A semantic approach to improving machine readability of a large-scale attack graph

Automation in cyber security can be achieved by using attack graphs. Attack graphs allow us to model possible paths that a potential attacker can use to intrude into a target network. In particular, graph representation is often used to increase visibility of information, but it is not effective when a large-scale attack graph is produced. However, it is inevitable that such a voluminous attack graph is generated by modeling a variety of data from an increasing number of network hosts. Therefore, we need more intelligent ways of inferring the knowledge required to harden network security from the attack graph, beyond getting information such as possible attack paths. Ontology technology enables a machine to understand information and makes it easier to infer knowledge based on relational facts from big data. Constructing ontology in the domain of attack graph generation is a prerequisite for increasing machine intelligence and implementing an automated process. In this paper, we propose a semantic approach to make a large-scale attack graph machine readable. The approach provides several benefits. First, users can obtain relational facts based on reasoning from a large-scale attack graph, and the semantics of an attack graph can provide intuition to users. In addition, intelligence-based security assessment can be possible using the obtained ontological structures. By improving the machine readability of an attack graph, our approach could lead to automated assessment of network security.

     

Development of a web-based emergency preparedness plan system in Korea

The chemical industry treats a huge quantity of hazardous and harmful flammable liquids, combustible gases and toxic materials. Therefore, there is a high potential for fires, conflagrations, explosions and toxic leaks. To minimize the possibility of such hazards, the Korean government has been enforcing an EPP (Emergency Preparedness Plan) in accordance with the Toxic Chemicals Controls Act since 1996. However, 70% of the targeted small and medium-sized enterprises are struggling with the independent implementation of EPP, and 30% of the EPP grades being used are not amenable to approval and further application. As a result, we have developed a web-based emergency preparedness plan system. The main purpose of the program is to provide a safety management system to each facility in order to enable accidents to be prevented and accidents to be immediately controlled. The program also helps government or related agencies to control a number of accidents that occur in small companies throughout the entire country.     

Hydrogen Isotope Separation in Confined Nanospaces: Carbons,Zeolites, Metal–Organic Frameworks,and Covalent Organic Frameworks

One of the greatest challenges of modern separation technology is separating isotope mixtures in high purity. The separation of hydrogen isotopes can create immense economic value by producing valuable deuterium (D) and tritium (T), which are irreplaceable for various industrial and scientific applications. However, current separation methods suffer from low separation efficiency owing to the similar chemical properties of isotopes; thus, high‐purity isotopes are not easily achieved. Recently, nanoporous materials have been proposed as promising candidates and are supported by a newly proposed separation mechanism, i.e., quantum effects. Herein, the fundamentals of the quantum sieving effect of hydrogen isotopes in nanoporous materials are discussed, which are mainly kinetic quantum sieving and chemical‐affinity quantum sieving, including the recent advances in the analytical techniques. As examples of nanoporous materials, carbons, zeolites, metal–organic frameworks, and covalent organic frameworks are addressed from computational and experimental standpoints. Understanding the quantum sieving effect in nanospaces and the tailoring of porous materials based on it will open up new opportunities to develop a highly efficient and advanced isotope separation systems.     

Successive laser-induced breakdowns in atmospheric pressure air and premixed ethane–air mixtures

Two successive focused laser pulses are employed to experimentally simulate laser-induced breakdown plasmas at high repetition rates. We find that energy absorption of the second laser pulse by the plasma produced by the first laser pulse is enhanced slightly when the time interval between the pulses is shorter than several tens of nanoseconds but falls to almost zero when the time interval is between a few hundreds of nanoseconds and several tens of microseconds. This behavior is attributed to gas heating by the first breakdown event. In premixed ethane–air mixtures, we identify another strong reduction in the second laser pulse absorption when this pulse coincides with the heat released by combustion, typically milliseconds after the first laser pulse. The fuel–air equivalence ratio (?) and base flow speed are also varied in this study. The results show that the window of reduced absorption coinciding with heat release due to combustion is narrowed when the base flow speed is increased, and also under fuel lean and fuel rich conditions. These results suggest that the use of pulsed high frequency laser breakdowns for premixed combustion stabilization is optimized when laser pulse repetition rates below a certain frequency (e.g., 500 Hz at the conditions that ? is 1 and the base flow speed is 4.9 m/s) to maximize laser energy coupling and for improved anchoring of the flame base.     

Using hydrogen activated by microwave plasma vs. molecular hydrogen for hydrogen storage in tungsten disulfide inorganic nanotubes

In this work we investigate the inorganic nanotubes of layered tungsten disulfide, as material for hydrogen storage. These nanotubes may allow hydrogen to be either chemi- or physisorbed inside their crystalline structure (in between the layers), inside hollow core of nanotubes, on the surface or in the open interstitial pore spaces of nanotubes' powder mesh. While exposure to molecular hydrogen was found to have measurable but limited absorption rate – up to 0.13 wt.%, the exposure to hydrogen activated by microwave (MW) plasma resulted in much higher value of adsorbed hydrogen of ∼1 wt.%. These observations could be attributed to more effective interaction of activated vs. molecular hydrogen with nanotubes surface due to the strong chemisorption of activated hydrogen compared to weaker physisorption of molecular hydrogen. We report here the results of such exposures and analyze the absorption and diffusion of hydrogen by different methods: adsorption–desorption curves obtained by pressure–composition–temperature isotherm measurements, and hydrogen depth profiles measured by Secondary Ion Mass Spectroscopy. We found that 5 min exposure to MW plasma at 400 W and 60 Torr (causing local heating up to ∼100 °C) results in substantial hydrogen retention, though some etching of the substrate material may occur during such treatment.     

Synthesis and preliminary gas permeation studies of a tubular NaA zeolite membrane (NZM)

Different from traditional seeded method, NaA zeolite membranes (NZMs) were prepared by in situ synthesis onto the inner side of porous α-alumina tubular supports in a hydrothermal synthesis reactor. The influences of pretreatment of porous tubular support, temperature, time, and synthetic cycle for the synthesis of the zeolite membranes were investigated. The operating conditions were optimized. Characterization of the membranes by scanning electron microscopy and X-ray diffraction showed that the crystalline materials on the inner surface of the porous α-alumina tubes were NaA-type zeolite. Single- and binary-gas permeation tests were conducted. Single-component permeabilities of hydrogen and nitrogen through the NZM changed slightly when the transmembrane pressure difference varied from 80 to 420?kPa. Its selectivity for H₂ relative to N₂ was about 5.3, which was greater than that of the Knudsen diffusion. The separation factors of binary gases H₂/N₂ and H₂/CO₂ at 473?K were 3.9 and 5.7, respectively, again exceeding the Knudsen diffusion level. The separation of binary gases suggests that the NaA-type zeolite membranes on α-alumina substrate were defect free and able to provide molecular sieving. The results demonstrate that the unseeded synthetic method presented in this work is successful and reliable.     

A system dynamics approach for modeling construction workers’ safety attitudes and behaviors

Construction accidents are caused by an unsafe act (i.e., a person's behavior or activity that deviates from normal accepted safe procedure) and/or an unsafe condition (i.e., a hazard or an unsafe mechanical or physical environment). While there has been dramatic improvement in creating safer construction environments, relatively little is known regarding the elimination of construction workers’ unsafe acts. To address this deficiency, this paper aims to develop a system dynamics (SD)-based model of construction workers’ mental processes that can help analyze the feedback mechanisms and the resultant dynamics regarding the workers’ safety attitudes and safe behaviors. The developed model is applied to examine the effectiveness of three safety improvement policies: incentives for safe behaviors, and increased levels of communication and immersion in accidents. Application of the model verifies the strong potential of the developed model to provide a better understanding of how to eliminate unsafe acts, and to function as a robust test-bed to assess the effectiveness of safety programs or training sessions before their implementation.