• Journal of Astronomy and Space Sciences
• /
• v.20 no.4
• /
• pp.283-298
• /
• 2003

The 2001 Leonid meteor storm has been observed all over the world, and its most intense flux since the last few decades has caused great interest among both laymen and experts. Especially, its maximum hours occurred at dawn hours of Nov. 19 in the east Asia, during which moonless clear night at the Mt. Bohyun allowed us near perfect condition of observation. Observation was carried out in the period of 01:00∼05:40(KST), which include the predicted maximum hours, with all-sky camera installed for upper atmospheric airglow research. Tn this paper we analyze 68 all-sky images obtained in this period, which contain records of 172 meteors. Utilizing the zenith hourly rate(ZHR) of 3000 and magnitude distribution index of 2, which were reported to International Meteor Organization by visible observers in the east Asia, we estimate the limiting magnitude of about 3 for meteors detected in our all-sky images. We then derive magnitudes of 83 meteors with clear pixel brightness outlines among the initially detected 172 meteors by comparing with neighbor standard stars. Angular velocities of meteors needed for computing their passing times over an all-sky image are expressed with a simple formula of an angle between a meteor head and the Leonid radiant point. The derived magnitudes of 83 meteors are in the range of -6∼-1 magnitude, and its distribution shows a maximum new -3mag. The derived magnitudes are much smaller than the limiting magnitude inferred from the comparison with the result of naked-eye observations. The difference may be due to the characteristic difference between nearly instantaneuous naked-eye observations and CCD observations with a long exposure. We redetermine magnitudes of the meteors by adjusting a meteor lasting time to be consistent with the naked-eye observations. The relative distribution of the redetermined magnitudes, which has a maximum at 0 mag., resembles that of the magnitudes determined with the in-principle method. The relative distribution is quite different from ones that decrease monotonically with decreasing magnitudes for meteors(1∼6) sensitive to naked-eye observations. We conclude from the magnitude distribution of our all-sky observation that meteors brighter than about 0 mag., appeared more frequently during the 2001 Leonid maximum hours. The frequent appearance of bright meteors has significantly important implication for meteor research. We noted, however, considerably large uncertainties in magnitudes determined only by comparing standard stars due to the unknown lasting time of meteors and the non-linear sensitivity of all-sky camera.

• Korean Journal of Environmental Biology
• /
• v.30 no.2
• /
• pp.90-97
• /
• 2012

Environmental characteristics and vegetation of the natural habitats of Eranthis byunsanensis B.Y. Sun were investigated in order to provide the basic data for conservation, restoration, and utilization of this Korean endemic plant. This study was conducted in Anyang, Byeonsan, Geoje, Gyeongju, Jeju, Ulsan and Yeosu. E. byunsanensis was distributed around the altitudes of 84~585 m with a slope degree of $10{\sim}20^{\circ}$, and mostly formed discontinuous populations in north-east part of valleys. Soil analysis showed the mean organic matter of 9.6% and a slightly acidic pH (mean pH of 4.9). The mean gravimetric water content was 16.5%. Correlation coefficients between environmental factors and community characteristics suggested that there was a positive correlation between slope degree and soil water content, between slope degree and soil pH, between soil organic matter and importance value, and between species richness or evenness and species diversity. The vascular plants from 59 quadrats of 7 habitats were identified into 144 taxa. A few species were dominants and similarly distributed in Byeonsan, Jeju, Ulsan and Yeosu. The highest species diversity was found in Geoje (1.43), while Anyang showed the lowest (0.87). Species evenness of Gyeongju and Jeju was bigger than 0.8, but that of Geoje was the lowest (0.59). Dominant species of woody plants in and around the 59 plots were represented by high frequency of Acer pictum subsp. mono, Carpinus cordata, Lindera obtusiloba, and Carpinus laxiflora. The results of this study can provide useful data for conservation and restoration of natural habitats of Korean endemic Eranthis byunsanensis and for the development and growth of this species for ornamental purposes.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.25 no.4
• /
• pp.94-106
• /
• 2022

In order to increase timber self-sufficiency, Korea's 6th Basic Forest Plan aims to increase the density of forest roads to 12.8 m ha^-1 by 2037. However, due to rapid re-forestation, current management infrastructure is insufficient, with just 4.8 m ha^-1 of forest roads in 2017. This is partly due to time and cost limitations on the process of forest road feasibility evaluation, which considers factors such as topography and forest conditions. To solve this problem, we propose an eco-friendly and efficient forest road network planning method using a geographic information system (GIS), which can evaluate a potential road site remotely based on spatial information. To facilitate such planning, this study identifies forest road construction priorities that can be evaluated using spatial information, such as topography, forest type and forest disasters. A method of predicting the optimal route to connect a forest road with existing roads is also derived. Overlapping analysis was performed using GIS-MCE (which combines GIS with multi-criteria evaluation), targeting the areas of Cheongsong-gun and Buk-gu, Pohang-si, which have a low forest-road density. Each factor affecting the suitability of a proposed new forest road site was assigned a cost, creating a cost surface that facilitates prioritization for each forest type. The forest path's optimal route was then derived using least-cost path analysis. The results of this process were 30 forestry site recommendations in Cheongsong-gun and one in Buk-gu, Pohang-si; this would increase forest road density for the managed forest sites in Cheongsong-gun from 1.58 m ha^-1 to 2.55 m ha^-1. This evaluation method can contribute to the policy of increasing timber self-sufficiency by providing clear guidelines for selecting forest road construction sites and predicting optimal connections to the existing road network.