• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.465-467
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• 2010

This paper proposes MIMO two-way cooperative relay scheme to optimize the end to end capacity in wireless multi-hop mesh network. The basic idea is to perform data transmission via multi-hop relay nodes, in equidistant topology, this method is quite efficient. However, on one hand this topology is very rare in practical situation, on the other hand, in real practical situation where the topology is most likely non equidistant, the end to end capacity significantly degrades due to bottleneck link caused by uneven SNR. Moreover, the end to end capacity degrades at high SNR due to overreach interference from far nodes existing in multi-hop relay networks. In this paper, MIMO two-way cooperative relay in the region of non equidistant nodes is found efficient to improve the end to end capacity. The proposed scheme is validated using numerical simulation.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.243-250
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• 2015

An extended end-plate connection displays different behavioral properties and energy dissipation capacity based on the thickness and length of the end-plate comprising the connection in the form of a beam-to-column moment connection, the number and diameter of the high strength bolt, the gauge distance of the high strength bolt, and the size and length of the welds. Such extended end-plate is applied to beam-to-column connections in various geometric forms in the US and European regions. Currently in Korea, however, the extended end-plate beam-to-column connection is not actively applied due to the lack of proper design formulas, the evaluation of the energy dissipation capacity, and the provision of construction guidelines. Accordingly, this study was conducted to provide the basic data for the proposal of a prediction model of energy dissipation capacity by evaluating the energy dissipation capacity of unstiffened extended end-plate connections with relatively thin end plate thicknesses. To achieve this, a three-dimensional nonlinear finite element analysis has been conducted on unstiffened extended end-plate connections, with the thickness of the end plate as the set variable.

• Steel and Composite Structures
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• v.42 no.4
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• pp.569-590
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• 2022

This paper presents a combined experimental and numerical study on stainless steel end-plate connections, with an emphasis placed on their ultimate behaviour and rotation capacity. In the experimental phase, six connection specimens made of austenitic and lean duplex stainless steels are tested under monotonic loads. The tests are specifically designed to examine the close-to-failure behaviour of the connections at large deformations. It is observed that the rotation capacity is closely related to fractures of the stainless steel bolts and end-plates. In the numerical phase, an advanced finite element model suitable for fracture simulation is developed. The incorporated constitutive and fracture models are calibrated based on the material tests of stainless steel bolts and plates. The developed finite element model exhibits a satisfactory accuracy in predicting the close-to-failure behaviour of the tested connections. Finally, the moment resistance and rotation capacity of stainless steel end-plate connections are assessed based on the experimental tests and numerical analyses.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.884-890
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• 2009

The bi-directional pile load test with variable end plate overcomes the shortcoming of the Osterberg cell test. It is possible that the ultimate bearing capacity of the bi-direction can be known by using the loading of the end plate and two step procedures. The first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell, operated with end plate of 3 type on sand layer according to the relative density, loose, medium and dense conditions.

• Structural Engineering and Mechanics
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• v.21 no.2
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• pp.221-235
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• 2005

In this paper, the shear resistance behaviour of reinforced concrete (RC) dapped end beams is investigated by 24 tests until failure load. The main parameters considered are the dapped end height, the type and effective range to provided the stirrups and the bent form of the longitudinal reinforcement. The failure behaviour of dapped end beams is presented and some conclusions are given. Inclined stirrups and longitudinal bent reinforcement have more influence on the shear capacity than vertical stirrups. Additionally, the shear mechanism of dapped end beams is analysed. Relatively simple semi-empirical equations for shear strength have been derived based on the results of 22 dapped end beams. The predicted results are in close agreement with the experimental ones. Finally, some design suggestions for the ultimate shear strength of dapped end beams are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.74-81
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• 2004

In this study, static end loading tests with load transfer measurement were accomplished for large diameter drilled shaft constructed in fault zone. Yield pile capacity (or ultimate pile capacity) from load-settlement curve was determined and axial load transfer behavior was measurd. The end bearing capacity was increased 2 times due to grouting the toe ground under pile base.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.495-507
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• 2005

Measuring the end-to-end available bandwidth in the Internet is a useful tool for distributedapplication services or QoS (Quality-of-Service) guarantee. To measure the end-to-end available bandwidth, Single-hop Gap model-based packet train measurement techniques are well-known. However, the error of packet train output gap can happen by network topologies. This error of the output gap causes the inaccuracy of the available bandwidth measurement. In this paper, we propose a new end-to-end available bandwidth measurement technique with accurate capacity measurement and fast convergence methods. To solve the erroneous capacity measurement problem of the back-to-back packet train transmission, we propose a new available bandwidth measurement method by decoupling the capacity measurement with the initial gap of the packet train. Also, we propose a new technique to predict the proper initial gap of the packet train for faster convergence. We evaluate our proposed method by the simulation in various topologies comparing with previous methods.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.133-134
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• 2020

The equation of end bearing capacity is applied differently depending on the type of pile, construction method, and load characteristics considering the construction standards. The bearing capacity equation of the design standard is presented in various ways according to the design conditions such as construction method and ground condition, etc. but, It does not reflect the ground strength according to the SPT-N value of weathered rock. This study analyzed the trend of allowable tip bearing capacity by pile diameter through about 480 dynamic loading tests conducted for the construction/quality management of piles for the last 6 years since 2015. The equation for the ultimate end bearing capacity per unit area according to the SPT-N value is presented. The proposed formula of ultimate end bearing capacity per unit area can be applied in the range of 15,000kN/m2 to 30,000kN/m2. The proposed formula, which complements the existing formula, enables pile design and construction/quality management.

• Steel and Composite Structures
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• v.44 no.3
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• pp.339-351
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• 2022

A mortar-filled rectangular hollow structural section (RHS) can increase a structural section property as well as a compressive buckling capacity of a RHS member. In this study, the tensile performance of newly developed mortar-filled RHS members was experimentally evaluated with various connection details. The major test parameters were the type of end connections, the thickness of cap plates and shear plates, the use of stud bolts, and penetrating bars. The test results showed that the welded T-end connection experienced a brittle weld fracture at the welded connection, whereas the tensile performance of the T-end connection was improved by additional stud bolts inserted into the mortar within the RHS tube. For the end connection using shear plates and penetrating stud bolts, ductile behavior of the RHS tube was achieved after yielding. The penetrating bars increased load carrying capacity of the RHS. Based on the analysis of the load transfer mechanism, the current design code and test results were compared to evaluate the tensile capacity of the RHS tube according to the connection details. Design considerations for the connections of the mortar-filled RHS tubes were also recommended.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.589-596
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• 2002

In this study, static pile load tests with load transfer measurement were accomplished in the field. Yield pile capacity (or ultimate pile capacity) determined by load-settlement-time relationship was determined and axial load transfer behavior was analyzed. In the test for the four test piles were behaved as end bearing pile but ratios of skin friction to total pile capacity were 27%∼33%.