• Journal of the Korean GEO-environmental Society
• /
• v.18 no.12
• /
• pp.5-11
• /
• 2017

The 19 mm-sized aggregate was produced by melting vinyl waste (waste polyethylene film) generated from vinyl greenhouses in rural areas. It was mixed with As'cone at various weight ratios, and then insulation effect test, tension test after repeated freezing and thawing, ice pull-out strength test and field density test were conducted for the mixtures. These results demonstrated that as the mixing ratio of polyethylene aggregate increased, the insulation effect increased, due to the many pore spaces that existed in the polyethylene aggregate. After repeatedly freezing and thawing As'cone, the tensile strength significantly increased at 2.5% of the polyethylene aggregate content rather than 0% of polyethylene aggregate content but it also slightly decreased at 5% and 10% of polyethylene aggregate content in comparison to 2.5% of its polyethylene aggregate content. As'cone added with polyethylene aggregate by 2.5% resulted in lower ice pull-out strength than that of normal As'cone. As a result of the porosity test for the samples taken at the site, porosity of the As'cone, which added polyethylene aggregate, was smaller than that of the general As'cone.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1014-1021
• /
• 2008

Ground anchor should not be used in soft clay, because anchor resistance can not be guaranteed. However, there is a way to increase the capacity of anchors. The pulse powered anchor is an underreamed anchor by using high voltage electrokinetic pulse energy. In this paper, conceptual introduction of the pulse powered anchor was presented. Anchor pull-out tests were performed at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. Data were analyzed in order to verify the performance of pulse powered anchors.

• Korean Journal of Applied Biomechanics
• /
• v.14 no.2
• /
• pp.69-83
• /
• 2004

The purpose of this study is searching for technical merits and demerits of each weight lifting player through qualitative motion analysis system. Moreover, It is also analysis the repeating the establishment of exercise purpose and studying for the effect of the field adaptation. The subject of this study was five male weight lifting players who have been engaged in Korean Delegation Team. The institution of exercise target was made through two times qualitative analysis and the result of studying for the effect of the field adaptation was produced before offering feedback. Moreover, two time analysis added after offering feedback. All analysis was based on 2-D visual analysis. The results of this study are as follows: 1. Maximal barbell moving speed in starting phase was decreased after offering feedback. This result implies advancement of technical skills after offering feedback. 2. From starting posture to 앉아받기, forward and backward moving distance of hip joint was decreased after offering feedback in all subjects. This result represents advancement of technical skills after offering feedback. 3. In terms of pull phase, forward and backward moving distance of hip and shoulder joint was decreased after offering feedback in all subjects. This result represents advancement of technical skills after offering feedback. 4. In terms of pull phase, the difference of horizontal value of coordinates was decreased after offering feedback in all subjects. This result represents advancement of technical skills after offering feedback. 5. In terms of pull phase, the motion range of hip joint was decreased after offering feedback in three of five subjects and this represents advancement of technical skills after offering feedback. However, the rest of them were not variable or narrow decreasing. This result represents that feedback system could not brought tremendous effects. 6. From apex point of barbell to 앉아받기, the difference of barbell height was decreased after offering feedback in three of five subjects and this represents advancement of technical skills after offering feedback. However, the rest of them weren't variable or narrow increasing. This result represents that feedback system could not brought tremendous effects. 7. In terms of last-pull phase, the angular velocity of knee joint was increased after offering feedback in four of five subjects and this represents advancement of technical skills after offering feedback. However, the rest of them, only one subject, decreased. This result represents that feedback system could not brought tremendous effects. 8. In terms of last-pull, the conversional tendency of maximal extension to flextion came out all but simultaneously without offering feedback in four of five subjects. This is well-performed technique. Only one subject, however, could not use power effectively because the fact that his maximal extension came out in serial, from ankle to knee and waist means dispersion of power. In addition to, after offering feedback, only one subject made increasing the maximal extension of knee in last-pull and this result represents advancement of skills after offering feedback. However, the rest of them could not make meaningful development after offering feedback. 9. It might be assumed that searching for technical merits and demerits of each weight lifting player through qualitative motion analysis system could improve player's skill.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.6
• /
• pp.31-40
• /
• 2005

In this study, a newly modified soil nailing technology which uses bamboo, rich natural material growing in southern areas, is developed to prevent the soil pollution and to overcome the difficulty of excavation near existing structures. Experimental and analytical studies were performed to confirm application possibility of bamboo taking the place of existent reinforcement material, that is steelbar, FRP and etc. In experimental study, strength characteristics of bamboo material were analyzed, and pull-out resistance of bamboo soil nailing system by field pull-out tests was examined. In analytical study, limit equilibrium analysis and displacement analysis were performed, and application possibility of bamboo soil nailing system was analyzed. As the result of this study, bamboo has comparatively good strength and pull-out resistance characteristics. It is expected that bamboo can be used as satisfactory reinforcement material by selecting bamboo with reguired diameter and by controlling the number of bamboo strips. Bamboo is an alternative for the reinforcement of soil nailing system, especially temporary support system in excavation near the existing structures.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.12
• /
• pp.23-35
• /
• 2023

The Ministry of Agriculture, Food and Rural Affairs has announced design standards for disaster-resilient greenhouses capable of resisting wind speeds with a 30-year frequency to respond to the destruction of greenhouses caused by strong winds. However, many greenhouses are still being maintained or newly installed as conventional standard facilities for the supply type. In these supply-type greenhouses, a small pile called a steel peg is used as reinforcement to resist wind-induced damage. The wind resistance of steel pegs varies depending on the soil environment and installation method. In this study, a correlation analysis was performed between the wind resistance of steel pegs installed in loam and sandy loam, using a soil hardness meter. To estimate the pull-out force of steel pegs based on soil water content and compaction, soil compaction tests and laboratory soil box and field tests were performed. The soil compaction degree was measured using a soil hardness meter that could easily confirm soil compaction. This was used to analyze the correlation between the soil compaction degree in the tests. In addition, a correlation analysis was performed between the pull-out force of steel pegs in the soil box and field. The findings of this study will be useful in predicting the pull-out force of steel pegs based on the method of steel peg installation and environmental changes.

• Journal of Wetlands Research
• /
• v.15 no.4
• /
• pp.431-440
• /
• 2013

It was tested in field that a Pull-out Capacity and Shear resistance strength change of reed, common reed and sedge which were planted by mat-type turf and used for revegetation of bank. The testes were done for 9 weeks from end of May and the grasses were planted on sandy soil. Roots grew fastly after planted and increasement of a common reed and sedge root were reduced after 4 weeks but increasement of reed roots were not reduced. The difference of increasement of roots is due to a difference of propagation method. Sedge propagate by seed. Reed and commom reed propagate by seed and subterranean stem and reed has bigger subterranean stem than common reed. So increasement of common reed and sedge roots were slow than reed. By root growth pattern, increasement of pull-out capacity and shear resistance strength showed very similar way of root growth, those of common reed and sedge were fast in early stage of cultivation but were reduced. But increasement of pull-out capacity and shear resistance strength of reed was not reduced. A Maximum shear resistance strength called critical shear resistance strength of common reed and sedge can be Analyzed at 11 weeks after planted.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.1
• /
• pp.130-137
• /
• 2019

Precast concrete (PC) structure is one of the type of the structures which is made in a facility prior to installing it to a construction field. The contact surfaces between two PC structures should be treated for obtaining enough binding force by inducing prestressing force. However, in the many cases, the contact surface causes the crack and leakage of water. These cracks and water leakage can cause the corrosion of the rebar, and the corrosion of the rebar can severely reduce the long-term durability. In this study, the SMA wire connector is suggested to solve the problem with the contact surfaces between two PC structures. The pull-out resistance of the suggested SMA wire connector is evaluated by conducting the tests to find the effect of the number of wires, shape of connector part, and shape memory effect. As a result of this study, the empirical formula is suggested to estimate the pull-out resistance related with the effects of the shape of the connector, shape memory effect, and the adhesive force. The validity between the estimated pull-out resistance and the measured value is confirmed.

• The Journal of Engineering Geology
• /
• v.30 no.4
• /
• pp.635-648
• /
• 2020

Performance improvement of helical piles in static load tests using hexagon joints that do not require welding or bolting was investigated. Two sites were selected for pile field tests to evaluate their bearing capacity. Static and pull-out load tests were undertaken to assess the method for estimating bearing capacity. The field tests indicated that the bearing capacity of the gravity grout pile was ≥600 kN in the static load test, consistent with the AC 358 Code. The non-grout pile had a bearing capacity of ≤600 kN, suggesting that gravity grouting is required. Field pile load-test results were used to establish the bearing capacity equation, based on a small number of helical pile.

• Journal of the Korean GEO-environmental Society
• /
• v.17 no.10
• /
• pp.55-62
• /
• 2016

The frequency slope over a year due to climate collapse is connected with huge casualties and property damage, but the situation rarely reduce the damage that gradually increases in size. In order to suppress this, engineers are improved better reinforcement and continued efforts to improve the shear force or withdrawal force. In this study, the GangWhaGu attached to the nail tip that improves the soil nail pullout resistance, and a method to increase the nail integral GangWhaGu maximize the contact area soil - by increasing the friction of the grout seems to increase the effect of slope stability. In order to validate the experiment to determine the effect of reinforcing the soil nail pullout tests of indoor and Behavior GangWhaGu nail and through field tests were conducted and applicability. Experimental results, the case of a pull-out test compared to the GangWhaGu nail through the tensile force of the nail were to increase by approximately 20%.

• Journal of the Korean GEO-environmental Society
• /
• v.14 no.3
• /
• pp.19-27
• /
• 2013

Recently, the natural and man-made slope collapses occur frequently because of sudden heavy rains. So, a variety of slope reinforcement methods have been developed and applied to failure slopes. Soil nailing method usage has been increased because of its workability and economic aspects. This method has been applied in combination with other slope stability methods. Soil nailing method is a kind of combinational structure of steel bar and cement grouting. This method uses skin friction between adjacent ground and cement grouting to stabilize the slope. In this study, End-expanded soil nailing method was developed. This method consists of steel bar and anchor body attached at the tip of the nail. During construction, the anchor body at steel bar tip is settled to the ground through the expanding action. In this study, field pull-out tests were performed for un-grouting soil nailing and grouting soil nailing. From the test results, a wedge force of End-expanded soil nailing method was analyzed. And the behavior characteristics of End-expanded soil nailing were studied.