• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1825-1834
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• 2022

Performing high-fidelity computational fluid dynamics (HF-CFD) to predict the flow and heat transfer state of the coolant in the reactor core is expensive, especially in scenarios that require extensive parameter search, such as uncertainty analysis and design optimization. This work investigated the performance of utilizing a multi-fidelity reduced-order model (MF-ROM) in PWR rod bundles simulation. Firstly, basis vectors and basis vector coefficients of high-fidelity and low-fidelity CFD results are extracted separately by the proper orthogonal decomposition (POD) approach. Secondly, a surrogate model is trained to map the relationship between the extracted coefficients from different fidelity results. In the prediction stage, the coefficients of the low-fidelity data under the new operating conditions are extracted by using the obtained POD basis vectors. Then, the trained surrogate model uses the low-fidelity coefficients to regress the high-fidelity coefficients. The predicted high-fidelity data is reconstructed from the product of extracted basis vectors and the regression coefficients. The effectiveness of the MF-ROM is evaluated on a flow and heat transfer problem in PWR fuel rod bundles. Two data-driven algorithms, the Kriging and artificial neural network (ANN), are trained as surrogate models for the MF-ROM to reconstruct the complex flow and heat transfer field downstream of the mixing vanes. The results show good agreements between the data reconstructed with the trained MF-ROM and the high-fidelity CFD simulation result, while the former only requires to taken the computational burden of low-fidelity simulation. The results also show that the performance of the ANN model is slightly better than the Kriging model when using a high number of POD basis vectors for regression. Moreover, the result presented in this paper demonstrates the suitability of the proposed MF-ROM for high-fidelity fixed value initialization to accelerate complex simulation.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.37-40
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• 2008

We have concentrated on the performance improvement of each part for durability, safety and cost of high pressure storage system for fuel cell vehicle so far. But for the mass production of fuel cell vehicle, it is necessary to evaluate durability and safety in system module. We built the standard to evaluate and collision safety of high pressure storage system for fuel cell vehicle, and could verify reliability of high pressure storage system.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.132-146
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• 2015

To develop tailored elementary, middle, and high school textbooks suitable for understanding the nuclear energy and radiation, quantitative and qualitative research was carried out in parallel, which included nine steps to ensure the validity of content and structure. The elementary, middle, and high school students wanted to acquire information used in their daily lives, including the definition of nuclear energy and radiation, principles and status of nuclear power generation, and information about irradiated food, medical radiation, and radiation in life. In the evaluation of the effects of textbook contents according to the educational requirements of each school level, high suitability frequencies (>80%) were shown for the human character, education goals, curriculum goals, evaluation method, and education time. At some levels, the high suitability frequencies (>70%) were shown for the education grade, education type, and textbook type.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.467-472
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• 2005

The characteristics of dynamic vibration are generally analyzed by an acceleration of a car body of high speed train and the acceleration can be applied to evaluation of running safety. The test of process and the analysis method about it are well explained on UIC Code 518 OR which is the spacial international standard about running safety and dynamic behavior on the line test for railway vehicle. Korean High Speed Train designed to operate at speed 350km/h has been tested on high speed line since it was developed in 2002 and it recorded the highest speed 352.4km/h at the 16th Dec. 2004 in Korea. This paper includes the analysis of running behavior of this train at speed 350km/h and also the analysis of dynamic safety is presented in it, extending to the range of high speed while the UIC 518 limit the speed below 200km/h.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.71-74
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• 2007

We have concentrated on the performance improvement of each part for durability, safety and cost of high pressure storage system for fuel cell vehicle so far. But for the mass production of fuel cell vehicle, it is necessary to evaluate durability and safety in system module. We built the standard to evaluate vibration and collision safety of high pressure storage system for fuel cell vehicle, and could verify reliability of high pressure storage system.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.266-271
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• 2004

Recently, consumers require products with high-reliability and high-safety. Risk management system and product safety become more important issue In view of product liability. This paper aims to propose a risk assessment system which can be applied to product with high-reliability and high-safety, and also show an empirical application of the proposed risk assessment system for the development of motorcycle helmets.

• Journal of the Korea Society of Computer and Information
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• v.22 no.11
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• pp.49-55
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• 2017

Recently, for safety of people, there are proposed so many technologies which detect density of people at the specific place or space. The representative technology for crowd density estimation was using image analysis method from CCTV images. However, this method had a weakness which could not be used and which's accuracy was lower at the dark or smog space. Therefore, in this paper, to solve this problem, we proposed a user density estimation system at closed space using high frequency and smart device. The system send inaudible high frequencies to smart devices and it count the smart devices which detect the high frequencies on the space. We tested real-time user density with the proposed system and ten smart devices to evaluate performance. According to the testing results, we confirmed that the proposed system's accuracy was 95% and it was very useful. Thus, because the proposed system could estimate about user density at specific space exactly, it could be useful technology for safety of people and measurement of space use state at indoor space.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.227-239
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• 2015

The thermal, mechanical, and neutronic performance of the metal alloy fast reactor fuel design complements the safety advantages of the liquid metal cooling and the pool-type primary system. Together, these features provide large safety margins in both normal operating modes and for a wide range of postulated accidents. In particular, they maximize the measures of safety associated with inherent reactor response to unprotected, doublefault accidents, and to minimize risk to the public and plant investment. High thermal conductivity and high gap conductance play the most significant role in safety advantages of the metallic fuel, resulting in a flatter radial temperature profile within the pin and much lower normal operation and transient temperatures in comparison to oxide fuel. Despite the big difference in melting point, both oxide and metal fuels have a relatively similar margin to melting during postulated accidents. When the metal fuel cladding fails, it typically occurs below the coolant boiling point and the damaged fuel pins remain coolable. Metal fuel is compatible with sodium coolant, eliminating the potential of energetic fuel-coolant reactions and flow blockages. All these, and the low retained heat leading to a longer grace period for operator action, are significant contributing factors to the inherently benign response of metallic fuel to postulated accidents. This paper summarizes the past analytical and experimental results obtained in past sodium-cooled fast reactor safety programs in the United States, and presents an overview of fuel safety performance as observed in laboratory and in-pile tests.

• Fire Science and Engineering
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• v.34 no.3
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• pp.85-90
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• 2020

The aim of this study is to identify ways to improve fire safety management of elementary and junior high schools, which can prevent potentially dangerous situations and establish a rapid response system for fire-related emergencies by analyzing existing fire safety management public institutions. We investigated the expertise, prevention ability, preparation ability, and operation form of fire safety managers working in elementary and secondary schools in Kangwon Province. A questionnaire composed of 26 items was completed by 238 fire safety managers. Results shows that the perception of fire safety management is considerably high, while the ability of the fire safety manager to prepare for and cope with an accident still needs improvement.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.63-68
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• 2011

Access-control of hazard zone in a steel manufacturing industry is studied in terms of safety management. Based on the results of risk evaluation for hazard zone, three risk zones with low, middle and high level are categorized. These zones have different color door and locking shape depending on their risk levels. At the high level, red door and key-based locking system are employed to accessed-controled path. Furthermore, tagout, lockout, interlock system for emergency stop, warning and flashing are also introduced. New standardized procedure of access-control for various hazard zones, which could help to greatly contribute to the prevention of accidents in advance, is proposed considering the risk level and the condition of given hazard zones. The standardized procedure of access-management suggested in this study will take an effective role as one of safety guide lines for hazardous workshop of manufacturing industries.