• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.359-364
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• 2012

In order to prevent the decrease in well efficiencies due to friction in the axial flow in long, large-diameter laterals, a multi-diameter lateral was devised and tested through lab-scale sand-box experiments to assess its performance. In the experiment, three different production rates were applied over the multi-diameter and the three single-diameter laterals to obtain the hydraulic head distributions for each, which was used to assess the performance of the laterals. Results elucidated that the multi-diameter lateral reduced the material cost by more than a third, in comparison to the single-diameter lateral, while maintaining the production rate at higher than 93%, proving its superiority. Furthermore, results indicated that exit velocities exceeding 0.8 m/sec in horizontal wells tended to distort the hydraulic head distribution near the exit, providing evidence of its inefficiency.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.334-339
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• 2013

A pilot-scale sand-box experiment simulating a lateral of collector well used in riverbank filtration was performed, and hydraulic head distributions along the lateral were measured according to the various drawdowns at the well. The results of this experiment were compared to the predicted values obtained using a theory previously developed by Kim in order for its validation. This theory predicts the head loss in a large-scale lateral given the loss in a small-scale one, and to have actual values for comparison, the results from a lab-scale experiment previously performed by Kim were employed. Comparing the experimental values to the extrapolated value indeed confirmed the validity of the theory. A procedure to determine the hydraulic head distribution of a practical-scale lateral was also presented applying the theory to the experimental result of this study in an effort to show the process of lateral design for riverbank filtration.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.91-99
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• 2012

This study describes the investigation based on centrifuge model tests for the clay ground improved by sand compaction pile. In order to clarify the failure behavior of composite ground improved by partly and fully penetrated SCPs. And, in order to compare the effect of the penetration ratio and the replacement area ratio, nine of the centrifuge tests were carried out. From the test results, settlement reduce ratio in the fully penetrated SCPs ground is bigger than that in the partly penetrated SCPs ground. It is also evaluated that angle of the failure of composite ground improved by SCP are 26, 25, $34^{\circ}$ for As=10%, 22, $29^{\circ}$ for As=30%. And as a result of rigid loading tests, surface displacement decreases linearly with the partly penetration ratio increased.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1305-1310
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• 2005

As a way to the optimum design of the collector well lateral in riverbed filtration, experiments were performed using sand tanks which were connected to form a model lateral system. Measured were the residual hydraulic heads along the laterals, the discharge rates at each sand tank and the production rates at the collector well while the model laterals were operated with various scenarios of changing parameters including water level of the collector well, the lateral diameter and length, and the hydraulic conductivity of the sand. Results showed that riverbed filtration could be more efficient when the resistance in the lateral was weak compared with the resistance in the sand, which was indicated by the more flattened distribution of the residual hydraulic heads along the lateral. Results also showed that the discharge rate increased exponentially with the approach to the collector well, and that the exponent increased as the lateral diameter decreased and/or the hydraulic conductivity of the sand increased. It was also seen that the well production increased with the increase in the lateral length and diameter although the marginal productivity decreased. It could be concluded that the axial flow velocity in the lateral was an important factor governing the efficiency of a lateral in riverbed filtration and that the maximum entrance velocity to the collector well, over which the efficiency decreased drastically, was about 1 m/sec under the conditions of this study.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.430-437
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• 2012

In order to obtain information on the design parameters of the horizontal laterals in floodplain filtration, laboratory-scale sand-box experiments were performed where the head distributions on the laterals and the groundwater profiles were measured according to the change in parameters including lateral diameter, hydraulic conductivity of the sand, water level at the well and raw-water supply rate. Measured data were analyzed using a numerical code in order to identify the discharge intensity distribution along the laterals. It was observed from the result that the lowering of the water level at the well had minimal adverse effect on the performance of the floodplain filtration. Results also elucidated that the low conveyance of the laterals to transmit the filtrate was compensated and supplemented by a natural augmentation in horizontal conveyance through the aquifer when the raw-water supply rate exceeded the adequate recovery rate. With this mechanism, the water quality is expected to improve further since the travel distance through the aquifer is amplified. Based on these findings it can be suggested that the diameter of the lateral used in the floodplain filtration may be smaller than those in riverbank/bed filtration. It was also found that the ratio between the head loss occurring in a lateral and the total head loss in the floodplain filtration was proportional to the exit velocities of the laterals, which may be used to design and/or evaluate the lateral in floodplain filtration.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06a
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• pp.18-24
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• 1995

본 연구에서는 두가지 엔진에 사용된 엔진오일의 성상변화를 측정하였다. 따라서 금속 마모입자 분석, 동점도 측정과 TAN 및 TBN 분석을 통한 물리적 성상과 화학적 성질 분석 그리고 적외선 분광 분석과 정량 폐로그라피 분석 등을 통하여 Table 1에 나타난 기준에 의해 오일의 수명을 판정하였다. 아울러 RPD를 이용하여 마모입자의 형상 등을 분석하고 엔진에서 발생하는 마모기구를 살펴보았다. 물론 본 연구는 주위 환경이 양호한 실험실에서 엔진 동력계에 의한 실험에 의존하였으므로 실제 주행실험 결과보다는 오일의 수명이 더 길게 나타날 것으로 예측된다. 더욱이 농경지에서 주로 사용되는 경운기의 경우는 오일이 먼지나 모래, 진흙 등에 의해 오손되기 쉬우므로 실제 오일의 수명은 훨씬 더 짧을 것으로 생각되므로 실차 주행실험 결과와의 비료는 앞으로 더 연구할 분야로 생각된다.

• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.57-63
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• 2007

Coal combustion by-product (CCB) bottom ash, obtained from burning of pulverized coal, has physical properties which are similar to that of natural sand with particle sizes ranging from fine gravel to fine sand. Several studies have been completed to utilize pulverized coal combustion (PCC) bottom ash as a partial or full replacement of fine aggregate in cement concrete products. The objectives of this study were to develop air-entrained concrete composites using PCC bottom ash from burning of Illinois coal and to demonstrate the use of these composites on real-world projects. The results obtained show that the compressive, splitting-tensile, and flexural strengths of concrete composites is slightly lower than that of conventional concrete are early curing ages. However, after 60 days of curing, the strength of concrete composites is either equal to or slightly higher than that of an equivalent conventional concrete. The concrete composites showed lower resistance to chloride ion penetrability than that of an equivalent conventional concrete at early curing ages. However, after 28 days of curing, concrete composites showed better resistance to chloride ion penetrability compared to that of an equivalent conventional concrete.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.957-964
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• 2009

Sand tank experiments were performed along with on-site supplier experiments in order to obtain design factors for the raw-water supply system in floodplain filtration. Results of the sand tank experiment elucidated that the infiltration rate was approximately proportional to the soil permeability and was not significantly influenced by short periods of rest. The average daily infiltration rate calculated by taking both flood and rest periods into account increased with increasing flood period, and was observed to reach an asymptote. Under the conditions of this study, the maximum infiltration rates obtained for both Daegu and Mulgeum soils with 15 min/ 30 min of rest/flood periods were 6.3 m/day and 1.4 m/day respectively, which were 42% and 70% of their hydraulic conductivities, respectively. The process of soil filtration resulted in a gradual decrease of hydraulic conductivity; a decrease of 27% was observed for the soil of Mulgeum over a period of 8 days. From the data obtained from the supplier experiment, it was evident that the radius of the flooded area increased as the supply rate increased for soils of Gumi and Sangju, however, there was an inverse correlation between hydraulic conductivity and the rate of increase in the radius. Results also showed that the time required to cover the entire soil surface with water, in other words, the time to reach the maximum flood radius from the commencement of the water emission was as short as 3 to 4 minutes for all the soils. Also, the average infiltration rate for the entire flood period did not change significantly when the rest period was shorter than an hour.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.15-22
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• 1985

The author has studied the collapse of a slope with seepage occuring in sand model with a trapezodial cross section. The primary objective of this study was to examine the failure phenomenon of embankment with respect to change in void pressure at embankment slope. The contents of this experiments are as follows; 1) Determination of exit point by seepage line. 2) Evaluation of partial failure at exit point. 3) The effects of seepage force at embankment.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.132-138
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• 2009

Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for making PTF(Pedo-Transfer Function) for Kfs(field saturaton hydraulic conductivity) estimation, and for investigating the relation between soil particle distribution and the infiltration and percolation rate in soils originated from limestone. Soils used for the experiment were 6 soils of Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate for the soil were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. The particle size distribution and organic matter content of the soils were analyzed. Kfs was not related with sand, silt, clay, and organic mattrer (OM) content because of forest soils which contained high gravel, pebble, and cobble content, and O layer with high OM content. After Mosan soil series and O layer of Gwarim series were excluded for the data analysis, Kfs was explained as a linear function with sand and clay content and a exponential function with OM content. As a result, the PTF equation was obtained as Kfs=-4.20558+0.479706*(S)+0.023187*exp(1.829*OM) ($R^2=0.6558^{*}$).