• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.3-10
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• 1999

There is an increasing demand for using rock anchors as foundations in many geotechnical engineering structures such as transmission towers, dams, etc. For investigate the behavior and strength of rock anchors, in-situ pull-out tests were carried out. From the tests, various forms of failure of rock anchors were observed. Ultimate capacity of each failure modes of 1) Tendon failure, 2) Interface failure(tendon-grout interface, sheath-grout interface and grout-rock interface), 3) Combined interface failure, was obtained by varying the parameters such as diameter and length of tendon, grout strength, and quality of rock.

• Korean Institute of Interior Design Journal
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• v.21 no.2
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• pp.174-185
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• 2012

The purpose of this study is to suggest planning strategy of tenant mix for UEC based on the final result of tenant mix analysis of five different research cases. The following is the comprehensive explanation about the result of tenant mix planning strategy for UEC currently in operation and when planning a new facility. First, overall research cases in this study show the tendency of following an old tradition, which stresses direct sales focusing on retail and dining adaptation. In order to compensate the defect, it is suggested to adopt new type of tenants with the functional mix of retail and dining with entertainment rather than decreasing the proportion of retail and dining tenant and increasing it of entertainment tenant. Second, the floorplan of UEC should adopt racetrack or circuit form that can stimulate shoppers' circular movement so to expose them to as much tenants as possible. Service consumption mode related tenants are required to place on the side or the edge of UEC, while retail consumption mode related tenants should be planned in the center. Among dining consumption mode related tenants, impulse dining tenants like a coffee shop should be placed at the turning point or at the end of the pathway, destination tenants like a restaurant and a food court, on the other hand, is needed to be placed in the center of the space. In case of Entertainment related tenants, destination tenants like bookstore or multiplex should also be placed at the end of the pathway, and on the way to those tenants, it is required to place general tenants that can share target customers with them. On the contrary, game center or record shop like tenants that can stimulate impulse sales should be placed on the visitor's main move or near the other destination tenants. Third, anchor tenants play an important role in gathering people to the UEC, and then induce them to visit the other tenants that are located near the anchors. Thus it is suggested to plan to place general tenants on the same floor as anchor tenants are placed so they can share the characteristics of target customers which create synergy effect.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.121-128
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• 2016

In order to suggest a reasonable design for the circular concrete filled tube steel column-foundation connection applying high-tension bolts, Overall structural behavior and characteristics according to various variables of column-foundation connection are numerically analyzed using a commercial FE analysis program, ABAQUS. To that goal, finite element analysis is conducted on the basis of the previous study replacing anchor bolts to high-tension bolts, and the analytical results are validated by comparison with experimental results. Also, the various variables(embedded depth and grade of anchor, and height and thickness of rib) involved in behavior of the column-foundation connection are selected through analyzing the current design criteria, and the characteristics of the column-foundation connection are compared and analyzed according to the various variables. In case of the anchor bolts, Applying the high-tension bolts is more advantage and securing the embedded depth beyond 0.5D is recommendable. In case of the rib, a minimum of 0.5D for rib's height and $0.4t_b$ for rib's thickness should be secured to develop the structural performance.

• Geotechnical Engineering
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• v.13 no.5
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• pp.45-58
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• 1997

In this paper the factors developing ground disturbance with the penetration of PDB mandrels are analysed by using field reconnaissance and laboratory test. In the laboratory tests, the amount of smear zones around the PDB mandrels is compared with respect to the shape and the size of mandrels by penetrating model mandrels of various shapes into the reconstituted clay. The shapes of mandrels selected are circular, oval and rectangular. It was recognized from the field reconnaissance that the size and shape, driving techniques of mandrels, as well as the size and shape of anchor shoe could develop ground disturbance. The mandrels that would reduce the smear effect of clay is oval and rectangular shapes rat her than circular one. It was found that the smear effect becomes smaller as the ratio of the long and short edge of the rectangular shape mandrel becomes larger.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.75-82
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• 2015

An experimental study has been carried out to examine development length effects for high strength headed deformed bars. Current design codes limit the specified yield strength of headed bars to 400 MPa. Such the limit is due to the lack of experimental studies on headed bars made of high strength materials. Thus a test program was planed with headed bars with the yield strength of 600 MPa. The threaded head type with head shapes of round plate and circular cone was selected in this study. The experimental variables were development length, number of bars, and head shape. Specimens were classified into L-type and S-type depending on the development length. The development length of L-type was computed according to the design code without considering the limit. S-type specimens had shorter development lengths than the L-type. Further classification was made depending on the shape of heads. A-types have the head shape of round plate and B-types have the shape of circular cone. Three L-type specimens were fabricated with the variable of number of bars (1, 2, and 3). Four specimens for each of SA and SB types were made with development lengths of 50%, 45%, 40%, and 35% compared with L-type. Pullout tests was carried out with 11 specimens. The test results were compared with computed strengths with the design code equations (Appendix II). Based the current studies, it can be said that high strength headed deformed bars used in this study be able to provide such strengths computed with the current design code without considering the yield strength limit.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.2 s.5
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• pp.95-104
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• 2002

This paper presents the pull-out failure mode on Headed Bars and prediction of tensile capacity, as governed by concrete cone failure. 17 different plate types, three different concrete strengths and three different welding types of specimens were simulated. Test variables are the reinforcing bar diameters connected to headed plate (e.g., 16mm, 19mm and 22mm), the head plate shapes (e.g., circular, square, rectangular), the dimensions of head plates (e.g., area and thickness), the types of welding scheme for connection of reinforcing bars and head plates (e.g., general welding and friction welding). Headed Bars were manufactured in different areas, which shape and thickness are based on ASTM 970-98. Calculation of Embedment length in concrete is based on CSA 23.3-94, and static tensile load was applied. Pullout capacities tested were compared to the values determined using current design methods such as ACI-349 and CCD method. If compare experiment results and existings, Headed bar expressed high strength and bigger breakdown radious than standard by wide plate area and anomaly reinforcing rod unlike anchor.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.38-49
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• 1988

This paper presented as follows results of laboratory model tests with various shaped footings on soil bed reinforced with the strips on the base of behaviour of soil structure according to the loads and triaxial test results reinforced with geotextiles. Their parameters studied were the effects on the bearing capacity of a footing of the first layer of reinforcement, horizontal and vertical spacing of layers, number of layers, tensile strength of reinforcement and iclination load to the vertical 1.Depending on the strip arrangement, ultimate bearing capacity values could be more improved than urreinforced soil and the failure of soil was that the soil structure was transfered from the macrospace to microspase and its arrangement, from edge to edge to face to face. 2.The reinforcement was produced the reinforcing effects due to controlling the value of factor of one and permeable reinforcement was never a barrier of drainage condition. 3.Strength ratio was decreased as a linear shape according to increment of saturation degree of soil used even though at the lower strength ratio, the value of M-factor was rot influenced on the strength ratio but impermeable reinforcement decreased the strength of bearing capacity. 4.Ultimate bearing capacity under the plane-strain condition was appeared a little larger than triaxial or the other theoretical formulars and the circular footing more effective. 5.The maximum reinforcing effects were obtained at U I B=o.5, B / B=3 and N=3, when over that limit only acting as a anchor, and same strength of fabric appeared larger reinforcing effects compared to the thinner one. 6.As the LDR increased, more and more BCR occurred and there was appeared a block action below Z / B=O.5, but over the value, decrement of BCR was shown linear relation, and no effects above one. 7.The coefficient of the inclination was shown of minimum at the three layers of fabrics, but the value of H / B related to the ultimate load was decreased as increment of inclination degree, even though over the value of 4.5 there wasn't expected to the reinforcing effects As a consequence of the effects on load inclination, the degree of inclination of 15 per cent was decreased the bearing capacity of 70 per cent but irnproved the effects of 45 per cent through the insertion of geotextile.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.47-57
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• 2006

The shear wave velocity is related with the stiffness of granular skeleton and mass density. The shear stiffness of the granular skeleton remains unaffected by the presence of the fluid. Bender elements are convenient shear wave transducers for instrumenting soil cells due to optimal soil-transducer coupling. This study addresses the principles of the shear wave, the design and implementation of bender elements including electromagnetic coupling prevention, directivity, resonant frequency, detection of first arrival, and near field effects. It is shown that electromagnetic coupling effects can be minimized using parallel-type bender elements. Thus, the in-plane S-wave directivity is quasi-circular. The resonant frequency of bender element installations depends on the geometry of the bender element, the anchor efficiency and the soil stiffness. One of the most cumbersome parts in the bender element test is near field effects, which affect the selection of arrival time. The selection of the first arrival within the near field Is effectively solved by the multiple reflection technique and signal matching technique. Bender elements, which requires several considerations, may be effective tools for the subsurface characterization by using S-wave.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.100-117
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• 2020

National Treasure no. 101, the stupa of State Preceptor Jigwang from the Beopcheonsa Temple Site in Wonju has been transferred from place to place and reassembled several times since it was built. In particular, overall dismantling and repair was carried out in 1957 to restore parts damaged by bombing during the Korean War. Documented information on the repair process and materials used at that time does not exist. However, various types of metal materials used for this stupa have been identified during conservation work. Besides clamps anchor bolts, 9mm-thick circular rebars were mainly used for joining the parts of this stupa, while circular rebars and wires of various thicknesses were used for joining the parts with mortar restoration materials. Although deformed bars are typically used for stone pagodas classified as architectural structures, smooth circular rebars were used in this case. In terms of restoration using mortar, material shapes were transformed, bound alternately, and twisted irregularly to improve bonding strength and coherence in order to insert restoration materials and to bolster structural weaknesses. In addition, metallographic analysis showed the material to be hypo-eutectoid steel with low carbon content. Many non-metallic inclusions in the shape of drops of different sizes were included, which do not affect the whole elemental composition due to the very small quantities involved. Qualitative and EPMA analysis of Mn and S, which were not identified by SEM-EDS area analysis, established an even distribution of MnS in crystal grains of the microstructure, regardless of the shape of the samples. It is presumed that secondary homogenization and softening might have been conducted after manufacturing to facilitate the working process. Furthermore, in consideration of properties indicating that the thinner the steel is, the less carbon content contained and the greater the elasticity and elongation, it is judged that restoration work was ordered.

• Journal of the Korean GEO-environmental Society
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• v.17 no.11
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• pp.15-21
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• 2016

Nowadays, some studies have been performed for rockbolt method widely used in Korea. To make large slopes, tunnels or rock structures stable, supporting systems, such as anchor bolt, rock bolt which are developed recently, are commonly used. In this study, laboratory pullout tests were carried out to compare the characteristics of rock bolt that is most widely used with ones of rock bolt by newly developed circular model testers. Re-pullout test for the rock bolt in which loading and unloading cycles are repeated several times showed that the maximum pullout load is almost constant irrespective of the number of loading cycles, which may be due to no failure between rock bolt and filler that is filled with soils and concrete as a substitute. A development of rock bolt fillers as supporters using to protect people in tunnels and slopes is reviewed as a probable man-made hazard after excavation works. The functions of the grouted rock bolts associated with reinforcement effects also should be assessed in this study, which develop the sealing apparatus preventing from overflowing mortar out of a rock bolt hole for securing safety in the tunnel and slopes in order to secure stability named the sealing packer.