Assessment of soil loss in South Korea based on land-cover type     

Chunhwa Jang  Yongchul Shin  Donghyuk Kum  Rogyoung Kim  Jay E. Yang  Sung Chul Kim  Sang Il Hwang  Kyoung Jae Lim  Jeong-Ki Yoon  Youn Shik Park  Younghun Jung 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(8):2127-2141

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Practically Applicable Central Limit Theorem for Spatial Statistics     

Byeong U. Park  Tae Yoon Kim  Jeong-Soo Park  S. Y. Hwang 《Mathematical Geosciences》2009,41(5):555-569

Let {Z(s):s∈D⊆ℝ ^d } be a zero mean stationary random field observed at a finite number of locations. Lahiri (Sankhya Ser. A 65:356–388, 2003) proved spatial central limit theorems (CLT) for ∑ _i=1 ⁿ Z(s _i ) assuming a ‘nearly infill domain sampling’. Applications of his results depended on the underlying spatial sampling region and the design in a complicated fashion. The main objective of this paper is to provide CLTs that could be applied easily in practice. We present two main results assuming a ‘nearly infill domain sampling’ defined mainly in terms of dependence. Theorem 1 establishes a CLT for ∑ _i=1 ⁿ Z(s _i ) and Theorem 2 is obtained mainly for applications to density estimates. We report on a simulation study for illustrating a way of applying our results in practice.  相似文献   

Field measurements for calibration of simplified models of the stiffening effect of infill masonry walls in high-rise RC framed and shear-wall buildings     

Zhou  Yun  Pei  Yilin  Zhou  Yi  Hwang  Hyeon-Jong  Yi  Weijian 《地震工程与工程振动(英文版)》2020,19(1):87-104

As a type of nonstructural component, infill walls play a significant role in the seismic behavior of high-rise buildings. However, the stiffness of the infill wall is generally either ignored or considered by simplified empirical criteria that lead to a period shortening. The difference can be greatly decreased by using a structural identification methodology. In this study, an ambient vibration test was performed on four on-site reinforced concrete high-rise buildings, and the design results were compared with the PKPM models using corresponding finite element(FE) models. A diagonal strut model was used to simulate the behavior of the infill wall, and the identified modal parameters measured from the on-site test were employed to calibrate the parameters of the diagonal strut in the FE models. The SAP2000 models with calibrated elastic modulus were used to evaluate the seismic response in the elastic state. Based on the load-displacement relationship of the infill wall, nonlinear dynamic analysis models were built in PERFORM-3 D and calibrated using the measured modal periods. The analysis results revealed that the structural performance under small/large earthquake records were both strengthened by infill walls, and the contribution of infill walls should be considered for better accuracy in the design process.  相似文献   

Empirical formula for fundamental vibration periods of reinforced concrete buildings in Taiwan     

Li‐Ling Hong  Woei‐Luen Hwang 《地震工程与结构动力学》2000,29(3):327-337

More than 30 buildings around Taiwan have been selected to monitor the floor responses under seismic excitation. The structural array monitoring system in each building controls at most 27 channels of accelerometers distributed in several floors. Those buildings were triggered by many events during the past five years of operation. In each building, the records at the basement can be considered as the ground excitation, and the others at the upper floors are the structural responses. The frequency transfer functions of those buildings can be identified by ARX models, and then the fundamental vibration periods are estimated. The identified fundamental vibration periods using different events are compared in order to ensure the reliability of system identification. An empirical formula in predicting the fundamental vibration period is presented through the regression analysis to the identified fundamental vibration periods of 21 reinforced concrete (RC) moment‐resisting frame (MRF) buildings. It is found that the height of a building plays an important role in predicting the fundamental vibration period, compared with the length, width, and time after completion of the building. It is also found that the RC MRF buildings in Taiwan tend to be stiffer than those in the U.S. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Dynamics of particle export on the Northwest Atlantic margin     

Jeomshik Hwang  Steven J. Manganini  Daniel B. Montluon  Timothy I. Eglinton 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(10):1792-1803

The Northwest Atlantic margin is characterized by high biological productivity in shelf and slope surface waters. In addition to carbon supply to underlying sediments, the persistent, intermediate depth nepheloid layers emanating from the continental shelves, and bottom nepheloid layers maintained by strong bottom currents associated with the southward flowing Deep Western Boundary Current (DWBC), provide conduits for export of organic carbon over the margin and/or to the interior ocean. As a part of a project to understand dynamics of particulate organic carbon (POC) cycling in this region, we examined the bulk and molecular properties of time-series sediment trap samples obtained at 968 m, 1976 m, and 2938 m depths from a bottom-tethered mooring on the New England slope (water depth, 2988 m). Frequent occurrences of higher fluxes in deep relative to shallower sediment traps and low Δ¹⁴C values of sinking POC together provide strong evidence for significant lateral transport of aged organic matter over the margin. Comparison of biogeochemical properties such as aluminum concentration and flux, and iron concentration between samples intercepted at different depths shows that particles collected by the deepest trap had more complex sources than the shallower ones. These data also suggest that at least two modes of lateral transport exist over the New England margin. Based on radiocarbon mass balance, about 30% (±10%) of sinking POC in all sediment traps is estimated to be derived from lateral transport of resuspended sediment. A strong correlation between Δ¹⁴C values and aluminum concentrations suggests that the aged organic matter is associated with lithogenic particles. Our results suggest that lateral transport of organic matter, particularly that resulting from sediment resuspension, should be considered in addition to vertical supply of organic matter derived from primary production, in order to understand carbon cycling and export over continental margins.  相似文献   

Recent moon jelly (Aurelia sp.1) blooms in Korean coastal waters suggest global expansion: examples inferred from mitochondrial COI and nuclear ITS-5.8S rDNA sequences     

Ki  Jang-Seu; Hwang  Dae-Sik; Shin  Kyoungsoon; Yoon  Won Duk; Lim  Donghyun; Kang  Young Shil; Lee  Yoon; Lee  Jae-Seong 《ICES Journal of Marine Science》2008,65(3):443-452

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Active exchange of water and nutrients between seawater and shallow pore water in intertidal sandflats     

Dong -Woon Hwang  Guebuem Kim  Han Soeb Yang 《Ocean Science Journal》2008,43(4):223-232

In order to determine the temporal and spatial variations of nutrient profiles in the shallow pore water columns (upper 30 cm depth) of intertidal sandflats, we measured the salinity and nutrient concentrations in pore water and seawater at various coastal environments along the southern coast of Korea. In the intertidal zone, salinity and nutrient concentrations in pore water showed marked vertical changes with depth, owing to the active exchange between the pore water and overlying seawater, while they are temporally more stable and vertically constant in the sublittoral zone. In some cases, the advective flow of fresh groundwater caused strong vertical gradients of salinity and nutrients in the upper 10 cm depth of surface sediments, indicating the active mixing of the fresher groundwater with overlying seawater. Such upper pore water column profiles clearly signified the temporal fluctuation of lower-salinity and higher-Si seawater intrusion into pore water in an intertidal sandflat near the mouth of an estuary. We also observed a semimonthly fluctuation of pore water nutrients due to spring-neap tide associated recirculation of seawater through the upper sediments. Our study shows that the exchange of water and nutrients between shallow pore water and overlying seawater is most active in the upper 20 cm layer of intertidal sandflats, due to physical forces such as tides, wave set-up, and density-thermal gradient.  相似文献   

软件实现的数字视频积分处理器     

黄俊文  刘仁义 《成都信息工程学院学报》1988,(2)

木文从分析气象回波涨落的原因入手,讨论了视频积分处理器参数的选择。从现有硬件实现的数字视频积分器,引导出以全软件实现数字视频积分器的方案。实践证明,软件数字视频积分器与硬件数字视频积分器具有同样的功能,并且具有开发灵活、适用性强的特。点该处理器已经应用在713天气雷达数字化系统中。  相似文献   

西南极利文斯顿岛百耳斯半岛中生代火山岩地球化学特征   总被引：1，自引：0，他引：1  

郑祥身  李钟益 《岩石学报》1998,14(4):503-519

西南极利文斯顿岛百耳斯半岛中生代火山岩是晚侏罗纪至晚白垩纪三期火山活动的产物。岩石普遍贫钾,轻稀土元素略为富集,但轻重稀土分馏不强烈;Ｓｒ、Ｋ、Ｒｂ、Ｂａ、Ｔｈ等大离子亲石元素（ＬＩＬ）明显富集,Ｎｂ和Ｔａ明显亏损,过渡金属族元素Ｃｒ和Ｎｉ强烈亏损,表明它们属于火山弧环境中生成的钙碱性系列岩石。白垩纪中期和白垩纪晚期岩石的８７Ｓｒ／８６Ｓｒ比值主要在０．７０３９～０．７０５３之间变化,εＮｄ＞０,８７Ｓｒ／８６Ｓｒ相对１／Ｓｒ、Ｒｂ、Ｋ和ＳｉＯ２等的变化不大,表明其源区岩浆可能直接来自上地幔,很少受到壳源物质的混染。而晚侏罗纪火山岩的Ｓｒ同位素比值较高,说明早期岩浆可能受到少量地壳物质的混染。但在Ｔｈ／Ｔａ－Ｔｈ和Ｔｈ／Ｓｍ－Ｔｈ图解上所有岩石的投影点分布趋势相同,趋势线的斜率＞０。百耳斯半岛中生代火山岩是上地幔部分熔融生成的同源岩浆不同期的产物  相似文献   

In situ high-pressure synchrotron X-ray powder diffraction study of tunnel manganese oxide minerals: hollandite,romanechite, and todorokite     

Gil Chan Hwang  Jeffrey E. Post  Yongjae Lee 《Physics and Chemistry of Minerals》2015,42(5):405-411

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