• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.907-916
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• 2019

In this paper, we propose a new five-qubit multiple bit flip code that can completely protect the target qubit from all multiple bit flip errors using only CNOT gates. The proposed multiple bit flip codes can be easily extended to multiple phase flip codes by embedding Hadamard gate pairs in the root error section as in conventional single bit flip code. The multiple bit flip code and multiple phase flip code in this paper share the state vector error information by four auxiliary qubits. These four-qubit state vectors reflect the characteristic that all the multiple flip errors with Pauli X and Z corrections commonly include a specific root error. Using this feature, this paper shows that low-cost implementation is possible despite the QECC design for multiple-flip error correction by batch processing the detection and correction of Pauli X and Z root errors with only three CNOT gates. The five-qubit multiple bit flip code and multiple phase flip code proposed in this paper have 100% error correction rate and 50% error discrimination rate. All QECCs presented in this paper were verified using QCAD simulator.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.532-532
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• 2006

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.29-37
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• 2000

Asynchronous transfer mode is flexible to support multimedia communication services using asynchronous time-sharing and statistical multimedia techniques to the existing data communication area, ATM ABR service controls network traffic using feedback information on the network congestion situation in order to guarantee the demanded service qualities and the available cell rates, In this paper we apply the control method using queue length prediction to the formation of feedback information for more efficient ABR traffic control. If backward node receive the longer delayed feedback information on the impending congestion, the switch can be already congested from the uncontrolled arriving traffic and the fluctuation of queue length can be inefficiently high in the continuing time intervals, The feedback control method proposed in this paper predicts the queue length in the switch using the slope of queue length prediction function and queue length changes in time-series, The predicted congestion information is backward to the node, NLMS and neural network are used as the predictive control functions, and they are compared from performance on the queue length prediction. Simulation results show the efficiency of the proposed method compared to the feedback control method without the prediction, Therefore, we conclude that the efficient congestion and stability of the queue length controls are possible using the prediction scheme that can resolve the problems caused from the longer delays of the feedback information.

• Journal of KIISE:Databases
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• v.33 no.2
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• pp.175-187
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• 2006

The data cube is an aggregation operator that computes group-bys for all possible combination of dimension attributes. %on the number of the dimension attributes is n, a data cube computes $2^n$ group-bys. Each group-by in a data cube is called a cuboid. Data cubes are often precomputed and stored as materialized views in data warehouses. These data cubes need to be updated when source relation change. The incremental maintenance of a data cube is to compute and propagate only its changes. To compute the change of a data cube of $2^n$ cuboids, previous works compute a delta cube that has the same number of cuboids as the original data cube. Thus, as the number of dimension attributes increases, the cost of computing a delta cube increases significantly. Each cuboid in a delta cube is called a delta cuboid. In this paper. we propose an incremental cube maintenance method that can maintain a data cube by using only $_nC_{{\lceil}n/2{\rceil}}$ delta cuboids. As a result, the cost of computing a delta cube is substantially reduced. Through various experiments, we show the performance advantages of our method over previous methods.

• Journal of Convergence for Information Technology
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• v.7 no.2
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• pp.43-51
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• 2017

Background/Objectives : The purpose of this study is to propose a multi-threaded web crawl using queues that can solve the problem of time delay of single processing method, cost increase of parallel processing method, and waste of manpower by utilizing multiple bots connected by wide area network Design and implement. Methods/Statistical analysis : This study designs and analyzes applications that run on independent systems based on multi-threaded system configuration using queues. Findings : We propose a multi-threaded web crawler design using queues. In addition, the throughput of web documents can be analyzed by dividing by client and thread according to the formula, and the efficiency and the number of optimal clients can be confirmed by checking efficiency of each thread. The proposed system is based on distributed processing. Clients in each independent environment provide fast and reliable web documents using queues and threads. Application/Improvements : There is a need for a system that quickly and efficiently navigates and collects various web sites by applying queues and multiple threads to a general purpose web crawler, rather than a web crawler design that targets a particular site.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.2
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• pp.55-60
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• 2008

Packet-switched wavelength division multiplexing (WDM) ring networks have been extensively studied as solutions to the increasing amount of traffic in metropolitan area networks, which is widely expected to be a mix of unicast and multicast traffic. In this paper we study the fairness between unicasting and multicasting in slotted packet-switched WDM ring networks that employ a tunable transmitter and fixed tuned receiver at each node and a posteriori buffer selection. We find that single-step longest queue selection algorithm generally results in unfairness between unicasting and multicasting or a lilted relative priority for multicast vs. unicast traffic. We present the various virtual output queue structures and their performance.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.511-512
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• 2008

EPLA 패킷 스케줄링 알고리즘은 IEEE 802.22 WRAN 시스템의 실시간 트래픽 전송 지원을 위한 패킷 스케줄링 알고리즘으로 참고문헌[4]으로 제안되었다. 패킷 기반 무선 전송 시스템에서 실시간 트래픽의 경우 짧은 데이터 유효 시간을 가지며, 만약 데이터 유효 시간이 초과할 경우 실시간 트래픽 데이터로써의 가치를 상실하기 때문에 시스템에서는 해당패킷을 전송하지 않고 제거해 버린다. 그러므로 실시간 트래픽의 중요한 서비스 품질(QoS) 인자인 요구된 패킷 손실율을 보장하기 위해서는 실시간 트래픽의 데이터 유효 시간을 고려하여 자원을 할당하여야 한다. 기존의 패킷 스케쥴링 알고리즘들은 많은 경우 큐의 맨 앞에 위치한 패킷의 지연 시간을 고려하지만 EPLA는 패킷이 저장되는 큐 내의 다음 프레임에서 제거 될 것으로 예상되는패킷의 손실양을 고려하여 자인을 할당함으로 기존의 실시간 패킷 스케줄링 알고리즘에 비해 훨씬 좋은 성능을 보인다. 하지만 EPLA는 예상되는 패킷 손실양을 계간하기 위해서 모든 사용자의 큐에 저장된 패킷들을 확인해야하므로 높은 복잡도를 가지는 문제점이 있다. 본 논문에서는 각 사용자로부터 피드백 받은 부채널의 상태 정보를 기반으로 사용자 큐를 확인하여 횟수를 제한함으로써 패킷 손실을 성능의 손실 없이 복잡도를 줄이는 간단한 방법을 제안하고, 실시간 트래픽인 음성 트래픽과 비디오 트래픽에 대한 시뮬레이션 결과를 통해 이를 확인한다.

• The KIPS Transactions:PartA
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• v.17A no.4
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• pp.167-172
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• 2010

This paper proposes a set of runtime test models for priority queues and shows the runtime test results based on the proposed test models for the representative priority queues: the traditional heap, post-order heap, and pairing heap. Among these heaps, the traditional heap is the worst in time complexity analyzed. But, according to our experimental results based on the test models proposed, it is shown that the slowest one is the pairing heap that utilizes pointers and the fastest one is the traditional heap. For the two implicit heaps, these results are in contrary to the fact that the post-order heap is better than the traditional heap in time complexity analyzed.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.613-624
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• 2003

This paper proposes a design for efficient and accurate retrieval of similar image subsequences using the multi-dimensional time warping distance as similarity evaluation tool in image sequence database after building of two indexing structures implemented with priority queue and suffix tree respectively. Receiving query image sequence, at first step, the proposed method searches the candidate set of similar image subsequences in priory queue index structure. If it can not get satisfied results, it retrieves another candidate set in suffix tree index structure at second step. The using of the low-bound distance function can remove the dissimilar subsequence without false dismissals during similarity evaluating process between query image sequence and stored sequences in two index structures.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.177-183
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• 2007

Active queue management (AQM) refers to a family of packet dropping mechanisms for router queues that has been proposed to support end-to-end congestion control mechanisms in the Internet. The proposed AQM algorithm by the IETF is Random Early Detection (RED). The RED algorithm allows network operators simultaneously to achieve high throughput and low average delay. However. the resulting average queue length is quite sensitive to the level of congestion. In this paper, we propose the Refined Adaptive RED(RARED), as a solution for reducing the sensitivity to parameters that affect RED performance. Based on simulations, we observe that the RARED scheme improves overall performance of the network. In particular, the RARED scheme reduces packet drop rate and improves goodput.