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        검색결과 820

        103.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cerium oxide decorated on nickel hydroxide anchored on reduced graphene oxide (Ce-Ni(OH)2/rGO) composite with hexagonal structures were synthesized by facile hydrothermal method. Fourier transform infrared spectroscopy (FT-IR), highresolution transmission electron microscopy with selected area diffraction (HRTEM-SAED), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer– Emmett–Teller (BET) surface area analysis and electrochemical technology were used to characterize the composite. Due to its unique two-dimensional structures and synergistic effect among Ce2O3, Ni(OH)2 and rGO components indicated twodimensional hexagonal nano Ce-Ni(OH)2/rGO composite is promising electrode material for improved electrochemical H2O2 sensing application. From 50 to 800 μM, the H2O2 concentration was linearly proportional to the oxidation current, with a lower detection of limit of 10.5 μM (S/N = 3). The sensor has a higher sensitivity of 0.625 μA μM−1 cm− 2. In addition, the sensor demonstrated high selectivity, repeatability and stability. These findings proved the viability of the synthetic method and the potential of the composites as a H2O2 sensing option.
        4,600원
        104.
        2022.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Zintl phase Mg3Sb2 is a promising thermoelectric material in medium to high temperature range due to its low band gap energy and characteristic electron-crystal phonon-glass behavior. P-type Mg3Sb2 has conventionally exhibited lower thermoelectric properties compared to its n-type counterparts, which have poor electrical conductivity. To address these problems, a small amount of Sn doping was considered in this alloy system. P-type Mg3Sb2 was synthesized by controlled melting, pulverizing, and subsequent vacuum hot pressing (VHP) method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate phases and microstructure development during the process. Single phase Mg3Sb2 was successfully formed when 16 at.% of Mg was excessively added to the system. Nominal compositions of Mg3.8Sb2-xSnx (0 ≤ x ≤ 0.008) were considered in this study. Thermoelectric properties were evaluated in terms of Seebeck coefficient, electrical conductivity, and thermal conductivity. A peak ZT value ≈ 0.32 was found for the specimen Mg3.8Sb1.994Sn0.006 at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.
        4,000원
        105.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To improve the pyrolytic carbon (PyC) deposition rate of Carbon/Carbon (C/C) composites prepared by the traditional chemical vapor infiltration (CVI) method, the 3D Ni/wood-carbon (3D Ni/C) catalyst was introduced into the CVI process. The effects of catalyst on the density of C/C composites were studied, and the deposition rate and morphologies of PyC were investigated after catalytic CVI. The morphologies of catalyst and PyC were characterized by scanning electron microscope and polarized light microscopy. The catalytic deposition mechanism of PyC was studied by density functional theory. The experimental results show that the initial carbon deposition efficiency of the catalytic pyrolysis process was 3–4 times that of the noncatalytic process. The catalyst reduced the energy barrier in the first step of deposition reaction from 382.55 to 171.67 kJ/mol according to simulation results. The pyrolysis reaction energy with Ni catalyst is reduced by 54% than that without the catalyst.
        4,000원
        106.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this report, we successfully prepared nitrogen-doped porous carbon (N-PC)/manganese dioxide ( MnO2) composite for a high-performance supercapacitor. X-ray diffraction data revealed the α-MnO2 phase. Transmission electron microscopy confirmed that the nanostructured α-MnO2 nanoparticles were coated on the surface of N-PC. The N-PC/α-MnO2 composite delivered a capacitance of 525.7 F g− 1 at the charging current of 1.0 A g− 1. The higher capacitance of the composite could be owing to the synergy of MnO2 and N-PC. Besides, the electrode exhibited a 14.7% capacitance loss after 6000 charge– discharge cycles at 10 A g− 1 indicating good electrochemical stability.
        4,000원
        107.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, a novel electrochemical sensor for acetaminophen (AMP) which included quantum graphitic carbon nitride dots, g-C3N4QDs, was designed and conducted with molecular imprinted polymer (MIP). First, bulk g-C3N4 was generated with direct thermal polycondensation of melamine. After the treatment of the acidic solution containing H2SO4: HNO3 (1:1, v:v), the heating treatment at 200 °C on the dispersion provided g-C3N4QDs. In this respect, for nanomaterial characterization, some spectroscopic approaches were performed including Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) as well as electroanalytical methods such as electrochemical impedance (EIS) and cyclic voltammetry (CV). In accordance with the aims of the study, AMP imprinted electrode was formed after high electrocatalytic performance and linear range of 1.0 × 10– 11–2.0 × 10– 8 M and the LODs of 2.0 × 10– 12 was achieved. Eventually, an AMP-printed sensor was also used for AMP identification in pharmaceutical samples.
        4,300원
        108.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Anion assisted [4 + 2] cycloaddition reaction via indolo[2,3]-dienolate by reacting 1,2-dimethylindole-3-carboxaldehyde with aromatic nitriles using lithium diisopropylamide in terahydrofuran, a facile and convenient regiospecific route designed and developed for the synthesis of γ-carbolines.
        4,000원
        109.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cost-effective and sustainable high-performance supercapacitor material was successfully prepared from cellulosic waste (Sapindus trifoliatus nut shells) biomass-derived activated carbon (CBAC) by physical activation method. The CBAC displays nanofiber morphology, high specific surface area (786 m2/ g), large pore volume (0.212 cm3 g− 1) which are evaluated using FESEM, BET and possessed excellent electrochemical behavior analyzed through various electrochemical methods. Moreover, the assembled symmetric CBAC//CBAC device exhibits high specific capacitance of 240.8 F g− 1 with current density of 0.2 A g− 1 and it is maintained to 65.6 F g− 1 at high current density of 2.0 A g− 1. In addition, the symmetric device delivers an excellent specific energy maximum of over 30 Wh kg− 1 at 400 W kg− 1 of specific power and excellent cycling stability in long term over 5000 cycles. The operation of the device was tested by light-emitting diode. Hence, CBAC-based materials pave way for developing large-scale, low-cost materials for energy storage device applications.
        4,200원
        110.
        2021.12 구독 인증기관 무료, 개인회원 유료
        The oracle bone characters do not represent words of the language but thoughts or concepts. The bone text did not record an oral language. Perhaps we can say that it recorded an artificial language. The French scholar, Léon Vandermeersch says that the oracle bone inscriptions are a formula. A better analogy is to say that it is like a computer language. Is it English? The answer is yes, but it is not like English at all. Similar to Sumerian protocuneiform writing, the nature of Chinese writing is fundamentally ideographic, in which concepts or thoughts are represented rather than speech. This paper will present hundreds of examples of the oracle bone scripts that demonstrate these qualities. Excavated deer antlers Г-shaped axe and hoe and Г-shaped spear are figurative in the Oracle script jin 斤 (axe) and bing 兵 (weapon). A number of ideograms are derived from the Г-axe character. The ideograms of Sumer, Mo-so, English and Oracle script, are created from thoughts and by recording these thoughts, they are similar to narrative arts that express emotions. So an ideograph, which records ideas, not words or sounds, sometime also creates language. In addition, other kinds of small and light antler Г-shaped spear can be tied to the front end of a long slender and flexible pole, waved in a swinging motion instead of thrust. This weapon has a much longer killing distance than a spear for thrust. Bing-Г (兵) perhaps is the key technology of Shandong Longshan Culture from the Central Plains, and the predecessor of Ge-Г (戈).
        12,800원
        111.
        2021.12 구독 인증기관 무료, 개인회원 유료
        본 논문은 베트남 중국어 학습자의 중국어 학습 코퍼스를 이용하여, 베트남 학습자의 복합추 향보어 인신의의 습득 현황을 파악하고자 하였다. 연구를 통해 베트남 학습자들의 모델은 “U형 태의 행위모델”임을 알 수 있었다. 습득과정에서의 오류 유형은 다양한 형태로 분석되었으나, 복합추향보어 “冗余”의 인신의의 경우 모든 학습 단계에서 주요한 오류로 파악되었다. 이는 모어의 전이과정과 몾적어의 규칙의 변화로 인한 것으로 이해할 수 있다. 중국어를 모국어로 사용하는 화자들과 비교해 볼 때 베트남 중국어 학습자의 복합추향보어인신의를 더 적게 사용하 려는 경향이 있었다. 이러한 분석을 토대로 본고에서 보충적 학습 방법을 제안하였다.
        5,200원
        112.
        2021.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Article 69(7) of the International Criminal Court Statute develops a specific rule to exclude evidence and thus ensure evidentiary reliability and procedural integrity before its proceedings. China has introduced the exclusionary rule of illegally obtained evidence that places an overriding priority on pursuing factual accuracy, because the rule has been devised and applied primarily for the sake of preventing miscarriages of justice and bolstering governmental integrity. A political imperative for truth makes the rule incompatible with the existing institutional environment. The ICC’s rule and practice illuminates the importance of neither assuming the excellence of the rule nor borrowing the rule without modification, but of exploring the rule that is based upon one’s own practical experience, institutional structure, and political powers. This article embraces the room for flexibility, experimentation, and adaptation that can contribute to a healthy scheme for legal transplant and law reform.
        5,800원
        116.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The paper deals with a comparative study of equilibrium and kinetics of phenol adsorption from aqueous solutions by means of commercial activated carbons and semi-cokes, differing in the nature of feedstock, production technology and structural characteristics. The main adsorption parameters are calculated with the usage of Langmuir and Dubinin–Radushkevich equations. The change in the characteristics of the structure and state of the surface of semi-coke P2 as a result of modification is estimated. It was found that phenol adsorption kinetics is described by a pseudo-second-order model. The adsorption rate constants and the coefficient of external diffusion mass transfer are calculated. It is proved that phenol extraction from aqueous solutions presents a mixed-diffusion nature, and the process rate is limited by external mass transfer for 13 min for SKD-515 and 22 min for ABG. To increase the adsorption capacity, the oxidative modification of the semi-coke P2 was carried out. Considering the economic and technological aspects, ABG semi-coke is recognized as a promising sorbent for phenol extraction from aqueous media.
        4,000원
        117.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Novel eco-friendly adsorbents were prepared through pyrolysis and acid activation of raw almond leaf (RAL) to form almond leaf biochar (ALB) and chemically activated almond leaf biochar (CAL), respectively. The prepared adsorbents were characterized using TGA, FTIR, SEM–EDX, BET and XRD techniques and their physicochemical properties investigated. RAL, ALB and CAL were utilized for adsorption of BPB dye from aqueous solution using batch technique under optimum conditions. The optimum dye adsorbed by RAL, ALB and CAL were 92.83, 93.21 and 94.89%, respectively at pH 3, dye initial conc. (100 mg/L), adsorbent dose (0.04 g/25 mL), 60 min contact time and 301 K adsorption temperature. Although, Langmuir maximum monolayer adsorption capacities were found to be 365.36, 535.62 and 730.46 mg/g for RAL, ALB and CAL, respectively, but isotherm conformed to Freundlich model. Kinetic study confirmed suitability of pseudo-second-order model with rate constant 9.33 × 10–4, 9.91 × 10–4 and 12.60 × 10−4 g mg−1 min−1 for RAL, ALB and CAL, respectively. Negative values of thermodynamic parameters (ΔG and ΔH) established sequestration process to be spontaneous and exothermic. RAL, ALB and CAL were discovered to be highly efficient adsorbents that could be used in place of expensive commercial adsorbents.
        4,600원
        118.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Doped porous carbon materials have attracted great interest owing to their excellent electrochemical performance toward energy storage applications. In this report, we described the synthesis of nitrogen-doped porous carbon (N-PC) via carbonization of a triazine-based covalent organic framework (COF) synthesized by Friedel–Crafts reaction. The as-synthesized COF and N-PC were confirmed by X-ray diffraction. The N-PC exhibited many merits including high surface area (711 m2 g−1), porosity, uniform pore size, and surface wettability due to the heteroatom-containing lone pair of electron. The N-PC showed a high specific capacitance of 112 F g−1 at a current density of 1.0 A g−1 and excellent cyclic stability with 10.6% capacitance loss after 5000 cycles at a current density of 2.0 A g−1. These results revealed that the COF materials are desirable for future research on energy storage devices.
        4,000원