Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.

The intention of this paper is to respond to the increase in electric power demand and global environmental issues in iron and steel plants. In particular, the authors studied the characteristics of the power flow from a distributed generation (DG) system connected to the electrical power system of a steel plant. In addition, the authors carried out an economic analysis of the DG system by calculating the capital investment cost that could convert the profit of the DG into a certain profit. The research was conducted based on the power system configuration and basic data of a steel plant in operation in Korea. To analyze the unconnected DG of the power system, a transmission voltage target was set, and the voltage characteristics of 22.9 and 6.6 kV systems were analyzed. The authors analyzed the connected DG system in terms of the effect of link location, power factor, and output power by case. The authors also studied the power loss variation in the output power of a DG system. Various simulations with MATLAB software and NPV (Net Present Value) and IRR (Internal Rate of Return) methods were run in an economic analysis to compare the case of not introducing an energy storage system (ESS), and the case of introducing an ESS in terms of comprehensive energy utilization. The results of the economic analysis indicated that the scenario with ESS is more economically advantageous, resulting from the peak power reduction effect and the evasion cost due to the elimination of the power generation operation of the peak load. Developed countries have established best available technology (BAT) standards and developed related practices to apply them to industrial plants, actively preparing for environmental issues in the future. In Korea and in some other countries, the application of distributed generation in conjunction with the steel plant sector will be effective for improving energy efficiency and responding to environmental issues.

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