• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.171-174
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• 1999

The objective of this study is to investigate the properties of fine particles in the process of producing crushed fine aggregates under various fine particle contents. According to the test results, when fine particles are added as substitution of aggregates by about 10%, it shows that the qualities of interlocking block such as compressive strength, flexural strength and absorption ratio are improved. The application of fine particles provide various advantages in the sides of recycling of materials

• Steel and Composite Structures
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• v.21 no.3
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• pp.461-477
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• 2016

Steel-concrete-steel (SCS) sandwich composite wall has been proposed for building and offshore constructions. An ultra-lightweight cement composite with density1380 kg/m3 and compressive strength up to 60 MPa is used as core material and inter-locking J-hook connectors are welded on the steel face plates to achieve the composite action. This paper presents the numerical models using nonlinear finite element analysis to investigate the load displacement behavior of SCS sandwich walls subjected to axial compression. The results obtained from finite element analysis are verified against the test results to establish its accuracy in predicting load-displacement curves, maximum resistance and failure modes of the sandwich walls. The studies show that the inter-locking J-hook connectors are subjected to tension force due to the lateral expansion of cement composite core under compression. This signifies the important role of the interlocking effect of J-hook connectors in preventing tensile separation of the steel face plates so that the local buckling of steel face plates is prevented.

• Journal of Welding and Joining
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• v.4 no.2
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• pp.47-52
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• 1986

Friction Welds are formed by the mechanisms of diffusion as well as mechanical inter-locking. The severe plastic flow at the interface by the forge action of the process brings the subsurface so close together that detection of any unbounded area becomes very difficult. No reliable method is available so fat to determine the weld quality nondestructively. The paper presents an attempt to determine weld strength quantitatively using the ultrasonic pulseecho method. The new approach calculates the coefficient of reflection based on measured amplitudes of the echoes. This coefficient provides a single quantitative measurement which involves both acoustic energy reflected at the welded interface as well as transmitted across the interface. As a result, it was known that the quantitative relationship between the coefficient and the weld strength (torsional strength) could be drawn.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.203-206
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• 1997

In this paper, the properties of Interlocking block contained blast furnace slag cement are compared with that with O.P.C.(ordinary portland cement) and are analyzed under various mix proportions and the dosage of AE agent. According to the experimental results, compressive strength and flexural strength of interlocking block with blast furnace slag cement are lower than that with OPC. Also the strength and the ratio of absorption decrease with higher dosage of AE agent. although interlocking block with OPC has better performance than that of blast furnace slag in the side of quality, it is worth while to use the blast furnace slag as materials of interlocking block considered the side of recycling of resources and economy.

• Magazine of the Korea Concrete Institute
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• v.6 no.6
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• pp.151-158
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• 1994

In this work, in order to inrprove the flexural strength of hardened portlarid cerncrit paste, mix ing water was reduced to water ccrnent ratio of 0.1 aid water soluble polymer such as hydroxy propyl methyl cellulose was adclelri to the paste to obtain a better dispersion. The paste was kneaded by the twin roll mill for cornpact and homogeneous mixing. The high strength mechanism of the hardened cement paste may be due to the removal of macropores larger than 100${\mu}m$, the reduction of capillary pores acting as the passage of crack propagation, the increase of Young's moculus with iticrease of unhytlratcci cenxxnt ard the incicasc of fracture toughnevs with the crack toughening mechanism (grain bridging, polymer fibril bridging and fritional inter-locking).

• Structural Engineering and Mechanics
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• v.45 no.6
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• pp.853-865
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• 2013

Inflatable panels made of modern and new textile materials can be inflated at high pressure to have a high mechanical strength. This paper is based on the finite element method as a general solution to determine the characteristics of deformed inflatable panels at high pressure in various end and loading conditions. Proposed method is based on the construction of weak form of formulation and application of Reduced Integration Element method (RIE) to solve the numerical problem of shear locking. The numerical results are validated as an outcome of comparison with other published results.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.432-432
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• 2011

Dry adhesion caused by Nanoscale contact comes up to important scientific issue. Herein, we introduce bendable nanohairy locking fastener system with high shear strength and mechanically flexible backing. The polymeric patches like velcro are composed of an array of straight nanohairs with 100 nm diameter and $1{\mu}m$ height. To fabricate high aspect vertical nanohairs, we used UV molding method with appropriately flexible and rigid polyurethane acrylate material on PET substrate. Two identical nanohairy patches are easily merged and locked each other induced by van der Waals force. Because nanohairs can be arrayed with high density ${\sim}4{\times}10^8/cm^2$, we can obtain high shear adhesion force on flat surface (~22 N/$cm^2$). Furthermore, we can obtian nanohairy locking system with maximum shear adhesion ~48 N/$cm^2$ of curved surface due to flexibility of PET substrate. We confirm the tendency that shear adhesion force increases, as radius of curvature increases.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.212-216
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• 2001

Recently, it has been trending toward speed-up not only in the passenger car but in the freight cu. In this study, we thus performed stress analysis for the carbody for high speed container freight car in use and field test of the freight car in Gyungbu-line so that we may utilize the results as a design guide for speed-up hereafter- Five vertical loading conditions due to dynamic effect and the weight of the carbody and the container applied to locking devices of the carbody and its results are compared with that of a test, As a result, we found that there is need to complement the strength of the carbody in some measure when speed up the present freight car.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.625-631
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• 2013

Reliability of a pin puller was predicted by Monte Carlo simulation. The prediction method is based on the stress-strength interference model that failure occurs if the stress exceeds the strength. In this study, the strength is considered as the energy delivered by combustion of pyrotechnics to retreat the pin to a predetermined position, whereas the stress is regarded as the energy required to resist the pin movement. The former mainly depends on the amount of pyrotechnic charge and the latter is governed by several friction forces and the energy dissipation within locking mechanism. Both the variables of stress and strength were computed using an analytical performance model. The method presented here, not depending upon a large number of test item, can be applicable to predict the reliability of other kinds of pyrotechnic devices.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.277-289
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• 2019

In this study, an innovative anchoring approach has been developed dealing with all relevant aspects in consideration of previous works. An ultimate pulling force calculation of anchor is presented from a geotechnical point of view. The proposed umbrella anchor focuses not only on the friction resistance capacity, but also on the axial capacity of the composite end structure and the friction capacity occurring around the wedge. Even though the theoretical background is proposed, in-situ application requires high-level mechanical design. Hence, the required parts have been carefully improved and are composed of anchor body, anchor cap, connection brackets, cutter vanes, open-close ring, support elements and grouting system. Besides, stretcher element made of aramid fabric, interior grouting system, guide tube and cable-locking apparatus are the unique parts of this design. The production and placement steps of real sized anchors are explained in detail. Experimental results of 52 pullout tests on the weak dry soils and 12 in-situ tests inside natural soil indicate that the proposed approach is conservative and its peak pullout value is directly limited by a maximum strength of anchored soil layer if other failure possibilities are eliminated. Umbrella anchor is an alternative to conventional anchor applications used in all types of soils. It not only provides time and workmanship benefits, but also a high level of economic gain and safe design.