• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.288-295
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• 2003

An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the recovery technique. In case of the recovery technique, the SPR(superconvergent patch recovery) approach has been modified for p-adaptive mesh refinement. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly. To verify the proposed algorithm, the limit value approach is proposed which utilizes the exact strain energy computed from the extrapolation equation. A new pre-processor is developed for the p-version finite element program in which the vector graphic editor is used for the automatic generation of node connection and coordinate by halfedge solid data structure according to uniform or nonuniform p-distribution. The general 2-D algorithm is also developed to generate face modes and internal modes in accordance with different mesh types. The quality of the error estimator is investigated with the help of two mumerical examples. The results show that the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.634-640
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• 2000

This paper proposes a new extended decision directed-decision estimated phase recovery algorithm based on maximum likelihood parameter estimation for OQPSK. In this scheme, comparing conventional one, the data dependent noise of phase recovery loop is reduced by inserting filter with 2 taps to in-phase and quadrature-phase channel respectively before phase detector. The proposed scheme is compared to conventionalscheme and OQPSK in aspect to BER(Bit Error Rate) and phase error according to the roll-off factor of baseband filter, the output back-offs of nonlinear satellite channel, and loop bandwidth.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.2936-2951
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• 2016

An emerging satellite technology, Operationally Responsive Space (ORS) is expected to provide a fast and flexible solution for emergency response, such as target tracking, dense earth observation, communicate relaying and so on. To realize large distance transmission, we propose the use of available relay satellites as relay nodes. Accordingly, we apply software defined network (SDN) technology to ORS networks. We additionally propose a satellite network architecture refered to as the SDN-based ORS-Satellite (Sat) networking scheme (SDOS). To overcome the issures of node failures and dynamic topology changes of satellite networks, we combine centralized and distributed routing mechanisms and propose a fast recovery routing algorithm (FRA) for SDOS. In this routing method, we use centralized routing as the base mode.The distributed opportunistic routing starts when node failures or congestion occur. The performance of the proposed routing method was validated through extensive computer simulations.The results demonstrate that the method is effective in terms of resoving low end-to-end delay, jitter and packet drops.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.842-846
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• 2015

In this study, we propose an algorithm of the method of recovering quickly find the location of the error encountered during separate operations in the functional structure of complex digital circuits by mimicking the self-healing function of the cell. By the digital circuit was divided by 9 function block unit of function, proposes a method that It can quickly detect and recover the error position. It was the detection and recovery algorithms for the error location in the digital circuit of a complicated structure and could extended the number of function block for the $3{\times}3$ matrix structure on the digital circuit.

• Convergence Security Journal
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• v.23 no.1
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• pp.3-8
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• 2023

Multi-domain optical transport networks are not fundamentally interoperable and require an integrated orchestration mechanism and path provision mechanism at the entire network level. In addition, ensuring network survivability is one of the important issues. MPLS-TP (Multi-Protocol Label Switching-Transport Profile) defines various protection/recovery methods as standards, but does not mention how to calculate and select protection/recovery paths. Therefore, an algorithm that minimizes protection/recovery collisions at the optical circuit packet integrated network level and calculates and sets a path that can be rapidly protected/recovered over the entire integrated network area is required. In this paper, we proposed an algorithm that calculates and sets up a path that can be rapidly protected and restored in a T-SDN network composed of multiple ring-mesh topology.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.109-112
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• 2000

Bitstrems corrupted by channel errors are not only difficult to be decoded but also propagate error to other part of the bitstreams when highly compressed video is transmitted over channels with noise such as mobile communication channels. In this paper, error concealment algorithm performed in decoder is proposed when errors occur for transmission. Proposed algorithm searches moving area with homogeneous movement in neighbored blocks when motion vectors are damaged, then recovers motion vectors of missing blocks considering where missing blocks are belong to. Experiment result shows that proposed algorithm exhibits better performance in PSNR than existing error concealment method.

• Journal of Astronomy and Space Sciences
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• v.8 no.1
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• pp.115-123
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• 1991

Automatching algorithm is suitable for cross-correlation, which showed correlation surface about maximal correlation coefficient. The size of the window area must be determined empirically, whereas window size generally chosen as a compromise between speed and accuracy. It is possible that epipolar transform prevented from mismatching and decreased search space. In application of the astronomical fields, automatching algorithm mainly used to planet surface recovery in satellite image.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.10
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• pp.1-11
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• 1996

In this paper, we evaluate the performance of DD-bardner (decision-directed gardner) algorithm. We derive an analytic gain of the thiming detector that is a function of SNR and an excess bandwidth, and verify the result by simulation. We also compare the DD-gardner algorithm with the bardner algorithm with respect to tracking performance and jitter performance under low SNR and a residual frequency component.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.288-291
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• 2008

Physics based Cellular Automata model is developed and implemented into FEM code. CA model can predict microstructure evolution based on physical phenomena, such as hardening, recovery and recrystallization. This paper outlines the methodology to determine the materials constants for these different phenomena from simpler measurements.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.44-48
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• 2001

In this paper we describe the design of symbol timing and carrier synchronization algorithms for burst receiver. The demodulator consists of digital down converter, matched filter and synchronization circuits. For symbol timing recovery we use modified Gardner algorithm. And we use decision directed method for carrier phase recovery. For the sake of performance analysis, we compare simulation results with the board implemented by FPGA which is APEX20KE series chip for Alter. The performance results show it works quite well up to the condition that a frequency offset equal to 0.1% of symbol rate.