• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1289-1296
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• 2021

In this study, an electron-scattering device was fabricated to practically use the ultra-high dose rate electron beams for the FLASH preclinical research in Dongnam Institute of Radiological and Medical Sciences. The Dongnam Institute of Radiological and Medical Sciences has been involved in the investigation of linear accelerators for preclinical research and has recently implemented FLASH electron beams. To determine the geometry of the scattering device for the FLASH preclinical research with a 6-MeV linear accelerator, the Monte Carlo N-particle transport code was exploited. By employing the fabricated scattering device, the off-axis and depth dose distributions were measured with radiochromic films. The generated mean energy of electron beams via the scattering device was 4.3 MeV, and the symmetry and flatness of the off-axis dose distribution were 0.11% and 2.33%, respectively. Finally, the doses per pulse were obtained as a function of the source to surface distance (SSD); the measured dose per pulse varied from 4.0 to 0.2 Gy/pulse at an SSD range of 20-90 cm. At an SSD of 30 cm with a 100-Hz repetition rate, the dose rate was 180 Gy/s, which is sufficient for the preclinical FLASH studies.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4137-4141
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• 2021

As NPPs continue to operate, liquid waste continues to be generated, and containers are needed to store and transport them at low cost and high capacity. To transport and store liquid phase very low-level radioactive waste (VLLW), a container is designed by considering related regulations. The design was constructed based on the existing container design, which easily transports and stores liquid waste. The radiation shielding calculation was performed according to the composition change of barium sulfate (BaSO₄) using the Monte Carlo N-Particle (MCNP) code. High-density polyethylene (HDPE) without mixing the additional BaSO₄, represented the maximum dose of 1.03 mSv/hr (<2 mSv/hr) and 0.048 mSv/hr (<0.1 mSv/hr) at the surface of the inner container and at 2 m away from the surface, respectively, for a 10 Bq/g of ⁶⁰Co source. It was confirmed that the dose from the inner container with the VLLW content satisfied the domestic dose standard both on the surface of the container and 2 m from the surface. Although it satisfies the dose standard without adding BaSO₄, a shielding material, the inner container was designed with BaSO₄ added to increase radiation safety.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.807-819
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• 2019

Greybox fuzzing is known as an effective method to discover unknown security flaws reside in software and has been actively researched today. However, most of greybox fuzzing tools require an executable file. Because of this, a library, which cannot be executed by itself requires an additional executable file for greybox fuzzing. Generating such an executable file is challengeable because it requires both understanding of the library and fuzzing. In this research, we suggest the approach to generate an executable file automatically for a library and implement this approach as a tool based on the LLVM framework. This tool shows that executable files and seed files can be generated automatically by static/dynamic analysis of a unit test in the target project. A generated executable file is compatible with various greybox fuzzers like AFL because it has a common interface for greybox fuzzers. We show the performance of this tool as code coverage and discovered unknown security bugs using generated executable files and seed files from open source projects through this tool.

• Journal of Ocean Engineering and Technology
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• v.33 no.4
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• pp.313-321
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• 2019

The prediction of the hydrodynamic performance of a planing hull vessel is an important and challenging topic for computational fluid dynamic (CFD) applications to naval hydrodynamics. In this paper, the resistance and planing attitude analysis for a Fridsma hull, which is a prismatic planing hull, in still water are numerically studied using OpenFOAM. OpenFOAM is an open source code package based on C++ libraries and the finite volume method (FVM) for the discretization of the RANS equation. The volume of fluid method (VOF) is used to capture the water-air interface and the SST ${\kappa}-{\omega}$ model is used for the turbulence simulation. The overset mesh method is used to capture the large motion of the hull at higher speeds. Before the extensive analysis, uncertainty analyses using various time steps and grid sizes were performed for one ship speed case of Fn = 1.19. The results of the present study are compared with those of a model test, other CFD research, and Savitsky's empirical formula. The results of the present study, following the trend of other CFD results, slightly over predict the resistance and under predict the sinkage and, more significantly, the trim.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.9
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• pp.1173-1178
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• 2019

In this paper, we design a security management application module for an Excel VBA password file. You will set a password for the important VBA program file. If this password is lost, you set a new password. If you forgot the password after setting the password in the Excel VBA file, you will not be able to change the VBA source code. In this paper, we design a function to modify VBA file passwords conveniently. The VBA password modification module extracts VBA files from Excel files. The password can be modified by modifying specific field information in the extracted VBA program file. This allows you to modify the password for the VBA program file. The experiments were performed by implementing the contents proposed in this paper. As a result of the experiment, we can confirm that the password can be used by modifying the VBA file password.

• Coupled systems mechanics
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• v.8 no.4
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• pp.339-350
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• 2019

A numerical simulation of the incompressible multiphase hydraulic jump flow was performed to compare the interface prediction through the use of the three RANS turbulence models: $k-{\varepsilon}$, $RNGk-{\varepsilon}$ and SST $k-{\omega}$. A three dimensional no submerged hydraulic jump and a two dimensional submerged hydraulic jump were modeled. Both the geometry and the mesh were created using the open source Gmsh code. The project's geometry consists of a rectangular channel with length and height differences between the two dimensional and three dimensional simulations. Uniform hexahedral cells were used for the mesh. Three refining meshes were constructed to allow to verify simulation convergence. The Volume of Fluid (abbr. VOF) method was used for treatment of the air-water surface. The turbulence models were evaluated in three distinct set up configurations to provide a greater accuracy in the flow representation. In the two-dimensional analysis of a submerged hydraulic jump simulation, the turbulence model RNG RNG $k-{\varepsilon}$ provided a better interface adjust with the experimental results than the model $k-{\varepsilon}$ and SST $k-{\omega}$. In the three-dimensional simulation of a no-submerged hydraulic jump the k-# showed better results than the SST $k-{\omega}$ and RNG $k-{\varepsilon}$ capturing the height and length of the ledge with a better fit with the experimental results.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.176-189
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• 2019

This paper presents a feasibility study for producing the medical isotope $^{99m}Tc$ using the hazardous and currently wasted radioisotope $^{99}Tc$. This can be achieved with the nuclear resonance fluorescence (NRF) phenomenon, which has recently been made applicable due to high-intensity laser Compton scattering (LCS) photons. In this work, 21 NRF energy states of $^{99}Tc$ have been identified as potential contributors to the photo-production of $^{99m}Tc$ and their NRF cross-sections are evaluated by using the single particle estimate model and the ENSDF data library. The evaluated cross sections are scaled using known measurement data for improved accuracy. The maximum LCS photon energy is adjusted in a way to cover all the significant excited states that may contribute to $^{99m}Tc$ generation. An energy recovery LINAC system is considered as the LCS photon source and the LCS gamma spectrum is optimized by adjusting the electron energy to maximize $^{99m}Tc$ photo-production. The NRF reaction rate for $^{99m}Tc$ is first optimized without considering the photon attenuations such as photo-atomic interactions and self-shielding due to the NRF resonance itself. The change in energy spectrum and intensity due to the photo-atomic reactions has been quantified using the MCNP6 code and then the NRF self-shielding effect was considered to obtain the spectrums that include all the attenuation factors. Simulations show that when a $^{99}Tc$ target is irradiated at an intensity of the order $10^{17}{\gamma}/s$ for 30 h, 2.01 Ci of $^{99m}Tc$ can be produced.

• Journal of the Korean Geotechnical Society
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• v.37 no.9
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• pp.13-24
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• 2021

Recently, attempts have been made to detect fouling patterns in the ground using Ground Penetrating Radar (GPR) during the maintenance of gravel ballast railway tracks. However, dealing with GPR signal data obtained with a large amount of noise in a site where complex ground conditions are mixed, often depends on the experience of experts, and there are many difficulties in precise analysis. Therefore, in this study, a numerical modeling technique that can quantitatively simulate the GPR signal characteristics according to the degree of fouling of the gravel ballast material was proposed using python-based open-source code gprMax and RSA (Random sequential Absorption) algorithm. To confirm the accuracy of the simulation model, model tests were manufactured and the results were compared to each other. In addition, the identification of the fouling layer in the model test and analysis by various test conditions was evaluated and the results were analyzed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.4
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• pp.779-791
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• 2021

Common web services have been continuously targeted by hackers due to an access control policy that must be allowed to an unspecified number of people. In order to cope with this situation, companies regularly check web vulnerabilities and take measures according to the risk of discovered vulnerabilities. The risk of these web vulnerabilities is calculated through preliminary statistics and self-evaluation of domestic and foreign related organizations. However, unlike static diagnosis such as security setting and source code, web vulnerability check is performed through dynamic diagnosis. Even with the same vulnerability item, various attack results can be derived, and the degree of risk may vary depending on the subject of diagnosis and the environment. In this respect, the predefined risk level may be different from that of the actual vulnerability. In this paper, to improve this point, we present a web vulnerability risk assessment model based on the attack result centering on the cyber kill chain.

• International Journal of Computer Science & Network Security
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• v.21 no.2
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• pp.171-180
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• 2021

Currently, hospitals and medical practices have a large amount of unstructured information, gathered in time at each ward or practice by physicians in a wide range of medical branches. The data requires processing in order to be able to extract relevant information, which can be used to improve the medical system. It is useful for a physician to have access to a patient's entire medical history when he or she is in an emergency situation, as relevant information can be found about the patient's problems such as: allergies to various medications, personal history, or hereditary collateral conditions etc. If the information exists in a structured form, the detection of diseases based on specific symptoms is much easier, faster and with a higher degree of accuracy. Thus, physicians may investigate certain pathological profiles and conduct cohort clinical trials, including comparing the profile of a particular patient with other similar profiles that already have a confirmed diagnosis. Involving information technology in this field will change so the time which the physicians should spend in front of the computer into a much more beneficial one, providing them with the possibility for more interaction with the patient while listening to the patient's needs. The expert system, described in the paper, is an application for medical diagnostic of the most frequently met conditions, based on logical programming and on the theory of probabilities. The system rationale is a search item in the field basic knowledge on the condition. The web application described in the paper is implemented for the ward of pathological anatomy of a hospital in Romania. It aims to ease the healthcare staff's work, to create a connection of communication at one click between the necessary wards and to reduce the time lost with bureaucratic proceedings. The software (made in PHP programming language, by writing directly in the source code) is developed in order to ease the healthcare staff's activity, being created in a simpler and as elegant way as possible.