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        검색결과 25

        1.
        2024.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Moso bamboo, as a kind of renewable functional material, exhibits outstanding development potential. It is promising to prepare activated carbon with good mechanical strength and high specific surface area using moso bamboo as raw material. In this work, we employed a hydraulic extruder to extrude the bamboo charcoal and the adhesive to obtain the moso bamboo activated carbon, and improved the specific surface area of the columnar activated carbon through high-temperature water vapor activation. Through the catalytic role of the water vapor activation process, the formation and expansion of the pores were promoted and the internal pores were greatly increased. The obtained columnar activated carbon shows excellent mechanical strength (93%) and high specific surface area (791.54 m2/ g). Polyacrylamide@asphalt is one of the most effective adhesives in the high-temperature water vapor activation. The average pore size (22.99 nm) and pore volume (0.36 cm3/ g) of the prepared columnar activated carbon showed a high mesoporous ratio (83%). Based on the excellent pore structure brought by the activation process, the adsorption capacity of iodine (1135.75 mg/g), methylene blue (230 mg/g) and carbon tetrachloride (64.03 mg/g) were greatly improved. The resultant moso bamboo columnar activated carbon with high specific surface area, excellent mechanical properties, and outstanding adsorption capacity possesses a wide range of industrial applications and environmental protection potential.
        4,600원
        2.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In response to the growing demand for high-performance lithium-ion batteries, this study investigates the crucial role of different carbon sources in enhancing the electrochemical performance of lithium iron phosphate ( LiFePO4) cathode materials. Lithium iron phosphate ( LiFePO4) suffers from drawbacks, such as low electronic conductivity and low lithium-ion diffusion coefficient, which hinder its industrial development. Carbon is a common surface coating material for LiFePO4, and the source, coating method, coating amount, and incorporation method of carbon have a significant impact on the performance of LiFePO4 materials. In this work, iron phosphate was used as the iron and phosphorus source, and lithium carbonate was used as the lithium source. Glucose, phenolic resin, ascorbic acid, and starch were employed as carbon sources. Ethanol was utilized as a dispersing agent, and ball milling was employed to obtain the LiFePO4 precursor. Carbon-coated LiFePO4 cathode materials were synthesized using the carbothermal reduction method, and the effects of different carbon sources on the structure and electrochemical performance of LiFePO4 materials were systematically investigated. The results showed that, compared to other carbon sources, LiFePO4 prepared with glucose as the carbon source not only had a higher discharge specific capacity but also better rate cycle performance. Within a voltage range of 2.5–4.2 V, the initial discharge specific capacities at 0.1, 0.5, and 1 C rates were 154.6, 145.6, and 137.6 mAh/g, respectively. After 20 cycles at a 1 C rate, the capacity retention rate was 98.7%, demonstrating excellent electrochemical performance.
        4,000원
        3.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The challenge of incorporating photothermal conversion function into chitosan (CS) hybrid fibers lies in balancing functionality and mechanical properties. In this study, we successfully prepared a chitosan/graphene oxide/gelatin (CS/GA/GO) hybrid fiber using the wet spinning process, achieving improved mechanical properties and efficient photothermal conversion capabilities. When compared with pure CS fiber with a breaking strength of 1.07 cN/dtex, the breaking strength of the CS/ GA composite fiber increased by 46.73%, while the CS/GA/GO hybrid fiber showed an even greater increase of 85.98%. In addition, the introduction of gelatin (GA) led to secondary scattering of near-infrared light, enhancing the photothermal conversion efficiency. As a result, the CS/GA/GO hybrid fiber exhibited a faster temperature rise rate and higher maximum temperatures (94.3 °C, 103.0 °C, and 111.3 °C) as compared to the CS/GO hybrid fiber. The successful incorporation of GA not only improved the mechanical properties but also enhanced the photothermal performance of the hybrid fiber.
        4,200원
        4.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Polylactic acid (PLA) is often used in the preparation of environmentally friendly biodegradable polymer plastics, and how to improve the flame retardant performance of polylactic acid has been concerned by experts and scholars. Here, we provide a new idea, using bamboo activated carbon as the main material, and phytic acid, urea and Zn(NO3)2·6(H2O) as modifiers to produce a new type of carbon flame retardant. It has bamboo activated carbon as carbon source; second, it has P, N elements and metal oxides. The two synergistically play a flame retardant role on polylactic acid. The polylactic acid composite showed good thermal stability, from no grade optimization to V-0 in the UL-94 test, and the limiting oxygen index was also increased from 20.1 to 31.2%. The above tests show that bamboo activated carbon loaded with ZnO has a good flame retardant effect on polylactic acid.
        4,200원
        6.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Energy and environmental are always two major challenges for the sustainable development of the modern human being. For avoiding the serious environmental pollution caused in the fabrication process of porous carbon, a popular energy storage material, we reported a facile, green and activating agent free route hereby directly carbonizing a special biomass, Glebionis coronaria. A nitrogen doped hierarchical porous carbon with a specific surface area of up to 1007 m2 g−1 and a N doping content of up to 2.65 at.% was facilely fabricated by employing the above route. Benefiting from the peculiarly hierarchical porous morphology, enhanced wettability and improved conductivity, the obtained material exhibits superior capacitance performance, which capacitance reaches up to 205 F g−1 under two-electrode configuration, and no capacitance loss is observed after 5000 cycles. Meanwhile, the capacitance retention of the obtained material arrives up to 95.0% even under a high current density of 20 A g−1, illuminating its excellent rate capability. The fabricated nitrogen-doped hierarchical porous carbon with larger capacitance than commercial activated carbon, excellent rate capability and cycle stability is an ideal cost-efficient substitution of commercial activated carbon for supercapacitor application.
        4,000원
        7.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        「딸을 위한 기도」는 문학사에서 딸에 관한 시로 가장 유명한 시들 중의 하나이다. 그러나 딸이 이 시의 유일한 주제인가? 본 논문은 예이츠 자신의 자기투영의 관점에서 이 시의 이면에 깔린 부차적 텍스트를 다시 읽어내는데, 이 시에서, 딸의 미래에 대한 아버지라는 표면적 맥락에서의 기법을 사용하지만, 예이츠 자신의 과거, 현재와 미래, 자신의 나이 들어가는데 대한 걱정, 그리고 초월과 지혜의 추구 등에 대한 이 시의 부차적 텍스트가 발견되는데 그것들을 짚음으로써 그 질문에 답하려 한다.
        4,800원
        8.
        2019.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implement compatible optics systems. Simultaneous dual/multi-frequency VLBI observations at mm wavelengths with international baselines are thus possible. In this paper, we present the results from the first successful simultaneous 22/43 GHz dualfrequency observation with KaVA(KVN and VERA array), including images and astrometric results. Our analysis shows that the newly implemented simultaneous receiving system has brought a significant extension of the coherence time of the 43 GHz visibility phases along the international baselines. The astrometric results obtained with KaVA are consistent with those obtained with the independent analysis of the KVN data. Our results thus confirm the good performance of the simultaneous receiving systems for the non-KVN stations. Future simultaneous observations with more global stations bring even higher sensitivity and micro-arcsecond level astrometric measurements of the targets.
        4,000원
        9.
        2018.07 구독 인증기관·개인회원 무료
        Introduction The study chooses smartphone applications which have update experience as the study case to analysis if it will cause customer attrition. Application updates aims to make up the bugs which may cause bad effects on using, while in fact, most changes will be resisted by customers. We adapt three elements to collect data about the attitude of customers toward applications update, the conclusion illustrates, customers will resist changes in some conditions and cause customers attrition. Therefore, application developers should focus on the personal emotional reaction and cognitive evolution as well as predict what may influence the customers normal use after the applications update to make correct update decisions. In order to define the relationship between variable and result., we take smartphone application which had experienced update as examples and choose fsQCA as the methodology to analysis. Literature Review Resistance to change is a psychological process, Brehm(1966)claims customers resist to change origins from their believe that they have rights to control free, when this rights be challenged, this resistance behavior will happen due to they want to protect their own rights. Some scholars distinguished the concept of resistance to change: when receptors in the low involvement or limited cognize, their resistance behaviors is likely to be considered as the passive resistance; otherwise, the behaviors would be recognized as active resistance (Nabih,1997). Bagozz and Lee(1999) think that functional barrier is an important factors which influence the degree of innovation receptance, when customers think products after update cannot meet their function needs will cause resistance to change. Resistance always occur passively, bemuse of the disturb of the former habits of using (Ram &Sheth 1989), and former studies also indicate that prejudice towards changes is one of significant factors. Because changes are uncertainty, Fiske and Taylor(1991)claims that uncertainty can make people hate changes and Whitson and Galinsky(2008)consider aversion will be the strong driver of resistance to change to reduce uncertainty and risk. In terms of a company, the cost of maintaining a old customer is much lower than these of develop a new user, Actually, customer attrition is response of entrepreneur revenue and the vital section in development of companies. The famous american honesty management scholar Frederic Reichheld’s research indicates that when the extension of the commercial relationship of entrepreneur and customers, companies can acquire fatter profit through the relationship. Conclusions This study chooses fsQCA as methodology to define the relationship between resistance to change and customer attrition instead of using structural equation modeling. Sometimes, even customers have right cognitive evolution towards changes, when they find their efficiency be influenced by it, they also resist to change; while adverse emotional reaction also has an adverse effect on customer retention though they build positive cognitive evolution about changes. there is a remain circumstance of lossing of customers that when customers hate changes and they find their efficiency be influenced by update, the honesty of this product will also decrease. This three condition all contribute to customers attrition which should be paid more attention by companies.
        10.
        2016.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Following its jurisdictional decision in October 2015, the arbitral tribunal constituted under Annex VII to the UNCLOS issued its final award on July 12, 2016 in the South China Sea Arbitration case. It found overwhelmingly in favor of the Philippines. This article comments on two of the flaws regarding the issue of jurisdiction arising from both preliminary and final awards of the case. It firstly calls into question the inconsistent standard adopted in identifying jurisdictional obstacles, and finds a projurisdictional bias in the Tribunal’s awards. It further analyses the fallacious approach of fragmenting the maritime delimitation disputes, and suggests the legal conundrum of status and entitlement of maritime features related to Sino-Philippine sea boundary delimitation should not constitute a separate dispute subject to legal proceedings. By purposefully downplaying jurisdictional obstacles and exercising powers on false disputes, the tribunal raises doubts to its legitimacy.
        5,100원
        13.
        2009.08 구독 인증기관·개인회원 무료
        Grazing restoration succession of the degraded grassland is an important aspect in community ecology. Field experiment was carried out to examine how major species restore in first four years restoration following 11 consecutive grazing under different stocking rates in Inner Mongolian steppe. A. frigida and P. acaulis are the most important two species in the all treatments (NG, LG, MG and HG) after four years restoration, although they had high fluctuation. The biomasses of these two species account for 40-90% of total biomass. Especially in no grazing area, which was exclosured since 1990, A. frigida and P. acaulis are still the most important two species in the community. These results suggested A. frigida and P. acaulis conununity are quite stable, and will keep long-time if no special measurements were taken during the restoration of the degraded grassland.
        14.
        2009.08 구독 인증기관·개인회원 무료
        In this paper, the effect of different land-use types on soil organic carbon (SOC) and Particulate Organic Carbon(POC) was studied by analyzing the soils in the meadow and conversing land of grassland to cropland in ecotones of agriculture and animal husbandry. It is shown t㏊t, compared with meadow, rotations of P/O and P/Cwill reduce SOC in 0-30㎝ soil layers by 47.54%-65.11% and 34.16-64.26% and POC by 16.90%-24.48% and 11.94%-20.29%, respectively. And SOC in meadow is more t㏊n in conversing land of grassland to cropland (P<0.05). Conversing grassland to cropland in ecotones of agriculture and animal husbandry will decrease the contents of SOC and POC.
        15.
        2009.08 구독 인증기관·개인회원 무료
        The research was conducted at a degraded steppe in Saibei Adiministrative Region of ZhangJiakou in Hebei province. Four patches dominated by fringed sagebrush (Artemisia frigida), narrowleaf stellera (Stellera chamaejasme), shining speargrass (Achnatherum splendens), white swordflag (Iris lactea), respectively, were sampled. Phosphorus (P) was applied at four levels (0, 5, 10 and 15㎎ ㎏?¹ soil) in each patch. The mycorrhizal infection rate in Stellera chamaejasme species and Achnatherum splendens species was low, differed from other two patches of Artemisia frigid and Iris lactea.
        16.
        2009.08 구독 인증기관·개인회원 무료
        Forage production and water use efficiency (WUE) of Lucerne were investigated in three varieties at different water availabilities. Forage production decreased with the severity of soil water availability. At 50% field water capacity (FWC), forage production dropped but in two varieties, Algonquin and Longdong, was still high and from 75%FWC to 50%FWC, forage production in Longdong decreased at the least rate. The greatest leaf WUE was observed in Longdong at all soil water availabilities. From 75%FWC to 50%FWC, it increased in Longdong and Xinjiangdaye, but decreased in Algonquin. With the severity of water deficit, δ¹³C value increased in all three varieties. At the same water availability, the greatest value was observed in Longdong. It suggested that moderate water stress can improve WUE in Lucerne. Longdong is to some extent more efficient in water use and may be more drought-tolerant with more steady production at moderate water deficit.
        17.
        2007.10 구독 인증기관 무료, 개인회원 유료
        To design an efficient and acceptable indoor air environment in a badminton gymnasium, it is important to study the velocity and temperature field in the conditioned room. For diverse airflow patterns, the k- c models with wall function near solid boundaries are adopted to simulate airflow distribution in the gymnasium. The simulated result is analyzed in this paper, and it provides the important reference for the design of air condition system and optimization of the project. CFD is effective design tool for air flow in large space, for it can give the velocity and temperature values at any point quantitatively.
        3,000원
        20.
        2020.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The purpose of this study is to analyze the efficiency of research institutes of futures companies, and to promote the development of futures market and real economy. This study employs DEA-solver software to conduct super-efficiency data envelopment analysis (SE-DEA), and also selects 40 representative futures research institutes in China as decision-making units (DMUs). For data of input and output indicators, we collect from the China Futures Association, Futures Daily, Hexun.com and Webstock.com respectively, and the time duration is the 103 trading days between from October 2019 to February 2020. Then the indicator for the strategy accuracy rate is calculated separately by analyzing the strategies published by each DMUs in public media. In conclusions, most institutes have excessive investment in human resources, and also have insufficient strategy accuracy rate and insufficient published research reports. The findings of this study suggest that Chinese futures companies need to improve the efficiency of research institutes, and better meet the demand of the financial market. In fact, the analysis of the efficiency of the futures company research institute has not been found in the literature worldwide, Application of DEA model in efficiency analysis of securities and futures research institutions and establishment of indicators are the innovations of this paper.
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