• Nuclear Engineering and Technology
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• v.41 no.9
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• pp.1143-1156
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• 2009

The SPACE code that is based on a multi-dimensional two-fluid, three-field model is under development for licensing purposes of pressurized water reactors in Korea. Among the participating research and industrial organizations, KAERI is in charge of developing the physical models and correlation packages for the constitutive equations. This paper introduces a developed wall-to-fluid heat transfer package for the SPACE code. The wall-to-fluid heat transfer package consists of twelve heat transfer subregions. For each sub-region, the models in the existing safety analysis codes and the leading models in literature have been peer reviewed in order to determine the best models which can easily be applicable to the SPACE code. Hence a wall-to-fluid heat transfer region selection map has been developed according to the non-condensable gas quality, void fraction, degree of subcooling, and wall temperature. Furthermore, a partitioning methodology which can take into account the split heat flux to the continuous liquid, entrained droplet, and vapor fields is proposed to comply fully with the three-field formulation of the SPACE code. The developed wall-to-fluid heat transfer package has been pre-tested by varying the independent parameters within the application range of the selected correlations. The smoothness between two adjacent heat transfer regimes has also been investigated. More detailed verification work on the developed wall-to-fluid heat transfer package will be carried out when the coupling of a hydraulic solver with the constitutive equations is brought to completion.

• Journal of Radiation Protection and Research
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• v.46 no.3
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• pp.134-142
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• 2021

Background: From 2018 to 2020, the Expert Study on Public Understanding after the Fukushima Daiichi Nuclear Power Plant Accident (the Expert Study Group) identified and analyzed activities designed to promote public understanding of science and radiation since the Fukushima accident, and held discussions on how to achieve public understanding in the situation where public confidence has been lost, and how experts should prepare for dealing with the public. This panel session was held at the 53^rd meeting of the Japan Health Physics Society on June 30, 2020. Materials and Methods: First, three subgroup (SG) leaders reported their research methods and results. Then, two designated speakers, who participated as observers of the Expert Study Group, commented on the activities. Next, the five speakers held a panel discussion. Finally, the rapporteur summarized. Results and Discussion: SG leaders presented reports from researchers and practitioners in health physics and environmental risks who provided information after the Fukushima accident. During the discussion, experts in sociology and ethics discussed the issues, focusing on the overall goals of the three groups, local (personal) and mass communication, and ethical values. Many of the activities instituted by the experts after the accident were aimed at public understanding of science (that is, to provide knowledge to residents), but by taking into account interactions with residents and their ethical norms, the experts shifted to supporting the residents' decision-making through public engagement. The need to consider both content and channels is well known in the field of health communication, and overlaps with the above discussion. Conclusion: How to implement and promote the public engagement in society was discussed in both the floor and designated discussions. Cooperation between local communities and organizations that have already gained trust is also necessary in order to develop relationships with local residents in normal times, to establish an information transmission system, and to make it work effectively.

• Journal of Radiation Protection and Research
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• v.48 no.2
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• pp.84-89
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• 2023

Background: Food consumption is one of the most important routes for radionuclide intake for the public; therefore, there is the need to have a comprehensive understanding of the amount of radioactivity in food products. Consumption of radionuclide-contaminated food could increase potential health risks associated with exposure to radiation such as cancers. The present study aims to determine radioactivity levels in some food products (milk, rice, sugar, and wheat flour) consumed in Mali and to evaluate the radiological effect on the public health from these radionuclides. Materials and Methods: The health impact due to ingestion of radionuclides from these foods was evaluated by the determination of activity concentration of radionuclides ²³⁸U, ²³²Th, ⁴⁰K, and ¹³⁷Cs using gamma spectrometry system with high-purity germanium detector and radiological hazards index in 16 samples collected in some markets, mall, and shops of Bamako-Mali. Results and Discussion: The average activity concentrations were 9.8±0.6 Bq/kg for ²³⁸U, 8.7±0.5 Bq/kg for ²³²Th, 162.9±7.9 Bq/kg for ⁴⁰K, and 0.0035±0.0005 Bq/kg for ¹³⁷Cs. The mean values of radiological hazard parameters such as annual committed effective dose, internal hazard index, and risk assessment from this work were within the dose criteria limits given by international organizations (International Commission on Radiological Protection and United Nations Scientific Committee on the Effects of Atomic Radiation) and national standards. Conclusion: The results show low public exposure to radioactivity and associated radiological impact on public health. Nevertheless, this study stipulates vital data for future research and regulatory authorities in Mali.

• Korean Security Journal
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• no.29
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• pp.193-222
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• 2011

Our country successfully hosted the G20 summit in Seoul in November, 2010. Afterwards, however, the Yeonpyungdo shelling incident took place by the North, and the North Korean nuclear issue have strained interKorean relations. Our country is going to host the nuclear security summit, which is of great significance at this point of time. The nuclear security summit is to be attended by 47 countries. The participant countries of this summit is larger in number than those of the ASEM, APEC and the G20 summit that our country has ever hosted. That is a large-scale international conference that invites the UN, the IAEA and the EU, which are three major nuclear-related international organizations. A successful hosting of the nuclear security summit will serve as an opportunity to boost our country's national prestige, and is likely be beneficial to the settlement of the North Korean nuclear issue. Like other international submits in foreign countries, however, violent anti-globalization demonstrations are expected to occur when the nuclear security summit is held in April next year. The purpose of this study was to make a case analysis of demonstrations during multilateral international conferences hosted by foreign countries over ten years between 1999 and 2009, to examine the controversial points over the demonstrations, and ultimately to seek ways of ensuring safety against possible assemblies and demonstrations during the forthcoming nuclear security summit, which is scheduled to be held in April next year. The findings of the study on feasible security measures are as follows: First, information and intelligence gathering should be reinforced, and the inspection should be stepped up. Second, pacification among domestic NGOs and the supplementation of the existing legal devices are required. Third, publicity should be strengthened. Fourth, riot police officers should be selected as early as possible to bolster their education and training, and more reinforced emergency measures should be taken. It's needed to seek assistance from the military as one of emergency measures, and national defense readiness should be bolstered across the nation in collaboration with the Ministry of National Defense when the summit is near at hand. Finally, CBR countermeasures should be taken in preparation for CBR terrorism.

• The Korean Journal of Nuclear Medicine Technology
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• v.25 no.2
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• pp.29-34
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• 2021

Purpose Sample reception environment system in nuclear medicine has not changed much compared to 20 years ago. When preparing sample for in vitro test, there was no significant change because the test was carried out by generating an own specimen from the parent specimen. In this study, We would like to introduce a method that automatically removes the sample cap using the automated decapper equipment and enables automatic reception at the same time. In addition, including a provisional reception system. Materials and Methods In 2019, it was intended to get a device that automatically removes the cap of a patient's blood sample. This equipment is the same as the equipment used in the Department of Laboratory Medicine (Vacuette Ⓡ Unicap Belt Decapper, Greiner bio-one, Austria). However, the purchase was delayed due to differences in tube size, budget, and space. In January 2020, we borrowed domestic automatic decapper equipment and modified it to suit our laboratory environment. After 9 months, we were able to introduce a system that automatically removes the lid of a patient's blood sample and at the same time automatically accepts the test. And, through the provisional reception system, it was possible to know the arrival of the specimen in a short time. Results With the use of an automatic decapper device, the sample cap was automatically removed, and the reception proceeded at the same time. So, it was very efficient at work because it shortened the sample preparation time by about 20 minutes. In addition, it was possible to prevent the examiner's musculoskeletal disorders caused by repeated wrist use. After using the provisional reception system, patients were able to be discharged quickly, and the number of phone calls to confirm the arrival of samples was reduced. Conclusion Most hospitals have about four employees in the nuclear medicine in vitro laboratory. It is effective to use automatic decapper equipment and a provisional reception system for organizations that perform work with the minimum number of personnel.

• Convergence Security Journal
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• v.12 no.1
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• pp.97-107
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• 2012

Our nation, of which the term of dispatching troops is winded up at the end of this year, is facing presidential election time including the nuclear security summit meeting in March, opening of EXPO in May, and the general election. Hence, the possibility to select our nation at the strategy forming public opinion of military withdrawal through Taliban's terror is high. It coincides with public affair strategy of Taliban terror and learning effect by the past cases. If the possibility of terror threat of Taliban along with this is summarized, the period of threat will concentrate on and be heightened in the first half when the nuclear security summit meeting and EXPO open in our nation, and target and method have high possibility of collision terror of bomb carrying vehicle and suicide bomb on national government organizations or American facilities, and etc, and possibility of kidnapping on our people such as oversea tourists, missionaries, and so on. Terror groups joining the criminal act is to use Islam illegal aliens who already acquire base in our nation or entry maneuver of specialized terrorists connected to Al-Qaeda. Pretext of such terror is withdrawal of our military and western allies stationed in Afghanistan. Therefore, publicity terror of Taliban against our people living overseas and security measure of international events such as the world nuclear security summit meeting, Yeosu EXPO, and etc in the first half of this year should be thoroughly prepared, domestic illegal aliens' movement should be comprehended, and measure blocking international terrorists' relating to Taliban infiltration into our nation should be sought for. Also, there is need of early announcement of government's political will on our military stationed in Afghanistan.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3874-3897
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• 2023

A high-fidelity computational fluid dynamics (CFD) analysis was performed using the Large Eddy Simulation (LES) model for the lower plenum of the High-Temperature Test Facility (HTTF), a ¼ scale test facility of the modular high temperature gas-cooled reactor (MHTGR) managed by Oregon State University. In most next-generation nuclear reactors, thermal stress due to thermal striping is one of the risks to be curiously considered. This is also true for HTGRs, especially since the exhaust helium gas temperature is high. In order to evaluate these risks and performance, organizations in the United States led by the OECD NEA are conducting a thermal hydraulic code benchmark for HTGR, and the test facility used for this benchmark is HTTF. HTTF can perform experiments in both normal and accident situations and provide high-quality experimental data. However, it is difficult to provide sufficient data for benchmarking through experiments, and there is a problem with the reliability of CFD analysis results based on Reynolds-averaged Navier-Stokes to analyze thermal hydraulic behavior without verification. To solve this problem, high-fidelity 3-D CFD analysis was performed using the LES model for HTTF. It was also verified that the LES model can properly simulate this jet mixing phenomenon via a unit cell test that provides experimental information. As a result of CFD analysis, the lower the dependency of the sub-grid scale model, the closer to the actual analysis result. In the case of unit cell test CFD analysis and HTTF CFD analysis, the volume-averaged sub-grid scale model dependency was calculated to be 13.0% and 9.16%, respectively. As a result of HTTF analysis, quantitative data of the fluid inside the HTTF lower plenum was provided in this paper. As a result of qualitative analysis, the temperature was highest at the center of the lower plenum, while the temperature fluctuation was highest near the edge of the lower plenum wall. The power spectral density of temperature was analyzed via fast Fourier transform (FFT) for specific points on the center and side of the lower plenum. FFT results did not reveal specific frequency-dominant temperature fluctuations in the center part. It was confirmed that the temperature power spectral density (PSD) at the top increased from the center to the wake. The vortex was visualized using the well-known scalar Q-criterion, and as a result, the closer to the outlet duct, the greater the influence of the mainstream, so that the inflow jet vortex was dissipated and mixed at the top of the lower plenum. Additionally, FFT analysis was performed on the support structure near the corner of the lower plenum with large temperature fluctuations, and as a result, it was confirmed that the temperature fluctuation of the flow did not have a significant effect near the corner wall. In addition, the vortices generated from the lower plenum to the outlet duct were identified in this paper. It is considered that the quantitative and qualitative results presented in this paper will serve as reference data for the benchmark.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.133-140
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• 2016

Backgrounds: The accident at Fukushima Daiichi Nuclear Power Plant (NPP), March 2011, caused serious radioactive contamination over wide area in east Japan. Therefore, it is important to know the effect of the accident and the status of NPP. Materials and Methods: This paper provides a review on the status of radiation dose and radioactive contamination caused by the accident on the basis of publicized information. Results and Discussion: Monitoring of radiation dose and exposure dose of residents has been conducted extensively by the governments and various organizations. The effective dose of general residents due to the accident proved to be less than a mSv both for external and internal dose. The equivalent committed dose of thyroid was evaluated to be a few mSv in mean value and less than 50 mSv even for children. Monitoring of radioactivity concentration has been carried out on food ingredients, milk and tap water, and actual meal. These studies indicated the percentage of foods above the regulation standard was over 10% in 2011 but decreasing steadily with time. The internal dose due to foods proved to be tens of ${\mu}Sv$ and much less than that due to natural $^{40}K$ even in the Fukushima area and decreasing steadily, although high level concentration is still observed in wild plants, wild mushrooms, animals and some kind of fishes. Conclusion: According to extensive studies, not only the effect of the accident but also the pathway and countermeasures against radioactive contamination have been revealed, and they are applied very effectively for restoration of environment and reconstruction of the area.

• Korean Journal of Computational Design and Engineering
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• v.18 no.3
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• pp.200-210
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• 2013

It has become important to manage plant data effectively and to share these data among different organizations that are located in different places and participate in a variety of lifecycle phases. ISO 15926 is an international standard for integration of lifecycle data for process plants including oil and gas facilities. This standard consists of several parts providing a generic data model, reference data, and implementation methods. iRINGTools is a tool developed for the exchange of plant design data. This tool supports the implementation methods specified in ISO 15926. In this paper, the exchange of plant design data using iRINGTools is investigated. For this, sample P&ID data was modeled and data exchange experiment was performed. From the experiment, a data exchange procedure based on ISO 15926 is established and design data types that can be practically exchanged using ISO 15926 were identified.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.491-494
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• 2019

The results from the analysis of recent security breach cases of industrial control systems revealed that most of them were caused by the employees of a partner company who had been managing the control system. For this reason, the majority of the current company security management systems have been developed focusing on their performances. Despite such effort, many hacking attempts against a major company, public institution or financial institution are still attempted by the partner company or outsourced employees. Thus, the institutions or organizations that manage Industrial Control Systems (ICSs) associated with major national infrastructures involving traffic, water resources, energy, etc. are putting emphasis on their security management as the role of those partners is increasingly becoming important as outsourcing security task has become a common practice. However, in reality, it is also a fact that this is the point where security is most vulnerable and various security management plans have been continuously studied and proposed. A system that enhances the security level of a partner company with a Virtual Desktop Infrastructure (VDI) has been developed in this study through research on the past performances of partner companies stationed at various types of industrial control infrastructures and its performance outcomes were statistically compiled to propose an appropriate model for the current ICSs by comparing vulnerabilities, measures taken and their results before and after adopting the VDI.