• Communications for Statistical Applications and Methods
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• 제27권4호
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• pp.431-443
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• 2020

The K-means clustering algorithm has had successful application in sufficient dimension reduction. Unfortunately, the algorithm does have reproducibility and nestness, which will be discussed in this paper. These are clear deficits for the K-means clustering algorithm; however, the hierarchical clustering algorithm has both reproducibility and nestness, but intensive comparison between K-means and hierarchical clustering algorithm has not yet been done in a sufficient dimension reduction context. In this paper, we rigorously study the two clustering algorithms for two popular sufficient dimension reduction methodology of inverse mean and clustering mean methods throughout intensive numerical studies. Simulation studies and two real data examples confirm that the use of hierarchical clustering algorithm has a potential advantage over the K-means algorithm.

• 응용통계연구
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• 제34권6호
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• pp.969-977
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• 2021

본 연구에서는 Hierarchical K-means 군집화 알고리즘을 이용해 서울의 A아파트 가구들의 전력 사용량 패턴을 군집화 하였다. 차원을 축소해주면서 패턴을 파악할 수 있는 Hierarchical K-means 군집화 알고리즘은 기존 K-means 군집화 알고리즘의 단점을 보완하여 최근 대용량 전력 사용량 데이터에 적용되고 있는 방법론이다. 본 연구에서는 여름 저녁 피크 시간대의 시간당 전력소비량 자료에 대해 군집화 알고리즘을 적용하였으며, 다양한 군집 개수와 level에 따라 얻어진 결과를 비교하였다. 결과를 통해 사용량에 따라 패턴이 군집화 됨을 확인하였으며, 군집화 유효성 지수들을 통해 이를 비교하였다.

• 전자공학회논문지B
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• 제28B권11호
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• pp.913-924
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• 1991

In this paper, we propose a motion estimation algorithm using hierarchical structure. The algorithm uses the image pyramids from the repetitive application of Gaussian filtering and decimation, and performs an inter-level displacement propagation in its motion estimation process. The motion estimation algorithm based on the hierarchical structure is shown to be very effective since this scheme utilizes the local imformation as well as the global imformation. The experimental results on the various data imdicate that compared to the Horn and Schunck's method, the proposed algorithm yields an accurate motion estimation with a fast convergence behaviour.

• Journal of Communications and Networks
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• 제4권3호
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• pp.209-220
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• 2002

In this paper, we propose a hierarchical packet scheduling technique to closely approximate a hierarchical extension of the generalized processor sharing model, Hierarchical Generalized Processor Sharing (H-GPS). Our approach is to undertake the tasks of service guarantee and hierarchical link sharing in an independent manner so that each task best serves its own objective. The H-GPS model is decomposed into two separate service components: the guaranteed service component to consistently provide performance guarantees over the entire system, and the excess service component to fairly distribute spare bandwidth according to the hierarchical scheduling rule. For tight and harmonized integration of the two service components into a single packet scheduling algorithm, we introduce two novel concepts of distributed virtual time and service credit, and develop a packet version of H-GPS called Hierarchical Fair Queueing (HFQ). We demonstrate the layerindependent performance of the HFQ algorithm through simulation results.

• ETRI Journal
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• 제42권6호
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• pp.922-931
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• 2020

A hierarchical iterative algorithm for the canonical polyadic decomposition (CPD) of tensors is proposed by improving the traditional conjugate gradient least squares (CGLS) method. Methods based on algebraic operations are investigated with the objective of estimating the direction of arrival (DoA) and polarization parameters of signals impinging on an array with electromagnetic (EM) vector-sensors. The proposed algorithm adopts a hierarchical iterative strategy, which enables the algorithm to obtain a fast recovery for the highly collinear factor matrix. Moreover, considering the same accuracy threshold, the proposed algorithm can achieve faster convergence compared with the alternating least squares (ALS) algorithm wherein the highly collinear factor matrix is absent. The results reveal that the proposed algorithm can achieve better performance under the condition of fewer snapshots, compared with the ALS-based algorithm and the algorithm based on generalized eigenvalue decomposition (GEVD). Furthermore, with regard to an array with a small number of sensors, the observed advantage in estimating the DoA and polarization parameters of the signal is notable.

• 대한전자공학회논문지
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• 제25권8호
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• pp.998-1009
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• 1988

A Hierarchical Circuit Extract Algotithm, which efficiently extract circuits from VLSI mask pattern information, is programmed. Quad-tree is used as a data structure which includes various CIF circuit elements and instances. This system is composed of CIF input routine, Quad-tree making routine, Transistor finding routine and Connection list making routine. This circuit extractor can extract circuit with hierarchical structure of circuit. This system is designed using YACC and LEX. By programming this algorithm with C language and adopting to various circuits, the effectiveness of this algorithm is showed.

• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.899-905
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• 2003

An intermediate images generation method using multi-resolution based hierarchical block matching disparity map is proposed. This method is composed of a disparity estimation, an occlusion detection and intermediate image synthesis. For the disparity estimation, which is one of the important processes in intermediate image synthesis, we use the multi-resolution based hierarchical block matching algorithm to overcome the imperfect ness of block matching algorithm. The proposed method makes disparity maps more accurate and dense by multi-resolution based hierarchical block matching, and the estimated disparity maps are used to generate intermediate images of stereo images. Generated intermediate images show 0.1∼1.4 ㏈ higher PSNR than the images obtained by block matching algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.621-622
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• 2008

When exchanging user data between nodes in a hierarchical conference system using the endpoint mixing scheme, the hierarchical structure may cause extra delay. The algorithm[1] was proposed for minimizing the media delay between the number of the neighboring nodes. In this paper, we implement a hierarchical conference with SIP protocol based on the algorithm.

• 한국컴퓨터정보학회논문지
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• 제21권2호
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• pp.51-60
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• 2016

This paper proposes a hierarchical routing algorithm for enhancing survivability of sensor nodes on WSAN. Proposed algorithm has two important parts. The first is a clustering algorithm that uses distance between sensor and actor, and remaining energy of sensor nodes for selecting cluster head. It will induce uniform energy consumption, and this has a beneficial effect on network lifetime. The second is an enhanced routing algorithm that uses the shortest path tree. The energy efficient routing is very important in WSAN which has energy limitation. As a result, proposed algorithm extends network and nodes lifetime through consuming energy efficiently. Simulation results show that the proposed clustering algorithm outperforms conventional routing algorithms such as VDSPT in terms of node and network life time, delay, fairness, and data transmission ratio to BS.

• 대한전자공학회논문지SP
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• 제44권5호
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• pp.54-63
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• 2007

본 논문은 영상 완성(image completion)을 위해 계층적으로 적용되는 새로운 에너지 최적화 방식을 제안한다. 영상 완성의 목적은 영상의 특정 영역이 지워진 상태에서, 그 지워진 부분을 나머지 부분과 시각적으로 어울리도록 완성시키는 기법을 말한다. 본 논문에서는 전역적 특징의 탐지, 주변 환경 변화에 대한 유연성, 계산비용의 감소, 영상 인페인팅과 같은 관련기법들로의 확장성 문제들을 다룰 수 있도록 마르코프 랜덤 필드(Markov Random Field)로 모델링 된 예제 기반 방식(exampler-based mehtod) 접근법을 택한다. 그리고 MRF에서의 에너지 최적화를 위해 BP 알고리즘(Belief Propagation Algorithm)의 변형인 우선순위 BP 알고리즘(Priority-Belief Propagation Algorithm)을 적용하였다. 본 논문에서 제안한 계층적 우선순위 BP 알고리즘(Hierarchical Priority-Belief Propagation Algorithm)은 MRF의 정점의 수를 줄이고 메시지를 계층적으로 전파한다. 이렇게 계층적 우선순위 BP 알고리즘을 영상 완성에 적용하여 여러 영상들에서 바람직한 결과를 얻었다.