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        검색결과 9,512

        2550.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        선박의 안전과 보안의 유지는 공급망의 각 단계에서 화물운송 및 여객의 인명 안전을 보장하는데 중추적인 역할을 한다. ISPS Code는 선원과 선박을 보안 위협으로부터 보호하기 위해 SOLAS 협약에 채택되었고, STCW 2010 마닐라 개정에 따라 선원은 반드시 보안교육을 이수해야 한다. 효과적인 선원의 교육과 훈련은 선박의 보안 관련한 위험을 최소화하기 위한 적절한 이행활동의 수준을 보장하는데 중요하다. 이 연구의 목적은 선원들이 이수한 보안교육과 선원의 보안인식 및 선박의 보안성과 사이의 관계를 실증 분석하는데 있다. 연구 결과에 따르면 (1) 선박 보안 교육을 이수한 선원들은 선박 보안에 대한 인식이 높고 (2) 이러한 보안 교육 및 보안 인식은 선박의 보안성과에 긍정적 영향을 미치며, (3) 보안 인식은 보안 교육과 보안성과 관계에서 매개 효과가 있는 것으로 분석되었다. 따라서 보안 교육과 훈련은 선원의 보안인식과 보안성과에 중요한 영향을 미치며, 이는 결과적으로 해운산업에서 보다 경제적․운영적 및 이미지 측면에서 주요 이점으로 해석될 수 있을 것이다.
        4,200원
        2551.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For electrodes in electrochemical double-layer capacitors, carbon nanofibers (CNFs) were prepared by thermal treatment of precursor polymer nanofibers, fabricated by electrospinning. Poly(acrylonitrile-co-vinylimidazole) (PAV) was employed as a precursor polymer of carbon nanofibers due to the effective cyclization of PAV polymer chains during thermal treatment compared to a typical precursor, polyacrylonitrile (PAN). PAV solutions with different comonomer compositions were prepared and electrospun to produce precursor nanofibers. Surface images obtained from scanning electron microscopy showed that their nanofibrous structure was well preserved after carbonization. It was also confirmed that electrospun PAV nanofibers were successfully converted to carbon nanofibers after the carbonization step by Raman spectroscopy. Carbon nanofiber electrodes derived from PAV showed higher specific capacitances and energy/power densities than those from PAN, which was tested by coin-type cells. It was also shown that PAV with an acrylonitrile/vinylimidazole composition of 83:17 is most promising for the carbon nanofiber precursor exhibiting a specific capacitance of 114 F/g. Their energy and power density are 70.1 Wh/kg at 1 A/g and 9.5 W/kg at 6 A/g, respectively. In addition, pouch cells were assembled to load the higher amount of electrode materials in the cells, and a box-like cyclic voltammetry was obtained with high capacitances.
        4,000원
        2552.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Chlorella-derived activated carbon (CDAC) with a high specific surface area and hierarchical pore structure was prepared as a CO2 adsorbent and as a supercapacitor electrode material. During KOH activation of Chlorella-derived carbon, metallic K gas penetrated from the outer walls to the inner cells, and pores formed on the outer frame and the inner surface. Micropores were dominant in CDAC, contributing toward a high specific surface area (> 3500 m2/g) and a hierarchical pore structure owing to the cell walls. Consequently, CDAC exhibited a high CO2 adsorption capacity (13.41 mmol/g at 10 atm and room temperature) and afforded high specific capacitance (142 F/g) and rate capability (retention ratio: 91.5%) in supercapacitors. Compared with woody- and herbaceous-biomass-derived activated carbons, CDAC has a superior specific surface area when the precursors are used without any pretreatment under the same conditions due to their soft components such as lipids and proteins. Furthermore, developing microalgae into high-value-added products is beneficial from both economic and environmental perspectives.
        4,000원
        2553.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Eurytoma maslovskii conduces the unexpected plum dropping. It stayed overwinter inside the pits of the dropped plums and able to oviposit on plum surface when the diameter of the plums are over 16 mm prior to endocarp hardening. To control this harmful pests is too much essential to plum orchard. Therefore, the plum seed crusher (PSC) was designed and developed according to the purpose of perishing the pests through destroying the dropped plums. The rocks and the weeds were removed from the plum orchard prior to the test. Manually operated plum seed crusher picked-up the dropped plums from the ground and crushed them. The performance of PSC was evaluated by applying 2.5 and 3.0 km/h travelling speeds, and controlling the gaps; 18, and 28 mm intervals between plum pick-up discs. The test result showed the plum pick-up rate was 98±2.0%, and 92±5.3% with the machine travelling speed of 3.0 km/h in laboratory. Further, it changed to 95±8.7%, and 93±5.8% when the travelling speed was used 2.5 km/h. In both cases of test plum pick-up discs were maintained 18 mm, and 28 mm gap intervals, respectively. Furthermore, in field conditions, pursuing to similar gap intervals, the plum pick-up rate was 94±4.0%, and 92±2.0% with the speed of 3.0 km/h albeit it showed 92±4.0%, and 90±3.5% when the speed was decreased to 2.5 km/h. The maximum plum pick-up rate was found at 18 mm disc intervals with 3.0 km/h travelling speeds. The crushing teeth were selected 8 mm in height by repeated test to destroy the plum seeds. The result showed 100% crushing efficiency was facilitated to entire tests at 280 RPM crushing speeds regardless of plum sizes and shapes. This machine is preferred for the farmers to control the damage of plums by preventing the propagation of the identified pests.
        4,000원
        2554.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lignocellulosic materials such as agricultural residues have been identified as potential sustainable sources that can replace petroleum-based polymers. This study focused on the conversion of lignin extracted from bagasse to carbon fiber (CF) and cellulose nanocrystal (CNC). The highest extraction of lignin yield was achieved at 100 °C using 10% NaOH for 12 h. Carbon fibers were obtained by electro-spinning of bagasse lignin blended with polyvinyl alcohol (PVA) (11 wt/v %) followed by thermo-stabilization (250 °C) in an oxidizing atmosphere and further carbonization in an inert atmosphere (850 °C). Conventional hydrolysis process was used to extract cellulose nanocrystal from bagasse pulp. Morphological (scanning electron microscopy, SEM), spectral (Fourier transform infrared, FTIR) spectroscopy, elemental analysis, thermal characterization and surface area measurements have been carried out. Figures originated by SEM showed that CF ranges from 145 to 204 nm, while stabilized bagasse cellulose nanocrystal (SCNC) appeared as rod-shape like structure in the range of length 600–800 nm and diameter 5.33–19 μm. Characterization results revealed that CF exhibits microporous structure, while bagasse lignin and SCNC display mesoporous structure. In addition, the results proved that SCNC exhibits a percentage removal 71.56% for methylene blue dye in an aqueous solution.
        4,000원
        2555.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aims to explore the diverse characteristics of obese groups of Korean males in their 20’s to 40’s. A total of 201 males who each had a BMI (Body Mass Index) of 23 or over were recruited through a convenient sampling. Samples were categorized into groups of overweight, slightly obese, and severely obese, and submitted for data analysis. Results are summarized as follows. First, in terms of demographic characteristics, slightly and severely obese males were older than overweight males. There were also group differences in marital status and household income. Second, slightly and severely obese groups demonstrated a higher perception of obesity and a lower perception of health than did the overweight group. Third, there were no group differences in body satisfaction, socio-cultural attitudes toward appearance, and self-esteem. Based on these results, we concluded that overweight, slightly obese, and severely obese groups were distinguishable from each other in terms of their demographic characteristics, whereas the slightly obese group and the severely obese group were not different in terms of perception of obesity, perception of health, weight control behaviors, body satisfaction, body image, socio-cultural attitudes toward appearance, and self-esteem. These findings may reflect that people may not become increasingly sensitive to socio-psychological stimulations as they gain more weight if they have exceeded a certain level of obesity. This observation provides meaningful implications for the differences among obesity groups given the lack of prior research focusing on this issue.
        5,100원