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        검색결과 29

        1.
        2024.12 구독 인증기관 무료, 개인회원 유료
        In the field of oscillating hydrofoil research, the choice of hydrofoils is still mainly based on traditional NACA airfoils. The article explores the hydrodynamic characteristics of other airfoil structures to further improve the applicable range of hydrofoil working environments. By applying the swept structure of fish tail fins through biomimetic methods to oscillating hydrofoils, a motion model of the swept oscillating hydrofoil is established, and the relevant mathematical expressions and parameter definitions are described. Through numerical simulation methods, the effects of the pitch axis position and the tip-to-root ratio on the performance of the swept oscillating hydrofoil are analyzed. The simulation results show that the pitch axis position has a significant impact on the various force characteristics and energy acquisition efficiency of the hydrofoil, while the tip-to-root ratio mainly reflects the degree of sweep of the hydrofoil, thereby affecting the lift-to-drag ratio and the moment coefficient of the swept hydrofoil. Selecting the appropriate pitch axis position and tip-to-root ratio will enhance the lift of the hydrofoil while reducing the drag experienced.
        4,000원
        2.
        2024.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Silicon carbide (β-SiC) was synthesized through an improved sol–gel method, then Ni/SiC catalysts were prepared using a hydrothermal method. The catalysts were characterized using TEM, H2- TPR, CO2- TPD and N2- TPD, etc. The results showed that the synthesized β-SiC had a large specific surface area, promoting the dispersion of Ni species and thus exposing more active sites. The interaction between Ni species and β-SiC contributed significantly to catalytic performance. Furthermore, the strong alkalinity of catalyst could adjust the bond energy of the active metal and N (M–N), which were conducive to desorption of the recombinant N2 from the metal surface, promoting to ammonia decomposition. Among the Ni/SiC catalysts, 30Ni/SiC-700 synthesized with the Ni loading of 30 wt% and calcination temperature of 700 °C, exhibited the optimal ammonia conversion rate of 93.4% at 600 °C under the space speed of 30,000 mL∙gcat −1∙h−1, and demonstrated a long-term stability, suggesting a very promising catalyst in ammonia decomposition.
        4,200원
        3.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        사범대학 학생은 대학생일 뿐만 아니라 미래의 교사로서 자신의 핵심 소양을 향상시킬 뿐만 아니라 학생의 핵심 소양을 발전시키는 중요한 책 임을 져야 한다. 본 논문의 연구 목적은 사범생의 직업적 인식이 핵심 소양에 미치는 영향을 조사하는 것이다. 연구 방법은 정량적 연구 방법 과 SPSS 26.0 통계 소프트웨어를 사용하여 데이터를 분석하였다. 연구 결과는 사범생의 직업 정체성과 핵심 소양 사이에 유의미한 정적 상관관 계가 있음을 보여주며, 직업적 정체성의 각 차원은 핵심 소양에 예측 효 과가 있는 것을 보여 주었다. 이 연구를 통해 우리는 사범생의 핵심 소 양 형성에 영향을 미치는 요인과 메커니즘을 찾고 사범생의 인재 양성과 기초 교육 발전을 향상시키기 위한 이론적 참고 자료를 제공한다.
        5,800원
        5.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study systematically investigated the efficacy of incorporating graphene/cerium hydroxide (GH) composite material into epoxy-modified polyurethane resin coatings for enhancing the corrosion resistance of Q690qE steel within polluted marine atmospheric conditions. The research encompassed a range of electrochemical assessments and analyses. Notably, the E/GH-0.3% coating displayed a substantially positive open-circuit potential (OCP) and prominently reduced corrosion current density, leading to annual corrosion rates of 2.72 mm/a following 25 days of immersion. Electrochemical impedance spectroscopy (EIS) elucidated the superiority of the E/GH-0.3% coating, characterized by the highest impedance modulus |Z| at 0.1 Hz, indicative of robust corrosion protection. Remarkably, the self-healing performance of E/GH-0.3% and E/ GH-0.5% coatings was evidenced by the formation of a composite passivation layer at scratch sites, particularly pronounced after 40 days of immersion. These findings underscore the promising potential of the GH composite as an effective corrosion inhibitor, holding significant promise for the advancement of protective coatings in harsh coastal industrial environments.
        4,000원
        6.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To solve the problem of water pollution, researchers have proposed a photocatalytic degradation technology, in which the key factor is the development of efficient photocatalytic materials. Graphitic carbon nitride (g-C3N4), an n-type semiconductor, has been widely studied due to its suitable band gap (2.7 eV), low cost, easy preparation, non-toxicity, and high photostability. However, the pure-phase g-C3N4 still has defects such as low specific surface area, insufficient visible light absorption, low charge mobility, few active sites for interfacial reaction, and easy recombination of photogenerated electron–hole pairs, which leads to the lower photocatalytic activity of g-C3N4. Aiming at the problems mentioned above, this paper focus on the synthesis of g-C3N4-based composites with high photocatalytic activity via lemon juice induction method. Thiourea and lemon juice were selected as precursors, and carbon quantum dots (CQDs) as electron mediators were introduced anchoring on the surface of g-C3N4 to build g-C3N4/CQDs with compact interface. The results showed that small-sized CQDs are uniformly distributed on the surface of g-C3N4, and the g-C3N4/CQDs composite has a 2D0D structure, which reduces the recombination of photogenerated electron–hole pairs. The photocatalytic degradation efficiency of 4% g-C3N4/CQDs for RhB reaches the highest data of 90.9%, and the photocatalytic degradation rate is 0.016 min− 1, which is about 2.3 times that of g-C3N4. After four cycles of photocatalytic reaction, the photocatalytic degradation efficiency of the material remained at 81.7%. Therefore, the g-C3N4/CQDs synthesized via lemon juice induction has a more stable microstructure, and the charge separation efficiency is greatly improved, which is suitable for practical photocatalytic environmental protection.
        4,300원
        7.
        2022.03 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        원남과 티베트는 중국 남서 국경 지역에 위치하고, 여러 민족과 종교가 혼재되어 있어 중국정부가 통치하는데 많은 어려움을 겪고 있다. 또한 국 경선의 길이가 길어 국가의 중요한 방어구역이기도 하다. 하지만 이 지역 에 대한 학계의 관심과 연구는 상대적으로 빈약하다. 이러한 상황에서 본 논문은 이 지역들의 소속민족의 발전 및 건설 그리고 이들 지역의 고토수 비(守土固边)에 대해 연구한다. 문헌연구를 통해 국가안보차원에서 소수 민족 마을에 대한 건설과 고토수비현황에 대해 기초시설, 경제발전, 민생 발전, 생태문명 등 네 가지 분야로 깊이 고찰한 다음, 이를 통해 문제점을 발견하고 해결책과 발전방안을 제시하였다.
        9,000원
        8.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The remarkable electrical, thermal, mechanical, and optical properties of graphene and its derivative grapheme oxide have recently gained great importance, along with the large surface area and single-atoms thickness. In this respect, several techniques of synthesis such as chemical exfoliation, mechanical exfoliation, or chemical synthesis have been discovered. However, the development of graphene with fewer defects and on a large scale poses major challenges; therefore, it is increasingly necessary to produce it in large proportions with high quality. This paper reviews the top-down synthesis approach of graphene and its well-known derivative graphene oxide. Furthermore, characterization of graphene oxide nanomaterial is a critical component of the analysis. The characterization techniques employed to determine the quality, defects intensity, number of layers, and structures for graphene oxide nanomaterial at the atomic scale. This article focuses on the different involved characterization methodology for graphene oxide with their percentage utilization for the past 11 years. Additionally, reviewing all of the characterization literature for the last 11 years would be a difficult task. Therefore, the aim is to outline the existing state of graphene oxide by different characterization techniques and provide a comparative analysis based on their percentage utilization.
        8,700원
        9.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated whether a tool such as a game toy can be used as an augmented reality tool, and a system model that can be extended to a game element using wireless communication technology such as Bluetooth and a controllable module. This is an online ship type game using augmented reality technology and wireless communication technology. In addition, the existing game element was extended by applying a smartphone app control module. The existing game method uses the method of playing the game with only limited functions in the same space. This study expands to augmented reality-based games by implementing contents in a way that matches game objects with the grafting of augmented reality technology, and uses various items that emerge as the limit of reality. Therefore, we standardized the size of game objects so that they can be used three-dimension in all spaces on the screen according to the space arrangement such as overlapping prevention, distance, and height, and augmented reality technology was used to allow the game to be played by manipulation of a smartphone. In addition, we propose a system framework-based model that can be applied to various games, and a framework that can implement various augmented reality environments. The augmented reality-based battle game proposed in this study combines a knowledge-based augmented reality system that can be extended to game elements by modularizing the function of a toy through+ a context-aware agent based on context information and an intelligent DB based on domain knowledge.
        4,300원
        10.
        2020.11 구독 인증기관 무료, 개인회원 유료
        The paper measures and predicts the performance of online auxiliary channel of movies released in China. Based on the signaling theory, the paper confirms that online movie consumption is generally informed by the box-office revenue of the same movie, with genres as important moderators.
        4,000원
        12.
        2020.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In the molecular cloud G33.92+0.11A, massive stars are forming sequentially in dense cores, probably due to interaction with accreted gas. Cold dense gas, which is likely the pristine gas of the cloud, is traced by DCN line and dust continuum emission. Clear chemical differences were observed in different source locations and for different velocity components in the same line of sight. Several distinct gas components coexist in the cloud: the pristine cold gas, the accreted dense gas, and warm turbulent gas, in addition to the star-forming dense clumps. Filaments of accreted gas occur in the northern part of the A1 and A5 clumps, and the velocity gradient along these features suggests that the gas is falling toward the cloud and may have triggered the most recent star formation. The large concentration of turbulent gas in the A2 clump seems to have formed mainly through disturbances from the outside.
        4,000원
        13.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Plasma-sprayed HA coatings on metallic implants are widely used for clinical applications. However, typical lamellar structure along with plasma-sprayed coatings usually leads to weak inter-splat adhesion and impair their mechanical properties. In this research, graphene nanosheet (GNS) reinforced HA coatings were fabricated using plasma spray; these GNSs retained their original structure and distributed homogeneously in the as-sprayed coatings. On the basis of instrumented microindentation tests with and without multiple partial unloading, as compared with the monolithic HA coating, the inter-splat friction force increased by ~ 8.7% for the 1.0 wt% GNS/HA coating, and it slightly decreased to ~ 6.5% for the 2.0 wt% GNS/ HA coating due to GNS agglomeration. Meanwhile, the added GNSs contributed greatly to the indentation yield strength of the HA coatings. These results illustrated that these embedded GNSs at splat boundaries are potential in splat-boundary strengthening and resisting splat sliding.
        4,000원
        14.
        2018.07 구독 인증기관 무료, 개인회원 유료
        This paper studies the impact of retailer dominance on the product line design in a distribution channel. We revisit the elegant framework proposed by Villas-Boas (1998) in which a manufacturer sells his products through an independent retailer to heterogeneous consumers. We show that retailer dominance may completely eliminate the possibility of product line offering, irrespective of whether retailer dominance takes the form of price leadership or quality leadership. In addition, when consumers are sufficiently heterogeneous, product line offering may benefit the manufacturer without sacrificing the retailer’s profit, thereby creating Pareto improvement along the distribution channel. Given this Pareto improvement, retailer dominance may lead to an upward-distorted quality and the possibility of product line extension compared with either the integrated channel or the case with a weak retailer. Retailer competition does not necessarily restore the incen-tive to offer the product line, but may generate either quality degradation or quality enhancement. Our analysis establishes a threshold policy on the consumer composition for the retailer to pursue the price or quality leadership.
        5,400원
        16.
        2018.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Soybean straw (SS)-based activated carbon was employed as a precursor to prepare carbon molecular sieves (CMSs) via chemical vapor deposition (CVD) technique using methane as carbon source. Prior to the CVD process, SS was activated by 0.5 wt% ZnCl2, followed by a carbonization at 500°C for 1 h in N2 atmosphere. N2 (77 K) adsorption-desorption and CO2 (273 K) adsorption tests were carried out to analyze the pore structure of the prepared CMSs. The results show that increasing the deposition temperature, time or methane flow rate leads the decrease in N2 adsorption capacity, micropore volume and average pore diameter of CMSs. The adsorption selectivity coefficient of CO2/CH4 achieves as high as 20.8 over CMSs obtained under the methane flow rate of 30 mL min–1 at 800°C for 70 min. The study demonstrates the prepared CMSs are a candidate adsorbent for CO2/CH4 separation.
        4,000원
        17.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the in vitro biocompatibility of graphene film (GF) with osteoblasts was evaluated through cell adhesion, viability, alkaline phosphatase activity, F-actin and vinculin expressions, versus graphite paper as a reference material. The results showed that MG-63 cells exhibited stronger cell adhesion, better proliferation and viability on GF, and osteoblasts cultured on GF exhibited vinculin expression throughout the cell body. The rougher and wrinkled surface morphology, higher elastic modulus and easy out-of-plane deformation associated with GF were considered to promote cell adhesion. Also, the biomineralization of GF was assessed by soaking in simulated body fluid, and the GF exhibited enhanced mineralization ability in terms of mineral deposition, which almost pervaded the entire GF surface. Our results suggest that graphene promotes cell adhesion, activity and the formation of bonelike apatite. This research is expected to facilitate a better understanding of graphene-cell interactions and potential applications of graphene as a promising toughening nanofiller in bioceramics used in load-bearing implants.
        4,000원
        18.
        2016.07 구독 인증기관·개인회원 무료
        This study examines when high tech firms are better off specializing in either exploration or exploitation learning strategy. Drawing on the organizational learning literature, we hypothesize that a firm’s imbalance between exploration and exploitation (or specialization strategy) has differential impacts on firm performance depending on its structural characteristics and external environment. A survey data of 180 high tech firms in China shows that firm age and scarcity of R&D resources moderate the relationship between specialization and business performance. Moreover, specialization strategy works better when competitive intensity is low.
        19.
        2014.07 구독 인증기관 무료, 개인회원 유료
        According to theory of consumer contamination (Argo, Dahl & Morales, 2006), a product, after being touched by a customer, will be disgusted and devalued by the following customer. However, Argo, et al. (2006) considered only a high salience of contact product, i.e., T-shirts, and did not consider low salience of contact products. This study extended the study of Argo, et al. (2006) and examined whether perception of consumer contamination varies between products of different saliences of contact. The gender difference was also considered. The result from an experiment showed that consumers’ reactions to ‘contaminated’ products vary, depending on the salience of contact. The result also shows that female consumers tend to be more sensitive to consumer contamination.
        3,000원
        20.
        2014.07 구독 인증기관·개인회원 무료
        This study explores the relationship among brand experience, consumer satisfaction and brand loyalty with virtual experience and the virtual community as the intervening variables. We intend to discuss how the new concept of ‘brand experience’ impacted by the internet environment. We integrate the following new research subjects together: brand experience, virtual experience and virtual community. As the research purpose is to understand the effects of virtual environments on brand experience on consumer satisfaction and on brand loyalty, it takes virtual experience as the intervening variable to discuss whether it positively or negatively influences the relationship between brand experience and consumer satisfaction, and takes the virtual commodity variable as the intervening variable to discuss whether it positively or negatively influences the relationship between consumer satisfaction and brand loyalty. This study takes the virtual community members of apple brand in taiwan as the research subjects and 516 questionnaires were completed and returned. The results show that the brand experience had a positive effect on the consumers’ satisfaction and brand loyalty. In addition, the virtual experience has a positive moderating effect on the relationship of brand experience and consumer satisfaction. Finally, this study also discovered that the virtual community also has a positive moderating effect on the relationship between consumers’ satisfaction and brand loyalty.
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