Observation of the Degradation Characteristics and Scale of Unevenness on Three-dimensional Artificial Rock Joint Surfaces Subjected to Shear     

Eun-Soo Hong  Tae-Hyuk Kwon  Ki-Il Song  Gye-Chun Cho 《Rock Mechanics and Rock Engineering》2016,49(1):3-17

The present study explores the degradation characteristics and scale of unevenness (small-scale roughness) on sheared rock joint surfaces at a low-stress regime. While the degradation characteristics of unevenness and the normal stress are mutually interrelated, an understanding of the degradation patterns of the three-dimensional roughness of rock joints is one of the important components needed to identify asperity failure characteristics and to quantify the role of damaged unevenness in establishing a shear strength model. A series of direct shear tests was performed on three-dimensional artificial rock joint surfaces at different normal stress levels. After shearing, the spatial distributions and statistical parameters of degraded roughness were analysed for the different normal stress levels. The length and area of the degraded zones showed bell-shaped distributions in a logarithmic scale, and the dominant scale (or the most frequently occurring scale) of the damaged asperities (i.e., unevenness) ranged from approximately, 0.5 to 5.0 mm in length and 0.1–10 mm² in area. This scale of the damaged unevenness was consistent regardless of the level of normal stress. It was also found that the relative area of damaged unevenness on a given joint area, and thus the contribution of the mechanical asperity failure component to shear strength increased as normal stress increased.  相似文献   

Evaluating the impacts of fine-scale capillary heterogeneity and wettability on the behavior of buoyancy-driven CO<Subscript>2</Subscript> migration and trapping mechanisms     

Sung Soo Park  Tae Hong Kim  Moon Sik Jeong  Kun Sang Lee 《Environmental Earth Sciences》2016,75(7):550

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Global parameter estimation of the Cochlodinium polykrikoides model using bioassay data     

CHO Hong-Yeon  PARK Kwang-Soon  KIM Sung 《海洋学报(英文版)》2016,35(2):39-45

Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide(a.k.a algal bloom) model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%–50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly required.As opposed to the bioassay data, it is necessary because the bioassay data have limitations in terms of the in-situ coastal conditions.  相似文献   

Tsunami research in Korea     

Choi  Byung-Ho  Cho  Yong-Sik  Yoon  Sung Bum 《Natural Hazards》2016,84(2):437-454

The tsunamis that have occurred in many places around the world over the past decades have taken a heavy toll on human lives and property. The eastern coast of the Korean Peninsula is not safe from tsunamis and has sustained tsunami damage in the past. The aim of this study is to review the past, present, and future of some aspects of tsunami research in Korea. A composite numerical model comprising propagation and inundation models is described. The paper also covers tsunami mitigation efforts in Korea, and a tsunami hazard map is developed and introduced.  相似文献   

Metagenomic characterization of viral communities in Goseong Bay,Korea     

Jinik Hwang  So Yun Park  Mirye Park  Sukchan Lee  Yeonhwa Jo  Won Kyong Cho  Taek-Kyun Lee 《Ocean Science Journal》2016,51(4):599-612

In this study, seawater samples were collected from Goseong Bay, Korea in March 2014 and viral populations were examined by metagenomics assembly. Enrichment of marine viral particles using FeCl₃ followed by next-generation sequencing produced numerous sequences. De novo assembly and BLAST search showed that most of the obtained contigs were unknown sequences and only 0.74% of sequences were associated with known viruses. As a result, 138 viruses, including bacteriophages (87%), viruses infecting algae and others (13%) were identified. The identified 138 viruses were divided into 11 orders, 14 families, 34 genera, and 133 species. The dominant viruses were Pelagibacter phage HTVC010P and Roseobacter phage SIO1. The viruses infecting algae, including the Ostreococcus species, accounted for 9.4% of total identified viruses. In addition, we identified pathogenic herpes viruses infecting fishes and giant viruses infecting parasitic acanthamoeba species. This is a comprehensive study to reveal the viral populations in the Goseong Bay using metagenomics. The information associated with the marine viral community in Goseong Bay, Korea will be useful for comparative analysis in other marine viral communities.  相似文献   

A framework for identifying spatiotemporal hot spots of speculative land transactions using prospective monitoring procedures: the case of South Korea     

Sunghwan Cho  Daejong Kim 《制图学和地理信息科学》2016,43(3):223-232

Abnormally high-priced transactions in urban land speculation bring detrimental effects on economy, environment, and society. Governmental agencies around the world are striving hard to monitor and control land speculation by introducing various policy objectives and tools for an efficient urban development planning. One of the major challenges in controlling land speculation is to quickly identify the spatiotemporal locations of concern (hot spots) by monitoring the spatial clustering pattern changes over time and to alert the appropriate decision-making agencies for timely policy intervention. In this paper, we introduce a framework to rapidly detect the spatiotemporal hot spots of speculative land transactions in near-real-time data by exploiting the prospective monitoring procedures. We applied this method in the city of Hwasung, Republic of Korea, as an empirical illustration and found that the locations Jeongnam, Bongdam, Mado, and Dongtan were identified as hot spots with high, concentrated transaction values. The results indicate that the proposed framework is a capable tool for capturing prospective temporal indicators and pinpointing the localities of land speculation.  相似文献   

The variation of solar proton energy spectra and size distribution with heliolongitude   总被引：2，自引：0，他引：2  

M. A. I. Van Hollebeke  L. S. Ma Sung  F. B. McDonald 《Solar physics》1975,41(1):189-223

A statistical study of the initial phases of 185 solar particle events has been carried out using the data from the Goddard cosmic ray experiments on IMPs IV and V. Special emphasis is placed on the identification of the associated solar flare. The parent flare can be determined for 68 % of the events. It appears probable that most of the unidentified increases occur on the non-visible disc of the Sun. The existence of a preferred-connection longitude between 20°W and 80° W is established by examining the heliolongitude of all the flare associated events. While power law in differential kinetic energy appears to give the best representation it cannot be distinguished from exponential in rigidity over the limited range of 20–80 MeV. It is argued that for heliolongitudes = 20–80°W, _p ,the spectral index determined at the time of maximum particle intensity is representative of the source spectra. For these heliolongitudes _p displays a surprisingly small range with magnitudes varying mainly between 2.0 and 3.1. At lower energies _p is smaller. Previous electron measurements provide almost identical average values of the source spectra over similar energy ranges. These results are discussed briefly in terms of Fermi acceleration models.For flare events located further away from the nominal field line connecting the Earth and the Sun, _p becomes progressively steeper. The lower energies (4–20 MeV) do not exhibit this behavior. It is argued that this spectral steepening at the higher energies is the result of energy-dependent escape during the coronal diffusion process. The size distribution can be represented by a power law of the form dN/dI=I ^- where N is the number of events per unit intensity and I is the maximum particle intensity at a given energy (usually taken at 40 MeV) with 1.15 ±0.1. The same value of a applies to both eastern and western hemisphere events. The event size, on the average, appears to decrease approximately two orders of magnitude for each 60° away from the preferred connection region.Also: Dept. of Physics and Astronomy, University of Maryland, College Park, Md., U.S.A.  相似文献   

Genomic cloning and expression of vitellogenin gene from the self-fertilizing fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae)     

Kim IC  Chang SY  Williams TD  Ja Kim Y  Yoon YD  Lee YS  Park EH  Lee JS 《Marine environmental research》2004,58(2-5):687-691

We cloned the vitellogenin gene from the self-fertilizing fish Rivulus marmoratus, and sequenced 12,326 bp. The number of exons of R. marmoratus and rainbow trout vitellogenin genes were different, and also the splicing junctions are different throughout most of the exons and introns but the amino acid similarity of R. marmoratus vitellogenin gene to other species was rather high. In promoter region of R. marmoratus vitellogenin gene, there were several E2 binding sites and the estrogen response element (ERE). We discuss here the gene structure and expression of R. marmoratus vitellogenin gene.  相似文献   

Internal generation of waves on an arc in a rectangular grid system     

Changhoon Lee  Sung Bum Yoon 《Coastal Engineering》2007

This paper presents a technique to generate waves at oblique angles in finite difference numerical models in a rectangular grid system by using internal generation technique [Lee, C., Suh, K.D., 1998. Internal generation of waves for time-dependent mild-slope equations. Coast. Eng. 34, 35–57.] along an arc-shaped line source. Tests were made for four different types of wave generation layouts. Quantitative experiments were conducted under the following conditions: the propagation of waves on a flat bottom, the refraction and shoaling of waves on a planar slope, and the diffraction of waves to a semi-infinite breakwater. Numerical experiments were conducted using the extended mild-slope equations of Suh et al. [Suh, K.D., Lee, C., Park, W.S., 1997. Time-dependent equations for wave propagation on rapidly varying topography. Coast. Eng. 32, 91–117.]. The fourth layout type consisting of two parallel lines connected to a semicircle showed the best solutions, especially for a small grid size. This technique is useful for the numerical simulation of irregular waves with broad-banded directional spectrum using conventional spectral wave models for the reasonable estimation of bottom friction and wave-breaking.  相似文献   

Hydroelastic response of a very large floating structure over a variable bottom topography   总被引：1，自引：0，他引：1  

Jo Hyun Kyoung  Sa Young Hong  Byoung Wan Kim  Seok Kyu Cho 《Ocean Engineering》2005,32(17-18):2040-2052

An influence of sea-bottom topography on the hydroelastic response of a Very Large Floating Structure (VLFS) is considered. When the floating structure is constructed near the shore, the sea-bottom topographical effect should be considered. In this study, the effect of sea-bottom topography is investigated for four different bottom cases. To calculate the sea-bottom effects rigorously, the finite-element method based on the variational formulation is used in the fluid domain. The pontoon-type floating structure is modeled as the Kirchhoff plate. The mode superposition method is adopted for the hydroelastic behavior of the floating structure.  相似文献