• 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 the Korean Society of Clothing and Textiles
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• v.46 no.1
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• pp.49-62
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• 2022

The embroidered Kasaya is the twenty-five column Kasaya of Triratna: Buddha, Dharma, and Sangha. Even though it is a representative artifact of embroidery, the method of manufacturing heavily depends on the collector's reports. This study focuses on the prayer's recorder: Gonmyeong Park, born in Muja, and Ven. Haebung, who acted as a historical investigator of embroidered Kasaya. The beginning of Haebung's public record was in 1815, and his entrance into nirvana in 1826. The birth year of prayer in Muja was 1768. Therefore, the embroidered Kasaya was manufactured at the end of the 18th century or the early 19th century. Haebung appears to have played a critical role in historical investigation, and consequently the 125 icons of Triratna are almost identical in three treasures: the Kasaya at Seonamsa Temple, the embroidered Kasaya, and the painting of the embroidered Kasaya at Cheongnyongsa Temple. The embroidered Kasaya was particularly affected by the religion of a thousand Buddhas and by Triratna in the late Joseon era. Unlike the Kasaya of a thousand Buddhas in the Ming and Qing Dynasties, the embroidered Kasaya shows the Triratna in detail, suggesting that the icons of Triratna were newly created.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.5-14
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• 2010

The slope stability method using the soil stabilizer is a way to ensure that the slope stability from reinforcing method is environmentally friendly. However, the reinforcing method does not ensure slope stability for lack of research on the reinforcement effect of the mixture with soil. So the application of this method implies difficult technical issues. In this research, reinforcement effect is investigated according to the different ratio of mixture. And the optimum reinforcement depth is proposed according to the height of slope from numerical analysis. The results show that approximately the soil strength increases from two to three times. From numerical analysis, it is possible to estimate the optimum height according to the height of slope. It is anticipated that the use of soil stabilizer will increase the slope stability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.23-35
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• 2009

This study was performed to investigate the bending stresses of tunnel shotcrete as a function of the coefficient of lateral earth pressure. To perform this study, a large scale model tunnel with an one-lane horseshoe shaped road tunnel was prepared. The 3 dimensional numerical analyses were carried out to verify the results obtained from the model tests. For the loading system during the tests, 11 cylinder pressure jacks which can be controlled individually were used to simulate various loading conditions. The tests were preformed three times with three different lateral earth pressure coefficients of 0.5, 1.0 and 2.0. The bending stresses of shotcrete measured in tests were compared and analyzed with those calculated from numerical analyses. As a result, it was found that the bending compressive stresses obtained from numerical analyses were similar to those of tunnel model tests and bending tensile stresses were slightly overestimated during numerical analyses.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.2
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• pp.117-127
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• 2010

Gound excavation is frequently executed in unsaturated soil conditions. In this paper, the effect of apparent cohesion in unsaturated soils on the ground behavior during underground excavation is studied. The VPPE (Volumetric Pressure Plate Extractor) test, the unsaturated triaxial test and the trap-door test were carried out to figure out how the behavior of soils varies depending on the variation of apparent cohesion. The test results show that the ground behavior is almost identical if the soil is either fully dry or fully saturated. However, if the soil is partially-saturated with the increase of water content, the ground behaves quite differently. In summary, the apparent cohesion in unsaturated soils plays key roles when excavating underground structures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.189-198
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• 2009

Recently the concern about the construction of underground structures such as oil and food storage caverns is increasing in Korea and abroad. The stability of those underground caverns is greatly influenced by shape factor and the size of excavation area as well as the joint conditions. In this study, therefore, the effect of the shape factor of an underground cavern on its stability was analyzed in terms of safety factor. To this end, four different shape factors of a cavern excavated in good rock conditions were investigated and sensitivity analyses were performed based on overburden, lateral earth pressure coefficient, joint spacing, properties, and orientation. The stability of a cavern is evaluated in terms of safety factor estimated numerically based on the shear strength reduction technique. In future, this study is expected to be helpful in designing and evaluating the stability of caverns excavated in discontinuous rock masses.

• Journal of the Korean earth science society
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• v.37 no.4
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• pp.211-217
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• 2016

There have been found mine tailings, wastes, and mining drainage scattered in the area of Nakdong River due to the improper maintenance of the abandoned mines. These contaminants can flow into rivers during the heavy rain periods in summer. Along the study area beginning Seokpo-myeon, Bonghwa-gun of Gyeongsangbuk-do untill Dosan-myeon, Andong-si, there are one hundred five mines including sixty metalliferous mines and forty-five nonmetal mines, which can adversely affect the adjacent rivers. To verify the contamination, we collected sediments, seepage water and surface water for a year both in rainy season and dry season. This study found that sediments, containing high concentrations of heavy metals caused by mining activities, are dispersed throughout the entire river basin (68 sample points with pollution index, based on the concentration of trace element, (PI) >10 among the total of 101 samples). The results of river water analysis indicated the increased concentrations of arsenic and cadmium at branches from Seungbu, Sambo, Okbang and Janggun mine, which concerns that the river water may be contaminated by mining drainage and tailing sediments. However, it is difficult to sort out the exact sources of contamination in sediments and waters only by using the chemical compositions. Thus the control of mining pollution is challenging. To prevent water from being contaminated by mining activities, we should be able to divide inflow rates from each origin of the mines. Therefore, there should be a continued study about how to trace the source of contaminants from mining activities by analyzing stable isotopes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.699-714
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• 2022

The objective of this study is to suggest a safe and economical pillar reinforcement method when very near-twin tunnels with a minimum interval of 1 m passes through a soft zone such as weathered soil or weathered rock. A standard cross-sectional view of a two-lane road tunnel was applied to suggest a pillar reinforcement method for the very near-twin tunnels. The thickness of the pillar was 1 m. The ground condition around the tunnel was weathered soil or weathered rock. There were four reinforcement methods for pillar stability evaluation. These were rock bolt reinforcement, pre-stressed steel strand reinforcement, horizontal steel pipe grouting reinforcement, horizontal steel pipe grouting + prestressed steel strand reinforcement. When the ground condition was weathered soil, only the pillar reinforced the horizontal steel pipe grouting + prestressed steel strand did not failed. When the ground condition was weathered rock, there were no failure of the pillar reinforced the horizontal steel pipe grouting or the horizontal steel pipe grouting + prestressed steel strand. It is considered that the horizontal steel pipe grouting reinforcement played a role in increasing the stability of the upper part of the pillar by supporting the upper load applied to the upper part of the pillar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.60-66
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• 2019

Many researches have been performed on hybrid fiber reinforced concrete for years, which is to improve some of the weak material properties of concrete. Researches on characteristics of hybrid fiber reinforced concrete using amorphous steel fiber and organic fiber, however, yet remain to be done. Therefore, the purpose of this research is to estimate the compressive strength, long term drying shrinkage, and resistance to freezing and thawing of hybrid fiber reinforced concrete(HFRC) using amorphous steel fiber and polyamide fiber as one of organic fibers. For this purpose, HFRCs containing amorphous steel fiber and polyamide fiber were made according to their total volume fraction of 1.0% for target compressive strength of 40 and 60 MPa, respectively, and then the compressive strength, length change, and resistance to freezing and thawing of these were evaluated. As a result, the long term length change ratio of HFRC used in this study decreased by more than 30%, 25% than plain concrete at 365 and 730 days, respectively, and the durability factor of HFRC was very excellent as more than 90%.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.189-199
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• 2019

In this study, behaviors of fire smoke in the operation of disaster prevention facilities (smoke damper, jet fan) in a tunnel-type structure (soundproof tunnel) were investigated numerically and results of the investigation were compared and analyzed. Through the simulation and analysis, it was found that there was a significant change in the patterns of fire smoke between the opening of the ceiling of a fire vehicle and the closing, and it was shown that the critical temperatures of PC and PMMA, main materials of a soundproof tunnel were not exceeded. In addition, the simulation of installation intervals of smoke dampers showed that the maximum temperature of a soundproof tunnel without smoke dampers was $552^{\circ}C$ while it reached $405^{\circ}C$ when smoke dampers were installed at the installation interval of 50 m. The simulation of the operation of a jet fan showed that the maximum temperature of a soundproof tunnel without a jet fan was $549^{\circ}C$ while it reached only $86^{\circ}C$ when a jet fan was operating. Therefore, it is highly expected that they could create a favorable environment for evacuation and protection of soundproofing materials, and it would be necessary to promote basic studies on tunnels serving various functions and purposes.