• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.321-327
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• 2004

SPIHT algorithm is a wavelet based fast and effective technique for image compression. It uses a list structure to store status information which is generated during set-partitioning of toro-tree. Usually, this requires lots of additional memory depending on how high the bit-rate is. Therefore, in this paper, we propose a new technique called MZC-BFS, which needs no additional memory when running SPIHT algorithm. It explicitly performs a breadth first search of the spatial-tree using peano-code and eliminates additional memory as it uses pre-status significant test for encoding and LSB bits of some coefficients for decoding respectively. This method yields nearly the same performance as SPIHT. This may be desirable in fast and simple hardware implementation and reduces the cost of production because no lists and additional memory are required.

• Korean Journal of Remote Sensing
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• v.1 no.1
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• pp.5-27
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• 1985

A hill-sliding technique was devised to extract Gaussian clusters from the multivariate probability density estimates of sample data for the first step of iterative unsupervised classification. The underlying assumption in this approach was that each cluster possessed a unimodal normal distribution. The key idea was that a clustering function proposed could distinguish elements of a cluster under formation from the rest in the feature space. Initial clusters were extracted one by one according to the hill-sliding tactics. A dimensionless cluster compactness parameter was proposed as a universal measure of cluster goodness and used satisfactorily in test runs with Landsat multispectral scanner (MSS) data. The normalized divergence, defined by the cluster divergence divided by the entropy of the entire sample data, was utilized as a general separability measure between clusters. An overall clustering objective function was set forth in terms of cluster covariance matrices, from which the cluster compactness measure could be deduced. Minimal improvement of initial data partitioning was evaluated by this objective function in eliminating scattered sparse data points. The hill-sliding clustering technique developed herein has the potential applicability to decomposition of any multivariate mixture distribution into a number of unimodal distributions when an appropriate diatribution function to the data set is employed.

• Smart Structures and Systems
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• v.20 no.1
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• pp.61-74
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• 2017

One of the most reliable and simplest tools for structural vibration control in civil engineering is Tuned Mass Damper, TMD. Provided that the frequency and damping parameters of these dampers are tuned appropriately, they can reduce the vibrations of the structure through their generated inertia forces, as they vibrate continuously. To achieve the optimal parameters of TMD, many different methods have been provided so far. In old approaches, some formulas have been offered based on simplifying models and their applied loadings while novel procedures need to model structures completely in order to obtain TMD parameters. In this paper, with regard to the nonlinear decision-making of fuzzy systems and their enough ability to cope with different unreliability, a method is proposed. Furthermore, by taking advantage of both old and new methods a fuzzy system is designed to be operational and reduce uncertainties related to models and applied loads. To design fuzzy system, it is required to gain data on structures and optimum parameters of TMDs corresponding to these structures. This information is obtained through modeling MDOF systems with various numbers of stories subjected to far and near field earthquakes. The design of the fuzzy systems is performed by three methods: look-up table, the data space grid-partitioning, and clustering. After that, rule weights of Mamdani fuzzy system using the look-up table are optimized through genetic algorithm and rule weights of Sugeno fuzzy system designed based on grid-partitioning methods and clustering data are optimized through ANFIS (Adaptive Neuro-Fuzzy Inference System). By comparing these methods, it is observed that the fuzzy system technique based on data clustering has an efficient function to predict the optimal parameters of TMDs. In this method, average of errors in estimating frequency and damping ratio is close to zero. Also, standard deviation of frequency errors and damping ratio errors decrease by 78% and 4.1% respectively in comparison with the look-up table method. While, this reductions compared to the grid partitioning method are 2.2% and 1.8% respectively. In this research, TMD parameters are estimated for a 15-degree of freedom structure based on designed fuzzy system and are compared to parameters obtained from the genetic algorithm and empirical relations. The progress up to 1.9% and 2% under far-field earthquakes and 0.4% and 2.2% under near-field earthquakes is obtained in decreasing respectively roof maximum displacement and its RMS ratio through fuzzy system method compared to those obtained by empirical relations.

• The Transactions of the Korea Information Processing Society
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• v.6 no.6
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• pp.1656-1666
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• 1999

The more complex and large digital circuits become, the more important delay test becomes which guarantees that circuits operate in time. In this paper, the proposed algorithm is developed, which enable the fast indirect implication for efficient test pattern generation in sequential circuits of standard scan environment. Static learning algorithm enables application of a new implication value using contrapositive proposition. The static learning procedure found structurally, analyzes the gate structure in the preprocessing phase and store the information of learning occurrence so that it can be used in the test pattern generation procedure if it satisfies the implication condition. If there exists a signal line which include all paths from some particular primary inputs, it is a partitioning point. If paths passing that point have the same partial path from primary input to the signal or from the signal to primary output, they will need the same primary input values which separated by the partitioning point. In this paper test pattern generation can be more effective by using this partitioning technique. Finally, an efficient delay fault test pattern generator using indirect implication is developed and the effectiveness of these algorithms is demonstrated by experiments.

• Journal of the military operations research society of Korea
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• v.6 no.2
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• pp.89-127
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• 1980

The multivariate analysis techniques of cluster analysis are examined in this article. The theory and applications of the techniques and computer software concerning these techniques are discussed and sample jobs are included. A hierarchical cluster analysis algorithm, available in the IMSL software package, is applied to a set of data extracted from a group of subjects for the purpose of partitioning a collection of 26 attributes of a weapon system into six clusters of superattributes. A nonhierarchical clustering procedure were applied to a collection of data of tanks considering of twenty-four observations of ten attributes of tanks. The cluster analysis shows that the tanks cluster somewhat naturally by nationality. The principal componant analysis and the discriminant analysis show that tank weight is the single most important discriminator among nationality although they are not shown in this article because of the space restriction. This is a part of thesis for master's degree in operations research.

• Journal of Industrial Technology
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• v.17
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• pp.323-330
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• 1997

In this paper, a new approach to modeling of nonlinear systems using fuzzy theory is presented. To express the various and complex behavior of nonlinear system, we combine multiple model method with hierachical prioritized structure, and the mountain clustering technique is used in partitioning of system. TSK rule structure is adopted to form the fuzzy rules, and Back propagation algorithm is used for learning parameters in consequent parts of the rules. Also we soften the paradigm of Mamdani's inference mechanism by using Yager's S-OWA operators. Computer simulations are performed to verify the effectiveness of the proposed method.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.244-246
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• 2002

클러스터 기반의 VOD 서버는 동시에 여러 사용자에게 실시간으로 고품질 서비스를 위해 정교한 부하 분산 기술과 버퍼관리 기술을 요구한다. 본 논문은 클러스터 기반 VOD 서버에서 동적 버퍼 분할을 이용한 새로운 부하분산 기법을 제안한다. 제안된 기법은 사용자 요청을 처리하는 서비스 노드간의 버퍼 성능과 디스크 접근 빈도를 고려하여 노드 부하를 고르게 분산한다. 또한 동적 버퍼 분할 기법은 동일한 연속 매체에 접근하려는 여러 사용자에게 평균 대기시간을 감소시킬 수 있도록 버퍼를 동적으로 분할한다. 각 서비스 노드에서 동적 버퍼 분할로 발생하는 버퍼 정보를 유지함으로써 각 서비스 노드의 버퍼 재사용을 극대화할 수 있다. 시뮬레이션을 통해 제안된 기법이 효율적인 버퍼 관리로 노드 부하 균등화, 사용자 평균 대기시간 감소, 병행 사용자 수 증가 등의 성능 향상을 얻었다.

• Journal of the Korean Professional Engineers Association
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• v.20 no.1
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• pp.14-20
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• 1987

The development of the FHT (fast Hadamard transform) was presented and based on the derivation by Cooley-Tukey algorithm. Alternately, it can be derived by matrix partitioning or matrix factorization techniques. This paper proposes a simple sparse matrix technique by Kronecker product of successive lower Hadamard matrix. The following shows how the Kronecker product can be mathematically defined and efficiently implemented using a matrix factorization methods.

• Annual Conference of KIPS
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• 2001.10b
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• pp.1607-1610
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• 2001

회로분할 기법은 VLSI 칩 설계 시 핵심적인 기술로서 오랫동안 연구가 행해져 왔는데, 대부분의 회로분할 휴리스틱에서 Fiduccia-Mattheyses(FM) 알고리즘을 기본 기술로 사용하고 있다. 본 논문에서도 FM 알고리즘을 기본 분한 기술로 이용하되 선형배치 및 클러스터링 기법을 추가로 적용하여 효과적인 회로 분할 알고리즘을 제안한다. MCNC 벤치마크 회로를 이용하여 제안한 알고리즘과 FM 알고리즘을 실험적으로 비교하였다. 실험결과는 회로에 따라 적게는 14%, 많게는 57%까지 개선되는 것을 보여준다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.237-240
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• 2001

이질적인 환경인 인터넷을 통한 멀티미디어 서비스가 확산됨에 따라 다량의 데이터를 가지는 비디오 스트림의 전송이 늘어나게 되었다. 이로 인해 네트워크 트래픽의 대부분을 멀티미디어 데이터가 차지하게 되었다. 한정된 통신망 자원을 효율적으로 사용하기 위하여 사용자의 컴퓨터 환경이나 통신망 환경을 고려하여 비디오 데이터를 전송함으로서 자원의 낭비를 막고자 계층적 코딩에 관한 연구가 시도되었다. 본 논문에서는 네트워크와 사용자의 환경을 고려하여 MPEG 비디오 데이터를 전송할 수 있도록 하기 위하여 TMS(Temoral and Motion Scaling)기법을 제안한다. TMS기법은 시간 계층적 코딩과 모션벡터를 이용한 데이터 분할 계층적 코딩 방법을 사용하여 비디오 데이터를 분할한다. 본 논문에서 제안하는 기법을 사용하여 MPEG 비디오 데이터를 전송할 때 기존의 제안된 기법들에 대해 적은 데이터로 고화질의 영상을 전송함으로서 효율적으로 통신망 자원을 사용할 수 있게 된다.