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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean earth science society
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Journal DOI :
The Korean Earth Science Society
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Volume & Issues
Volume 19, Issue 6 - 00 1998
Volume 19, Issue 5 - 00 1998
Volume 19, Issue 4 - 00 1998
Volume 19, Issue 3 - 00 1998
Volume 19, Issue 2 - 00 1998
Volume 19, Issue 1 - 00 1998
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The Subsurface Stratigraphy of Cheju Volcanic Island, Korea
Son, In-Seok ; Lee, Mun-Won ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 581~581
The goal of this study is to investigate the subsurface stratigraphy of Cheju volcanic island by analysing core data. The subsurface stratigraphy of the island is as as follows: The basement rock is Cretaceous granites and tuff, which are overlain successively by Sehwari Formation, Basal basalt (APB, OAB, FOB), Seogwipo Formation and basalt (FOB, Hawaiite and so on). The depth of granite basement ranges from 320 m to 950 m below sea level and the paleo-geomorphic relief of the island in the granite shows high difference level such as about 630 m in altitute. The depth of basal tuff ranges from 117 m to 227 m below the mean sea level. The thickness of the tuff ranges from 41 m to 773 m, and the paleo-geomorphic relief is even more than that of granite basement. The Sehwari Formation is composed of the unconsolidate silty clays and sands, containing shell fossils. The depth of this formation is from +30 m to -245 m and distributed along the coastal area. The basal basalt is consisted of aphanic basalt (APB), olivine augite basalt (OAB) and feldspar olivine basalt (FOB). The age of basal basalt shows a range from 2.22 Ma to 0.7 Ma. The Segwipo Formation, which is distributed along the coastal area, is composed of beach sediments containing several kinds of shell fossils. The age of the formation is estimated from 0.7 Ma to 0.4 Ma.
A Case Analysis of the Heavy Rainfall in Youngdong Area
So, Seon-Seop ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 590~590
The synoptic scale features of the local heavy rainfall event in Youngdong area were investigated using the 2.5 degree gridded data obtained from the European Center for Medium Range Weather Forecasts (ECMWF) in domain 20N∼50N and 100E∼150E from 25 August to 28 August 1982 and from 24 September to 27 September 1988. The analysis indicates that the heavy rainfall was developed when the cloud band located over Youngdong area. Before the event in Youngdong area, the atmosphere over Youngdong area was very unstable (K-index: 25∼30) and had a large amount of moisture by north-easterly wind. Also the divergence of air cause the heavy rainfall when the lower level convergence field and the upper level divergence field are vertical. During the event, the heavy rainfall in Youngdong area depended on unstable atmosphere and the structure of the moisture atmosphere by the lower level wind direction and p-velocity in accordance with the specific topography and the lower level convergence field and the upper level divergence field.
Forward Modeling of Magnetic Logging for a Finite Line of Dipoles
Kim, Jin-Hu ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 610~610
A general closed-form expression for a forward modeling of magnetic logging has been derived for an arbitrarily oriented and arbitrarily dipping finite line of dipoles with arbitrary direction of magnetization in arbitrary location of borehole. By using this expression total and horizontal component as well as vertical component of magnetic anomalies can be obtained. Numerical results of a magnetic logging show that the magnitude of the magnetic anomalies is directly proportional to the magnetic moment per unit length of the line of dipoles, and that of the magnetic anomalies decreases as the distance from the target to the borehole increases. They also show that the shape of the magnetic anomalies is determined by the variations of the input parameters, such as length, burial depth, bearing, dip, declination, and inclination of the line of dipoles located in a given magnetic field of the Earth. This forward modeling algorithm can be used in inversion to identify location and characteristics of the line of dipoles.
Hypocenter Determination for the Crust with Various
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 616~616
Many programs of hypocentral location assume that the ratio of P-wave velocity (
) to S-wave velocity (
) is constant over the crustal layers. From this assumption, S-wave travel time is obtained simply from the P-wave travel time by the multiplication of the constant
ratio. However, if the
ratio is not constant, the hypocenter located by these program may largely deviate from the real focus. A program of hypocentral location is developed to calculate travel times for the crustal model with layers of the various
ratio. This program incorporates both observe and priori data and successfully reduce the residual between observed and theoretical times. In addition, our program can quantify the weight of the observation by introducing reading error
CCD Photometric Study of a δ Scuti Variable HR 2107
Park, Seon-Yeop ; Gwon, Seok-Min ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 622~622
High time-resolution, real-time CCD differential photometric observations were carried out for a multiperiodic δ Scuti type variable, HR 2107 (1 Mon) from Feb. 1994 to Jan. 1995. Johnson's V band photometric data of total 6 nights were obtained with the Automatized Differential Photometry System (ADPS) which is attached to the 24-inch Cassegrain telescope of Mt. Sobaek Observing Station. In order to determine pulsation frequencies we have been applied the power spectrum analysis in the frequency domain. For the frequencies determined from the power spectrum analysis, we again applied linear least squares fitting to the observed light curves and found best-fit amplitudes and phases for all input frequencies. From the analysis we detected 4 pulsation frequencies for HR 2107: f₁=7.390 c/d, f₂= 7.445 c/d, f₃=14.770 c/d, and f₄=14.825 c/d. From the comparison of the detected frequencies and amplitudes with those of Desikachary (1974), we have found that the pulsation frequencies of HR 2107 did not show any meaningful change. However, the amplitudes of all pulsation frequencies show significant difference with those of Desikachary (1974). This fact may suggest that the amplitudes of the pulsations have been changed during the past twenty years.
Petrochemistry and Sr . Nd Isotopic Compositions of Boeun Granite, Korea
Sin, In-Hyeon ; Park, Yeong-Seok ; Park, Cheon-Yeong ; Jeong, Yeon-Jung ; Shigeru Iizumi ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 632~632
The content of major and trace elements, Rb-Sr isochron age and Sr - Nd isotope compositions were determined for granites in the Boeun areas of the middle part of the Ogcheon Fold Belt in Korea. The granites of the this area are distributed in the shape of a batholith, and they intrude the middle part of Ocheon Fold Belt. These granites includes the granodiorite or granite of fine or coarse grained. The geochemical characters of this granite indicated to crystallize from a calc-alkaline series and to enrich in alkali elements by magmatic differentiation, they appear to form at the environment of continental plate or island arc. The isotopic compositions of the granites give a defined Rb-Sr whole rock isochron age of 272.8±3.6Ma corresponds to the middle Permian Period, the Sr initial ratio is 0.711864±0.000054.
(2σ) isotope ratios are 0.511506∼0.511869. And, εNd values are -12.98∼-19.05, εSr values are +96.89∼+111.99, and model age is 2.05∼2.58 Ga. As a result, the isotopic evidence from granites of the study area indicate that their source material may be derived from partial melting of continental crust materials.
The Determination of Rock Mass Rating (RMR) with Joint Spacing and its Relation to Slope Stability
Jeong, Sang-Won ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 641~641
Rock Mass Rating (RMR) with joint spacing is determined near Carson City, Nevada, U.S.A. along the Highway Route No. 50 without direct data from drilling core samples suggested by Deere and Miller (1966) and Aufmuth (1994). In order to determine RMR, six critical parameters are measured: (1) Joint orientation and uniaxial compressive strength, (2) Joint spacing and its frequency, (3) RQD estimate, (4) Condition of joint, (5) Groundwater wndition, and finally, (6) Rating adjustment. The resultant RMR value of the rating is 72. The overall Rock Mass Rating suggests that the rock tested is considered as a good rock, which is classified as Class II. The slope stability of the study area was evaluated in terms of factor of safety as well as stereographic interpretation. For the analysis of stereographic interpretation, the computer programs of DIPS and DISCANAL are used. The factor of safety of the slope in the study area was determined 0.92 to 1.12, which is greatly dependent on the angle of friction of the slope. It turns out that stability of the slope is unstable towards the southeastern direction of the intersection of joints due to sliding. However, there is no direct relationship between the RMR values and the condition of slope stability.
Empirical Orthogonal Function Analysis of Microwave Satellite Data for Lower Stratospheric Temperature
Yu, Jeong-Mun ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 649~649
Utilizing satellite Microwave Sounding Unit (MSU) Channel 4 (Ch4) brightness temperature data for the climate analysis of lower stratosphere (∼70 hPa), monthly mean climatology derived from the 18 year (198097) data over the globe and the correlation between Ch4 and tropospheric temperature have been investigated. Then an Empirical Orthogonal Function (EOF) analysis is performed on the Ch4 monthly mean and its anomaly. Negative correlation between Ch4 and sea surface temperature occurs in most of southern hemispheric oceans, suggesting that the global warming at the earth surface is coupled with lower stratospheric cooling. Negative correlation between Ch4 and midtropospheric temperature is also dominant over the extensive regions. However, more convective areas in tropics show positive correlation, implying the barotropic feature of monthly-averaged atmosphere and the active exchange in heat between mid-troposphere and lower stratosphere. The first mode of monthly mean Ch4 which shows annual cycle is predominant (≥90.0%) over the tropical Pacific. In the meanwhile, the eigenvectors and principal component time series of the first mode in the anomaly analysis reflect well the global lower stratospheric warming due to two major volcanic eruptions. In addition, the lower stratospheric temperatures over both the Korean peninsula and the tropical Pacific tend to increase together due to the eruptions in tropics. The second mode over the Pacific shows zonally symmetrical distribution to the equator, and Quasi-Biennial Oscillation (QBO) in corresponding time series. In the third mode, the temperature of two areas (150 W, 10 S and 10 N) decreases over the tropical eastern Pacific during four El Nifio periods with a dumbbell-shape pattern. The pattern is similar to, but out of phase with that in mid-troposphere. This study suggests that MSU Ch4 data can be used in monitoring the thermal state and climatic variation for lower stratosphere.
Depositional Processes and Evolution of the Hampyong-Bay Tidal Flat, Southwestern Coast of Korea
Kim, Yeo-Sang ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 664~664
The depositional processes and stratigraphic evolution for the intertidal deposits of Hampyong Bay, southwestern coast of Korea, have been studied by analyzing the surface sediments and core sediments. The results show that stratigraphy of Hampyong Bay may be subdivided into three units according to the unconformable boundaries. Cores taken from the intertidal flat reveal that the Holocene tidal deposit, less than 9 m in thickness, overlies the preHolocene unit II in the form of a transgressive pattern. The surficial sedimentary facies (Unit I), consisting of mud, sandy mud, gravelly mud, gravelly muddy sand, muddy gravel, and gravelly sand, generally coarsens landward because of the input of coarse fraction by sea cliff erosion. Physical sedimentary structures are strongly bioturbated, but some primary structures, such as thinly interlayered bedding and lenticular bedding, are locally found in the mudflat facies. Unit II is composed of lower gray homogeneous mud and upper semiconsolidated brown mud. The former have plant roots, and the latter is characterized by abundant crab burrows. This unit is interpreted to have been deposited in the intertidal environment over 47,000 years B.P. The evolution of Hampyong-Bay basin is interpreted as follows: Unit II was deposited under the intertidal regime when Hampyong Bay was submerged during Riss-Wurm interglacial period. Thereafter, the basin was subaerially exposed and eroded during the last glacial period. Since then, the beginning of Holocene interglaciation and the progressive inundation of the bay have formed a transgressive tidal sequence (Unit I).
Satellite Image Analysis for the Geologic Structure and Land Surface Environments in the Chugaryung Rift Valley Near Cholwon
Song, Mu-Yeong ;
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 675~675
The surface environmental characteristics around the lava plateau of Cholwon plain in Chugaryung Rift Zone are studied comparing the geological research result, the topographical digital elevation distribution and the multispectral data of the Landsat TM. According to the digital terrain distribution, the last lava eruption is verified to have originated at the Mt. Ori, 2 km southwest away from Pyeonggang, and spreaded to outskirts, especially flowing southward along the Hantan River up to Jeonkok. The satellite multispectral data analysis could not present the detail geological distribution, but only the scheme of the boundary between the lava plateau and the bedrock, which is distinctive in topography. The general landcover is easily classified into vegetation, water and dried soil, showing their characteristics in band ratios such as 2 to 5 of B4/B3 for vegetation, 10 to 25 of B1/B7 for water, and 2 to 3 of B5/B2 for soil or cement cover in cities. NDVI analysis and forest survey in the mountains near Cholwon have shown around 0.15 for needle leaf forest indicating the highest value in April scene, whereas larger than 0.5 in September but less than 0.05 in April for deciduous forest. April's NDVI image suggests that the persistent needle leaf forest is very active in the mountains far west and near northeast from Pyeonggang in North Korea, and around Kalmalup in South Korea, but not active in the Demilitarized Zone. September's NDVI image shows that the vegetation is vigorous in DMZ and mountain areas rather than in plain areas cultivating for agriculture. It is remarkable that there are relatively many medium sized reservoirs in North Korea just north side of DMZ and the north and south boundaries of DMZ are distinguishable. Considering the pixel's resolution (30 m), the military guard route seems to be strong in spectral reflectance comparing with the environs in spite of its small size. The unsupervised landwver classification presents different patterns according to the year and season and then the classification is not so effective and need to be supported by any new approach.
University Students' Misconceptions of the Calendar
Journal of the Korean earth science society, volume 19, issue 6, 1998, Pages 684~684
A calendar is a system of organizing units of time for the purpose of reckoning time over extended periods. Both the solar calendar and the lunar calendar are used in Korea. The lunar calendar, which is based on the the moon's phases, can not account for the change of seasons. So it adapts 24 solar terms by 15 segments of solar longitude. This study is to identify university students' misconceptions of the calendar by letting them answer the cause of seasons and choose the better calendar to account for seasons. The results show 143 out of 271 students have the misconceptions that the lunar calendar can account for seasons better than the solar calendar. Further educational implications are discussed.