• The Korean Journal of Quaternary Research
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• v.24 no.1
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• pp.35-45
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• 2010

The aims of this study are to clarify the geomorphological development of a alluvial plain and discuss the vegetation environments and agriculture activities in the Wangpo-River alluvial plain at Neungsan-ri, Buyeo by analyzing geomorphological classification, sedimentary facies and age datings. The alluvial plain at Wangpo-River was formed by the influences of Geum-River with the sea-level rising during the Holocene. The basin of Wangpo-River consists of natural levees, back marsh-type alluvial plains, valley plains and hills. The natural levees by Geum-River largely distributes at the area where Wangpo-River flows to Geum-River and the alluvial plains at the middle and lower reach are the back marsh areas of Geum-River. Moreover, the area along Wangpo-River show higher contents of coarse materials and thinner peat sediments than the back marsh. The lower sandy deposits in the alluvium of Wangpo-River was formed with the influences of human in the Bronze Age during the sea level falling and the peaty deposits was formed due to the water level rising of Wangpo-River during the sea level rising in the early Iron Age.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.832-838
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• 2011

The shock absorber with magnetic effect is suggested for a lunar lander. The shock absorber consists of a metal tube, a piston rod, and several permanent magnets moved by a piston rod in the tube, and the shock energy can be dispersed and dissipated by magnetic effects such as the magnetic force existed between a metal and magnets and the eddy current effect generated by a relative motion with a conductor and magnets. Besides, the shock-absorbing effect similar to that of a coil spring can be obtained by arranging the magnets in line, which are facing the same polar each other. The device has a very simple structure and is usable in space due to the unnecessariness of any oil or gas. The shock absorber was designed and manufactured for experiments and its spring and damping characteristics were studied by the theoretical, analytical and experimental methods.

• The Korean Journal of Quaternary Research
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• v.15 no.1
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• pp.53-61
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• 2001

To examine the effects of El Nino-Southern Oscillation (ENSO) on the tree growths of central Korea, tree rings of Korean pine(Pinus koraiensis) , Japanese red pine (Pinus densiflora) and yew (Taxus cuspidata) were analyzed. Korean pine and red pine samples were collected from 4 and 7sites in Sorak Mountain ranges, respectively ; yew from one site in Sobaek Mountain. Correlations between ring-width and monthly temperature data showed generally positive relationships for the Korean pine and yew chronologies, but negative ones for the red pine chronologies. In the analysis of correlation between ring-width and monthly S0 index data, only one Korean pine chronology at the lower Hangaerung valley site, and one red pine chronology at Baekdamjang shelter site showed significant relationships ; negative with April SOI for the former and positive with previous August-September SOI for the latter. The other chronologies at higher elevation sites did not indicate any significant correlations with SOI.

• The Korean Journal of Quaternary Research
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• v.15 no.1
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• pp.29-35
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• 2001

The coastal deposits along Moonamni, Kangwon Province, Korea have been investigated by using deeply cored sediments(down to the basement rocks : Pre-Cambrian metamorphic rocks and granitic rocks) in order to understand and propose the late Quaternary stratigraphy and related major unconformities. Three major stratigraphic -depositional units are proposed. The neolithic cultural sites in the Moonamni area are considered as middle Holocene coastal dunes, which were developed due to active supply of beach sands from Unit I(Holocene transgressive deposit). Such coastal dune sediments are characteristic in the upper part of Unit I(Holocene in age). So far, Unit II and Unit III are considered as continental deposits, such as fluvial-swamp and alluvial deposit, respectively.

• The Korean Journal of Quaternary Research
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• v.25 no.2
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• pp.1-15
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• 2011

The ODP (Ocean Drilling Program) has been greatly contributed to the progress of Earth Science through the strong international cooperation with its name changed from DSDP DSDP(Deep Sea Drilling Program), IPOD (International Phase of Ocean Drilling) to IODP (Integrated Ocean Drilling Program). The IODP program which was launched about ten years ago will continue to develop toward the 2nd phase of scientific targets through the tight international cooperation. Distinguished scientific results from the various expedition as well as new phase of IODP structure and its important role that enhance the new scientific fields are summarized in this study. In particular, Arctic Expedition and deep-biosphere and high resolution climatic study that was not performed in previous ODP stages, will be extensively conducted in coming new 2nd IODP stages. Likewise, through strong international cooperation, it is expected that IODP would play an important role in Earth Science developments.

• The Korean Journal of Quaternary Research
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• v.25 no.2
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• pp.39-48
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• 2011

Phytolith analysis of sediments at the river mouth of valley bottom plains in Myosa-ri, Haman is performed. By the phytolith results, Phragmites and Oryza sativa are dominated in the lower horizon. An abundance of Paniceae and Andropogoneae indicates the active agricultural activities under wet conditions. Moreover, the results of archeological studies suggest the paddy fields in the Three States Age. The phytolith assemblages are dominated in the middle horizon and they gradually increase in the upper horizon. The rice cultivation layer is not proportional to total phytolith yield due to the dominance of Oryza sativa in the lower horizon. However, because the Oryza sativa are continuously observed over the entire sediments, it is suggested that there had been the agricultural activities for the entire periods.

• The Korean Journal of Quaternary Research
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• v.22 no.1
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• pp.28-36
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• 2008

The present study has focused on the environmental changes and evidences for sedimentation in the Lake Khuvsgul catchment during the Holocene period, inferred from short core sediment (BO03) from the eastern shore of Borsog Bay, which were analyzed in order to review records of the Holocene climatic evolution and Holocene history in Northern Mongolia. For the purpose of reconstruction of natural phenomenon that occurred in the lake catchment system during the Holocene, physical and chemical properties including HCl-soluble material, biogenic silica, organic matter and grain size distribution of minerals in the core sediments have been analyzed in this study. The vertical variations in composition for these properties show distinctly that five lines of paleoenvironmental evidence occurred in the lake catchment during the Holocene. A modified age model resulting from AMS carbon dating for the BO03 core sediment shows timings of these environmental events at 9.5 Kyr BP, 8.0 Kyr BP, 5.6 Kyr BP and 3.2 Kyr BP, respectively. Paleoenvironmental changes in the Lake Khuvsgul catchment system during the Holocene highlight distinctive features of the hydrological regime and geomorphologic evolution in the lake catchment due to regional landscape and global climatic changes corresponding with the Holocene optimum and thermal optimum. In particular, the change of hydrologic regime based on the sedimentological evidence has been caused by not only overland flow due to melting water, but also base flow due to thick permafrost around Khuvsgul region.

• Journal for History of Mathematics
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• v.21 no.4
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• pp.169-182
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• 2008

This study has been searching for reasoning process solving the problem effectively in activities related to meaningful classification of pieces and geometric properties with tangram. In activities using some pieces of tangram, we systematically came up with every solution in classifying properties of pieces and combining selected pieces. It is very difficult for regular students to do this tangram. In order to solve this problem effectively, we need to show that there are activities using the idea acquired in reasoning process. Through this process, we do not simply use tangram to understand he concept and play for interest but to use it more meaningfully. And the best solution an not be found by a process of trial and error but must be given by experience to look or it systematically and methods to reason it logically.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.1-6
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• 2005

The ability to predict radar return from flying vehicles becomes a critical technology issue in the development of stealth configurations. Toward developing a CEM code based on Maxwell's equations for analysis of RCS reduction schemes, an explicit upwind scheme suitable for multidisciplinary design is presented. The DFFT algorithm is utilized to convert the time-domain field values to the frequency-domain. A Green's function based on near field-to-far field transformation is also employed to calculate the bistatic RCS. To verify the numerical calculation the two-dimensional field around a perfectly conducting cylinder is considered. Finally results are obtained for the scattering electromagnetic field around an airfoil in order to illustrate the feasibility of applying CFD based methods to CEM.

• The Korean Journal of Quaternary Research
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• v.5 no.1
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• pp.33-45
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• 1991

Sand bars associated with strong tidal currents are well developed in the subtidal zone near the Kokunsan islands. Tidal currents measured at sand bar in the area show an asymmetry in magnitude between flood and ebb currents. At the southern flank of the sand bar the currents are flood-dominant whereas the currents are ebb-dominant at the northern flank. The asymmetry is more distinctive as the currents become stronger during spring tide. Moreover, the flood-dominance along the southern flank is stronger than the ebb-dominance along the northern flank. Thus the flood current is more affective to the sand bar. The sandy bottom sediment is mostly transported as bedload by the tidal currents. The magnitude asymmetry of the tidal currents results in a net sediment movement in one direction. The direction is onshore in the south and offshore in the north, which may result in a net counterlookwise rotation of the sands around the sand bar. However, the sand bar may migrate towards onshore due to the more affective flood current in the south. The irregular V-shaped outline of the sand bar in the south also seem to reflect the strong effect of flood current.