• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.362-375
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• 1991

Background and Necessity of the study : For more than 20 years, the soil engineering reserach group of Chonnam National University has been performing the deformation analysis of soft clayey foundation, since the University is located near the south-western coast of Korean Peninsulla, along which tide reclamation works have been under proaressing. Associsted with the fact mentioned above, the researchers have been developing a computer program in order to carry out deformation analysis of soft foundation since early 1980. Case-studies : In this research, the Biot's equation was selected as the governing equation coupled with several constitutive models including original and modified Cam-clay models, elasto-viscoplastic model, Lade's model etc. The anisotropy of soi1 can be considered in this program. To validate the accuracy of the computer program developed a couple of case-studies were performed. These include the pilot banking, sand drain considering smear effect and compound foundation reinforced with sheet pile into soft foundation.i) The pilot banking Good results could be acquired by assuming banking load as the body force composed of finite element mesh rather than equivalent concentrated load.ii) The sand drain Due to smear, the delay of consolidation was remarkable at the early stsge. so safety for the failure of foundation should be checked for the initial step of consolidation. iii) The compound foundation Accurate results were obtained by introducing the joint element method for the soft foundation reinforced with sheet pile into soiㅣ.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.49-59
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• 2010

Earthquake-induced liquefaction on saturated loose sand is well known in the world. Since Saemangeum Dike Project has a plan to be reclaimed with dredged sand on wide river, possibility of liquefaction should be checked. Section Dongjin5 was selected to evaluate possibility of liquefaction. Estimating method follows as 1) determination of PL value with SPT results, passing curve, and soil properties, 2) prediction for maximum earthquake acceleration, 3) calculation for FL value on depth with Korean specification for highway bridges, 4) visualization for possibility of liquefaction on all of project area with GIS 5) comparison with Japanese specification for highway bridges, Youd and Idriss method, and Andrus and Stokoe II method for verification, 6) ascertainment for the potential liquefaction with cyclic triaxial test. 7) establishing for countermeasure if needed. From the results, even though most of area covered with sand, no potential liquefaction exists except some areas. Those need to soil improvement with grout or attaching measurement on substructure.

• Geomechanics and Engineering
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• v.10 no.1
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• pp.1-19
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• 2016

This paper presents the results of an intensive experimental investigation on cyclic behavior of various sands and structural materials interface. Comprehensive measurements of the horizontal displacement and shear stresses developed during testing were performed using an automated constant normal load (CNL) cyclic direct shear test apparatus. Two different particle sizes (0.5 mm-0.25 mm and, 2.0 mm-1.0 mm) of sands having distinct shapes (rounded and angular) were tested in a cyclic direct shear testing apparatus at two vertical stress levels (${\sigma}=50kPa$, and 100 kPa) and two rates of displacement ($R_D=2.0mm/min$, and 0.025 mm/min) against various structural materials (i.e., steel, concrete, and wood). The cyclic direct shear tests performed during this investigation indicate that (i) the shear stresses developed during shearing highly depend on both the shape and size of sand grains; (ii) characteristics of the structural materials are closely related to interface response; and (iii) the rate of displacement is slightly effective on the results.

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.200-208
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• 2011

The neutron fluence measurement and evaluation technology is very important for material irradiation test. The most essential technology in this study is the neutron irradiation evaluation method using a fluence monitor. The fluence monitors were fabricated with metal wires of the purity ${\geq}$ 99.9%, whose dimensions were 0.1mm diameter, about 3 mm length, and around 150-200 ${\mu}g$ mass range. Three wire samples (Fe, Ni, Ti) were prepared for one irradiation aluminum capsule. Five capsules were irradiated in the OR5 hole of the HANARO reactor at 30 MW power for about 25 days. After irradiation tests, radiation activities were measured with the high purity germanium (HPGe) detector. The reaction rates were calculated by using the measured radiation activity data, and then neutron fluence were obtained from the reaction rates and the weighted neutron cross section with calculated neutron spectrum at the fluence monitor position.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.2
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• pp.93-98
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• 1976

The present paper is a part of a study aimed at gaining information on the origin, mode of deposition, and characteristics of volcanic soils in Jeju. Volcanic activity of Jeju island has extremely influenced on the formation of various soils. Polysequum phenomenon of soils is one of outstanding soil genesis in Jeju. The typical polysequum soils was collected and analyzed by morphological, physico-chemical, mineralogical and micromorphological approaches The results are as follows: 1. The soils consists of polysequa, A and B horizons from volcanic ashes, unconsolidated volcanic sand layer and B(I) horizons from residual basalts. 2. The lithological discontinuity is also very distinct; silt loam from volcanic ashes, sand (II) from volcanic sand and clayey (III) from basalts. 3. Volcanic sand layer seems to be influenced by lava flow. The properties of it are similar to volcanic ashes rather than beneath residuum in micromorphological aspects. In micromorphological, this layer is gradually changed into soils. 4. Dominant clay minerals are allophane in A and B horizons from volcanic ashes and kaoline, vermiculite and illite from residual basalts. 5. The soils are not developed. There is no formation of argillic horizon in subsurface layers.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.323-328
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• 1997

Runoff of phorate, soil insecticide, were measured under simulated rainfall conditions in field using small test plot$(120\;cm{\times}120\;cm)$ at the loam area and loamy sand area. Fish acute toxicity tests were performed with runoff water to elucidate its toxicological effect on organisms in ecosystem. The average concentrations of phorate in runoff water from loam and loamy sand soil were 11.3 ppb and 4.8 ppb, respectively. However, there was no significant concentration difference between the heavy and the light rain. With loam soil, average runoff rates were 1.31 and 0.18%, while with loamy sand soil those were 0.48 and 0.012% under the heavy and the light rain conditions, respectively. Total average runoff rate was 0.50%. With killifish, no mortality was observed in runoff water from loamy sand soil, whereas half of the population was dead in runoff water from loam soil when it was diluted to 54.4% content.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.1
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• pp.37-45
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• 1985

To define the amount of consumptive use of upland crops, the moisture consumption characters were investigated with different soil moisture content by soil properties(loam, sandy loam, sand) at the experimental farm of Kon-Kuk University from April 20 to July 20 1984. The results obtained are summarized as follows; 1. Total moisture consumption under bare soil condition had an order of loam> sandy loam> sand and showed an order of pF 1.5> pF2. 1> pF 2.7 by re-irrigation point and the average during the experimental period (92days) was 435. 9mm and the daily average moisture consumption was 4. 7mm. 2. The moisture consumption characters of bare soil plot obtained showed that the amount of irrigation water per one time and the days of intermission increased and, on the contrary, the times of irrigation and the total amount of irrigation water decreased by the increment of re-irrigation point in the same soil 3. Total moisture consumption of spring cabbage under open cultivation showed 528.6 rim in maximum and had an order of loam> sandy loam> sand. In the aspect of rc-irrigation point, it had an order of pFl. 5> pF 2.1> pF 2.7. In case the planning basic year was taken into account, the amount of irrigation water needed for open cultivation was 456. 3 mm and its average daily moisture consumption was 6. 2mm. 4. Total moisture consumption of summer cucumber under open cultivation showed 635. 8mm in maximum and had an order of loam> sandy loam> sand. In the aspect of re-irrigation point, it had an order of pF 1.5> pF2. 1> pF2. 7 In case the planning basic year was taken into consideration, the amount of irrigation water was 516. 9mm and its aversge daily moisture consumption was 6. 5mm. 5. The result of cabbage cultivation showed its maximum yield in loam soil when the pF values were maintained from 1,5 to 2.1 and then the evapotranspiration ratio was 1, 76 and also when the amount of irrigation water were similar, it showed effective to reduce the days of intermtission. 6. The result of cucumber cultivation showed its maximum yield in sandy loam soil when the pF value maintained from 1.5 to 1.7 and when the irrigation point maintained at pF 2,7 in sandy soil, its yield was severely decreased.

• Computers and Concrete
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• v.17 no.4
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• pp.489-498
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• 2016

In this paper, the flexural strength ($f_{fs}$) and splitting tensile strength ($f_{sts}$) of concrete containing different proportions of fly ash have been modeled by using gene expression programming (GEP). Two GEP models called GEP-I and GEP-II are constituted to predict the $f_{fs}$ and $f_{sts}$ values, respectively. In these models, the age of specimen, cement, water, sand, aggregate, superplasticizer and fly ash are used as independent input parameters. GEP-I model is constructed by 292 experimental data and trisected into 170, 86 and 36 data for training, testing and validating sets, respectively. Similarly, GEP-II model is constructed by 278 experimental data and trisected into 142, 70 and 66 data for training, testing and validating sets, respectively. The experimental data used in the validating set of these models are independent from the training and testing sets. The results of the statistical parameters obtained from the models indicate that the proposed empirical models have good prediction and generalization capability.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.3
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• pp.337-342
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• 2004

Previous experiment was performed under abiotic condition. Steady-state abiotic experiments in the sand-tank reactor with air flowing through the reactor headspace demonstrated that oxygen supply through the water table interface into the saturated zone was enhanced when an LNAPL (dodecane) pool was present at the water table. Biotic condition was considered in this study. Biotic experiments performed after inoculating the reactor with Pseudomonas putida mt-2, which does not grow on dodecane, indicated that the enhanced oxygen supply in the presence of the LNAPL pool also enhanced biodegradation of a solute (glucose) plume passing beneath the LNAPL pool at steady-state.

• Water for future
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• v.20 no.1
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• pp.49-54
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• 1987

A numerical analysis of the characteristics of wave reflection over rippled beds (sand bars) was carried out By Boundary Element Method(B.E.M) using linear elements. It is assumed that the incident wave is normal and oblique to the rippled beds and the wave may be and the escribed by two-dimensional linear theory. The accuracy of the computational scheme is investigated by comparing the laboratory data, the analytic measured results of the other researchers. The B.E.M results for the normal incident wave is held for the mechanism of the resonant Bragg reflection at the point where the wave length of the bottom undulation is one half the wave length of the surface wave.