Evaluation of Liquefaction Potential Index Along Western Coast of South Korea Using SPT and CPT     

Min-Woo Seo  Scott M. Olson  Myoung-Hak Oh 《Marine Georesources & Geotechnology》2013,31(3):234-260

For South Korea, liquefaction potential along the western coast has not been widely assessed because South Korea is considered to be a low seismic hazard. However, recent earthquake events and historical records indicate that the seismic hazard of South Korea should not be ignored. Moreover, as artificial fills are extensively used along the western coast for development, liquefaction evaluation of the soils in this area is necessary. In this paper, we present: (1) the seismic characteristics of the study area; (2) procedures for evaluating liquefaction potential, focusing on the liquefaction potential index (LPI) approach; and (3) LPI distributions at several representative locations along the western coast of South Korea under various seismic scenarios. The liquefaction potential index represents the liquefaction potential over the upper 20 m of a boring or sounding. Using cone penetration test (CPT) and standard penetration test (SPT) data from two coastal sites, we compare and discuss CPT-based and SPT-based LPI values, particularly values computed in nonplastic, silt-rich soils. In these soils, it appears that the CPT yields lower liquefaction resistance, resulting in large LPI values. Finally, discussion and suggestions are provided for CPT- and SPT-based liquefaction assessment of low plasticity and high fines content soils.  相似文献   

Understanding of the Common Land Model performance for water and energy fluxes in a farmland during the growing season in Korea   总被引：1，自引：0，他引：1  

Minha Choi  Seung Oh Lee  Hyojung Kwon 《水文研究》2010,24(8):1063-1071

The Common Land Model (CLM) is one of the most widely used land surface models (LSMs) due to the practicality of its simple parameterization scheme and its versatility in embracing a variety of field datasets. The improved assessment of land surface water and energy fluxes using CLM can be an alternative approach for understanding the complex land–atmosphere interactions in data‐limited regions. The understanding of water and energy cycles in a farmland is crucial because it is a dominant land feature in Korea and Asia. However, the applications of CLM to farmland in Korea are in paucity. The simulations of water and energy fluxes by CLM were conducted against those from the tower‐based measurements during the growing season of 2006 at the Haenam site (a farmland site) in Korea without optimization. According to the International Geosphere–Biosphere Programme (IGBP) land cover classification, a homogeneous cropland was selected initially for this study. Although the simulated soil moisture had a similar pattern to that of the observed, the former was relatively drier (at 0·1 m³ m^?3) than the latter. The simulated net radiation showed good agreement with the observed, with a root mean squared error (RMSE) of 41 W m^?2, whereas relatively large discrepancies between the simulation and observation were found in sensible (RMSE of 66 W m^?2) and latent (RMSE of 60 W m^?2) heat fluxes. On the basis of the sensitivity analysis, soil moisture was more receptive to land cover and soil texture parameterizations when compared to soil temperature and turbulent fluxes. Despite the uncertainty in the predictive capability of CLM employed without optimization, the initial performance of CLM suggests usefulness in a data‐limited heterogeneous farmland in Korea. Further studies are required to identify the controls on water and energy fluxes with an improved parameterization. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Effect of the inter-annual variability of rainfall statistics on stochastically generated rainfall time series: part 2. Impact on watershed response variables     

Dongkyun Kim  Francisco Olivera  Huidae Cho  Seung Oh Lee 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(7):1611-1619

This study analyzes how the stochastically generated rainfall time series accounting for the inter-annual variability of rainfall statistics can improve the prediction of watershed response variables such as peak flow and runoff depth. The modified Bartlett–Lewis rectangular pulse (MBLRP) rainfall generation model was improved such that it can account for the inter-annual variability of the observed rainfall statistics. Then, the synthetic rainfall time series was generated using the MBLRP model, which was used as input rainfall data for SCS hydrologic models to produce runoff depth and peak flow in a virtual watershed. These values were compared to the ones derived from the synthetic rainfall time series that is generated from the traditional MBLRP rainfall modeling. The result of the comparison indicates that the rainfall time series reflecting the inter-annual variability of rainfall statistics reduces the biasness residing in the predicted peak flow values derived from the synthetic rainfall time series generated using the traditional MBLRP approach by 26–47 %. In addition, it was observed that the overall variability of the peak flow and run off depth distribution was better represented when the inter-annual variability of rainfall statistics are considered.  相似文献   

Ensemble-based landslide susceptibility maps in Jinbu area, Korea   总被引：2，自引：2，他引：0  

Moung-Jin Lee  Jae-Won Choi  Hyun-Joo Oh  Joong-Sun Won  Inhye Park  Saro Lee 《Environmental Earth Sciences》2012,67(1):23-37

Ensemble techniques were developed, applied and validated for the analysis of landslide susceptibility in Jinbu area, Korea using the geographic information system (GIS). Landslide-occurrence areas were detected in the study by interpreting aerial photographs and field survey data. Landslide locations were randomly selected in a 70/30 ratio for training and validation of the models, respectively. Topography, geology, soil and forest databases were also constructed. Maps relevant to landslide occurrence were assembled in a spatial database. Using the constructed spatial database, 17 landslide-related factors were extracted. The relationships between the detected landslide locations and the factors were identified and quantified by frequency ratio, weight of evidence, logistic regression and artificial neural network models and their ensemble models. The relationships were used as factor ratings in the overlay analysis to create landslide susceptibility indexes and maps. Then, the four landslide susceptibility maps were used as new input factors and integrated using the frequency ratio, weight of evidence, logistic regression and artificial neural network models as ensemble methods to make better susceptibility maps. All of the susceptibility maps were validated by comparison with known landslide locations that were not used directly in the analysis. As the result, the ensemble-based landslide susceptibility map that used the new landslide-related input factor maps showed better accuracy (87.11% in frequency ratio, 83.14% in weight of evidence, 87.79% in logistic regression and 84.54% in artificial neural network) than the individual landslide susceptibility maps (84.94% in frequency ratio, 82.82% in weight of evidence, 87.72% in logistic regression and 81.44% in artificial neural network). All accuracy assessments showed overall satisfactory agreement of more than 80%. The ensemble model was found to be more effective in terms of prediction accuracy than the individual model.  相似文献   

The twentieth century contiguous US temperature changes indicated by daily data and higher statistical moments     

Samuel S. P. Shen  Ai B. Gurung  Hee-S. Oh  T. Shu  David R. Easterling 《Climatic change》2011,109(3-4):287-317

The daily surface air temperature data are used to assess the climate changes of the contiguous United States during the period of 1901 to 2000. The assessment is made through the first four statistical moments of the daily maximum, minimum, and mean temperature anomalies, the linear trends of the moments, and the changes of the anomalies?? probability density functions. The results on the first moment, i.e., the mean, are compared with the existing ones in terms of intra-annual means and their linear trends. Our first moment results agree with known ones and demonstrate a decrease from the 1930s to the 1960s and an increase from the 1970s to 2000. The temperature fluctuation is the smallest in the 1960s among the decades from 1931 to 2000. The trends of the higher (second-, third- and fourth-order) moments of the mean, maximum, and minimum surface air temperatures are calculated for the periods 1901?C2000, 1910?C1945, 1946?C1975, and 1976?C2000. The results show a decreasing trend of the second- and third-order moments of all the temperatures. The fourth-order moments of the mean and maximum surface air temperatures have increasing trends, but that of the minimum surface air temperature has a decreasing trend. The seasonal histograms of the mean, maximum, and minimum surface air temperatures are calculated for the three periods 1910?C1945, 1946?C1975, and 1976?C2000 for the stations which have the largest trend of maximum daily surface air temperature. An obvious change has been identified in the probability density functions. Among the changes of statistical parameters, the ones for the minimum temperature are larger than those for the maximum and mean temperatures.  相似文献   

Possible linkage between East Asian summer drought and North Pacific Oscillation   总被引：1，自引：0，他引：1  

Ki-Seon Choi  Su-Bin Oh  Hi-Ryong Byun  R. H. Kripalani  Do-Woo Kim 《Theoretical and Applied Climatology》2011,103(1-2):81-93

The May North Pacific Oscillation Index and the summer (May and June?CJuly?CAugust??JJA) Effective Drought Index have a strong negative correlation in the East Asian region, particularly in northern China, Korea, and the southwestern regions of Japan (here termed ??Northeast Asia??); this signifies an intensification of the summer drought during positive North Pacific Index (NPI) phase in this region, and the presence of such a phenomenon has been observed in this study. The low-south/high-north anomalous pressure pattern forming in all layers of the troposphere in Northeast Asian region has been a cause of drought. This unusual pressure pattern gives rise to a cold northeasterly and intensifies downward flow and reduces relative humidity. In addition, this cold northeasterly hinders the northward movement of the western North Pacific high and reduces the frequency of tropical cyclones passing through this region, thereby further intensifying drought.  相似文献   

Ecological significance of alkaline phosphatase activity and phosphatase-hydrolyzed phosphorus in the northern part of Gamak Bay, Korea   总被引：1，自引：0，他引：1  

Kwon HK  Oh SJ  Yang HS 《Marine pollution bulletin》2011,62(11):2476-2482

We investigated the ecological significance of alkaline phsophatase (APase) and alkaline phosphatase-hydrolyzable phosphorus (APHP) in the northern part of Gamak Bay, Korea. APase activity was detectable throughout the year, and dissolved inorganic phosphorus (DIP) concentration and APase activity are highly correlated and can be regarded as an indicator of DIP-limiting conditions. Also, a strong linear positive correlation between APase activity and Chl a concentration indicated that the major part of APase activity may have been induced by phytoplanktons. The APHP proportion in dissolved organic phosphorus (DOP) was above ca. 30% from winter to spring and below ca. 15% from summer to autumn due to freshwater discharge and uptake by phytoplankton. APHP may play an important role in species competition in coastal area such as northern part of Gamak Bay where DIP is limiting. Thus, APase induction by phytoplanktons may be ecologically significant, allowing dominance by these organisms under DIP-limiting conditions.  相似文献   

Temperature trends in the skin/surface, mid-troposphere and low stratosphere near Korea from satellite and ground measurements     

Jung-Moon Yoo  Young-In Won  Young-Jun Cho  Myeong-Jae Jeong  Dong-Bin Shin  Suk-Jo Lee  Yu-Ri Lee  Soo-Min Oh  Soo-Jin Ban 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(5):439-455

Various types of satellite (AIRS/AMSU, MODIS) and ground measurements are used to analyze temperature trends in the four vertical layers (skin/surface, mid-troposphere, and low stratosphere) around the Korean Peninsula (123–132°E, 33–44°N) during the period from September 2002 to August 2010. The ground-based observations include 72 Surface Meteorological Stations (SMSs), 6 radiosonde stations (RAOBs), 457 Automatic Weather Stations (AWSs) over the land, and 5 buoy stations over the ocean. A strong warming (0.052 K yr^?1) at the surface, and a weak warming (0.004～0.010 K yr^?1) in the mid-troposphere and low stratosphere have been found from satellite data, leading to an unstable atmospheric layer. The AIRS/AMSU warming trend over the ocean surface around the Korean Peninsula is about 2.5 times greater than that over the land surface. The ground measurements from both SMS and AWS over the land surface of South Korea also show a warming of 0.043～0.082 K yr^?1, consistent with the satellite observations. The correlation average (r = 0.80) between MODIS skin temperature and ground measurement is significant. The correlations between AMSU and RAOB are very high (0.91～0.95) in the anomaly time series, calculated from the spatial averages of monthly mean temperature values. However, the warming found in the AMSU data is stronger than that from the RAOB at the surface. The opposite feature is present above the mid-troposphere, indicating that there is a systematic difference. Warming phenomena (0.012～0.078 K yr^?1) are observed from all three data sets (SMS, AWS, MODIS), which have been corroborated by the coincident measurements at five ground stations. However, it should also be noted that the observed trends are subject to large uncertainty as the corresponding 95% confidence intervals tend to be larger than the observed signals due to large thermal variability and the relatively short periods of the satellitebased temperature records. The EOF analysis of monthly mean temperature anomalies indicates that the tropospheric temperature variability near Korea is primarily linked to the Arctic Oscillation (AO), and secondarily to ENSO (El Niño and Southern Oscillation). However, the low stratospheric temperature variability is mainly associated with Southern Oscillation and then additionally with Quasi-Biennial Oscillation (QBO). Uncertainties from the different spatial resolutions between satellite data are discussed in the trends.  相似文献   

Immobilization of As and Pb in contaminated sediments using waste resources     

Deok Hyun Moon  Da-Yeon Oh  Mahmoud Wazne  Jeong-Hun Park 《Environmental Earth Sciences》2013,69(8):2721-2729

As and Pb-contaminated sediment obtained from the Nakdong Lake and Yeongsan River in the Republic of Korea was stabilized using a combination of calcined oyster shell (COS), waste cow bone (WCB) and coal mine drainage sludge (CMDS). The effectiveness of the stabilization treatment was evaluated using the Korean Standard Test (KST). The KST tests were performed using 1 N HCl extraction fluid for As and 0.1 N HCl extraction fluid for Pb. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) analyses were performed to investigate the mechanism responsible for As and Pb immobilization upon treatment. The treatment results showed that effective stabilization of As and Pb-contaminated sediment was obtained. Specifically, 10 wt% COS–5 wt% CMDS was the best treatment for As immobilization and 5 wt% COS–5 wt% WCB was the best treatment for Pb immobilization. The COS–WCB treatment outperformed the COS–CMDS treatment in immobilizing Pb in the contaminated sediment. SEM–EDX results indicated that Pb immobilization was strongly associated with Ca, Si, Al and P while As immobilization was strongly associated with Fe and O. Therefore, utilization of COS, WCB and CMDS is beneficial for the stabilization of contaminated sediment.  相似文献   

Effects of natural and calcined poultry waste on Cd, Pb and As mobility in contaminated soil   总被引：1，自引：0，他引：1  

Jung Eun Lim  Mahtab Ahmad  Adel R. A. Usman  Sang Soo Lee  Weon-Tai Jeon  Sang-Eun Oh  Jae E. Yang  Yong Sik Ok 《Environmental Earth Sciences》2013,69(1):11-20

The reuse of waste materials as soil additives could be a welcome development in soil remediation. The mobility of Cd, Pb and As in a contaminated soil was investigated using natural and calcined poultry wastes (eggshell and chicken bone), CaCO₃ and CaO at different application rates (0, 1, 3 and 5 %). The chemical composition accompanied with mineralogical composition indicated that CaCO₃ and CaO were the major components in natural and calcined eggshells, respectively, while hydroxyapatite (HAP) dominated the natural and calcined chicken bones. The results showed that soil pH tended to increase in response to increasing application rates of all soil additives. The effectiveness of the additives in reducing Cd, Pb and As mobility was assessed by means of chemical extractions with 0.1 N HCl for Cd and Pb or 1 N HCl for As, according to Korean Standard Test (KST) method. Both calcined eggshell and chicken bone were equally effective with CaO or CaCO₃ in reducing the concentration of 0.1 N HCl-extractable Cd from 6.17 mg kg^?1 to below warning level of 1.5 mg kg^?1, especially at the highest application rate. The application of calcined eggshell, CaO and CaCO₃ also decreased the concentration of 0.1 N HCl-extractable Pb from 1,012 mg kg^?1 to below warning level of 100 mg kg^?1. The Pb concentration decreased significantly with an increasing application rate of chicken bone, but remained above warning level even at the highest application rate. On the contrary, natural and calcined chicken bones led to a significant increase in the mobility of As when compared with the control soil. These findings illustrate that calcined eggshell in particular is equally effective as pure chemical additives in stabilizing Cd and Pb in a contaminated agricultural soil. The presence of As in metal-contaminated soils should be taken into consideration when applying phosphate-containing materials as soil additives, because phosphate can compete with arsenate on adsorption sites and result in As mobilization.  相似文献