• Journal of Powder Materials
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• v.22 no.5
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• pp.356-361
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• 2015

Fe-30 wt% TiC composite powders are fabricated by in situ reaction synthesis after planetary ball milling of (Fe, $TiH_2$, Carbon) powder mixture. Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe-30 wt% TiC composite powder compacts. Pressureless sintering is performed at 1100, 1200 and $1300^{\circ}C$ for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of $1050^{\circ}C$, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of $50^{\circ}C/min$, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts are not densified even after sintering at $1300^{\circ}C$ for 3 h, which shows a relative denstiy of 66.9%. Spark-plasma sintering at $1050^{\circ}C$ for 10 min exhibits nearly full densification of 99.6% relative density under the sintering pressure of 50 MPa.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1889-1894
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• 2012

A small-scale chamber test laboratory for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. Laboratory test which was simulated during construction stage was conducted. The vertical deflection of 4.43mm to 6.6mm, and the horizontal deflection of 5.49mm to 15.9 mm were measured during backfilling. In case of loading, the vertical deflection of 2.41mm to 8.69mm, and the horizontal deflection of 1.66mm to 2.53mm were measured. Its residual deflections were 1.40mm to 5.93mm for vertical and 1.66mm to 2.53mm for lateral. The vertical and horizontal deflecto of controlled low strength materials were smaller than that of sand backfill. Also, it was same trend for the measured surface settlement.

• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.25-33
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• 2004

The waste concrete produced by the process of the highway construction and management, has been crushed in-situ, and the waste aggregate has been experimentally used for anti-freezing layer and lean concrete. After testing the bearing capacity on anti-freezing layer, it was found that when the waste aggregates mixed with natural sand would be within the required gradations, the layer meets the requirements of limitation and the percentage to passing 2$\sim$20mm sieve increased by 5$\sim$13% because the flimsy mortars on aggregate were re-crushed by vibrated-roller compactor. The compressive strength of lean concrete using recycled aggregate was 71$\sim$85% of the natural coarce aggregate made, but nevertheless the recycled aggregates are applicable to the lean concrete because they largely exceeded the required strength, $57.5kgf/cm^2$.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.39-47
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• 2003

Cr thin films were deposited on photosensitive polyimide substrates by RF bias sputtering and DC sputtering and the interfaces between Cr thin film and polyimide were observed using TEM. When the polyimide surface was in-situ RF plasma cleaned at the RF power density of 0.13-2.12 $W/cm^2$, increasing of RF power density changed the morphology of polyimide surfaces from round dig to sharp shape, and surface roughness increased by anisotropic etching. The intermixed layer-like interfaces between Cr and polyimide were observed in the RF bias sputtered specimens. This interface seems to be formed due to the RF cleaning effect; the polyimide surface was RF plasma cleaned while RF power was increased to the setting point before Cr deposition.

• The KIPS Transactions:PartD
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• v.13D no.7 s.110
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• pp.985-996
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• 2006

As the internet technologies develop, the geographic information system environment is changing to the web-based service. Since geospatial information of the existing Web-GIS services were developed independently, there is no interoperability to support diverse map formats. In spite of the same geospatial information object it can be used for various proposes that is duplicated in GIS separately. It needs intelligent strategies for optimal replica selection, which is identification of replication geospatial information objects. And for management of replication objects, OMG, GLOBE and GRID computing suggested related frameworks. But these researches are not thorough going enough in case of geospatial information object. This paper presents a model of location service, which is supported for optimal selection among replication and management of replication objects. It is consist of tree main services. The first is binding service which can save names and properties of object defined by users according to service offers and enable clients to search them on the service of offers. The second is location service which can manage location information with contact records. And obtains performance information by the Load Sharing Facility on system independently with contact address. The third is intelligent selection service which can obtain basic/performance information from the binding service/location service and provide both faster access and better performance characteristics by rules as intelligent model based on rough sets. For the validity of location service model, this research presents the processes of location service execution with Graphic User Interface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.491-497
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• 2015

This paper reports an experimental study for evaluating the effect of temperature on the mode I, mode II and mixed-mode interlaminar fracture toughness of adhesive joints with a curved cross-section of filament-wound dome-separated composite pressure vessel. Mode I and mixed-mode interlaminar fracture toughness were evaluated using DCB specimens, while mode II interlaminar fracture toughness was determined using ENF specimens. $[{\pm}10^{\circ}]_6$, $[{\pm}27^{\circ}]_6$ and ($[{\pm}10^{\circ}]_3/FM73/[{\pm}27^{\circ}]_3$) winding specimens with the curved cross-section were considered. In-situ temperature environments were simulated with a range of $-30^{\circ}C-60^{\circ}C$ using an environmental chamber and furnace. Experimental results on the effect of temperature indicate that interlaminar fracture toughness tends to be high at low temperature and is degraded with increase in temperature. For specimen types, it was found that interlaminar fracture toughness of $[{\pm}10^{\circ}]_3/FM73/[{\pm}27^{\circ}]_3$ winding specimens considered as adhesive joints of dome and helical part was higher than other specimens.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.24-29
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• 1999

Naturally-occurring iron minerals, goethite, magnetite, and hydrogen peroxide were used to catalyze and initiate Fenton-like oxidation of silica sand contaminated with mixture of diesel and kerosene in batch system. Optimal reaction conditions were investigated by varying pH(3, 7), $H_2O_2$ concentration(0%, 1%, 7%, 15%, 35%), initial contaminant concentration(0.2, 0.5, 1.0 g-mixture of diesel and kerosene/ kg-soil), and iron mineral contents(1, 5, and 10 wt % magnetite or goethite). Contaminant degradations in silica sand-iron mineral-$H_2O_2$ systems were identified by determining total petroleum hydrocarbon(TPH) concentration. The optimal pH of the system was 3. The system which iron minerals were the only iron source was more efficient than the system with $FeSO_4$ solution due to lower $H_2O_2$ consumption. In case of initial contaminant concentration of 1g-contaminant/kg-soil with 5 wt % magnetite, addition of 0%, 1%, 7%, 15%, and 35% of $H_2O_2$ showed 0%, 24.5%, 44%, 52%, and 70% of TPH reduction in 8 days, respectively. When the mineral contents were varied 0, 1, 5, and 10wt%, removal of contaminants were 0%, 33.5%, 50%, and 60% for magnetite and 0%, 29%, 41%, and 53% for goethite, respectively. Reaction of magnetite system showed higher degradation than that of goethite system due to dissolution of iron and mixed presence of iron(II) and iron(III); however, dissolved iron precipitated on the surface of iron mineral and seemed to cause reducing electron transfer activity on the surface and quenching $H_2O_2$. The system using goethite has better treatment efficiency due to less $H_2O_2$ consumption. When cach system was mixed by shaker, removal of contaminants increased by 41% for magnetite and 30% for goethite. Results of this study showed catalyzed $H_2O_2$ system made in-situ treatment of soil contaminated with petroleum possible without addition of iron source since natural soils generally contain iron minerals such as magnetite and goethite.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1385-1390
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• 2012

Couple of laboratory for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. The optimum mix ratios for 4 cases with flowability and unconfined compressive strength were determined. The optimim mixing ratios were 25 to 45% of insitu soil, 30% of bottom ash, 10 to 20% of fly ash, 0 to 3% of crumb rubber, 3% of cement and 22% of water. Each mixture was satisfied the standard specification, minimum 20cm of flowability and 127 kPa of unconfined compressive strength. Two different curling methods, at room temperature and wet condition, were adopted. The average secant modulus(E50) was 0.07 to 0.08 * $q_u$. The compressive strength at wet condition showed 10% larger than at room temperature. The range of internal friction angle and cohesion for mixtures were 36.5o to 46.6o and 49.1 to 180 kPa, respectively. The mixture with crumb rubber(case 4) showed higher choesion and lower internal friction angle than the others. The pH of all the mixtures was over 12 which is strong alkine.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.557-575
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• 2020

Plasma blasting which is generated by high voltage arc discharge of electricity is applied to soil mass to improve permeability of soil and cleaning efficiency of oil contamination. A new high voltage generator was manufactured and three types of soil including silty sand, silty sand mixed with lime and silty sand mixed with cement were prepared. Small and large soil columns were produced using these types of soil and plasma blasting was performed within soil columns to investigate the variation of soil volume penetrated by fluid and permeability. Soil volume penetrated by fluid increased by 11~71% when plasma blasting was applied in soil. Although plasma blasting with low electricity voltage induced horizontal fracture and fluid penetrated along this weak plane, plasma blasting with high voltage induced spherical penetration of fluid. Plasma blasting increased the permeability of soil. Permeabilty of soils mixed with lime and cement increased by 450~1,052% with plasma blasting. Permeability of soil increased as discharge voltage increased when plasma blasing was applied once. However, several blastings with the same discharge voltage increase or decrease permeability of soil. Oil contaminated soil was prepared by adding diesel into soil artificially and plasma blasting was performed in these oil contaminated soil. Cleaning efficiency increased by average of 393% for soil located nearby the blasting and by average of 239% for soil located far from the blasting. Cleaning efficiency did not show any correlation with discharge voltage. All these results indicated that plasma blasting might be used for in-situ cleaning of oil contaminated soil because plasma blasting increased permeability of soil and cleaning efficiency.

• Journal of the Korean earth science society
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• v.32 no.2
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• pp.170-179
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• 2011

Fly ashes derived from coal fired power plants have unique chemical and mineralogical characteristics. The objective of this research was to study how indigenous bacteria affected heavy metal leaching in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Yeongdong seashore, Korea. The in-situ pH of ash pond seawater was 6.3-8.5. For this study, three sites of the ash pond were chosen to collect a sample of fly ash slurry. Three samples that had a mix of fly ash (0.4 L) and seawater (1.6 L) were collected at each site. First sample was autoclaved ($120^{\circ}C$, 2.5 atm), second one was inoculated with glucose to stimulate the microbial activity, and the last sample was kept in the natural condition. Compared with other samples including autoclaved and natural samples, the glucose added sample showed sharp increase in its alkalinity after 15 days, cation concentration change such as Ca, Mg, and K seemed to increase in early stage, and then decrease 15 days later in slurry solution of glucose added sample, and a possibly considerable decrease in $SO_4^{2-}$ in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data of this study is likely to be related to the activity of bacteria at the ash pond. The result may be used to understand about the characteristic of bacteria.