• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.695-702
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• 2002

Shotcrete (or Sprayed concrete) has been used as an important support material in New Austrian Tunnelling Method (NATM). Since the mid of 1990, permanent shotcrete tunnel linings such as Single-shell, NMT (Norwegian Method of Tunnelling) has been constructed in many countries for reducing the construction time and lowing construction costs instead of conventional in-situ concrete linings. Among essential technologies for successful application of permanent shotcrcte linings, high performance shotcrete providing high strength, high durability, better pumpability has to be developed in advance as an integral component. This paper presents the Ideas and first experimental attempts to increase early strength and bond strength of wet-mixed Steel Fiber Reinforced Shotcrete(SFRS) in sump water condition. In order to increase early strength, a new approach using high-early strength cement with liquid alkali-free accelerator has been investigated From the results, wet-mix SFRS with high-early strength cement and alkali-free accelerator exhibited excellent early strength improvement compared to the ordinary portland content and good bond strength even under sump water condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.269-281
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• 2010

The cone penetration test(CPT) has been increasingly used for in situ site characterization. However, the use of CPT is often limited due to specific site conditions depending on the cone size, geometry, and capacity of the CPT system used. In South Korea, it has generally been considered that the CPT could be satisfactorily performed only in soft soils. Louisiana State University/ Louisiana Transportation Research Center has implemented a field-rugged continuous intrusion miniature cone penetration test (CIMCPT) system since the 1990s. The miniature cone penetrometer of the CIMCPT system has a cross-sectional cone area of $2cm^2$ allowing finer soil profiles compared to the standard $10cm^2$. The reduced cross-sectional area also enables a system capacity reduction leading to cost saving and ease in maintenance. In addition, the continuous intrusion mechanism allows fast and economic site investigations. Samsung C&T Corporation has recently implemented a similar CIMCPT system. In this study, case studies on the field application of Samsung CIMCPT system for the last 2 years are presented to illustrate its performance investigation and its usefulness and limitation. Results of the case studies show that the CIMCPT system can be applied to soils with cone tip resistance($q_c$) values up to about 30MPa and allows a reliable and useful way to characterize soft soils. The results also show that the rod buckling limits the investigation depth by the system and the large contact pressure of the CIMCPT truck prevents the use of the system at sites with soft surface soils. According to the results of the case studies, the Samsung CIMCPT system has been being upgraded with a miniature cone with a longer rod, a crawler-type transportation system, a pre-boring system, and so on.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.1-8
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• 2005

As a trial to find an efficient technique for determining hydraulic conductivity, a test application of electrical conductivity measurement technique was made using a signal conditioning data acquisition system in borehole. The experiment was made in two test boreholes BM-2 and BM-3 which are located in the Experiment forests of Kangwon National University in Bongmyongri, Chunchon. We obtained series of electric conductivity variation curves after the beginning and completion of saline water injection using these two bore-holes as the pumping well and the observing well alternatively, The analysis of time series electrical conductivity data suggests kinds of valuable information about aquifer properties by holes and depths, and we could confirm the potential of this method as an efficient tool for in situ aquifer test.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.100-111
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• 2006

This study was carried out to increase the efficiency of site investigation through the evaluation of the applicable methods of investigation for cutting slope design. In an effort to find out the applicability of the method employed during the slope investigation, some tests were carried out on 6 subjects i.e location of weak zones, characteristics of discontinuities, distribution of strata, in situ tests for geo-technical properties, laboratory test and estimation of weathering. The method was highly applicable and produced expected results during the test of weak zones, discontinuities and distribution of strata. In order to apply the method to in- situ test for geo-technical properties and laboratory test on soil and rock slope, a statistic analysis of the existing data were required in advance. However its design applicability on rock slope was good although actual cases of application were not many due to limitation of the cases for investigation. The method was frequently referenced but not actually applied for anti seismic design test and estimation of weathering.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.421-424
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• 2006

Nafion/Pt/Polypyrrole composite membranes were fabricated by chemical in-situ polymerization of pyrrole monomers with Pt precursors in Nafion matrix for DMFC. We demonstrated that positively charged pyrrolinum groups of polypyrrole particles were co-interacted with sulfonic groups of Nafion as verified by FT-IR results. Mutual interaction between $Nafion-SO_3^-$ (or negatively charged Pt precursors) and Polypyrrole$-NH_2^+$ influenced the physical properties of pristine Nafion. Thermal property proton conductivity, methanol permeability, and cell performance of pristine and modified Nafion were analyzed for an application of DMFC membrane. Thermal stabilities of sulfonic groups and side chains in Nafion/Pt/polypyrrole composite membranes were higher than those of Nafion due to mutual interaction between sulfonic groups of Nafion and pyrrolinum groups of polypyrrole. Methanol permeabilities of Nafion/Pt/Polypyrrole composite were reduced more proton conductivities with the increase in the content of Pt particles. As a result of that, the enhancement of cell performance by Nafion/Pt/Polypyrole O2 relative to Nafion was more pronounced under the specific experimental condition such as high temperature and more concentrated methanol solution.

• Polymer(Korea)
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• v.29 no.4
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• pp.321-330
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• 2005

In 1990's the Korean polyolefin industry boomed up through the development of magnificient polymerization catalysts. To understand the general situation of polymerization catalyst R & D, the various experimental results had been summarized for the investigation of not only the supported Ziegler-Natta catalyst used presently in polyolefin industry but also the metallocene catalysts applied for the preparation of special grade of polyolefin. In addition, it had been shown that the new polymeric materials were prepared by new developed catalyst, and the polymer in-situ nanocomposites could be obtained with the application of catalyst heterogenization procedures.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.117-121
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• 2005

In order to monitor the levels and seasonal variations of EDCs, samples of the discharged effluent from sewage & wastewater treatment plants and river waters were collected. The target EDCs including bisphenol A and alkylphenols were determined by Laser-induced fluorescence(LIF) as in-situ monitoring technique. The category of EDCs showed similar fluorescence spectra and nearly equal decay time. This point makes it hard to distinguish each EBCs from the EDCs mixture by LIF and LIF results were expressed only by the total EDCs. However, LIF monitoring results and GC-MS results was comparable. The correlation coefficient between EDCs concentration acquired from GC-MS and fluorescence intensity from LIF was significant. This study supports the feasibility of the application of LIF into EDCs monitoring In aquatic system.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.309-310
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• 2006

Porous titanium implants can be produced by powder metallurgy in combination with suitable space holder materials. Various mechanical experiments were done to characterize this material regarding the influence of the processing parameters on microstructure and mechanical properties taking into account the properties of the human bone. In this paper, the anistropic behaviour of uniaxially compacted samples was analysed in compression tests and compared to the behaviour of isostatically pressed samples. The failure of the struts of the porous titanium and the crack- initiation and -growth was examined by in-situ SEM analysis.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.191-198
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• 2018

Improper management and unsanitary approaches are implemented in disposal of leachate, which has resulted in groundwater pollution at village Uruli Devachi, Pune, India. Various physico-chemical treatment methods are commercially available for leachate treatment. However, the application of biological methods viz. phytoremediation to the municipal solid waste landfill leachate has been limited. We report the remediation ability of Typha aungstifolia and Acrorus calamus that is capable of reducing hazardous constituents from the landfill leachate. After 96 h of hydraulic retention time (HRT), it was observed that T. aungstifolia-treated sample showed high reduction potential in reducing biochemical oxygen demand, chemical oxygen demand, hardness, total dissolved solids, Na, Mg, Ca and Ni whereas A. calamus showed greater reduction capacity for alkalinity, Cl, Cu, Zn and Cr. Furthermore, it was also observed that T. aungstifolia withstood longer HRT than A. calamus. In situ application of T. aungstifolia and A. calamus for remediation of landfill leachate carries a tremendous potential that needs to be further explored.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.223-230
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• 2004

It is growing the application of the removal ground anchor with tension force for earth retaining constructions in the downtown. Nowadays, we can find the compression dispersion anchor on many site. But, it is occur some probelems in behabior of anchors because of impossible to tense p.c strand uniformly with existing equipment due to different length of p.c strand. So we tried to tense each p.c strand uniformly with auto back equipment in-situ test. This study compared and analyzed apply to elastic theory in-situ test results of an existing equipment with those of auto back equipment. As a result of the test, It has been proved that differences of tension force in the existing equipment increases with increasing the number of p.c strand. This can cause an ultimate failure of the concentrated p.c strand and a shear failure of ground. So it has been proved that auto back equipment is necessary.