• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.291-296
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• 1998

In the present study, the high strength concrete which is adequate for the long span PC beam above 40 meters has been developed. The optimum cement for high strength concerete was selected through laboratory tests and in-situ mock-up applications. The optical concrete mix design was performed, and the properties of fresh concrete and hardened concrete have been investigated. These results of laboratory study are analized and compared to domestic and foregn design codes and specifications. Finally, the developed high strength concrete was applied to half-scale PSC beams and showed good applicability in field conditions. It is conclude that hte developed high strength concrete can be applied to civil and architectural structures in the field applications.

• Geotechnical Engineering
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• v.8 no.3
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• pp.23-36
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• 1992

The flat dilatometer(DMT) has been practically used as an in-situ test equipment. It is a simple, rapid and cost-effective tool to characterize the in-situ stress-strain-strength properties of various types of ground materials. However, the results of flat DMT should be validated with considerable data with respect to the known reference values for a specific site. In this study, the applicability of existing relationships which were established for other local deposits is verified by performing the tests in several clay deposits. To compare with the DMT results, field vane tests and cone penetration tests were also carried out in the same field as reference tests, and unconsolidated undrained tests, oedometer tests, and other fundamental material properties tests were conducted on the thin-walled tube samples in the laboratory. The results of the flat DMT combined with empirical correlations are used to estimate soil types, unit weights, coefficients of lateral earth pressure at rest, overconsolidation ratios, constrained moduli and undrained shear strengths of three clay local deposits. It was found that various geotechnical properties estimated from the flat DMT generally well agree with those from the reference tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.5 s.57
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• pp.121-132
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• 2009

This paper introduces an experimental verification and a field application of the proposed technique using the combination of FEM and HGA about the loss prestressing force of an exteranl tendon by above same authors. The vibration tests have been conducted by using a laboratory models and the externally prestressed tendon at the field and the natural frequencies are extracted from the vibration tests. The proposed technique based on the extracted natural frequencies is applied. It is seen that the errors in the tension and lost prestressing force by proposed technique are about 4% from a laboratory model test. For the model verification at field, exact modeling has beem made with Rayleigh damping. It is seen that the error in the tension by proposed technique is less than 1% and the estimated lost prestressing force converges less than the exact value.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.117-122
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• 1999

Laboratory and field investigations of the coefficient of vertical and horizontal consolidation for Yangsan clay deposit were carried out using the conventional oedometer, Rowecell and piezocone test. Correlation among these test methods were also studied. In this paper, the relationship between vertical and horizontal consolidation were suggested such as C$\sub$h(Oed)/=0.75∼1.46 C$\sub$v(Oed)/, C$\sub$h(Rowecell) =1.95∼2.93 C$\sub$v(Oed)/, C$\sub$h(piezocone)/ =1.0∼5.0 C$\sub$v(Oed)/. As a result, a fair approximate estimations of C$\sub$h/ can be made by simple test using the conventional oedometer tests.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.117-127
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• 2004

A risk analysis on the cutting slope of roads near Cheongju area was carried out with the data from geological map, field investigation, and laboratory test and with the Geographic Information System. A risk analysis method on the cutting slope of road using the Geographic Information System was developed with the data from geological map, field investigation and laboratory tests. In the GIS, road factors which are safety factor, class of road, slake index, slope-protection works, and height of slope in the cutting slopes are classified into some ranks, and their weighting factors were taken into account. This method can be applied effectively to a road management.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1053-1062
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• 1993

The effect of loading speed on soil failure was studied by using a high speed triaxial compression test. Tests were conducted at 0.35-6.2m/s loading speed to compress soil specimens of sandy loam at different moisture contents. The axial stress at fracture increased with increase in loading speed up to certain critical speeds, however they decreased as the speed up to certain critical speeds, however they decreased as the speed increased further. Experiments were also conducted in the field of sandy loam soil with the vibrating tillage tool. Tests were done at 0.33-0.85m/s tractor speed oscillating frequency 13.7hz and oscillating amplitude 59mm. The maximum oscillating velocity of tillage tool was 2.5m/s. It was observed that for the oscillating operation, initially draft slightly increased with increase in forward speed and then it decreased .For the non-oscillating operation, draft increased continuously with increase in forward speed. Approach of studying soil failure in the laboratory test can be related to the field experiments.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.44-52
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• 2002

The mechanism of pullout resistance of compression anchor is analysed. This anchor is developed through the field pullout tests and the laboratory element test. The compression anchor is characterized by decrease of progressive failure, simple site work, economy and durability compared with tension anchor. The characteristics of compression anchor, compared with tension anchor. mainly are summarized as follows ; (1) The plastic displacement of anchor body is very small during pullout of anchor. (2) Total anchor length decreases by the shortening of free length; (3) The progressive failure is decreased.; (4) The safety factor for pullout resistance increases with time after construction of anchor.

• Journal of the Korean GEO-environmental Society
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• v.2 no.1
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• pp.91-101
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• 2001

This paper investigates the effectiveness of quick lime piles for soft ground improvement. The field tests based on the results of the laboratory test were performed, and the results of field tests were compared with those of numerical analyses(FEM). The results of the field test showed that the domestic quick lime was very effective in reducing the water contents of the surrounding ground quickly due to its characteristics such as digestion, absorption, and exothermic reactions. Accordingly, consolidation occurred without any additional load increment and the shear strength of surrounding ground was increased more than twice. Therefore the quick lime pile method could be considered as an excellent improvement technique reducing the improvement period for soft ground. For the practical applications of the quick lime pile method, issues such as hydration heat, particulation and equipment enhancement should be solved through continuous research and development.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.23-33
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• 2012

The current paper deals with a new live-line insulator inspection tool system that will be used by the Korea Electric Power Corporation for its 154 kV power transmission lines in 2011. Unlike the existing contact type tools, the developed inspection tool automates parts of the insulator inspection process using a sensor and an actuator. The tool sustains its weight independently, not by a lineman. In addition, the inspection tool measures the insulation resistance of an insulator together with its distribution voltage, thus providing more information for analysis and diagnosis. Such characteristics improve the system's operation efficiency, measurement reliability, and usability. We confirmed its effectiveness through live-line field tests with actual power transmission lines.

• Advances in Traditional Medicine
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• v.6 no.1
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• pp.21-26
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• 2006

The ethanolic extract of Fleurya interrupta Gaud, (Urticaceae) was tested for its possible neuropharmacological effects on experimental animals, For the primary neuropharmacological screening of this plant, the ethanolic extract of its aerial parts was subjected to preliminary evaluation for acute toxicity, antinociceptive activity and central nervous system (CNS) activities. At the doses of 125 and 250 mg/kg, the extract significantly (P < 0.01 and P < 0. 001) and dose-dependently increased the frequency of acetic acid induced writhing in mice. In the pentobarbitone induced sleeping time test, the extract at the above dose levels, significantly and dose-dependently decreased the pentobarbitone induced sleeping time (P < 0.001) and increased the time for onset of sleep (P < 0.001) in mice. In the open field and hole cross tests, test animals showed an increase in their movement in the both tests from the 2nd observation period (30 min) and persisted throughout the entire experimental period (240 min). These results of the extract may attribute a stimulating action on the CNS. On the basis of these findings, it can be assumed that the extract exerts its stimulating effect on the CNS in mice by interfering with the cortical function or increasing the effect of some CNS stimulating neurotransmitters.