검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 3,068

        1881.
        2007.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The basic building block of solar filaments/prominences is thin threads of cool plasma. We have studied the spectral properties of velocity threads, clusters of thinner density threads moving together, by analyzing a sequence of Hα images of a quiescent filament. The images were taken at Big Bear Solar Observatory with the Lyot filter being successively tuned to wavelengths of -0.6, -0.3, 0.0, +0.3, and +0.6 Åfrom the centerline. The spectra of contrast constructed from the image data at each spatial point were analyzed using cloud models with a single velocity component, or three velocity components. As a result, we have identified a couple of velocity threads that are characterized by a narrow Doppler width (ΔλDÅ=0.27), a moderate value of optical thickness at the Hα absorption peak(T0=0.3) and a spatial width(FWHM) of about 1". It has also been inferred that there exist 4-6 velocity threads along the line of sight at each spatial resolution element inside the filament. In about half of the threads, matter moves fast with a line-of-sight speed of 15±3 km s-1, but in the other half it is either at rest or slowly moving with a line-of-sight velocity of 0±3 km s-1. It is found that a statistical balance approximately holds between the numbers of blue-shifted threads and red-shifted threads, and any imbalance between the two numbers is responsible for the non-zero line-of-sight velocity determined using a single-component model fit. Our results support the existence not only of high speed counter-streaming flows, but also of a significant amount of cool matter either being at rest or moving slowly inside the filament.
        4,900원
        1882.
        2007.07 구독 인증기관 무료, 개인회원 유료
        지적재산권의 anticommons3) 문제는 악명이 높다. 하나의 물건 또는 서비스에 다수의 지적재산권이 존재하는 경우에 장래 그 분야 사업에 진출하려는 기업이 주저하거나 부차적인 비용을 들거나 홀드 업(held up) 문제를 발생시킬 것을 염려하는 사람들도 많다. 이 논문은 현재의 법령 내에서 사적질 서형성(private ordering)에 기초한 해결방안을 제안하고 있다. 이러한 접근 방식은 유한책임회사를 설립하고, 지적재산권자들이 사업을 영위하는데 실질적인 이해관계를 갖고서 이러한 기업에 참여하도록 하는 인센티브를 제공하는 것이다. 그러나, 현재 지적재산권자들은 홀드아웃(hold out)4)과 같은 기회주의적으로 상황에 따라 이익만을 추구하는 행동을 하지 않도록 하는 사회적인 압력도 받고있다. 지적재산권자에 대한 보상과 자기 규제(self restraint)를 적절히 행하여 관련된 지적재산권자들에 대한 행동을 조정하는 것이 이 논문에서 제안된 구조이다. 제시된 접근방식은 변호사들이 거래비용 엔지니어(transaction cost engineer)로서의 역할을 하여 문제를 처리할 수 있도록 설계되었다.
        6,100원
        1883.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A series of activated carbons (ACs) were derived from sugarcane bagasse under two activation schemes: steam-pyrolysis at 600-800℃ and chemical activation with H3PO4 at 500℃. Some carbons were treated at 400, 600℃, or for 1-3 h, and/or in flowing air during pyrolysis of acid-impregnated mass. XRD profiles displayed two broad diffuse bands centered around 2θ=23 and 43˚, currently associated with diffraction from the 002 and 100/101 set of planes in graphite, respectively. These correspond to the interlayer spacing, Lc, and microcrystallite lateral dimensions, La, of the turbostratic (fully disordered) graphene layers. Steam pyrolysis-activated carbons exhibit only the two mentioned broad bands with enhancement in number of layers, with temperature, and small decrease in microcrystallite diameter, La. XRD patterns of H3PO4-ACs display more developed and separated peaks in the early region with maxima at 2θ=23, 26 and 29˚, possibly ascribed to fragmented microcrystallites (or partially organized structures). Diffraction within the 2θ=43˚ is still broad although depressed and diffuse, suggesting that the intragraphitic layers are less developed. Varying the conditions of chemical activation inflicts insignificant structural alterations. Circulating air during pyrolysis leads to enhancement of the basic graphitic structure with destruction and degradation in the lateral dimensions.
        4,000원
        1886.
        2007.04 KCI 등재 구독 인증기관·개인회원 무료
        Oral squamous cel1 carcinoma(OSCC) is the most common malignancy of head neck region. Typically OSCC cells s how persist ent invasion that frequently leads to local recurrence and distant lymphatic metastasls However, molecular mechanisms of invasion of OSCC remain poorly understood. Her e we identifi ed periostin, interferon induced transmembrane protein l (IF1TM1) and wingless-type MMTV integration site family, member 5B(WNT5B) , as invasion promoting molecules in OSCC by comparing gene expression profiles between a parent OSCC cell line(MSCC-l) and its highly invasive clone(MSCC-1nvl). Overexpression of periostin, IFITMl and WNT5B mRNAs were confirmed in MSCC-1nvl by RT-PCR. Transfection of these molecules promoted invasion of OSCC cells Moreover , siRNA t r eatment of these molecules suppressed invasion of cancer cells in vitro I nter estingly, Periostin, 1F1TMl and WNT5B were highly expressed in OSCCs in comparison with nonnal tissues. 1n an orthotopic mouse model of OSCC, periostin-overexpressing cells metas tasized spontaneously to cervical lymph nodes and t o t he lung through their aggressive invasiveness. These findings suggest that peri ostin, IFITMl and WNT5B play important roles for invasion and of OSCC and can be prognostic markers and therapeutic t argets of OSCC.