• Journal of Radiation Protection and Research
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• v.31 no.1
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• pp.9-15
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• 2006

A long-range atmospheric dispersion model named LADAS has been developed to understand the characteristics of the transport and diffusion of radioactive materials released into atmosphere. The developed numerical model for validation was compared with the results of the ETEX which is the long-range field tracer experiment. As a comparative study, the calculated concentration distributions agreed well in the case of the usage of the mixing heights calculated by the Richardson number than the usage of the constant mixing heights in LADAS model. Also, the calculated concentrations agreed with the time series of the measured ones at some sampling points.

• Journal of Radiation Protection and Research
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• v.27 no.3
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• pp.171-179
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• 2002

The three-dimensional long-range dispersion model has been developed to understand the characteristics of the transport and diffusion of radioactive materials released into atmosphere. The model is designed to compute air concentration and ground deposition at distances up to some thousands of kilometers from the source point in horizontal direction. The vertical turbulent motion is considered separately within the mixing layer and above the mixing layer. The test simulation was performed In the area of Northeast Asia. The release point was assumed in the east part of China. The calculated concentration distributions art mainly advected toward the southeast part of release point by the wind fields. The developed model will be used to estimate the radiological consequences against a nuclear accident. The model will be supplemented by the comparative study using the data of the long-range field experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.82-87
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• 2000

인터넷을 계기로 발전한 H'통신은 원래 국경의 울타리가 없이, 음성/데이터/비디오의 종합전송이 가능하며 n대n의 모든 커뮤니케이션에 적함하고 또한 매우 가격이 싸기 때문에 시내/장거리/국제통신의 구별도 점차 소멸해가는 추세이다. 이에 따라 과거 독점시대의 전화중심 사업을 전개해온 각 국의 주요 통신사업자들은 기술, 서비스, 응합 등의 급격한 변화와 글로벌한 경쟁시대를 맞이하여 명확한 경영비젼과 그것에 입각한 비즈니스모델을 확립하고 신속히 대응하지 않으면 안될 상황에 처해 있다. 따라서 각 국의 주요 통신사업자들은 인터넷 시대에 뒤떨어지지 않기 위해서 멀티미디어 광대역 백본망을 건설에 몰두하고 있으며, ADSL, 케이블모뎀 등을 통한 초고속광대역접속서비스 제공에 주력하고 있다. 또한 영국을 중심으로 무료 인터넷접속서비스가 확산되고 있어 이 분야의 경쟁은 더욱 치열해지고 있다. 본고에서는 이러한 변화하는 환경에 대처하고 긴는 주요 구미의 통신사업자의 인터넷사업 대응 전략에 관해 살펴보고자 한다.

• Journal of Radiation Protection and Research
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• v.39 no.3
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• pp.127-133
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• 2014

North Korea's uranium enrichment facility is a matter of international concern. It is of particular alarming to South Korea with regard to the security and safety of the country. This situation requires continuous monitoring of the DPRK and emergency preparedness on the part of the ROK. To assess the detectability of an undeclared uranium enrichment plant in North Korea, uranium concentrations in the air at both a short and a long distance from the enrichment facility were estimated. $UF_6$ source terms were determined by using existing information on North Korean facility and data from the operation experience of enrichment plants from other countries. Using the calculated source terms, two atmospheric dispersion models (Gaussian Plume Model and HYSPLIT models) and meteorological data were used to estimate the uranium particle concentrations from the Yongbyon enrichment facility. A maximum uranium concentration and its location are dependent upon the meteorological conditions and the height of the UF6 release point. This study showed that the maximum uranium concentration around the enrichment facility was about $1.0{\times}10^{-7}g{\cdot}m^{-3}$. The location of the maximum concentration was within about 0.4 km of the facility. It has been assumed that the uranium sample of about a few micrograms (${\mu}g$) could be obtained; and that few micrograms of uranium can be easily measured with current measurement instruments. On the contrary, a uranium concentration at a distance of more than 100 kilometers from the enrichment facility was estimated to be about $1.0{\times}10^{-13}{\sim}1.0{\times}10^{-15}g{\cdot}m^{-3}$, which is less than back-ground level. Therefore, based on the results of our paper, an air sample taken within the vicinity of the Yongbyon enrichment facility could be used to determine as to whether or not North Korea is carrying out an undeclared nuclear program. However, the air samples taken at a longer distance of a few hundred kilometers would prove difficult in detecting a clandestine nuclear activities.