• Journal of Radiation Protection and Research
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• v.21 no.1
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• pp.27-39
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• 1996

The change in spent fuel characteristics by DUPIC fuel cycle(burnup of spent PWR fuel again in CANDU) is examined with time elapse since discharge. Major characteristics examined include isotopic concentration, radioactivity, decay heat radiotoxicity and radiation source-term of spent fuel material, which is existing in a type of spent PWR and DUPIC fuel. Behaviors of major nuclides contributing to such changes are also analyzed in terms of radionuclide concentration. From the analysis, the change in radionuclide concentration by DUPIC shows approximately 2% decrease in actinides concentration and 20% increase in fission products concentration. Radioactivity and decay heat of spent DUPIC fuel does not depend upon radionuclides concentrations, which is a unique in sence of general characteristics of spent fuel. In terms of gamma spectrum, spent DUPIC fuel shows lower values than that of spent PWR fuel by 40 to 50% in the range of $0.01{\sim}0.575$ MeV but much higher over 3.5MeV. Neutron Intensities of both spent fuels are mainly determined by $({\alpha},\;n)$ reaction and spontaneous fission reaction of actinides. Of them, especially, the spontaneous fission reaction Is a major neutron source-term, which causes that neutron intensities of spent DUPIC fuel $having{\sim}3.3$ times higher Cm-244 concentration are ${\sim}4$ times higher than that of spent PWR fuel.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.335-343
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• 2005

The Methodology of burnup calculation with EPMA test set up in this study. The spent fuel from PWR nuclear power plant was used as specimen. This $UO_2$ fuel with $3.2\%$ of enrichment had been irradiated up to 35,000 MWd/MTU(reference data). The burnup is very important factor for nuclear fuel to estimate all fuel behaviors in reactor. To measure amounts of fission products and actinides for the burnup calcualation, chemical analysis (destructive method) has been used but it mattes long experimental time and second radio-wastes. In this study, EPMA test was available to measure amount of fission products. Neodymium is able to be detected and quantified. It can be compared with the results from chemical analysis and ORIGEN-2 code calculation. Concentration of Nd from EPMA test showed good agreement with result of ORIGEN-2 code in the same burnup.

• Applied Microscopy
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• v.35 no.3
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• pp.113-119
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• 2005

The Methodology of burnup calculation with EPMA test set up in this study. The spent fuel from PWR nuclear power plant was used as specimen. This $UO_2$ fuel with 3.2% of enrichment had been irradiated up to 35,000 MWd/MTU. The burnup is very important factor for nuclear fuel to estimate all fuel behaviors in reactor. To measure amounts of fission products and actinides for the burnup calcualation, destructive method analysis has been used but it makes long experimental time and second radio-wastes. In this study, EPMA test was available to measure amount of fission products. Neodymium is able to be detected and quantified. It can be compared with the results from chemical analysis and ORIGEN-2 code calculation. Concentration of Nd from EPMA test showed good agreement with result of ORIGEN-2 code in the same burnup.

• Nuclear Engineering and Technology
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• v.27 no.1
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• pp.67-73
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• 1995

To investigate the storage behavior of the defective LWR spent fuel, air-oxidation tests on non-irradiated and irradiated U $O_2$ were performed. The weight gains of non-irradiated U $O_2$ specimens are characterized by the S-shape curves at 250-40$0^{\circ}C$ temperature range. One hundred percent conversion of U $O_2$ to U$_3$ $O_{8}$ corresponds with about 4％ weight increase. The activation energies are 110 kJ/mol above 35$0^{\circ}C$ and 153 kJ/mol below 35$0^{\circ}C$. The irradiated U $O_2$ specimens with about 35 GWD/MTU burnup were oxidized at 300-40$0^{\circ}C$ in air. They show a rapid increase of weight gain at the initial stage and a slow increase at the later stage when compared with non-irradiated U $O_2$. The activation energy under these conditions is 95 kJ/mol. Burnup and aging effects of irradiated U $O_2$ were also investigated at 35$0^{\circ}C$ in air environment, but the specimens appears insensitive to these variables.s.

• Geophysics and Geophysical Exploration
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• v.22 no.2
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• pp.62-71
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• 2019

We conducted DC resistivity and MT survey to obtain the resistivity structure of the central Myanmar basin. We tried to analyze the underground structure through the resistivity variation of Myanmar by performing representative geophysical survey methods because researches on the electrical resistivity structure are insufficient in Myanmar. The electrical resistivity is expected to be low considering the marine sedimentary rocks composed of shale and sandstone in this area. The DC resistivity and MT survey were carried out using SmartRho of Geolux Co., Ltd. and MTU-5A of Phoenix geophysics Ltd., respectively, to visualize the electrical resistivity structure of study area. DC resistivity and MT survey showed an electrical resistivity less than dozens of ohm-m within the depth of 100 m. In particular, MT survey data were almost similar to TM and TE modes in the frequency range above 1 Hz. The two-dimensional inversion of MT data showed a subsurface structure with low resistivity below 150 ohm-m divided into east-west direction. We confirmed that the inversions of DC resisitivity and MT data along an overlapped survey line represented similar results. In the future, considering the high electrical conductivity, it would be effective to perform DC resistivity and MT survey simultaneously to study the electrical resistivity structure of the central Myanmar basin.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11
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• pp.2900-2910
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• 1999

Since its introduction in the early 1990s, the quick growth of the world Wide Web (WWW) traffic raises the question whether past LAN packet traces still reflect the current situation or whether they have become obsolete. For this study, several LAN packet traces were obtained by monitoring the LAN of a typical academic environment. The tools for monitoring the network were a stand-alone HP LAN Protocol Analyzer as well as the free-ware software tool tcpdump. Our main focus was placed on acquiring a low-level overview of the LAN traffic. Thus, we could determine what protocols were mainly used and how the packet sizes were distributed. In particular, we were interested in establishing the amount of WWW traffic on the LAN, and what MIME-Types this traffic is subdivided into. Our results indicate that in a typical academic environment such as ours, conventional sources of LAN traffic such as NFS are still predominant, whereas WWW traffic plays a rather marginal role. Furthermore, we verified that a large portion of the network packets contains little or no data at all, while another significant portion of the packets has sizes around the MTU. Consequently, research in the networking field has to direct its focus on issues beyond the WWW.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.1-7
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• 2009

It is expected that a substantial amount of spent fuels will be transported from the four nuclear power plant (NPP) sites in Korea to a hypothetical centralized interim storage facility or a final repository in the near future. The cost for the transportation is proportional to the amount of spent fuels. In this paper, a cost estimation program is developed based on the conceptual design of a transportation system and a logistics analysis. Using the developed computer program, named as CASK, the minimum capacity of a centralized interim storage facility (CISF) and the transportation cost for PWR spent fuels are calculated. The PWR spent fuels are transported from 4 NPP sites to a final repository (FR) via the CISF. Since NPP sites and the CISF are located along the coast, a sea-transportation is considered and a road-transportation is considered between the CISF and the FR. The result shows that the minimum capacity of the interim storage facility is 15,000 MTU.

• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.366-372
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• 1996

The simulated spent PWR fuel pellet which is corresponding to the turnup of 33,000 MWD/MTU is prepared by adding 11 fission-product elements to UO$_2$. The simulated spent fuel pellet is treated at 40$0^{\circ}C$ in air (oxidation), at 110$0^{\circ}C$ in air (high-temperature treatment), and at $600^{\circ}C$ in hydrogen (reduction). The product is treated through additional addition and reduction up to 3 cycles. Pellets are completely pulverized by the first oxidation, and the high-temperature treatment causes particle and crystallite to grow and surface to be smooth, and thus particle size significantly increases and surface area decreases. The reduction following the high-temperature treatment decreases much the particle size by means of the formation of intercrystalline cracks. The particle size decreases a little during the second oxidation and reduction cycle and then remains nearly constant during the third and fourth cycles. Surface area of pounder increases progressively with the repetition of oxidation and reduction cycles, mainly due to the formation of Surface cracks. The degradation of surface area resulting from high-temperature treatment is restored by too subsequent resulting oxidation and reduction cycles.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1501-1504
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• 2001

MPEG-4 비디오 스트림을 전송하기 위해 RTP 프로토콜을 사용할 경우 RTP 패킷에 MPEG-4 비디오 스트림을 수용하기에 적절한 페이로드 포맷이 정의되어야 한다. RTP 페이로드에 MPEG-4 비디오 스트림을 수용하기 위한 기존의 방법은 MPEG-4 코덱으로부터 생성된 비디오 스트림의 형태에 따라 많은 종류의 페이로드 포맷이 정의되어야 하는 문제점이 있거나, 혹은 각 계층에서 생성된 스트림을 (in 패킷화하는 방법이 명료하지 않은 문제점 등이 있다. 이 논문에서는 MPEG-4 시스템을 사용 하지 않고, MPEG-4 비디오 기초스트림을 RTP 패킷에 담아 전송하기 위한 새로운 RTP 페이로드 포맷을 제안하였고, 제안된 포맷을 이용하여 MPEG-4 비디오를 전송하는 시스템을 설계 및 구현하였다. 제안된 RTP 페이로드 포맷은 비디오 객체(Video Object)에 대한 RTP 페이로드 포맷만을 정의하여 포맷의 종류를 최소화함으로써 포맷의 종류가 많아짐으로해서 생기는 부가적인 오버헤드를 감소시켰으며, 또한 하나의 RTP 패킷에는 단 하나의 비디오 객체에 대한 정보만을 저장하여 비디오 객체간의 독립성을 유지하였다. 제안된 포맷을 이용하여 구현된 MPEG가 비디오 전송시스템은 RTP 패킷의 크기를 pad-MTU와 같거나 작게 설계함으로써, IP 계층에서 RTP패킷의 단편화 현상이 발생하지 않고 효율적인 전송이 이루어지도록 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.532-534
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• 2000

IPv4(Internet Protocol version 4)의 차세대 버전인 IPv6는 기존 IPv4의 문제점인 주소부족 및 새로운 부가기능 등의 필요성 때문에 IETF(Internet Engineering Task Force)에서 IPv4를 대체하기 위해 개발한 프로토콜이다. 하지만 IPv4를 어느 한순간에 IPv6로 대체하는 것은 불가능하기 때문에 기존 IPv4와의 호환 및 연동을 위한 터널링 및 기타 여러 가지 transition mechanism들이 고려되고 있다. 이러한 mechanism들 중에서 최근 표준으로 발표된 NAT-PT(Network Address Translation $\square$ Protocol Translation)는 DNS-ALG (Domain Name System $\square$ Application Level Gateway)라는 개념을 도입하여 IPv4와 IPv6간의 양방향 주소변환 및 프로토콜 변환기능을 수행한다. 각각의 기능에서 주소 변환은 주소크기와 형식이 다른 IPv4와 Pv6간의 서로 상대 노드를 엑세스할 수 있도록 하고 프로토콜 변환은 다른 버전의 프로토콜을 사용하는 노드들이 상대노드가 보낸 패킷의 헤더정보를 이해할 수 있도록 한다. 그리고 이러한 기본적인 변환 외에 헤더정보의 정확한 전달을 위해서는 기존의 path MTU(Maximum Transgfer Unit) discovery 그리고 pseudo header checksum 등도 고려되어야 한다.