• Journal of the Korean Society for Heat Treatment
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• v.21 no.5
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• pp.244-250
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• 2008

This study has investigated the surface phase change, hardness variation, surface precipitates, nitrogen content and corrosion resistance in STS 431 (17Cr-2Ni-0.2C-0.01Nb) martensitic stainless steel after high temperature gas nitriding (HTGN) treatment at the temperature range between $1050^{\circ}C$ and $1150^{\circ}C$. The HTGN-treated surface layer appeared $Cr_2N$ of rod type, carbo-nitride of round type and fine precipitates in the austenite matrix. On the other hand the interior region where the nitrogen was not permeated, exhibited martensite phase. The surface hardness showed 250~590 HV, depending on the HTGN treatment conditions, while the interior martensitic phase represented 520 HV. The permeation depth of nitrogen increased with increasing the HTGN-treated temperature. The nitrogen concentration of the surface layer appeared approximately ~0.17% at $1100^{\circ}C$. On comparing the corrosion resistance between solution-annealed and HTGN-treated steels, the corrosion resistance of HTGN-treated steel was superior to that of solution-annealed specimens.

• Kyungpook Mathematical Journal
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• v.56 no.2
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• pp.431-450
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• 2016

In this paper, the existence, uniqueness, stability via continuous dependence and Ulam stabilities of nonlinear integro-differential equations with random impulses are studied under sufficient condition. The results are obtained by using Leray-Schauder alternative fixed point theorem and Banach contraction principle.

• Annual Conference of KIPS
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• 2020.05a
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• pp.431-434
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• 2020

본 논문에서는 악성코드탐지 기법으로 n-grams를 사용한 특징 추출을 통해 이미지 인식 분야에서 널리 쓰이는 Convolutional Neural Network로 학습하는 프레임워크를 제안한다. 윈도우즈 실행 파일의 PE 포맷에서 특징을 추출하여 6-grams 확률을 구하고 grayscale 을 통해 이미지로 변환한다. 이것을 기존에 연구된 탐지방법과 비교하여 우수함을 보인다. 학습에 사용된 데이터는 총 55,000개로 5-folds 교차검증을 하였으며 예측 정확도는 98.87%였다.

• Composites Research
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• v.31 no.4
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• pp.117-121
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• 2018

Various ceramic particulate such as TiC, $TiB_2$, $Al_2O_3$ reinforced SUS431 matrix composites were successfully fabricated by a novel liquid pressing infiltration process. Microstructures of the SUS431 composite were analyzed to determine manufacturability of composites. $Al_2O_3$-SUS431 composite had lots of defects due to poor wettability between the $Al_2O_3$ and steel matrix. On the other hand, TiC was uniformly dispersed in the SUS431 matrix than $TiB_2$ and $Al_2O_3$ due to good wettability and interfacial properties.

• Journal of Korean Association for Spatial Structures
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• v.12 no.2
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• pp.73-80
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• 2012

According to the global status of terroristic acts occurred from 2002 to 2010, 10,431(nearly 52.2%) of 19,946 cases have happened by bomb blasts, and 10,431(nearly 52.2%) of weapons used for terrorism were explosive substances Therefore, this study analyzed the terrorism risks of buildings according to height through FEMA 455 - rapid visual screening. As a result, the higher the building is, the higher the terror risk gets. It shows that total risk increases proportionally to buildings's height. In case of buildings over 100 meter high, the total risk is most affected by threat items. According to the risk of explosion associated with the scenario analysis, buildings over 100 meter high have high risks of Internal-Explosive.

• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.306-315
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• 1999

Purpose: We performed this study to evaluate the process of radiation induced apoptosis in A431 skin epithelial cancer cell line. Materials and Methods: Low to high dose radiation (0, 2, 5, 10, 25 Gy) was given to A431 cells by Cs-137 cell irradiator. Apoptosis was evaluated by cell morphology, dye exclusion test, and DNA laddering. Results: Cell viability decreased as the radiation dose increased. Number of apoptotic bodies increased as radiation dose increased. It increased most significantly at 12 hours after irradiation. Lactate dehydrogenase activity in culture medium increased according to radiation dose and time after irradiation. DNA ladders could be identified in irradiated cells, but, it had no correlation with radiation dose or time after irradiation. Conclusion: Radiation-induced apoptosis which was the main course of cell death in A431 cells could be analyzed quantitatively by counting apoptotic bodies under microscope. Apoptosis increased as radiation dose increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.430-431
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• 2005

• The Mathematical Education
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• v.32 no.4
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• pp.431-451
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• 1993

• Proceedings of the Safety Management and Science Conference
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• 1999.11a
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• pp.431-439
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.431-431
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• 2012

A compact tokamak reactor concept as a 14 MeV neutron source is desirable from an economic viewpoint for a fusion-driven transmutation reactor. LAR (Low Aspect Ratio) tokamak allows a potential of high "see full txt" operation with high bootstrap current fractions and can be used for a compact fusion neutron source. For the optimal design of a reactor, a radial build of reactor components has to be determined by considering the plasma physics and engineering constraints which inter-relate various reactor components and are constrained to use ITER physics and technology. In a transmutation reactor, the blanket should produce enough tritium for tritium self-sufficiency and the neutron multiplication factor, keff should be less than 0.95 to maintain sub-criticality. The shield should provide sufficient protection for the superconducting toroidal field (TF) coil against radiation damage and heating effects of the fusion neutrons, fission neutrons, and secondary gammas. In this work, characteristics of transmutation reactor based on LAR tokamak is investigated by using the coupled system analysis.