• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.27-33
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• 2011

In digital communication system that the Modified Constant Modulus Algorithm (MCMA) reduced the use of the adaptive equalization algorithm to combat the Inter-symbol Interference (ISI). MCMA is relatively brief operation. The major point of MCMA that it only achieves moderate convergence rate and steady state mean square error (MSE). In this paper suggest, MCMA equalization improve the performance with parallel structure. It combines Modified Constant Modulus Algorithm(MCMA) and Modified Decision Directed(MDD) algorithm. By exploiting the inherent structural relationship between the 4-QAM signal's coordinates and 16-QAM signal's coordinates, another style of cost function for Modified Constant Modulus Algorithm(MCMA) is defined and If it happen to offset of received signals and MCMA is poor performance in order to overcome this because the paper combines apply for MCMA and MDD(Modified Decision Direct) algorithm. By computer simulation, we confirmed that the proposed PMCMA-MDD algorithm has the fater convergence rate and steady mean square error than the conventional MCMA.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.2 s.314
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• pp.39-45
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• 2007

This paper presents a novel scheme that quickly searches for the sweet spot of multiple array antennas, and locks on to it for high-speed millimeter wavelength transmissions, when communications to another antenna array are disconnected. The proposed method utilizes a modified genetic algorithm, which selects a superior initial group through preprocessing in order to solve the local solution in agenetic algorithm. TDD (Time Division Duplex) is utilized as the transfer method and data controller for the antenna. Once the initial communication is completed for the specific number of individuals, no longer antenna's data will be transmitted until each station processes GA in order to produce the next generation. After reproduction, individuals of the next generation become the data, and communication between each station is made again. Simulation results of 1:1, 1:2, 1:5 array antennas confirmed the efficiency of the proposed method. The 16bit split is 8bit, but it has similar performance as 16bit gene.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.561-566
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• 2021

The optimum kernel size for error-distribution estimation with given error samples cannot be used in the weight adjustment of minimum Euclidean distance between error distributions (MED) algorithms. In this paper, a new adaptive kernel estimation method for convergence enhancement of MED algorithms is proposed. The proposed method uses the average rate of change in error power with respect to a small interval of the kernel width for weight adjustment of the MED learning algorithm. The proposed kernel adjustment method is applied to experiments in communication channel compensation, and performance improvement is demonstrated. Unlike the conventional method yielding a very small kernel calculated through optimum estimation of error distribution, the proposed method converges to an appropriate kernel size for weight adjustment of the MED algorithm. The experimental results confirm that the proposed kernel estimation method for MED can be considered a method that can solve the sensitivity problem from choosing an appropriate kernel size for the MED algorithm.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.3
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• pp.183-190
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• 2019

This paper introduces a near-tip grid refinement and explores its usefulness in the crack analysis by the natural element method(NEM). As a sort of local h-refinement in finite element method(FEM), a NEM grid is locally refined around the crack tip showing high stress singularity. This local grid refinement is completed in two steps in which grid points are added and Delaunay triangles sharing the crack tip node are divided. A plane strain rectangular plate with symmetric edge cracks is simulated to validate the proposed local grid refinement and to examine its usefulness in the crack analysis. The crack analysis is also simulated using a uniform NEM grid for comparison. Unlike the uniform grid, the refined grid provides near-tip stress distributions similar to the analytic solutions and the fine grid. In addition, the refined grid shows higher convergence than the uniform grid, the global relative error to the total number of grid points.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.960-968
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• 1995

In this paper we present a reordering scheme that could lead to efficient vectorization of the preconditioners for the large sparse linear systems arising from partial differential equations on the CRAY-2, This reordering scheme is a line version of the conventional red/black ordering. This reordering scheme, coupled with a variant of ILU(Incomplete LU) preconditioning, can overcome the poor rate of convergence of the conventional red/black reordering, if relatively large number of fill-ins were used. We substantiate our claim by conducting various experiments on the CRAY-2 machine. Also, the computation of the Frobenius norm of the error matrices agree with our claim.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.226-230
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• 2006

홍수피해잠재능(Potential Flood Damage: PFD)은 면 개념을 도입함으로써 치수단위구역의 치수특성 및 사회경제적인 가치를 함께 평가할 수 있도록 고안된 지수로 이미 여러 유역에서 시행되고 있는 유역종합 치수계획 사업에서 사용되고 있으나, 몇 가지 중요한 문제점이 꾸준히 제기되어 왔다. 본 연구에서는 우선 다음과 같은 이론적 문제점을 검토하였다. PFD는 처음 제안될 당시 (이하 기존 PFD) '잠재성'과 '위험성'라는 두 가지 요소가 곱해지는(multiplicative) 형태로 구성된 후 '위험성' 요소 안에 '가능성'과 '방어능력'이 더해지는 (additive) 형태를 취하고 있었다. 그러나 본 연구에서는 (이하 수정 PFD) '피해대상', '피해가능성', 그리고 '방어취약성'이 모두 곱해져야 이론적으로 타당함을 제시하였다. 기존 PFD는 '방어취약성'이 0의 값, 즉 홍수에 대한 완전방어를 의미하는 값에 가까워져도 PFD 값이 0에 수렴하지 않는 반면, 수정 PFD는 위의 경우 홍수 피해잠재능이 0에 수렴하는 것을 요소별 시나리오 모의를 통해서 확인할 수 있었다. 두 번째로 본 연구에서는 PFD를 이용하여 유역의 목표치수안전도 설정 방안을 제시하였다. PFD의 물리적인 의미가 무차원화 된 피해량 임을 전제로, 피해대상으로부터 목표방어율을 설정한 후 이에 해당하는 목표방어취약성을 계산하는 절차를 전개하였다. 추후 이 방법을 실제 자료에 적용하여 검증하는 연구가 이어져야 할 것이다.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.58-67
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• 2000

The paper presents a representative-based feedback mechanism and rate adaptation policy for congestion control in multicast traffic for multimedia applications. In multicast congestion control, feedback implosion occurs as many receivers send feedback to a sender. We propose to use representatives to avoid the feedback implosion. In our scheme, receivers feedback packet loss information periodically and a sender adapts the sending rate based on the information collected through a hierarchy of representatives. A representative is selected in each region and roles as a filter to decrease the number of feedbacks. The simulation results show that the proposed scheme solves the feedback implosion problem and well adapts in a congested situation.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.1
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• pp.46-50
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• 2013

This paper proposes an adaptive fault accommodation control approach for flexible-joint (FJ) robots with multiple actuator faults. It is assumed that the value and occurrence time of multiple actuator faults are unknown. An adaptive fault accommodation control scheme with prescribed performance bounds, which characterize the convergence rate and maximum overshoot of tracking errors, is designed to accommodate the actuator faults. From the Lyapunov stability theorem, it is proved that all signals of the closed-loop system are semi-globally uniformly ultimately bounded and tracking errors are preserved within prescribed performance bounds regardless of actuator faults.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.35-46
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• 2000

In this paper, we propose a subband acoustic echo canceller using the weighted Overlap-add adaptive filter bank to prevent the decrease of convergence speed in full-band US processing, and make it possible to realize the adaptive filter in block-parallel processing, this paper introduces the weighted overlap-add technique for subband echo canceller. Moreover, we propose a new double-talk detector which employs dedicated filter in addition to the energy comparison method simultaneously. The computer simulation results show that the performance of the proposed subband adaptive echo canceller double-talk detection

• Nuclear industry
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• v.37 no.12
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• pp.5-19
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• 2017

산업통상자원부는 '17년부터 '31년까지 향후 15년간의 전력수급 전망 및 전력설비 계획 등을 담은 '제8차 전력수급기본계획'(안)을 마련하여 12월 14일 국회 산업통상자원중소벤처기업위원회(이하 산업위)의 통상 에너지 소위에 보고했다. 이번 계획(안)은 지난해 12월 계획 수립에 착수한 이래 약 1년간 70여명 전문가들의 43차례 회의를 거쳐 작성되었으며, 그간 수요 전망, 설비 계획, 예비율 등 5차례에 걸쳐 중간 결과를 공개하여 시민 환경단체, 에너지업계 등 이해 관계자로부터 의견을 수렴해 왔으며, 지난 9월에는 국회 산업위 통상에너지소위에 중간 보고를 하였다. 기존 수급계획이 수급 안정과 경제성 위주로 수립되었던 것에 반해, 이번 8차 계획은 최근 전기사업법 개정(전기사업법 제3조 개정('17.3월) : "전력수급기본계획 수립시, 전기설비의 경제성, 환경 및 국민안전에 미치는 영향 등을 종합적으로 고려하여야") 취지를 감안하여 환경성 안전성을 대폭 보강하여 수립한 것이 특징이다. 또한 발전소 건설을 우선 추진하기보다는 수요 관리를 통한 합리적 목표 수요 설정에 주안점을 두었고, 신규 발전설비는 대규모 원전 석탄 일변도에서 벗어나 친환경 분산형 재생에너지와 LNG 발전을 우선시하였다. 이번 수급계획은 국회 산업위 통상에너지소위 보고 외에도 국회 산업위 전체회의 보고, 공청회 등을 통해 추가적으로 의견을 수렴한 뒤 전력정책심의회 심의를 거쳐 최종 확정될 예정이다. 국회에 보고된 제8차 전력수급기본계획(안) 전문을 게재한다.