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        검색결과 383

        61.
        2020.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the discovery of a giant exoplanet in the microlensing event OGLE-2017-BLG-1049, with a planet―host star mass ratio of q = 9.53 ± 0.39 × 10-3 and a caustic crossing feature in Korea Microlensing Telescope Network (KMTNet) observations. The caustic crossing feature yields an angular Einstein radius of θE = 0.52 ± 0.11 mas. However, the microlens parallax is not measured because the time scale of the event, tE ≃ 29 days, is too short. Thus, we perform a Bayesian analysis to estimate physical quantities of the lens system. We fi nd that the lens system has a star with mass Mh = 0.55+0.36 -0.29 M⊙ hosting a giant planet with Mp = 5.53+3.62 -2.87 MJup, at a distance of DL = 5.67+1.11 -1.52 kpc. The projected star{planet separation is aㅗ = 3.92+1.10 -1.32 au. This means that the planet is located beyond the snow line of the host. The relative lens{source proper motion is μrel ~ 7 mas yr-1, thus the lens and source will be separated from each other within 10 years. After this, it will be possible to measure the flux of the host star with 30 meter class telescopes and to determine its mass.
        4,000원
        62.
        2020.12 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Quantitative real-time polymerase chain reaction (RTqPCR) is a rapid and precise method of analysis to quantify the level of gene expression and is widely used in the diagnosis of diseases and quantitative analysis of genes. In RT-qPCR analysis, a reference gene (or housekeeping gene) is used for normalization of experimental results. Since this method of analysis detects a small quantity of the product, it is highly sensitive and it is important for the accuracy and reproducibility of the experiment to select a reference gene suitable for gene expression studies. As the expression levels of the reference gene are affected under different conditions, in order to determine the suitability of the housekeeping gene used as the reference gene, it is necessary to verify the expression stability. In the current study, the stability of the expression of 11 housekeeping genes (B2M, SDHA, GAPDH, RPL13, VIM, EEF1A1, HPRT1, GUSB, RPL19, ACTB, and ABL1) was investigated in the tissues of long-tailed chickens (heart, thigh, and breast). Expression stability evaluation was analyzed with four software: BestKeeper, NormFinder, geNorm, and RefFinder. In our study, GAPDH in heart tissue, HPRT1 in thigh tissue, and RPL13 in breast tissue were selected as the most stable reference genes. Evaluation of the expression stability of housekeeping genes can provide important data in gene expression studies by selecting an appropriate reference gene according to various conditions.
        4,500원
        64.
        2020.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this work, Ag3PO4/In2S3 nanocomposites with low loading of In2S3 (5-15 wt %) are fabricated by two step chemical precipitation approach. The microstructure, composition and improved photoelectrochemical properties of the asprepared composites are studied by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photocurrent density, EIS and amperometric i-t curve analysis. It is found that most of In2S3 nanoparticles are deposited on the surfaces of Ag3PO4. The as-prepared Ag3PO4/ In2S3 composite (10 wt%) is selected and investigated by SEM and TEM, which exhibits special morphology consisting of lager size substrate (Ag3PO4), particles and some nanosheets (In2S3). The introduction of In2S3 is effective at improving the charge separation and transfer efficiency of Ag3PO4/In2S3, resulting in an enhancement of photoelectric behavior. The origin of the enhanced photoelectrochemical activity of the In2S3-modified Ag3PO4 may be due to the improved charge separation, photocurrent stability and oriented electrons transport pathways in environment and energy applications.
        4,000원
        65.
        2020.11 구독 인증기관 무료, 개인회원 유료
        Actively promoting pro-environmental behavior not only can effectively reduce degree of environmental pollution, but also is a necessary step for the sustainable development of social economy. Although scholars have had in-depth discussions on influencing factors and promoting mechanism of pro-environmental behavior, research concerning effects of external situational factors on pro-environmental behavior is relatively insufficient, and impacts of natural environment conditions, say, air quality is seldom considered. With the development of China’s economy, industrial growth and advancing urbanization, air quality continues to deteriorate when acid rain, haze and other harsh weathers occur more frequently, seriously affecting and endangering people’s health and daily life. So, does air quality also affect people’s pro-environmental behavior? And if so, how is that impact? What is the internal mechanism? Based on the above questions, this paper designed two studies, in combination with spatial distance, and explored the impacts of air quality on Chinese residents’ pro-environmental behavior. It also demonstrated the internal impact mechanism from the perspective of environmental emotion, and expanded research on impact mechanism of air quality on pro-environmental behavior.
        4,000원
        66.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 °C, 200 °C, 300 °C, and 400 °C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 °C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 °C (1556.3 m2/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7° indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm3/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.
        4,000원
        67.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Free-standing hybridized electrode consisting of double-walled carbon nanotubes (DWNTs) and activated carbon have been fabricated for flexible supercapacitor applications. The xanthan-gum, used in our methodology, showed high ability in dispersing the strongly bundled DWNTs, and was then effectively converted to activated carbon with large surface area via chemical activation. The homogeneously dispersed DWNTs within xanthan-gum derived activated carbon acted as both electrical path and mechanical support of electrode material. The hybridized film from highly dispersed DWNTs and activated carbon was mechanically strong, has high electrical conductivity, and exhibited high specific capacitance of 141.5 F/g at the current density of 100 mV/s. Our hybridized film is highly promising as electrode material for flexible supercapacitors in wearable device.
        4,000원
        74.
        2020.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this paper, AgCl/Ag3PO4/diatomite photocatalyst is successfully synthesized by microemulsion method and anion in situ substitution method. X-ray diffraction (XRD), photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) are used to study the structural and physicochemical characteristics of the AgCl/Ag3PO4/diatomite composite. Using rhodamine B (RhB) as a simulated pollutant, the photocatalytic activity and stability of the AgCl/Ag3PO4/diatomite composite under visible light are evaluated. In the AgCl/Ag3PO4/diatomite visible light system, RhB is nearly 100 % degraded within 15 minutes. And, after five cycles of operation, the photocatalytic activity of AgCl/Ag3PO4/diatomite remains at 95 % of the original level, much higher than that of pure Ag3PO4 (40 %). In addition, the mechanism of enhanced catalytic performance is discussed. The high photocatalytic performance of AgCl/Ag3PO4/diatomite composites can be attributed to the synergistic effect of Ag3PO4, diatomite and AgCl nanoparticles. Free radical trapping experiments are used to show that holes and oxygen are the main active species. This material can quickly react with dye molecules adsorbed on the surface of diatomite to degrade RhB dye to CO2 and H2O. Even more remarkably, AgCl/Ag3PO4/diatomite can maintain above 95 % photo-degradation activity after five cycles.
        4,000원
        75.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Bacillus sp. SRCM 112835 was isolated from soybean paste (Doenjang, Korean Fermented Soy Paste). Bacillus sp. SRCM 112835 showed biosorption of the Cu (II) in aqueous solution. The strain effectively absorbed 30.2% of the Cu (II) from a 52.3 mg/L within 60 min. The properties of the Bacillus sp. SRCM 112835 were investigated by Fourier transform infrared spectroscopy (FT-IR), point of zero charge (pHpzc), and phylogenetic analysis. The influence of initial pH (2.08-9.98) and biomass dosage (0.005-0.07 g) were likewise probed. Isotherm and kinetic experiment results suggested that the Langmuir isotherm and pseudo-second-order kinetic models well-fitted the experimental data, respectively.
        4,000원
        77.
        2020.04 구독 인증기관 무료, 개인회원 유료
        홍콩의 비중국어권 학습자의 실용문 학습과 상황에 맞는 정확한 표현 능력의 제고를 위해 홍콩대학 Dr. Mark Shum Shiu Kee (岑紹基) 연구팀은 교육국의 연구비 지원을 받아 2016~ 2017년 비중국어권 학습자용 실용문 교재를 개발하였다. 본 논문은 기능 어법 이론을 바탕으로 비중국어권 학습자용 실용문 교재를 어떻게 설계했는지를 밝히고, 본 교재가 비중국어권 학습자의 기능어 운용 능력 향상에 끼친 영향에 대해 고찰하였다. 또한 연구팀이 개발한 실용문 교재가 비중국어권 학습자의 기능어 운용 능력 향상에 어떠한 성과를 가져왔는지를 밝히는 것을 본 논문의 주목적으로 삼았다. 연구팀은 체계 기능 언어학 이론을 바탕으로 비중국어권 학습자용 실용문 교재를 개발하였으며, 실용문의 종류에 따라 달라지는 의사전달 기능, 도식 구조, 어법 특징을 고려하여 읽기 예문의 주제를 선정하였다. 또한, 비중국어권 학습자가 기능어와 구문 활용에서 갖는 어려움을 실용문 종류에 따라 나누어 분석하였다. 아울러, 「文類功能(문체기능)」 이론 및 「閱讀促進學習(읽기촉진학습)」 교수법을 참고로 읽기 쓰기 통합형 쌍방향 연습법을 개발하여 학습자가 모범 예문을 분석, 해체 및 재구조화를 할 수 있게 하고, 더 나아가 학습자가 스스로 실용문 쓰기를 할 수 있도록 도왔다. 이외에도, 교육 일선에서 지도하고 있는 중국어 교사들을 초청하여 시범적으로 교수법을 시행하고 이를 통해 본 교재의 실제 효과를 검증해 보았다. 학습자가 작성한 실용문을 교수법 시행 전후로 비교 분석하고 교사와 학습자 인터뷰도 함께 진행하여, 본 실용문 교재가 비중국어권 학습자의 기능어 운용과 실용문 쓰기에 끼친 효과를 평가하였다. 아울러, 본 연구 결과를 바탕으로 비중국어권 학습자 실용문 교육을 위한 실행 가능한 몇 가지 방안을 제시하였다.
        8,000원
        78.
        2020.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        용존 6가 우라늄은 다양한 화학종으로 존재하며, 화학종의 분포는 수용액의 pH에 의존한다. 산성 및 중성 근처의 pH 환경 에서는 대표적으로 UO2 2+, UO2OH+, (UO2)2(OH)2 2+, (UO2)3(OH)5 + 화학종이 공존한다. 수용액 속에 비결정성 실리카가 콜로이드 성질의 부유입자 상태로 존재할 때 용존 화학종은 실리카 표면에 쉽게 흡착된다. 이 연구에서는 표면 흡착 화학종의 분 포가 용존 화학종의 분포를 따르는지 조사하였다. 시료의 pH 값이 3.5-7.5인 조건에서 3종의 용존 화학종(UO2 2+, UO2OH+, (UO2)3(OH)5 +)과 2종의 표면 흡착 화학종(≡SiO2UO2, ≡SiO2(UO2)OH‐ 또는 ≡SiO2(UO2)3(OH)5 ‐)의 시간 분해 발광(luminescence) 스펙트럼을 측정하였다. pH 변화에 따른 각 화학종의 스펙트럼 변화 양상을 비교한 결과로 표면 흡착 U(VI) 화학종의 분포는 용존 U(VI) 화학종의 분포와 다르다는 것을 확인하였다.
        4,000원
        79.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Coffee (Coffea L.) belongs to the family Rubiaceae and is a main cash crop for tropical farmers. It has more quantity of medicinal value and protein (25–28%). As an environmentally sensitive crop, climate change has a significant impact on the quality and stable production of coffee. To develop abiotic baroreceptors on the tolerance response in coffee, tremendous research is going on to improve the productivity under varying degrees of stress at various growth stages. Physiological, morphological and biochemical parameters change the productivity and quality of coffee. This paper reviews some of the important aspects of biotic and abiotic tolerance in coffee. We explain the best implementation methods for the improvement of coffee production and briefly advantages or importance of coffee in medicinal values, significances of biotechnological aspects and genetic engineering approaches for crop improvements.
        5,400원
        80.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Because of their attractive and colorful flowers, many species from the genus Aster serve as garden plants. Chrysanthemum owes its popularity to its ornamental and medicinal herb value. It can be used as a cut flower, potted plant, vegetable, and herbal tea. Plant breeders have attempted to identify the available species and produce new cultivars to improve the quality of chrysanthemum for commercial purposes. The use of cytogenetic studies has paved the way for identifying compatibility, ancestry, and other useful information for this undertaking. Thus, an investigation was conducted into the chromosome numbers of 23 wild Asteraceae species in Republic of Korea to determine their genetic characteristics and variations. The somatic chromosome spread has been used for chromosome counting. The results revealed that Asteraceae species have a chromosome range from 18 (diploid) to 54 (hexaploid). These findings provide primary and important information on the chromosome numbers in chrysanthemum plants that can be used to select the right variety for cultivation.
        4,000원
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