• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.910-920
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• 2008

In Korea, more than 70% of the territory consists of mountains. Therefore, the construction of roads and railways has generally involved with a steep rock slope in which the event of rockfalls are often occurred due to the weathered rock conditions and rainfalls etc. This is dangerous when the rock falls into the road and railway on which vehicles and trains are running. In order to prevent such rockfalls, the rockfall protection fence consisting of post, wire rope, and PVC coating steel net has most used at the bottom of rock slopes. In a general practice, an absorbing rockfall energy, 50kJ is specified by the Ministry of Construction and Transportation. However, questions still remain about whether the rockfall protection fence works effectively or not. In this study, a typical wire rope used in the standard rockfall protection fence was replaced by the high carbon steel wire rod and to validate its capacity of rockfall energy absorbing the field rockfall tests were conducted. The testing results show that a new rockfall protection fence using the high carbon steel wire rods can absorb the rockfall energy more than 50kJ and 20% of construction cost was saved in comparison with the previous rockfall protection fence.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.49-60
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• 2009

In order to develop a new rockfall protection fence using high carbon steel wire rod (HSWR) material instead of the conventional wire rope material, the author has conducted the laboratory strength tests of both materials and their connections, and carried out evaluation of absorbing rockfall energy through the vertical field rockfall tests. The vertical filed rockfall tests showed that the new rockfall protection fence with 12 rows of the HSWR could absorb more rockfall energy than 50 kJ which stands for the typical design criteria. In addition, when the quantity of HSWR was increased up to the 16 rows, the capacity of absorbing energy was greatly improved. The new rockfall protection fence was successfully applied to the highway rock-cut slope. As a result of the filed application, its constructability was similar to the conventional fence, but its total image was improved as simple and clean. The total construction cost was saved up to 20% in comparison with the conventional one.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.4
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• pp.230-236
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• 2023

The current study deals with the effect of cooling rate and temperature for annealing on medium-carbon Cr-Mo alloy steel, especially for cold heading quality wire rod, to derive the optimum micro-structures for plastic deformation. This is to optimize the spheroidization heat treatment conditions for softening the material. Heat treatment was performed under seven different conditions at a temperature between A_c1 and A_c3, mostly within 720℃ to 760℃, and the main variables at this time were temperature, retention time and cooling rate. Microstructure and phase changes were observed for each test condition, and it was confirmed that they were greatly affected by the cooling rate. It was also confirmed that the cooling rate was changed in the range of 0.1℃/min to 5℃/min and affected by phase deformation and spheroidization fraction. The larger the spheroidization fraction, the lower the hardness, which is associated with the increasing connection of ferrite phases.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.677-682
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• 2012

For the product with small diameter, long column, and parabolic shape, the forging formability of the high-carbon steel wire rod was investigated in this study. By using the three-dimensional finite element method, the formability of wire was reviewed by forming analysis for the desired parabolic shape of local part. Analysis results due to forging direction, forging velocity, friction coefficient and constraint location were also investigated. On the basis of these results, it is noted that the forging direction has the big influence when the product with long column is forged. As the forging velocity increases, buckling tends to be limited and formability of parabolic shape is improved. By constraining the lower parabolic shape part to suppress plastic strain, the effect depending on friction coefficient is not almost appeared. And good parabolic shape is obtained at the region of the forging velocity of more than 0.5 m/s.