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        검색결과 3,983

        193.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study investigated the field applicability of pervious concrete to pavement base courses. Pervious concrete was developed at laboratory level, and the compaction methods, field moisture content, and fundamental properties when the material was constructed in the field were studied. METHODS : Field-applied pervious concrete was compacted at different levels using a tandem roller, and cores were taken to investigate the compressive strength, infiltration rate, continued porosity, and freeze-thaw resistance. In addition, the optimum field construction and quality control of the moisture content of a batch plant were measured. RESULTS : The moisture content of pervious concrete has an essential effect on workability and quality control during field test construction. From the test herein, the optimum value at a batch plant was found to be approximately 2.5±0.1%. The compaction level is also a crucial parameter at construction sites because it affects the mechanical and penetration properties. Considering both compressive strength and drainage, the recommended compaction was three times the round trip when a tandem roller was used. The penetration coefficient was 0.88 cm/sec when applying three times the round trip of the tandem roller. The freezing and thawing weight loss rates of the applied pervious concrete satisfied the required condition of 14% or less, regardless the compaction level. CONCLUSIONS : With the suggested mixed proportions of pervious concrete, the recommended compaction was three times the round trip of a tandem roller and a moisture content of approximately 2.5±0.1% from a batch plant. When these conditions were satisfied, the mechanical and drainage properties satisfied the required criteria.
        4,000원
        194.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Smart devices including smart phones have many benefits. However, prolonged used may aggravate cervical pain and postural deformity. Smart devices with appropriate applications (apps) may be useful cost-effective and easy-to-use instruments to relieve cervical pain and improve range of motion (ROM). Objectives: To review recent experimental studies on smart device-based apps on cervical pain and postural ROM improvement. Design: Systemic review study. Methods: Ten articles were selected through bibliographic searches and successive and exclusion procedure of the PubMed, ScienceDirect, and Google Scholar. Out of initial 1,046 articles, 98 articles were selected from abstract review. 33 articles were selected for full article review. Final 10 research articles were selected. Results: Three static ROM feasibility, two active ROM feasibility, four self-management promotion, and one pre/post research study articles were included. Smart device with artificial intelligent (AI) based app were utilized promote adherence to physical activity. Conclusion: Smart device apps steadily showed high feasibility even for research purpose. Studies on AL and machine learning apps showed mixed results for need for wider and precision application.
        4,000원
        195.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, hollow carbon spheres (HCS) have aroused great interests in the field of energy storage and conversion owing to their unique morphology, structure and other charming properties. Nevertheless, unsatisfactory electrical conductivity and relatively poor volumetric energy density caused by inevitable gaps between discrete carbon spheres greatly impede the practical application of HCS. In this work, for the first time we propose a novel dual-template strategy and successfully fabricate interconnected 3D hollow N-doped carbon network (HNCN) by a facile and scalable pyrolysis process. By systematical characterization and analysis, it can be found that HNCN is assembled by HCS and lots of mesoporous carbon. Compared to the counterparts, the obtained HNCN exhibits unique 3D interconnected architecture, larger specific surface area, hierarchical meso/macropore structure, higher structure defects, higher N doping amount and more optimized N configurations (especially for pyridinic-N and graphitic-N). As a result, these advantageous features endow HNCN with remarkably promoted electrochemical performance for supercapacitor and oxygen reduction reaction. Clearly, our proposed dual-template strategy provides a good guidance on overcoming the intrinsic shortcomings of HCS, which undoubtedly broadens their application in energy storage and conversion.
        4,000원
        196.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Owing to their simplicity and ease of synthesis, carbon nanotubes (CNTs) have captivated attention of researchers. Many engineering applications have investigated the new features of nanostructured carbon nanotubes, such as large surface area, stiffness and durability. CNTs have opened up new opportunities for environmental improvement, pollution management and application in a variety of fields. Multiple types of pollution are produced as a result of population growth, urbanization and industrialization. CNTs are used to solve a variety of challenges, including environmental difficulties, water pollution, biomedical applications, and so on. It becomes an unavoidable present and future material. Different applications of CNTs have been presented in this review paper. CNTs are potential material having number of uses, including water purification, drug delivery, preservatives, catalysis, genetic engineering and artificial implants which are reviewed in this review article. This paper is presenting an explicit and systematic progress of CNTs for water treatment, medicinal uses drug delivery, artificial implants and so on, and a multitude of CNT applications in broad disciplines and their purification methods have been covered. The issues related to synthesis technologies, purification technology, bio-medicinal application and catalytic property of CNTs within the framework of different engineering applications and environmental impact are discussed in this study.
        7,800원
        197.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study compares the abundance and community structure of zooplankton organisms from pelagic regions, and considers particularly the trophic levels vs. zooplankton abundances and biomass. Zooplankton samples were collected three times from May to November 2022, at 30 temperate lakes and reservoirs, which belong to four different river basins. The total zooplankton abundance, biomass and species index were showed considerable spatial variation. The spatial pattern of rotifer abundance was similar to that of total zooplankton abundance, while there were not showed similar patterns of zooplankton biomass (μg L-1) in lentic ecosystems. The rotifer strongly dominated the zooplankton assemblage in smaller lentic system than that of larger. A total of 130 species of zooplankton were identified (83 rotifers, 34 cladocerans and 13 copepods). The total average of zooplankton abundance and biomass were 213.7±342.3 Ind. L-1 (n=129) and 1382.8±1850.4 μg L-1, respectively. Total and average of zooplankton abundance were usually dominated by the rotifers (>56.9%), while those of zooplankton biomass were dominated by the cladocerans and copepods (>73.6%) in lentic ecosystems. Considering the Trophic State Index (TSI), the factors of zooplankton abundance and biomass were included in between meso- and eutrophic states (27 lakes, 90% of all). The mean abundance and biomass of zooplankton in eutrophic systems were higher than that of meso- and hypertrophic systems. From this result, we suggest that management strategy for the lentic ecosystem water environment has to be focused more on small-sized lakes and reservoirs, in terms of zooplankton assemblages.
        4,200원
        198.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, Korean government has introduced Multi Metric Indices (MMI) using various biocommunity information for aquatic ecosystem monitoring and ecosystem health assessment at the national level. MMI is a key tool in national ecosystem health assessment programs. The MMI consists of indices that respond to different target environmental factors, including environmental disturbance (e.g. nutrients, hydrological and hydraulic situation of site etc.). We used zooplankton community information collected from Korean lakes to estimate the availability of candidate zooplankton MMI indices that can be used to assess lake ecosystem health. First, we modified the candidate indices proposed by the U.S. EPA to suit Korean conditions. The modified indices were subjected to individual index suitability analysis, correlation analysis with environmental variables, and redundancy analysis among indices, and 19 indices were finally selected. Taxonomic diversity was suggested to be an important indicator for all three taxonomic groups (cladoceran, copepod, rotifer), on the other hand, the indices using biomass for large cladocerans and copepods, while the indices using abundance were suggested for small cladocerans and rotifers.
        4,500원
        199.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Forest destruction is an inevitable result of the development processes. According to the environmental impact assessment, over 10% of the destroyed trees need to be recycled and transplanted to minimize the impact of forest destruction. However, the rate of successful transplantation is low, leading to a high rate of tree death. This is attributable to a lack of consideration for environmental factors when choosing a temporary site for transplantation and inadequate management. To monitor transplanted trees, a field survey is essential; however, the spatio-temporal aspect is limited. This study evaluated the applicability of remote sensing for the effective monitoring of transplanted trees. Vegetation indices based on satellite remote sensing were derived to detect time-series changes in the status of the transplanted trees at three temporary transplantation sites. The mortality rate and vitality of transplanted trees before and after the transplant have a similar tendency to the changes in the vegetation indicators. The findings of this study showed that vegetation indices increased after transplantation of trees and decreased as the death rate increased and vitality decreased over time. This study presents a method for assessing newly transplanted trees using satellite images. The approach of utilizing satellite photos and the vegetation index is expected to detect changes in trees that have been transplanted across the country and help to manage tree transplantation for the environmental impact assessment.
        4,500원