• Tunnel and Underground Space
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• v.18 no.3
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• pp.185-193
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• 2008

We have carried out Pearson-type chi-square tests on the orientation data of joints from different depths in order to estimate the homogeneity of joint orientations obtained from a borehole. The orientation data of joints were collected from two non-foliated massive rocks of granitic gneisses in South Korea since orientations of joints in folded metamorphic rocks, for example, are controlled by foliation and also changes as the orientations of foliation change by folding. Borehole images were used for the analysis of the orientations of individual joints. The orientation data were subdivided into the upper level data and lower level data. The data from these two levels are plotted on the patch net consisting of 21 orientation patches. Then, the two patterns on the patch net were analyzed using a contingency table. From the chi-square test on the data collected from two sites, we found that some data sets show statistically meaningful differences in orientations of joints. Since joints are one of the important parameters in determining the physical properties of rock masses, in situ investigation of joints are desirable in the geotechnical investigation and also in design of subsurface structures (e.g. tunnels and underground storages).

• 한국해양학회지
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• v.13 no.1
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• pp.1-8
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• 1978

A seismic reflection Survey was carried out in the offshere area between Geoje Island and Namhae Island, utilizing the echosounder with the frequency 28KHz and thd Uniboom with the filter band 800∼2000Hz. The results show the submarine topography, sedimentary layer structure and the depth distribution of the base rock. The water depth of the sea in the survey area is less than 80m; up to 40m contour line the sea bottom surface has a slight dip(about 1/1000), while in the zone deeper than 40m the bottom topography has a irregular relief. The thickness of the whole sedimentary deposit is about 20∼70m and divided into 3 layers: Upper layer(A layer) with horizontal laminae, intermediate layer(B layer) with cross-bedding and groove structure, and lower layer(C layer) not showing any sedimentary structure on the seismic reflection profile. The surface of the base rock is deeper gradually in the south-eastern part of the survey area and extends to 140m depth. The vertical sediments sequences, composed of B layer and A layer, show the type of transgressive sequences. It is interpreted that B layer was formed at one period when the sea level was lower 40∼60 than the present and ince then, following the rising of the sea level, A layer was deposited.

• The Korean Journal of Petroleum Geology
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• v.1 no.1 s.1
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• pp.29-35
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• 1993

Seismic reflection data can be used to extract information about the velocity structure of the earth. This process is called a velocity inversion of the seismic data. However, it is difficult to recover a broad band reflection coefficient series because the frequency band of seismic trace is limited. The linear programming method has been examined to find the simplest velocity model that has frequency components consistent with the usable frequencies of the seismic trace and interval velocity data. The velocity structure of the earth is displayed in pseudovelocity section. After the linear program had been tested with a synthetic seismic trace, it was applied to the seismic reflection data of the Block Ⅱ in the Yellow Sea. By comparing the pseudovelocity section with sonic logs obtained from the well in the same area, it was possible to define the lithostratigraphy and the boundaries of Cretaceous volcanics and Cretaceous metavolcanics.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.479-490
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• 2002

The aim of this study is to evaluate the contributions of each hydrogeological factors to groundwater recharge ratios in order to determine areal estimates of recharges in entire inland area of South Korea. For this purpose, various statistical analyses and overlay techniques of GIS were conducted fur entire area and 4 river basins of South Korea. As a result, the spatial distribution of recharge, South Korea were visualized.

• Economic and Environmental Geology
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• v.18 no.4
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• pp.381-397
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• 1985

A petrological study has been done in the pyeongchang-Jaecheon area which is a northwestern part of the basement of Ogcheon zone for the purpose of comparison of the area to the Nogjeon-Yeongchun area which is the antipodal basement of the zone in the petrological and geotectonical view points. The major units of the area are Precambrian granitic gneissic complex, banded gneiss, linea ted leucocratic gneiss and pegmatitic leucogranitic gneiss in the west, elongated exposure of quartz schist (or partly quartzite) and phyllite, named as Jungdaegal-bong Group correlated to the lower sequence of Joseon Group, in the middle, and limestone and calcic dolomite, Iptanri Formation, correlated to the middle of Joseon Group in the east. Igneous plutons are distributed in the areas of gneissic complex and limestone formation as well as in the Eosangcheon and Daedaeri areas in the southeastern out of the area. Present study reveals that the gneissic complex are the products of granitization to metamorphism of amphibolite facies in the order of above mentioned from the metasediments of schists and calcareous rocks. A notable characteristics of the phyllite of Jungdaegal-bong Group is the presence of syntectonically segregated quartz rods in the forms of lens, swirl or boudinage in evenly distributed in the phyllitic to chloritic matrix. Igneous rocks range in composition from gabbro through diorite, granodiorite, to schistosed and porphyritic granites in stock and dike. The orogenic movement of the Ogcheon zone initiated in the middle Proterozoic time, pre-sedimentation of Ogcheon Group and superposed the granitization in Permian, Jurassic Daebo orogeny with granitic batholiths and stocks, and Cretaceous plutonic intrusion.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.4
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• pp.285-290
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• 2009

A suitable system for plant regeneration has been established for perennial ryegrass (Lolium perenne L.). In order to investigate the effects of genetic variations of perennial ryegrass in tissue culture response, calli were induced from mature seeds of five cultivars, 'Topgun', 'Accent', 'Renenge GLX', 'Tetrellite', 'Bison' and plant regeneration frequency was compared. Significant differences were observed among the cultivars in both callus induction and plant regeneration. Genotype 'Accent' consistently performed best in the callus formation and plant regeneration. These results can be used useful for molecular breeding of perennial ryegrass through genetic transformation.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.527-536
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• 2003

The Dokdo volcano in the south-central part of the East Sea is classified into 8 rock units. The units and sequence suggest that the Dok Island forms a small stratovolcano constructed from at least 3 times eruption cycles above the sea level and proceeded with transformation of a few different eruption styles during each cycle. Reconstruction of the volcanic form, from the geologic structures and spatial lithofacies changes, suggests that the island is remnants of the southwestern caldera rim of the stratovolcano whose central part lies several hundred meters to the northeast. The subaqueous volcano shows abig guyot, which looks like a shield volcano, that represents gentle slope at 90-175 m deep and relatively steep one in 200∼2,000m, and 25∼30km wise base on sea floor. Therefore the total Dokdo volcano represents a multiple volcano that stratovolcano with small caldera overlies the big guyot.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.3
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• pp.265-270
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• 2004

Plant regeneration from seed-derived callus of Kentucky bluegrass(Poa pratensis L. cv. Kenblue) was investigated. Callus induced on the medium supplemented with 2 mg/L 2,4-D and 0.2 mg/L BAP showed highest frequency of plant regeneration on the regeneration medium supplemented with 1 mg/L NAA and 5 mg/L kinetin. Callus induced in the dark condition showed higher regenerability than that induced in the dim light. MS medium was better than N6 and B5 medium in enhancing plant regeneration. Maltose was superior to sucrose in plant regeneration as carbon source in the medium.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.1
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• pp.31-34
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• 2001

When root initiation ratio of cut Italian ryegrass (Lolium multiflorum Lam.) stems was examined in several medium conditions containing different IBA concentration, most higher root initiation ratio was confirmed at 1.0 mg/$\ell$ of IBA and the ratio was 37.5%. When cut Italian ryegrass stems were treated in cold chamber at 4$^{\circ}C$ for 40 days and incubated in growth chamber at 26$^{\circ}C$ for 1 month, the root iniation result was 0.0% at MS-0 medium, 8.3% at MS-0.5IBA medium, 37.5% at MS-1.0IBA medium, 16.7% at MS-1.5IBA medium and 12.5% at MS-2.0IBA medium.

• Geophysics and Geophysical Exploration
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• v.1 no.3
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• pp.161-169
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• 1998

The Kunsan basin is a pull-apart basin which was formed during Tertiary. The pre-Tertiary section consists of various rock types, such as meta-sediments, igneous rocks, carbonates, clastics, and volcanics. Tertiary sections are the main targets for the petroleum exploration. In order to determine the optimum processing parameters of the basin, about 12 kinds of test processings were performed. The first main steps for the quality control is to determine the noisy or bad traces by examining the near trace section and shot gathers. The true amplitude recovery was applied to account for the amplitude losses due to spherical divergence and inelastic attenuation. Source designature and predictive deconvolution test were conducted to determine the optimum wavelet parameters and to remove the multiples. Velocity analysis was performed at 1km intervals. The optimum mute function was picked by locating the range of offsets which gives the best stacking response for any particular reflections. Post-stack deconvolution was tested to see if the quality of stacked data improved. The stacked data was migrated using a finite difference algorithm. The migration velocity was obtained from the stacking velocities using the time varying percentages. The AGC sections were provided for the structural interpretation. The RAP sections were used for DHI analysis and for the detection of volcanics.