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161.
Seong-Hoon Cho Dayton M. Lambert Seung Gyu Kim Roland K. Roberts William M. Park 《Journal of Geographical Systems》2011,13(4):393-414
This research uses a sequence of hedonic spatial regressions for a metropolitan housing market in the Southeastern United
States to explore a new procedure that establishes the relationship between the value attributable to open space and distance
from housing locations (a “distance-decay function”) within a given community. A distance-decay function allows identification
of the range of distance over which open space affects housing values and the estimation of a proxy for the value added to
nearby houses resulting from hypothetical open space preservation. Ex post analyses of the open-space regression coefficients suggest marginal implicit price functions for three types of open space
that decay as open space area increases with respect to house location. After controlling for other factors in the spatial
hedonic model, simple distance-decay functional relationships were established between the implicit prices of developed open
space, forest-land open space, and agriculture-wetland open space and the buffer radius of the open-space areas surrounding
a given housing location. The proposed method may be useful for identifying the range over which preferences for different
types of open space are exhibited. 相似文献
162.
Jae-Hwan Cho Kyung-Rae Dong Yong-Jin Ju Woon-Kwan Chung Seon-Chil Kim Jong-Woong Lee Yong-Soon Park Eun-Jin Choi Ho-Sung Kim Yeong-Cheol Heo Hyon-Chol Jang 《Environmental Earth Sciences》2013,70(4):1515-1523
The purpose of this study was to measure, compare, and analyze the air concentration of radon that was emitted to the atmosphere from construction materials such as cement brick, tile, red clay tile, and gypsum tile. The study method was to use continuous radon monitoring equipment (RTM 1688-2) to measure concentrations of radon and thoron contained in brick, tile, red clay tile, and gypsum tile. According to the measurement results, the cement brick among the four samples showed the highest measurement value for radon, while the red clay tile showed the highest measurement value for thoron. When the radon emission concentration was estimated based on materials required for construction per unit area (3.3 m2) in an actual construction, the cement brick had the highest measurement values for radon and thoron. This study confirmed the degree of radon emission from construction materials. The purpose of this study was also to suggest a method to examine the effects of radon and reduce the dose of personal radiation exposure. It is believed that the government should be active in publicizing and managing use of construction materials that have lower levels of radon emission. 相似文献
163.
Jongchul Chae Hyung-Min Park Kwangsu Ahn Heesu Yang Young-Deuk Park Kyung-Suk Cho Wenda Cao 《Solar physics》2013,288(1):89-103
The characteristics of Doppler shifts in a quiet region of the Sun are compared between the Hα line and the Ca?ii infrared line at 854.2 nm. A small area of 16″×40″ was observed for about half an hour with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory. The observed area contains a network region and an internetwork region, and identified in the network region are fibrils and bright points. We infer Doppler velocity v m from each line profile at each individual point with the lambdameter method as a function of half wavelength separation Δλ. It is confirmed that the bisector of the spatially averaged Ca?ii line profile has an inverse C-shape with a significant peak redshift of +?1.8 km?s?1. In contrast, the bisector of the spatially averaged Hα line profile has a C-shape with a small peak blueshift of ??0.5 km?s?1. In both lines, the bisectors of bright network points are significantly redshifted not only at the line centers, but also at the wings. The Ca?ii Doppler shifts are found to be correlated with the Hα ones with the strongest correlation occurring in the internetwork region. Moreover, we find that here the Doppler shifts in the two lines are essentially in phase. We discuss the physical implications of our results in view of the formation of the Hα line and Ca?ii 854.2 nm line in the quiet region chromosphere. 相似文献
164.
Jinwoong Kim Hyun Mee Kim Chun-Ho Cho 《Asia-Pacific Journal of Atmospheric Sciences》2014,50(3):327-344
To estimate the surface carbon flux in Asia and investigate the effect of the nesting domain on carbon flux analyses in Asia, two experiments with different nesting domains were conducted using the CarbonTracker developed by the National Oceanic and Atmospheric Administration. CarbonTracker is an inverse modeling system that uses an ensemble Kalman filter (EnKF) to estimate surface carbon fluxes from surface CO2 observations. One experiment was conducted with a nesting domain centered in Asia and the other with a nesting domain centered in North America. Both experiments analyzed the surface carbon fluxes in Asia from 2001 to 2006. The results showed that prior surface carbon fluxes were underestimated in Asia compared with the optimized fluxes. The optimized biosphere fluxes of the two experiments exhibited roughly similar spatial patterns but different magnitudes. Weekly cumulative optimized fluxes showed more diverse patterns than the prior fluxes, indicating that more detailed flux analyses were conducted during the optimization. The nesting domain in Asia produced a detailed estimate of the surface carbon fluxes in Asia and exhibited better agreement with the CO2 observations. Finally, the simulated background atmospheric CO2 concentrations in the experiment with the nesting domain in Asia were more consistent with the observed CO2 concentrations than those in the experiment with the nesting domain in North America. The results of this study suggest that surface carbon fluxes in Asia can be estimated more accurately using an EnKF when the nesting domain is centered in Asian regions. 相似文献
165.
Dongkyun Kim Francisco Olivera Huidae Cho 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(7):1601-1610
A noble approach of stochastic rainfall generation that can account for inter-annual variability of the observed rainfall is proposed. Firstly, we show that the monthly rainfall statistics that is typically used as the basis of the calibration of the parameters of the Poisson cluster rainfall generators has significant inter-annual variability and that lumping them into a single value could be an oversimplification. Then, we propose a noble approach that incorporates the inter-annual variability to the traditional approach of Poisson cluster rainfall modeling by adding the process of simulating rainfall statistics of individual months. Among 132 gage-months used for the model verification, the proportion that the suggested approach successfully reproduces the observed design rainfall values within 20 % error varied between 0.67 and 0.83 while the same value corresponding to the traditional approach varied between 0.21 and 0.60. This result suggests that the performance of the rainfall generation models can be largely improved not only by refining the model structure but also by incorporating more information about the observed rainfall, especially the inter-annual variability of the rainfall statistics. 相似文献
166.
This study investigated localized responses, such as circumferential stresses, on corrugation and pipe deflections. Also, this study examined the effect of corrugation geometry on the overall and localized response of corrugated pipes with refined three‐dimensional modeling of the entire soil–pipe interaction system, including corrugation. To investigate the availability of the traditional two‐dimensional method, the results from the three‐dimensional finite element method (FEM) were compared with those from the two‐dimensional FEM. The soil–pipe modeling techniques of this study were verified by comparing the FEM results by Utah State University and analytical results. An artificial neural network (ANN)‐based model to predict vertical deflections of buried corrugated pipes was developed to overcome the shortcomings of existing methods and obtain results that are close to the level of accuracy of FEM results. In order to train an ANN, analyses on a large amount of data were executed with various standardized pipe geometries and burial depths regulated by the Korea Highway Corporation using the two‐dimensional FEM verified in this study. The widely used back propagation algorithm was adopted. The ANN‐based model developed in this study was shown to be an effective tool by comparing the results with test data and sensitivity analyses were executed based on the data from the developed ANN. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
167.
A comparative study of the adaptive choice of thresholds in extreme hydrologic events 总被引:1,自引:1,他引:0
Myoung-Jin Um Woncheol Cho Jun-Haeng Heo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):611-623
In the hydrologic analysis of extreme events such as precipitation or floods, the data can generally be divided into two types:
partial duration series and annual maximum series. Partial duration series analysis is a robust method to analyze hydrologic
extremes, but the adaptive choice of an optimal threshold is challenging. The main goal of this paper was to determine the
best method for choosing optimal thresholds. Ten semi-parametric tail index estimators were applied to find the optimal threshold
of a 24-h duration precipitation period using data from the Korean Meteorological Administration. The mean square errors of
the 10 estimators were calculated to determine the optimal threshold using a semi-parametric bootstrap method. A modified
generalized Jackknife estimator determined the best performance in this study among the 10 estimators evaluated with regard
to estimating the mean square error of the shape estimator for the generalized Pareto distribution. 相似文献
168.
169.
Overview of geostationary ocean color imager (GOCI) and GOCI data processing system (GDPS) 总被引:4,自引:0,他引:4
Joo-Hyung Ryu Hee-Jeong Han Seongick Cho Young-Je Park Yu-Hwan Ahn 《Ocean Science Journal》2012,47(3):223-233
GOCI, the world??s first geostationary ocean color satellite, provides images with a spatial resolution of 500 m at hourly intervals up to 8 times a day, allowing observations of short-term changes in the Northeast Asian region. The GOCI Data Processing System (GDPS), a specialized data processing software for GOCI, was developed for real-time generation of various products. This paper describes GOCI characteristics and GDPS workflow/products, so as to enable the efficient utilization of GOCI. To provide quality images and data, atmospheric correction and data analysis algorithms must be improved through continuous Cal/Val. GOCI-II will be developed by 2018 to facilitate in-depth studies on geostationary ocean color satellites. 相似文献
170.
Hyu:n-Jeong Jeong Hyoungseok Leet Soon Gyu Hong Jang-Cheon Cho Hong Kum Lee Yoo Kyung lee 《极地研究(英文版)》2013,(4):223-230
Random mutagenesis is commonly used to study gene function. The screening of mutants exhibiting specific pheno- types assists in the identification of phenotype-related genes. In the current study, we isolated Antarctic bacteria, and developed a transposon Tn5 mutagenesis system. A total of 26 strains were isolated from seawater and freshwater near Antarctic King Sejong Research Station, King George Island. Six Psychrobacter strains were identified as psychrophilic, with optimal growth tempera- tures of 10~C or 15~C Psychrobacter cryohalolentis PAMC 21807 with a high growth rate at 4~C was selected for transposon mutagenesis. Tri-parental conjugation with a plasmid containing Tn5 produced 13 putative recombinants containing the selectable marker. Genomic Southern hybridization confirmed Tn5 existed as episomes for seven recombinants, and for a single recombinant, Tn5 was integrated into the genome of Psychrobacter cryohalolentis PAMC 21807. The result indicates that the mutagenesis method, although successful, has a relatively low rate. The psychrophilic bacteria isolated in this study may be a useful resource for studying cold adaptation mechanisms, and the mutagenesis method can be applied to genetic analysis. 相似文献