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Piezoelectric devices such as piezoelectric speaker, motor, and actuator have been actively researched. Accordingly, for developing the ceramics capable of being sintered at low temperature for piezoelectric devices, 0.97(Na0.52K0.443Li0.037)(Nb0.923Sb0.04 Ta0.037)O3 − 0.03(Bi0.5Na0.5)0.9(Sr)0.1ZrO3 ceramics were manufactured according to x (=sintering time) and their piezoelectric and dielectric properties were systematically investigated. At the x = 9 h, the best piezoelectric properties of d33 = 244.33pC/N εr = 1475, and kp = 0.441 were appeared, respectively, for piezoelectric devices. [ABSTRACT FROM AUTHOR]

A novel on-board hydrogen generation concept using Al coil with NaOH was investigated. The reaction rate was successfully controlled by introducing a pumping system for the NaOH solution. The time for the flow to develop fully was mainly dependent on the solution temperature, and the fastest start time recorded was 60 sec at a solution temperature of 70°C. The maximum H2generation rate was 200 L min–1with a prototype design of the on-board hydrogen generation system 1/8 times the size of a full-size reactor. The H2generation process coupled with the solution pumping system was simulated with three-dimensional fluid dynamic software, and the calculated H2flow and temperature rise of the system were validated with experimental data. [ABSTRACT FROM AUTHOR]

Dietary intake is the most important source of exposure to dioxins for the general population. This pathway contributes more than 90% of the daily intake for the general population of Korea. The objective of this study was to assess current exposure to dioxin-like compounds in fish and shellfish consumed by the general population in Korea. Residues of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and dioxin-like, non-, and mono-substituted polychlorinated biphenyls (co-planar PCBs) were quantified in 32 fish and shellfish collected from domestic fisheries markets. The contributions of individual DL-PCB congeners to the total 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQ) were greater than 50%. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents based on the TCDD equivalency factors (TEFs) developed by the World Health Organization (TEQWHO) were compared to guidelines suggested for the protection of human health by the World Health Organization (WHO). The greatest TEQ concentration was observed in herring, followed by that in dried anchovy and Sailfin sandfish. The exposure to dioxin-like compounds from current fish consumption patterns was estimated to be 72 pg TEQWHO/day, which is equal to 1. 2 pg TEQWHO/kg, bw/d, a value that is less than the current tolerable daily intake (TDI) guideline in Korea, which is 4 pg TEQWHO/kg, bw/d. The relatively great exposure was determined to be due to greater fish consumption rate in Korea, rather than greater concentrations of residues in food. [ABSTRACT FROM AUTHOR]

Sixty seven sediment samples were collected from Kyeonggi Bay, Korea, including the mouth of Han River, Incheon Harbor, the Namdong industrial complex, and the open sea. Collections were conducted in December, 1995 and samples were maintained frozen-20 C until analysis. Dichloromethane extracts were analysed for their content of CYP1A1 inducing compounds with a P450RGS reporter gene system assay, and for polycyclic aromatic hydrocarbons PAHs . Sediment samples were also analysed for organic carbon OC content and grain size, to aid in evaluating the relationship between contamination and physical nature of the sediments. The responses of the P450RGS assay to the sediment extracts were expressed as u g of benzo a pyrene toxic equivalents per g dry weight u g g-1 BaPTEQ , and these values correlated well r 2 0.624 with total PAHs. BaPTEQ values were also highly correlated with the OC content of the sediments. The determination of P450RGS BaPTEQ is a useful tool, because it is both a rapid and inexpensive means of assessing the potential toxicity of organic compounds in environmental sediment samples. These values represent an estimate of the levels of compounds in the sediment that are potentially available to organisms through chronic exposure to pore water or ingestion of benthic species. We believe BaPTEQ values are more useful than tables of specific PAH concentrations, if the purpose of the investigation is to either obtain a rapid screening of an area or to develop some form of ecological or human health risk assessment. [ABSTRACT FROM AUTHOR]