排序方式： 共有28条查询结果，搜索用时 31 毫秒
1.
Il-Sung Zo Joon-Bum Jee Kyu-Tae Lee Bu-Yo Kim 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(4):405-412
Preliminary analysis with a solar radiation model is generally performed for photovoltaic power generation projects. Therefore, model accuracy is extremely important. The temporal and spatial resolutions used in previous studies of the Korean Peninsula were 1 km × 1 km and 1-h, respectively. However, calculating surface solar radiation at 1-h intervals does not ensure the accuracy of the geographical effects, and this parameter changes owing to atmospheric elements (clouds, aerosol, ozone, etc.). Thus, a change in temporal resolution is required. In this study, one-year (2013) analysis was conducted using Chollian geostationary meteorological satellite data from observations recorded at 15-min intervals. Observation data from the intensive solar site at Gangneung-Wonju National University (GWNU) showed that the coefficient of determination (R²), which was estimated for each month and season, increased, whereas the standard error (SE) decreased when estimated in 15-min intervals over those obtained in 1-h intervals in 2013. When compared with observational data from 22 solar sites of the Korean Meteorological Administration (KMA), R2 was 0.9 or higher on average, and over- or under-simulated sites did not exceed 3 sites. The model and 22 solar sites showed similar values of annual accumulated solar irradiation, and their annual mean was similar at 4,998 MJ m?2 (3.87 kWh m?2). These results show a difference of approximately ± 70 MJ m?2 (± 0.05 kWh m?2) from the distribution of the Korean Peninsula estimated in 1-h intervals and a higher correlation at higher temporal resolution. 相似文献
2.
Bu-Yo Kim Joon-Bum Jee Il-Sung Zo Kyu-Tae Lee 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(1):1-10
Cloud cover information is used alongside weather forecasts in various fields of research; however, ground observation of cloud cover is conducted by human observers, a method that is subjective and has low temporal and spatial resolutions. To address these problems, we have developed an improved algorithm to calculate cloud cover using sky image data obtained with Skyviewer equipment. The algorithm uses a variable threshold for the Red Blue Ratio (RBR), determined from the frequency distribution of the Green Blue Ratio (GBR), to calculate cloud cover more accurately than existing algorithms. To verify the accuracy of the algorithm, we conducted daily, monthly, seasonal, and yearly statistical analyses of human observations of cloud cover, obtained every hour from 0800 to 1700 Local Standard Time (LST) for the entirety of 2012 at the Gangwon Regional Meteorological Administration (GRMA), Korea. A case study compared daily images taken at 1200 LST in each season with pixel images of cloud cover calculated by our improved algorithm. The selected cases yielded a high correlation coefficient of 0.93 with the GRMA data. A monthly case study showed low root mean square errors (RMSEs) and high correlation coefficients (Rs) for December (RMSE = 1.64 tenths and R = 0.92) and August (RMSE = 1.43 tenths and R = 0.91). In addition, seasonal cases yielded a high correlation of 0.9 and 87% consistency within ± 2 tenths for winter and a correlation of 0.83 and 82% consistency for summer, when cases of cloud-free or overcast conditions are frequent. Annual analyses showed that the bias of GRMA and Skyviewer cloud cover data for 2012 was -0.36 tenth, and the RMSE was 2.12 tenths, with the GRMA data showing more cloud cover. Considering that the GRMA and Skyviewer data were gathered at different spatial locations, GRMA and Skyviewer data were well correlated (R = 0.87) and showed a consistency of 80% in their cloud cover data (consistent within ± 2 tenths). 相似文献
3.
Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
4.
Adi Zitrin Tom Broadhurst Keiichi Umetsu Dan Coe Narciso Benítez Begoña Ascaso Larry Bradley Holland Ford James Jee Elinor Medezinski Yoel Rephaeli Wei Zheng 《Monthly notices of the Royal Astronomical Society》2009,396(4):1985-2002
We present an improved strong-lensing analysis of Cl0024+1654 ( z = 0.39) using deep Hubble Space Telescope ( HST )/Advanced Camera for Surveys (ACS)/NIC3 images, based on 33 multiply-lensed images of 11 background galaxies. These are found with a model that assumes mass approximately traces light, with a low-order expansion to allow for flexibility on large scales. The model is constrained initially by the well-known five-image system ( z = 1.675) and refined as new multiply-lensed systems are identified using the model. Photometric redshifts of these new systems are then used to constrain better the mass profile by adopting the standard cosmological relation between redshift and lensing distance. Our model requires only six free parameters to describe well all positional and redshift data. The resulting inner mass profile has a slope of d log M /d log r ≃−0.55 , consistent with new weak-lensing measurements where the data overlap, at r ≃ 200 kpc/ h 70 . The combined profile is well fitted by a high-concentration Navarro, Frenk & White (NFW) mass profile, C vir ∼ 8.6 ± 1.6 , similar to other well-studied clusters, but larger than predicted with standard Λ cold dark matter (ΛCDM). A well-defined radial critical curve is generated by the model and is clearly observed at r ≃ 12 arcsec, outlined by elongated images pointing towards the centre of mass. The relative fluxes of the multiply-lensed images are found to agree well with the modelled magnifications, providing an independent consistency check. 相似文献
5.
Finding the strike direction of fractures using GPR 总被引：3，自引：0，他引：3
Soon Jee Seol Jung-Ho Kim † Yoonho Song‡ Seung-Hwan Chung§ 《Geophysical Prospecting》2001,49(3):300-308
GPR reflection energy varies with antenna orientation relative to the strike and dip of the reflector. This directional dependence of GPR responses was investigated through numerical experiments and was used to estimate the azimuth of fractures and joints. Three antenna configurations were considered in this study: perpendicular-broadside (YY mode), parallel-broadside (XX mode) and cross-polarization (YX mode). The reflection energy in the cross-polarization mode shows a shape characteristic similar to the strike, regardless of the dip angle. Those in the other two modes show quite different amplitudes from the strike, depending on the dip angle. We have developed a strike-direction-finding scheme using data obtained from the three different modes for the same survey line. The azimuth angle of each reflector was displayed in colour on the GPR profile. This scheme was applied to a field survey at a granite quarry in southern Korea. The GPR profiles showed different images of the reflectors depending on the antenna configuration. The estimated azimuths of reflectors obtained using our scheme matched fairly well with those of known fractures and joints. 相似文献
6.
7.
Junboum Park Cumaraswamy Vipulanandan Jee Woong Kim Myoung Hak Oh 《Environmental Geology》2006,49(7):977-989
Biosurfactants are frequently used in petroleum hydrocarbon and dense non-aqueous phase liquids (DNAPLs) remediation. The
applicability of biosurfactant use in clayey soils requires an understanding and characterization of their interaction. Comprehensive
effects of surfactants and electrolyte solutions on kaolinite clay soil were investigated for index properties, compaction,
strength characteristics, hydraulic conductivities, and adsorption characteristics. Sodium dodecyl sulfate (SDS) and NaPO3 decreased the liquid limit and plasticity index of the test soil. Maximum dry unit weights were increased and optimum moisture
contents were decreased as SDS and biosurfactant were added for the compaction tests for mixtures of 30% kaolinite and 70%
sand. The addition of non-ionic surfactant, biosurfactant, and CaCl2 increased the initial elastic modulus and undrained shear strength of the kaolinite–sand mixture soils. Hydraulic conductivities
were measured by fixed-wall double-ring permeameters. Results showed that the hydraulic conductivity was not significantly
affected, but slightly decreased from 1×10−7 cm/s (water) to 0.3×10−7 cm/s for Triton X-100 and SDS. The adsorption characteristics of the chemicals onto kaolinite were also investigated by developing
isotherm curves. SDS adsorbed onto soil particles with the strongest bonding strength of the fluids tested. Correlations among
parameters were developed for surfactants, electrolyte solutions, and clayey soils. 相似文献
8.
Jae Seong Lee Eun-Soo Kim Sung-Hyun Kahng Seok-Hyun Yoon Jin-Hyung Cho Kyung-Soo Bahk Dong-Jin Kang 《Ocean Science Journal》2012,47(4):489-495
We have developed a novel miniature in situ microprofiler (NAFRI BelpI) for coastal and deep-sea studies. The BelpI can carry up to three oxygen microsensors, and it allows for simultaneous replicate measurements in a relatively small area. All functions can be controlled and programmed via a small magnetic bar and three reed switches; this feature facilitates the initial setup both onboard and underwater. The large LCD window shows basic information such as the movement intervals of the linear stage, number of replicate measurements, waiting time between measurements, and the pA from the microsensors. From high-resolution vertical profiles of oxygen in coastal sediment measured using the microsensors, the diffusivity boundary layer thicknesses was determined to be in the range 0.30–0.35 mm. In addition, the time-series measurement of oxygen profiles in permeable sandy sediment showed advective transport of oxygen into pore water by tidal agitation. Two examples of in situ measurement using a BelpI suggest that it can be widely applied to the study of the sediment-water interface. 相似文献
9.
This paper presents a case history of geotextile-reinforced dry cover placement on a reclaimed clay deposit treated by progressive trenching method. In order to investigate the effects of the cover material's characteristic of ensuring trafficability with respect to bearing failure and ground deformation, two types of covers were considered in pilot tests: a layer of weathered granite soil cover and a layer of weathered granite soil over stiff crushed stone. A number of in-situ plate load tests were conducted for various cover conditions to assess the bearing capacity of the reclaimed deposit and to determine the thickness and material compositions that satisfy the bearing capacity requirement. In full-scale pilot tests for cover placement, field monitoring was carried out for the surface settlement and pore pressure that developed in the reclaimed clay layer. The results of plate-loading tests and monitoring during staged cover placements are discussed and compared using numerical predictions obtained from both finite element analyses and undrained stability analyses. The comparison results showed that the drainage condition of the ground surface facing the dry cover is strongly related to the ground response and stability. 相似文献
10.
Hyerin Kim Sung-Hyun Cho Dongguen Lee Youn-Young Jung Young-Hee Kim Dong-Chan Koh Jeonghoon Lee 《Environmental Earth Sciences》2017,76(2):82
For water resources management, many studies for investigating flow paths from rainfall to subsurface have been conducted for last half century. A hydrograph separation based on end member mixing was carried out to evaluate the importance of the hydrological pathways providing the main sources of a small granitic watershed, Dorim-cheon, Seoul. An analysis of chloride, oxygen-18 and deuterium isotopes from precipitation and stream water during three storms was conducted with high-resolution data using 129 samples. Stream water, collected in advance of rain event, was assumed as a pre-event water (baseflow) component according to its dry condition and isotopic values compared with the values of different time periods. The contribution from vadose water was ignored due to the thin soil layer covering the study area. Using a two-component mixing model, hydrograph separation of the stream water in Dorim-cheon was conducted based on weighted mean values of rain water and pre-event water component with the high-resolution datasets. As a result of the analysis with water isotopes, contribution of groundwater was dominant during the entire study period (73–74%) except of instant dominance of rainfall at the earliest period. Using chloride as a tracer for hydrograph separation, a significant difference for the amount of pre-event water contribution was identified. This might be caused by the large variation of chloride concentration during the rain event and the end member determination. 相似文献