• Convergence Security Journal
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• v.20 no.4
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• pp.197-208
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• 2020

Based on the network infrastructure advanced in the information knowledge society, the structure of computer net work is operated by establishing the composition of network in various forms that have secured the security. In case of computer network of national/public organizations, it is necessary to establish the technical and managerial securit y environment even considering the characteristics of each organization and connected organizations. For this, the im portance of basic researches for cyber training by analyzing the technical/managerial vulnerability and cyber threats based on the classification and map of cyber threats according to the characteristics of each organization is rising. T hus, this study aims to analyze each type of external/internal cyber threats to computer network of national/public o rganizations established based on the dualistic infrastructure network of internet and national information network, a nd also to present the cyber threat framework for drawing the elements of cyber security training, by drawing and analyzing the actual elements of cyber threats through the case-based scenario.

• Membrane Journal
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• v.31 no.6
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• pp.456-470
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• 2021

In this study, polyetherimide-based hollow fiber membranes were manufactured using the NIPS (nonsolvent induced phase separation) method. THF, Ethanol, and LiNO₃ were used as additives to control the morphology of the PEI-hollow fiber membranes. Furthermore, for the development of a high hydrogen separation membrane, the spinning conditions were optimized through the characterization of SEM and gas permeance. As a result, as the content of THF increased, the hydrogen/carbon dioxide selectivity increased. However, the permeance decreased due to the trade-off relationship. When ethanol was added, a finger-like structure was shown, and when LiNO₃ was added, a sponge structure was shown. In particular, in the case of a hollow fiber membrane with an optimized PDMS coating layer, the permeance was 40 GPU and the hydrogen/carbon dioxide selectivity was 5.6.

• Maritime Security
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• v.3 no.1
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• pp.115-140
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• 2021

The South China Sea is a significant maritime shipping route with abundant submarine and fishing resources. Over 40,000 ships pass through the South China Sea every year, constituting around 50% of global shipping and 66% of crude oil. In particular, 30% of Korea's import cargo and 90% of energy imports pass through this body of water. The US and China realized the significance of this sea area from early on and are embodying national interest through maritime security at the national strategic level by implementing the 'Indo-Pacific' and 'One Belt One Road' strategies, respectively. Such geopolitical conflicts are manifested in the 'freedom of navigation operations' by the US in the South China Sea. Despite its significance, there is a lack of studies in Korea on the freedom of navigation operations, and most previous studies only focus on analyzing international law and agreements. This article examines the origin and background of the strategic perception of the freedom of navigation operations and derives implications for the peace and security of the Korean Peninsula as the strategic competition between the US and China continues.

• Transactions of Materials Processing
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• v.31 no.1
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• pp.29-38
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• 2022

Recently, the composite material market is gradually growing. Various composite forming processes have been developed in order to reduce the production cost of the composite material. Unlike the conventional forming process, the microwave composite forming process has the advantage of reducing the processing time because the composite material is heated directly or indirectly at the same time. Due to this advantage, in this study, a double cantilever beam test was conducted with specimens manufactured by the microwave composite forming process. The purpose of this study was to compare mode-I energy release rate for specimens manufactured by prepreg compression forming and microwave composite forming processes. First, a microwave oven was proposed to conduct the microwave composite forming process. Double cantilever beam specimens were manufactured. After that, the double cantilever beam test was conducted to obtain the mode-I energy release rate. Mode-I energy release rates of specimens manufactured by the microwave composite forming and prepreg compression forming processes were then compared. As a result, mode-I energy release rates of specimens fabricated by the microwave composite forming process were similar to those fabricated with the prepreg compression forming process with a relatively reduced process time.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.25-29
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• 2021

This paper demonstrates the utility of the Ni-Pd and carbon-nanotube (Ni-Pd-CNT)-based nanoalloy to improve the α-Ga₂O₃ crystal quality using the halide-vapor-phase epitaxy (HVPE) method. As result, the overall thickness of the α-Ga₂O₃ epitaxial layer increased from a Ni electroless plating time of 40 s to 11 ㎛ after growth. In addition, the surface morphologies of the α-Ga₂O₃ epilayers remained flat and crack-free. The full-width half-maximum results of the X-ray diffraction analysis revealed that the ($10{\bar{1}}4$) diffraction patterns decreased with increasing nominal thickness.

• Composites Research
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• v.19 no.4
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• pp.1-6
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• 2006

The effects of aging on fatigue of PSF/AS4 laminates tvas studied using the new energy release rate analysis. The analysis by the variational mechanics has been useful in providing fracture mechanics interpretation of matrix microcracking in cross-ply laminates. This paper describes the changes of the critical energy release rate ${\Delta}Gmc$(microcracking toughness) about the variation of the aging period during fatigue loading. The master plot by modified Pans-law gives a characterization of a material system's resistance to microcrack formation. PSF/AS4 $[0/902]_s$ laminates were aged at four different temperatures based on the glass transition temperature for 60 days. At all temperatures, the toughness decreased with aging time. The decrease of the toughness at higher temperature was faster than at lower temperature. To assess the effects of aging on fatigue, the unaged laminates were compared with the laminates which were aged for 60 days at $170^{\circ}C$ near $180^{\circ}C\;T_g$. The slope of dD/dN versus A 6u, of the aged laminates was lower than that of the unaged laminates. There was a significant shift of the aged data to formation of microcracks at the lower values of ${\Delta}G_m$.

• Membrane Journal
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• v.33 no.3
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• pp.137-147
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• 2023

In this study, Br-PPO was developed by applying additive organic particles through a suspension polymerization synthesis method. The anion exchange membrane fuel cell system performance was evaluated using it to an anion exchange membrane. To improve the performance, organic ion exchange particles were prepared and added to the anion exchange membrane. Chemical structure analysis and synthesis were determined through FT-IR and NMR, and tensile strength and thermal stability were measured through TGA and UTM to determine whether it could be driven. Before the anion exchange membrane fuel cell test, the performance was evaluated by measuring the ion conductivity and ion exchange capacity. Finally, the Br-PPO-TMA-SDV (0.7%) anion exchange membrane with excellent ion conductivity and ion exchange capacity was introduced into the fuel cell system. Its performance was compared with FAA-3-50, a commercial membrane, to determine whether it could be introduced into a fuel cell system.

• Applied Chemistry
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• v.15 no.1
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• pp.17-20
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• 2011

A disposable light exposure detector kit has been developed by UV curing of a hydrogel material. The devised light exposure detector kit consisted of light sensitive structures, bottom plate, character sheet and sticky back plate. A light exposure detector kit has a serial light sensitive structures that contain various light sensitive dyes such as rhodamine and fluorescein. The light sensitive structure composed of UV curable hydrogel polymer material as a supporing material and photosensitive dye in a certain concentration. The fabrication procedure of the ligh exposure detector kit is very simple and fast due to UV curing procedure of a photopolymerizable hydrogel material such as poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) with a photosensitive dye. By the proposed fabrication method, various size and shape of a light exposure detector kit could be fabricated using a flexible elastomer mold. Due to a fast and inexpensive fabrication method, the light exposure detector kit could be use a single use for various industrial applications. According to light irradation, the light sensitive structure on a light exposure detector kit could be lose its color by decomposition of a photosensitive dye chemical in the structure. Thus the amount of the exposed light on a substrate could easily be recognised by changing color or transparency of the structure.

• Applied Chemistry
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• v.15 no.2
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• pp.113-116
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• 2011

A sensitive and selective determination method of Fe(II) ion by luminol-H₂O₂ system using a chelating reagent has been presented. A metal ion-chelating ligand complex such as Fe(II)-diethylenetriamine pentaacetic acid (DTPA) produced higher chemiluminescence (CL) intensity as well as longer lifetime in luminol-H₂O₂ system than metal exist as free ions. Furthermore, the catalytic activity of Cu(II) and Pb (II) complexes with chelating reagents in luminol-H₂O₂ system was lost since chelating reagents act as a masking agent although free Cu(II) and Pb(II) ions have high catalytic activity. On the optimized conditions, the calibration curve of Fe(II) ion was linear over the range from 1.0×10^-7 to 2.0×10^-5 M with correlation coefficient of 0.996. The detection limit was calculated to be 4.0×10^-8 M.

• Smart Media Journal
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• v.13 no.5
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• pp.19-25
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• 2024

The biggest type of behavior that prevents people with developmental disabilities from entering society is aggressive behavior. Aggressive behavior can pose a threat not only to the personal safety of the person with a developmental disability, but also to the physical safety of others. In this study, we propose a wearable system using a low-power processor. The proposed system uses an IMU (Inertial Measurement Unit) to analyze user behavior, and when attack behavior is not detected for a certain period of time through an LED array attached to the developed system, an interesting LED is displayed. By expressing patterns, we provide behavioral intervention through compensation to people with developmental disabilities. In order to implement a system that must be worn for a long time in a power-limited environment, we present a method to optimize performance and energy consumption across all stages, from data preprocessing to AI model application.