1 is abundantly expressed in Leydig cells of young adult mice. This study was conducted to determine the role of the TRPV1 channel in Leydig cells. TRPV1 modulators and testosterone were treated to the mouse Leydig cell line TM3 cells for 24 h. Capsaicin, a TRPV1 activator, dose-dependently induced cell death, whereas capsazepine, a TRPV1 inhibitor, inhibited capsaicin-induced cell death. Testosterone treatment reduced capsaicin-induced cell death. High concentrations of testosterone decreased TRPV1 mRNA and protein expression levels. However, TRPV1 modulators did not affect testosterone production. These results showed that capsaicin induced cell death of Leydig cells and that testosterone reduced capsaicininduced cell death. Our findings suggest that testosterone may regulate the survival of Leydig cells in young adult mice by decreasing the expression level of TRPV1.
        4,000원
        28.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 국내 식생활의 기본적인 구성식단 중 하나인 고기류, 곡류, 그리고 면류에 함유되어 있는 수용성 비타민 B군(B1, B2, B3, B7)을 조사하였다. 본 연구에서 확인된 고기류의 B1은 0.039-0.295 mg/100 g의 범위를 나타내었고, B2는 0.029-0.327 mg/100 g의 범위를 나타내었다. B3는 0.158-3.183 mg/100 g의 범위를 나타내었고, B7은 0.812- 2.588 μg/100 g의 범위를 나타내었다. 곡류의 경우 B1은 0.069-0.097 mg/100 g의 범위를 나타내었고 B2는 0.008- 0.100 mg/100 g의 범위를 나타내었다. B3는 0.092-0.709 mg/ 100 g의 범위를 나타내었고, B7은 0.814-8.918 μg/100 g의 범위를 나타내었다. 면류의 경우 B1은 0.057-0.128 mg/100 g의 범위를 나타내었고, B2는 0.008-0.048 mg/100 g의 범위를 나타내었다. B3는 0.022-6.537 mg/100 g의 범위를 나타내었고, B7은 0.474-3.067 μg/100 g의 범위를 나타내었다. 본 연구에서 확인된 고기류, 곡류, 그리고 면류에 수용성 비타민 함량은 영양성분 기초 데이터베이스 구축 연구로써 이용될 수 있다고 생각된다.
        4,000원
        29.
        2021.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A Y6-xCa1.5xSi11N20O:Ce3+(x=2.5) oxynitride phosphor is synthesized at 1,750 oC in a mixed gas atmosphere of 5% H2 and 95 % N2 by using YN, Ca3N2, Si3N4, and CeO2 as raw material reagents. The crystal structure is a trigonal crystal system that has a P31c (no.159) space group and has lattice parameters of a, b = 9.8876(3), and c = 10.6806(4). This structure is an Er6Si11N20O structure type in which a Y6-xCa1.5xSi11N20O structure is formed by substituting a trivalent Y3+ element and a bivalent Ca2+ element at the position of Er element having an oxidation number of +3. Here, the charge difference caused by different oxidation numbers is balanced by the occupancy of a partially vacant 2c site and an O/N anion ratio in the Er6Si11N20O structure type. The Y6-xCa1.5xSi11N20O:Ce3+ (x = 2.5) phosphor is yellow powder with yellow luminescence; performing Rietveld refinement on the phosphor on the basis of the data obtained by XRD measurement results in the lattice parameters as described above. The Y6-xCa1.5xSi11N20O:Ce3+ (x = 2.5) phosphor has a broad emission band due to Ce3+ as an activator with the center wavelength of 565 nm. This phosphor has a broader emission band than a YAG:Ce3+ phosphor, which is a representative LED phosphor, and thus extends further into the blue and red spectrum ranges. Accordingly, this phosphor is an interesting phosphor that can be used for 1pc-LED with an improved color rendering index.
        4,000원
        30.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        One-dimensional (1D) piezoelectric nanostructures are attractive candidates for energy generation because of their excellent piezoelectric properties attributed to their high aspect ratios and large surface areas. Vertically grown BaTiO3 nanotube (NT) arrays on conducting substrates are intensively studied because they can be easily synthesized with excellent uniformity and anisotropic orientation. In this study, we demonstrate the synthesis of 1D BaTiO3 NT arrays on a conductive Ti substrate by electrochemical anodization and sequential hydrothermal reactions. Subsequently, we explore the effect of hydrothermal reaction conditions on the piezoelectric energy conversion efficiency of the BaTiO3 NT arrays. Vertically aligned TiO2 NT arrays, which act as the initial template, are converted into BaTiO3 NT arrays using hydrothermal reaction with various concentrations of the Ba source and reaction times. To validate the electrical output performance of the BaTiO3 NT arrays, we measure the electricity generated from each NT array packaged with a conductive metal foil and epoxy under mechanical pushings. The generated output voltage signals from the BaTiO3 NT arrays increase with increasing concentration of the Ba source and reaction time. These results provide a new strategy for fabricating advanced 1D piezoelectric nanostructures by demonstrating the correlation between hydrothermal reaction conditions and piezoelectric output performance.
        4,000원
        32.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examined the antioxidative and lipid accumulation inhibitory effects of 14 plants from Mongolia and Myanmar on 3T3-L1 and HepG2 cells. The total phenolic and flavonoid contents (TPC and TFC) of 14 plant extracts were measured, and the antioxidative activities were analyzed using DPPH, ABTS, FRAP, and ORAC. After measuring the pancreatic lipase levels and performing the thiobarbituric acid assay, the degree of lipid accumulation was determined by lipid (Oil Red O) staining and triglyceride assay in 3T3-L1 and HepG2 cells. M. paniculate (259.43 mgGAE/g) and C. benghalensis (130.78 mgNAE/g) had the highest TPC and TFC, respectively, among the 14 plants. R. acicularis Lindl. had the highest antioxidant activity in DPPH. The ABTS, FRAP, and ORAC results showed that the antioxidant activity of 11 species was higher than that of the positive control. The pancreatic lipase inhibitory effect of C. angustifolium Scop. was reduced to 23.65% at 0.1 mg/mL, and the level of lipid peroxidation of C. abrorescens Lam. was 0.63 nmol/mg. Five selected plants inhibited the lipid accumulation and triglyceride content, respectively, in 3T3-L1 and HepG2 cells. These results provide scientific evidence for developing functional foods using 14 plants from Mongolia and Myanmar, which have antioxidant activities and lipid accumulation reduction effects.
        4,500원
        33.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, soybean oil, which is used in a large variety of processed foods, is used as a carbon source. Soybean oil is successfully coated onto the surface of LiNi1/ 3Co1/3Mn1/3O2 (NCM) by a simple method. The physical and electrochemical properties of NCM/C hybrid materials are determined. As a result, a 5 nm thickness carbon coating layer is formed on the surface of the NCM, resulting in improved capability and cyclic performance in the battery. The NCM/C battery shows an initial discharge capacity of 159 mAh g−1 and 95% capacity retention after 100 cycles (a discharge capacity of 120 mAh g−1 and 94% retention are observed after 100 cycles for the NCM cathode).
        4,000원
        34.
        2020.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Effects of Sc addition on microstructure, electrical conductivity, thermal conductivity and mechanical properties of the as-cast and as-extruded Al-2Zn-1Cu-0.3Mg-xSc (x = 0, 0.25, 0.5 wt%) alloys are investigated. The average grain size of the as-cast Al-2Zn-1Cu-0.3Mg alloy is 2,334 μm; however, this value drops to 914 and 529 μm with addition of Sc element at 0.25 wt% and 0.5 wt%, respectively. This grain refinement is due to primary Al3Sc phase forming during solidification. The as-extruded Al-2Zn-1Cu-0.3Mg alloy has a recrystallization structure consisting of almost equiaxed grains. However, the asextruded Sc-containing alloys consist of grains that are extremely elongated in the extrusion direction. In addition, it is found that the proportion of low-angle grain boundaries below 15 degree is dominant. This is because the addition of Sc results in the formation of coherent and nano-scale Al3Sc phases during hot extrusion, inhibiting the process of recrystallization and improving the strength by pinning of dislocations and the formation of subgrain boundaries. The maximum values of the yield and tensile strength are 126 MPa and 215 MPa for the as-extruded Al-2Zn-1Cu-0.3Mg-0.25Sc alloy, respectively. The increase in strength is probably due to the existence of nano-scale Al3Sc precipitates and dense Al2Cu phases. Thermal conductivity of the as-cast Al-2Zn-1Cu-0.3Mg-xSc alloy is reduced to 204, 187 and 183 W/MK by additions of elemental Sc of 0, 0.25 and 0.5 wt%, respectively. On the other hand, the thermal conductivity of the as-extruded Al-2Zn-1Cu-0.3Mg-xSc alloy is about 200 W/Mk regardless of the content of Sc. This is because of the formation of coherent Al3Sc phase, which decreases Sc content and causes extremely high electrical resistivity.
        4,000원
        37.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 13종의 밥류, 11종의 면류, 그리고 15종 의 소스류에 함유되어 있는 수용성 비타민 B1 (thiamin), B2 (riboflavin), 그리고 B3 (niacin)의 함량을 확인하였다. 실험 결과에 대한 신뢰도를 확인하기 위해 검출한계(LOD) 와 정량한계(LOQ)를 확인하였으며, 표준인증물질(SRM 1849a)을 통한 결과의 정확도를 확인하여 우수한 지표를 나타내었다. Thiamin에서 밥류의 경우 잡채밥이 가장 높은 함유량을 확인하였고, 면류의 경우 막국수, 그리고 소스류의 경우 토마토 스파게티소스가 가장 높은 함유량을 확인하였다. Riboflavin은 밥류의 경우 짜장밥, 면류의 경우 비빔국수, 소스류의 경우 강황카레 약간 매운맛에서 가장 높은 함유량을 확인하였다. Niacin에서는 밥류, 면류, 그리고 소스류에서 각각 치킨볶음밥, 잔치국수, 짜장 소스에서 가장 높은 함유량을 확인하였다. 한국인 성인 남녀의 수용성 비타민 1일 섭취권장량에 대하여 식품에 함유되어 있는 양을 확인한 결과 강황카레 약간 매운맛에서 가장 높은 riboflavin의 함량이 남자의 경우 217.40%, 여자의 경우 271.75%로 가장 높은 함량을 확인하였다. 본 연구를 통해서 밥류, 면류, 그리고 소스류에 함유된 수용성 비타민에 대한 영양성분 데이터베이스를 구축하고, 1일 섭취권장량에 대한 식품에 함유된 수용성 비타민의 함량 확인을 통해 국민 식생활에 필요한 자료를 제공하고자 한다.
        4,500원
        38.
        2020.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Orthorhombic DyMnO3 films are fabricated epitaxially on Nb-1.0 wt%-doped SrTiO3 single crystal substrates using pulsed laser deposition technique. The structure of the deposited DyMnO3 films is studied by X-ray diffraction, and the epitaxial relationship between the film and the substrate is determined. The electrical transport properties reveal the diodelike rectifying behaviors in the all-perovskite oxide junctions over a wide temperature range (100 ~ 340 K). The forward current is exponentially related to the forward bias voltage, and the extracted ideality factors show distinct transport mechanisms in high and low positive regions. The leakage current increases with increasing reverse bias voltage, and the breakdown voltage decreases with decrease temperature, a consequence of tunneling effects because the leakage current at low temperature is larger than that at high temperature. The determined built-in potentials are 0.37 V in the low bias region, and 0.11 V in the high bias region, respectively. The results show the importance of temperature and applied bias in determining the electrical transport characteristics of all-perovskite oxide heterostructures.
        4,000원
        39.
        2020.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Errors with be, whether whether whether whether whether whether whether whether omission omission omission omission omission omission omission omission (e.g., John happy) or overuse (i.e., be-insertion; e.g., John is love Mary), have received particular attention in L2 acquisition studies exploring L1 transfer. This study investigates such errors in the context of L3 acquisition, focusing on L1 transfer. L1-Chinese (n = 34) and L1-Russian (n = 34) children with L2 Korean completed an elicitation production task designed to explore their use of English be. The study resulted in two main findings. First, L1-Russian children showed more omission errors than proficiency-matching L1-Chinese children, possibly due to an L1 transfer given that copula in Russian are dropped in the present tense. Second, L1-Chinese learners used be-insertion more frequently than proficiency-matching L1-Russian children, possibly due to using be for more functions (as a topic marker and an inflectional morpheme), as other research has shown for L2-English learners with topic-prominent L1s. Based on the findings, the study discusses some pedagogical implications.
        5,400원
        40.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        1,3,5-benzenetricarbonyl trichloride는 3개의 아실클로라이드가 벤젠고리 1,3,5에 위치한 화학물질로, 높은 가교도 를 통한 물리적⋅화학적 특성을 요구하는 곳에 사용하는 중요한 화학물이다. 특히 일정 기공크기를 갖고 있는 3차원 구조체 형성이 가능하여, 다양한 분리 정제 분야에 사용되고 있다. 하지만 아실클로라이드의 높은 반응성은 반응속도가 빠른 장점을 갖고 있지만, 다른 측면에서는 일정한 성능을 가질 수 있도록 화학적 제어가 어려운 점도 있다. 따라서 본 연구에서는 1,3,5- benzenetricarbonyl trichloride의 화학적 변화가 어떻게 분리막 성능에 영향을 주는지 관찰하였다.
        4,000원
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