• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.49-56
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• 2010

This study investigated how the surface of Al-12wt.%Si alloy modified by the plasma electrolytic oxidation process (PEO). The PEO process was performed in an electrolyte with sodium hexametaphsphate as a conducting salt, and the effect of ammonium metavanadate on variations in the morphology of electrochemically generated oxide layers on the alloy surface was investigated. It is difficult to form a uniform passive oxide layer on Al alloys with a high Si content due to the differences in the oxidation behavior of the silicon-rich phase and the aluminum-rich phase. The oxide layer covered the entire surface of the Al-12WT.%Si alloy uniformly when ammonium metavanadate was added to the electrolyte. The oxide layer was confirmed as a mixture of $V_2O_3$ and $V_2O_5$ by XPS analysis. In addition, the oxide layer obtained by the PEO process with ammonium metavanadate exhibited a black color. Application of this surface modification method is expected to solve the problem of the lack of uniformity in the coloring of oxide layeres caused by different oxidation behaviors during a surface treatment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.3
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• pp.43-53
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• 2007

Internet becomes more and more popular, and most companies and institutes use web services for e-business and many other purposes. With the explosion of Internet, the occurrence of cyber terrorism has grown very rapidly. Simulation is one of the most widely used method to study internet worms. But, it is quite challenging to simulate very large-scale worm attacks because of various reasons. In this paper, we propose a hybrid modeling method for RCS(Random Constant Spreading) worm simulation. The proposed hybrid model simulates worm attacks by synchronizing modeling network and packet network. So, this model will be both detailed enough to generate realistic packet traffic, and efficient enough to model a worm spreading through the Internet. Moreover, our model have the capability of dynamic updates of the modeling parameters. Finally, we simulate the hybrid model with the CodeRed worm to show validity of our proposed model for RCS worm simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.231-238
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• 2022

Mine detection has been mainly studied with images of the forward-looking sonar. Forward-looking sonar assumes the propagation path of the sound wave as a straight path, creating the surrounding images. This might lead to errors in the detection by ignoring the refraction of the sound wave. In this study, we propose a mine localization method that can robustly identify the location of mines in an underwater environment by considering the refraction of sound waves. We propose a method of estimating the elevation angle of arrival of the target echo signal in a single receiver, and estimate the mine location by applying the estimated elevation angle of arrival to ray tracing. As a result of simulation, the method proposed in this paper was more effective in estimating the mine localization than the existing method that assumed the propagation path as a straight line.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.3
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• pp.115-120
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• 2022

A brown ring (hereinafter referred to as BR) on the inner surface of a quartz glass crucible used in the manufacturing process of a silicon ingot for semiconductor wafers was studied. BR is 20~30 ㎛ in size and has an asymmetric brown ring shape. The size and distribution of BR were different depending on the crucible location, and the size and distribution of BR were the largest and most abundant in the round part with the highest crucible temperature during Si ingot growth. BR contains cristobalite, which has a higher coefficient of thermal expansion than quartz glass, so it is considered that surface cracks appear. The color development of BR and pin holes are presumed to be due to oxygen vacancies.

• Korean Journal of Psychosomatic Medicine
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• v.30 no.2
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• pp.179-186
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• 2022

Objectives : This study aimed to examine the moderating effects of reasons for living on the relationship between depression and suicidal ideation among psychiatric patients. Methods : Patients were recruited from the department of psychiatry of university hospital. A total of 137 participants completed self-report questionnaires assessing depression (Beck Depression Inventory), suicidal ideation (Ultra-Short Suicidal Ideation Scale) and reasons for living (The Reasons for Living Inventory). Results : Among 4 sub-scales of the reasons for living inventory, survival and coping beliefs, fear of death and social disapproval, and future expectation moderated the relationship between depression and suicidal ideation. Conclusions : The results suggest that the reasons for living can work as a protective factor on the relationship between depression and suicidal ideation among psychiatric patients.

• Journal of Software Assessment and Valuation
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• v.17 no.1
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• pp.31-40
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• 2021

Plagiarism refers to the act of using the original data as if it were one's own without revealing the source. The plagiarism of source code causes a variety of problems, including legal disputes. Plagiarism in software projects is usually determined by measuring similarity by comparing every pair of source code within two projects. However, blindly comparing every pair has been a huge computational burden, causing a major factor of not using tools of better accuracy. If we can only compare pairs that are probable to be clones, eliminating pairs that are impossible to be clones, we can concentrate more on improving the accuracy of detection. In this paper, we propose a method of selecting highly probable candidates of clone pairs by pre-classifying suspected source-codes using a machine-learning model called code2vec.

• Hanyang Medical Reviews
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• v.33 no.1
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• pp.10-16
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• 2013

Follicular helper T cells (Tfh) play a significant role in providing T cell help to B cells during the germinal center reaction, where somatic hypermutation, affinity maturation, isotype class switching, and the differentiation of memory B cells and long-lived plasma cells occur. Antigen-specific T cells with IL-6 and IL-21 upregulate CXCR5, which is required for the migration of T cells into B cell follicles, where these T cells mature into Tfh. The surface markers including PD-1, ICOS, and CD40L play a significant role in providing T cell help to B cells. The upregulation of transcription factor Bcl-6 induces the expression of CXCR5, which is an important factor for Tfh differentiation, by inhibiting the expression of other lineage-specific transcription factors such as T-bet, GATA3, and RORγt. Surprisingly, recent evidence suggests that CD4 T cells already committed to Th1, Th2, and Th17 cells obtain flexibility in their differentiation programs by downregulating T-bet, GATA3, and RORγt, upregulating Bcl-6 and thus convert into Tfh. Limiting the numbers of Tfh within germinal centers is important in the regulation of the autoantibody production that is central to autoimmune diseases. Recently, it was revealed that the germinal center reaction and the size of the Tfh population are also regulated by thymus-derived follicular regulatory T cells (Tfr) expressing CXCR5 and Foxp3. Dysregulation of Tfh appears to be a pathogenic cause of autoimmune disease suggesting that tight regulation of Tfh and germinal center reaction by Tfr is essential for maintaining immune tolerance. Therefore, the balance between Tfh and Tfr appears to be a critical peripheral tolerance mechanism that can inhibit autoimmune disorders.

• Korean Journal of Clinical Pharmacy
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• v.33 no.2
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• pp.128-134
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• 2023

Background: This systematic review and meta-analysis aimed to evaluate the efficacy and cardiovascular safety of romosozumab compared with placebo. Methods: Randomized controlled trials (RCTs) were searched from Medline, EMBASE, Cochrane Central, and Web of Science until July 2022. Primary outcomes included the change in bone mineral density (BMD) from baseline at month 6. The secondary outcomes were the change of bone turnover markers (N-terminal propeptide of type 1 procollagen (P1NP); C-terminal telopeptide of type 1 collagen (CTX)) from baseline at month 3, and the incidence of cardiovascular adverse events for the total follow-up period. Results: A total of 7 RCTs on 8,370patients were included. Romosozumab showed better effects in improving BMD in both lumbar spine and femoral neck at month 6 (standardized mean difference, SMD 2.20 [95% CI: 1.89-2.52], SMD 0.63 [95% CI: 0.41-0.86]). In contrast to placebo, romosozumab significantly increased PINP levels and reduced CTX levels at month 3 (SMD 0.93 [95% CI: 0.65-1.22], SMD -1.03 [95% CI: -1.23~ -0.82]. However, there was no significant difference in the composite incidence of cardiovascular adverse events and major adverse cardiovascular events (OR 1.16 [95% CI: 0.82-1.65], OR 1.08 [95% CI: 0.75-1.56]). Conclusion: This analysis showed that romosozumab significantly improved BMD compared to placebo and was beneficial for change in bone turnover markers. There is no significant difference in the incidence of cardiovascular adverse events compared to placebo.

• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.1-7
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• 2024

The utilization of Unmanned Aerial Vehicles (UAVs) is expanding in various industries such as logistics, manufacturing, and transportation. However, to operate a large number of UAVs, it is imperative to first plan a secure and efficient self-configuring communication network for UAVs. In this study, we proposed a method for planning a secure and efficient UAV self-configuring communication network using Voronoi diagrams in the following three steps: 1) generating Voronoi diagrams using obstacles, 2) selecting obstacles to consider for path generation, and 3) planning the optimal path and outputting the path. The real-time feasibility of using the proposed method for planning optimal communication paths for a realistic number of UAVs was experimentally validated.

• Journal of Powder Materials
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• v.31 no.1
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• pp.43-49
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• 2024

In this study, a core-shell powder and sintered specimens using a mechanically alloyed (MAed) Ti-Mo powder fabricated through high-energy ball-milling are prepared. Analysis of sintering, microstructure, and mechanical properties confirms the applicability of the powder as a sputtering target material. To optimize the MAed Ti-Mo powder milling process, phase and elemental analyses of the powders are performed according to milling time. The results reveal that 20 h of milling time is the most suitable for the manufacturing process. Subsequently, the MAed Ti-Mo powder and MoO₃ powder are milled using a 3-D mixer and heat-treated for hydrogen reduction to manufacture the core-shell powder. The reduced core-shell powder is transformed to sintered specimens through molding and sintering at 1300 and 1400℃. The sintering properties are analyzed through X-ray diffraction and scanning electron microscopy for phase and porosity analyses. Moreover, the microstructure of the powder is investigated through optical microscopy and electron probe microstructure analysis. The Ti-Mo core-shell sintered specimen is found to possess high density, uniform microstructure, and excellent hardness properties. These results indicate that the Ti-Mo core-shell sintered specimen has excellent sintering properties and is suitable as a sputtering target material.