• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.4
• /
• pp.349-357
• /
• 2019

Controlled low strength material(CLSM) has been developed using variety of material such as excavated soil, industrial by-product and industrial waste. But theses research limited at laboratory test and failed at commercialization. So in this paper evaluates CLSM used excavated soil characteristics such as flowability, bleeding rate, early strength for following process and 28day strength for re-excavatability. Also, various mix proportion of CLSM by water-binder ratio and soil-binder ratio were evaluated in laboratory. And derive the optimized CLSM mix proportion for using at field application test by movable batch plant. After applying CLSM at trench, evaluate core sample strength and excavatability by shovel, pickax and excavator for verify re-excavation. Furthermore, measure the level change after casting CLSM to inspect subsidence stability. As results of these assessments, not only confirmed the characteristics of CLSM at field but the fillability around pipe and subsidence stability.

• KSBB Journal
• /
• v.18 no.4
• /
• pp.261-265
• /
• 2003

Ibuprofen was analyzed by chiral high performance liquid chromatography. Retention behaviours of the standard mixtures of ibuprofen were investigated to obtain their acceptable resolution. A chromatographic column (3.9 ${\times}$ 300 mm) was packed by Kromasil CHI-TBB packings (10 $\mu\textrm{m}$) and n-hexane was used as a mobile phase with 0.1％ acetic acid and tert-butyl methyl ether. Isocratic elution of ibuprofen at 1.0 $m\ell$/min was performed by changing the mobile phase compositions. The experimental variables affecting the resolution were the compositions of mobile phase and chemical buffer (n-hexane and tert-butyl methyl ether). The resolution between the enantiomers were correlated into the several types of empirical equations including linear form, and their agreements between experimental data and calculated values were examined by the regression coefficient.

• Journal of the Korean Institute of Gas
• /
• v.4 no.3 s.11
• /
• pp.26-32
• /
• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power Therefore, there has been and still is a growing concern(safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline, especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion limitation of safety voltage and analysis of induction voltage.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.6
• /
• pp.309-316
• /
• 2016

In this study, sewage was fed with up flow direction into a reactor equipped with a screw to circulate media that had lower specific gravity than water. It was observed that the media in the reactor could be circulated by a screw with reverse flow of the sewage feeding from the top to the bottom direction. Under these conditions, concentrations of inflow and outflow pollutants were measured at the filtration unit. Experimental results revealed stable circulation of the media with a screw in the reactor. Circulation of the media in the reactor showed more efficiency in removing the pollutants (particulate matters and organics) than no circulation. The maximum removal efficiencies of suspended solid (SS), chemical oxygen demand (CODmn), and total phosphorus (T-P) were 96%, 72% and 65%, respectively. Improvements for SS, CODmn and T-P removals with circulation of media were 52.38%, 43.14% and 118.12% respectively, compared to those without circulation.

• Economic and Environmental Geology
• /
• v.35 no.3
• /
• pp.229-239
• /
• 2002

The objective of this study was to design an optimal electro-remediation system for TCE contaminated water using zero talent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the effects of electrode arrangement and the location of permeable iron barrier in the column on the TCE removal efficiency and iron corrosion process. In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive degradation of TCE was improved with simultaneous application of both ZVI and DC compared to that used ZVI only. The moot effective arrangement of electrode and ZVI for TCE removal from water was a column set with ZVI and cathode installed at the down gradient, respectively.

• Journal of Korea Foundry Society
• /
• v.27 no.1
• /
• pp.31-35
• /
• 2007

In order to develop the semi-solid forming technology for magnesium alloy the rheological and thixotropic behavior of Mg alloy slurry with varying shear rates and cooling rates was investigated and simulated with considering the viscosity based on microstructures and processing variables. The viscosity of slurry of Mg alloy (AZ91D) in semi-solid region was exponentially increased with a solid fraction, and was decreased with increasing a shear rate. In order to analyze precisely the rheological behavior, the ANYCAST program modified with the Carreau model and the different heat transfer coefficient between the cast and mold was used to simulate the flow behavior of Mg semi-solid slurry during the injection into a casting mold in a high pressure diecasting machine. The simulated rheological behavior of Mg alloy slurry was matched well with the experimental results.

• Resources Recycling
• /
• v.7 no.4
• /
• pp.43-49
• /
• 1998

We investigated the effects of the powder characteristics of various domestic iron oxides (${\alpha}Fe_2O_3$) on the magnetic properties of Sr-ferrites The particle size and the distribution of iron oxides were classified hy three different rerinning methods, and greatly a affected on the magn$\xi$tic prope$\pi$ies and the mmphology of Sr-ferntes. The agglomeration of Ruthner iron oxides and the large particles of Chemirite (CY) above $0.80{\mu}\textrm{m}$ were degraded the prope며es of Sr-fcrrites. The optimal magnetic prope$\pi$ies of Srt territes, showing 68.2 emu/g of saturation magnetization and 4300 Oe of intrinsic coerClvity, were achieved at the following c conditions; Chemirite (P2EP) iron oxides of $0.14{\mu}\textrm{m}$ molar ratio of 5.8. and calcination of $1150^{\circ}C$/1 hr.

• Journal of Korea Soil Environment Society
• /
• v.3 no.1
• /
• pp.21-30
• /
• 1998

The purpose of this study is to assess contaminant transfer and environmental impacts to the surroundings by inadequate control of USTs. Several methodologies can be used to approach for the site assessment depending on the appearance of contaminants on the site and their types. In this case study, randomized and/or triangle matrix techniques were used. As a result, the composition of materials in tank station were appeared in several state. From 1 to 1.5m depth, the soil was composed of reclaimed soils. And 1.8-3.5m depth, silty sand was appeared and about 4m, weathered soil was appeared. Based on the preliminary and actual site investigation by DPT methodologies on the width and depth of the site with analysis of BTEX and TPH, the contamination was found in this tank station and already distributed near areas. Finally, it was found that the hydroflow differences during the season affects the area and depth of contamination.

• Polymer(Korea)
• /
• v.26 no.5
• /
• pp.551-558
• /
• 2002

It was observed that adsorption characteristics of sulfonated fabric ion-exchanger for separating nickel ion from electroplating rinse water. Swelling ratio was increased by increasing degree of sulfonation and polarity of solvent. Ion-exchange capacity was also increased by increasing degree of sulfonation and showed 3.38 meq/g at 16% sulfonated ion-exchanger. There was little effects of pH. Adsorption equilibrium was attained within 10 min, and adsorption rate was 7.5 mg/min. Adsorption capacity was not changed after 7 cycles of regeneration process. Regeneration adsorption capacity was slightly decreased to 2.01 meq/g. It confirmed that durability of sulfonated fabric ion-exchanger was suitable for adsorption process. Adsorption equilibrium time was linearly increased by increasing L/D and adsorption capacity showed the ion exchange capacity within the range of 2.71 ∼ 3.01 meq/g in continuous process. Design of adsorption column could be possible for L/D<2. Under constant L/D condition, there is no little pH effect when rinse water is acidic solution, and operation condition of adsorption process was optimized under pH 5.

• Polymer(Korea)
• /
• v.31 no.2
• /
• pp.141-147
• /
• 2007

Dental properties of polymer composite loaded with hybrid filler of barium silicate (BaSi) and hydroxyapatite, which is a principal component of human bone material, were investigated. A visible light system was utilized to activate the acrylic resin matrix of the composite. Based on the experimental results, it was found that mechanical strength of the composite was consistently increased with an increase of BaSi content in the hybrid filler. And those value rose above the dental specification enough to apply for dental materials. However, abrasion resistance was slightly decreased with increasing BaSi content in the filler. Depth of cure value was 6 to 9 mm applicable for dental restoration irrelevant to hybrid filler composition. On the other hand, there was no strict trend between filler composition and polymerization shrinkage as well as degree of conversion.