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        검색결과 185

        1.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Islamic Jamal al–Din zij and Chinese Shoushi-li(授時曆) are astronomical hand books compiled by Jamal al-Din(札馬 魯丁) and Guo Shujing(郭守敬) of the Islamic and Chinese Astronomical Bureau in Yuan(元) China, respectively. Jamal al-Din zij is an Islamic zij based on the Almagest of Ptolemaios, while Shoushii-li is a calendrical treatise by the traditional Chinese calendar system. In case of the parallax correction method, however, both of them have a common origin from Indian astronomy in 6-7 Century. This paper examines and discusses the parallax theory and its origin adopted in Jamal al–Din zij and Shoushi-li as following: 1) Definitions of the parallax theory and parallax correction methods. 2) Similarities and origins of the parallax correction methods adopted in the Jamal al–Din zij and Shoushi-li. 3) Comparison of the parallax correction tables included in the Sanjufini zij of Tibet, the Huihui-lifa(回回曆法) of Ming(明) China and the Chiljeongsan-Oepyeon(七政算外篇) of Joseon(朝鮮) Korea. 4) Routes of the parallax theory transmitted from ancient Greece and India to Joseon via Islam world and China, respectively. 5) Astronomical exchanges and mutual influence between the East and the West.
        4,800원
        2.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Because plastics are cheap and light, their use is indispensable in our daily lives. However, the extensive use of plastics causes the disposal issue. Among various disposal processes, plastic recycling is of great attention because of minimizing waste and harmful byproducts. Herein, we recycle the most popular thermoplastic materials, high-density and low-density polyethylene, producing the anode materials for the Li-ion batteries. The electrochemical properties of the as-recycled soft carbon are investigated to study the energy storage capability as the anode of Li-ion batteries. Our work demonstrates the soft carbon recycled from plastic wastes is a promising anode material.
        4,000원
        3.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The electrochemical properties of a CFX cathode were improved by defluorination of the surface with a N2 plasma and using a silica wafer. Compared to the N2 plasma treatment alone, when the CFX and silica were reacted together, the C-F bonds were modified and the surface was etched efficiently, so defluorination was enhanced. An electrochemical analysis confirmed that Half-cells prepared by treating CFx and silica with nitrogen plasma exhibited a capacity of about 400 mAh/g at 5C. In addition, it was confirmed that the loss of charge transfer was reduced by up to 71% compared to that for pristine CFX. As shown by a GITT analysis, when the CFx and silica were treated with N2 plasma together, the ion conductivity gradually increased due to a decrease in the ion diffusion barriers and the formation of a carbon layer. Therefore, this is a simple and effective way to improve the conductivities of CFX cathode materials with the energy of a N2 plasma and the silica-fluorine reaction.
        4,000원
        4.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Efficient Li-ion transport in anode materials is paramount for electric vehicles (EVs) and energy storage systems. The rapid charging demands of EVs can lead capacity decay at high charging rate. To overcome this challenge, we focus on graphite geometric characteristics that effect to interparticle space. We interpret the correlation between the utilization of the electrode and the interparticle space where solvated Li-ion transports in liquid electrolyte. To introduce variability into this space, two main coke precursors, coal cokes and petroleum cokes, were prepared and further categorized as normal cokes and needle cokes. Manufactured graphite samples were observed with distinct geometric characteristics. In this study, investigates the impact of these geometric variations on electrochemical performance, emphasizing rate capability and cycle stability during fast charging. By analyzing the transport properties of electrochemical species within these graphite samples, we reveal the critical role of morphology in mitigating concentration polarization and side reaction, such as Li-plating. These findings offer promising contribution for the development of advanced anode materials, in fast-charging condition in Li-ion.
        4,000원
        5.
        2024.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, NASICON-type Li1+XGaXTi2-X(PO4)3 (x = 0.1, 0.3 and 0.4) solid-state electrolytes for all-solid-state batteries were synthesized through the sol-gel method. In addition, the influence on the ion conductivity of solid-state electrolytes when partially substituted for Ti4+ (0.61Å) site to Ga3+ (0.62Å) of trivalent cations was investigated. The obtained precursor was heat treated at 450 °C, and a single crystalline phase of Li1+XGaXTi2-X(PO4)3 systems was obtained at a calcination temperature above 650 °C. Additionally, the calcinated powders were pelletized and sintered at temperatures from 800 °C to 1,000 °C at 100 °C intervals. The synthesized powder and sintered bodies of Li1+XGaXTi2-X(PO4)3 were characterized using TGDTA, XRD, XPS and FE-SEM. The ionic conduction properties as solid-state electrolytes were investigated by AC impedance. As a result, Li1+XGaXTi2-X(PO4)3 was successfully produced in all cases. However, a GaPO4 impurity was formed due to the high sintering temperatures and high Ga content. The crystallinity of Li1+XGaXTi2-X(PO4)3 increased with the sintering temperature as evidenced by FE-SEM observations, which demonstrated that the edges of the larger cube-shaped grains become sharper with increases in the sintering temperature. In samples with high sintering temperatures at 1,000 °C and high Ga content above 0.3, coarsening of grains occurred. This resulted in the formation of many grain boundaries, leading to low sinterability. These two factors, the impurity and grain boundary, have an enormous impact on the properties of Li1+XGaXTi2-X(PO4)3. The Li1.3Ga0.3 Ti1.7(PO4)3 pellet sintered at 900 °C was denser than those sintered at other conditions, showing the highest total ion conductivity of 7.66 × 10-5 S/cm at room temperature. The total activation energy of Li-ion transport for the Li1.3Ga0.3Ti1.7(PO4)3 solidstate electrolyte was estimated to be as low as 0.36 eV. Although the Li1+XGaXTi2-X(PO4)3 sintered at 1,000 °C had a relatively high apparent density, it had less total ionic conductivity due to an increase in the grain-boundary resistance with coarse grains.
        4,000원
        6.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Li Shan’s commentary on the Selected Writings appears in 304 of his works, ranging from the Xidufu, an excerpt from the Zuo Zhuan, to the Ritual Essay, Ji Qu Yuan Wen. The Zuo Zhuan records a wide range of topics, from the evolution of history to various rituals, social customs, astronomy and geography, rhymes, proverbs, and a variety of literature. Li Shan’s commentary on the Zuo Zhuan is based on the main text and its content, with citations centered on its main historical events and the origin of its words. On the question of Li Shan’s citation of the Zuo Zhuan notes, we can see through examination that Li Shan was not influenced by the political advocacy of the unification of the Five Classics, and that he took Du’s notes as his main focus and did not exclude the other Zuo Zhuan notes, and in accordance with what is stated in the text of the Selected Works, he thought that it conformed to the wording of the text and made appropriate use of the Fu Qian’s service of the pianist’s notes on the Zuo Zhuan as well as the notes of the other annotators. Among them, the author suspects that Li Shan should have referred to the text of Fu Qian’s “Jie Yi” and Jia Kui’s “ChunQiu ZuoShi JieGu”, while Ma Rong’s words can hardly be said to be a comment from Ma Rong’s “ChunQiu SanZhuan YiTongShuo”, but rather a text quoted from other documents of the time. The contents of Ma Rong’s commentaries in the “Selected Writings” can be found in Kong Yingda’s commentary, which is more detailed than the “Selected Writings” commentary. However, in terms of the “Selected Writings” commentary, especially nowadays, it can be regarded that the commentaries of Li Shan’s commentaries are within the scope of his old commentaries, and it is quite possible that Li Shan cited his old commentaries as commentaries on other works in the case of the same words in his old commentaries in the later years.
        5,700원
        7.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synthesis of extremely competent materials is of great interest in addressing the energy storage concerns. Manganese oxide nanowires ( MnO2 NWs) are prepared in situ with multiwall carbon nanotubes (MWCNT) and graphene oxide (GO) using a simple and effective hydrothermal method. Powder XRD, Raman and XPS analysis are utilized to examine the structural characteristics and chemical state of composites. The initial specific discharge capacity of pure MnO2 NWs, MnO2 NWs/ MWCNT and MnO2 NWs/rGO composites are 1225, 1589 and 1685 mAh/g, respectively. The MnO2 NWs/MWCNT and MnO2 NWs/rGO composites showed stable behavior with a specific capacity of 957 and 1108 mAh/g, respectively, after 60 cycles. Moreover, MnO2 NWs/rGO composite sustained a specific capacity of 784 mAh/g, even after 250 cycles at a current density of 1 A/g showing outstanding cycling stability.
        4,200원
        8.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        N-doping content and configurations have a significant effect on the electrochemical performance of carbon anodes. Herein, we proposed a simple method to synthesize highly N self-doped chitosan-derived carbon with controllable N-doping types by introducing 2ZnCO3 ·3Zn(OH)2 into the precursor. The as-synthesized NC-CS/2ZnCO3·3Zn(OH)2 electrode exhibited more than twice the reversible capacity (518 mAh g− 1 after 100 cycles at 200 mA g− 1) compared to the NC-CS electrode, superior rate performance and outstanding cycling stability. The remarkable improvement should be mainly attributed to the increase of N-doping content (particularly the pyrrolic-N content), which provided more active sites and favored Li+ diffusion kinetics. This study develops a cost-effective and facile synthesis route to fabricate high-performance N self-doped carbon with tunable doping sites for rechargeable battery applications.
        4,000원
        9.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A carbon matrix for high-capacity Li/Na/K-alloy-based anode materials is required because it can effectively accommodate the variation in the volume of Li/Na/K-alloy-based anode materials during cycling. Herein, a nanostructured porous polyhedral carbon (PPC) was synthesized via a simple two-step method consisting of carbonization and selective acid etching, and their electrochemical Li/Na/K-ion storage performance was investigated. The highly uniform PPC, with an average particle size of 800 nm, possesses a porous structure and large specific surface area of 258.82 cm2 g– 1. As anodes for Li/Na/K-ion batteries (LIBs/NIBs/KIBs), the PPC matrix exhibited large initial reversible capacity, fast rate capability (LIB: ~ 320 mAh g– 1 at 3C; NIB: ~ 140 mAh g– 1 at 2C; KIB: ~ 110 mAh g– 1 at 2C), better cyclic performance (LIB: ~ 550 mAh g– 1; NIB: ~ 210 mAh g– 1; KIB: ~ 190 mAh g– 1 at 0.2C over 100 cycles), high ionic diffusivity, and excellent structural robustness upon cycling, which demonstrates that the PPC matrix can be highly used as a carbon matrix for high-capacity alloy-based anode materials for LIBs/NIBs/KIBs.
        4,000원
        14.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Li1.5Al0.5Ti1.5(PO4)3 (LATP) is considered to be one of the promising solid-state electrolytes owing to its excellent chemical and thermal stability, wide potential range (~5.0 V), and high ionic conductivity (~10-4 S/cm). LATP powders are typically prepared via the sol-gel method by adding and mixing nitrate or alkoxide precursors with chelating agents. Here, the thermal properties, crystallinity, density, particle size, and distribution of LATP powders based on chelating agents (citric acid, acetylacetone, EDTA) are compared to find the optimal conditions for densely sintered LATP with high purity. In addition, the three types of LATP powders are utilized to prepare sintered solid electrolytes and observe the microstructure changes during the sintering process. The pyrolysis onset temperature and crystallization temperature of the powder samples are in the order AC-LATP > CA-LATP > ED-LATP, and the LATP powder utilizing citric acid exhibits the highest purity, as no secondary phase other than LiTi2PO4 phase is observed. LATP with citric acid and acetylacetone has a value close to the theoretical density (2.8 g/cm3) after sintering. In comparison, LATP with EDTA has a low sintered density (2.2 g/cm3) because of the generation of many pores after sintering.
        4,000원
        15.
        2023.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, changes in the microstructure and mechanical properties of cast and extruded Al-2Li-1Ce alloy materials were investigated as the Mg content was varied. The density decreased to 2.485, 2.46 and 2.435 g/cm3 when the Mg content in the Al-2Li-1Ce alloy was increased to 2, 4 and 6 wt%, respectively. Intermetallic compounds of Al11Ce3 were observed in all alloys, while the β-phase of Al3Mg2 was observed in alloys containing 6 wt% of Mg. In the extruded material, with increasing Mg content the average grain size decreased to 84.8, 71.6 and 36.2 μm, and the fraction of high-angle grain boundaries (greater than 15°) increased to 82.8 %, 88.6 %, and 91.8 %, respectively. This occurred because the increased Mg content promotes dynamic recrystallization during hot extrusion. Tensile test results showed that as the Mg content increased, both the yield strength and tensile strength increased. The yield strength reached 86.1, 107.3, and 186.4 MPa, and the tensile strength reached 215.2, 285, and 360.5 MPa, respectively. However, it is worth noting that the ductility decreased to 27.78 %, 25.65 %, and 20.72 % as the Mg content increased. This reduction in ductility is attributed to the strengthening effect resulting from the increased amount of dissolved Mg, and grain refinement due to dynamic recrystallization.
        4,000원
        16.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Zhuan Li Wan Xiang Ming Yi’s “Gujinzi” is a typical sample outside the region, and it stores a wealth of thematic corpus. This paper sorts out more than 300 groups of “Gujinzi”, and through the analysis and summary of the style of these materials, it is found that there are not only typical terms marked by the words “Gu” and “Jin”, but also terms such as “Tongshang.” “Shangwen” and “Mouzi” mixed with the typical terms. The collection and identification of its expression style is the premise for further research on the materials of “Gujinzi”, and as an exotic sample of the development of “Gujinzi”, the comparative research on Chinese “Gujinzi” can provide some circumstantial evidence for solving the long-debated problems in the academic history of “Gujinzi”; As an exotic eye, it also provides us with a new perspective to understand the connotation of the traditional term “Gujinzi” and the relationship between words.
        6,000원
        17.
        2023.06 구독 인증기관 무료, 개인회원 유료
        전고체 전지는 전기 자동차의 안정성을 향상시키기 위해 기존의 리튬 이온 전지를 대체할 주요 후보로 간주되고 있 습니다. 그러나 전고체 전지에 사용되는 황화물계 고체 전해질은 산화 환원 안정성이 부족하며 양극복합전극과 표면 에서 부반응을 이르켜 문제를 야기시킵니다. 때문에 양극 표면 코팅법이 제안되었고 이는 충방전 사이클 안정성 및 속도 특성의 개선에 유용한 효과를 나타낼 수 있습니다. 본 논문에서는 결정학적 분석을 통하여 신규 Li-Zr-O 조성 탐색을 하였고, 다양한 양극 소재 코팅소재 후보군 중 리튬 이온 전도체인 Li6Zr2O7 구조가 매우 유망하다는 연구 결 과를 확인했습니다. 본 논문은 기존에 사용되는 LiNbO3, Li4Ti5O12가 아닌 새로운 다양한 구조 및 조성의 양극 코팅 소 재개발에 대한 필요성 및 가능성을 시사합니다.
        4,000원
        18.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Li1.3Al0.3Ti1.7(PO4)3(LATP) is considered a promising material for all-solid-state lithium batteries owing to its high moisture stability, wide potential window (~6 V), and relatively high ion conductivity (10-3–10-4 S/cm). Solid electrolytes based on LATP are manufactured via sintering, using LATP powder as the starting material. The properties of the starting materials depend on the synthesis conditions, which affect the microstructure and ionic conductivity of the solid electrolytes. In this study, we synthesize the LATP powder using sol-gel and co-precipitation methods and characterize the physical properties of powder, such as size, shape, and crystallinity. In addition, we have prepared a disc-shaped LATP solid electrolyte using LATP powder as the starting material. In addition, X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopic measurements are conducted to analyze the grain size, microstructures, and ion conduction properties. These results indicate that the synthesis conditions of the powder are a crucial factor in creating microstructures and affecting the conduction properties of lithium ions in solid electrolytes.
        4,000원
        19.
        2022.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, lanthanum boron silicate glasses were prepared with a composition of x Li2O-(60-x)B2O3-5CaO- 5BaO-7ZnO-10SiO2-10La2O3-3Y2O3 where x = 1,3,5,7, and 9 mol%. Each composition was melted in a platinum crucible under atmospheric conditions at 1,400 °C for 2 h. Clear glasses with a transmittance exceeding 85 % were fabricated. Their optical, thermal, and physical properties, such as refractive index, Abbe number, density, glass transition (Tg) and Knoop hardness were studied. The results demonstrated that refractive index was between 1.6859 and 1.6953 at 589.3 nm. The Abbe number was calculated using an equation for 589.3 nm (nd), 656.3 nm (nf) and 486.1 nm (nc) and was observed to be in the range from 57.5 to 62.6. As the Li2O content increased, the glass transition temperature of the optical glass decreased from 608 °C to 564 °C. If glass mold pressing is performed using a material with a low transition temperature and high mechanical strength, then the optical glasses developed in this study can be completely commercialized.
        4,000원
        20.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        1990년대 초·중반 많은 중국의 화가들은 전통 중국화(中國畵) 의 한계를 극복하기 위해 서양화를 융합하여 자신만의 독특한 회화 스타일과 예술 언어를 나타내었다. 이들 가운데 이고선은 ‘중국화와 서양화의 융합’의 길을 개척한 선두 주자였다. 특히 그의 어(魚)류 회화는 중국 전통 문인화(文人畵)의 필묵 정신을 계승함과 동시에 서양 회화의 형식적인 요소를 받아들여 독창 적인 표현 기법과 예술 언어를 발휘하였다. 본 연구는 이고선 과 동시대 화가들의 어(魚)류를 소재로 한 회화작품에 표현된 미의식과 예술특징의 차이를 알아보고, 중국 당대 사의화(寫意 畵)에 대한 경험과 영향에 대해 분석하였다.
        5,400원
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