• Korean Journal of Remote Sensing
• /
• v.34 no.1
• /
• pp.101-115
• /
• 2018

The Long Valley area and its surroundings are part of a major volcano system where inflation occurred in the resurgent dome in the 1990s. We used ENVISAT data to monitor surface deformation of the Long Valley area and its surroundings after the inflation, from 2003-2010. To retrieve the time series of the deformation, we applied the refined Small BAseline Subset (SBAS) algorithm which is improved using an iterative approach to minimize unwrapping error. Moreover, ascending and descending data were used to decompose the horizontal and vertical deformation in detail. To confirm refined SBAS results, we used GPS dataset. The InSAR errors are estimated as ${\pm}1.0mm/yr$ and ${\pm}0.8mm/yr$ from ascending and descending tracks, respectively. Compare to the previous study of 1990s over the Long Valley and its surroundings, Paoha Island and CASA geothermal area still subside. The deformation pattern in the Long Valley area during the study period (2003-2010) went through both subsidence (2003-2007) and slow uplift(2007-2010) episodes. Our research also shows no deformation signal near McGee Creek. Our study provided a better understanding of the surface changes of the indicators in the 1990s and 2000s.

• Korean Journal of Geomatics
• /
• v.3 no.1
• /
• pp.1-6
• /
• 2003

The purpose of this study is to make out a history of the coastline deformation with annual aerial photos of the target area and to suggest an efficient method for interpreting the coastline deformation. First, there were difficulties in obtaining annual aerial photos of an identical area as well as collecting periodical datum because of too much change of the real area during more than 27 years. Besides the past aerial photo is inferior to the latest one in quality. So there is nothing but to exclude an accuracy evaluation of the ortho photo. Taken into account the extent of the coastline change for 27 years is more than 10M and the all errors of the ortho image is included in this extent, both an accuracy and an error are ignored. The result of this study show that the coastline in the sea area of Namhangjin maintain advanced forward the ocean and keeps on moving with maintaining fairly wider shape of balance beach. Also The coastline deformation off l㎞ from the estuary is greatly irregular, which means the erosion of the sea in this area is in progress. The latest data being the aerial photo in 1996, it is difficult to find out the current conditions of a coastal erosion. However, considered the construction of a breakwater in Anmok Harbor is going on, the beach erosion becomes more accelerative recently. The aerial photos of the present Namhangjin's situation will make it possible to understand the history of the coastline change more accurately.

• Economic and Environmental Geology
• /
• v.34 no.1
• /
• pp.133-146
• /
• 2001

We report the results of structural field observation and measurement of anisotropy of magnetic susceptibility (AMS) of the diamictitic Hwanggangri Formation distributed in Chungju-Suanbo area of the Okchon Belt, Korea. The outcrops of the Hwanggangri Formation show two types of cleavage in general: slaty cleavage (SI) and crenulation cleavage (5z). 5] cleavage is, however, well observable only in the notheastem (NE) part of study area, while overwhelmed by 52 cleavage in the southwestern (5W) part, indicating stronger later deformation in 5W part of the study area. This partitioning of the study area is corroborated by both IRM and AMS parameters: NE part of the study area is characterized by higher IRM intensity, higher bulk magnetic susceptibility, higher AM5 degree, and by oblate shape of magnetic susceptibility ellipsoid. Their values become drastically lowered toward southwest, and reach to a stable minimum in the whole 5W part of the study area. In addition, degree of both metamorphism and deformation tends to increase gradually from northeast toward southwest and also from northwest toward southeast in the study area. Based on the distribution pattern of the principal axes ( $k_1, k_2, k_3$ axes) of magnetic anisotropy ellipsoids revealed in the NE part of the study area, three episodes of deformation ( $D_1, D_2, D_3$ ) are recognized: D_1$ deformation produced $S_2$ cleavage with NE-5W trend, which is caused by a strong NW-SE tlattening of a coaxial pure shear. $D_2$ deformation produced 5z cleavage characterized by a non-coaxial deformation. It was caused by a ductile or semi-ductile thrusting toward NW and concurrent sinistral shearing along $S_2$ cleavage plane. Lastly, $D_3$ deformation produced tlexural folding of all previous structures with a nearly horizontal NE fold axis. Distribution pattern of the principal axes of magnetic anisotropy ellipsoid from the SW part of the study area, on the other hand, does not show any coherency among sites or samples. We interpret that this dispersed pattern of $k_1, k_2, k_3$ axes together with lower anisotropy strength indicates that magnetic fabrics in the SW part have been disturbed either by a superposition of strong deformation/metamorphism or by a kind of reciprocal strain due to an overlapping of $D_1$ and $D_2$ or by both processes.

• The Journal of the Petrological Society of Korea
• /
• v.12 no.3
• /
• pp.101-109
• /
• 2003

The wavy extinction of quartz can be used as a standard indicator showing the degree of rock deformation. In determine the degree of rock deformation, the intensity of wavy extinction (IWE) of quartz was measured using polarizing microscope, digital camera, and NIH Image program. This method was applied to the granite of Pocheon-Gisanri area, which are divided three type; biotite granite (Gb), garnet biotite granite (Ggb) and two mica granite (Gtm). In this study, measurement of wavy extinction was proceeded Ggb in eastern part and Gb in western part based on the Pocheoneup. The result was that Gb shows low deformation degree below D2, and Ggb represents high deformation degree above D3, generally showing that increasing deformation degree from northwest to southeast in the studied area. It is suggested that the fault which penetrated Ggb in 1/250,000 geological map affected the deformation degree of Ggb.

• The Journal of the Petrological Society of Korea
• /
• v.15 no.2 s.44
• /
• pp.49-59
• /
• 2006

This study clarifies the deformation history of Precambrian metamorphic rocks of Sobaegsan Massif (Wonnam Formation, Pyeonghae granite gneiss, Hada leucogranite gneiss) in Giseong-myeon area, Uljin-gun, Korea. It is based on the geometric and kinematic features and the developing sequence of multi-deformed rock structures. It also reviews the extension of Yecheon Shear Zone and the relative occurrence time of each deformation phase from previous researches. It suggests that the geological structure was formed at least through five phases of deformation after formation of their gneissosity or schistosity. (1) The first phase of deformation took placed under compression of ENE-WSW direction, forming NNW trending regional foliation and very tight isoclinal fold. The general trend of gneissosity or schistosity is inferred to be ENE before the first phase of deformation, being rearranged into NNW by the isoclinal folding. (2) The second phase of deformation formed ENE trending regional foliation and tight, isoclinal, rootless intrafolial folds under compression of NNW-SSE direction [occurrence time: after deposition (Permian age) of Dongsugok Formation, Pyeongan Croup, Janggunbong area]. (3) The third phase of deformation occurred by dextral ductile shearing on the regional foliation, forming stretching lineation of ENE trend and S-C mylonitic structure (after intrusion of Hesozoic homblende granite, Sangunmyeon area-before intrusion of Mesozoic Chunyang granite, Janggunbong area). (4) The fourth phase occurred under (E)NE-(W)SW compression, forming (N)NW trending open fold. (5) The fifth phase took place under N-S compression, forming NNE and NNW trending conjugate strike-slip faults, E-W trending thrust-slip faults, and drag folds related to these fault movements. The deformed structures of fourth and fifth phases result from tectonic movement associated with the developing of the Gyeongsang Basin in Cretaceous age, and it partially rearranged the general ENE trend of the regional foliation in the study area. It also suggests that the Yecheon Shear Zone of E-W trending extends into this area but the ductile shear deformation is weakly developed.

• Transactions of Materials Processing
• /
• v.15 no.4 s.85
• /
• pp.311-318
• /
• 2006

One of the most important quality problems in flat plate leveled from hot rolled coils in cut-to-Iength lines is bowing and cambering when they are cut in small width parts. It is verified analytically and experimentally that residual stress remained in plate is th ε source of the problem. In order to produce low residual stress flat plate from hot rolled coils, the proper conditions of leveling are studied and two things are implemented. One is proper plastic deformation area ratio to reduce residual stress within customer requirement by applying suitable plastic deformation and maintain leveling load within structural strength limit of leveler. The other is maintaining uniform plastic deformation along the width of the plate during leveling. Customer requirement for residual stress is met by applying above 70% of plastic deformation area ratio and uniform deformation along width of coil by adjusting back up rolls according to deformation analysis of work roll and back up roll assembly and leveling tests.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.687-696
• /
• 2005

Safety diagnosis was conducted to evaluate the long-term stability evaluation of power transmission tower of which deformation of the upper structural elements occurred. To assess the cause of the structural deformation, field investigation including BIPS, down-hole test, concrete pile coring and finite element analysis were carried out. From these studies, the major cause of deformation was found due to the heavily fractured layer and weathered soil topography at the pile tip area. The cement-milk grouting method was proposed to reinforce these weak zone around the pile tip area. Also, the increase of cross-section and stiffness for steel members of upper tower structures was suggested. Instrumental monitoring was proposed as well to verify reinforcing effect.

• The Journal of the Petrological Society of Korea
• /
• v.13 no.4
• /
• pp.179-190
• /
• 2004

Precambrian metamorphic rocks of Yeongyang-Uljin area, which is located in the eastern part of Sobaegsan Massif, Korea, are composed of Pyeonghae, Giseong, Wonnam Formations and Hada leuco granite gneisses. These show a zonal distribution of WNW-ESE trend, and are intruded by Mesozoic igneous rocks and are unconformably overlain by Mesozoic sedimentary rocks. This study clarifies the deformation history of Precambrian metamorphic rocks after the formation of gneissosity or schistosity on the basis of the geometric and kinematic features and the forming sequence of multi-deformed rock structures, and suggests that the geological structures of this area experienced at least four phases of deformation i.e. ductile shear deformation, one deformation before that, at least two deformations after that. (1) The first phase of deformation formed regional foliations and WNW-trending isoclinal folds with subhorizontal axes and steep axial planes dipping to the north. (2) The second phase of deformation occurred by dextral ductile shear deformation of top-to-the east movement, forming stretching lineations of E-W trend, S-C mylonitic structure foliations, and Z-shaped asymmetric folds. (3) The third phase deformation formed I-W trending open- or kink-type recumbent folds with subhorizontal axes and gently dipping axial planes. (4) The fourth phase deformation took place under compression of NNW-SSE direction, forming ENE-WSW trending symmetric open upright folds and asymmetric conjugate kink folds with subhorizontal axes, and conjugate faults thrusting to the both NNW and SSE with drag folds related to it. These four phases of deformation are closely connected with the orientation of regional foliation in the Yeongyang-Uljin area. 1st deformation produced regional foliation striking WNW and steeply dipping to the north, 2nd deformation locally change the strike of regional foliation into N-S direction, and 3rd and 4th deformations locally change dip-angle and dip-direction of regional foliation.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.276-285
• /
• 2006

Application of anchored or strutted wall system for the earth retention of excavation works in a populated urban area or a poor soil deposit can be limited due to various restrictions. Since the strut becomes longer in a wide excavation site, the stability of an earth retaining wall is decreased, the wall deformation is increased, and the ground settlement is also increased due to an increased buckling or bending deformation of struts. Especially, in a populated urban area, the installation of anchors can be problematic due to the property line of adjacent structures or facilities. Thus, a new concept of earth retaining system like Self-Supported diaphragm Wall can solve several problems expected to occur during excavation in the urban area. In this study, Numerical analyses of counterfort diaphragm wall was introduced and the monitored data from the site was compared with the original results of numerical analyses. Also, in the case of the deep excavation applied the counterfort diaphragm wall, numerical analyses was performed to predict the wall deformation and the reinforcement to reduce the wall deformation was suggested.

• Nuclear Engineering and Technology
• /
• v.45 no.1
• /
• pp.53-60
• /
• 2013

Bentonite is generally used as a buffer material in high-level radioactive waste disposal facilities and consists of 50% quartz by weight. Quartz strongly affects the behavior of bentonite over very long periods. For this reason, quartz dissolution experiment was performed under high-pressure and high-alkalinity conditions based on the conditions found in a high-level radioactive waste disposal facility located deep underground. In this study, two quartz dissolution experiments were conducted on 1) quartz beads under low-pressure and high-alkalinity conditions and 2) a single quartz crystal under high-pressure and high-alkalinity conditions. Following the experiments, a confocal laser scanning microscope (CLSM) was used to observe the surfaces of experimental samples. Numerical analyses using the finite element method (FEM) were also performed to quantify the deformation of contact area. Quartz dissolution was observed in both experiments. This deformation was due to a concentrated compressive stress field, as indicated by the quartz deformation of the contact area through the FEM analysis. According to the numerical results, a high compressive stress field acted upon the neighboring contact area, which showed a rapid dissolution rate compared to other areas of the sample.