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        검색결과 117

        6.
        2025.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 중국상업은행을 대상으로 COVID-19로 인한 위기를 극복하는 과정에 긍정적인 영향 을 미친 변수가 무엇인지를 분석하였다. 이를 위해 분석표본을 대상으로 맘퀴스트지수 (Malmquist index) 생산성 분석을 실시하여 COVID-19 전후 생산성이 모두 양호했던과 모두 불량했던 그룹 으로 구분한 후, 각 그룹별로 패널 (panel) 분석을 수행하여 수익성 결정요인을 비교하였다. 주요 분석결과는 다음과 같다. COVID-19 전후 지속적으로 높은 생산성을 유지한 중국상업은행 은 자산건전성이 높을수록, 수지비율이 낮을수록, 규모가 작을수록 그리고 이자수익이 높을수록 수 익성에 긍정적인 영향을 발휘하여 COVID-19를 극복한 것으로 확인되었다. 이는 두 그룹 간 생산 성변화 차이가 은행의 경영자원 배분과 경영특성에 의한 것임을 시사한다. 향후 중국상업은행은 수 익구조 개선, 비즈니스 모델의 혁신, 디지털전환에 대한 적극 대응을 해나가야만 지속가능한 성장 을 도모할 수 있을 것이다.
        6,700원
        7.
        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
        8.
        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
        12.
        2024.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this paper, iron ore tailings (IOT) were separated from the tailings field and used to prepare cement stabilized macadam (CSM) with porous basalt aggregate. First, the basic properties of the raw materials were studied. Porous basalt was replaced by IOT at ratios of 0, 20 %, 40 %, 60 %, 80 %, and 100 % as fine aggregate to prepare CSM, and the effects of different cement dosage (4 %, 5 %, 6 %) on CSM performance were also investigated. CSM’s durability and mechanical performance with ages of 7 d, 28 d, and 90 d were studied with the unconfined compression strength test, splitting tensile strength test, compressive modulus test and freeze-thaw test, respectively. The changes in Ca2+ content in CSM of different ages and different IOT ratios were analyzed by the ethylene diamine tetraacetic acid (EDTA) titration method, and the micro-morphology of CSM with different ages and different IOT replaced ratio were observed by scanning electron microscopy (SEM). It was found that with the same cement dosage, the strengths of the IOT-replaced CSM were weaker than that of the porous basalt aggregate at early stage, and the strength was highest at the replaced ratio of 60 %. With a cement dosage of 4 %, the unconfined compressive strength of CSM without IOT was increased by 6.78 % at ages from 28 d to 90 d, while the splitting tensile strength increased by 7.89 %. However, once the IOT replaced ratio reached 100 %, the values increased by about 76.24 % and 17.78 %, which was better than 0 % IOT. The CSM-IOT performed better than the porous basalt CSM at 90 d age. This means IOT can replace porous basalt fine aggregate as a pavement base.
        4,300원
        13.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cu2+/polyacrylonitrile composite fibers were prepared by electrospinning, and then Cu/carbon nanofibers (denoted as Cu/ CNF-X; X = Cu content, 0, 3, or 5 wt%) were formed by calcining them. The effects of Cu2+ content and carbonization temperature on the conductivity and electrothermal conversion of Cu/CNF-X were investigated. The results revealed that the conductivity and electrothermal properties of Cu/CNF-X improve with the increase in the Cu2+ content and carbonization temperature. When the carbonization temperature was 800, 900, or 1000 °C, the conductivity of Cu/CNF-5 (0.08, 0.68, or 2.48 S/cm, respectively) increased to 1.6, 1.5, or 1.6 times that of Cu/CNF-0, respectively. The highest instantaneous surface temperatures of Cu/CNF-5 calcined at 800, 900, and 1000 °C (36, 145, and 270.2 °C, respectively) increased by 4, 25.5, and 44.6 °C, respectively, compared with those of the corresponding Cu/CNF-0 samples (32, 120.3, and 225.6 °C, respectively). Thus, the addition of a small amount of Cu2+ effectively improved the conductivity and electrothermal conversion performance of Cu/CNF-X, which has potential application value in industrial products in the future.
        4,000원
        14.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Heavy metal ions pollution has become of worldwide critical concern, thus, it is particularly important to monitor it in the environment and food for ensuring human health. In this study, p-phenylenediamine and 2-mercaptothiazoline were used to prepare nitrogen (N) and sulfur (S) co-doped carbon dots (N/SCDs) for fluorescent and colorimetric detection of Cu2+. The fabricated N/SCDs with bright green fluorescence showed excellent optical characteristics and favorable water solubility. In an aqueous system, a significant fluorescence quenching of N/SCDs at 512 nm is obtained in the presence of Cu2+. It also caused a significant colorimetric response with the color of prepared N/SCDs solution changed from colorless to yellow. Under optimal conditions, the analytical results showed that the linear range spanning from 5 to 400 μM, with a detection limit of 0.215 μM in fluorescence and 0.225 μM in colorimetric detection. In addition, N/SCDs displayed high selectivity toward Cu2+. No obvious interference was observed over other metal ions. Furthermore, we have also used N/SCDs to monitor Cu2+ in tap and lake water. The recovery of Cu2+ ranged between 89.6% and 113.1%. Exhibiting remarkable sensitivity and selectivity, the designed sensor offers a promising detection method for Cu2+ detection in the real sample.
        4,000원
        15.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A series of ZIF-67-C-IL catalysts were prepared using ZIF-67 and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([ BMIM]NTf2) ionic liquid as precursors. The structure of the catalysts was characterized by XRD, TEM, SEM and XPS. The catalytic performance of the catalysts for the oxygen reduction reaction (ORR) was evaluated in a three-electrode system. The results confirmed that the high-temperature treatment of the precursors resulted in the formation of N, S codoped carbon-encapsulated Co9S8 nanoparticles. To create N, S co-doped carbon coated Co9S8 nanoparticle catalysts, ionic liquids are used as sulfur and nitrogen sources. The catalytic activity of ORR can be improved using N, S co-doped carbon to prevent the aggregation of Co9S8 nanoparticles. Graphitized and N, S co-doped carbon shells are optimal for achieving high activity stability. Optimal 600-ZIF-67-C(1:1.5)-30IL catalytic activity was observed for ORR. The half-wave potential of ORR was 0.88 V vs. RHE in 0.1 mol L− 1 KOH, with a limit current density of 4.70 mA cm− 2. Similar ORR electrocatalytic activity was observed between this catalyst and commercial Pt/C (20 wt%).
        4,000원
        16.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: The abdominal drawing-in maneuver (ADIM), a method of lumbar stabilization training, is an effective neuromuscular intervention for lumbar instability associated with low back pain (LBP). Objects: The purpose of this study was to compare the effect of a 2-week period of the ADIM and tensor fasciae latae-iliotibial band (TFL-ITB) self-stretching on lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL-ITB length, and pain intensity during active prone hip lateral rotation. Methods: Twenty-two subjects with lumbar extension rotation syndrome accompanying shortened TFL-ITB (16 males and 6 females) were recruited for this study. The subjects were instructed how to perform ADIM training or ADIM training plus TFL-ITB self-stretching program at home for a 2-week period. A 3-dimensional ultrasonic motion analysis system was used to measure the lumbopelvic rotation angle and lumbopelvic rotation movement onset. An independent t-test was used to determine between-group differences for each outcome measure (lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL-ITB length, and pain intensity). Results: The results showed that ADIM training plus TFL-ITB self-stretching decreased the lumbopelvic rotation angle, delayed the lumbopelvic rotation movement onset, and elongated the TFL-ITB significantly more than did ADIM training alone. Pain intensity was lower in the ADIM training plus TFL-ITB self-stretching group than the ADIM training alone group; however, the difference was not significant. Conclusion: ADIM training plus TFL-ITB self-stretching performed for a 2-week period at home may be an effective treatment for modifying lumbopelvic motion and reducing LBP.
        4,000원
        17.
        2024.04 구독 인증기관·개인회원 무료
        Five insecticides (Acrinathrin, Dinotefuran, Emamectin benzoate, Chlorfenapyr and fluxametamide) approved for tomato cultivation were evaluated in Frankliniella occidentalis populations collected from Chungcheong province (Cheongyang, Chungju and Gongju). Leaf dip bioassay was used to evaluate resistance levels (LC50). Bioassays on Acrinathrin demonstrated higher LC50 concentration in evaluated populations. In particular, the Chungju population was 745.61 times the recommended concentration of the insecticide. Other remarkable resistance levels were recorded for the Dinotefuran with 435.06 times and 196.29 times the recommended concentrations for the populations from Chungju and Gongju, respectively. Bioassays for Emamectin benzoate, Chlorfenapyr and Fluxametamide showed low resistance to insecticides in the evaluated populations.
        18.
        2024.04 구독 인증기관·개인회원 무료
        Yellow flower thrips (WFT), Frankliniella occidentalis is mainly controlled using chemical control methods. But the continuous use of chemical pesticides in greenhouse may contribute to development of insecticide resistance. Therefore, in this study, we evaluated the insecticidal activity of eleven insecticides against the WFT occurring in greenhouse pepper cultivation in the Gyeonggi province. The results showed no resistance in treatments with emamectin benzoate, fluxametamide, and flometoquin while high levels of resistance were recorded in treatments with acrinathrin, acetamiprid, and dinotefuran. The Anseong and Yeoju population was more resistant against spinetoram and chlorfluazuron, respectively, than populations from other regions.
        19.
        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
        20.
        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
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