• Journal of the Korean Geographical Society
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• v.42 no.3 s.120
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• pp.368-387
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• 2007

In order to explain geomorphological characteristics of the Korean Peninsula, it is necessary to understand the spatial distribution of tectonic movements and its causes. Even though geomorphological elements which might have been formed by tectonic movements(e.g. tilted overall landform, erosion surface, river terrace, marine terraces, etc.) have long been considered as main geomorphological research topics in Korea, the knowledge on the spatial distribution of tectonic movement is still limited. This research aims to identify the spatial distributions of tectonic movement via sequential analyses of Digital Elevation Model(DEM). This paper first developed a set of terrain analysis techniques derived from theoretical interrelationships between tectonic uplifts and landsurface denudation processes. The terrain analyses used in this research assume that elevations along major drainage basin divides might preserve original landsurfaces(psuedo-landsuface) that were formed by tectonic movement with relatively little influence by denudation processes. Psuedo-landsurfaces derived from a DEM show clear spatial distribution patterns with distinct directional alignments. Lines connecting psuedo-landsufaces in a certain direction are defined as psuedo-landsurface axes, which are again categorized into two groups: the first is uplift psuedo-landsurface axes that indicate the axis of landmass uplift; and the second is denudational psuedo-landsurface axes that cross step-shaped pusedo-landsurfaces formed via surface denudation. In total, 13 axes of pusedo-landsurface are identified in the Korean Peninsula, which show distinct direction, length, and relative uplift rate. Judging from the distribution of psudo-landsurfaces and their axes, it is concluded that the Korean Peninsula ran be divided into four tectonic regions, which are named as the Northern Tectonic Region, Center Tectonic Region, Southern Tectonic Region, and East Sea Tectonic Region, respectively. The Northern Tectonic Region had experienced a regional uplift centered at the Kaema plateau, and the rate of uplift gradually decreased toward southern, western and eastern directions. The Center Tectonic Region shows an arch-shaped uplift. Its uplift rate is the highest along the East Sea and the rate decreases towards the Yellow sea. The Southern Tectonic Region shows an asymmetric uplift centered a line connecting Dukyu and Jiri Mountains in the middle of the region. The eastern side of the Southern Regions shows higher uplift rate than that of the western side. The East Sea Tectonic Region includes south-eastern coastal area of the peninsula and Gilju-Myeongchun Jigudae, which shows relatively recent tectonic movements in Korea. Since this research visualizes the spatial heterogeneity of long-term tenonic movement in the Korean peninsula, this would provide valuable basic information on long-term and regional differences of geomorphological evolutionary processes and regional geomorphological differences of the Korean Peninsula.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.302-306
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• 2010

'Migwang' is a new japonica rice variety developed from a cross between SR15926-10-2-3-3-3 having a good canopy architecture and multiple disease resistance, and Iksan431 having a translucent milled rice and good eating-quality with a view of developing a new variety having multiple disease resistance by the rice breeding team at NICS, RDA in 2009. The heading date of this variety is August 15 and later than check variety, Hwaseongbyeo, by four days. 'Migwang' has 75 cm of culm length and 98 spikelets per panicle. This variety showed longer heading delay and higher spikelet sterility than those of Hwaseongbyeo while exposed to cold stress. This variety showed resistance to blast disease and bacterial leaf blight, but susceptible to rice stripe virus and planthoppers. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and short grain shape. 'Migwang' has better palatability index of cooked rice than that of Hwaseongbyeo. The whole grain rate of milled rice and milled rice recovery of 'Migwang' are higher than those of Hwaseongbyeo as 96.8% and 73.1%, respectively. 'Migwang' has 5.5 MT/ha in milled rice. 'Migwang' could be adaptable to the middle plain area, mid-western and southeastern costal areas and mid-mountainous areas in Korea.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.68-81
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• 2015

In this study, the correlation between the frequency of summer tropical cyclones (TC) affecting areas around Korea over the last 37 years and the western North Pacific monsoon index (WNPMI) was analyzed. A clear positive correlation existed between the two variables, and this high positive correlation remained unchanged even when excluding El Ni$\tilde{n}$o-Southern Oscillation (ENSO) years. To investigate the causes of the positive correlation between these two variables, ENSO years were excluded, after which the 8 years with the highest WNPMI (positive WNPMI phase) and the 8 years with the lowest WNPMI (negative WNPMI phase) were selected, and the average difference between the two phases was analyzed. In the positive WNPMI phase, TCs usually occurred in the eastern waters of the tropical and subtropical western North Pacific, and tended to pass the East China Sea on their way north toward Korea and Japan. In the negative WNPMI phase, TCs usually occurred in the western waters of the tropical and subtropical western North Pacific, and tended to pass the South China Sea on their way west toward the southeastern Chinese coast and the Indochina peninsula. Therefore, TC intensity was higher in the positive WNPMI phase, during which TCs are able to gain sufficient energy from the sea while moving a long distance to areas nearby Korea. TCs also tended to occur more often in the positive WNPMI phase. In the difference between the two phases regarding 850 and 500 hPa streamline, anomalous cyclones were reinforced in the tropical and subtropical western North Pacific, while anomalous anticyclones were reinforced in mid-latitude East Asian areas. Due to these two anomalous pressure systems, anomalous southeasterlies developed in areas near Korea, with these anomalous southeasterlies playing the role of anomalous steering flows making the TCs head toward areas near Korea. Also, due to the anomalous cyclones developed in the tropical and subtropical western North Pacific, more TCs could occur in the positive WNPMI phase.

• Geophysics and Geophysical Exploration
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• v.3 no.1
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• pp.1-6
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• 2000

The 1 $km^2$ area studied is located in Sukchun-ri, Hwasung-koon, the southern part of Kyeonggi-do. Even though this site has been known as a contaminated area caused by seawater intrusions, geophysical and geochemical surveys have never been carried out at the site to determine the extent of the seawater contamination and to investigate whether the seawater intrusion is in progress. The purpose of this study is to determine the extent of seawater contamination and a preferred channel of the seawater intrusion using geophysical methods such as DC resistivity surveys with Schlumberger array and a dipole-dipole array. In order to determine whether the seawater intrusion is in progress in the area, DC resistivity monitoring with Schlumberger array was performed. According to the resistivity map obtained from the inversion of the resistivity data measured with Schlumberger array, the study area is divided into two districts as relatively lowly resistive (less than 30 ohm-m) and highly resistive (more than 30 ohm-m) areas. The distribution of the lowly resistive area is consistent with the distribution of the layer composed of clay minerals, and the resistivity of this layer decreases slowly as approaching to the old seashore. Hydrogeological analysis shows that the clay layer within a distance of about 200 m from the seashore has been already contaminated by sea-water and its electric conductivity is 8 times higher than that of the sand layer covered by the clay layer. According to the results of the 2-dimensional DC resistivity surveys with a dipole-dipole array, there are two preferred channels of the seawater intrusion in the site, and both the channels are in the NW-SE direction from the old seashore. The lowly resistive zone in the southern channel extends to a depth of 80 m. The DC resistivity monitoring with Schlumberger array was carried out along the preferred channel which has the low resistivity Bone (fracture zone) that extended to a depth of 80 m. The time series of apparent resistivity, measured at a distance of 260 m from the old coast line, fluctuates with a period of 12 hours. From these observations, it can be concluded that the seawater intrusion caused by tidal action is still in progress along the fractured zone interpreted by the DC resistivity surveys with a dipole-dipole array.

• Korean Journal of Plant Resources
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• v.22 no.2
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• pp.116-122
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• 2009

Heteropappus arenarius Kitam., an autumn-flowering biennial belonging to wild chrysanthemums, is found to be native in southeastern coastal area and Jeju island of Korea. It could play a good role for ground cover plants on a large-scale landscape area, especially, barren soil or sloping hillside. This study was initiated to screen optimum germination temperature influenced by local strain and harvesting stage of H. arenarius. The following was the response of seed germination between local strain and temperature. The average of final germination percentage (FG) was the highest in 'Guryongpo' (89.7%) among four local strains, followed by 'Gujwa' (87.3%), 'Gampo' (87.3%), and 'HKNU-I' (71.5%). The average of $T_{50}$ was shorter in 'Gujwa' (3.6 d) and 'Guryongpo' (4.0 d) than the others. The average of FG and $T_{50}$ was the highest as 76.2% and shortest as 3.6 d in $20^{\circ}C$, respectively, followed by $30^{\circ}C$, $25^{\circ}C$, and $15^{\circ}C$. In case of 'Gujwa', however, FG and T50 was higher in $20^{\circ}C$ and shorter in $15^{\circ}C$ than others. In the relationship between harvesting stage and temperature, the average of FG was greatly higher in Stage III (90.7%) and Stage IV (88.6%) than the others including Stage II (35.7%) and Stage I (26.0%). The average of $T_{50}$ was shorter in Stage IV (3.7 d) and Stage III (4.3 d) than the others, which showed less than 50% of FG. Nevertheless, the available range of seed harvesting stage was from Stage I to Stage IV because H. arenarius seeds could germinate at all stages. In conclusion, it was recommended that the optimum temperature and harvesting stage was $20^{\circ}C$ and Stage $III{\sim}IV$, respectively, for seed germination of H. arenarius.