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Ground Penetrating Radar Imaging of a Circular Patterned Ground near King Sejong Station, Antarctica
( Kwansoo Kim ),( Hyeontae Ju ),( Joohan Lee ),( Changhyun Chung ),( Hyoungkwon Kim ),( Sunjoong Lee ),( Jisoo Kim ) 대한지질공학회 2021 지질공학 Vol.31 No.3
Constraints on the structure and composition of the active layer are important for understanding permafrost evolution. Soil convection owing to repeated moisture-induced freeze-thaw cycles within the active layer promotes the formation of self-organized patterned ground. Here we present the results of ground penetrating radar (GPR) surveys across a selected sorted circle near King Sejong Station, Antarctica, to better delineate the active layer and its relation to the observed patterned ground structure. We acquire GPR data in both bistatic mode (common mid-points) for precise velocity constraints and monostatic mode (common-offset) for subsurface imaging. Reflections are derived from the active layer-permafrost boundary, organic layer-weathered soil boundary within the active layer, and frozen rock-fracture-filled ice boundary within the permafrost. The base of the imaged sorted circle possesses a convex-down shape in the central silty zone, which is typical for the pattern associated with convection-like soil motion within the active layer. The boundary between the central fine-silty domain and coarse-grained stone border is effectively identified in a radar amplitude contour at the assumed active layer depth, and is further examined in the frequency spectra of the near- and far-offset traces. The far-offset traces and the traces from the lower frequency components dominant on the far-offset traces would be associated with rapid absorption of higher frequency radiowave due to the voids in gravel-rich zone. The presented correlation strategies for analyzing very shallow, thin-layered GPR reflection data can potentially be applied to the various types of patterned ground, particularly for acquiring time-lapse imaging, when electric resistivity tomography is incorporated into the analysis.
Kim, Jae-Hyun,Jung, A-Hyun,Jeong, Daun,Choi, Ilsong,Kim, Kwansoo,Shin, Soowon,Kim, Sung June,Lee, Seung-Hee Society for Neuroscience 2016 The Journal of neuroscience Vol.36 No.19
<P>Acetylcholine and noradrenaline are major neuromodulators that affect sensory processing in the cortex. Modality-specific sensory information is processed in defined areas of the cortex, but it is unclear whether cholinergic neurons in the basal forebrain (BF) and noradrenergic neurons in the locus ceruleus (LC) project to and modulate these areas in a sensory modality-selective manner. Here, we mapped BF and LC projections to different sensory cortices of the mouse using dual retrograde tracing. We found that while the innervation of cholinergic neurons into sensory cortices is predominantly modality specific, the projections of noradrenergic neurons diverge onto multiple sensory cortices. Consistent with this anatomy, optogenetic activation of cholinergic neurons in BF subnuclei induces modality-selective desynchronization in specific sensory cortices, whereas activation of noradrenergic LC neurons induces broad desynchronization throughout multiple sensory cortices. Thus, wedemonstrate a clear distinction in the organization and function of cholinergic BF and noradrenergic LC projections into primary sensory cortices: cholinergic BF neurons are highly selective in their projections and modulation of specific sensory cortices, whereas noradrenergic LC neurons broadly innervate and modulate multiple sensory cortices.</P>
Kim, Daeyong,Lee, Myoung-Gyu,Kim, Chongmin,Wenner, Michael L.,Wagoner, Robert H.,Barlat, Frederic,Chung, Kwansoo,Youn, Jae Ryoun,Kang, Tae Jin 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.6
In order to present better prediction capability in computational analysis, mechanical properties of the dualphase high strength steel have been characterized especially for anisotropy as well as the Bauschinger and transient behavior. As for the anisotropy, the non-quadratic anisotropic yield function Yld2000-2d has been utilized and its material parameters have been obtained using the uni-axial tension tests as well as the hydraulic bulge test. To measure the hardening behavior including the Bauschinger and transient behavior, a newly developed test method has been applied for the uni-axial tension/compression and compression/tension tests, in which solid blocks along the both sides of the sheet specimen prevent buckling. From the tension/compression curves, the equations to describe isotropic and kinematic hardening behavior have been obtained. The modified Chaboche model has been confirmed to well represent the hardening behavior including the Bauschinger and transient behavior.
Kwansoo Kim,Donghwan An,Kwangseok Chae 한국농업경제학회 2007 農業經濟硏究 Vol.48 No.4
This paper tests whether exogenous shocks including agricultural policies, trade liberalization and financial crisis have impacts on the structural changes in the farm or farm household income. Unlike previous studies that specify break points prior to the estimation of regression, this paper estimates break points by fitting time series models. Tests for the structural breaks show that there is no structural break in the real farm household income whereas real farm income has five break points. Especially the break at 1997 can be interpreted as the impacts of financial crisis. The break points of 1983, 1987 and 1992 approximately match with the timings of agricultural policies that aimed better structure of agriculture and rural area were implemented. The assessed impacts of exogenous shocks at 1970, 1983, 1987 and 1992 are all positive. However, the assessed impacted of the shock at 1997 is negative. The impacts of the shock at 1997 are assessed within the range between -1,141,432 won and -3,167,804 won.
( Kwansoo Kim ),( Donghwan An ),( Kwangseok Chae ) 한국농업경제학회 2007 KOREAN JOURNAL OF AGRICULTURAL ECONOMICS(KJAT) Vol.48 No.3
This paper tests whether exogenous shocks including agricultural policies, trade liberalization and financial crisis have impacts on the structural changes in the farm or farm household income. Unlike previous studies that specify break points prior to the estimation of regression, this paper estimates break points by fitting time series models. Tests for the structural breaks show that there is no structural break in the real farm household income whereas real farm income has five break points. Especially the break at 1997 can be interpreted as the impacts of financial crisis. The break points of 1983, 1987 and 1992 approximately match with the timings of agricultural policies that aimed better structure of agriculture and rural area were implemented. The assessed impacts of exogenous shocks at 1970, 1983, 1987 and 1992 are all positive. However, the assessed impacted of the shock at 1997 is negative. The impacts of the shock at 1997 are assessed within the range between -1,141,432 won and -3,167,804 won.