• Journal of the Korean Society of Groundwater Environment
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• v.4 no.2
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• pp.61-72
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• 1997

With increasing activities for groundwater withdrawal and for the construction of underground cavern in the coastal areas, the seaward flow of groundwater has been disturbed or even reversed, resulting in seawater intrusion in aquifers. This phenomenon would be attributed to the freshwater contamination and the corrosion of steel materials. The hydrogeological and geochemical investigations have performed to characterize the seawater intrusion into the underground caverns located in the coastal area. Assumimg the inland aquifer as unconfined one, we have found out that the theoretical interface of freshwater-seawater is far different from the pathways identified. In the study site, the main pathways of seawater intrusion into the underground cavern are characterized as the sub-horizontal fractures (zones). The seawater intrusion in granitic terrane would depend mainly on the characteristics of conductive fracture system developed along the coastal area.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.3
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• pp.33-40
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• 2011

This paper presents the prediction and evaluation of landslide using LRA(logistic regression analysis) and ANN (Artificial Neural Network) methods. In order to assess the landslide, we selected Sarabong, Byeoldobong area and Mt. Song-ak in Jeju Island. Five factors which affect the landslide were selected as: slope angle, elevation, porosity, dry density, permeability. So as to predict and evaluate the landslide, firstly the weight value of each factor was analyzed by LRA(logistic regression analysis) and ANN(Artificial Neural Network) methods. Then we got two prediction maps using AcrView software through GIS(Geographic Information System) method. The comparative analysis reveals that the slope angle and porosity play important roles in landslide. Prediction map generated by LRA method is more accurate than ANN method in Jeju. From the prediction map, we found that the most dangerous area is distributed around the road and path.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.669-680
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• 1994

DMA-co-DAMA were synthesized from 2-diethylaminoethyl metacrylate and dodecyl-metacrylate containing long chain hydrocarbon group with hydrophilic and hydrophobic radicals. To facilitate water emulsification,acrylic copolymer was cationized by acetic acid to produce acetated acrylic copolymer. The structures of the synthesized copolymer and acetated copolymers were confirmed by IR, NMR, and molecular weight was measured by GPC, and C. H. N elemental analysis. Acetated acrylic copolymers were perfectly emulsified in water and showed increased emulsion stability. Polymer dispersion for cement modifier(PDCM-PDD) was prepared by blending of the guaternized acrylic copolymer synthesized above sodium silicate sodium gluconate oleic acid and triethanol amine. The result with prepared polymer dispersion of cement modfier was examined, and it was found that excellent waterproffing effect; Water permeability ratio is 0.44 under the water pressure of $100g/cm^2$ and 0.55 under $3kg/cm^2$, and water absorption ratio is 0.36~0.47 and 1.02 compressive strength ratio at mixed ratio of water/PDCM-PDD is 45 times.

• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.53-60
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• 2013

On this study, engineering properties of SGR method and SMI method, which are typical sodium silicate methods, were compared through the laboratory test and durability, strength, waterproof characteristic and environmental effects were compared and analyzed with period and condition of curing on each case. As a result of durability test, volume change of SGR is approximately 23-times greater than SMI and the effects on environment are appeared safe on all method. In case of waterproof characteristic test, permeability coefficient is decreased about 24% on SMI, whereas on SGR permeability coefficient is showed to increase because rapid volume change make wider void. Strength characteristics of SMI are appeared higher about 11-times in case of homogel and 3.9-times in case of sandgel than SGR. Which is because volume change of SMI, caused by leaching, is smaller than SGR.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.75-83
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• 2012

Porosity in concrete has close relationship with durability characteristics. Additionally mixed water can help easy mixing and workability but causes increased porosity, which yields degradation of durability performance. In this paper, cement mortar samples with 0.45 of w/c (water to cement ratio) are prepared and durability performances are evaluated with additional water from 0.45 to 0.60 of w/c. Various durability tests including strength, chloride diffusion, air permeability, saturation, and moisture diffusion are performed. Then they are analyzed with changing porosity. Changing ratios and the patterns of durability performance are quantitatively evaluated considering pore size distribution, total porosity, and additional water content.

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.35-42
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• 2013

Recently, construction of reinforced earth structure using geosynthetics has been increased because it has advantages such as construction efficient, cost effectiveness and appearance aspect against existing gravity or cantilever retaining wall. However due to the climate change in Korea excessive inflow of ground water and surface water from heavy rainfall could affect the stability of reinforced retaining wall seriously. So the discharge capacity of drains should be evaluated by using experimental method in the design of reinforced earth wall. In this study, instead of concrete block used in most of the retaining wall, eco-friendly porous soilbag was used. This paper describes the test method and result of the laboratory testing for determination of discharge capacity utilizing PBDs.

• Geotechnical Engineering
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• v.11 no.2
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• pp.99-106
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• 1995

Although lots of experimental studies of coal ash have been performed to study the utilization as construction materials, the environmental characteristics of coal ash are still qestionable. In this study, fly ash is examined to be classified according to Korean Environmental Standard and analized whether the batch test results are within the toler trance limit when utilized or treated as reclamation and earth work materials. The batch tests was performed to examine pH and contaminant contents. Consequently, fly ash is classified as non hazardous industrial waste. The pH value shows a strong alkalinity than the tolerance limit, but it is implied that fly ash can be used to neutralize the acid ground. All other items except pH satisfy the tolerance limit, In addition, a small quantity of additives(cement) which used to improve the poor geotechnical properties of coal ash, could decrease the pH value into the tolerance limit as well as improve strengtIL durability and permeability. It is concluded that when coal ash is used properly, there is no enviormental harmfulness as construction materials.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1630-1637
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• 2008

Jeju-do is a island formed by the volcanic activity and has more than 360 volcanic cones distributed widely along the long axis of the elliptically shaped island. The volcanic cones consist mainly of scoria, so called "Song-I" in the local dialect. In this study the chemical and soil mechanical properties of scoria being very different from those of the inland were investigated with the various tests. In the sieve-passing test the particle size of scoria had more than 10 of uniformity coefficient and gradation coefficient of 1 ~ 3, showing relatively homogenous distribution. Based on the uniformity classification, scoria was assorted into GW. In the large scale direct shear tested for measuring the mechanical strength of scoria the internal friction angle of red scoria was $37^{\circ}$ and that of black scoria was $36^{\circ}$. This indicated that there was no difference in the mechanical strength between two types of scoria. On the other hand, red and black scoria had $1.24{\times}10^{-3}$ to $3.55{\times}10^{-2}$ cm/sec of k values for the static water level permeability, thus being classified into a coarse or fine sand as compared with that representing the saturated soil. They also had 1.411 to $1.477\;g/cm^3$ of notably low $r_{dmax}$ values for the compaction test as compared with common soil, which was considered to be due to their low specific gravity and high porosity. In conclusion, the soil mechanic properties of scoria obtained from this study are thought to be very helpful for reducing lots of trial and error happening in the civil engineering construction.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.332-335
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• 2011

As our interests in eco-friendly materials have been significantly increased, the utilization of porous zeolite concrete that has structural functionality and permeability has been increased. In this paper, the mixture of porous concrete and zeolite, which can be used as multirole boulders, was investigated for the suitability of an environment-friendly product by evaluating of the water purification ability. The contamination removal rates of BOD, TOC, T-N, and T-P in stagnant water tank were 70.6, 67.0, 57.7, and 50.6%, respectively. Also for the non-point source pollution with the inflow and the outflow, the removal rates of Zn, Pb, BOD, and COD were 99.9, 90.0, 69.2, and 33.5%, respectively. The performance of the heavy metal contamination removal for the porous zeolite showed better than that of stagnant system. Therefore, it is expected that the installation of the porous zeolite concrete can play a role as an eco-friendly products by its high contamination removal.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.151-165
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• 2021

Grouting, which is applied for the increase of ground strength and the decrease of permeability, is complex process because of several reasons, so the process needs to be elaborated. Injection process in consideration of ground condition and optimization of grouting sequence is essential. In this study, GIN (Grouting Intensity Number), multiple of injected grout volume and pressure, is revised to consider injection pressure reduction and joint opening during grouting process. A revised GIN process is evaluated through a field test. A revised GIN, considering ground condition, injection pressure, follows GIN envelope and produces rational grouting process. The result of a revised GIN reduces permeability of the ground in the order of 10^-1~10^-2 cm/sec.