• Journal of the Korean earth science society
• /
• v.31 no.1
• /
• pp.18-35
• /
• 2010

Facies analysis of the Late Triassic Hajo Formation, the lowest stratigraphic unit in the Chungnam Basin, shows that the lower part is composed mainly of breccias or conglomerates; the middle part, conglomerates; and the upper part, conglomerates and sandstones. The formation consists of 13 facies, which include horizontally stratified clastsupported conglomerate, clast-supported massive breccia, matrix-supported massive breccia or conglomerate, matrixsupported graded conglomerate, massive pebbly sandstone, horizontally laminated sandstone, massive sandstone, graded sandstone, inversely graded sandstone, planar cross-bedded sandstone, trough cross-bedded sandstone, low angle crossbedded sandstone, and massive mudstone. These are grouped into 4 facies associations (FA). FA I consisted of clastsupported and matrix-supported massive breccias presumably deposited in the talus or upper fan delta environment. FA II consists of matrix-supported massive conglomerate and horizontally stratified clast-supported conglomerate of cobble size and it seems to have been deposited in the upper fan delta environment. FAIII consisted of matrix-supported massive conglomerate of pebble size, horizontally laminated sandstone and massive sandstone may have been deposited in the middle fan delta environment. FAIV consists of massive pebbly sandstone, horizontally laminated sandstone and massive sandstone and presumably was deposited in the lower fan delta environment. In general the Hajo Formation is interpreted to have been deposited at the talus/upper fan delta environment in early stage; it might have been deposited in the alternating environments of upper and middle fan delta in middle stage; and it seems to have been deposited in alternating environments of middle and lower fan delta in late stage.

• Korean Journal of Remote Sensing
• /
• v.30 no.6
• /
• pp.797-807
• /
• 2014

The Sea Surface Temperature (SST) is one of the most important oceanic environmental factors in determining the change of marine environments and ecological activities. Satellite thermal infrared images can be effective for understanding the global trend of sea surface temperature due to large scale. However, their low spatial resolution caused some limitations in some areas where complicated and refined coastal shapes due to many islands are present as in the Korean Peninsula. The coastal ocean is also very important because human activities interact with the environmental change of coastal area and most aqua farming is distributed in the coastal ocean. Thus, low-cost airborne thermal infrared remote sensing with high resolution capability is considered for verifying its possibility to extract SST and to monitor the changes of coastal environment. In this study, an airborne thermal infrared system was implemented using a low-cost and ground-based thermal infrared camera (FLIR), and more than 8 airborne acquisitions were carried out in the western coast of the Korean Peninsula during the periods between May 23, 2012 and December 7, 2013. The acquired thermal infrared images were radiometrically calibrated using an atmospheric radiative transfer model with a support from a temperature-humidity sensor, and geometrically calibrated using GPS and IMU sensors. In particular, the airborne sea surface temperature acquired in June 25, 2013 was compared and verified with satellite SST as well as ship-borne thermal infrared and in-situ SST data. As a result, the airborne thermal infrared sensor extracted SST with an accuracy of $1^{\circ}C$.

• The Journal of Engineering Geology
• /
• v.25 no.1
• /
• pp.83-91
• /
• 2015

Few studies have investigated soil management policy and soil erosion measurement, whereas the occurrence of climate change requires the establishment of robust soil management systems and appropriate control of soil erosion. In this study, we developed a smart sensor for real-time quantitative measurements of soil erosion at the watershed scale. The smart sensor consists of an ultrasonic sensor, a rainfall meter, a solar cell, an RTU (remote terminal unit),and a CDMA (code division multiple access) and it was programmed to take a measurement every 30 minutes. The depths measured by the smart sensor were compared with data from terrestrial LiDAR. Experimental results showed a strong correlation in the depth of soil erosion between LiDAR and the ultrasonic sensor for the period from 22 August to 11 October 2013. Furthermore, the correlation coefficient between soil erosion depth (mm) and soil erosion volume (m³) was 0.9063 in the lower region of the watershed and is 0.9868 in the upper region. The proposed ultrasonic sensor technique can provide high-quality data for soil conservation and management systems in the future.

• Journal of the Korean earth science society
• /
• v.25 no.4
• /
• pp.242-250
• /
• 2004

The purpose of this study is to examine the interactive effects of teaching methods (expository and discovery) and learner's cognitive styles on the retention of learned content in Earth Science three weeks after an instruction is given. The subjects of this study were 1st graders of a boys' high school (n = 185) and co-educational high school (n = 189) in Gwangiu Metropolitan City of Korea. 92 students of the boys' high school and 95 students of the co-ed high school were assigned to the expository teaching group, and the rest of the boys' high school students and the co-ed high school students were to the discovery teaching group. The students were classified into field-independent learners, medium learners, and field-dependent learners based on their cognitive styles. The results of the study can be summarized as follows: First, the discovery teaching was more effective than expository teaching in terms of comprehension and application related to post-instruction retention of learned content. But there was no noticeable difference in knowledge domain. Second, the field-independent cognitive style was more effective than its counterpart, the field dependent cognitive style. Third, in the post-instruction retention test, not so much relevance was found between teaching methods and learner's cognitive style.

• Journal of The Korean Association For Science Education
• /
• v.30 no.2
• /
• pp.234-248
• /
• 2010

This study was conducted among 52 elementary pre service teachers not majoring in the natural sciences, who were taking Earth Science as an elective course at the University of Education located in central Korea. These elementary pre service teachers participated in story writing on the subject of earth system cycles over eight occasions. Changes in their understanding of the Earth's cycles were verified by comparing mind mapping exercises performed before and after the story writing. Afterwards, 43 out of the 52 subjects volunteered for structured interviews, in which they performed story-telling exercises. This study presents examples of story analysis that uses a variation of the wheel-shaped story map, and proposes story mapping as a preferred method of analysis. Before and after creative story writing activities, pre service teachers' mind mapping is analyzed to study possible positive changes. This study identified a gap between the instructional contents of the Earth system unit included in the 7th and current revised school curriculums on the one hand, and the conceptions expressed by the pre service teachers who studied these contents on the other.

• Journal of the Korean earth science society
• /
• v.38 no.1
• /
• pp.49-63
• /
• 2017

The geochemical results of the Chunyang granites located in the northeastern part of the Yeongnam Massif, indicate that these rocks have characteristics of calc-alkaline series in the sub-alkaline field, I-type and peraluminous. Most of the geochemical features in major and trace elements show systematic trends, which are similar to differentiation trends of the general Jurassic granitoids in South Korea. The Chunyang granite is largely enriched in mobile LILE (Sr, K, Rb and Ba) relatively immobile HFSE. They show LREE enriched patterns [$(La/Lu)_{CN}=41.8-73.2$] with a slightly negative Eu anomaly [$(Eu/Eu^*)_{CN}=0.89-1.10$]. There are no meaningful correlations in major and trace elements between the Chunyang granites and the Buseok plutonic rock which is the main unit of the Yeongju batholith. This result may suggest that these two plutonic rocks be not derived from the same parent magma. Tectonic discrimination diagrams indicate that the Chunyang granite was formed in volcanic arc environments. These geochemical characteristics results suggest that the Chunyang granite must have been generated at the active continental margin during the subduction of the Jurassic proto-Pacific plate.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.15-15
• /
• 2011

The radar observation system in Japan is operated by two governmental groups: Japan Meteorological Agency (JMA) and the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) of Japan. The JMA radar observation network is comprised of 20 C-band radars (with a wavelength of 5.6 cm), which cover most of the Japan Islands and observe rainfall intensity and distribution. And the MLIT's radar observation system is composed of 26 C-band radars throughout Japan. The observed radar echo from each radar unit is first modified, and then sent to the National Bureau of Synthesis Process within the MLIT. Through several steps for homogenizing observation accuracy, including distance and elevation correction, synthesized rainfall intensity maps for the entire nation of Japan are generated every 5 minutes. The MLIT has recently launched a new radar observation network system designed for flash flood observation and forecasting in small river basins within urban areas. It is called the X-band multi parameter radar network, and is distinguished by its dual polarimetric wave pulses of short length (3cm). Attenuation problems resulting from the short wave length of radar echo are strengthened by polarimetric wavelengths and very dense radar networks. Currently, the network is established within four areas. Each area is observed using 3-4 X-band radars with very fine resolution in spatial (250 m) and temporal (1 minute intervals). This study provides a series of utilization procedures for the new input data into a real-time forecasting system. First of all, the accuracy of the X-band radar observation was determined by comparing its results with the rainfall intensities as observed by ground gauge stations. It was also compared with conventional C-band radar observation. The rainfall information from the new radar network was then provided to a distributed hydrologic model to simulate river discharges. The simulated river discharges were evaluated again using the observed river discharge to estimate the applicability of the new observation network in the context of operations regarding flood forecasting. It was able to determine that the newly equipped X-band polarimetric radar network shows somewhat improved observation accuracy compared to conventional C-band radar observation. However, it has a tendency to underestimate the rainfall, and the accuracy is not always superior to that of the C-band radar. The accuracy evaluation of the X-band radar observation in this study was conducted using only limited rainfall events, and more cases should be examined for developing a broader understanding of the general behavior of the X-band radar and for improving observation accuracy.

• Journal of the Korean earth science society
• /
• v.40 no.1
• /
• pp.56-67
• /
• 2019

In this study, we analyzed the intensity attenuation for M 6.0, 6.5, and 7.0 earthquakes using the broadband strong ground motion simulation platform based on the physical seismic modeling developed by the US Southern California Earthquake Center (SCEC). The location of the earthquake was assumed to be near the epicenter of the 2016 M 5.8 Gyeongju earthquake, but two of the representative US regional models provided by the SCEC strong ground motion simulation platform were used for the propagation model. One is the Central and Eastern United States (CEUS) model representing the intraplate region, and the other is the LA Basin model representing the interplate region. Five modeling methodologies are presented in the version 16.5 of the simulation platform, and Song and Exsim models were used in this study. In the analysis, we found that different intensity attenuation patterns can be observed with the same magnitude of earthquakes, especially depending on the region (CEUS vs LA Basin). Given the same magnitude and distance, the instrumental intensity in the CEUS region (intraplate) could be larger by a unit of 2 than that in the LA Basin region (interplate). Given the difference of intensity attenuation patterns observed in the study, it is important to know the regional intensity attenuation characteristics to understand the accurate level of seismic hazard imposed in the Korean Peninsula. This study also shows the level of the uncertainty of intensity attenuation if region specific attenuation characteristics are not considered.

• International Journal of Ocean System Engineering
• /
• v.2 no.4
• /
• pp.223-232
• /
• 2012

For the accurate estimation of the position and orientation of a UUV (unmanned underwater vehicle), a low-cost AHRS (attitude heading reference system) was developed using a low-cost IMU (inertial measurement unit) sensor which provides information on the 3D acceleration, 3D turning rate and 3D earth-magnetic field data in the object coordinate system. The main hardware system is composed of an IMU sensor (ADIS16405) and TMS320F28335, which is coded with an extended kalman filter algorithm with a 50-Hz sampling frequency. Through an experimental gimbal device, good estimation performance for the pitch, roll, and yaw angles of the developed AHRS was verified by comparing to those of a commercial AHRS called the MTi system. The experimental results are here presented and analyzed.

• Journal of applied mathematics & informatics
• /
• v.10 no.1_2
• /
• pp.193-207
• /
• 2002

The present investigation deals with the pulsatile flow of incompressible viscous fluid through a circular rigid tube provided with constriction. The method applied here is the Decomposition Method, which has been developed by George Adomian [3]. The advantages of this method are the avoidance of simplifications and restrictions, which change the non-linear problem to mathematically tractable one, whose solution is not consistent with physical solution. Theoretically results, such as, wall shear stress and axial velocity component, have been obtained and the graphical solutions of these theoretical results have been shown in the figures.