Shuenn-Yih Chang  Yu-Chi Sung 《地震工程与工程振动(英文版)》2005,4(1):117-127

It has been well studied that the γ-function explicit method can be effective in providing favorable numerical dissipation for linear elastic systems. However, its performance for nonlinear systems is unclear due to a lack of analytical evaluation techniques. Thus, a novel technique is proposed herein to evaluate its efficiency for application to nonlinear systems by introducing two parameters to describe the stiffness change. As a result, the numerical properties and error propagation characteristics of the γ-function explicit method for the pseudodynamic testing of a nonlinear system are analytically assessed. It is found that the upper stability limit decreases as the step degree of nonlinearity increases; and it increases as the current degree of nonlinearity increases. It is also shown that this integration method provides favorable numerical dissipation not only for linear elastic systems but also for nonlinear systems. Furthermore, error propagation analysis reveals that the numerical dissipation can effectively suppress the severe error propagation of high frequency modes while the low frequency responses are almost unaffected for both linear elastic and nonlinear systems. Supported by: National Science Council, Chinese Taipei, Under Grant No. NSC-92-2211-E-027-015  相似文献   

Accounting seasonal nonstationarity in time series models for short-term ozone level forecast     

Sung Eun Kim  Ashok Kumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(4):241-248

Due to the nonlinear feature of a ozone process, regression based models such as the autoregressive models with an exogenous vector process (ARX) suffer from persistent diurnal behaviors in residuals that cause systematic over-predictions and under-predictions and fail to make accurate multi-step forecasts. In this article we present a simple class of the functional coefficient ARX (FARX) model which allows the regression coefficients to vary as a function of another variable. As a special case of the FARX model, we investigate the threshold ARX (TARX) model of Tong [Lecture notes in Statistics, Springer-Verlag, Berlin, 1983; Nonlinear time series: a dynamics system approach, Oxford University Press, Oxford, 1990] which separates the ARX model in terms of a variable called the threshold variable. In this study we use time of day as the threshold variable. The TARX model can be used directly for ozone forecasts; however, investigation of the estimated coefficients over the threshold regimes suggests polynomial coefficient functions in the FARX model. This provides a parsimonious model without deteriorating the forecast performance and successfully captures the diurnal nonstationarity in ozone data. A general linear F-test is used to test varying coefficients and the portmanteau tests, based on the autocorrelation and partial autocorrelation of fitted residuals, are used to test error autocorrelations. The proposed models were applied to a 2 year dataset of hourly ozone concentrations obtained in downtown Cincinnati, OH, USA. For the exogenous processes, outdoor temperature, wind speed, and wind direction were used. The results showed that both TARX and FARX models substantially improve one-day-ahead forecasts and remove the diurnal pattern in residuals for the cases considered.  相似文献   

Marine resource economics     

James Barney Marsh  Sung Chul Chung 《GeoJournal》1988,16(3):245-246

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Phanerozoic high-pressure eclogite and intermediate-pressure granulite facies metamorphism in the Gyeonggi Massif, South Korea: Implications for the eastward extension of the Dabie–Sulu continental collision zone     

Sung Won Kim  Chang Whan Oh  Ian S. Williams  Daniela Rubatto  In-Chang Ryu  V.J. Rajesh  Cheong-Bin Kim  Jinghui Guo  Mingguo Zhai 《Lithos》2006,92(3-4):357-377

Petrological analysis, zircon trace element analysis and SHRIMP zircon U–Pb dating of retrogressed eclogite and garnet granulite from Bibong, Hongseong area, SW Gyeonggi Massif, South Korea provide compelling evidence for Triassic (231.4 ± 3.3 Ma) high-pressure (HP) eclogite facies (M1) metamorphisms at a peak pressure–temperature (P–T) of ca. 16.5–20.0 kb and 775–850 °C. This was followed by isothermal decompression (ITD), with a sharp decrease in pressure from 20 to 10 kb and a slight temperature rise from eclogite facies (M1) to granulite facies (M2), followed by uplift and cooling. Granitic orthogneiss surrounding the Baekdong garnet granulite and the ophiolite-related ultramafic lenticular body near Bibong records evidence for a later Silurian (418 ± 8 Ma) intermediate high-pressure (IHP) granulite facies metamorphism and a prograde P–T path with peak P–T conditions of ca. 13.5 kb and 800 °C. K–Ar ages of biotite from garnet granulites, amphibolites, and granitic orthogneisses in and around the Bibong metabasite lenticular body are 208–219 Ma, recording cooling to about 310 °C after the Early Triassic metamorphic peak. Neoproterozoic zircon cores in the retrogressed eclogite and granitic orthogneiss provide evidence that the protoliths of these rocks were  800 and  900 Ma old, respectively, similar to the ages of tectonic episodes in the Central Orogenic Belt of China. This, and the evidence for Triassic HP/UHP metamorphism in both China and Korea, is consistent with a regional tectonic link within Northeast Asia from the time of Rodinia amalgamation to Triassic continent–continent collision between the North and South China Blocks, and with an eastward extension of the Dabie–Sulu suture zone into the Hongseong area of South Korea.  相似文献   

Assessment of tributyltin contamination in a shipyard area using a mussel transplantation approach     

Kim NS  Shim WJ  Yim UH  Ha SY  Park PS 《Marine pollution bulletin》2008,57(6-12):883-888

Mussels (Mytilus galloprovincialis) were transplanted to seven stations around a large shipyard for 126 days to evaluate tributyltin (TBT) contamination. Although the application of TBT-based paints to ships is totally banned in Korea, butyltin compounds were found to accumulate in mussels following transplantation. Concentrations of TBT and total butyltins in transplanted mussels near the shipyard were in the range of 40-350 ng Sn/g and 74-530 ng Sn/g on a dry weight basis, respectively. Obviously, low TBT concentrations (6.0-53 ng Sn/gdw) were determined in mussels at four stations outside the shipyard. A negative gradient of TBT concentrations and TBT portion to total butyltin concentrations were found in both the surface water and transplanted mussels according to distance from the shipyard. In addition, TBT concentrations in surface water and transplanted mussels showed significant correlation (r(2) = 0.71; p < 0.001). These results indicate that the shipyard still releases fresh TBT into surrounding waters even after TBT regulation in Korea, and mussel transplantation is useful in evaluating TBT contamination in shipyard area.  相似文献   

由多震相走时和波形作三维地震成像   总被引：1，自引：1，他引：0  

金昭九  李清河  Jung-in Lee  Ho Sung Jang 《CT理论与应用研究》2000,9(4):44-47

本项成果包括：提出天然地震走时反演层析成像技术,采用下列方法使得处理结果得以改善：１）利用３２个地震,４０４条射线的Ｐｇ,Ｓｇ,Ｐｍ,Ｓｍ,Ｐｎ,Ｓｎ等震相增加约束条件：２）用已有精度较高的人工地震测深化结果作速度约束;３）用波形反演来修改模型,把波源,介质吸收,散射等物理特征集中反映在记录中,把诸多物理量开发出来互为约束,以修改后的模型再作反演,使解的稳定性大大提高;４）采用最优化过程,选择遗传  相似文献   

The evolution of coastal wetland policy in developed countries and Korea   总被引：1，自引：0，他引：1  

Sung Gwi Kim 《Ocean & Coastal Management》2010,53(9):562-569

This paper reviews the evolution of the coastal wetland policy in developed countries, leading to finding 3 eras of development of the coastal wetland policy. Before having recognized the wetland functions and services until 1960s, the economic focus had been prevalent, allowing wetland to be exploited mainly for economic uses. But as the wetland ecosystem functions came to be realized, policies to preserve them had been introduced in developed countries, by which the wetland policy had transited ‘step by step’ from an economic to an ecological focus. Through these steps, developed countries came to have the legal and institutional systems for wetland preservation, mitigation and restoration, and management for the wise and sustainable use in conformity to the international standards such as the Ramsar Convention and others since 1990. Thus, they have reached more complete ecological focus in their wetland management with the increase in relevant socio-cultural activities such as the ecosystem education, ecotourism, etc. Roughly speaking, it led to the 3 ‘eras’: the wetland exploitive era, policy transition era, wetland conservation era. In this vein, Korea also experienced a similar exploitive era of economic focus when wetland conversion had been dominated by agriculture, residence and industry before 1990s. From then till 2005, Korea had experienced sufferings from conflicts arising from large reclamation projects such as those in Shihwa and Saemangum, through which she had spent policy transition era and then began to introduce a new policy of ecological focus as in developed countries. Korea can be described as entering a new era of ecological focus with the introduction of relevant advanced systems such as reinforced 10 year of wetland conversion plan with stricter review and permit system, wetland protected area system, special plan to restore existing reclaimed areas to original wetlands, etc.  相似文献   

Comparison of Intestine Microbiota Between Wild and Farmed Korean Rockfish,Sebastes schlegelii     

Yu  Jihyun  Kang  Min Joo  Kim  Yun Jae  Park  Mi-Jeong  Lim  Jae Kyu  Noh  Choong Hwan  Kang  Sung Gyun  Lee  Hyun Sook  Lee  Jung-Hyun  Kwon  Kae Kyoung 《Ocean Science Journal》2021,56(3):297-306

Ocean Science Journal - The Korean rockfish, Sebastes schlegeli, is most commonly farmed in sea cages along the coast of Korea; however, detailed information on intestinal microbiota regarding this...  相似文献   

Influence of Pressure Change During Hydraulic Tests on Fracture Aperture     

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   

Evaluating the severity of building fires with the analytical hierarchy process,big data analysis,and remote sensing     

Lee  Ching-An  Sung  Yu-Chi  Lin  Yuan-Shang  Hsiao  Gary Li-Kai 《Natural Hazards》2020,103(2):1843-1856

Natural Hazards - This study assessed the severity of building fires in 17 villages that comprise Taishan District, New Taipei City, Taiwan. A literature review was performed to discuss the impact...  相似文献