• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.78-81
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• 2010

In this paper, we propose an efficient and effective selective protection scheme to SVC that exploit the propagation of protection effect by protecting significant frames that can give the maximum visual quality degradation. We model SVC dependency coding structure as a directed acyclic graph which is characterized with an estimated visual quality value as the attribute at each node. The estimated visual quality is calculated by using our model based on the proportions of intra- and inter-predicted MBs, amounts of residual, and estimated visual quality of reference frames. The proposed selective protection scheme traverses the graph to find optimal protection paths that can give maximum visual quality degradation. Experimental results show that the proposed selective protection scheme reduces the required number of frames to be protected by 46.02% compared to the whole protection scheme and 27.56% compared to the layered protection scheme.

• Molecular & Cellular Toxicology
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• v.1 no.4
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• pp.281-283
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• 2005

Extraction of biologically meaningful data and their validation are very important for toxicogenomics study because it deals with huge amount of heterogeneous data. BINGO is an annotation mining tool for biological interpretation of gene groups. Several statistical modeling approaches using Gene Ontology (GO) have been employed in many programs for that purpose. The statistical methodologies are useful in investigating the most significant GO attributes in a gene group, but the coherence of the resultant GO attributes over the entire group is rarely assessed. BINGO complements the statistical methods with graph-theoretic measures using the GO directed acyclic graph (DAG) structure. In addition, BINGO visualizes the consistency of a gene group more intuitively with a group-based GO subgraph. The input group can be any interesting list of genes or gene products regardless of its generation process if the group is built under a functional congruency hypothesis such as gene clusters from DNA microarray analysis.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.3
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• pp.86-95
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• 2009

Efficient DAG scheduling is critical for achieving high performance in heterogeneous computing environments. Finding an optimal solution to the problem of scheduling an application modeled by a directed acyclic graph(DAG) onto a set of heterogeneous machines is known to be an NP-complete problem. In this paper we propose a new list scheduling algorithm, called the Heterogeneous Rank-Path Scheduling(HRPS) algorithm, to exploit all of a program's available parallelism in distributed heterogeneous computing system. The primary goal of HRPS is to minimize the schedule length of applications. The performance of the algorithm has been observed by its application to some practical DAGs, and by comparing it with other existing scheduling algorithm such as CPOP, HCPT and FLB in term of the schedule length. The comparison studies show that HRPS significantly outperform CPOP, HCPT and FLB in schedule length.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.11
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• pp.603-609
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• 2003

Adaptive routing methods are studied for effective routing in many topologies where occurrence of the faulty nodes are inevitable. Mesh topology provides simplicity in implementing these methods. Many routing methods for mesh are able to tolerate a large number of faults enclosed by a rectangular faulty block. But they consider even good nodes in the faulty block as faulty nodes. Hence, it results the degradation of node utilization. This problem is solved by a method which transmits messages to destinations within faulty blocks via multiple “intermediate nodes”. It also divides faulty block into multiple expanded meshes. With these expanded meshes, DAG(Directed Acyclic Graph) is formed and a message is able to be routed by the shortest path according to the DAG. Therefore, the additional number of hops can be resulted. We propose a method that reduces the number of hops by searching direct paths from the destination node to the border of the faulty block. This path is called SCP(Short-Cut Path). If the path and the traversing message is on the same side of outside border of the faulty block, the message will cut into the path found by our method. It also reduces the message traverse latency between the source and the destination node.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.2
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• pp.135-148
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• 2000

In this paper, we present a linear scheduling method for homogeneous multiprocessor systems using genetic algorithms. In general, genetic algorithms randomly generate initial strings, which leads to long operation time and slow convergence due to an inappropriate initialization. The proposed algorithm considers communication costs among processors and generates initial strings such that successive nodes are grouped into the same cluster. In the crossover and mutation operations, the algorithm maintains linearity in scheduling by associating a node with its immediate successor or predecessor. Linear scheduling can fully utilize the inherent parallelism of a given program and has been proven to be superior to nonlinear scheduling on a coarse grain DAG (directed acyclic graph). This paper emphasizes the usability of the genetic algorithm for real-time applications. Simulation results show that the proposed algorithm rapidly converges within 50 generations in most DAGs.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.135-145
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• 2010

Efficient Directed Acyclic Graph(DAG) scheduling is critical for achieving high performance in Distributed Heterogeneous computing System(DHCS). In this paper, we present a new high-performance scheduling algorithm, called the LCFT(Levelized Critical First Task) algorithm, for DHCS. The LCFT algorithm is a list-based scheduling that uses a new attribute to efficiently select tasks for scheduling in DHCS. The complexity of LCFT is $O(\upsilon+e)(p+log\;\upsilon)$. The performance of the algorithm has been observed by its application to some practical DAGs, and by comparing it with other existing scheduling algorithms such as PETS, HPS, HCPT and GCA in terms of the schedule length and SpeedUp. The comparison studies show that LCFT significantly outperforms PETS, HPS, HCPT and GCA in schedule length, SpeedUp.

• The Korean Journal of Applied Statistics
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• v.36 no.1
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• pp.63-83
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• 2023

Many existing studies have found significant correlations between green spaces, including urban parks, and children's happiness. Furthermore, it was implied that the area/proximity of the urban park would be effective in enhancing infancy happiness. However, inferring causal effects from observed data requires appropriate adjustment of confounding variables, and from this perspective, the causal relationship between the area of urban parks and children's happiness has not been well understood. The causal effect of urban parks on children's happiness was estimated in this study using data from the panel study on Korean children. As methods for adjusting confounding variables, regression adjustment using a regression method, weighting method, and matching method were used, and key concepts of each method were described before the analysis results. Confounders were chosen for the analysis using a directed acyclic graph. In contrast to previous research, the analysis found no significant causal relationship between the size of the city park and children's happiness.

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.27-38
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• 1996

The aim of this paper is to develop more fast algorithm for evaluation of the reliability of networks and system. It is illustrated with examples. This paper derived the algorithm to calculate the acyclic directed graph G(deals with the problem of the s-t graph). The language PASCAL was used to implement the algorithm. Three Examples are calculated and the calculation time is shorter than the time by program in $\ulcorner$21$\lrcorner.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.151-155
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• 2001

Mobile agent technology has been the subject of much attention in the last few years, mainly due to the proliferation of distributed software technologies combined with the distributed AI research field. In this paper, we present a design of communication networks of agents that cooperate with each other for forwarding messages to the specific mobile agent in order to make the overall system location transparent. In order to make the material accessible to general intelligent system researchers, we present the general ideas abstractly in terms of the graph theory. In particular, a proxy network is defined as a directed acyclic graph satisfying some structural conditions. In turns out that the definition ensures some kind of reliability of the network, in the sense that as long as at most one proxy agent is abnormal, there agent exists a communication path, from every proxy agent to the target agent, without passing through the abnormal proxy. As the basis for the implementation of this scheme, an appropriate initial proxy network is specified and the dynamic nature of the network is represented by a set of graph transformation rules. It is shown that those rules are sound, in the sense that all graphs created from the initial proxy network by zero or more applications of the rules are guaranteed to be proxy networks. Finally, we will discuss some implementation issues.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.349-351
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• 2002

XML문서를 작성하는데 있어서 그 규칙이나 DTD에 익숙하지 않은 개발자에게 구문 지향 편집기는 효율적인 환경을 제공해 준다. 이러한 구문 지향 편집기를 생성하는 도구로서 Synthesizer Generator등이 잘 알려져 있는데, 사용자는 Synthesizer Generator를 위해 구문 지향 편집기 생성 정보 표현 언어인 SSL(Syntheizer Specification Language)을 직접 작성해야 한다. 본 연구는 웹 문서 표준인 XML 구문 지향 편집기를 자동 생성하기 위한 방법을 제안한다. 제안된 방법은 입력된 XML DTD를 AST 형태로 변경하여DAG(Directed Acyclic Graph)를 추출하는 DAG 변환기, 생성된 DAG를 SSL로 변환하기 위한 DAG 핸들러와 SSL 변환기 모듈 그리고 변환된 SSL을 이용해 XML 구문 지향 편집기를 자동 생성하기 위한 Synthesizer Generator 사창을 포함한다. SSL 변환기는 SSL문서를 자동 생성하기 위한 모듈로서 추상 구문변환 모듈 역 파싱(Unparsing scheme)모듈 변형 규칙(Transformation rule) 표현 모듈로 구성된다. 사용자는 SSL변환기와 Synthesizer Generator의 사용을 통해 SSL을 직접 코딩해야 하는 노력과 불필요한 학습시간을 줄이고 빠르고 정확한 XML 구문 지향 편집기를 생성하므로 효율적인 XML 문서 작성할 수 있다.