• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.42-48
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• 2002

Placement is an important step in the physical design of VLSI circuits. It is the problem of placing a set of circuit modules on a chip to optimize the circuit performance. The most popular algorithms for placement include the cluster growth, simulated annealing and integer linear programming. In this paper we propose a genetic algorithm searching solution space for the placement problem, and then compare it with simulated annealing by analyzing the results of each implementation.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.500-505
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• 1996

고온의 정상상태에서 조사된 후 재조직(restructuring)과 균열(cracking)이 일어난 핵연료 내에서 결정립 외부 공극의 을 결정할 수 있는 퍼콜레이션(Percolation) 모델을 개발하였다. 핵연료 펠렛은 다수의 작은 정육각형 결정립들로 구성된 큰 정육각형으로 모의한다. 핵연료봉은 형상과 열적 특성이 다른 네 개의 영역으로 구분하고 각 경계 위치를 임계온도로부터 계산한다. 공극의 상호연결분율은, 몬테카를로 방법으로써 싸이트(Site)의 채워짐 여부를 점검하고 Hoshen-Kopelman 방법으로써 자유 공간에 연결된 클러스터(Cluster)에 포함된 싸이트들의 수를 계산하여 채워진 싸이트의 총 개수에 대한 연결 싸이트들의 개수의 비로써 구한다. AECL-2230, CBX 핵연료봉 실험의 기체 방출분율 자료에 대하여, FASTGRASS 코드의 상호연결분율 함수를 영역별로 계산한 상호연결분율로 대치하여 계산한 결과와 비교하였다. 균열과 재조직은 핵분열 기체 방출에 상당히 영향을 미치는 것으로 나타났다. 이 모델의 주요 장점은 결정립계에서의 상호연결현상을 단순 상호연결분율보다 좀더 사실적으로 모의하며 결정립의 성장과 균열을 고려할 수 있다는 점이다.

• Annual Conference of KIPS
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• 2012.04a
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• pp.612-614
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• 2012

센서 네트워크는 센싱 기능과 데이터 처리 그리고 무선 통신기능을 갖춘 많은 노드로 이루어져 있다. 센서 노드는 제한적인 CPU, 배터리 그리고 저장공간과 같은 제약사항을 가지고 있기 때문에 시간이 지날수록 노드의 수명이 다해 전체 적인 네트워크의 성능은 감소하게 된다. 본 논문에서는 이기종 센서 네트워크에서 노드 개수에 따른 작업 수행 시간의 분석을 통해 센서 네트워크의 수명을 판단한다. 성능 평가 결과 계층 기반의 라우팅 기법의 경우 클러스터 수의 비율이 네트워크의 수명에 큰 영향올 주는 것을 알 수 있다.

• Annual Conference of KIPS
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• 2008.05a
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• pp.648-650
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• 2008

스트리밍 서비스를 위한 서버 시스템은 실시간 데이터를 서비스하기 위한 충분한 용량을 가져야 하며 많은 클라이언트들에게 비디오 파일을 전송할 수 있어야 한다. 또한 지속적으로 늘어나는 사용자수와 추가되는 새로운 저장 공간에 대한 우수한 확장성을 제공하여야 한다. 그러나 현재의 범용 스트리밍 서버시스템은 이러한 요구사항을 충분히 반영하지 못할 뿐만 아니라 늘어나는 사용자의 부하와 시스템 요구에 대한 확장성 및 고화질 고용량의 미디어 데이터에 대한 반영이 이루어지지 못하여 점차 증가되는 사용자의 서비스 요구에 대한 사항을 충족시키지 못하고 있다. 본 논문에서는 이러한 사용자의 요구에 대하여 효과적인 QoS와 효율적인 Management 정책을 제시하고 이에 따라 개발된 우수한 병렬 미디어 스트리밍 서버(PMSS)를 소개한다.

• Journal of the Korea Society of Computer and Information
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• v.19 no.10
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• pp.1-12
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• 2014

This paper implements and improves the performance of high computational subtractive clustering algorithm using a single instruction, multiple data (SIMD) based many-core processor. In addition, this paper implements five different processing element (PE) architectures (PEs=16, 64, 256, 1,024, 4,096) to select an optimal PE architecture for the subtractive clustering algorithm by estimating execution time and energy efficiency. Experimental results using two different medical images and three different resolutions ($128{\times}128$, $256{\times}256$, $512{\times}512$) show that PEs=4,096 achieves the highest performance and energy efficiency for all the cases.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.6
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• pp.491-499
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• 2001

In this paper, the scheme of an efficient fuzzy rule generation and fuzzy system construction using GA(genetic algorithm) and FCM(fuzzy c-means) clustering algorithm is proposed for TSK(Takagi-Sugeno-Kang) type fuzzy system. In the structure identification, input data is transformed by PCA(Principal Component Analysis) to reduce the correlation among input data components. And then, a set fuzzy rules are generated for a given criterion by FCM clustering algorithm . In the parameter identification premise parameters are optimally searched by GA. On the other hand, the consequent parameters are estimated by RLSE(Recursive Least Square Estimate) to reduce the search space. From this one can systematically obtain the valid number of fuzzy rules which shows satisfying performance for the given problem. Finally, we applied the proposed method to the Box-Jenkins data and rice taste data modeling problems and obtained a better performance than previous works.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.527-535
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• 2003

In this paper, the performance of W-CDMA system with smart antenna is analyzed for angular spread in realistic wideband multipath channel. The realistic wideband channel is assumed, one of which is JTC channel model. And each multipath is assumed as a reflective wave from only one direction (only one cluster) in space. Several multipaths within one chip are distinguished into each one and the strongest signal is selected. As a result, the performance of the W-CDMA system with smart antenna in realistic wideband multipath channel has been considerably improved in proportion to the increase of angular spread.

• Journal of the Economic Geographical Society of Korea
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• v.19 no.3
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• pp.437-456
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• 2016

The purpose of this study is to understand the locational characteristics of performing art industries and to investigate the linkages with local economy. For the purpose, we examine the spatial concentration of cultural and artistic resources in Korea first, and than focus on Seoul where the resources of performing art industries are concentrated to the utmost. To distinguish the distribution aspect and locational characteristics of performing art industries, we apply the Kernel density analysis and LISA (Local Indicator of Spatial Association) on the address data of performing art theater, gallery, and movie theater. In contrast to galleries and movie theaters. the spatial distribution pattern of performing art theaters reveals a unique local cluster centered on the Daehakro area. We confirm that the Daehakro area constitutes a performing art industry cluster in their dense distribution of various related activities making up the value chain of the performing art industry. Multiple regression analysis probes the related economic activities to explain the distribution of performing art theaters as well as the linkages with the local economic landscape.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1155-1160
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• 2013

The rapid growth of smart phones has made location-based services (LBSs) widely available. However, the use of LBS can raise privacy issues, as LBS can allow adversaries to violate the location privacy of users. There has been a considerable amount of research on preserving user location privacy. Most of these studies try to preserve location privacy by achieving what is known as location K-anonymity. In this paper, we propose a hierarchical clustering-based spatial cloaking algorithm for LBSs. The proposed algorithm constructs a tree using a modified version of agglomerative hierarchical clustering. The experimental results show, in terms of the ASR size, that the proposed algorithm is better than Hilbert Cloak and comparable to RC-AR (R-tree Cloak implementation of Reciprocal with an Asymmetric R-tree split). In terms of the ASR generation time, the proposed algorithm is much better in its performance than RC-AR and similar in performance to Hilbert Cloak.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.657-668
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• 2008

Traditional off-the-shelf file server has several potential drawbacks to store data blocks. A first drawback is a lack of practical de-duplication consideration for storing data blocks, which leads to worse storage capacity waste. Second drawback is the requirement for high performance computer system for processing large data blocks. To address these problems, this paper proposes a clustering backup system that exploits file fingerprinting mechanism for block-level de-duplication. Our approach differs from the traditional file server systems in two ways. First, we avoid the data redundancy by multi-level file fingerprints technology which enables us to use storage capacity efficiently. Second, we applied a cluster technology to I/O subsystem, which effectively reduces data I/O time and network bandwidth usage. Experimental results show that the requirement for storage capacity and the I/O performance is noticeably improved.