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        검색결과 547

        61.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of light intensity and external sucrose on the vase life of cut roses were estimated by monitoring the net photosynthesis and chlorophyll fluorescence. Cut flowers were held under different light intensities 10 (L10) or 50 (L50) μmol‧m-2‧s-1 with or without treatment with external sucrose. We found substantial differences in stomatal conductance, photosynthesis rate, photosystem II (PSII) quantum efficiencies, specific fluxes, and vase life of the cut flowers when exposed to different light intensities. Light intensity at 50 μmol‧m-2‧s-1 increased photosynthesis capacity, thus delaying petal senescence and extending the vase life of cut flowers. L50 flowers maintained a high photosynthetic rate by reducing heat dissipation (DI0/RC) and increasing electron transport (ET0/TR0 and ET0/ABS) in the electron transport chain of the photosynthesis apparatus. The application of external sucrose extended the vase life of cut flowers by improving water balance and sustaining turgor pressure in the petals of the cut flowers. The net rate of photosynthesis of the cut flowers was increased by higher light intensity; however, it was not affected by the application of external sucrose. Our results indicate that the application of external sucrose is necessary to improve the longevity of cut flowers when endogenous sucrose production by photosynthesis is insufficient under low light conditions during the postharvest period. In addition, our results revealed that most of the photosynthetic parameters were significantly correlated with the vase life of cut rose flowers. Moreover, the relation between the rate of photosynthesis and chlorophyll fluorescence parameters indicates that the rise from the basic dark-adapted fluorescence yield to the maximum (OJIP transient) method can be used as a tool for the evaluation and prediction of the photosynthesis rate in cut flowers.
        4,500원
        62.
        2023.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        As the Biden administration succeeded President Trump’s chaotic and undisciplined trade and investment policies toward China, the last six months of 2022 have seen significant developments in the US trade law and economic policy toward China. These legislative and regulatory developments bring into sharper focus a broader and more aggressive US legal and regulatory structure fostering industrial policy and confronting China. The recent midterm elections in the US and meeting in Bali between Xi and Biden only seem to maintain the current unsettling state of affairs. The subsequent WTO panel decision against the United States concerning its Section 232 national security tariffs and its rejection of national security defense only further complicates the US-China trade relations. The legislative and regulatory measures emanating from the US in the last half of 2022 are not helpful and represent a worrisome development. These measures are by far more aggressive, with significant domestic and global implications. They portend a new emerging post-WTO order.
        4,600원
        63.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The research on dye-sensitized solar cells (DSSCs) is in the advanced stage today. The only concern observed so far has been regarding its stability and efficiency. Its power conversion efficiency can be increased by incorporating various methods and materials based on nanotechnology. Several attempts have been employed to develop advanced methods for eco-friendly, commercially viable, and sustainable DSSCs to minimize the energy crisis in the future. Photoanode is one of the essential components of DSSCs that can be modified using different nanostructures to enhance its efficiency. The TiO2 nanoparticlebased photoanode with gold and silver has proven to be potent materials for getting efficient DSSCs. The plasmonic and quantum confinement effects also play a vital role in efficiency enhancement. In this review, we discuss numerous attempts made by researchers in the last decade to modify the photoanode and their progress. We also look at different types of nanostructures, such as quantum dots, metal oxide doping, layered structures, nanocomposites, and thin film formation, that improve the efficiency of DSSCs. Several methods were reviewed to modify photoanodes to optimize electron transportation, light scattering, trapping power, surface area, and reduce charge recombination. The trend in the efficiency enhancement of DSSCs using TiO2, Au, ZnO, Ag, and graphene nanostructures-based photoanodes have been explored in great detail.
        6,100원
        64.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Benzene, toluene, ethylbenzene, and xylenes are commonly known as (BTEX) and include volatile organic compounds (VOCs) in ambient air. Exposure to some BTEX has been associated with health risks. This study aimed to reduce BTEX on the environment and human health dramatically. This research targeted decreasing the BTEX in an air environment by producing high surface area activated carbon (KA-AC) under optimized synthesis conditions from Ricinus communis as lignocellulosic waste using ZnCl2 solution, respectively. The influence of several activation parameters was investigated on the surface area, such as impregnation ratio, carbonization time, and carbonization temperature. The KA5-AC prepared under optimized conditions showed BET surface area and total pore volume of 1225 m2/ g, and 0.72 cm3/ g, respectively. The optimized synthesis conditions were as follows: 0.1, 0.5, 1, 2, and 5 M impregnation ratio, 450–950 °C carbonization temperature, and 100 min carbonization time. The characteristics of the optimized KA-AC were analyzed using nitrogen adsorption–desorption isotherm, scanning electron microscopy, and pore structural analysis. The results confirmed that the VOCs adsorption on KA-AC followed a monolayer adsorption isotherm over a homogeneous adsorbent surface. It showed the removal efficiency of benzene, toluene, ethylbenzene, and m, p-xylene (R2 = from 0.991 to 0.997). Moreover, the KA-AC exhibited good performance without considerable loss of efficacy throughout the experiments. Accordingly, it is concluded that developing low-cost activated carbon to use BTEX vapor adsorption research could be practical and developments to overcome for utilization in air pollution control.
        4,000원
        66.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        예이츠는 ‘우리는 마지막 낭만주의자다’라고 선언하면서 자신의 낭만적 세계관과 시적 패턴에 대해 명백히 한다. 그는 사랑, 좌절, 민족주의에 대한 세속적 감각과 열정을 드러내기 위해 자신의 초현실적이고 개인적인 본성과 주관성을 시에 가감없이 드러낸다. 워즈워스의 전통이 자연에서 범신론과 자연의 경이로움과 정신, 초자연적 요소 및 아찔한 아름다움을 찾아내는 것에 반해, 예이츠의 낭만주의는 의식적인 아니마 문디의 존재, 문화적 통합과 존재의 통일성에서 위안을 구한다. 아일랜드와 신화적 상상력을 찬양함으로써, 예이츠는 최대한으로 “사유를 두들겨 무엇인가를 만들어”내고, 현대시뿐만 아니라 아일랜드 문학 전통과 역사에 대한 독특한 문학 및 시적 전통을 생성한다. 예이츠는 사실주의와 비교와 역사에서 파생된 상상력, 환상과 신비주의의 유형, 갈등하는 자아와 민족주의와 종교를 엮어서 동반 상승효과를 만들어낸다.
        4,000원
        67.
        2022.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Contemporary environmental issues require the joint actions of the global community, which may assume many forms but always depend on developed and harmonized national legislations. States develop environmental law by implementing provisions of multilateral environmental agreements into national legislation. However, the implementation process sometimes prevents the effective adaptation of international legal norms. While the structure and mechanism of the implementation process have been frequently discussed from the relationship between international and municipal law, few studies have been dedicated to the implementation process of international environmental norms. Consequently, this study will analyze the implementation of multilateral environmental agreements with special references to the Republic of Kazakhstan. The article will present cases of implementation and the resulting issues in the national environmental legislation of the Republic of Kazakhstan. Moreover, it will examine national measures to solve these issues that will be relevant for all countries with similar ecological questions.
        4,900원
        75.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High-temperature friction performances of graphite blocks (GBs) and zinc phosphate impregnated graphite blocks (IGBs) were evaluated under various friction temperatures. The surface of IGB exhibited extremely lower average friction coefficient values, that was 0.007 at 400 °C and 0.008 at 450 °C, in comparison to that of GB (0.13 at 400 °C and 0.16 at 450 °C, respectively). The worn surface of IGB in the high-temperature friction test was smoother and more complete than that of GB. The wear under high temperature and load caused the transformation of zinc pyrophosphate to zinc metaphosphate and the formation of a continuous large-area boundary lubrication layer combined with graphite and metallic element on the wear surface. The superior tribology property of IGB could be attributed to the digestion of iron oxides by tribo-chemical reactions and passivation of the exposed dangling covalent bonds. Specifically, the layered structure generated on the IGB wear interface effectively decreased the adhesive forces and prevented the surface from serious damage.
        4,300원
        76.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study assessed the changes in the fiber properties of virgin and recovered fibers from lab-scale and pilot-scale depolymerization reactors based on the thermal air oxidation-resistance characteristics. Lab-scale and pilot-scale depolymerization reactors had different depolymerization volumes. Results showed that the lab-scale and pilot-scale peak solvent temperatures were 185 °C and 151 °C, respectively. The lab-scale had highest solvent temperature rate increase because of the small depolymerization volume and the dominant role of the cavitation volume. The structural properties of the recovered and virgin fibers were intact even after the depolymerization and after the pretreatment and oxidation-resistance test. We observed 1.213%, 1.027% and 0.842% weight loss for the recovered (lab-scale), the recovered (pilot-scale) and virgin fibers because of the removal of impurities from the surface and chemisorbed gases. Further, we observed 0.8% mass loss of the recovered fibers (lab-scale) after the oxidative-onset temperature because of the “cavitation erosion effect” from the dominant of the cavitation bubbles. The “cavitation erosion effect” was subdued because of the increased depolymerization volume in the pilot-scale reactor. Therefore, negligible impact of the pilot-scale mechanochemical recycling process on the structure and surface characteristics of the fibers and the possibility of reusing the recovered fibers recycling process were characteristic. Representative functional groups were affected by the thermal oxidation process. We conducted HPLC, HT-XRD, TGA– DSC, XPS, SEM, and AFM analysis and provided an extensive discussion of the test thereof. This study highlighted how misleading and insufficient small-lab-scale results could be in developing viable CFRP depolymerization process.
        4,800원
        77.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The serendipitous uncovering of carbon dot (CQDs) as budding candidate of carbonaceous nanomaterial has become now one of the hot topics in the research of material science and technology. The unique features of CQDs such as photo-physical properties, excellent biocompatibility, ease of synthesis, good aqueous dispersity, high chemical stability, and accessible functional groups for further modification make them one of the promising competitors in biological, photonic and energyrelated applications. Although some review articles on CQDs have been published, they typically cover all areas of CQDs applications, and no particular evaluation on the advancement of doped CQDs (D-CQDs) has been reported so far. In this review, we demonstrated characteristic features of D-CQDs focusing on doping strategies, discussion on recently adopted various synthesis processes, its applications and its qualitative comparison with each other. The recently developed concept on understanding the structure and optical properties of D-CQDs are also briefly described followed by their application on various fields primarily concentrated on bio-imaging and sensing applications. We also speculate its use in a variety of intriguing fields and its perspectives in near future.
        6,300원
        78.
        2022.05 구독 인증기관·개인회원 무료
        In thermal cutting process, gas flow injected from the nozzle has a significant effect on the cutting materials. The gas flow is difficult to observe gases are transparent, therefore, in this study, Schlieren method was adopted to visualize the gas flow inside the kerf. The kerf shape was inserted between two slices of transparent glass in order to imitate the real cutting environment. In order to get the flow characteristics, a high speed camera was equipped and the image processing was applied to compare the before and after injection images. As a result, the method for visualizing gas flow was successfully developed and also expected to be applied to the analysis of purging gas in various welding environments.
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