• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.88.2-88.2
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• 2011

The far-ultraviolet (FUV) continuum and spectral images of C IV and H2 emission lines for the region of Orion-Eridanus Superbubble (OES) are hereby presented and compared with the maps obtained in other wavelengths. While the region shows complex structures, consisting of hot gases and cold dust, a close examination reveals that the FUV emission in this region can be understood reasonably as the result of their interactions. We confirm the origin of most diffuse FUV continuum to be starlight scattered by dust, but we also find that the ionized gas also contributes 50-70% of the total FUV intensity in the regions of H_alpha arcs. We note the bright diffuse FUV continuum in the eastern part of the northern dust-rich region, and attribute it to the bright early-type stars more abundant in this region than in the west as the amount of dust itself does not seem to be much different across 'arc A' that separates the two regions. In addition, two P Cygni-type stars are identified in this eastern region and their peculiar spectral profiles around the C IV emission line are anifested in the scattered diffuse spectrum. Besides this, the C IV emission is generally enhanced at the boundaries of the hot X-ray cavities where thin dust regions are located, confirming the thermal interface nature of the origin of this cooling emission line. The morphology of the H2 emission shows a general correlation with dust extinction features but its intensity peaks are rather located in thin dust areas, off the peak dust regions. Furthermore, H2 emission is seen to be weak in the arc A region though the arc passes through the center of the dust-rich area. Hence, the H2 emission and dust features, together with those of X-ray and ion lines emissions, show stratified structure of arc A quite well, again confirming its thermal interface nature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.10
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• pp.649-657
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• 2017

A rupture in a high-pressure pipe causes the fluid in the pipe to be discharged in the atmosphere at a high speed resulting in a supersonic jet that generates the compressible flow. This supersonic jet may display complicated and unsteady behavior in general. In this study, Computational Fluid Dynamics (CFD) analysis was performed to investigate the compressible flow generated by a supersonic jet ejected from a high-pressure pipe. A Shear Stress Transport (SST) turbulence model was selected to analyze the unsteady nature of the flow, which depends upon the various gases as well as the diameter of the pipe. In the CFD analysis, the basic boundary conditions were assumed to be as follows: pipe of diameter 10 cm, jet pressure ratio of 5, and an inlet gas temperature of 300 K. During the analysis, the behavior of the shockwave generated by a supersonic jet was observed and it was found that the blast wave was generated indirectly. The pressure wave characteristics of hydrogen gas, which possesses the smallest molecular mass, showed the shortest distance to the safety zone. There were no significant difference observed for nitrogen gas, air, and oxygen gas, which have similar molecular mass. In addition, an increase in the diameter of the pipe resulted in the ejected impact caused by the increased flow rate to become larger and the zone of jet influence to extend further.

• Membrane Journal
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• v.13 no.4
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• pp.246-256
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• 2003

For the olefin recovery from polyolefin off-gas, the permeation behaviors of olefins and nitrogen were investigated through three kinds of PDMS membranes - cross-linked PDMS membranes, a polysiloxaneimide membrane, and oligo-PDMS modified PDMS membranes. Their pure gas permeabilities were measured as a function of operation temperature(-20 to $50^{\circ}C$) and pressure(1 to 25 atm) with ethylene($C_2\;H_4$), propylene($C_3\;H_6$), butylene($C_4\;H_8$), and nitrogen($N_2$) gases. The permeabilities of olefins and nitrogen highly depended upon the nature of PDMS membranes. Among these membranes, cross-linked PDMS membranes showed stable and high olefin/nitrogen selectivities over a wide operation pressure range and further study in various test conditions. Their permeability of olefin and nitrogen were governed by the condensation temperature(solubility selectivity) and plasticization, not the order of the size(diffusivity selectivity) of gases, which matched well with the general permeation behavior of rubbery polymeric membranes for condensable and non-condensable gases. With increasing feed pressure or decreasing feed temperature, the permeabilities of more condensible olefins increase highly, presumably due to high solubility and plasticization, but that of non-condensible nitrogen decreases slightly and thus, the selectivities of olefin/nitrogen increase highly.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.607-618
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• 2017

Harmful air pollutants are exhausted from the various industrial facilities including the coal-fired thermal power plants and these substances affects on the human health as well as the nature environment. In particular, nitrogen oxides ($NO_x$) and sulfur dioxide ($SO_2$) are known to be causative substances to form fine particles ($PM_{2.5}$), which are also deleterious to human health. The integrated system composed of selective catalytic reduction (SCR) and wet flue gas desulfurization (WFGD) have been widely applied in order to control $NO_x$ and $SO_2$ emissions, resulting in high investment and operational costs, maintenance problems, and technical limitations. Recently, new technologies for the simultaneous removal of $NO_x$ and $SO_2$ from the flue gas, such as absorption, advanced oxidation processes (AOPs), non-thermal plasma (NTP), and electron beam (EB), are investigated in order to replace current integrated systems. The proposed technologies are based on the oxidation of $NO_x$ and $SO_2$ to $HNO_3$ and $H_2SO_4$ by using strong aqueous oxidants or oxidative radicals, the absorption of $HNO_3$ and $H_2SO_4$ into water at the gas-liquid interface, and the neutralization with additive reagents. In this paper, we summarize the technical improvements of each simultaneous abatement processes and the future prospect of technologies for demonstrating large-scaled applications.

• Clean Technology
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• v.13 no.1 s.36
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• pp.64-71
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• 2007

The selection of a suitable adsorbent for removing organic sulfur compounds tetrahydrothiophene (THT) and t-butylmercaptan (TBM) from natural gas has been carried out. The saturation adsorption capacity for the sulfur compounds were determined by pulse adsorption method for a group of nanoporous materials, including Na-Y, Na-ZSM-5, Na,K-ET(A)S-10, Na-Mordenite, Na,K-Clinoptitolite, Ti/MCM-41, Ti/SBA-15 and amorphous titanosilicates. Among the materials tested, Na-Y and Na,K-ET(A)S-10 zeolites showed high adsorptive capacities for THT and TBM. The saturation capacity for THT on Na,K-ETS-10 was comparable with that on Na-Y zeolite, which is well known as an effective adsorbent. The capacity and adsorptivity for THT and TBM on Na,K-ETAS-10 were improved by an increase in crystallinity of Na,K-ETAS-10. An investigation of the competitive adsorption between THT and TBM from the breakthrough test using a simulated natural gas indicates that Na,K-ETS-10 selectively adsorbs THT. The breakthrough capacity for THT on Na,K-ETS-10 was 1.19 mmol/g. The results show that the high adsorption performance of Na.K-ETS-10 and Na,K-ETAS-10 is due to the highly exchanged cations in the zeolitic structure which exhibit the strong electrostatic interactions with organic sulfur compounds and their wide pore nature.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.102-102
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• 2016

Water, which is most abundant in Earth surface and very closely related to all forms of living organisms, has a simple molecular structure but exhibits very unique physical and chemical properties. Even though tremendous effort has been paid to understand this nature's core substance, there amazingly still lefts much room for scientist to explore its novel behaviors. Especially, as the scale goes down to nano-regime, water shows extraordinary properties that are not observable in bulk state. One of such interesting features is the formation of nanoscale bubbles showing unusual long-term stability. Nanobubbles can be spontaneously formed in water on hydrophobic surface or by decompression of gas-saturated liquid. In addition, the nanobubbles can be generated during electrochemical reaction at normal hydrogen electrode (NHE), which possibly distorts the standard reduction potential at NHE as the surface nanobubble screens the reaction with electrolyte solution. However, the real-time evolution of these nanobubbles has been hardly studied owing to the lack of proper imaging tools in liquid phase at nanoscale. Here we demonstrate, for the first time, that the behaviors of nanobubbles can be visualized by in situ transmission electron microscope (TEM), utilizing graphene as liquid cell membrane. The results indicate that there is a critical radius that determines the long-term stability of nanobubbles. In addition, we find two different pathways of nanobubble growth: i) Ostwald ripening of large and small nanobubbles and ii) coalescence of similar-sized nanobubbles. We also observe that the nucleation and growth of nanoparticles and the self-assembly of biomolecules are catalyzed at the nanobubble interface. Our finding is expected to provide a deeper insight to understand unusual chemical, biological and environmental phenomena where nanoscale gas-state is involved.

• Journal of the Korean Wood Science and Technology
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• v.10 no.2
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• pp.12-21
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• 1982

Red pine and Japanese larch (Larix leptolepis Gordon) grown in Korea have been the main species of coniferous resources in Korea. Especially, planting area of Japanese larch has been increased continueously in the recent years due to its superior plant type and rapid growth rate and its stocks reached approximately 4.32 million cubic meters at the present time. Although many research works have been done for the utilization of the larch wood in various ways, still many problems are existed in its chemical applications due to a large proportion of soluble extractives. In this study, chemical composition of larch extractives and chemical structure of its major component were analyzed. In order to identify the basic structure of major component, gas-liquid chromatography for separation of some completely methylated alditols as their acetates on a 3% - ECNSS-M on Gas Chrom Q. column was used. Proportion of extractives of Japanese larch wood was higher than that of other conifers and major component of the soluble extractives was arabinogalactan, a schematic structural formula which was presented in Figure 2. The molar ratio of arabinose and galactose was 1:4.5. The main chain of arabinogalactan was composed of 1,3 linked ${\beta}$-D-galactopyranose residues, each of which carried a side chain, attached to the C-6 positions. The exact nature of all of the side chains is not known, but the majority of these side chain was composed of 1, 6 linked ${\beta}$-D-galactopyranose residues, with 2~3 such units present per average chain. Some of the galactose units in the main chain had a residue of 3 - 0 - ${\beta}$-L-arabinopyranosyl-L-arabinofuranose. In addition, a few terminal residues of D-glucuronic acid also was confirmed, attached to C-6 position of the D-galactopyranose residue. It could concluded that the main structure of highly branched arabinogalactan from Japanese larch extractive was essentially the same as those of the other larch species.

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.47-54
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• 2006

The immediate causes of accidents are often identified as human error or technical failure but the investigation and analysis of the circumstances surrounding major industrial accidents such as Three Mile Island, Chemobyl and Kings Cross have revealed issues beyond the immediate causes. These issues relate to wider considerations of the safety culture. The safety culture of an organization is very complex and hard to study, but it is possible to examine norms that make up the culture. This paper focuses on environmental attitudes and actions among managerial and non-managerial workers in high risk industry such as chemical industries. The main purpose is to get a better understanding of safety culture and to develop measuring tool by examining their nature and strength and by analysing underlying factors that offer explanations for attitudinal differences.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.718-723
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• 1988

A yeast strain producing fruity-floral aroma was isolated from soil and identified as Hansenula saturnus var. saturnus. Glucose was found to be the best carbon source and sodium nitrate or phenylalanine as nitrogen source in terms of the nature and the intensity of the aroma produced by the isolated yeast. Seventeen compounds, mainly esters and alcohols, were identified in the ether-pentane extract of the culture broth by gas chromatography and/or coupled gas chromatography-mass spectrometry. Ethyl alcohol, isobutyl alcohol, isoamyl alcohol, phenethyl alcohol and their acetate esters together with ethyl caprylate were the major compounds in the aroma concentrate. Three unusual compounds, dibutyl disulfide, 3-methyl pentanoic acid and methyl pentanoate were also tentatively identified in the culture broth of the isolated yeast.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3832-3840
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• 2014

The rapidly aging population is also increasing the number of dementia patients rapidly. Studies have revealed the early signs of slowing progress. Therefore, dementia patient safety, continuous care, daily living, and health care are becoming more important. In this paper, a smart home care system using smart phones and Bluetooth communication technology was used to monitor the state of dementia patients of based on the results of grading dementia, health care of the dementia patients at home and provide for the safety of the system using motion sensors and gas leak sensors to respond to various emergency situations, such as fire, gas leak protection, and loitering. Using this system, the patient can stay longer in their home due to the nature of Korean culture before admission, while reducing the family's economical, physical and psychological burden and allowing the consultation of specialists through the system by building a database of individuals and providing professional service and specialty care referral agencies through the link.