• International Journal of Industrial Entomology and Biomaterials
• /
• v.25 no.2
• /
• pp.175-179
• /
• 2012

The present study is to develop the rearing method of Gryllotalpa orientalis. In total 429 of G. orientalis were collected from the field rearing cage ($25m^2$) in 2012. Its sex ratio was 1: 1.15(Female : Male). Survival rate of the mole crickets was 94.4~86.1% with the artificial diets formulated for the present study. Successful oviposition rate was 20, 20 and 80% for one, two and three pairs of adult crickets, respectively, from the indoor rearing. The mean number of hatchlings was $11.8{\pm}21.7$, $15.7{\pm}26.4$ and $25.8{\pm}38.8$, and the mean number of dead hatchlings 1.2, 1.7 and 1.2. The mortality of nymphs on horticultural soil and clay sand mixed with ocher was 18.3 and 10.0%, respectively. The mortality of nymphs in circular and rectangular cages was, respectively, 60 and 40%.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.37-44
• /
• 1998

The objective of this study is development of high strength lightweight concrete and application or structural use. For this, mix proportions for each strength level were selected from lab tests, and adapted to producing ready-mixed concrete in batcher plant. It was very important to prewet the lightweight aggregates sufficiently for producibility and also workability. Splitting tensile strength of high-strength lightweight concrete produced has lower values than that of normal weight concrete, but modulus of rupture and modulus of elasticity are not less than normal weight concrete. The strength reduction factor ($\lambda$) for sand-lightweight concrete make higher than 0.85 present in structures using high-strength lightweight concrete. And it was showed that not parabola distribution but triangular distribution of stress in compression zone.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.10a
• /
• pp.18-24
• /
• 1993

The purpose of this study is to evaluate the effect of substitution of silica fume and fly ash to the mortar mixed with 1:1 of cement/sand ratio on the physical properties. The changes of physical properties were observed through compressive strength, XRD, SEM, and porosity. As result, the compressive strength was excellent when silica fume was replaced with cement in the range of 10%. But the substituion of fly ash was not affect with improvement of compressive strength. Especially , the compressive strength showed the maximum value with 1047kg/$\textrm{cm}^2$ for the substitution of silica fume and fly ash of 10% and 5%, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.293-297
• /
• 2003

A series of laboratory experiments was conducted to investigate the fixation characteristics of poly(vinylalcohol)-poly(methacrylic acid)(PVA-PMAA) mixed solution on the soluble (equation omitted)-radionuclides. Using the potentiometric titration technique, it was found out that the PVA and PMAA in a solution form intermacromolecular complex. The mobilized portion of each radionuclide by water from sand surface treated with a fixative was measured by ${\gamma}$-ray spectroscopy, The mobilized portion of minor radionuclides such as $^{241}$ Am, $^{154}$ Eu, $^{155}$ Eu and $^{144}$ Ce were higher than those of $^{134}$ Cs and $^{137}$ Cs. The capability of PVA-PMAA system was better among the candidate solutions for the fixation of total (equation omitted)-radioactivity, $^{134,137}$Cs which is composed of more than 85 % of total ${\gamma}$-radioactivity could be fixed effectively by the PVA-PMAA solution.

• Proceedings of the KSRS Conference
• /
• 1998.09a
• /
• pp.110-115
• /
• 1998

Through the ISODATA method, the micro-landform of Julpo-Bay tidal flat was classified into mudflat, mixedflat, and sandflat using Landsat TM image. Each showed an apparent differences in its topographical characteristics and grain size composition. For example, mudflats are formed with flat faces and tidal channel of dissected gully. Its characteristics of grain size analysis that the grains have less than mean grain size 4 phi. Its sorting is bad (higher than 1 S.D.), and it showed strongly positive skewness. But sandflat is topographically flat without tidal channel. It has developed with ripple marks. According to the grain size analysis of deposits, the soil is coarse size with 90% of sand and its sorting is well(lower than 1 S.D.) Also, it showed strongly negative skewness. Mixed flat is in between mudflat and sandflat in its characteristics.

• Journal of Korea Foundry Society
• /
• v.6 no.1
• /
• pp.36-46
• /
• 1986

The effects of various kind of molds on cast structures were studied in Al-4.5% Cu and Al-8% Cu alloys. Five kinds of sand molds which were mixed with different binders and a metal mold were used. Density, dendrite arm spacing and dendrite arm length of the cast alloys were greatly affected by quantities and materials of mold binders. The macrostructures examined were entirely equiaxed grains with little influences of types of molds. It is possibly due to the separation of growing crystals from the mold wall at the inital stage of solidification.

• Nuclear Engineering and Technology
• /
• v.32 no.3
• /
• pp.205-213
• /
• 2000

A series of laboratory experiments was conducted to investigate the fixation characteristics of poly(vinylalcohol)-poly(methacrylic acid)(PVA-PMAA) mixed solution on the soluble ${\gamma}$- radionuclides. Using the potentiometric titration technique, it was found out that the PVA and PMAA in a solution form intermacromolecular complex. The mobilized portion of each radionuclide by water from sand surface treated with a fixative was measured by ${\gamma}$-ray spectroscopy. The mobilized portion of minor radionuclides such as 241Am, 154Eu, 155Eu and 144Ce were higher than those of 134Cs and 137Cs. The capability of PVA-PMAA system was better among the candidate solutions for the fixation of total ${\gamma}$-radioactivity. 134,137Cs which is composed of more than 85 % of total ${\gamma}$-radioactivity could be fixed effectively by the PVA-PMAA solution.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.1
• /
• pp.151-158
• /
• 2014

Asphaltenes are generally defined by their solubility when a light alkane, such as n-heptane or n-pentane, is mixed with crude oils or oil sand bitumen. However, this definition is nowadays not enough to understand their behaviors during oil recovery, transport, storage, and even refinery operation. Interestingly, the researches regarding asphaltenes have been vastly presented within last decade. This is because the production of heavy oils is becoming larger and asphaltenes are known to play an important role in the property changes of heavy oils. In this paper, the researches regarding molecular weight, aggregation behavior of asphaltenes are introduced and discussed. It is expected that analytical studies will be appeared continuously in the form of global collaboration in order to describe asphaltene molecules as close as possible based on their origin.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1512-1517
• /
• 2008

Laboratory column tests were conducted in this study using $Cl^-$ tracers on Jumunjin sand to analyze contaminant transport in mixed contaminated soils. Results obtained from clean soils and soils containing residual diesel verified heterogeneous distribution of residual diesel, and clear acceleration of solute movement. In addition, asymmetric breakthrough curves indicated development of immobile region where solute movement becomes stagnant and creates tailing phenomenon.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1109-1114
• /
• 2008

To investigate the effect of sample size on coefficient of consolidation of non-homogeneous soil, the result of a large size consolidation test using a huge undisturbed sample with $1200mm(D){\times}2000mm(H)$ in dimension is compared with that of oedometer test using undisturbed small sample. In addition, test results are compared with those of same test using remold sample. Experimental results show that, due to the lump of sand/silt was mixed in sample, the coefficient of consolidation of undisturbed samples have a difference for each tests. Whereas, the difference of coefficient of consolidation between remolded large and small samples is not found. Because sample size affects the test results, sample must be carefully selected for non-homogeneous soil.