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      • SCISCIESCOPUS

        Nonlinear wave interactions generate high-harmonic cyclotron emission from fusion-born protons during a KSTAR ELM crash

        Chapman, B.,Dendy, R.O.,Chapman, S.C.,McClements, K.G.,Yun, G.S.,Thatipamula, S.G.,Kim, M.H. International Atomic Energy Agency 2018 Nuclear fusion Vol.58 No.9

        <P>The radio frequency detection system on the KSTAR tokamak has exceptionally high spectral and temporal resolution. This enables measurement of previously undetected fast plasma phenomena in the ion cyclotron range of frequencies. Here we report and analyse a novel spectrally structured ion cyclotron emission (ICE) feature in the range 500 MHz to 900 MHz, which exhibits chirping on sub-microsecond timescales. Its spectral peaks correspond to harmonics <I>l</I> of the proton cyclotron frequency <I>f</I> <SUB>cp</SUB> at the outer midplane edge, where <I>l</I>  =  20–36. This frequency range exceeds estimates of the local lower hybrid frequency <I>f</I> <SUB>LH</SUB> in the KSTAR deuterium plasma. The new feature is time-shifted with respect to a brighter lower-frequency chirping ICE feature in the range 200 MHz (8<I>f</I> <SUB>cp</SUB>) to 500 MHz (20<I>f</I> <SUB>cp</SUB>), which is probably driven (Chapman <I>et al</I> 2017 <I>Nucl. Fusion</I> <B>57</B> 124004) by 3 MeV fusion-born protons undergoing collective relaxation by the magnetoacoustic cyclotron instability (MCI). Here we show that the new, fainter, higher-frequency chirping ICE feature is driven by nonlinear wave coupling between different neighbouring spectral peaks in the lower-frequency ICE feature. This follows from bispectral analysis of the measured KSTAR fields, and of the field amplitudes output from particle-in-cell (PIC) simulations of the KSTAR edge plasma containing fusion-born protons. This reinforces the identification of the MCI as the plasma physics process underlying proton harmonic ICE from KSTAR, while providing a novel instance of nonlinear wave coupling on very fast timescales.</P>

      • SCISCIESCOPUS

        Sub-microsecond temporal evolution of edge density during edge localized modes in KSTAR tokamak plasmas inferred from ion cyclotron emission

        Chapman, B.,Dendy, R.O.,McClements, K.G.,Chapman, S.C.,Yun, G.S.,Thatipamula, S.G.,Kim, M.H. International Atomic Energy Agency 2017 Nuclear fusion Vol.57 No.12

        <P>During edge localised mode (ELM) crashes in KSTAR deuterium plasmas, bursts of spectrally structured ion cyclotron emission (ICE) are detected. Usually the ICE spectrum chirps downwards during an ELM crash, on sub-microsecond timescales. For KSTAR ICE where the separation of spectral peak frequencies is close to the proton cyclotron frequency <img ALIGN='MIDDLE' ALT='$\Omega_{\rm cp}$ ' SRC='http://ej.iop.org/images/0029-5515/57/12/124004/nfaa8e09ieqn001.gif'/> at the outer plasma edge, we show that the driving population of energetic ions is likely to be a subset of the 3 MeV fusion protons, born centrally on deeply passing orbits which drift from the core to the edge plasma. We report first principles modelling of this scenario using a particle-in-cell code, which evolves the full orbit dynamics of large numbers of energetic protons, thermal deuterons, and electrons self-consistently with the electric and magnetic fields. The Fourier transform of the excited fields in the nonlinear saturated regime of the simulations is the theoretical counterpart to the measured ICE spectra. Multiple simulation runs for different, adjacent, values of the plasma density under KSTAR edge conditions enable us to infer the theoretical dependence of ICE spectral structure on the local electron number density. By matching this density dependence to the observed time-dependence of chirping ICE spectra in KSTAR, we obtain sub-microsecond time resolution of the evolving local electron number density during the ELM crash.</P>

      • Cave communities and the future

        Chapman, Phil The Speleological Society 1996 Journal of the speleological society of korea Vol.4 No.1

        Caves abd the life they contain face constant pressure from a worldw demand for cement. hydro-electric power and land for building a agriculture. The 8th International Congress of Speleology held in Kentu two years ago passed a resolution on behalf of the IUCN "Cave Speci Group" which called for "...biological surveys of threatened caves. mos in the tropics, and ecological studies to solve specific managem provlems on the causes of endangerment and how these can be remov or mitigated". This final article in the "Cave Life" series explains the n for an ecological approach to cavelife conservation.

      • SCOPUSKCI등재
      • SCALING HIGH PERFORMANCE CMOS INTO THE 21st CENTURY

        Chapman,Richard A. 대한전자공학회 1995 ICVC : International Conference on VLSI and CAD Vol.4 No.1

        The roadmap for CMOS technology projects that the minimum feature size will shrink to 0.10 ㎛ for production devices in the year 2005. The transition in production of CMOS logic circuits now underway from 0.5 ㎛ to 0.35 ㎛ CMOS demonstrates that technology shrinks are limited primarily by the need for new fabrication equipment and this will occur again at every generational change. The need for higher circuit speed without increasing power generation is driving technology towards shrunk transistors operating at lower power supply voltages. Metal interconnect RC time constant is rapidly becoming a major factor in circuit performance. In addition, interconnect layout soon may limit circuit scaling rather than transistor design. Even when interconnect limits scaling, decreasing poly gate linewidth and lowering the operating voltage can improve performance.

      • SCOPUSKCI등재

        Opioid Pharmacotherapy for Chronic Noncancer Pain: The American Experience

        Chapman, C. Richard The Korean Pain Society 2013 The Korean Journal of Pain Vol.26 No.1

        Chronic noncancer pain is a significant and growing public health challenge in the United States. Lacking effective alternative interventions for effective chronic noncancer pain management, many physicians have turned to opioid pharmacotherapy. Increased opioid prescribing brings not only gains in therapeutic benefit but also a higher incidence of adverse drug events including increased medication misuse and opioid related mortality. Currently the United States must confront the dual problems of widespread undertreated chronic noncancer pain and a prescription opioid abuse crisis. Withholding pain relieving drugs from patients in need is unjustifiable, yet drug diversion, abuse and adverse drug events have become major social as well as medical problems. At the heart of this crisis is the lack of definitive evidence about the risk to benefit ratio of opioid pharmacotherapy for chronic noncancer pain both on an individual case and on a population basis. This article describes the extent and severity of the American chronic noncancer pain problem and the history of opioid pharmacotherapy for chronic noncancer pain in the United States. It then discusses the concept of evidence based practice and reviews current evidence supporting opioid pharmacotherapy for chronic noncancer pain as well as adverse drug events related to opioid pharmacotherapy including misuse and abuse. Finally, it considers the conflict of providing pain relief versus protecting society and reviews steps that governmental agencies, industry and others are taking to contain and ultimately resolve the problems of excessive prescribing and conflicting priorities.

      • KCI등재후보
      • KCI등재

        Intangible heritage in the United States: a history of separate initiatives

        William Chapman 국립민속박물관 2019 International Journal of Intangible Heritage Vol.14 No.-

        This paper examines the history of the United States’forays into the recognition and protection of elementsof intangible heritage. It traces the beginnings of USinitiatives to programmes of the Library of Congress inthe late 1920s through several Smithsonian InstitutionProgrammes from the 1930s on, notably the SmithsonianFolklife Festival, begun in 1967 and more recently, theNEA National Heritage Fellowship Programmes. Itfurther examines the work of the National Park Serviceand Tribal Preservation Programmes, as well as themore recent Pacific Island Programmes. A final sectionexamines regional and citywide efforts to identify andconserve aspects of intangible heritage. Although the UShas officially withdrawn from participation in the workof UNESCO it is consoling to recognise the importantstrides the US has made in the effort to promote andprotect traditional modes of cultural expression and thediversity of US approaches, which is in fact in line with theobjectives of the organisation’s international Conventionfor the Safeguarding of Intangible Cultural Heritage.

      • KCI등재

        The East China Sea in DOD China Military Power Reports

        ( Bert Chapman ) 한국국방연구원 2017 The Korean Journal of Defense Analysis Vol.29 No.1

        The National Defense Authorization Act of 2000 saw Congress require the Department of Defense (DOD) to prepare an annual report on Chinese military power. This report contains classified and unclassified editions. Documenting Chinese military developments, strategy, and trends are critical parts of these reports. Beijing`s military activities in the East China Sea (ECS) are important report components. This work explains the importance of these and other DOD reports for those studying ECS developments, examines how DOD has documented Beijing`s military activities within these publicly accessible reports, and describes how members of Congress have reacted to ECS developments during the Obama Administration.

      • KCI등재후보

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