• 제목/요약/키워드: multi-physics

검색결과 668건 처리시간 0.028초

PAGAN I: MULTI-FREQUENCY POLARIMETRY OF AGN JETS WITH KVN

  • KIM, JAE-YOUNG;TRIPPE, SASCHA;SOHN, BONG WON;OH, JUNGHWAN;PARK, JONG-HO;LEE, SANG-SUNG;LEE, TAESEOK;KIM, DAEWON
    • 천문학회지
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    • 제48권5호
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    • pp.285-298
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    • 2015
  • Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. We present results from first-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to > 108.01 K and > 109.86 K, respectively. Degrees of linear polarization mL are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with mL ~ 40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.

Single-Electron Logic Cells and SET/FET Hybrid Integrated Circuits

  • Kim, S.J.;Lee, C.K.;Lee, J.U.;Choi, S.J.;Hwang, J.H.;Lee, S.E.;Choi, J.B.;Park, K.S.;Lee, W.H.;Paik, I.B.;Kang, J.S.
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제6권1호
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    • pp.52-58
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    • 2006
  • Single-electron transistor (SET)-based logic cells and SET/FET hybrid integrated circuits have been fabricated on SOI chips. The input-output voltage transfer characteristic of the SET-based complementary logic cell shows an inverting behavior where the output voltage gain is estimated to be about 1.2 at 4.2K. The SET/FET output driver, consisting of one SET and three FETs, yields a high voltage gain of 13 and power amplification with a wide-range output window for driving next circuit. Finally, the SET/FET literal gate for a multi-valued logic cell, comprising of an SET, an FET and a constant-current load, displays a periodic voltage output of high/low level multiple switching with a swing as high as 200mV. The multiple switching functionality of all the fabricated logic circuits could be enhanced by utilizing a side gate incorporated to each SET component to enable the phase control of Coulomb oscillations, which is one of the unique characteristics of the SET-based logic circuits.

Electron Paramagnetic Resonance Study of Al-incorporated ZnO:Mn Diluted Magnetic Semiconductors

  • Park, Jun Kue;Lee, K.W.;Choi, D.M.;Lee, Cheol Eui
    • Journal of the Korean Physical Society
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    • 제73권12호
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    • pp.1884-1888
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    • 2018
  • We have employed electron paramagnetic resonance spectroscopy and magnetization measurements in order to study the effect of Al-incorporation on the magnetic interactions in ZnO:Mn diluted magnetic semiconductors. Al-doping is shown to decrease the antiferromagnetic correlation and to increase the ferromagnetic interaction, which is attributed to the hydrogen-mediated ferromagnetic Mn complexes in our Mn-doped ZnO samples.

Selective Chemical Wet Etching of Si0.8Ge0.2/Si Multilayer

  • Kil, Yeon-Ho;Yang, Jong-Han;Kang, Sukil;Jeong, Tae Soo;Kim, Taek Sung;Shim, Kyu-Hwan
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제13권6호
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    • pp.668-675
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    • 2013
  • We investigate the effect of the ageing time and etching time on the etching rate of SiGe mixed etching solution, namely 1 vp HF (6%), 2 vp $H_2O_2$ (30%) and 3 vp $CH_3COOH$ (99.8%). For this etching solution, we found that the etch rate of SiGe layer is saturated after the ageing time of 72 hours, and the selectivity of $Si_{0.8}Ge_{0.2}$ layer and Si layer is 20:1 at ageing time of 72 hours. The collapse was appeared at the etching time of 9min with etching solution of after saturation ageing time.

OBSERVATIONAL STUDIES OF MAGNETICALLY ACTIVE STARS

  • BUDDlNG E.;ALLEN D.;CRAWFORD D. L.;JONES K. M.;SLEE O. B.;ZEILIK M.
    • 천문학회지
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    • 제29권spc1호
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    • pp.205-208
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    • 1996
  • Multi-wavelength observing has been particularly fruitful in cool star research. There have been some well-observed examples, eg AB Dor, though ambiguity remains. This raises issues of data information content and model parameter determinacy, which are examined firstly in an optical context. We then widen the discussion to show how multi-site and multi-wavelength data can be combined to point to better constrained models. Particular cases, involving near-simultaneous radiometry and photometry, are discussed to clarify such modelling.

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Multi-Institutional Database System for The Aid of Improvement in Radiotherapy Results

  • Ishibashi, Masatoshi;Harauchi, Hajime;Kou, Hiroko;Kumazaki, Yu;Shimizu, Keiji;Harano, Masako;Numasaki, Hodaka;Yoshioka, Munenori;Inamura, Kiyonari
    • 한국의학물리학회:학술대회논문집
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    • 한국의학물리학회 2002년도 Proceedings
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    • pp.126-128
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    • 2002
  • A learning system was built into an on-line, multi-institutional radiotherapy database, where the treatment history records and the results in each institution were integrated, each radiotherapy planning was supported, and it led to the improvement in treatment results.

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Innovative Modeling and Simulation of Reacting Flow with Complex Confined Boundaries

  • Kim, Ki-Hong;Yoh, Jai-Ick
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2008년 영문 학술대회
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    • pp.311-319
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    • 2008
  • We present an innovative method of multi physics application involving energetic materials. Energetic materials are related to reacting flows in extreme environments such as fires and explosions. They typically involve high pressure, high temperature, strong shock waves and high strain rate deformation of metals. We use an Eulerian methodology to address these problems. Our approach is naturally free from large deformation of materials that make it suitable for high strain rate multi-material interacting problems. Furthermore we eliminate the possible interface smearing by using the level sets. We heave devised a new level set based tracking framework that can elegantly handle large gradients typically found in reacting gases and metals. We show several work-in-progress application of our integrated framework.

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다중 음극 전자빔을 이용한 대면적 플라즈마 소스 (A Large Area Plasma Source Using Multi-cathode Electron Beam)

  • 강양범;전형탁;김태영;정기형;고동균;정재국;노승정
    • 한국재료학회지
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    • 제9권9호
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    • pp.861-864
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    • 1999
  • 다중 음극 전자빔을 이용한 새로운 플라즈마 소스를 설계하고 제작하였다. 대면적의 플라즈마를 발생시키기 위해 다중 음극을 채택하였다. 다중 음극 전자빔 플라즈마 소스(multi-cathode electron beam plasma source, MCEBPS)를 이용하여 300mm 또는 그 이상의 직경을 가진 웨이퍼에 안정한 플라즈마를 생성시킬 수 있었다. 텅스텐 필라멘트를 음극으로 사용하였다. 직경 320mm의 넓이에서, plasma potential $V_p$와 floating potential $V_f$ 모두 균일하게 유지되었고 $V_p와 V_f$의 차이도 낮은 값으로 나타났다. 플라즈마 밀도는 약 $10^{10} cm^{-3}$ 정도로 측정되었고 반경걸에 따른 편차는 작게 나타났다.

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