• Journal of the Korean earth science society
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• v.44 no.4
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• pp.275-290
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• 2023

Structural inversion refers to the reverse reactivation of extensional faults that influence basin shortening accommodated by contractional faults or folds. On the Korean peninsula, Miocene inversion structures have been found, but the Cretaceous rocks on Geoje Island may have undergone inversion as early as the Upper Cretaceous. To evaluate the structural inversion on Geoje Island, located on the eastern side of South Korea, and to determine the effects of preexisting weakness zones, field-based geometric and kinematic analyses of faults were performed. The lithology of Geoje Island is dominated by hornfelsified shale, siltstone, and sandstone in the Upper-Cretaceous Seongpori formation. NE and NW-oblique normal faults, conjugate strike-slip (NW-sinistral transpressional and E-W-dextral transtensional) faults, and NE-dextral transpressional faults are the most prominent structural features in Geoje Island. Structural inversion on Geoje Island was evidenced by the sinistral and dextral transpressional reactivation of the NW and NE-trending oblique normal faults respectively, under WNW-ESE/NW-SE compression, which was the orientation of the compressive stress during the Late Cretaceous to Early Cenozoic.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.54-57
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• 2007

Recently, multidimensional joint inversion of geophysical data based on fundamentally different physical properties has been actively studied. Joint inversion can provide a way to much more accurately image the subsurface structure. Through the joint inversion, furthermore, it is possible to directly estimate non-geophysical material properties from geophysical measurements. In this study, I derive the objective functions and normal equations of three different joint inversion approaches: one approach based on the structural similarity using cross-gradient, and the other two using the a priori information on the model parameters and the correlation between material properties. Since all the equations derived in this study are based on the same inversion method (smoothness constrained least-squares), it is possible to mix the joint inversion methods so as to produce a new joint inversion algorithm.

• The Journal of Engineering Geology
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• v.28 no.3
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• pp.367-377
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• 2018

This study introduces a DC resistivity inversion method that incorporates structural and inequality constraints to enhance the resolution of resistivity inversions, and presents sample inversion results with these constraints. In the constrained inversions, a base model is constructed from a layered model through interpretation of other geophysical data. Inversion tests establish that both the structural and inequality constraints produce better resistivity models than the unconstrained inversion. However, the inequality inversion not only reproduces the exact layered structure of the background, it reproduces conductive anomalies at a depth of ~ 10 m when an inexact base model of electrical resistivity is used.

• Biomedical Science Letters
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• v.15 no.4
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• pp.363-368
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• 2009

One of the frequent occurrences in rearrangements is chromosome inversion. Pericentric inversion is considered to be the variant of normal karyotype. We investigated the karyotypes of 1195 cases being referred to prenatal diagnosis using standard GTG banding for karyotype preparation. The chromosomal analysis revealed a total of 15 (1.26%) inversions. The characteristics of inversion type [(inv(4), inv(8), inv(9), inv(11)) were investigated on the basis of chromosomal analyses of fetuses and their parents. The results from chromosomal examination of the parents, whose fetuses were diagnosed as inversion, show that either parent might be the carrier. Inversion in human chromosome is commonly seen in normal humans and the frequency estimated to be 1 to 2% in general population and the exact amount of this phenomenon is still unclear. These results indicate that inv(8), inv(9), and inv(11) are phenotypically normal. However these may often cause clinical problems in offspring of the carrier, such as fetal wastage repeated spontaneous abortions and infertility with unknown mechanisms related to sex. We describe an inversion of human chromosome and its clinical correlation with human genetic disease.

• Journal of Environmental Science International
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• v.5 no.4
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• pp.441-451
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• 1996

The surface meteorological and upper layer meteorological observation carried out to investigate influences of sea breeze effect on lower layer atmosphere at Gori nuclear power plant for 29∼30 July, 1996. According to surface meteorological data, the inflow of sea breeze was occurred 11:30 on 29 July, 10:30-on 30 July, respectively, at observation site. And the meteorological tower data showed that wind direction of sea breeze was identified as south-westerly, and wind speed of 58 m was 2 times stronger than that of 10 m. It is notworthy that surface inversion layer which built from the night time to daybreak of next day was not broken off by seab reeze's inflow for daytime, and strong inversion layer observed at 47∼243 m with moderately stable class (F) by URC. It was found that strong stable layer of potential temperature appeared at that layer, maximum relative humidity observed at the bottom of inversion layer and maximum mixing ratio observed in the low of inversion layer.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.223-231
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• 2013

This paper presents a time-domain Gauss-Newton full-waveform inversion method for the material profile reconstruction in heterogeneous semi-infinite solid media. To implement the inverse problem in a finite computational domain, perfectly-matchedlayers( PMLs) are introduced as wave-absorbing boundaries within which the domain's wave velocity profile is to be reconstructed. The inverse problem is formulated in a partial-differential-equations(PDE)-constrained optimization framework, where a least-squares misfit between measured and calculated surface responses is minimized under the constraint of PML-endowed wave equations. A Gauss-Newton-Krylov optimization algorithm is utilized to iteratively update the unknown wave velocity profile with the aid of a specialized regularization scheme. Through a series of one-dimensional examples, the solution of the Gauss-Newton inversion was close enough to the target profile, and showed superior convergence behavior with reduced wall-clock time of implementation compared to a conventional inversion using Fletcher-Reeves optimization algorithm.

• Journal of the Korean Chemical Society
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• v.41 no.3
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• pp.123-129
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• 1997

In order to consider the reduced mass effects on the out-of-plane ring inversion vibration of 1,3-CHD, the vector-based computer program has been written and the kinetic energy expansion function for the large amplitude ring inversion vibration has been calculated using this program. The structural parameters for the calculations have been determined from the ab initio HF/6-31G** calculation. The potential energy function for the out-of-plane ring inversion vibration of 1,3-CHD has been determined from the kinetic energy expansion function and previously reported low-frequency Raman data. The vibrational Hamiltonian calculation including kinetic energy expansion function made it possible to determine the more reliable out-of-plane potential energy function for the ring inversion of 1,3-CHD.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.221-230
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• 2021

This paper proposes full waveform inversion (FWI) for estimating the physical properties of a layered half-space. An FWI solution is obtained using a genetic algorithm (GA), which is a well-known global optimization approach. The dynamic responses of a layered half-space subjected to a harmonic vertical disk load are measured and compared with those calculated using the estimated physical properties. The responses are calculated using the thin-layer method, which is accurate and efficient for layered media. Subsequently, a numerical model is constructed for a layered half-space using mid-point integrated finite elements and perfectly matched discrete layers. An objective function of the global optimization problem is defined as the L2-norm of the difference between the observed and estimated responses. A GA is used to minimize the objective function and obtain a solution for the FWI. The accuracy of the proposed approach is applied to various problems involving layered half-spaces. The results verify that the proposed FWI based on a GA is suitable for estimating the material properties of a layered half-space, even when the measured responses include measurement noise.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.314-321
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• 2007

Recently, multi-dimensional joint inversion of geophysical data based on fundamentally different physical properties is being actively studied. Joint inversion can provide a way to obtaining much more accurate image of the subsurface structure. Through the joint inversion, furthermore, it is possible to directly estimate non-geophysical material properties from geophysical measurements. In this study, we developed a new algorithm for jointly inverting dc resistivity and seismic traveltime data based on the multiple constraints: (1) structural similarity based on cross-gradient, (2) correlation between two different material properties, and (3) a priori information on the material property distribution. Through the numerical experiments of surface dc resistivity and seismic refraction surveys, the performance of the proposed algorithm was demonstrated and the effects of different regularizations were analyzed. In particular, we showed that the hidden layer problem in the seismic refraction method due to an inter-bedded low velocity layer can be solved by the joint inversion when appropriate constraints are applied.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.5
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• pp.213-219
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• 2014

The source parameters of four earthquakes with magnitude larger than 4.0 nearby the offshore Sinan are analyzed. The waveform inversion method is used for analyzing the source parameters of two events (20 August 2012 and 21 April 2013) with C&B and AK135-c crustal velocity structure models. The source parameters of the other two events (26 July 1994 and 23 March 2003) are obtained from references. Focal mechanisms of the events are strike slip faulting or strike slip faulting with a thrust component. The directions of P-axes of the events are ENE-WSW or NE-SW which are similar to previous studies on P-axes in and around the Korean peninsula. With regard to the events nearby the offshore Sinan, the regional stress, rather than being local stress, is seen to be the result of the combination of tectonic forces from the compression of plates colliding to the Eurasian Plate.