• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.3
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• pp.40-49
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• 1989

A variable-state block interference channel model is presented which matches asynchronous multiple-access slow frequency-hopped spread-spectrum systems which suffer from bursts of interference of variable duration. For variable-state block interference channels test pattern techniques combined with interleaving are presented from which the decoder obtain side information about channel states. By examining test patterns the decoder estimates which parts of data blocks are affected by interference and regards the parts of blocks affected by interference as erasures. Since the presence of test patterns reduces the number of bits for data transmission, test patterns are not useful for variable-state block interference channels for small hit probability, It is shown that test patterns increase the capacities of variable-state block interference channels for large hit probability. It is also shown that test patterns provide a almost full side information about channel states for certain values of parameters.

• Journal of Environmental Policy
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• v.10 no.1
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• pp.3-25
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• 2011

Recently, a number of local governments as well as private organizations have spearheaded the release of animals into the natural ecosystem in Korea. In 2002, most of these animals released were mammals and birds, but the parameter was gradually expanded to include fish, amphibians, and invertebrates in addition to mammals and birds in 2007, with an increased overall number of animals released. Such increase has not only posed ecological, economic, and public health risks, but also yielded an increase in damages incurred by releasing animals historically or ecologically alien to a given region without thorough risk assessment. The most significant cause of such risks was a critical lack of risk management and regulatory schemes addressing the release of animals into the natural ecosystem. In stark contrast, developed countries long before established the requisite risk management and regulatory schemes either by complying with the IUCN/SSC's Guidelines for Re-Introductions or devising them independently. In this context, the current study has examined the release of animals into the natural ecosystem in Korea and, based on the investigation, asserted a strong need for proper risk management. Moreover, the study has presented systematic risk management and regulatory schemes suitable for the Korean milieu based on a comparative analysis of those employed in developed countries.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.22-29
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• 2012

Robot related injuries in industrial accidents statistics during 2008~2010 have accounted for a total of 109 cases equivalent to 30~40 cases for each of those years. The number of injured compared to the dissemination of industrial robots(51,302 units/2004) can be regarded as quite low. However, the fatal injuries sustained by 7 (6.4%) out of 109 cases paints the stark reality of robot-related accident fatalities. It is a sad probability that as the automation process expands its use of industrial robots which have increased significantly in demand, the incidence of workplace accidents will also increase. Therefore, the incidence of accidents throughout the period of 2008~2010 has been analysed to prevent the injuries due to the increased use of industrial robots. In the analysis, the injuries occurred during the industrial robot operation accounted for 45.9% of the entire accidents. Thus, we examined the present status of the industrial robot operation to analyze the root cause of accidents occurred in our studied time period. We looked at a total of 469 workplaces. 456 workplaces responded in the year 2009 and survey studies were implemented at 13 of the 29 workplaces where work injuries were sustained in the year 2010. Even where protective measures and interlock devices were in place, our studies indicated that workers could access the robot area to perform the tasks in 188 sites(40.1%). Also, the 143 sites(30.5%) had control measures and equipment located in the safety fence. In addition, the robots found at 164 sites(35.0%) could be restarted without additional restarting operation. These three causes accounted for most of the workplace injuries during the industrial robot operations. Futhermore, we confirmed the fact that the protective measures of the current safety regulations were not strictly enforced. Based upon our studies and the investigation of the present status of the industrial robot operation, higher standards in training and supervision of workers in the robot operation must quickly be met in order to prevent these industrial injuries.