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        검색결과 45

        21.
        2010.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Hybridization of semiconductor materials with carbon nanotubes (CNTs) is a recent field of interest in which new nanodevice fabrication and applications are expected. In this work, nanowire type GaAs structures are synthesized on porous single-wall carbon nanotubes (SWCNTs) as templates using the molecular beam epitaxy (MBE) technique. The field emission properties of the as-synthesized products were investigated to suggest their potential applications as cold electron sources, as well. The SWCNT template was synthesized by the arc-discharge method. SWCNT samples were heat-treated at 400˚C under an N2/O2 atmosphere to remove amorphous carbon. After heat treatment, GaAs was grown on the SWCNT template. The growth conditions of the GaAs in the MBE system were set by changing the growth temperatures from 400˚C to 600˚C. The morphology of the GaAs synthesized on the SWCNTs strongly depends on the substrate temperature. Namely, nano-crystalline beads of GaAs are formed on the CNTs under 500˚C, while nanowire structures begin to form on the beads above 600˚C. The crystal qualities of GaAs and SWCNT were examined by X-ray diffraction and Raman spectra. The field emission properties of the synthesized GaAs nanowires were also investigated and a low turn-on field of 2.0 V/μm was achieved. But, the turn-on field was increased in the second and third measurements. It is thought that arsenic atoms were evaporated during the measurement of the field emission.
        4,000원
        22.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The field emitters were fabricated by screen-printing of carbon nanotube paste, and their emission stabilities were evaluated. It was found that the emission stability measured in a sealed device is much higher than that measured in a vacuum chamber in spite of similar pressure. This was because oxygen gas was scarcely remained in the sealed device, while the gas is continuously supplied into the vacuum chamber during the stability measurement. It was found that the plasma treatment etched the protruded CNTs, resulting in the uniform height of CNT tips. As a result, the stability was increased remarkably. It was also found that the stability of CNT paste emitter was improved by electrical aging and that the optimum condition for the aging was varied with the size of emitter.
        4,000원
        23.
        2008.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver (Ag) powders as a bonding material between the CNTs and cathode electrodes. The effects of the powder size on the sintering behavior, the current density and emission image for CNT cathodes were investigated. As the diameter of the Ag powders decreases to 10 nm, the sintering temperature of the CNT cathode was lowered primarily due to the higher specific surface area of the Ag powders. In this study, it was demonstrated that nano-sized Ag powders can be feasibly used as a bonding material for a screen-printed CNT cathode, yielding a high current density and a uniform emission image.
        4,000원
        26.
        2006.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Near-IR H2 emission features in the northern region of the Orion A giant molecular cloud were observed in the CO J = 1 → 0 line in search of CO outflows. Out of the 30 sources surveyed, CO line wings were detected toward 28 positions, suggesting a strong correlation between H2 jets and CO outflows. Blueshifted wings were detected toward 26 positions while redshifted wings were detected toward 15 positions, which suggests that there is a bias in the source selection. The bias is more severe in OMC 3 than in OMC 2. Since the protostars in OMC 3 are younger and more deeply embedded, the bias may be caused by the difference of extinction between blueshifted and redshifted outflows. Some physical parameters of the outflows were derived from the line profiles.
        4,000원
        34.
        2000.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, the carbon fibers-reinforced carbon matrix composites made with different carbon char yields of phenolic resin matrix have been characterized by mechanical flexural tests for acoustic emission properties. The composites had been fabricated in the form of two-dimensional polyacrylonitrile based carbon fibers during the carbonization process. It was found that the composites made with the carbon char yield-rich of resin matrix result in better mechanical interfacial properties, i.e., the interlaminar shear strength (ILSS) of the composites. The data obtained from the acoustic emission monitored appeared to show that the composites made with carbon char yield-rich were also more ductile. From the acoustic emission results, the primary composite failure was largely depended on the debonding at interfaces between fibers and matrix. The interlaminar shear strengths of the composites were correlated with the acoustic emission results.
        3,000원
        35.
        1994.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        bismaleimide취약성을 개선 하기 위하여 toughening agent인 TM120을 첨가하여 carbon/(± 45˚)2s를 제조하고 이들의 파손과 기계적 특성을 인당실험과 음향방출을 통해 자세히 논하였다. 첨가하는 TM120의 비율은 0, 5, 10, 15, 20, 25phr이었고, 1, 4-diazobicyclo-(2, 2, 2)-octane(DABCO) 0.2phr를 경화 촉진제로 사용하였다. 또한, 탄소 섬유는 Toray사의 T300를 사용하였고, 음향방출과 인장실험 결과로 TM120이 적당한 첨가량은 20phr이었으며, TM120은 cabon/(± 45˚)2s의 파손특성과 기계적물성에 많은 영향을 미쳤다.
        4,000원
        36.
        2023.11 서비스 종료(열람 제한)
        This article analyzes the structural characteristics and working principles of heat treatment equipment while considering the possibility of “zero-carbon manufacturing.” It integrates the concepts of material flow, energy flow, and waste recycling, and, by following the life cycle theory, constructs a system boundary model for heat treatment equipment to track the direction of carbon emissions throughout various stages. It identifies the sources and forms of carbon emissions in the entire process of heat treatment equipment and proposes carbon emission estimation models for each stage, upon which a comprehensive data inventory for heat treatment equipment is established.
        37.
        2020.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This research aims to examine (1) the effect of carbon emission disclosure on firm value, (2) the effect of good corporate governance on firm value, (3) the mediating role of financial performance between carbon emission disclosure and firm value, and (4) the mediating role of financial performance between good corporate governance and firm value. The research sample includes 43 mining, agro, and manufacturing firms listed in the Indonesian Stock Exchange over the 2015-2017 period. Carbon emission disclosure is measured by an indicator of the Global Reporting Initiative Series of Environmental Aspect. Good corporate governance is measured by the corporate governance score of shareholder rights, boards of directors, outside directors, audit committee and internal auditor, and disclosure to investors. Financial performance is measured by return on assets, while firm value is measured by Tobin’s Q. Data analysis uses the structural equation modeling. The result shows carbon emission disclosure and good corporate governance have no direct effect on firm value. On the other hand, financial performance mediates the effect of carbon emission disclosure and good corporate governance on firm value. It shows that higher carbon emission disclosure and good corporate governance are meaningless for the investor if they do not give any financial performance improvement.
        38.
        2019.08 서비스 종료(열람 제한)
        In the context of low-carbon economy, the assumption of free carbon emission is disappearing, and manufacturing enterprises need to plan their low-carbon strategies. Enterprises need to consider a series of issues such as investment in low-carbon technology, control and prevention of carbon emissions in the production process, and trading of carbon emission rights. These decisions and actions require accounting to reflect enterprises' carbon emission activities. This paper starts with the connotation of carbon emission cost, analyzes the confirmation process and classification of carbon emission cost, and obtains the combination point of optimal carbon emission and carbon emission cost by constructing the short-term carbon emission cost decision model. After further analysis of the long-term carbon emission cost decision model, it is proposed that the long-term carbon emission cost will decrease with the decrease of carbon emission. At the same time, the paper takes the automobile industry as an example to analyze the carbon tax levied on "carbon emission", and verifies the decision-making model of short-term and long-term carbon emission cost.
        39.
        2019.02 KCI 등재 서비스 종료(열람 제한)
        Purpose - The industrial structure upgrading can play an important role in promoting the carbon emission efficiency. Thus, this paper attempts to study the impact of industrial structure upgrading on carbon emission efficiency in order to reduce carbon emissions. Research design, data, and methodology - This paper selects panel data of 30 provinces and municipalities (autonomous regions) in China from 2001 to 2016, and divides them into three regions. The Moore index is used to measure the industrial structure upgrading, the non-radial SBM model based on undesired output is used to measure the slack variable to calculate the total factor carbon emission efficiency. Finally the impact of industrial structure upgrading on the carbon emission efficiency are analyzed. Results - It is found that the Moore index and the carbon emission efficiency in the eastern region is the highest in the three regions. Conclusions - The influence of various influencing factors on carbon emission efficiency is different between regions. The Moore index has a positive effect on the carbon emission efficiency in the eastern region, and has a negative influence coefficient on the central region. The effect on the western region is not obvious.
        40.
        2017.05 서비스 종료(열람 제한)
        국제연합식량농업기구(FAO, United Nations Food and Agriculture Organization)의 보고서에 따르면 21세기 전 세계의 인구는 2050년 약 90억에 달할 것으로 예측되며, 이러한 인구팽창으로 인한 식량부족 및 사료공급의 문제는 생산 시 야기되는 탄소, 질소의 손실로 인한 자원고갈 및 환경영향에 대한 우려와 함께 전 세계의 큰 관심사로 화두되었다. 또한, 대두, 유채, 팜을 이용한 식물성 바이오오일의 생산은 식량작물을 에너지작물로 활용함에 따라 개발도상국의 식량부족 문제를 심화시키는 악효과를 야기했다. 이렇듯 현대사회가 직면한 복합적인 문제점을 해결하기 위해 전 세계적으로 새로운 미래자원에 대한 탐색이 이루어졌으며, 곤충이 하나의 유망자원으로서 새롭게 각광받기 시작하였다. 다양한 곤충 중 흰개미의 경우, 분류계통상 고등 및 하등 흰개미로 분류되는데 종류에 따라 섭식대상이 다양하며 소화기작에서도 약간의 차이를 보인다. 특히 목질을 섭식하는 흰개미는 난분해성 물질인 리그닌과 셀룰로오스의 분해능력으로 인해 해외에서는 이미 오래전부터 흰개미의 장내 미생물을 이용하여 목질계 바이오매스로부터 바이오에탄올을 생산하는 방법에 대해 연구가 진행되어왔다. 하지만 국내에서는 흰개미를 목조 문화재를 가해하는 해충으로 분류하여 흰개미의 방제에 초점을 맞추어 연구가 많이 진행되어왔을 뿐 유용자원으로서의 흰개미의 잠재성에 대한 관심과 연구가 미흡한 실정이다. 또한, 흰개미는 우수한 단백질 공급원으로서 일부 국가에서는 식용 및 사료로서 활용을 하고 있지만 이에 따른 환경영향 및 효율에 관한 연구 역시 미흡하다. 따라서 본 연구는 국내에 분포하는 흰개미 중 일본흰개미(Reticulitermes speratus kyushuensis Morimoto)를 대상으로 흰개미가 주로 섭식하는 폐목재를 먹이로 주어 사육하였을 때, 생산되는 오일과 식용의 온실가스 발생량과 탄소와 질소의 순환효율을 정량화하여 흰개미를 산업용으로서 활용하는 것에 대한 타당성과 전체 탄소와 질소의 물질흐름에 있어서 환경적・경제적 이점을 정량화하고자 하였다.
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