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        검색결과 369

        221.
        2005.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this paper, we have made the component-based development of observational software for KASI solar imaging spectrograph (KSIS) that is able to obtain three-dimensional imaging spectrograms by using a scanning mirror in front of the spectrograph slit. Since 2002, the KASI solar spectrograph has been successfully operated to observe solar spectra for a given slit region as well as to inspect the response functions of narrow band filters. To improve its capability, we have developed the KSIS that can perform sequential observations of solar spectra by simultaneously controlling the scanning mirror and the CCD camera via Visual C++. Main task of this paper is to introduce the development of the component-based software for KSIS. Each component of the software is reusable on the level of executable file instead of source code because the software was developed by using CBD (component-based development) methodology. The main advantage of such a component-based software is that key components such as image processing component and display component can be applied to other similar observational software without any modifications. Using this software, we have successfully obtained solar imaging spectra of an active region (AR 10708) including a small sunspot. Finally, we present solar Hα spectra (6562.81 Å) that were obtained at an active region and a quiet region in order to confirm the validity of the developed KSIS and its software.
        4,000원
        222.
        2005.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In a companion paper, we have presented so-called Spatio-Spectral Maximum Entropy Method (SSMEM) particularly designed for Fourier-Transform imaging over a wide spectral range. The SSMEM allows simultaneous acquisition of both spectral and spatial information and we consider it most suitable for imaging spectroscopy of solar microwave emission. In this paper, we run the SSMEM for a realistic model of solar microwave radiation and a model array resembling the Owens Valley Solar Array in order to identify and resolve possible issues in the application of the SSMEM to solar microwave imaging spectroscopy. We mainly concern ourselves with issues as to how the frequency dependent noise in the data and frequency-dependent variations of source size and background flux will affect the result of imaging spectroscopy under the SSMEM. We also test the capability of the SSMEM against other conventional techniques, CLEAN and MEM.
        5,200원
        223.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        통증은 다른 일반 감각과는 달리 감각적인 면과 정서적인 면이 있어, 인격, 기대, 암시, 과거 통증경험과 같은 개인의 심리적 특성이나 사회문화적 환경 등 여러 요인에 의해 크게 영향을 받는다. 이러한 환자의 주관적인 통증의 호소를 객관화하려는 노력은 여러 통증 치료 의사들한테 많이 시도되어 왔으나 아직도 정확한 객관적인 진단방법이 나타나고 있지 않다. 최근에 PET이나 fMRI의 등장은 이러한 면에서 통증에 관한 연구를 하는 학자들에게 커다란 도움을 주고 있고 현재에도 이러한 뇌 기능적 자기공명영상을 이용한 많은 연구결과들이 보고되고 있다. 뇌는 어떠한 기능을 수행하기 위하여 특정부위의 뇌 신경활동이 항진되면 이와 함께 그 부위의 국소적 뇌 혈류 및 대사가 증가하는 것으로 알려져 있다. 이러한 생리적 변화를 이용하여 뇌에 국소적 신경활성화가 생기는 위치를 mapping 할 수 있다. mapping 대상 뇌 기능은 지각, 운동, 기억, 언어 등의 기능에서 출발하여 최근 감정, 정서, 사회적 인식, 도덕적 판단, 의식, 마음까지 조사대상이 넓어지고 있다. 본 발표에서는 이러한 뇌 기능 영상기법에 대한 내용과 뇌 기능 영상 기법을 이용하여 통증의 평가를 어떻게 할 수 있는지를 알아보고자 한다.
        4,000원
        228.
        2005.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the high-resolution (2"-4") images of the molecular envelopes surrounding the evolved stars, V Hya, VY CMa, and π1 Gru observed with the Submillimeter Array. The CO J=2-1 and 3-2 images of the carbon star V Hya show that the circumstellar structure of this star consists of three kinematic components; there is a flattened disk-like envelope that is expanding with a velocity of ~16 km s-1, the second component is the medium-velocity wind having a deprojected velocity of 40-120 km s-l moving along the disk plane, and the third one is the bipolar molecular jet having an extreme velocity of 70-185 km s-l. The axis of this high velocity jet is perpendicular to the plane of the disk-like envelope. We found that the circumstellar structure of the S-star π1 Gru traced by the CO J =2-1 resembles that of V Hya quite closely; the star is surrounded by the expanding disk-like envelope and is driving the medium-velocity wind along the disk plane. We also obtained the excellent images of VY CMa with the CO and 13CO J=2-1 and SO 65-54 lines. The maps of three molecular lines show that the envelope has a significant velocity gradient in the east-west direction, suggesting that the envelope surrounding VY CMa is also flattened and expanding along its radial direction. The high-resolution images obtained with the SMA show that some AGB stars are associated with the asymmetric mass loss including the equatorial wind and bipolar jet.
        3,000원
        229.
        2005.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The FIMS (Far-ultraviolet IMaging Spectrograph; also known as SPEAR, Spectroscopy of Plasma Evolution from Astrophysical Radiation) is the primary payload of the STSAT-1, the first Korean science satellite, which was launched in September, 2003. The FIMS performs spectral imaging of diffuse far-ultraviolet emission with the unprecedented wide field of view and the relatively good spectral resolution. We present far-ultraviolet spectral observations of highly ionized interstellar medium including supernova remnants, superbubbles, soft X-ray shadows, and the molecular hydrogen fluorescent emission lines. The FIMS has detected He II, C III, 0 III, O IV, Si IV, O VI, and H2 fluorescent emission lines. The emission lines arise in shocked or thermally heated and in photo-ionized gases. We present an overview of the FIMS instrument and its initial observational results.
        3,000원
        232.
        2004.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We find evidence of a hard X-ray excess above the thermal emission in two cool clusters (Abell 1750 and IC 1262) and a soft excess in two hot clusters (Abell 754 and Abell 2163). Our modeling shows that the excess components in Abell 1750, IC 1262, and Abell 2163 are best fit by a steep power law indicative of a significant non-thermal component. In the case of Abell 754, the excess emission is thermal, 1 ke V emission. We analyze the dynamical state of each cluster and find evidence of an ongoing or recent merger in all four clusters. In the case of Abell 2163, the detected, steep spectrum, non-thermal X-ray emission is shown to be associated with the weak merger shock seen in the temperature map. However, this shock is not able to produce the flatter spectrum radio halo which we attribute to post-shock turbulence. In Abell 1750 and IC 1262, the shocked gas appears to be spatially correlated with non-thermal emission suggesting cosmic-ray acceleration at the shock front.
        4,000원
        233.
        2004.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have developed a wide-field imaging camera system, called WICZO, to monitor light of the night sky over extended period. Such monitoring is necessary for studying the morphology of interplanetary dust cloud and also the time and spatial variations of airglow emission. The system consists of an electric cooler a CCD camera with 60% quantum efficiency at 500nm, and a fish-eye lens with 180 ̊ field of view. Wide field imaging is highly desired in light of the night sky observations in general, because the zodiacal light and the airglow emission extend over the entire sky. This paper illustrates the design of WICZO, reports the result of its laboratory performance test, and presents the first night sky image, which was taken, under collaboration with Byulmaro Observatory, on top of Mt. Bongrae at Yongweol in January, 2004.
        4,000원
        236.
        2003.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Optical (R) and near-infrared (K') images of the IRAS 1-Jy sample of 118 ultraluminous infrared galaxies have been studied. All but one object in the 1-Jy sample show signs of strong tidal interaction/merger. Most of them harbor a single disturbed nucleus and are therefore in the later stages of a merger event. Single-nucleus ULIGs show a broad distribution in host magnitudes with significant overlap with those of quasars. The same statement applies to R - K' colors in ULIG and quasar hosts. An analysis of the surface brightness profiles of the host galaxies in single-nucleus sources reveals that about 35% of the Rand K' surface brightness profiles are well fit by an elliptical-like R1/4-law, while only 2% are well fit by an exponential disk. Another 38% of the single-nucleus systems are fit equally well with an exponential or de Vaucouleurs profile. Elliptical-like hosts are most common among merger remnants with Seyfert 1 nuclei (83%) and Seyfert 2 optical characteristics (69%). The mean effective radius of these ULIGs is 4.80 ± 1.37 kpc at R and 3.48 ± 1.39 kpc at K'. These values are in excellent agreement with recent quasar measurements obtained at H with HST. The hosts of elliptical-like 1-Jy systems follow with some scatter the same μe - re relation, giving credence to the idea that some of these objects may eventually become elliptical galaxies if they get rid of their excess gas or transform this gas into stars.
        4,000원
        238.
        2003.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        LIST is the Lyman-α Imaging Solar Telescope, a project funded by the Korean government to fly on the second Korean Science and Technology research Satellite (STSat-2) due to launch in December 2005. The Principal Investigator is Dr. Minhwan Jang of Kyung-Hee University and of the Space Payload Research Center (SPARC), a consortium of Korean universities and institutions formed to develop scientific research projects in space. The purpose of the LIST project is to design, build, and operate an instrument on STSat-2 which will make images of the Sun from Earth orbit at the wavelength of the Hydrogen Lyman-a emission line at 121.6 nm. LIST has a simple design concept comprised of a small telescope to image the full disk of the Sun onto a CCD detector and a set of filters to isolate the 121.6 nm wavelength.
        4,000원
        240.
        2002.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Inverse synthetic aperture radar(ISAR)를 이용하여 콘크리트의 비파괴 검사시 필요한 적정 주파수 대역폭을 결정하기 위해 주파수 합성을 실시하였다. 콘크리트 시편의 내부를 영상화하기 위한 레이더 신호처리 기법을 이용하여 레이더 주파수 2~3.4 GHz, 3.4~5.8 GHz 대역에서 무근 콘크리트 시편과 내부 공동 또는 철근이 있는 콘크리트 시편을 대상으로 실험하였다. 분해능을 높이기 위해 두 측정 주파수 대역을 합성한 2~5.8 GHz대역에서 신호처리를 하여 영상화 결과를 향상시켰다. 주파수 대역폭 변화에 따른 콘크리트 시편 비파괴 검사 결과의 영향을 분석하였다.
        4,000원