• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.1-5
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• 1989

This study was carried out by using laboratory data to calculate Soil Moisture Control Section (SMCS) for medium textured topo-sequential soils derived from porphyry in Milyang area. The soils studied were characterized by loam to silty clay loam, and the moisture content at -1/3 bar in the solum ranged around 21.06% to 32.42%. The moisture contents per centimeter of soil layer within a solum calculated at field capacity (FC) ranged from 0.11cm to 0.19cm. The upper boundaries of SMCS of the soils calculated on the basis of FC as the water content at -1/3 bar, ranged from 16.2cm to 21.2cm and the lower boundaries from 44.4cm to 63.8cm, and the depth of SMCS were from 27.7cm to 42.6cm in the soil profiles. The Bongsan soil on the summit had shallower in the boundaries and narrower in the depth of SMCS than the soils on side-slopes or on valley.

• Journal of Sericultural and Entomological Science
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• v.3
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• pp.37-43
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• 1963

This experimental work was carried out to know the best method in producing the root stock effectively. The major experimental work was carried out by using Kairyo-Nezumigaeshi, and the comparative works were carried out by using Ichi-Hei, Kairyo-Nezumigaeshi, Ro-Soh, Yongchon-Chuwoo and Suwon No. 4. Results obtained from the test are as follows. 1. The larger size of the branch burried, the better live ratio and the quality of the sapling was found, and there was no significant difference between the top part and bottom part of the branch from the point of view of the ratio, but it was found that the top part showed better live ratio and quality. Mean time there was no difference in live ratio between the two sprouts root-stock type and the three sprouts root-stock type. 2. When the live ratio and sapling quality was compared from the aspect of the new root development, the heavy and medium developed root type showed better result than the poor developed one. 3. For the ambushing depth test of the root-stock, the root-stock which was painted with paraffin on the top and exposed in the air was found to have best live ratio. Mean time, even though paraffin was not painted all the top of the root-stock, the one which was exposed the top of it or the one ambushed with thin soil layer, showed better live ratio than the one deep ambushed. 4. There was difference for the live ratio between the perpendicularly ambushed root-stock and the lied ambushed mot-stock, but the former method showed better sapling quality. 5. The soil nature did not show any difference for the live ratio between the sand loam and clay loam, but the former one showed better sapling quality. 6. There was no difference live ratio between the mulberry varieties, but Yongchon-Chuwoo showed best sapling quality. 7. The grafted sapling production cost was 2.30 won and cattage sapling cost was 1.61 won.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.323-345
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• 2019

It is essential to predict ground conditions ahead of a tunnel face in order to successfully excavate tunnels using a shield TBM. This study proposes a forward prediction method for a mixed soil ground and/or a ground containing core stones by using electrical resistivity and induced polarization exploration. Soil conditioning in EPB shield TBM is dependent upon the composition of mixed soils; a special care need to be taken when excavating the core-stoned soil ground using TBM. The resistivity and chargeability are assumed to be measured with four electrodes at the tunnel face, whenever the excavation is stopped to assemble one ring of a segment lining. Firstly, the mixed ground consisting of weathered granite soil, sand, and clay was modeled in laboratory-scale experiments. Experimental results show that the measured electrical resistivity considerably coincides with the analytical solution. On the other hand, the induced polarization has either same or opposite trend with the measured resistivity depending on the mixed ground conditions. Based on these experimental results, a method to predict the mixed soil ground that can be used during TBM tunnel driving is suggested. Secondly, tunnel excavation from a homogeneous ground to a ground containing core stones was modeled in laboratory scale; the irregularity of the core stones contained in the soil layer was modeled through random number generation scheme. Experimental results show that as the TBM approaches the ground that contains core stones, the electrical resistivity increases and the induced polarization fluctuates.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.3
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• pp.155-164
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• 2019

In this study, the soil-structure interaction(SSI) effect on the seismic response of LNG storage tanks was investigated according to the type of foundation. For this purpose, a typical of LNG storage tank with a diameter of 71m, which is constructed on a 30m thick clay layer over bedrock was selected, and nonlinearity of the soil was taken into account by the equivalent linearization method. Four different types of foundations including shallow foundation, piled raft foundation, and pile foundations(surface and floating types) were considered. In addition, the effect of soil compaction in group piles on seismic response of the tank was investigated. The KIESSI-3D, which is a SSI analysis package in the frequency domain, was used for the SSI analysis. Stresses in the outer tank, and base shear and overturning moment in the inner tank were calculated. From the comparisons, the following conclusions could be made: (1) Conventional fixed base seismic responses of outer tank and inner tank can be much larger than those of considering the SSI effect; (2) The influence of SSI on the dynamic response of the inner tank and the outer tank depends on the foundation types; and (3) Change in the seismic response of the structure by soil compaction in the piled raft foundation is about 10% and its effect is not negligible in the seismic design of the structure.

• Journal of Korean Society on Water Environment
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• v.35 no.2
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• pp.145-151
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• 2019

The purpose of this study was to investigate treatment characteristics of diatomite filtration, that would allow water recovery from biologically-treated effluent for reuse. Diatomite, Celpure 100, and acid clay were used as filter-aids, with a support filter manufactured from polyethylene (PE), and polypropylene (PP). This pre-coating process using diatomite filter-aids, is used in the filtration range of pressure filters, and has consistently provided high-quality separation. The results showed that variations in average removal efficiency of SS, and T-P from biologically treated effluent by the diatomite-coated PE filter, were approximately 82.2 ~ 88.9 % and 4.8 ~ 21.1 %, respectively. T-P treatment efficiency of the PP filter pre-coated with diatomite and $Celpure^{(R)}100$ at $57.64g/m^2$, was approximately $24{\pm}10%$ and $40{\pm}15%$ on average, respectively. Particle size distribution of secondary effluent varied from 0.05 to $200{\mu}m$, and $d_{50}$ value was $20.76{\mu}m$. The size distribution of particles in the diatomite filtrate ranged from 1.26 to $101.1{\mu}m$ when pre-coated with diatomite filter-aid, at a content of $57.64g/m^2$. Diatomite filter aids, i.e., the particles that form the pre-coating layer, capture very fine particles as well as macromolecules, owing to their complex structure with numerous fine microscopic pores, and surface properties. The filtration process using diatomite and $Celpure^{(R)}100$ as filter aids, has been successfully applied, to recover water from sewage for reuse. The disadvantage of the process, is that the particle size of the filter-aid is spent, because of pressurization.

• Journal of Soil and Groundwater Environment
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• v.27 no.spc
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• pp.51-63
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• 2022

In this study, the TPH(Total Petroleum Hydrocarbon) contamination and microbial ecological characteristics in petroleum-contaminated site were investigated through the correlation among the vertical TPH contamination distribution of the site, the geochemical characteristics, and the indigenous microbial ecology. The high TPH concentration showed in the vicinity of 3~4 m or less which is thought to be affected by vertical movement due to the impervious clay layer. In addition, the TPH concentration was found to have a positive correlation with Fe²⁺, TOC concentration, and the number of petroleum-degrading bacteria, and a negative correlation with the microbial community diversity. The microbial community according to the vertical distribution of TPH showed that Proteobacteria and Firmicutes at the phylum level were dominant in this study area as a whole, and they competed with each other. In particular, it was confirmed that the difference in the microbial community was different due to the difference in the degree of vertical TPH contamination. In addition, the genera Acidovorax, Leptolinea, Rugoshibacter, and Smithella appeared dominant in the samples in which TPH was detected, which is considered to be the microorganisms involved in the degradation of TPH in this study area. It is expected that this study can be used as an important data to understand the contamination characteristics and biogeochemical and microbial characteristics of these TPH-contaminated sites.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.589-601
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• 2021

Artificial recharge technology is a method for solving problems such as groundwater level drop and ground subsidence caused by groundwater withdrawal. This study investigated the applicability of using the hydraulic conductivity of an aquifer to predict injection test results for aquifer restoration. Pumping and injection tests were performed under the same conditions as those for the artificial injection facility located in Icheon, Gyeonggi-do. The hydraulic conductivity of the aquifer, which plays a decisive role in restoring the groundwater level, was derived from the pumping test. A numerical model of a simplified on-site aquifer was constructed, and a transient analysis was applied with the same conditions as the pumping test. The correlation between the measured and the resulting model values is strong (R² = 0.78). The injection test was performed in a sedimentary layer composed of silt sand and clay sand. From the results of the injection test, an empirical formula was derived using Theim's formula, which is a common well analysis solution to determine the parameters of the aquifer from time-level data. The model values from the empirical formula have a high degree of correlation (R² = 0.99) with measured values. Under specific conditions, for areas where it is difficult to conduct an injection test, the formula from this study, which relies on the hydraulic conductivity of the aquifer determined through the pumping test, may be used to predict reliable injection rates for groundwater restoration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5C
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• pp.209-218
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• 2010

In residual soils, large particles such as rock fragments or gravel are surrounded by sand or clay. The strength of such granular mixtures can be controlled by the concentration of fine or coarse grains. The percentage by weight, size or shape of gravel in the mixture that can control the strength of the mixture has not been clearly determined for various granular mixtures. In this study, the effect of dispersed gravels on the shear characteristics of sand was evaluated. Large and small gravels were inserted in the middle of each layer with moist Nakdong River sand and compacted into a cylindrical sample with five equal layers. Embedded gravel ratios by weight were 0, 3, 9, and 14%. After consolidation, a series of undrained triaxial compression tests was performed on Nakdong River sand with dispersed gravels. Maximum deviator stresses of the Nakdong River sand with large gravels decrease up to 38% as a percentage of embedded gravels increases. Such strength degradation decreases as a confining pressure increases. The maximum deviator stress increases as the percentage by weight of small gravel increases; at 3 or 9% of gravel weight it slightly increases but at 14% of gravel weight it increases up to 34%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.174-180
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• 2023

Porcelain (white ware, celadon ware) coated with a ferrous sulfate and ferrous/cobalt sulfate was sintered at 1250℃. The specimens were investigated by HR-XRD, FE-SEM, HR-EDS, and UV-vis spectrophotometer. Through X-ray rietveld quantitative analysis, quartz and mullite were found to be the main phases for white ware, and mullite and plagioclase were found to be the main phases for celadon ware. When the pigment of ferrous/cobalt sulfate was applied, were identified as an andradite phase for celadon ware and a spinel phase for the white ware, and the amorphous phase, respectively. The L^* value, which was the brightness of the specimen, was 72.01, 60.92 for white ware and celadon ware, respectively. The ferrous and ferrous/cobalt pigment coated porcelain had L^* values of 44.89, 52.27 for white ware and celadon ware, respectively; with a^* values of 2.12, 1.40, an d at b^* values of 1.45 and 13.79. As for the color of the specimens, it was found that the L^* value was greatly affected by the white ware, and the b^* value differed greatly depending on the clay. It was thought to be closely related to the production of the secondary phase such as Fe₂O₃ and andradite phase produced in the surface layer.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.1
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• pp.2913-2924
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• 1973

This study was to investigate the drying mechanism of stratified soil by investigating 'effects of the upper soil on moisture loss of the lower soil and vice versa' and at the same time by examining how the drying progressed in the stratified soils with bare surface and with vegetated surface respectively. There were six plots of the stratified soils with bare surface($A_1- A_6$ plot) and the same other six plots($B_1- B_5$ plot), with vegetated surface(white clover). These six plots were made by permutating two kinds of soils from three kinds of soils; clay loam(CL). Sandy loam(SL). Sand(s). Each layer was leveled by saturating sufficient water. Depth of each plot was 40cm by making each layer 20cm deep and its area. $90{\times}90(cm^2)$. The cell was put at the point of the central and mid-depth of the each layer in the each plot in order to measure the soil moisture by using OHMMETER. soil moisture tester, and movement of soil water from out sides was cut off by putting the vinyl on the four sides. The results obtained were as follow; 1. Drying progressed from the surface layer to the lower layer regardless of plots. There was a tendency thet drying of the upper soil was faster than that of the lower soil and drying of the plot with vegetated surface was also faster than that of the plot with bare surface. 2. Soil moisture was recovered at approximately the field capacity or moisture equivalent by infiltration in the course of drying, when there was a rainfall. 3. Effects of soil texture of the lower soil on dryness of the upper soil in the stratified soil were explained as follows; a) When the lower soil was S and the upper, CL or SL, dryness of the upper soils overlying the lower soil of S was much faster than that overlying the lower soil of SL or CL, because sandy soil, having the small field capacity value and playing a part of the layer cutting off to some extent capillary water supply. Drying of SL was remarkably faster than that of CL in the upper soil. b) When the lower soil was SL and the upper S or CL, drying of the upper soil was the slowest because of the lower SL, having a comparatively large field capacity value. Drying of CL tended to be faster than that of S in the upper soil. c) When the lower soil was CL and the upper S or SL, drying of the upper soil was relatively fast because of the lower CL, having the largest field capacity value but the slowest capillary conductivity. Drying of SL tended to be faster than that of S in the upper soil. 4. According to a change in soil moisture content of the upper soil and the lower soil during a day there was a tendency that soil moisture contents of CL and SL in the upper soil were decreased to its minimum value but that of S increased to its maximum value, during 3 hours between 12.00 and 15.00. There was another tendency that soil moisture contents of CL, SL and S in the lower soil were all slightly decreased by temperature rising and those in a cloudy day were smaller than those in a clear day. 5. The ratio of the accumulated soil moisture consumption to the accumulated guage evaporation in the plot with vegetated surface was generally larger than that in the plot with bare surface. The ratio tended to decrease in the course of time, and also there was a tendency that it mainly depended on the texture of the upper soil at the first period and the texture of the lower soil at the last period. 6. A change in the ratio of the accumulated soil moisture consumption was larger in the lower soil of SL than in the lower soil of S. when the upper soil was CL and the lower, SL and S. The ratio showed the biggest figure among any other plots, and the ratio in the lower soil plot of CL indicated sligtly bigger than that in the lower soil plot of S, when the upper soil was SL and the lower, CL and S. The ratio showed less figure than that of two cases above mentioned, when the upper soil was S and the lower CL and SL and that in the lower soil plot of CL indicated a less ratio than that in the lower soil plot of SL. As a result of this experiments, the various soil layers wero arranged in the following order with regard to the ratio of the accumulated soil moisture consumption: SL/CL>SL/S>CL/SL>CL/S$\fallingdotseq$S/SL>S/CL.