• 제목/요약/키워드: V-B curves

검색결과 136건 처리시간 0.022초

SERKOWSKI'S EMPIRICAL RELATION FOR INTERSTELLAR LINEAR POLARIZATION VIEWED FROM DAVIS-GREENSTEIN ALIGNMENT MECHANISM

  • Hong, Seung-Soo;Lee, Hyung-Mok
    • 천문학회지
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    • 제11권1호
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    • pp.31-36
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    • 1978
  • Although Serkowski used a single value K=1.15 in representing all the observed interstellar linear polarization curves by his empirical relation $p({\lambda})/P_{max}$=exp (-K $1n^2({\lambda}_{max}/{\lambda})$), where $p_{max}$ is the maximum polarization at wavelength ${\lambda}_{max}$, we have noticed a meaningful variation in K from observations of 72 stars. By comparing K's with $P_{max}/E_{B-V}\;and\;with\;{\lambda}_{max}$, we have examined how the shape of the polarization curve is related with the degree of grain alignment on one hand, and with grain sizes on the other. We have shown that correlations between K, $P_{max}/E_{B-V}\;and\;with\;{\lambda}_{max}$, are consistent with the idea of Davis-Greenstein mechanism for grain alignment.

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BVRI PHOTOMETRY OF VV CEPHEI

  • Nha, Il-Seong;Im, Hong-Seo;Lee, Yong-Sam;Jeong, Jang-Hae
    • Journal of Astronomy and Space Sciences
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    • 제9권1호
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    • pp.89-96
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    • 1992
  • UBV observations of VV Cep were made in 1988-1992 as a part of the Ten-year Observing Program for Long Period Eclipsing Binary Stars(1982-1992) at Yonsei University Observatory. In addition to these the observations in the longer passbands in R and I are also made in the 1991-1992 season at the same observatory. Atmospheric extinction coefficinets determined by a comparison star 20 Cap for B and V each night have been deduced a linear relation, $K_B$=0.159+1.066kV. In this paper, light curves of this star in BVRI passbands for the 1991-1992 season only are presented. Two periodic light variations of both long-term and short-term are found as for 90 days and 20 days, respectively.

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비축대칭 H-형 및 U-형상의 압출금형 곡면의 자동생성 (Automatic Surface Generation for Extrusion Die of Non-symmetric H- and U-shaped Sections)

  • 임종훈;유동진;양동열
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 추계학술대회논문집
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    • pp.318-321
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    • 2003
  • In order to generate the extrusion die surface of non-symmetric H- and U-shaped sections, an automatic surface construction method based on B-spline surface and scalar field theory is proposed in this study. The isothermal lines and stream lines designed in the scalar field are introduced to find the control points which are used in constructing B-spline surfaces. Intersected points between the isothermal lines and stream lines are used to construct B-spline surfaces. The inlet and outlet profiles are precisely described with B-spline curves by using the centripetal method for uniform parameterization. The extrusion die surface is generated by using the cubic curve interpolation in the u- and v-directions. A quantitative measure for the control of surface is suggested by introducing the tangential vectors at the inlet and outlet sections.

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복잡한 형상의 압출금형 곡면의 자동생성 (Automatic Surface Generation for Extrusion Die of Complicated Sections)

  • 임종훈;유동진;권혁홍;양동열
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 추계학술대회논문집
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    • pp.197-200
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    • 2003
  • An automatic surface construction method based on B-spline surface and scalar field theory is proposed to generate the extrusion die surface of complicated sections in this paper. The isothermal lines and stream lines designed in the scalar field are introduced to find the control points which are used in constructing B-spline surfaces. Intersected points between the isothermal lines and stream lines are used to construct B-spline surfaces. The inlet and outlet profiles are precisely described with B-spline curves by using the centripetal method for uniform parameterization. The extrusion die surface is generated by using the cubic curve interpolation in the u- and v-directions. A quantitative measure for the control of surface is suggested by introducing the tangential vectors at the inlet and outlet sections.

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비축대칭 H-형 및 U-형상의 압출금형 곡면의 자동생성 (Automatic Surface Generation for Extrusion Die of Non-symmetric H-and U-shaped sections)

  • 유동진;임종훈;양동열
    • 소성∙가공
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    • 제12권6호
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    • pp.572-581
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    • 2003
  • In this paper, an automatic surface construction method based on B-spline surface and scalar field theory is proposed to generate the extrusion die surface of non-symmetric H-and U-shaped sections. The isothermal lines and stream lines designed in the scalar field are introduced to find the control points which are used in constructing B-spline surfaces. Intersected points between the isothermal lines and stream lines are used to construct B-spline surfaces. The inlet and outlet profiles are precisely described with B-spline curves by using the centripetal method for uniform parameterization. The extrusion die surface is generated by using the cubic curve interpolation in the u-and v-directions. A quantitative measure for the control of surface is suggested by introducing the tangential vectors at the inlet and outlet sections. To verify the validity of the proposed method, automatic surface generation is carried out for extrusion die of non-symmetric H-and U-shaped sections.

상호작용이 심한 장주기 근접 쌍성계 AQ Cas의 측광학적 연구 (THE PHOTOMETRIC STUDY FOR THE LONG PERIOD INTERACTION CLOSE BINARY AQ CAS)

  • 이용삼;전용우
    • Journal of Astronomy and Space Sciences
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    • 제8권1호
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    • pp.73-83
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    • 1991
  • 조기형 근접쌍성 AQ Cas를 1982년부터 1989년까지 (총 91일 밤) 연세대학교 천문대 일산 관측소에서 관측하여 UBV 광도곡선을 완성하였다. U의 광도곡선으로부터 두 별사이에 물질이동으로 인하여 위상 0.55와 0.90근처에서 광도가 어두워지는 현상을 확인하였다. 우리의 관측점으로 4개의 식심시각을 결정하였고, 수집한 식심 시각을 가지고 새로운 광도요소를 얻었다. 또한, BV 광도곡선을 가지고 Wilson-Devinney 계산법으로 측광 궤도요소들을 구하였다.

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PHOTOMETRIC STUDY OF THE W UMA SYSTEM U PEGASI

  • Lee, Y.S.;Jeong, J.H.;Park, S.H.;Lee, C.U.;Woo, J.O.
    • Journal of Astronomy and Space Sciences
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    • 제15권1호
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    • pp.75-82
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    • 1998
  • A total of 842 observations (277 in B, 282 in V, and in R) for U Pegasi were made in October of 1996 at Mt. Sobaek Observatory. With our data we constructed the BVR light curves and determinded 5 times of minimum light. We also obtained physical parameters of the system by combined analysis of both light and radial velocity curves using the Wilson-Devinney code.

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VARIABLE STARS IN A FIELD OF THE OLD OPEN CLUSTER M67 PHOTOMETRIC PRECISION OF THE BOAO 1.8M TELESCOPE

  • KIM SEUNG-LEE;CHUN MOO-YOUNG;PARK BYEONG-GON;LEE SEE-WOO
    • 천문학회지
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    • 제29권1호
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    • pp.43-51
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    • 1996
  • We present test results of time-series CCD photometry to investigate the photometric precision of the BOAO (Bohyunsan Optical Astronomy Observatory) 1.8m telescope. A well-known field of the old open cluster M67, which includes two pulsating blue stragglers and two W UMa type binaries, was monitored for 3.5 hours on February 22, 1996. We have collected 148 V frames and 3 B frames. Photometric noises which consist mainly of photon noise and scintillation noise, were lowered down to about 1.9 mmag for stars of $10.\;^m5$ in M67 with exposure time of 20 seconds. From the C-M diagram for M67, a number of observational properties were derived; E(B-V) = 0.03, (V-Mv)o = 9.6, Age = 4 Gyr. We obtained light curves for four known variable stars and confirmed their variational characteristics. The pulsating blue stragglers show a low amplitude (about 0.01 mag) of light variation.

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A simple model for selection and rapid advancement of transgenic progeny in sorghum

  • Visarada, K.B.R.S.;Saikishore, N.;Kuriakose, S.V.;Rani, V. Shobha;Royer, M.;Rao, S.V.;Seetharama, N.
    • Plant Biotechnology Reports
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    • 제2권1호
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    • pp.47-58
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    • 2008
  • To select agronomically useful transgenic plants, a large number of transgenic events are initially produced, gene transfer confirmed, and advanced to obtain homozygous lines for testing in field trials. Direct in planta assays for identifying the transgene carriers in the segregating progeny are based on the activity of selectable marker gene and are easy, simple and inexpensive. For this purpose, expression of bar gene as measured by tolerance to damage by glufosinate ammonium, the active ingredient in the herbicide BASTA, was investigated. Dose damage curves were generated by leaf paint tests with BASTA on four genotypes of sorghum. Transgenic plants were characterized in terms of sensitivity to the concentration of glufosinate ammonium. In transgenics, symptoms of BASTA swab tests at different growth stages and PCR analysis for cry1B were carried out and correlated. Germination tests could not be employed for large scale evaluation of transgenic progeny because of mortality of tolerant seedlings after transplantation to soil. Based on the above findings, a simple, inexpensive, time-saving, two-step scheme for effective evaluation of transgenics and their progeny containing bar gene as selection marker using BASTA swab tests is described.

Evaluation of Radio-Frequency Performance of Gate-All-Around Ge/GaAs Heterojunction Tunneling Field-Effect Transistor with Hetero-Gate-Dielectric by Mixed-Mode Simulation

  • Roh, Hee Bum;Seo, Jae Hwa;Yoon, Young Jun;Bae, Jin-Hyuk;Cho, Eou-Sik;Lee, Jung-Hee;Cho, Seongjae;Kang, In Man
    • Journal of Electrical Engineering and Technology
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    • 제9권6호
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    • pp.2070-2078
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    • 2014
  • In this work, the frequency response of gate-all-around (GAA) Ge/GaAs heterojunction tunneling field-effect transistor (TFET) with hetero-gate-dielectric (HGD) and pnpn channel doping profile has been analysed by technology computer-aided design (TCAD) device-circuit mixed-mode simulations, with comparison studies among ppn, pnpn, and HGD pnpn TFET devices. By recursive tracing of voltage transfer curves (VTCs) of a common-source (CS) amplifier based on the HGD pnpn TFET, the operation point (Q-point) was obtained at $V_{DS}=1V$, where the maximum available output swing was acquired without waveform distortion. The slope of VTC of the amplifier was 9.21 V/V (19.4 dB), which mainly resulted from the ponderable direct-current (DC) characteristics of HGD pnpn TFET. Along with the DC performances, frequency response with a small-signal voltage of 10 mV has been closely investigated in terms of voltage gain ($A_v$), unit-gain frequency ($f_{unity}$), and cut-off frequency ($f_T$). The Ge/GaAs HGD pnpn TFET demonstrated $A_v=19.4dB$, $f_{unity}=10THz$, $f_T=0.487$ THz and $f_{max}=18THz$.