• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.7
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• pp.557-568
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• 1989

Using Power Spectrum Analysis, conditions of parameter convergence for a Model Reference Adaptive Control (MRAC) system are described. The general Persistent Excitation (PE) condition given in time domain can be transformed to the positiveness of auto-correlation matrix which is represented in frequency domain by the spectra of reference input signal. For an MRAC system designed with relative degree one, the existence and the uniqueness of parameter nominal values due to the variation of input spectra can be analyzed by the PE condition in frequency domain. If the input signal has 2n spectra or more, it can be shown that the nominal values exist independent of adaptive gain, input amplitudes, and magnitudes or numbers of their spectra.

• Coupled systems mechanics
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• v.1 no.1
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• pp.19-37
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• 2012

In this work, the iterative coupling of finite element and boundary element methods for the investigation of coupled fluid-fluid, solid-solid and fluid-solid wave propagation models is reviewed. In order to perform the coupling of the two numerical methods, a successive renewal of the variables on the common interface between the two sub-domains is performed through an iterative procedure until convergence is achieved. In the case of local nonlinearities within the finite element sub-domain, it is straightforward to perform the iterative coupling together with the iterations needed to solve the nonlinear system. In particular, a more efficient and stable performance of the coupling procedure is achieved by a special formulation that allows to use different time steps in each sub-domain. Optimized relaxation parameters are also considered in the analyses, in order to speed up and/or to ensure the convergence of the iterative process.

• Journal of the Institute of Convergence Signal Processing
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• v.18 no.2
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• pp.37-42
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• 2017

In this paper, we study on symbol error rate(SER) performance of frequency domain decision feedback equalization for modelled underwater channel. Underwater channel is generated by Bellhop model. Simulation results show that proposed method is efficient for underwater acoustic communication.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.133-142
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• 2014

The least mean square(LMS) algorithm has been popular owing to its simplicity, stability, and availability to implement. But it inherently has a problem of slow convergence speed, and the presence of a transfer function in the secondary path following the adaptive controller and the error path has been shown to generally degrade the stability and the performance of the LMS algorithm in applications of acoustical noise control. In general, in order to solve these problems, the filtered-x LMS (FX-LMS) type algorithms can be used and the bi-directional Filtered-x LMS(BFXLMS) algorithm is very attractive among them, which increase the convergence speed and the performance of the controller with nearly equivalent computation complexity. In this paper, a mathematical analysis for the BFXLMS algorithm is presented. In terms of view points of time domain, frequency domain, and stochastic domain, the characteristics and stabilities of algorithm is accurately analyzed.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.843-845
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• 2024

도메인 적응 사전 훈련(Domain-Adaptive Pre-training, DAPT)을 활용한 한국어 문서 요약 연구에서는 특정 도메인의 문서에 대한 이해도와 요약 성능을 향상시키기 위해 DAPT 기법을 적용했다. 이 연구는 사전 훈련된 언어 모델이 일반적인 언어 이해 능력을 넘어 특정 도메인에 최적화된 성능을 발휘할 수 있도록 도메인 특화 데이터셋을 사용하여 추가적인 사전 훈련을 진행한다. 구체적으로, 의료, 법률, 기술 등 다양한 도메인에서 수집한 한국어 텍스트 데이터를 이용하여 모델을 미세 조정하며, 이를 통해 얻은 모델은 도메인에 특화된 용어와 문맥을 효과적으로 처리할 수 있음을 보여준다. 성능 평가에서는 기존 사전 훈련 모델과 DAPT를 적용한 모델을 비교하여 DAPT의 효과를 검증했다. 연구 결과, DAPT를 적용한 모델은 도메인 특화 문서 요약 작업에서 성능 향상을 보였으며, 이는 실제 도메인별 활용에서도 유용할 것으로 기대된다.

• Journal of Convergence Society for SMB
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• v.6 no.4
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• pp.151-156
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• 2016

It has been constantly demanding for effective way to improve software development productivity and automation. In this paper, we did research to configure the component assets to reuse design information from the design phase domains based on the DMI. It is necessary abstracted information architecture of an independent platform development environment to reuse design information on the design stage. Also, It should be based on a well-designed to support the design architecture of the application domain. Therefore, in this paper, I want to use the DMI architecture that can be represented by formal level of architectural design information platform and application domain area. It is able to decomposition architecture asset with the part design information from the design phase composition or a high level of abstraction on DMI. Therefore, the metadata structure of the asset architecture will support a structure which can reuse the structure-based design of the domain areas.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.2
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• pp.13-19
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• 2001

The conventional fractal decoding was required a vast amount computational complexity, since every range blocks was implemented to IFS(iterated function system). In order to improve this, it has been suggested that each range block was classified to iterated and non-iterated regions. Non-iterated regions is called data dependency region, and if data dependency region extended, IFS regions are contractive. In this paper, a searched region of the domain is limited to the range regions that is similar with the domain blocks, and the domain region is more overlapped. As a result, data dependency region has maximum region, that is IFS regions can be minimum region. The minimizing method of domain region is defined to minimum domain(MD) which is minimum IFS region. Using the minimizing method of domain region, there is not influence PSNR(peak signal-to-noise ratio). And it can be performed a fast decoding by reducing the computational complexity for IFS in fractal image decoding.

• Convergence Security Journal
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• v.22 no.4
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• pp.169-178
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• 2022

In general, organizations operating multi-domain networks find it difficult to represent and manage multiple domain net works on a single screen space. Instead, most of them are managed with multiple screens visualizing network topology by domain or partitioning one screen area into multiple domains. We propose an efficient method to visualize the topology using only minimal connection information between domain-agnostic nodes in this work. This method visualizes the topology by utilizing centrality indices representing the influence of nodes in the network. Furthermore, the method dynamically segments the entire node's display area using virtual Root nodes to auto-separate domains and weights of child nodes and placing nodes in 3D space. Thus, although it is a straightforward method, the multi-domain network topology can be visualized with only minimal connection information between nodes.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.644-646
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• 1998

The main drawback of filtered-X LMS(FXLMS) algorithm for the ANC of broadband noises is its low convergence speed when the filtered reference signals are strongly correlated, producing a large eigenvalue spread in correlation matrix. This correlation can be caused either by autocorrelation of the signals of the reference sensors, or by coupling between the error path which introduces intercorrelation in the filtered reference signals. In this paper, we introduce a transform domain FXLMS(TD-FXLMS) algorithm that has a high convergence speed by orthogonal transform's decorrelation properties.

• ETRI Journal
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• v.34 no.3
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• pp.474-477
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• 2012

The MPEG-D unified speech and audio coding (USAC) standardization process was initiated by MPEG to develop an audio codec that is able to provide consistent quality for mixed speech and music contents. The current USAC reference model structure consists of frequency domain (FD) and linear prediction domain (LPD) core modules and is controlled using a signal classifier tool. In this letter, we propose an LPD single-mode USAC structure using an adaptive widowing-based transform-coded excitation module. We tested our system using official test items for all mono-evaluation modes. The results of the experiment show that the objective and subjective performances of the proposed single-mode USAC system are better than those of the FD/LPD dual-mode USAC system.