• IEIE Transactions on Smart Processing and Computing
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• v.5 no.5
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• pp.331-336
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• 2016

Multi-bit tries have been proposed to improve the search performance of a binary trie by providing flexibility in stride values, which identify the number of bits examined at a time. However, constructing a variable-stride multi-bit trie is challenging since it is not easy to determine a proper stride value that satisfies the required performance at each node. The aim of this paper is to identify several desired characteristics of a trie for IP address lookup problems, and to propose a multi-stride decision trie that has these characteristics. Simulation results using actual routing sets with about 30,000 to 220,000 prefixes show that the proposed multi-stride decision trie has the desired characteristics and achieves IP address lookup using 33% to 47% of the 2-bit trie in the average number of node accesses, while requiring a smaller amount of memory.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.620-626
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• 2014

In this paper, we propose a parallel collaborative sphere decoder with a scalable architecture promising quasi-maximum likelyhood performance with a relatively small amount of computational resources. This design offers a hardware-friendly algorithm using a modified node operation through fixing the variable complexity of the critical path caused by the sequential nature of the conventional sphere decoder (SD). It also reduces the computational complexity compared to the fixed-complexity sphere decoder (FSD) algorithm by tree pruning using collaboratively operated node operators. A Monte Carlo simulation shows that our proposed design can be implemented using only half the parallel operators compared to the approach using an ideal fully parallel scheme such as FSD, with only about a 7% increase of the normalized decoding time for MIMO dimensions of $16{\times}16$ with 16-QAM modulation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.463-470
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• 1998

The boundary/finite element analysis for the seismic wave amplifications due to nonhomogeneous alluvial deposits was performed in this study. For numerical analysis, the homogeneous linear elastic soil half-space was modeled by using the 3-node isoparametric boundary elements and the inhomogeneous alluvial deposit was modeled by using the 8-node isoparametric finite elements. The two elements at interface were coupled together by the equilibrium condition of the tractions and the compatibility condition of the displacements. As a prarmetric variable, the incident angle and the dimensionsless frequency of the SH, P and SV-waves and the shear wave velocity ratio and the mass density ratio between the half-space and the alluvial deposit were selected.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.9-15
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• 1990

In this study, an adaptive mesh h-refinement procedure was presented in plate bending problems. By introducing the transition elements for the procedure, same drawbacks due to the irregular nodes are eliminated which are generated in the consequence of local mesh refinement in common adaptive h-version performed by single type of quadrilateral elements. For the above objective, compatible 5-node through 7-node transition plate bending elements are developed by including variable number of midside nodes. Using the Zienkiewicn-Zhu error estimator, some numerical examples are presented to show the effectiveness of the adaptive h-refinement using the transition elements.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.2
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• pp.63-68
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• 2004

This paper presents an approach to optimum design of Moving Magnet Type Linear Oscillatory Actuator(MM-LOA). The Finite Element Method is applied to characteristic parameters for characteristic analysis and in order to reduce modeling time and efforts, the moving model node technique is used. In addition the neural network is used to reduce computational time of analysis according to changing design variable. To confirm the validity of this study, optimum design results are compared with results of analysis procedure that is verified by experiment.

• Archives of Plastic Surgery
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• v.45 no.3
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• pp.275-279
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• 2018

Chronic lymphedema is caused by an impairment of the lymphatic system due to primary or secondary causes. Vascularized lymph node transplantation (VLNT) is currently the most promising and frequently used technique besides lymphaticovenous anastomosis. However, the vessel anatomy in the lateral thoracic region is sometimes quite variable. Based on our experiences with vascular anatomical inconstancy in the lateral thoracic region, we planned a lateral intercostal artery perforator flap for VLNT in a female patient with chronic stage II lymphedema of both legs after cervical cancer treatment. After surgery, the patient reported significant improvement in limb volume and the accompanying symptoms. The limb circumference was reduced by an average of 19.2% at 6 months postoperatively. Despite having a short pedicle and small vessel caliber, the lateral intercostal artery perforator flap can safely be used for VLNT in lymphedema patients with anatomical variants.

• The Korean Journal of Applied Statistics
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• v.19 no.2
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• pp.271-282
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• 2006

The aim of this study is to propose a tree-structured clustering for mixed data. We suggest a scaling method to reduce the variable selection bias among categorical variables. In numerical examples such as credit data, German credit data, we note several differences between tree-structured clustering and K-means clustering.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.39-46
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• 2018

Departure Manager (DMAN) is a tool to optimize the departure sequence and to suggest appropriate take-off time and off-block time of each departure aircraft to the air traffic controllers. To that end, Variable Taxi Time (VTT), which is time duration of the aircraft from the stand to the runway, should be estimated. In this paper, a study for development of VTT prediction algorithm based on machine learning techniques is presented. The factors affecting aircraft taxi speeds were identified through the analysis of historical traffic data on the airport surface. The prediction model suggested in this study consists of several sub-models that reflect different types of surface maneuvers based on the analysis result. The prediction performance of the proposed method was evaluated using the actual operational data.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.401-407
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• 2000

An elastic-plastic finite element analysis is performed to investigate detailed closure behavior of fatigue cracks and the numerical results are compared with experimental results. The finite element analysis performed under plane stress using 4-node isoparametric elements can predict fatigue crack closure behavior. The mesh of constant element size along crack surface can not predict the opening level of fatigue crack. The crack opening level for the constant mesh size increases linearly from initial crack growth. The crack opening level for variable mesh size, is almost flat after crack tip has passed the monotonic plastic zone. The prediction of crack opening level using the variable mesh size proportioning the reversed plastic zone size with the opening stress intensity factors presents a good agreement with the experimental data regardless of stress ratios.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.60-67
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• 1998

This paper deals with the development of a variable-node element and its application to the adaptive h-version mesh refinement-recovery for the incompressible viscous flow analysis. The element which has variable mid-side nodes can be used in generating the transition zone between the refined and unrefined elements and efficiently used for construction of a refined mesh without generating distorted elements. A modified Gaussian quadrature is needed to evaluate the element matrices due to the discontinuity of derivatives of the shape functions used for the element. The penalty function method which can reduce the number of independent variables is adopted for the purpose of computational efficiency and the selective reduced integration is carried out for the convection and pressure terms to preserve the stability of solution. For the economical analysis of transient problems, not only the mesh refinement but also the mesh recovery is needed. The numerical examples show that the optimal mesh for the finite element analysis of a wind around the structures can be obtained automatically by the proposed scheme.