This work presents irradiation test results of a commercial digital-to-analog converter (DAC) which is an essential component widely used in circuits and systems to convert natural signals from digital bits. Especially, a DAC requires a radiation tolerance in nuclear applications, for instance a nuclear black box which can store and transfer necessary data observed the status of nuclear reactors in accident situations like Fukushima. The selected DAC is AD5433 of 10-bit and 10 MHz for multipurpose applications such as waveform generators, analog processing, instruments, programmable amplifiers and attenuators, digitally controlled calibration, composite video, and ultrasound. The test PCB includes two design-under-test (DUT) DACs controlled by a microcontroller communicating with a PC. We observed the DUTs for 21 hours in the facility of high gamma energy irradiation at KAERI. The 10V DAC outputs reached 3% of an allowable error after 51 and 48 mins at the irradiation dose of 846 and 825 Gy, respectively. In the environment of severe accidents, electrical components for observing reactor behaviors should be survived up to 5 kGy in total ionizing dose for approximately 72 hours that is minimum time to mitigate the accidental situation as soon as possible. However, the DACs were operated under 1 kGy, that is, we need a better DAC specialized for the nuclear applications required such harsh environments.

Field experiments were carried out to analyze the relation between the particulate matter and the vehicle traffic in the surrounding roads near a Institute of Health and Environment (IHE) located at Yuseong-gu, Daejeon. Also, major facts to generate the particulate matter were analyzed using the past measured data. As a result of the analysis, the contribution of the particulate matter from the vehicles in a road showed to take a large portion in 2015 and 2016. As a result of connection with traffic data in Daejeon, the concentrations of particulate matter increased during rush hour and they showed the similar patterns near a IHE. The generation rates of the particulate matter from the vehicles presented a large portion in summer and winter that inflow from the surrounding cities have been relatively small, and it always occurred for the conditions without rainfall. It is anticipated that the concentration of PM₁₀ generated by the road traffic would be reduced in the range of 10㎍·m^-3~14㎍·m^-3 through the control and detour of vehicles.