• 제목/요약/키워드: solar observation

검색결과 371건 처리시간 0.028초

Observations of Light bridge jets using the New Solar Telescope

  • Lim, Eun-Kyung
    • 천문학회보
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    • 제42권2호
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    • pp.83.2-83.2
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    • 2017
  • We report observations of light bridge (LB) jets taken with the New Solar Telescope. Jets as dark, fine threads occurred lined along both edges of a LB of a sunspot, which is a bright and elongated structure that divides a sunspot's umbra into two or more parts. This LB jets are observed for about three hours with $H{\alpha}$ filtergraph at ${\pm}0.4{\AA}$, ${\pm}0.8{\AA}$ from the line center, TiO filtergraph, and near infra-red imaging spectropolarimeter (NIRIS). High resolution $H{\alpha}$ data revealed that subsequent ejection of LB jets were associated with subsequent brightening along the edge of the LB. Also, this subsequent brightening was spatially correlated with both photospheric flow and magnetic field change detected from the TiO and NIRIS data, respectively. Preliminary results of LB jet observation and discussions on its formation mechanism will be presented.

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저일사강도에서 MPPT를 동작시키기 위한 알고리즘 연구 (A Study of MPPT Algorithm for Low Insolation)

  • 유권중;정영석;김기현;최주엽
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제51권3호
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    • pp.142-149
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    • 2002
  • As is well-known, the maximum power point (MPP) of PV power generation system depends on array temperature and solar insolation, it is necessary to track MPP of solar array all the time. Among various MPP control algorithms, the constant voltage control method, the perturbation and observation (P&O) method and the incremental conductance method (IncCond) have drawn many attractions due to the usefulness of each system. In this parer, the effectiveness of above mentioned three different control algorithms are thoroughly investigated via simulations and preposed efficiency evaluation method on experiment. Both the steady-state and transient characteristics of each control algorithms along with measured efficiency are analyzed, respectively. Finally, a novel MPPT control algorithm combining the constant voltage control and IncCond method for low insolation condition is proposed to improve efficiency of the 3KW PV power generation system.

새로운 MPPT 알고리듬의 시뮬레이션 및 실험을 통한 실증 연구 (A Novel Two-Mode MPPT Control Algorithm Based on Comparative Study of Existing Algorithms)

  • 최주엽;유권종;정영석
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.207-212
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    • 2002
  • As is well-known, the maximum power point(MPP) of PV power generation system depends on array temperature and solar insolation, it is necessary to track MPP of solar array all the time. Among various MPP control algorithms, the constant voltage control method, the perturbation and observation(P&O) method and the incremental conductance method(IncCond) have drawn many attractions due to the usefulness of each system. In this paper, the effectiveness of above mentioned three different control algorithms are thoroughly investigated via simulations and proposed efficiency evaluation method on experiment. Both the steady-state and transient characteristics of each control algorithms along with measured efficiency are analyzed, respectively. Finally, a novel MPPT control algorithm combining the constant voltage control and IncCond method for low insolation condition is proposed to improve efficiency of the 3KW PV power generation system.

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ERROR ANALYSIS FOR GOCI RADIOMETRIC CALIBRATION

  • Kang, Gm-Sil;Youn, Heong-Sik
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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    • pp.187-190
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    • 2007
  • The Geostationary Ocean Color Imager (GOCI) is under development to provide a monitoring of ocean-color around the Korean Peninsula from geostationary platforms. It is planned to be loaded on Communication, Ocean, and Meteorological Satellite (COMS) of Korea. The GOCI has been designed to provide multi-spectral data to detect, monitor, quantify, and predict short term changes of coastal ocean environment for marine science research and application purpose. The target area of GOCI observation covers sea area around the Korean Peninsula. Based on the nonlinear radiometric model, the GOCI calibration method has been derived. The nonlinear radiometric model for GOCI will be validated through ground test. The GOCI radiometric calibration is based on on-board calibration devices; solar diffuser, DAMD (Diffuser Aging Monitoring Device). In this paper, the GOCI radiometric error propagation is analyzed. The radiometric model error due to the dark current nonlinearity is analyzed as a systematic error. Also the offset correction error due to gain/offset instability is considered. The radiometric accuracy depends mainly on the ground characterization accuracies of solar diffuser and DAMD.

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CHARACTERISTICS AND PERFORMANCE OF A FAST CCD CAMERA: DALSTA IM30P

  • SEO YOUNG-MIN;PARK KI-WOONG;CHAE JONGCRUL
    • 천문학회지
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    • 제37권4호
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    • pp.185-191
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    • 2004
  • We have been developing a solar observing system based on a fast CCD camera 1M30P made by the DALSA company. Here we examine and present the characteristics and performance of the camera. For this we have analyzed a number of images of a flat wall illuminated by a constant light source. As a result we found that in the default operating mode 1) the mean bias level is 49 ADU/pix, 2) the mean dark current is about 8 ADU /s/pix, 3) the readout noise is 1.3 ADU, and 4) the gain is about 42 electrons/ ADU. The CCD detector is found to have a linearity with a deviation smaller than $6\%$, and a uniform sensitivity better than $1\%$. These parameters will be used as basic inputs in the analysis of data to be taken by the camera.

하절기 도시 유형별 기상요소 비교 -대구광역시와 인근 4개 지역을 중심으로- (Comparison of Meteorological Elements by Type of City during Summer Season - Focus on the Daegu Metropolitan City and the Surrounding Four Regions -)

  • 최동호;이부용;정형세
    • 한국태양에너지학회 논문집
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    • 제34권6호
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    • pp.111-122
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    • 2014
  • The purpose of this study is to understand relation of meteorological elements of air temperature, relative humidity and vapor pressure of four cities with Daegu. The followings are main results from this study. 1) There is very high correlation of meteorological elements according to distance between city and city. 2) In case of seaside town at Pohang, there were little changes than other cities for temperature, humidity and vapor pressure. 3) It was analysed stable and similar diurnal variation in water vapor pressure than air temperature and relative humidity at all observation site.

Two-Mode MPPT 알고리즘 연구 및 효율평가법 (A Study on the Two-Mode MPPT Control Algorithm and Efficiency Evaluation Method)

  • 유권종;김기현;정영석;김영석
    • 한국태양에너지학회 논문집
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    • 제21권1호
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    • pp.11-20
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    • 2001
  • In this paper described common MPPT(Maximum Power Point Tracking) control algorithm; Constant Voltage Control, P&O(Perturbation and Observation), IncCond(Incremental Conductance), and investigated it's efficiency. Through simulation and efficiency evaluation, analyze the steady/transient states characteristics and efficiency of control algorithms respectively. Also, To high-efficiency proposed Two-mode MPPT control for improve on the existing control algorithm. Moreover, this paper suggested a topology for MPPT measuring efficiency and a method of examination.

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Comparison between Simulations and Observations Focused on Upflow Area in Active Region

  • 이환희;;안준모;강지혜
    • 천문학회보
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    • 제37권2호
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    • pp.131.1-131.1
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    • 2012
  • We use three-dimensional magnetohydrodynamic (MHD) simulations of flux emergence from solar subsurface to corona. In our previous work, we reported the relation between magnetic-field configuration and the flux expansion factor. Following these results, we investigate where an upflow is generated in an active region and how its location is related to the flux expansion factor. We also derive physical quantities of a real active region from observation data provided by Nobeyama Radioheliograph (NoRH), X-Ray Telescope (XRT), and Extreme Ultraviolet Imaging Spectrometer (EIS) onboard Hinode. These physical quantities are plasma density, temperature and flow. By comparing the simulation result and observational one, we will discuss the properties of the location producing a solar wind.

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Predictability of the f/g time series

  • 조일현;김연한;조경석;박영득
    • 천문학회보
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    • 제36권1호
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    • pp.40.1-40.1
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    • 2011
  • Large solar flares are associated with various aspects of space weather effects. Numerous attempts have been made to predict when the solar flare will be occurred mainly based on the configuration of the magnetic field of its flaring site. We analyze the time series of f/g which indicates a representative measure of the sunspot complexity to see whether it shows a possibility to be predicted without huge amounts of observation. Two kinds of analysis results are presented. One is from its power spectrum giving that there's no significantly persistent periodicity within a few days. Its de-trended fluctuation shows the Hurst exponent larger than 0.5 implying that the f/g time series has a long-term memory in time scales less than 10 days.

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A BRIGHT RIM OF SOLAR FILAMENT OBSERVED BY USING FISS

  • 양희수;채종철;송동욱
    • 천문학회보
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    • 제36권1호
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    • pp.38.1-38.1
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    • 2011
  • Bright rims are one of the most unknown part of a filament nowadays. Many models tried to explain the environments, but there is no commonly acceptable model. Many survey observations have been performed to find various characteristics of the bright rim statistically, but there was only one spectroscopic observation to understand phenomena of the bright rim. We observed a bright rim on June 25, 2010 using FISS installed in NST, Big Bear Solar observatory. FISS can obtain a couple of wavebands data simultaneously with short time cadence and fine resolution(~ 0.1", expected) with Adaptive Optics. By applying the cloud model, we found source function, optical thickness, temperature and non-thermal velocity of the region from the spectra of Ha and CaII 8542 lines. We discuss the physical implication of these measurements on the nature of bright rims of filaments.

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