• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.71-76
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• 2008

Study of terrestrial impact craters is important not only in the field of the solar system formation and evolution but also of the Galactic astronomy. The terrestrial impact cratering record recently has been examined, providing short- and intermediate-term periodicities, such as, ${\sim}26$ Myrs, ${\sim}37$ Myrs. The existence of such a periodicity has an implication in the Galactic dynamics, since the terrestrial impact cratering is usually interpreted as a result of the environmental variation during solar orbiting in the Galactic plane. The aim of this paper is to search for a long-term periodicity with a novel method since no attempt has been made so far in searching a long-term periodicity in this research field in spite of its great importance. We apply the cepstrum analysis method to the terrestrial impact cratering record for the first time. As a result of the analysis we have found noticeable peaks in the Fourier power spectrum appear ing at periods of ${\sim}300$ Myrs and ${\sim}100$ Myrs, which seem in a simple resonance with the revolution period of the Sun around the Galactic center. Finally we briefly discuss its implications and suggest theoretical study be pursued to explain such a long-term periodicity.

• Asian review of World Histories
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• v.1 no.1
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• pp.85-116
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• 2013

The theory of terrestrial impact which has been developed by the astronomy scientists since 1970s is employed for this article in a new angle that atmospheric conditions of our planet should be adopted in the interpretation of the history of mankind. Large and small terrestrial impacts must be acknowledged as key tasks in terms of the study of 'world history'. The Society of Interdisciplinary Studies has already advocated that the 'Bronze Age Civilization' was strongly influenced by the long term terrestrial impact phenomena. Based on historical materials from Korea, the present study was able to identify the years 680-880, 1100-1220, 1340-1420, and 1490-1760 as periods in which territorial impacts occurred.

• Journal of Astronomy and Space Sciences
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• v.18 no.3
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• pp.191-208
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• 2001

We have recently compiled a database of the properties of 192 impact craters, which supercedes previous compilations. Using our database, the impact structures found in North America, Europe and Australia have been examined; these cratonic areas have been relatively stable for considerably long geological periods, and thus have been best preserved. It is confirmed that there is a close correlation between the geological epoch boundaries, the epochs of mass extinctions, antral the "timing" of impacts. In addition, the terrestrial cumulative flux of objects >20km is found to be $1.77{\times}10^{-15}km^{-2}yr^{-1}$, over the last 120 Myr, which is much smaller than the published values in McEwen et al. (1997) and Shoemaker (1998) ($5.6{\pm}2.8{\times}10^{-15}km^{-2}yr^{-1}$. For terrestrial impact structures with D> 50 km, the apparent cumulative flux over the last 2450 Myr is ~50 times smaller than the corresponding value for the Moon. If we assume that the Earth and the Moon suffered the same level of bombardment over this time, this would mean that the actual flux of impacting bodies, capable of making craters with D)50 km, was ~ 50 times larger than the apparent flux estimated from the currently known terrestrial records.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.3
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• pp.35-46
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• 1997

The objective of this study is to investigate actual conditions of terrestrial vegetation part in Environmental impact statement, and to prepare a proposal for the efficiency of Environmental Impact Assessment. 13 E.I.S.s made out during 1996.6-1997.5. have been chosen and analysed with respect to scope of survey, item of survey, method of survey, and result of survey. Actual conditioins of terrestrial vegetation part in E.I.S. are summarized as follows : 1. The mean number of total participants in drawing up E.I.S. is 26.0 persons, that of participants in terrestrial vegetation part is 2.3 persons. 2. In case of planar project, the mean of scope of survey is 16.1 times as large as area of project . In case of linear project, the scope of survey has been determined arbitrarily. 3. The most part of survey has been dependent on literature, and field survey has been practically neglected. 4. Results of survey mostly missed the point that E.I.A. pursues. And proposals are as follows : 1. Participants in terrestrial vegetation part in drawing up E.I.S should be increased. 2. It is necessary to subdivide scope of survey in view of difference between planar project and linear project. 3. As for item and method of survey, field survey should be specially reinforced. 4. Several sheets of map as results of survey should be included in E.I.S. The vegetation map, the D.G.N. map, and the planting map should be included and drawn by smaller scale as possible.

• Journal of Environmental Impact Assessment
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• v.4 no.1
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• pp.37-46
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• 1995

This study was carried out to find the problems of assessment on terrestrial ecosystem part in environmental impact analysis(EIA) and to suggest the proper amelioration measures by analyzing 19 environmental impact statements(EIS) published during the period from 1991 to 1994. The results obtained from this study were as follows. Field survey for the investigation of fauna and flora in project areas should be conducted at least 3 times a year and name of investigator should be written on the EIS clearly. Increase or decrease in degree of green naturality and productivity cannot be an absolute criteria for expressing the amount of changes in ecosystem. Evaluation for the ecosystems and their composition in project area is more important than presenting merely the increase or decrease in degree of green naturality and productivity. Alleviation measures in 19 EISs analyzed in this study were summarized into 6 types: They are establishment of landscape plan, transplanting of useful trees preservation of big tree and protected species, restoration and preservation of existent vegetation, establishment of soil conservation measures and diminution of the impact on animal. However, they were somewhat insufficient because they wouldn't suggest the alleviation measures in detail. The more positive counter-proposals are needed to decrease the impact of the project on terrestrial ecosystem.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.175-181
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• 2006

This paper addresses an in-depth analysis of the stratosphere-to-Earth co-channel interference produced by high-altitude platforms (HAPs) and proposes a new methodology for the evaluation of its impact to terrestrial systems in terms of fractional degradation in performance, taking into account parameters such as HAP's mobility, realistic distribution of azimuth and elevation angles of the terrestrial microwave links (TMLs), and gradual high-altitude platform network (HAPN) loading. Simulations performed for different HAPN configurations, prove that the implementation of the methodology proposed, may lead to a more efficient use of the spectrum shared between the two services.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.199-208
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• 2006

The terrestrial impact cratering record recently has been examined in the time domain by Chang & Moon (2005). It was found that the ${\sim}26$ Myr periodicity in the impact cratering rate exists over the last ${\sim}250$ Myrs. Such a periodicity can be found regardless of the lower limit of the diameter up to D ${\sim}35km$. It immediately called pros and cons. The aim of this paper is two-fold: (1) to test if reported periodicities can be obtained with an independent method, (2) to see, as attempted earlier, if the phase is modulated. To achieve these goals we employ the time/frequency analysis and for the first time apply this method to the terrestrial impact cratering records. We have confirmed that without exceptions noticeable peaks appear around ${\sim}25$ Myr, corresponding to a frequency of ${\sim}0.04(Myr)^{-1}$. We also find periodicities in the data base including small impact craters, which are longer. Though the time/frequency analysis allows us to observe directly phase variations, we cannot find any indications of such changes. Instead, modes display slow variations of power in time. The time/frequency analysis shows a nonstationary behavior of the modes. The power can grow from just above the noise level and then decrease back to its initial level in a time of order of 10 Myrs.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.792-795
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• 2004

This paper is an interference analysis from S-DAB(Satellite-Digital Audio Broadcasting) into terrestrial IMT-2000 systems intending to use the band 2630-2 655 MHz and that could be used to determine the impact of S­DAB on terrestrial IMT-2000 in the context of co-frequency sharing through the development of pfd masks.

• The Korean Journal of Food And Nutrition
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• v.24 no.2
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• pp.166-172
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• 2011

This study was conducted to assess food safety knowledge of college students according to mass-media reports. To accomplish this, a survey was conducted to investigate the reliability, of primary mass-media sources on Bovine Spongiform Encephalopathy(BSE) as well as the preferences of college students. The most common sources of media consumed by male and female students were terrestrial television(TV)(60%), the internet(21%), and newspapers(11%) and terrestrial TV(60%), newspapers (18%), and the internet(17%), respectively. The preferences for media of major and non-major students were terrestrial TV(64%), newspapers(17%), and the internet(14%) and terrestrial TV(51%), the internet(22%), and newspapers(19%), respectively. The reliability of media as viewed by male students were as follows: terrestrial TV(53%) and the internet(40%), whereas for female students, these values were terrestrial TV(55%) and the internet(37%). The reliability of media as viewed by major and non-major students was as follows: terrestrial TV(67%) and the internet(28%), and terrestrial TV(44%) and the internet(44%), respectively. In the case of male students, the primary sources for information regarding BSE were terrestrial TV(54%) and the internet(38%), whereas for female students, the primary sources were terrestrial TV(57%) and internet (37%). In the case of major students, the primary sources for information regarding BSE were terrestrial TV(52%) and the Internet(40%), and for non-major students, the internet(47%) and terrestrial TV(39%). Both male and female students were found to have less knowledge regarding prions, SRM(Specified Risk Materials), MM(methionine-methionine) type genes, and cow above 30 months associated with BSE compared to the other factors associated with this disease. The BSE-related knowledge held by major and non-major students was revealed unknown more than the majority of responses. Based on these results, greater effort should be made to provide meaningful information to improve the food-safety knowledge of college students according to mass-media.

• The Bulletin of The Korean Astronomical Society
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• v.29 no.2
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• pp.22.1-22.1
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• 2004