• Title/Summary/Keyword: ISM: general

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The impact of ram pressure on the multi-phase ISM probed by the TIGRESS simulation

  • Choi, Woorak;Kim, Chang-Goo;Chung, Aeree
    • The Bulletin of The Korean Astronomical Society
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    • v.43 no.1
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    • pp.62.1-62.1
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    • 2018
  • Galaxies in the cluster environment interact with the intracluster medium (ICM), losing the interstellar medium (ISM) and alternating their evolution. Observational evidences of the extraplanar ISM stripped by the ICM's ram pressure are prevalent in HI imaging studies of cluster galaxies. However, current theoretical understanding of the ram pressure stripping (or ICM-ISM interaction in general) is still limited mainly due to the lack of numerical resolution at ISM scales in large-scale simulations. Especially, self-consistent modeling of the turbulent, multiphase ISM is critical to understand star formation in galaxies interacting with the ICM. To achieve this goal, we utilize the TIGRESS simulation suite, simulating a local patch of galactic disks with high resolution to resolve key physical processes in the ISM, including cooling/heating, self-gravity, MHD, star formation, and supernova feedback. We then expose the ISM disk to ICM flows and investigate the evolution of star formation rate and the properties of the ISM. By exploring ICM parameter space, we discuss an implication of the simple ram pressure stripping condition (so called the Gunn-Gott condition) to the realistic ISM.

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A Contingent Analyses on the Relationship Between the Characteristics of Internet Shopping Mall and User Acceptance (인터넷 쇼핑몰의 특성과 사용자 수용간의 상황적 관계분석)

  • Suh, Kun-Soo
    • Asia pacific journal of information systems
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    • v.11 no.2
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    • pp.23-55
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    • 2001
  • It is generally agreed that realizing the full potential of the internet shopping mall(ISM) requires careful identification of customer needs and expectations. However, a quantitative framework to explain and predict users' behavior toward ISM has not been well established because the research on the user acceptance of ISM is still in its infancy. This study proposes a model which uses factor analysis to identify factors of ISM characteristics and individual characteristics affecting user acceptance of ISM. Predictive models based on the multiple regression analyses select the factors and their interactions with individual characteristics that significantly influence user acceptance. Results show that five factors including economy, convenience, credibility, reliability, information risks, and performance risks affects user acceptance. In addition, individual differences in terms of innovativeness, playfulness, and recreational shopping traits have both direct and interaction effects on user acceptance. The implication of this study is that, although user attitudes towards ISM characteristics in general are important to their acceptance behavior, the level of importance depends upon different user groups.

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SUPERBUBBLES AS SPACE BAROMETERS

  • GARCIA-SEGURA G.;OEY M. S.
    • Journal of The Korean Astronomical Society
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    • v.37 no.4
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    • pp.217-222
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    • 2004
  • High ambient interstellar pressure is suggested as a possible factor to explain the ubiquitous ob-served growth-rate discrepancy for supernova-driven super bubbles and stellar wind bubbles. Pressures of P / k ${\~} 10^5\;cm^{-3}$ K are plausible for regions with high star formation rates, and these values are intermediate between the estimated Galactic mid-plane pressure and those observed in starburst galaxies. High-pressure components also are commonly seen in Galactic ISM localizations. We demonstrate the sensitivity of shell growth to the ambient pressure, and suggest that super bubbles ultimately might serve as ISM barometers.

PROCESSING OF INTERSTELLAR MEDIUM AS DIVULGED BY AKARI

  • Onaka, Takashi;Mori, Tamami I.;Ohsawa, Ryou;Sakon, Itsuki;Bell, Aaron C.;Hammonds, Mark;Shimonishi, Takashi;Ishihara, Daisuke;Kaneda, Hidehiro;Okada, Yoko;Tanaka, Masahiro
    • Publications of The Korean Astronomical Society
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    • v.32 no.1
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    • pp.77-81
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    • 2017
  • A wide spectral coverage from near-infrared (NIR) to far-infrared (FIR) of AKARI both for imaging and spectroscopy enables us to efficiently study the emission from gas and dust in the interstellar medium (ISM). In particular, the Infrared Camera (IRC) onboard AKARI offers a unique opportunity to carry out sensitive spectroscopy in the NIR ($2-5{\mu}m$) for the first time from a spaceborn telescope. This spectral range contains a number of important dust bands and gas lines, such as the aromatic and aliphatic emission bands at 3.3 and $3.4-3.5{\mu}m$, $H_2O$ and $CO_2$ ices at 3.0 and $4.3{\mu}m$, CO, $H_2$, and H I gas emission lines. In this paper we concentrate on the aromatic and aliphatic emission and ice absorption features. The balance between dust supply and destruction suggests significant dust processing taking place as well as dust formation in the ISM. Detailed analysis of the aromatic and aliphatic bands of AKARI observations for a number of H ii regions and H ii region-like objects suggests processing of carbonaceous dust in the ISM. The ice formation process can also be studied with IRC NIR spectroscopy efficiently. In this review, dust processing in the ISM divulged by recent analysis of AKARI data is discussed.

INFRARED SUPERNOVA REMNANTS IN THE LARGE MAGELLANIC CLOUD

  • Seok, J.
    • Publications of The Korean Astronomical Society
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    • v.27 no.4
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    • pp.231-234
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    • 2012
  • We present preliminary results of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) seen by AKARI as well as Spitzer. By examining the AKARI LMC survey and the Spitzer data, we have searched for IR counterparts to 45 known SNRs in the LMC and could identify 28 SNRs with associated IR emission. 13 SNRs among them are newly detected in IR bands. For the entire IR SNRs, we make a catalog containing general information and the AKARI and/or Spitzer fluxes. Using the catalog, their IR colors and the possible correlation of the IR fluxes with the X-ray fluxes are examined. For some interesting SNRs, we have performed NIR spectroscopy with AKARI. An aromatic feature at $3.3{\mu}m$ can be identified in LMC SNR N49. We investigate the characteristics of the IR features and discuss the PAH mission mechanism in SNRs.

Design of Wideband Microstrip Patch Antenna (광대역 마이크로스트립 패치 안테나 설계)

  • Kim, Tae Yong;Lee, Jong-Ig
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.469-470
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    • 2015
  • General microstrip patch antenna has small bandwidth. Also this patch antenna is strongly influenced by the thickness of dielectric substrate and its relative permittivity. In this paper, wideband microstrip patch antenna operating in 2.4GHz ISM band is studied. Input impedance and return loss for designed microstrip patch antenna by using MoM method and is estimated.

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Estimation of Microstrip Patch Antenna corresponding to Feed Positions (마이크로스트립 패치 안테나의 급전 위치에 따른 평가)

  • Kim, Tae Yong;Lee, Jong-Ig
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.473-474
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    • 2015
  • General microstrip patch antenna has small bandwidth. Input impedance of patch antenna corresponding to feed positions and its feed model is strongly varied. In this paper, wideband microstrip patch antenna operating in 2.4GHz ISM band is investigated. Using the MoM, the variation with feed position of the input impedance of a patch antenna is estimated.

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Estimation for Input Impedance of Microstrip Patch Antenna corresponding to Cutting Shape (마이크로스트립 패치 절단 모양에 따른 입력 임피던스 평가)

  • Kim, Tae Yong;Lee, Jong-Ig
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.480-481
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    • 2015
  • General microstrip patch antenna has small bandwidth. If corner of a patch antenna is properly cutted to be triangular shape, then input impedance of patch antenna should be varied. Using this characteristic wideband patch antenna can be implemented. In this paper, wideband microstrip patch antenna operating in 2.4GHz ISM band is investigated through tracking variation of input impedance corresponding to cutting shape of patch antenna.

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PDF properties of ISM turbulence

  • Jo, Hyeon-Jin;Gang, Hye-Seong;Ryu, Dong-Su;Kim, Jong-Su;Jo, Jeong-Yeon
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.107.1-107.1
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    • 2011
  • Density Probability Distribution Functions (PDFs) are a classic statistical way to study properties of Interstellar Medium (ISM) turbulence. In our three-dimensional MHD simulations, density PDFs of the position-position velocity (PPV) spaces are close to a log-normal distribution. the PDF widths depend on the plasma parameters such as magnetic strength and sonic Mach number. Futhermore, we compare these simulations results to Galactic molecular clouds observed by Jackson et. al (2006). By fitting of the velocity dispersion in the spectral line observation, volume density PDFs of the defined molecular clouds indicate that the sound speeds of the turbulences seem to have a few times larger than the simulation results. In order to understand the inconsistency with general characteristics of turbulence, we consider other simulations inducing the turbulent flow randomly at small driving scales. We find that the density PDF width decreases at more smaller driving scale. Finally, the simulations suggest that sources of ISM turbulence in Galactic molecular clouds can be important on small scales.

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Transformation Methodology : From the Farmer Model To Component Interface meta Model

  • Park, Soo-Hyun;Min, Sung-Gi;Kim, Tai-Suk
    • Proceedings of the IEEK Conference
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    • 2000.07a
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    • pp.545-548
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    • 2000
  • A fundamental tenet of CBD is that a component has a specification which describes what that component does, and how it behaves when its services are used. In general, the implementation may be written in a different programming language and execute on different technology platform, from the language and platform used by the client program. In order to implement practically the system that is designed by the Farmer model, there is need to have the ISM (Interface Specification Model) which explains specification about the functions of entities of the Farmer model, such as, entity node, aspect node and ILB/OLB. This paper suggests the transformation methodology from the concepts of the Farmer model to the mapping notions of the ISM. Also in reality, TMN agents system which is designed by the Farmer model is transformed to the ISM system design.

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