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1984년 ~ 2025년까지 1,255 건의 한국우주과학회지를 계간으로 확인하실 수 있습니다.
- The Korean Space Science Society (The Korean Astronomical Society)
- 계간 (Quarterly)
- ISSN : 1225-052x (ISSN : 1225-052x)
1225-052x
- DB구축현황 : 1,255건 (DB Construction : 1,255 Articles)
총 게시글 1,255건
페이지 35/126
341
- Hwang, Junga
- Journal of astronomy and space sciences
- 31, n.1
- pp.25-31
- 2014
- 원문 바로보기
There has been a rapid increase of the concern on the space radiation effect on pilots, crew and passengers at the commercial aircraft altitude (~ 10 km) recently. It is because domestic airline companies, Korean Air and Asiana Airlines have just begun operating the polar routes over the North Pole since 2006 and 2009 respectively. CARI-6 and CARI-6M are commonly used space radiation estimation programs which are provided officially by the U.S. federal aviation administration (FAA). In this paper, the route doses and the annual radiation doses for Korean pilots and cabin crew were estimated by using CARI-6M based on 2012 flight records. Also the modeling concept was developed for our own space radiation estimation program which is composed of GEANT4 and NRLMSIS00 models. The GEANT4 model is used to trace the incident particle transports in the atmosphere and the NRLMSIS00 model is used to get the background atmospheric densities of various neutral atoms at the aircraft altitude. Also presented are the results of simple integration tests of those models and the plan to include the space weather variations through the solar proton event (SPE) prediction model such as UMASEP and the galactic cosmic ray (GCR) prediction model such as Badhwar-O'Neill 2010.
342
- Jeong, Woong-Seob
- Journal of astronomy and space sciences
- 31, n.1
- pp.83-90
- 2014
- 원문 바로보기
The NISS onboard NEXTSat-1 is being developed by Korea astronomy and space science institute (KASI). For the study of the cosmic star formation history, the NISS performs the imaging spectroscopic observation in the near-infrared range for nearby galaxies, low background regions, star-forming regions and so on. It is designed to cover a wide field of view (<TEX>$2{\times}2$</TEX> deg) and a wide wavelength range from 0.95 to <TEX>$3.8{\mu}m$</TEX> by using linear variable filters. In order to reduce the thermal noise, the telescope and the infrared sensor are cooled down to 200 K and 80 K, respectively. Evading a stray light outside the field of view and making the most use of limited space, the NISS adopts the off-axis reflective optical system. The primary and the secondary mirrors, the opto-mechanical part and the mechanical structure are designed to be made of aluminum material. It reduces the degradation of optical performance due to a thermal variation. This paper presents the study on the conceptual design of the NISS.
343
- Eom, We-Sub
- Journal of astronomy and space sciences
- 31, n.4
- pp.347-351
- 2014
- 원문 바로보기
Planetary exploration rovers are likely to make a trip on a winding and sloping road of irregular surfaces to the destination in order to accomplish scientific missions. One of the key technologies for rovers is a suspension for traveling and performing exploration missions; the suspension is an essential area of technology for a stable movement of a rover. In this study, an 8-wheel suspension is designed to enable efficient climbing of slopes on a passage to the destination. For the two front wheels among the eight wheels, the moment at the pivot connecting two wheels is derived when the distance between the wheels and the torque of wheels are same. A test experiment was performed to compare the magnitude of moment according to the change in tilt angle and the position of the pivot. Finally, a suspension design considering the position of the pivot was proposed to enhance the hill-climbing performance.
344
- Lee, Junhyun
- Journal of astronomy and space sciences
- 31, n.4
- pp.311-315
- 2014
- 원문 바로보기
In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.
345
- Shin, Goo-Hwan
- Journal of astronomy and space sciences
- 31, n.3
- pp.235-240
- 2014
- 원문 바로보기
The communications link in a space program is a crucial point for upgrading its performance by handling data between spacecraft bus and payloads, because spacecraft's missions are related to the data handling mechanism using communications ports such as a controlled area network bus (CAN Bus) and a universal asynchronous receiver and transmitter (UART). The NEXTSat-1 has a lot of communications ports for performing science and technology missions. However, the top level system requirements for the NEXTSat-1 are mass and volume limitations. Normally, the communications for units shall be conducted by using point to point link which require more mass and volume to interconnect. Thus, our approach for the novel communications link in the NEXTSat-1 program is to use CAN and serializer and deserializer low voltage differential signal (SerDesLVDS) to meet the system requirements of mass and volume. The CAN Bus and SerDesLVDS were confirmed by using already defined communications link for our missions in the NEXTSat-1 program and the analysis results were reported in this study in view of data flow and size analysis.
346
- Jun, Chae-Woo
- Journal of astronomy and space sciences
- 30, n.1
- pp.25-32
- 2013
- 원문 바로보기
We statistically investigated the properties of low-latitude Pi2 pulsations using Bohyun (BOH, Mlat = <TEX>$29.8^{\circ}$</TEX>, L = 1.35) ground magnetometer data in 2008. For this 1-year interval, 582 Pi2 events were identified when BOH was in the nightside from 1800 to 0600 local times. We found the following Pi2 characteristics. (1) The occurrence distribution of Pi2s is relatively constant in local times. (2) The Pi2 frequency varies in local times. That is, Pi2 pulsations in postmidnight sector had higher frequency than in premidnight sector. (3) Pi2 power in premidnight sector is stronger than in postmidnight sector. (4) Pi2 frequency has positive correlation with solar wind speed and AE index. (5) Pi2 power has not a clear correlation with solar wind parameters. This indicates that Pi2 power is not controlled by external sources. (6) It is found that the most probable-time between Pi2 onsets is <TEX>${\Delta}t$</TEX> ~ 37.5 min: This is interpreted to be the period between Pi2 pulsations when they occur cyclically. We suggest that <TEX>${\Delta}t$</TEX> ~ 37.5 min is the occurrence rate of reconnection of open field lines in the tail lobe.
347
- Kwak, Younghee
- Journal of astronomy and space sciences
- 30, n.4
- pp.315-320
- 2013
- 원문 바로보기
Space geodetic techniques can be used to obtain precise shape and rotation information of the Earth. To achieve this, the representative combination solution of each space geodetic technique has to be produced, and then those solutions need to be combined. In this study, the representative combination solution of very long baseline interferometry (VLBI), which is one of the space geodetic techniques, was produced, and the variations in the position coordinate of each station during 7 years were analyzed. Products from five analysis centers of the International VLBI Service for Geodesy and Astrometry (IVS) were used as the input data, and Bernese 5.0, which is the global navigation satellite system (GNSS) data processing software, was used. The analysis of the coordinate time series for the 43 VLBI stations indicated that the latitude component error was about 15.6 mm, the longitude component error was about 37.7 mm, and the height component error was about 30.9 mm, with respect to the reference frame, International Terrestrial Reference Frame 2008 (ITRF2008). The velocity vector of the 42 stations excluding the YEBES station showed a magnitude difference of 7.3 mm/yr (30.2%) and a direction difference of <TEX>$13.8^{\circ}$</TEX> (3.8%), with respect to ITRF2008. Among these, the 10 stations in Europe showed a magnitude difference of 7.8 mm/yr (30.3%) and a direction difference of <TEX>$3.7^{\circ}$</TEX> (1.0%), while the 14 stations in North America showed a magnitude difference of 2.7 mm/yr (15.8%) and a direction difference of <TEX>$10.3^{\circ}$</TEX> (2.9%).
348
- Seo, Kyoung-Ae
- Journal of astronomy and space sciences
- 30, n.2
- pp.87-90
- 2013
- 원문 바로보기
We have investigated the X-ray emission from the shock-heated plasma of the Galactic supernova remnant Kesteven 69 with XMM-Newton. Assuming the plasma is at collisional ionization equilibrium, a plasma temperature and a column absorption are found to be kT ~ 0.62 keV and <TEX>$N_H{\sim}2.85{\times}10^{22}\;cm^{-2}$</TEX> respectively by imaging spectroscopy. Together with the deduced emission measure, we place constraints on its Sedov parameters.
349
- Oh, Eunsong
- Journal of astronomy and space sciences
- 30, n.4
- pp.321-326
- 2013
- 원문 바로보기
The modulation transfer function (MTF) is a widely used indicator in assessments of remote-sensing image quality. This MTF method is also used to restore information to a standard value to compensate for image degradation caused by atmospheric or satellite jitter effects. In this study, we evaluated MTF values as an image quality indicator for the Geostationary Ocean Color Imager (GOCI). GOCI was launched in 2010 to monitor the ocean and coastal areas of the Korean peninsula. We evaluated in-orbit MTF value based on the GOCI image having a 500-m spatial resolution in the first time. The pulse method was selected to estimate a point spread function (PSF) with an optimal natural target such as a Seamangeum Seawall. Finally, image restoration was performed with a Wiener filter (WF) to calculate the PSF value required for the optimal regularization parameter. After application of the WF to the target image, MTF value is improved 35.06%, and the compensated image shows more sharpness comparing with the original image.
350
- Ko, Kyeongyeon
- Journal of astronomy and space sciences
- 30, n.4
- pp.307-314
- 2013
- 원문 바로보기
Infrared optical systems are operated at low temperature and vacuum (LT-V) condition, whereas the assembly and alignment are performed at room temperature and non-vacuum (RT-NV) condition. The differences in temperature and pressure between assembly/alignment environments and operation environment change the physical characteristics of optical and opto-mechanical parts (e.g., thickness, height, length, curvature, and refractive index), and the resultant optical performance changes accordingly. In this study, using input relay optics (IO), among the components of the Immersion GRating INfrared Spectrograph (IGRINS) which is an infrared spectrograph, a simulation based on the physical information of this optical system and an actual experiment were performed; and optical performances in the RT-NV, RT-V, and LT-V environments were predicted with an accuracy of <TEX>$0.014{\pm}0.007{\lambda}$</TEX> rms WFE, by developing an adaptive fitting line. The developed adaptive fitting line can quantitatively control assembly and alignment processes below <TEX>${\lambda}/70$</TEX> rms WFE. Therefore, it is expected that the subsequent processes of assembly, alignment, and performance analysis could not be repeated.