• Journal of Korea Foresty Energy
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• v.17 no.1
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• pp.36-46
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• 1998

The aim of this study was to develop the noise and vibration damping wood-based composites by using viscoelastic polymer materials. Polyvinylchloride(PVC) was plasticized with 20-140 phr bis(2-ethylhexyl) phthalate(DOP) and the dynamic tensile mechanical properties were measured at 110Hz and approximate temperature range -100 to 150$^{\circ}$ using a Rheovibron Instrument. The PVC/DOP blends were shown to be compatible in all proportions, and both T(E”$_{max}$) and T(tan${\delta}_{max}$) shifted to the lower temperature side as the DOP content increased. The vibration damping properties of wood/polymer composites were measured using the Rheovibron instrument in a bending mode. The composite damping factor(tan ${\delta}_{c}$) of wood /PVC-DOP/wood sandwich structure correlated with the loss factor and that of the coated structure correlated with the loss modulus(E”) of the polymer layer. In addition, the sandwich structure was found to be more effective in damping than the coated structure. The logarithmic decrement (${\Delta}$c) curve of a sandwich structure, which was determined by the free-free flexural vibration method was similar in shape to the tan ${\delta}_{c}$ curve.

• Corrosion Science and Technology
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• v.5 no.4
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• pp.129-136
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• 2006

High temperature corrosion behavior of AISI-type 316L stainless steel for the MCFC(molten carbonate fuel cell) bipolar application was studied by immersion test and penetration attack method in anode environment ($650^{\circ}C$, $Li_2CO_3/K_2CO_3=62/38$ mol%, $H_2/CO_2=80/20$ vol%) without or with different $CaCO_3$ content. Not only immersion test method but also morphological observation of samples in the carbonate melts are adopted as experimental methods. With aid of the morphological observation of cross section of samples immersed in a carbonate melt was possible to obtain penetration attack. The concentration effect of $CaCO_3$ inhibitor was investigated in order to verify the optimum concentration for practical application in MCFC stack operation. The corrosion rate in the presence of $CaCO_3$ was proven to be decreased as a function of $CaCO_3$ concentration. The corrosion rate in the presence of $CaCO_3$ was measured with a value of 6.9 mpy which is 2.4 times lower than that of inhibitor-free electrolyte. The cross section microscopy revealed that the internal penetration by oxidation in molten carbonate is very severe. In this case, the attack was occurred not only dissolution loss in the electrolyte by corrosion reaction but also weight gain through oxide layer by internal penetration.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.60-63
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• 1999

Application of reactive ion etching (RIE) technique to Ta-Al alloy thin film with a thickness of $1000{\AA}$ was studied. $CF_{4}$ gas could be used effectively to etch the Ta-Al alloy thin film. The etching rate in the thin film with Ta content of 50 mol% was about $67{\AA}/min$. NO selectivity between the Ta-Al alloy film and $SiO_{2}$ film was observed during the etching using the $CF_{4}$ gas. The etching rate of the $SiO_{2}$ layer was 12 times faster than that of the Ta-Al alloy thin film. It was also observed that photoresist of AZ5214 was more useful than Shiepley 1400-27 in RIE with the $CF_{4}$ gas.

• Carbon letters
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• v.22
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• pp.48-59
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• 2017

This study synthesized pure anatase carbon doped $TiO_2$ photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/$TiCl_4$. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The XRD patterns showed that the supported $TiO_2$ nanocrystals are typically anatase, polycrystalline and body-centered tetragonal in structure. The EDS and XPS results complemented one another and confirmed the presence of carbon species in or on the $TiO_2$ layer, and the XPS data suggested the substitution of titanium in $TiO_2$ by carbon. Instead of using calcination, PAN pyrolysis was used to control the carbon content, and the mesoporosity was tailored by the applied temperature. The supported $TiO_2$ nanocrystals prepared by pyrolysis at 300, 350, and $400^{\circ}C$ for 3 h on a stainless steel mesh were actual supported carbon doped $TiO_2$ nanocrystals. Thus, $PAN/DMF/TiCl_4$ offers a facile, robust sol-gel related route for preparing supported carbon doped $TiO_2$ nanocomposites.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.473-483
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• 1996

To protect the ozone layer, R22 will be replaced with HFCs. R407C is a leading candidate as alternative refrigerant for air conditioner due to its similar thermodynamic characteristics with R22. In replacing R22 with R407C, the compatibility with lubricating oil is of major concern. Polyol ester (POE) oil among the synthetic oils is considered to be the best lubricant for use with R407C because of good electrical properties and miscibility. However, lubricating ability of mixture of R407C/POE oil is lower than that of R22/mineral oil due to the production of acid by hydrolysis which causes corrosive wear. Therefore, to minimize water content, it is needed to develop a molecular sieve desiccant which is compatible with R407C and ester oil. This paper discusses (1) the change of properties of POE oil when current molecular seive is used, (2) the effects of POE oils and additives on durability of compressor. Through compressor life test and bench wear test, it was found that inadequate use of POE oils and additives may promote the deteriation of molecular sieve, resulting in decrease of durability of compressor.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.825-833
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• 2017

Strain IMCC26207 was isolated from the surface layer of Lake Soyang in Korea by the dilutionto-extinction culturing method, using a liquid medium prepared with filtered and autoclaved lake water. The strain could neither be maintained in a synthetic medium other than natural freshwater medium nor grown on solid agar plates. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain IMCC26207 formed a distinct lineage in the order Acidimicrobiales of the phylum Actinobacteria. The closest relative among the previously identified bacterial taxa was "Candidatus Microthrix parvicella" with 16S rRNA gene sequence similarity of 91.7%. Here, the draft genome sequence of strain IMCC26207, a freshwater actinobacterium, is reported with the description of the genome properties and annotation summary. The draft genome consisted of 10 contigs with a total size of 3,316,799 bp and an average G+C content of 57.3%. The IMCC26207 genome was predicted to contain 2,975 protein-coding genes and 51 non-coding RNA genes, including 45 tRNA genes. Approximately 76.8% of the protein coding genes could be assigned with a specific function. Annotation of the IMCC26207 genome showed several traits of adaptation to living in oligotrophic freshwater environments, such as phosphorus-limited condition. Comparative genomic analysis revealed that the genome of strain IMCC26207 was distinct from that of "Candidatus Microthrix" strains; therefore, we propose the name "Candidatus Limnosphaera aquatica" for this bacterium.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.487-487
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• 2009

One of the critical consumables in chemical mechanical polishing (CMP) is a specialized solution or slurry, which typically contains both abrasives and chemicals acting together to planarize films. In single abrasive slurry (SAS), the solid phase consists of only one type of abrasive particle. On the other hand, mixed abrasive slurry (MAS) consists of a mixture of at least two types of abrasive particles. In this paper, we have studied the CMP characteristics of mixed abrasive slurry (MAS) retreated by adding of $CeO_2$ abrasives within 1:10 diluted silica slurry (DSS). The slurry designed for optimal performance should produce reasonable removal rates, acceptable polishing selectivity with respect to the underlying layer, low surface defects after polishing, and good slurry stability. The modified abrasives in MAS are evaluated with respect to their particle size distribution, surface morphology, and CMP performances such as removal rate and non-uniformity. As an experimental result, we obtained the comparable slurry characteristics compared with original silica slurry in the viewpoint of high removal rate and low non-uniformity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.250-254
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• 1995

Isolated barley aleurone layers were used to examine response of (1-3)- and $(1-3,1-4)-{\beta}-glucanases{\;}to{\;}GA_3$. Protein content and levels of (1-3)- and $(1-3,1-4)-{\beta}-glucanases$ increased in the presense of added $GA_3$. However, (1-3)- and $(1-3,1-4)-{\beta}-glucanases$ showed different response to $GA_3$ in their production and secretion patterns. $(1-3,1-4)-{\beta}-glucanases$ showed higher increase in enzyme activity than $(1-3)-{\beta}-glucanase$ in the early stage of$GA_3$treatment. Secretion of enzyme by $GA_3$ into the surrounding medium was more enhanced in $(1-3,1-4)-{\beta}-glucanases$ than in $(1-3)-{\beta}-glucanase$, The differential response of the enzymes might be related to the physiological role of the enzymes in germination of barley grain.

• Journal of the Korean Ceramic Society
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• v.29 no.11
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• pp.888-892
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• 1992

The chemically induced grain-boundary migration has been studied in MgAl2O4 spinel under ZnO atmosphere. MgAl2O4 compacts been prepared by sintering powder mixture of Al2O3 and MgO at 1$600^{\circ}C$ for 60 h in air. The sintered MgAl2O4 has been heat-treated at 150$0^{\circ}C$ in a ZnO atmosphere. During the heat-treatment grain boundaries have become curved or faceted, and the total area of grain boundaries have increased. In the migrated region, the ZnO content is higher by 6 wt% than that in other regions, indicating that the migration was induced by addition of ZnO. In some shrinking grains, the faceted planes of different grain boundaries for the same grain are parallel to each other. This result provide an experimental support for the coherency strain energy in diffusion layer of the shrinking grain as being the major driving force. Calculated coherency strain energy of MgAl2O4 shows the maximum at {111} planes and the minimum at {100} planes. Although the minimum surface energy is at {111} planes, the faceted moving boundaries are expected to be {100} planes because of lowest driving force for the grain-boundary migration.

• Journal of the Korean GEO-environmental Society
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• v.17 no.2
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• pp.31-39
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• 2016

Vertical drain has usually been used to accelerate the consolidation of soft clay deposits with high moisture content. Busan thick clay deposits are subjected to artesian pressure from an aquifer in sand and gravel layers. However, effect of artesian pressure existing in drainage-installed soft ground on consolidation behaviors is not well known. This paper investigates the consolidation behavior of drainage-installed soft ground at the Nakdong river estuary with artesian pressure and without artesian pressure. A series of one-dimensional large size column test was carried out to find out the consolidation characteristics of clay. Test results indicated that total settlement of clay with artesian pressure was higher than that without artesian pressure because effective stress decreased due to upward flow. Dissipation rate of excess pore water pressure delayed and excess pore water pressure did not fully dissipate in clay layer with artesian pressure. Undrained shear strength of clay ground with artesian pressure was lower than that without artesian pressure.