Time filter

Source Type

Shin W.,Korea Basic Science Institute | Shin W.,Yonsei University | Oh J.,Korea Agency for Infrastructure Technology Advancement KAIA | Choung S.,Korea Basic Science Institute | And 5 more authors.
Chemosphere | Year: 2016

Chronic exposure even to extremely low specific radioactivity of natural uranium in groundwater results in kidney problems and potential toxicity in bones. This study was conducted to assess the potential health risk via intake of the groundwater containing uranium, based on the determination of the uranium occurrence in groundwater. The groundwater was investigated from a total of 4140 wells in Korea. Most of the groundwater samples showed neutral pH and (sub-)oxic condition that was influenced by the mixing with shallow groundwater due to long-screened (open) wells. High uranium contents exceeding the WHO guideline level of 30 μg L−1 were observed in the 160 wells located mainly in the plutonic bedrock regions. The statistical analysis suggested that the uranium component was present in groundwater by desorption and re-dissolution processes. Predominant uranium phases were estimated to uranyl carbonates under the Korean groundwater circumstances. These mobile forms of uranium and oxic condition facilitate the increase of potential health risk downgradient. In particular, long-term intake of groundwater containing >200 μg U L−1 may induce internal exposure to radiation as well as the effects of chemical toxicity. These high uranium concentrations were found in twenty four sampling wells of rural areas in this study, and they were mainly used for drinking. Therefore, the high-level uranium wells and neighboring areas must be properly managed and monitored to reduce the exposure risk for the residents by drinking groundwater. © 2016 Elsevier Ltd

Chung Y.,Korea Agency for Infrastructure Technology Advancement KAIA | Shin A.H.-C.,Southern University and A&M College
International Journal of Pavement Research and Technology | Year: 2015

Due to the daily and seasonal fluctuation of temperature gradients, accurate temperature gradients under local climatic conditions are imperative to correctly predict the performance of PCC pavements. In this study, temperature sensors were installed at various depths (0-, 6.4-,12.8-, 19.2-,and 25.6-cm) in a PCC pavement section to monitor temperature gradients. Based on the measured daily and seasonal temperature data, correlations between air temperature and surface temperature, as well as surface temperature and slab temperature difference, were developed. A finite element analysis was performed to simulate the temperature variation in a PCC pavement, and the analysis results were compared to the field measurement. A local calibration of the enhanced integrated climatic model(EICM)was conducted by comparing the field-measurements with the EICM-predicted temperature gradients. The conclusion demonstrated that surface temperature, rather than air temperature, would better predict temperature gradient in PCC pavements for the input data in EICM. © Chinese Society of Pavement Engineering.

Loading Korea Agency for Infrastructure Technology Advancement KAIA collaborators
Loading Korea Agency for Infrastructure Technology Advancement KAIA collaborators