• 제목/요약/키워드: angular correlation effect

검색결과 19건 처리시간 0.026초

Calculation of Effective Angular Correlation in the HPGe Spectroscopy of Co-60 $\gamma$-rays

  • Kim, In-Jung;Sun, Gwang-Min;Park, H. D.;Bae, Young-Dug
    • Nuclear Engineering and Technology
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    • 제34권1호
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    • pp.22-29
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    • 2002
  • The angular correlation effect was investigated for Co-60 ${\gamma}$-ray spectroscopy by using HPGe detector and the effective angular correlation was theoretically calculated by considering the finite detector solid angle. For the calculation of effective angular correlation, the detection efficiency as a function of ${\gamma}$-ray incident direction was obtained by using Monte Carlo method and the first interaction model. The results and the methods used in the calculation are discussed.

건드림된 프리이드만 시공간 속의 각지름 거리: 중력파의 효과 (ANGULAR DIAMETER DISTANCE IN PERTURBED FRIEDMANN SPACETIME: EFFECTS OF GRAVITATIONAL WAVES)

  • 송두종
    • 천문학논총
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    • 제19권1호
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    • pp.1-10
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    • 2004
  • On the framework of a linearly perturbed Friedmann-Robertson-Walker spacetime, we derive an expression for the cosmological angular diameter distance affected by scalar and tensor perturbations. Our expression is applicable in linear order to distances in general FRW models. We study the effect of a stocastic gravitaional wave background on the two-point correlation function of the angular diameter distance fluctuations and, on the basis of this we also derive an expression for the power spectrum of the angular diameter distance fluctuations.

Moleciular Reorientation in the Presence of the Extended Diffusion of internal Rotation in Liquid Perdeuterotoluene

  • Doo-Soo Chung;Myung-Soo Kim;Jo-Woong Lee;Kook-Joe Shin
    • Bulletin of the Korean Chemical Society
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    • 제4권1호
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    • pp.25-28
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    • 1983
  • The effect of internal rotation of methyl group in liquid perdeuterotoluene on nuclear quadrupole relaxation of methyl deuterons is investigated. A model of a spherical diffusor undergoing rotational diffusion is extended to include the extended diffusion of internal rotation. The overall reorientational correlation time in the presence of internal rotation is explicitly given as an analytical function of the angular momentum correlation time. Also, the degree of inertial effect in the internal rotation is evaluated.

골프 드라이버 스윙 시 임팩트 전·후 신체 균형성이 클럽헤드의 속도와 각도에 미치는 영향 (Effect of Balance before and after Impact on the Velocity and Angle of Golf Club during Driver Swing)

  • 류지선;김태삼
    • 한국운동역학회지
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    • 제21권4호
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    • pp.411-420
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    • 2011
  • The purpose of this investigation was to determine whether correlations exist between balance and impact velocity, angular position, and maximum velocity of a club during drive swing. Twelve skilled golfers were recruited in this study. They were asked to perform ten swing trials and two trials were selected for analysis. Balance parameters were calculated via the force platform while kinematic variables were determined by using the Qualisys system. The results of the present study demonstrated that the average of COP velocity was faster in the medio-lateral direction rather than the anterio-posterior direction. Also, left foot's COP velocity and free torque were greater than the right foot's before impact. The range of the right foot's COP in the anterio-posterior direction before impact were correlated with the club velocity and angular position at impact. There was a negative correlation between the left foot's COP velocity before the impact and the velocity at impact. Additionally, the range and RMS of the left foot's free torque affected on the club angular position at impact and the maximum velocity at release, respectively. Finally, a negative correlation existed between the range of the right foot's free torque after the impact and club's maximum velocity at release.

Comparison of Cone Model Parameters for Halo Coronal Mass Ejections

  • Na, Hyeon-Ock;Moon, Yong-Jae
    • 천문학회보
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    • 제36권2호
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    • pp.96.1-96.1
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    • 2011
  • Halo coronal mass ejections (HCMEs) are major cause of the geomagnetic storms. To minimize the projection effect by coronagraph observations, we consider two CME cone models: an ice-cream cone model and an asymmetric cone model. These models allow us to determine three dimensional parameters of HCMEs such as radial speed, angular width, and the angle between sky plane and cone axis. In this study, we compare these parameters obtained from both models using 50 well-observed HCMEs from 2001 to 2002. Then we obtain the root mean square error (RMS error) between measured projection speeds and estimated ones for the models. As a result, we find that the radial speeds obtained from the models are well correlated with each other (R=0.89), and the correlation coefficient of angular width is 0.68. The correlation coefficient of the angle between sky plane and cone axis is 0.42, which is much smaller than what is expected. The reason may be due to the fact that the source locations of the asymmetric cone model are assumed to be near the center. The average RMS error of the asymmetric cone model (86.2km/s) is slightly smaller than that of the ice-cream cone model (88.6km/s).

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시-공간 벡터 채널에서 배열 안테나를 적용한 DS-CDMA 시스템의 대역폭과 각도 퍼짐에 따른 효과 (Performance Analysis of DS-CDMA System with Smart Antenna for Angular Spread and Bandwith in Spatio-temporal Vector Channel)

  • 전준수;유중찬;박현수;최민석;김철성
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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    • pp.83-86
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    • 2004
  • In this paper, the performance of wideband CDMA system with smart antenna is analyzed for different bandwidth(1.25MHz, 2.5MHz, 5MHz) and angular spread at base station. In detail, the spatio-temporal wideband multipath vector channel model is proposed. And the received signals in 2D-RAKE receiver are rigorously analyzed in proposed vector channel model. We consider the effect of correlation between any two elements of antenna array. Several multipahts within one chip are distinguished into each one and the strongest signal is selected as a desired one. As a result, the performance of W-CDMA system with smart antenna in spatio-temporal wideband vector channel has been improved in proportion to the increase of angular spread and bandwidth.

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고정도 열변위보정을 위한 주축대의 열적굽힘에 대한 연구 (Research into Head-body Thermal Bending for High-accuracy Thermal Error Compensation)

  • 김태원;하재용;고태조
    • 한국정밀공학회지
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    • 제19권1호
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    • pp.56-64
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    • 2002
  • Machine tools are engineered to give high dimensional accuracy in machining operation. However, errors due to thermal effects degrade dimensional accuracy of machine tools considerably, and many machine tools are equipped with thermal error compensation function. In general, thermal errors can be generated in the angular directions as well as linear directions. Among them, thermal errors in the angular directions contribute a large amount of error components in the presence of offset distance as in the case of Abbe error. Because most of thermal error compensation function is based on a good correlation between temperature change and thermal deformation, angular thermal deformation is often to be the most difficult hurdle for enhancing compensation accuracy. In this regard, this paper investigates the effect of thermal bending to total thermal error and gives how to deal with thermally induced bending effects in thermal error compensation.

Co-60과 Cs-134의 연발감마선에 대한 방향 및 편극상관 측정 (Measurements of the Direction and Polarization Correlation for Cascade Gamma-rays of Co-60 and Cs-134)

  • Hyung-Ju Woo;Kie-Hyung Chung;Hae-Ill Bak
    • Nuclear Engineering and Technology
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    • 제14권2호
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    • pp.64-69
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    • 1982
  • 동시섬광분석기를 써서, 각도범위 90$^{\circ}$에서 180$^{\circ}$에 대하여, Co-60 및 Cs-134 감마선의 방향상관을 측정하였다. 그리고, 방향-편극상관의 측정에는 컴프턴산란효과를 응용한 감마선 편광분광기를 병용하였다. 이론적인 배경과 더불어 실험방법이 기술되었으며, 측정값이 이론적인 개산치와 일치함을 보이기위해 실험결과를 도식적으로 나타내었다.

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Light Output Characteristics of Rounded Prism Films in the Backlight Unit for Liquid Crystal Display

  • Lee, Won-Gyu;Jeong, Jin-Ha;Lee, Ji-Young;Nahm, Kie-Bong;Ko, Jae-Hyeon
    • Journal of Information Display
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    • 제7권4호
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    • pp.1-4
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    • 2006
  • The optical performances of rounded prism films were investigated using a ray tracing technique. The angular distribution of the luminous intensity was obtained as functions of the prism pitch and the curvature of rounded apex and valley of prism arrays. The gain of the on-axis luminance decreased with decreasing curvature (increasing diameter) and pitch. The existence of the curved area on the prism film decreased the recycling efficiency of the prism film, i.e., the rays which would otherwise have been recycled through total internal reflections via the prism surfaces were refracted on the curved regions and redirected toward directions other than the on-axis direction. Quantitative correlation between the luminance gain and the curvature in addition to the prism pitch was obtained, which might serve as basic data for the optimization of prism films and the manufacturing processes.

Comparison to Cone Models for Halo Coronal Mass Ejections

  • Na, Hyeon-Ock;Moon, Yong-Jae
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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    • pp.28.3-28.3
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    • 2011
  • Halo coronal mass ejections (HCMEs) are mainly responsible for the most severe geomagnetic storms. To minimize the projection effect of the HCMEs observed by coronagraphs, several cone models have been suggested. These models allow us to determine the geometrical and kinematic parameters of HCMEs : radial speed, source location, angular width, and the angle between the central axis of the cone and the plane of the sky. In this study, we compare these parameters form two representative cone models (the ice-cream cone model and the asymmetric cone model) using well-observed HCMEs from 2001 to 2002. And we obtain the root mean square error (rms error) between observed projection speeds and calculated projection speeds for both cone models. It is found that the average rms speed error (89 km/s) of the asymmetric cone model is a little smaller than that (107 km/s) of the ice-cream cone models, implying that the radial speeds from both models are reasonably estimated. We also find that the radial speeds obtained from two models are similar to each other with the correlation coefficient of about 0.8.

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