• Atmosphere
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• v.17 no.2
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• pp.115-123
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• 2007

The present study uses the GOES IR brightness temperature to examine the temporal and spatial variability of cloud activity over the region $25^{\circ}N-45^{\circ}N$, $105^{\circ}E-135^{\circ}E$ and analyzes the coherence of eastern Asian summer season rainfall in Weather Research and Forecast (WRF) model. Time-longitude diagram of the time period from June to July 2005 shows a signal of eastward propagation in the WRF model and convective index derived from GOES IR data. The rain streaks in time-latitude diagram reveal coherence during the experiment period. Diurnal and synoptic scales are evident in the power spectrum of the time series of convective index and WRF rainfall. The diurnal cycle of early morning rainfall in the WRF model agrees with GOES IR data in the Korean Peninsula, but the afternoon convection observed by satellite observation in China is not consistent with the WRF rainfall which is represented at the dawn. Although there are errors in strength and timing of convection, the model predicts a coherent tendency of rainfall occurrence during summer season.

• Journal of Astronomy and Space Sciences
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• v.30 no.3
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• pp.169-174
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• 2013

BOH magnetometer was installed at Mt. Bohyun in 2007 and has provided continuous dataset for 3-axis geomagnetic field over the South Korea. We have calculated real-time K-index based on BOH magnetic field data using well-known FMI method. Local K-index is calculated eight times a day, per every three hours. To calculate K-index, it is critical to get the Quiet Day Curve (QDC). For QDC calculation, we take the previous one month's average of H-component. In this paper, we compared four geomagnetic stations' magnetic field data over South Korea and Japan and K-indices of each stations; Bohyun, Gangneung, Jeju, and Kakioka for two years data, 2011-2012. To investigate the difference depending on the latitude, longitude and local time in more detail, we compare K-index on International Quiet Days (IQDs) and International Disturbed Days (IDDs). As a result, we report the correlation between local K-indices are higher than those between Kp and local K-indices, and the correlation is much better after sunset than after sunrise. As the geomagnetic activity becomes stronger, the correlation between the local K-indices and global Kp-index become higher.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.29-36
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• 2012

The existing solar tracking sensor for 2 axial control system to trace latitude and longitude is made of four phototransistor. The phototransistor-making is difficult and it's manufacturing is more high-priced than a wide use phototransistor because they have to the same characteristics of each phototransistor output signal. This paper described the algorithm for supplement these weakness. The algorithm applied to signal normalizing method and vector decomposition law. The deviations of each a wide use phototransistor output signal are resolved by signal normalizing method and it is able to make a solar tracking sensor using three phototransistor by vector decomposition law. Therefore, in this paper, it is reduced the number of phototransistor that is composed of solar tracking sensor and possible to use a wide use phototransistor by the proposed algorithm.

• Journal of the Korean Solar Energy Society
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• v.37 no.1
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• pp.39-45
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• 2017

This paper presents the effect of solar collectors on the performance of solar tracking daylighting systems. A series of measurements were made for two different types of solar collectors mounted on double axis solar trackers: Parabolic dish concentrator and Fresnel Lens. Indoor light levels were measured at different locations of an office space (longitude: 126.33 E, latitude 33.45 N) as photo sensors were placed on a task plane 80 cm above the floor. To accurately monitor the applicability of the systems, measurements were performed under clear and overcast sky conditions with the roll-screen (on the south window) in the down position. Comparing the illuminance data, the system with Fresnel lens outperformed that of parabolic dish concentrator. On clear days, the former delivered the light levels of 400~600 lux on the task plane whereas the latter recorded 100~200 lux. Depending on the amount of cloud cover, on overcast days, illuminance readings fluctuated to some extent.

• Publications of The Korean Astronomical Society
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• v.15 no.1
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• pp.31-34
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• 2000

We determined the precise three dimensional WGS84 Coordinates and the sea level height of Seoul Radio Astronomy Observatory (SRAO). In this study, we performed the simultaneous GPS observations at SRAO and Seoul GPS Reference Station(SGRS) of Korea Astronomy Observatory(KAO) for 3.5 hours from 17KST on October 27, 1999. We employed two different antennas, i.e., chokering antenna at SGRS of KAO and L1/L2 compact with groundplane antenna at SRAO. But we employed same type of receivers, i.e., Trimble 4000SSI at both observing places. The observed data were processed by GPSURVEY 2.30 software of Trimble with L1/L2 ION Free technique and broadcasting ephemeris of GPS Satellites because of very short baseline between SGRS of KAO and SRAO. We determined WGS84 latitude, longitude, height and the sea level height of SRAO with $37^{\circ}\;27'\;15.'\;6846N\pm0.'\;0004,\;126^{\circ}\;57'\;19.'\;0727E\pm0.'\;0002,\;204.89m\pm0.02m,\;181.38m\pm0.17m$, respectively.

• Journal of The Korean Astronomical Society
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• v.28 no.1
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• pp.89-95
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• 1995

We examined a total of 166 images of $3.5{\mu}m\;H_3^+$ emission in the auroral regions of Jupiter observed with the Protocam on IRTF in 1991 and 1992, and found that 30 images contain a clearly isolated small emission patch in the vicinity of the northern auroral regions. Two different time sequences of the images show the small patches at the dusk limb in the range of System III longitudes from $270^{\circ}\;through\;0^{\circ}\;to\;90^{circ}$. The small patches in one sequence of the images, which were taken at 10 phase between $240^{\circ}\;and\;260^{\circ}$, may be related to the 10 flux tube, similarly suggested by Connerney et al. (1993). However, the small patches in the other sequence are separated from Io as much as $80^{\circ}$ in longitude. The positions of the small patches in both sequences are deviated equatorward from the 10 footprint oval by $5^{\circ}-8^{\circ}$ latitude in the longitudinal range of $270^{\circ}-360^{\circ}$. A significant modification is required in current Jovian magnetic field models near the Jupiter's surface if the small patches are produced at the foot of the 10 flux tube.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.33-33
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• 2013

We are developing empirical space weather (solar flare, solar proton event, and geomagnetic storm) forecast models based on solar data. In this talk we will review our main results and recent progress. First, we have examined solar flare (R) occurrence probability depending on sunspot McIntosh classification, its area, and its area change. We find that sunspot area and its increase (a proxy of flux emergence) greatly enhance solar flare occurrence rates for several sunspot classes. Second, a solar proton event (S) forecast model depending on flare parameters (flare strength, duration, and longitude) as well as CME parameters (speed and angular width) has been developed. We find that solar proton event probability strongly depends on these parameters and CME speed is well correlated with solar proton flux for disk events. Third, we have developed an empirical storm (G) forecast model to predict probability and strength of a storm using halo CME - Dst storm data. For this we use storm probability maps depending on CME parameters such as speed, location, and earthward direction. We are also looking for geoeffective CME parameters such as cone model parameters and magnetic field orientation. We find that all superstorms (less than -200 nT) occurred in the western hemisphere with southward field orientations. We have a plan to set up a storm forecast method with a three-stage approach, which will make a prediction within four hours after the solar coronagraph data become available. We expect that this study will enable us to forecast the onset and strength of a geomagnetic storm a few days in advance using only CME parameters and the WSA-ENLIL model. Finally, we discuss several ongoing works for space weather applications.

• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.294-299
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• 2006

Mt. Seokseong is located $37^{\circ}15'15'{\sim}37^{\circ}17'00'N$ in latitude at $127^{\circ}09'30'{\sim}127^{\circ}11'00'E$ in longitude in Yongin-si. As the result of cluster analysis, B site has 170 taxa of vascular plants, so it is the most abundant site in this area. And C site has 140 taxa of that, it is secondly abundant. But it has the highest similarity index (53.7%) between A site and B site. To construct natural resort for residents, it needed make thorned park just as hiking course, woods bathing site, aquatic place, pebble path, and natural garden path. And to protect ecological isolation of this area ecobridges must be constructed at Myeokjogogae and at Yongin Medical Hospital.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.569-572
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• 2002

Terra MODIS is one of the few space-borne sensors currently capable of acquiring radiometric data over the range of view angles. Institute of Industrial Science, University of Tokyo, has been receiving Terra MODIS data at Tokyo since May 2001 and Asian Institute of Technology at Bangkok since May 2001. They can cover whole East Asia and is expected to monitor environmental changes regularly such as deforestation, forest fires, floods and typhoon. Over eight hundred scenes have been archived in the storage system and they occupy 2 TB of disk space so far. In this study, MODIS data processing system on WWW is developed including following functions: spectral subset (250m, 500m, 1000m channels), radiometric correction to radiance, spatial subset of geocoded data as a rectangular area with latitude-longitude grid system in HDF format, generation of a quick look file in JPEG format. Users will be notified just after all the process have finished via e-mail. Using this system enables us to process MODIS data on WWW with a few input parameters and download the processed data by FTP access. An easy to use interface is expected to promote the use of MODIS data. This system is available via the Internet on the following URL from September 1 2002, "http : //webmodis.iis.u-tokyo.ac.jp/".

• Journal of Astronomy and Space Sciences
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• v.8 no.1
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• pp.99-113
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• 1991

We developed a software system called IODS(ISSA Orbit Determination System), which can predict the orbit of arbitary artificial satellite using the numerical method. For evaluating the orbit prediction accuracy of IODS, the orbital data predicted for the meteorological satellite NOAA-11 and the stationary satellite INTELSAT-V are intercompared with those tracked at the Central Bureau of Meterology and the Kum-San Satellite Communication Station. And the Perturbations affecting the orbit of these artificial satellites are quantitatively analyzed. The orbital variation and the eclipse phenomina due to the shadow are analyzed for a hypothetical geostationary satellite called KORSAT-1 which is assumed to be located in longitude $110^{circ}E$.