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1.
Jeong Yul Kim Martin G. Lockley Haang Mook Kim Jong-Deock Lim Kyung Soo Kim 《Cretaceous Research》2009,30(6):1387-1397
Twelve trackways of ornithopods from Lower Cretaceous lacustrine margin deposits of the Jindong Formation represent new dinosaur trackways described from Korea. The site, discovered during highway construction, was rescued by removing the most important trackways to the Korean Natural Heritage Center in Daejeon, where they are on permanent display. The new ichnotaxon Ornithopodichnus masanensis ichnogen. et ichnosp. nov. is recognized as a distinctive robust tridactyl track, slightly wider than long (l/w ratio = 0.91), with positive (inward) rotation. The toe prints are very thick, broad and U-shaped, resulting in a trefoil outline with a smoothly rounded hind margin. Digit III is short and projects anteriorly much less than digit II and IV (= weak mesaxony). Divarication of digits II-IV is about 70° with interdigital angle II-III larger than III-IV. Trackway width is narrow and the stride length/track length ratio is about 4.2–4.6. The Ornithopodichnus trackways evidently represent gregarious blunt-toed Iguanodon-like bipedal ornithopods, although poorly preserved manus traces are discerned in a few trackways. Ornithopodichnus is distinct from other well known iguanodontid tracks that display much stronger mesaxony and indicates a polarity in ornithopod foot morphology that can be verified by reference to known foot skeletons. 相似文献
2.
Abstract In a laboratory model ocean, fluid in a rotating tank of varying depth is subjected to “wind-stress”, For a certain range of the parameters, Ekman number E and Rossby number R, a homogeneous fluid displays steady, westward intensified flow. For the same range of E and R, a two-layer fluid can have baroclinic instabilities. The parameter range for the various kinds of instabilities is mapped in a regime diagram. The northward transport in the western boundary current is measured as it varies with Rossby number for both homogeneous and two-layer fluid. 相似文献
3.
National-scale assessment of landslide susceptibility to rank the vulnerability to failure of rock-cut slopes along expressways in Korea 总被引：2，自引：1，他引：1
Jangwon Suh Yosoon Choi Tae-Dal Roh Hyi-Jun Lee Hyeong-Dong Park 《Environmental Earth Sciences》2011,63(3):619-632
The objective of this study is to perform a preliminary national-scale assessment of the landslide susceptibility of rock-cut slopes along expressways in Korea. A geographic information system (GIS) database was compiled based on data from topographical and geological maps, and rock-cut slope data, including the locations of past landslides. Seven factors (i.e., slope height, slope length, slope gradient, upper slope gradient, lithology, distance from nearest fault, and dip direction of slope) were extracted from the GIS database to assess the relationship between each factor and landslide events. Weight of evidence (WOE), analytic hierarchy process (AHP), and fuzzy logic methods, as well as hybrid methods, were used to establish the rating of classes for each factor, weightings for the factors, and to combine multiple factor layers into landslide-susceptibility maps. A comparison of the results obtained using several different methods, based on the area under curve technique, revealed that the WOE method showed the highest accuracy of 74%. The annual cost of traffic congestion resulting from slope failures was evaluated to identify those rock-cut slopes where detailed investigations and landslide warning systems are required. 相似文献
4.
5.
Spatial and Temporal Scale Variations of Sea Surface Temperature in the East Sea Using NOAA/AVHRR Data 总被引：1，自引：0，他引：1
Sea surface temperature fields in the East Sea are composed of various spatial structures such as eddies, fronts, filaments,
turbulent-like features and other mesoscale variations associated with the oceanic circulations of the East Sea. These complex
SST structures have many spatial scales and evole with time. Semi-monthly averaged SST distributions based on extensive satellite
observations of SSTs from 1990 through 1995 were constructed to examine the characteristics of their spatial and temporal
scale variations by using statistical methods of multi-dimensional autocorrelation functions and spectral analysis. Two-dimensional
autocorrelation functions in the central part of the East Sea revealed that most of the spatial SST structures are anisotropic
in the shape of ellipsoids with minor axes of about 90–290 km and major axes of 100–400 km. Two dimensional spatial scale
analysis demonstrated a consistent pattern of seasonal variation that the scales appear small in winter and spring, increase
gradually to summer, and then decrease again until the spring of the next year. These structures also show great spatial inhomogeneity
and rapid temporal change on time scales as short as a semi-month in some cases. The slopes in spectral energy density spectra
of SSTs show characteristics quite similar to horizontal and geostrophic turbulence. Temporal spectra at each latitude are
demonstrated by predominant peaks of one and two cycles per year in all regions of the East Sea, implying that SSTs present
very strong annual and semi-annual variations.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
In this paper, the dynamic response simulation of heavy cargo suspended by a floating crane is performed. The dynamic equations of the motions of the floating crane and the heavy cargo must be considered by the coupled equations because the floating crane and the heavy cargo are connected by wire ropes and provide force and a moment for each other. Hence, the dynamic equations of motion are set up for considering the 6-degrees-of-freedom floating crane and the 6-degrees-of-freedom cargo based on multibody system dynamics. The nonlinear terms in the equations of motion are considered. In addition, the nonlinear hydrostatic force, the linear hydrodynamic force, the wire rope force, and the mooring force are considered as the external forces. Finally, we estimate the motion of the floating crane and the heavy cargo and also calculate the tension of the wire rope between the two. 相似文献
7.
In this study, a new lumped-mass-stick model (LMSM) is developed based on the modal characteristics of a structure such as eigenvalues and eigenvectors. The simplified model, named the "frequency adaptive lumped-massstick model," hasonly a small number of stick elements and nodes to provide the same natural frequencies of the structure and is applied to a nuclear containment building. To investigate the numerical performance of the LMSM, a time history analysis is carried out on both the LMSM and the finite element model (FEM) for a nuclear containment building. A comparison of the results shows that the dynamic responses of the LMSM in terms of displacement and acceleration are almost identical to those of the FEM. In addition, the results in terms of floor response spectra at certain elevations are also in good agreement. 相似文献
8.
The objectives of this study are to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for the remediation
of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC) and to investigate the
mechanisms responsible for TCE degradation in different ZVI-DC configurations. A series of column experiments was conducted
to evaluate the effect of different arrangements of electrodes and ZVI barriers in the column on the TCE removal capacity
(RC). In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive dechlorination
of TCE was improved up to six times with simultaneous application of ZVI and DC compared to that using ZVI only. The most
effective arrangement of electrode and ZVI for TCE removal was the column set with ZVI and a cathode installed at the down
gradient. Based on the electrokinetic study for the column systems with only DC input, single acid front movement could explain
different RCs. An enhanced dechlorination rate of TCE using E2PRB systems, compared to a conventional PRB system, was observed,
and is considered to be attributed to more electron sources: (1) external DC, (2) electrolysis of water, (3) oxidation of
ZVI, (4) oxidation of dissolved Fe2+, (5) oxidation of molecular hydrogen at the cathode, and (6) oxidation of Fe2+ in mineral precipitates. Each of these electron sources was evaluated for their potential influencing the TCE RC through
the electron competition model and energy consumption. A strong correlation between the quantity of electrons generated, RC,
and the energy-effectiveness was found. 相似文献
9.
Although a detailed finite element(FE) model provides more precise results, a lumped-mass stick(LMS) model is preferred because of its simplicity and rapid computational time. However, the reliability of LMS models has been questioned especially for structures dominated by higher modes and seismic inputs. Normally, the natural frequencies and dynamic responses of a LMS model based on tributary area mass consideration are different from the results of the FE model. This study proposes a basic updating technique to overcome these discrepancies; the technique employs the identical modal response, D(t), to the detailed FE model. The parameter D(t) is a time variable function in the dynamic response composition and it depends on frequency and damping ratio for each mode, independent of the structure's mode shapes. The identical response D(t) for each mode is obtained from the frequency adaptive LMS model; the adaptive LMS model which can provide identical modal frequencies as the detailed FE model. Theoretical backgrounds and formulations of the updating technique are proposed. To validate the updating technique, two types of structures(a symmetric straight column and an unsymmetric T-shaped structure) are considered. From the seismic response results including base shear and base moment, the updating technique considerably improves the seismic response accuracy of the tributary area-based LMS model. 相似文献
10.
Sung‐Hoon Ji Yong‐Kwon Koh Kristopher L. Kuhlman Moo Yul Lee Jong Won Choi 《Ground water》2013,51(2):298-304
In a series of field experiments, we evaluate the influence of a small water pressure change on fracture aperture during a hydraulic test. An experimental borehole is instrumented at the Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The target fracture for testing was found from the analyses of borehole logging and hydraulic tests. A double packer system was developed and installed in the test borehole to directly observe the aperture change due to water pressure change. Using this packer system, both aperture and flow rate are directly observed under various water pressures. Results indicate a slight change in fracture hydraulic head leads to an observable change in aperture. This suggests that aperture change should be considered when analyzing hydraulic test data from a sparsely fractured rock aquifer. 相似文献