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통합검색

통합검색

한국우주과학회지

1984년 ~ 2018년까지 1,108 건한국우주과학회지를 계간으로 확인하실 수 있습니다.

  • The Korean Space Science Society (The Korean Astronomical Society)
  • 계간 (Quarterly)
  • ISSN : 1225-052X (ISSN : 1225-052X)
  • DB구축현황 : 1,108건 (DB Construction : 1,108 Articles)
안내사항
총 게시글 1,108 페이지 1/111
1
  • Oh, Daehyeon
  • Journal of astronomy and space sciences
  • 35, n.3
  • pp.175-183
  • 2018
  • 원문 바로보기
Many recent satellites have mission periods longer than 10 years; thus, satellite-based local space weather monitoring is becoming more important than ever. This article describes the instruments and data applications of the Korea Space wEather Monitor (KSEM), which is a space weather payload of the GeoKompsat-2A (GK-2A) geostationary satellite. The KSEM payload consists of energetic particle detectors, magnetometers, and a satellite charging monitor. KSEM will provide accurate measurements of the energetic particle flux and three-axis magnetic field, which are the most essential elements of space weather events, and use sensors and external data such as GOES and DSCOVR to provide five essential space weather products. The longitude of GK-2A is $128.2^{\circ}E$ , while those of the GOES satellite series are $75^{\circ}W$ and $135^{\circ}W$ . Multi-satellite measurements of a wide distribution of geostationary equatorial orbits by KSEM/GK-2A and other satellites will enable the development, improvement, and verification of new space weather forecasting models. KSEM employs a service-oriented magnetometer designed by ESA to reduce magnetic noise from the satellite in real time with a very short boom (1 m), which demonstrates that a satellite-based magnetometer can be made simpler and more convenient without losing any performance.
2
  • Kwon, Hyuck-Jin
  • Journal of astronomy and space sciences
  • 35, n.3
  • pp.185-193
  • 2018
  • 원문 바로보기
Jang Bogo Station (JBS), the second Korean Antarctic research station, was established in Terra Nova Bay, Antarctica ( $74.62^{\circ}S$ $164.22^{\circ}E$ ) in February 2014 in order to expand the Korea Polar Research Institute (KOPRI) research capabilities. One of the main research areas at JBS is space environmental research. The goal of the research is to better understand the general characteristics of the polar region ionosphere and thermosphere and their responses to solar wind and the magnetosphere. Ground-based observations at JBS for upper atmospheric wind and temperature measurements using the Fabry-Perot Interferometer (FPI) began in March 2014. Ionospheric radar (VIPIR) measurements have been collected since 2015 to monitor the state of the polar ionosphere for electron density height profiles, horizontal density gradients, and ion drifts. To investigate the magnetosphere and geomagnetic field variations, a search-coil magnetometer and vector magnetometer were installed in 2017 and 2018, respectively. Since JBS is positioned in an ideal location for auroral observations, we installed an auroral all-sky imager with a color sensor in January 2018 to study substorms as well as auroras. In addition to these observations, we are also operating a proton auroral imager, airglow imager, global positioning system total electron content (GPS TEC)/scintillation monitor, and neutron monitor in collaboration with other institutes. In this article, we briefly introduce the observational activities performed at JBS and the preliminary results of these observations.
3
  • Yu, Young Sam
  • Journal of astronomy and space sciences
  • 35, n.3
  • pp.201-210
  • 2018
  • 원문 바로보기
The characterization of detectors installed in space- and ground-based instruments is important to evaluate the system performance. We report the development of a detector performance test system for astronomical applications using the Andor iKon M CCD camera. The performance test system consists of a light source, monochromator, integrating sphere, and power meters. We adopted the Czerny-Tuner monochromator with three ruled gratings and one mirror, which covers a spectral range of 200-9,000 nm with a spectral resolution of ~1 nm in the visible region. Various detector characteristics, such as the quantum efficiency, sensitivity, and noise, can be measured in wide wavelength ranges from the visible to mid-infrared regions. We evaluated the Korea Astronomy and Space Science Institute (KASI) detector performance test system by using the performance verification of the Andor iKon-M CCD camera. The test procedure includes measurements of the conversion gain ( $2.86e^-/ADU$ ), full well capacity ( $130K\;e^-$ ), nonlinearity, and pixel defects. We also estimated the read noise, dark current, and quantum efficiency as a function of the temperature. The lowest measured read noise is $12e^-$ . The dark current at 223 K was determined to be $7e^-/s/pix$ and its doubling temperature is $5.3^{\circ}C{\pm}0.2^{\circ}C$ at an activation energy of 0.6 eV. The maximum quantum efficiency at 223 K was estimated to be $93%{\pm}2%$ . We proved that the quantum efficiency is sensitive to the operating temperature. It varies up to 5 % in the visible region, while the variation increases to 30 % in the near-infrared region. Based on the comparison of our results with the test report by the vendor, we conclude that our performance test results are consistent with those from the vendor considering the test environment. We also confirmed that the KASI detector performance test system is reliable and our measurement method and analysis are accurate.
4
  • Jeong, Se-Heon
  • Journal of astronomy and space sciences
  • 35, n.3
  • pp.143-149
  • 2018
  • 원문 바로보기
The ionosphere has been monitored by ionosondes for over five decades since the 1960s in Korea. An ionosonde typically produces an ionogram that displays radio echoes in the frequency-range plane. The trace of echoes in the plane can be read either manually or automatically to derive useful ionospheric parameters such as foF2 (peak frequency of the F2 layer) and hmF2 (peak height of the F2 layer). Monitoring of the ionosphere should be routinely performed in a given time cadence, and thus, automatic scaling of an ionogram is generally executed to obtain ionospheric parameters. However, an auto-scaling program can generate undesirable results that significantly misrepresent the ionosphere. In order to verify the degree of misrepresentation by an auto-scaling program, we performed manual scaling of all 35,136 ionograms measured at Jeju ( $33.43^{\circ}N$ , $126.30^{\circ}E$ ) throughout 2012. We compared our manually scaled parameters (foF2 and hmF2) with auto-scaled parameters that were obtained via the ARTIST5002 program. We classified five cases in terms of the erroneous scaling performed by the program. The results of the comparison indicate that the average differences with respect to foF2 and hmF2 between the two methods approximately correspond to 0.03 MHz and 4.1 km, respectively with corresponding standard deviations of 0.12 MHz and 9.58 km. Overall, 36 % of the auto-scaled results differ from the manually scaled results by the first decimal number. Therefore, future studies should be aware of the quality of auto-scaled parameters obtained via ARTIST5002. Hence, the results of the study recommend the use of manually scaled parameters (if available) for any serious applications.
5
  • Lee, Jongwoo
  • Journal of astronomy and space sciences
  • 35, n.3
  • pp.163-173
  • 2018
  • 원문 바로보기
This paper presents relative navigation using intermittent laser-based measurement data for spacecraft flying formation that consist of two spacecrafts; namely, chief and deputy spacecrafts. The measurement data consists of the relative distance measured by a femtosecond laser, and the relative angles between the two spacecrafts. The filtering algorithms used for the relative navigation are the extended Kalman filter (EKF), unscented Kalman filter (UKF), and least squares recursive filter (LSRF). Numerical simulations reveal that the relative navigation performances of the EKF- and UKF-based relative navigation algorithms decrease in accuracy as the measurement outage period increases. However, the relative navigation performance of the UKF-based algorithm is 95 % more accurate than that of the EKF-based algorithm when the measurement outage period is 80 sec. Although the relative navigation performance of the LSRF-based relative navigation algorithm is 94 % and 370 % less accurate than those of the EKF- and UKF-based navigation algorithms, respectively, when the measurement outage period is 5 sec; the navigation error varies within a range of 4 %, even though the measurement outage period is increased. The results of this study can be applied to the design of a relative navigation strategy using the developed algorithms with laser-based measurements for spacecraft formation flying.
6
  • Park, Woochan
  • Journal of astronomy and space sciences
  • 35, n.3
  • pp.133-141
  • 2018
  • 원문 바로보기
We report on our Galactic plane searches for magnetars in the archival Chandra X-ray Observatory (CXO) data. We summarize the properties of known magnetars and use them to establish a procedure for magnetar searches. The procedure includes four steps: source finding, spectral characterization, optical counterpart checks, and period searches. We searched 1,282 archival CXO observations, found 32,838 X-ray sources, and selected 25 intriguing candidates using the developed procedure. Although we do not firmly identify a magnetar among them, we significantly reduced the number of targets in future magnetar searches to be done with better X-ray telescopes.
7
  • Muraki, Yasushi
  • Journal of astronomy and space sciences
  • 35, n.2
  • pp.75-81
  • 2018
  • 원문 바로보기
Solar activity has an important impact not only on the intensity of cosmic rays but also on the environment of Earth. In the present paper, a coupled oscillator model is proposed to explain solar activity. This model can be used to naturally reduce the 89-year Gleissberg cycle. Furthermore, as an application of the coupled oscillator model, we herein attempt to apply the proposed model to El $Ni{\tilde{n}}o$ -southern oscillation (ENSO). As a result, the 22-year oscillation of the Pacific Ocean is naturally explained. Finally, we search for a possible explanation for coupled oscillators in actual solar activity.
8
  • Lee, Young-Sook
  • Journal of astronomy and space sciences
  • 35, n.2
  • pp.83-92
  • 2018
  • 원문 바로보기
The summer polar lower thermosphere (90-100 km) has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE). We report the observation of meteor trail with nearly horizontal transit at high speed (20-50 km/s), and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to 'head echoes', with travel speeds from 20 - 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.
9
  • Lee, Seongsuk
  • Journal of astronomy and space sciences
  • 35, n.2
  • pp.105-109
  • 2018
  • 원문 바로보기
El $Ni{\tilde{n}}o$ is the largest fluctuation in the climate system, and it can lead to effects influencing humans all over the world. An El $Ni{\tilde{n}}o$ occurs when sea surface temperatures in the central and eastern tropical Pacific Ocean become substantially higher than average. We investigated the change in sea surface temperature in the Pacific Ocean during the El $Ni{\tilde{n}}o$ period of 2015 and 2016 using the advanced very-high-resolution radiometer (AVHRR) of NOAA Satellites. We calculated anomalies of the Pacific equatorial sea surface temperature for the normal period of 1981-2010 to identify the variation of the 2015 El $Ni{\tilde{n}}o$ and warm water area. Generally, the warm water in the western tropical Pacific Ocean shifts eastward along the equator toward the coast of South America during an El $Ni{\tilde{n}}o$ period. However, we identified an additional warm water region in the $Ni{\tilde{n}}o$ 1+2 and Peru coastal area. This indicates that there are other factors that increase the sea surface temperature. In the future, we will study the heat coming from the bottom of the sea to understand the origin of the heat transport of the Pacific Ocean.
10
  • Yeo, Insung
  • Journal of astronomy and space sciences
  • 35, n.2
  • pp.67-74
  • 2018
  • 원문 바로보기
Higgs boson enables the Standard Model (SM) to be established. However, we do not know much about dark matter which occupies approximately six times of the SM particles in universe besides having mass. The interactions of dark matter is much weaker than that of the SM. Further, its mass range is very wide, from the order of eV to PeV. Therefore, many experiments have contributed to search for dark matter by indirect, direct and accelerator research. This paper reviews researches on dark matter using accelerator, especially the $e^+e^-$ collider, from the viewpoint of experimental high energy physicists.