• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.114-125
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• 1993

Thermoelastoplastic analysis of a typical device consisting of fixed tube and movable case having an inital clearance in between, which is subjected to pressure and thermal load, has been carried out to examine the cause of malfunction mainly at high temperature condition, and to improve the design. Stresses, deformed shape, interface state and their effects on normal function of case are discussed by using finite element method. The extraction energy can be remarkably reduced by changing the configuration of tube from the present design (Parallel type) to the improved design (Tapered type). This effect has been proved by sustained cyclic function test.

• Journal of Drive and Control
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• v.17 no.4
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• pp.97-102
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• 2020

This paper presents the basic research for the design and fabrication of a 3D-printed load cell made of NCPC (nano-carbon piezo-resistive composite). We designed a structure that can resonate at a low frequency range of about 5-6 Hz with ANSYS using sensitivity analysis and a response surface method. The design was verified by fabricating the device with a low-quality commercial 3D printer and ABS filament. We conducted a feasibility test for a commercial sensor using 1000 cyclic load tests at 0.3 Hz in a material testing system. A manufacturing process for the 3D printer filament based on the NCPC was also developed using the nano-composite process.

• Geotechnical Engineering
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• v.14 no.3
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• pp.47-62
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• 1998

The disturbed state concept (DSC) proposed here is based on the idea that a deforming material element can be treated as a mixture of two constituent parts in the relative intact (Rl) and fully adjusted (FA) states, referred to as reference states. Based on this idea, DSC provides a unified constitutive model for the characteristics of saturated sands under cyclic loading. The model parameters for saturated sands are evaluated by using data from truly triaxial test device, The laboratory test results are also used for the verification of D SC model. In general, the model predictions are found to provide satisfactory correlation with the test results. From the results of this research, it can be stated that the DSC model is capable of characterizing the cyclic behavior of saturated sands under dynamic loading.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.335-343
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• 2008

In order to improve the workability in erecting Precast Concrete (PC) members and enhance the seismic resistance capacity of the joints in PC moment frames, a new PC column and its construction process are introduced in this paper. This column is manufactured by centrifugal force in keeping the hollow tube inside; the hollow is little bit wide and the grout can be poured from top to bottom after erection at site so that more compact grouting is possible in horizontal joint. The repeated cyclic loading test for four full scaled specimens was conducted to evaluate the seismic resistance capacity of the joint designed by the proposed system. For the continuity of main reinforcements in column, two connecting methods are used in designing specimens; one is to use mechanical connector and other is lab splice. From the cyclic lateral loading test, it was found that the seismic capacity of the developed PC column joint is comparable to that of monolithic joint.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1527-1532
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• 2008

45% of the sports accidents is the knee damage and the representative case is the damage of an Anterior Cruciate Ligament (ACL) and the Posterior Cruciate Ligament(PCL). Although the past different views of ACL reconstruction comes to an agreement, the disputes of PCL is remained yet. The most important engineering approach for these various surgery techniques is accurately to understand and to evaluate the fatigue behavior depending on the stress flow and the stress distribution under the allotted load and the cyclic load, which are caused by the graft fixing device, the proximal tibia of the PCL reconstructing structure. Therefore, this study is the basic research of these above facts. The current transtibial tunnel surgery using the cadaveric Achilles tendon grafts is chosen for the various PCL reconstruction. The relationships between the slippage, the extension ratio, and the slippage ratio by the heel bone fixing method and the soft tissue fixing method of the Achilles tendon were also defined. This research will be the essential data to help the resonable operating techniques for the next PCL reconstruction.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.73-80
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• 2004

In this paper, we present the cell resequencing buffer to solve the cell sequence integrity problem of the Cyclic banyan network that is a high-performance fault-tolerant cell switch. By offering multiple paths between input ports and output ports, using the deflection self-routing, the Cyclic banyan switch offer high reliability, and it also solves congestion problem for the internal links of the switch. By the way, these multiple paths can be different lengths for each other. Therefore, the cells departing from an identical source port and arriving at an identical destination port can reach to the output port as the order that is different from the order arriving at input port. The proposed cell resequencing buffer is a hardware sliding window mechanism. to solve such cell sequence integrity problem. To calculate the size of sliding window that cause the prime cost of the presented device, we analyzed the distribution of the cell delay through the simulation analyses under traffic load that have a nonuniform address distribution that express tile Property of traffic of the Internet. Through these analyses, we found out that we can make a cell resequencing buffer by which the cell sequence integrity is to be secured, by using a, few of ordinary memory and control logic. The cell resequencing buffer presented in this paper can be used for other multiple paths switching networks.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.183-194
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• 2017

This paper presents the experimental investigation into a new type of steel-concrete hybrid outrigger system developed for the high-rise building structure. The steel truss is embedded into the reinforced concrete outrigger wall, and both the steel truss and concrete outrigger wall work compositely to enhance the overall structural performance of the tower structures under extreme loads. Meanwhile, metal dampers of low-yield steel material were also adopted as a 'fuse' device between the hybrid outrigger and the column. The damper is engineered to be 'scarified' and yielded first under moderate to severe earthquakes in order to protect the structural integrity of important structural components of the hybrid outrigger system. As such, not brittle failure is likely to happen due to the severe cracking in the concrete outrigger wall. A comprehensive experimental research program was conducted into the structural performance of this new type of hybrid outrigger system. Studies on both the key component and overall system tests were conducted, which reveal the detailed structural response under various levels of applied static and cyclic loads. It was demonstrated that both the steel bracing and concrete outrigger wall are able to work compositely with the low-yield steel damper and exhibits both good load carrying capacities and energy dispersing performance through the test program. It has the potential to be applied and enhance the overall structural performance of the high-rise structures over 300 m under extreme levels of loads.

• Steel and Composite Structures
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• v.27 no.6
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• pp.661-674
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• 2018

Seismic excitations may impart a significant amount of energy into structures. Modern structural design attitudes tend to absorb some part of this energy through special dissipaters instead of heavy plastic deformations on the structural members. Different types of dissipater have been generated and utilized in various types of structures in last few decades. The expected earthquake damage is mainly concentrated on these devices and they may be replaced after earthquakes. In this study, a low-cost device called energy dissipative steel cushion (EDSC) made of flat mild steel was developed and tested in the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University (ITU). The monotonic and cyclic tests of EDSC were performed in transversal and longitudinal directions discretely. Very large deformation capability and stable hysteretic behavior are some response properties observed from the tests. Load vs. displacement relations, hysteretic energy dissipation properties as well as the closed form equations to predict the behavior parameters are presented in this paper.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.399-407
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• 2010

The flexural behaviors of two types of beam members exposed to freeze-thaw cycles were evaluated. This study aims to examine the effect of freeze-thaw cycles on the behavior characteristics of reinforced concrete (RC) beams. For the purpose, a part of the beam specimens were damaged until yielding of tension reinforcement was reached, before they were exposed to 150 and 300 cycles of freeze-thaw. Cyclic tests, as well as monotonic tests, were conducted to evaluate the stiffness degradation characteristics when same cycle is repeated. The material tests showed that relative dynamic modulus of concrete exposed to 300 cycles of freeze-thaw moderately decreased to 86.8% of normal concrete, indicating that concrete used in this study has good durability against freeze and thaw damage. The results of monotonic tests showed reduction of flexural strength, ductility and stiffness of the beam specimens exposed to freeze-thaw cycles compared with those of the control speciments. In particular, BDF13 specimens, which had been subjected to artificial cracking damage, did not showed enough flexural strength to satisfy nominal moment required by current concrete structure design code. In the monotonic tests results, BF75 specimens exposed to freeze-thaw cycles showed 10% or more cyclic stiffness degradation. Therefore, it was thought that deformation of concrete in compression have to be considered in design process of members under cyclic load, such as seismic device.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.583-594
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• 2000

Dislodgement of a crown or extension bridge and the loosening of a retainer of a bridge is a serious clinical problem in fixed restoration. Generally these problems are considered to be associated with deformation of the restoration. During biting, the restoration is subjected to complex forces and deforms considerably within the limit of its elasticity. Deformation of the restoration under the occlusal force induces excessive stress in the cement film, which then leads to the cement fracture. Such a fracture may eventually cause loss of the restoration. Because most of the past retention tests for full veneer crown were done without fatigue loading, they were not exactly simulating intraoral environment. And the purpose of this study was to evaluate the effect of cyclic cantilever loading on the retentive strength of full veneer crowns depending on different type of cements and taper of prepared abutment. Steel dies with $8^{\circ}\;or\;16^{\circ}$ convergence angle were fabricated through milling and crowns with the same method. These dies and crowns were divided into 8 groups. Group 1 : $16^{\circ}$ taper die, cementation with zinc phosphate cement, without loading Group 2 : $16^{\circ}$ taper die, cementation with zinc phosphate cement, with loading Group 3 : $8^{\circ}$ taper die, cementation with zinc phosphate cement, without loading Group 4 : $8^{\circ}$ taper die, cementation with zinc phosphate cement, with loading Group 5 : $16^{\circ}$ taper die, cementation with Panavia 21, without loading Group 6 : $16^{\circ}$ taper die, cementation with Panavia 21, with loading Group 7 : $8^{\circ}$ taper die, cementation with Panavia 21 without loading Group 8 : $8^{\circ}$ taper die, cementation with Panavia 21, with loading After checking the fit of die and crown, the luting surface of dies and inner surface of crowns were air-abraded for 10 seconds. The crowns were cemented to the dies, with cements mixed according to the manufacturer's recommendations. A static load of 5kg was then applied for 10 minutes with static loading device. Twenty-four hours later, group 1, 3, 5, 7 were only thermocycled, group 2, 4, 6, 8 were subjected to cyclic loading after thermocycling. Retentive tests were performed on the Instron machine. From the finding of this study, the following conclusions were obtained 1. Panavia 21 showed significantly higher retentive strength than zinc phosphate cement for all groups (p<0.05). 2. There was a significant difference in the retentive strength between $8^{\circ}\;and\;16^{\circ}$ taper for zinc phosphate cement(p<0.05), but no significant difference for Panavia 21 (p>0.05). 3. Cyclic loading significantly decreased the retentive strength for all groups(p<0.05). 4. For zinc phosphate cement, there was 35% reduction of the retentive strength after loading in the $16^{\circ}$ taper die, 25% in the $8^{\circ}$ taper die, and for Panavia 21, 21% in the $16^{\circ}$ taper die, 18% in the $8^{\circ}$ taper die.