• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.94-102
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• 2020

Precast concrete segment arch system has an economic and construct ability that combined with advantage of precast concrete and arch behavior. A precast concrete segment arch system with outrigger is consisted of segmented precast panels, a steel outrigger rib, and V-strip to connect precast panels with a steel outrigger rib and cast-in-place anchors in precast panels to connect V-strip should have sufficient pull-out capacity to form its arch shape by site lifting for assembled precast panels and outriggers. However, it is difficult to secure its embedment depth due to the relatively shallow thickness of precast panel. It can be also occurred that flexure deformation of precast panels caused by its pull-out behaviors. In this study, pull-out capacity of cast-in-place anchor was examined for construction of precast concrete segment arch system with outriggers. Therefore, a total of 24 precast panel specimens were fabricated to examine pull-out capacities of cast-in-place anchor in precast panels, and installation depth of anchors, diameter of anchors and wire mesh effects for the precast panel were examined. From this pull-out tests, its pull-out capacities and failure modes were evaluated and the type of the cast-in-place anchor applicable to the precast concrete segment panel arch system with outriggers was determined from comparison of the design specification values.

• Journal of the Korean Wood Science and Technology
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• v.7 no.1
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• pp.8-11
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• 1979

The apparatus for measuring the static withdrawal resistance of nail is the AUTOGROPH S-500 static testing machine. The nails were 0.25 - 0.26 cm in diameter, 4.9-5.1cm in length, and were driven into wood for a depth of 3.0 cm. The physical properties of wood specimens are shown in table 1. Some data obtained in this experiment are as follows 1) The effects of the direction of driving and the time after driving upon static withdrawal resistance are shown in fig. 2-3. 2) The relations between static withdrawal resistance are moisture content of wood are characterized by nearly straight line as shown in fig. 4-5. The empirical formula areas follows: Y = -0.074 x + 12.73 (Pinus koraiensis Sieb & Zucc. - radial) Y = -0.073 x + 7.54 (Pinus koraiensis Sieb & Zucc. - longitudinal) Y = -0.061 x + 12.80 (Larix leptolesis Gord. - tangential) Y = -0.081 x + 7.61 (Larix leptolepsis Gord. - longitudinal) Where Y is the static withdrawal resistance ($kg{\cdot}cm$) and x is the moisture content(%).

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

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.250-253
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• 2007

It is known that fine straightness of micro-wire can be obtained by removing residual stress induced during the manufacturing processes. Generally, residual stress is removed or minimized through several drawing processes with heat treatment. In this study, the residual stress at each straightening process is calculated and monitored by finite element analyses and the main reason of stress change is investigated.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.249-250
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• 2006

Bi-2212/Ag ROSAT용 와이어의 제작은 PIT법으로 제작된 단일 필라멘트가 사용되었다. 제작된 필라멘트를 압연하여 너비 8.6mm, 두께 2.15mm의 압연 테입을 제조한 후 4개씩 적층하여 3 부분의 마름모로 만들어 다시 내경 17.2mm의 Ag튜브에 적층하여 ROSAT 와이어를 약 150 mm로 제작하였다. 제작된 ROSAT 와이어는 산소분위기에서 약 60시간 동안 열처리 되었다. 이때 열처리 온도와 최고점에서의 유지시간에 따른 Bi-2212/Ag ROSAT 와이어의 전기적 특성을 평가 하였다. 기존의 Bi-2212/Ag 와이어에 비해 압연, 적층, 인발하여 제작된 동일한 크기의 ROSAT 와이어가 향상된 전기적 특성을 나타내었다.

• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.27-34
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• 2017

This study was carried out to estimate structural stabilities in respect of ground footings of plastic greenhouses on reclaimed lands. A 6m-wide multi-span plastic greenhouse with steel spiral piles as well as two 8.2m-wide single-span greenhouses with steel spiral piles and continuous pipe foundation respectively were built up on a reclaimed land with a SPT N-Value of 2 and measured how much the greenhouses were lifted up and subsided. In addition, the uplift capacity of three kinds of spiral piles(${\phi}50$, ${\phi}75$ and ${\phi}100$) was determined on a nearby reclaimed land. The results showed that the greenhouses with spiral piles had a slight vertical displacement like moving up and down but the scales of the rising up and sinking were negligible when compared to that of the greenhouses. The vertical displacement of the multi-span greenhouse ranged from +9.0mm(uplift) to -11.5mm(subsidence). As for the single-span greenhouses with spiral piles and continuous pipe foundation, the measurements showed that it varied from +1.3mm to -7.7mm and from +0.9mm to -11.2mm, respectively. The allowable uplift capacity of spiral piles could all be determined under criteria of ultimate load and accordingly had a value of 0.40kN, 1.0kN and 2.5kN, respectively. It was not entirely certain enough to make a final judgement on structural stabilities in respect of ground footings, it appeared likely however that the greenhouses with steel spiral piles was tentatively observed without any problems on reclaimed lands within the period.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.211-220
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• 2004

This paper presents the evaluation of pullout strengths of expansion anchors and wedge anchors that can cause a failure of the concrete on the basis of the design for anchorage. Tests are conducted for heavy-duty anchors and wedge anchors domestically manufactured and to be installed in plain concrete member. The mainly testing parameters reflected the effects of edge distance. Design of post-installed steel anchors is presented by the Concrete Capacity Design(CCD) in European Organization for Technical Approval. This approach is compared to the well-known provisions, ACI 349-90 specification. The use of both methods to predict the concrete failure load of expansion anchor in uncracked concrete under monotonic loading for important applications is compared. In this study, the concrete tension capacity of fastenings with Heavy-duty Anchors and Wedge Anchors in plain concrete predicted by ACI 349-90 and the Concrete Capacity Design method has been compared with the results of tests.

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.45-54
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• 2019

This paper describes the results of finite element analysis (FEA), in order to investigate a characteristics of pile pullout behavior according to the conditions of the relative density and fines content in original ground. In the FEA, a boundary elements and strength reduction factors ($R_{inter}$) on pile-soil interface were applied to simulate appropriately the shear behavior at the pile-soil interface, and then the reliability of numerical analysis method was verified by comparison of FEA results and previous experimental research(You et al., 2018). In addition, a the deformation characteristics at the pile-soil interface and determination method of $R_{inter}$ value was laid out. The results showed that the FEA, based on the analytical model applied in this study simulates appropriately the characteristics of the pile-soil interface by pullout model test of pile. In order to apply the suggested $R_{inter}$ value, it is necessary to consider the condition of the relative density and the fines content in ground.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.8-15
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• 2021

This study presents post-installed anchors whose heads and extension sleeves are improved. The optimal lengths of the extension sleeves and headers were analytically determined by simulations. As a result of analysis using Finite element method (FEM), 9.0mm and 3.0mm were determined as the optimal lengths of sleeves and headers respectively. In pull-out tests using the improved post-installed anchors, all specimens satisfied the coefficient of variation of 15%. Comparing the pull-out strengths of existing anchors and the improved anchors, it was increased by 1.25 times for anchors embedded with a depth of 50mm, and 1.54 times for 70mm. In the cases of high-strength concrete, the strengths were increased by 1.28 and 1.55 times for 50mm and 70mm respectively. Moreover, as a result of shear tests, the improved anchors perform the greater strength of 1.38 times than the existing anchors.