• Communications for Statistical Applications and Methods
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• 제12권1호
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• pp.207-216
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• 2005

A binary segmentation procedure is a simple recursive approach to detect clusters and provide inferences for the study space when the shape of the clusters and the number of clusters are unknown. The procedure involves a sequence of nested hypothesis tests of a single cluster versus a pair of distinct clusters. The size and the shape of the clusters evolve as the procedure proceeds. The procedure allows for various growth clusters and for arbitrary baseline densities which govern the form of the hypothesis tests. A real tree data is used to highlight the procedure.

• 한국정보처리학회논문지
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• 제4권10호
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• pp.2596-2604
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• 1997

ACK는 가상 스택 기계에 기반을 둔 EM 중간 코드로부터 레지스터 구조에 기반을 둔 SPARC 기계에 대한 목적 코드를 생성하기 위해서는 코드 확장기(code expander)를 이용하고 있다. 따라서 EM 코드로부터 SPARC 목적 코드를 생성하기 위해 스택 지향 구조로부터 레지스터 지향 구조로 변환하여야 한다. 코드 확장기를 이용한 SPARC 코드 생성 기법은 각 EM 명령어에 대해 SPARC 코드로 확장하는 루틴들로 구성되며 코드 생성기에 비해 코드의 질을 개선하기 위해 푸쉬-팝 최적화 동작을 수행한다. 하지만 코드 확장시에 별도의 자원과 관리를 요구하는 혼합 스택(hybrid stack)을 이용하고 있으며 전단부의 정보 손실로 레지스터 윈도우를 이용한 효율적인 매개변수 전달을 고려하지 않는다. 본 논문에서는 ACK의 전체적인 구조의 변경 없이 목적 기계의 스택과 매개변수 전달을 고려하나 효율적인 SPARC 코드를 생성하기 위해 EM 트리를 이용한 SPARC 코드 확장기를 설계하고 구현하였다. 이를 위해, 순차적인 EM 코드를 입력으로 받아 스택 속성을 반영한 트리로 구성하며 혼합 스택을 제거하기 위해 지역 변수 정보를 별도로 관리하였다. EM 트리의 순회 및 확장 과정에서 목적 코드를 생성할 수 있는 루틴을 통하여 목적 코드를 출력하며 추출된 정보와 노드의 성격에 출력 시기와 목적 코드를 결정한다.

• 한국경영과학회지
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• 제33권3호
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• pp.17-28
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• 2008

The Steiner arborescence problem is known to be NP-hard. The objective of this problem is to find a minimal Steiner tree which starts from a designated node and spans all given terminal nodes. This paper proposes a method based on a two-step procedure to solve this problem efficiently. In the first step, graph reduction rules eliminate useless nodes and arcs which do not contribute to make an optimal solution. In the second step. ant colony algorithm with use of Prim's algorithm is used to solve the Steiner arborescence problem in the reduced graph. The proposed method based on a two-step procedure is tested in the five test problems. The results show that this method finds the optimal solutions to the tested problems within 50 seconds. The algorithm can be applied to undirected Steiner tree problems with minor changes. 18 problems taken from Beasley are used to compare the performances of the proposed algorithm and Singh et al.'s algorithm. The results show that the proposed algorithm generates better solutions than the algorithm compared.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권8호
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• pp.752-758
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• 2005

수송문제는 산업공학 및 OR 그리고 전자계산학 분야에서 중요한 문제 중의 하나로 인식된다. 수송 문제가 시설을 수립하거나 고객들의 요구를 이행하기 위한 추가적인 고정 비용과 연관될 때, fcTP(fixed charge Transportation Problem)라 한다. fcTP는 이전의 고전적인 방법으로 해결하기 어려운 NP-hard 문제들 중의 하나이다. 본 논문에서는 비선형 fcTP를 해결하기 위한 신장트리 기반 유전자알고리즘을 제안한다. 특히, 염색체(chromosome)에 대한 feasibility criteria와 repairing procedure를 포함하는 GA 염색체 표현에 대해 새로운 아이디어를 제안한다. 또한, 본 논문에서 제안하는 방법의 효율성을 입증하기 위한 여러 가지 수치 실험 결과를 기술한다.

• Industrial Engineering and Management Systems
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• 제10권4호
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• pp.272-278
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• 2011

Decision tree as a classification tool is being used successfully in many areas such as medical diagnosis, customer churn prediction, signal detection and so on. The main advantage of decision tree classifiers is their capability to break down a complex structure into a collection of simpler structures, thus providing a solution that is easy to interpret. Since decision tree is a top-down algorithm using a divide and conquer induction process, there is a risk of reaching a local optimal solution. This paper proposes a procedure of optimally determining thresholds of the chosen variables for a decision tree using an adaptive particle swarm optimization (APSO). The proposed algorithm consists of two phases. First, we construct a decision tree and choose the relevant variables. Second, we find the optimum thresholds simultaneously using an APSO for those selected variables. To validate the proposed algorithm, several artificial and real datasets are used. We compare our results with the original CART results and show that the proposed algorithm is promising for improving prediction accuracy.

• Computers and Concrete
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• 제17권6호
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• pp.761-786
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• 2016

This paper proposes an automated procedure for optimum seismic design of reinforced concrete (RC) frame structures. This procedure combines a smart pre-processing using a Tree Classification Method (TCM) and a nonlinear optimization technique. First, the TCM automatically creates sections database and assigns sections to structural members. Subsequently, a real valued model of Particle Swarm Optimization (PSO) algorithm is employed in solving the optimization problem. Numerical examples on design optimization of three low- to high-rise RC frame structures under earthquake loads are presented with and without considering strong column-weak beam (SCWB) constraint. Results demonstrate the effectiveness of the TCMin seismic design optimization of the structures.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.365-370
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• 1997

In this paper we suggest a development of surface defect inspection algorithms for cold mill strip using tree structure. The defects which exist in a surface of cold mill strip have a scattering or singular distribution. This paper consists of preprocessing, feature extraction and defect classification. By preprocessing, the binarized defect image is achieved. In this procedure, Top-hit transform, adaptive thresholding, thinning and noise rejection are used. Especially, Top-hit transform using local min/max operation diminishes the effect of bad lighting. In feature extraction, geometric, moment, co-occurrence matrix, histogram-ratio features are calculated. The histogram-ratio feature is taken from the gray-level image. For the defect classification, we suggest a tree structure of which nodes are multilayer neural network clasifiers. The proposed algorithm reduced error rate comparing to one stage structure.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.413-418
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• 1992

This paper presents a tree search technique to solve the dynamic control problems. To illustrate the proposed procedure, the swinging control of a pendulum carried by a motor-driven cast is discussed as an example. Since the control system is of two degrees and the control problem is a nonlinear one, it is difficult to determine a swinging control rule analytically. However, by means of the proposed tree search approach, the problem can be solved in a relatively easy way. Some numerical calculations axe performed to verify the methodology. The result of the study shows that the proposed tree search technique is suitable for the dynamic control problems, in particular, for the complicated nonlinear dynamic control problem.

• 경영과학
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• 제26권1호
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• pp.65-76
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• 2009

The undirected Steiner tree problem in graphs is known to be NP-hard. The objective of this problem is to find a shortest tree containing a subset of nodes, called terminal nodes. This paper proposes a method based on a two-step procedure to solve this problem efficiently. In the first step. graph reduction rules eliminate useless nodes and edges which do not contribute to make an optimal solution. In the second step, a max-min ant colony optimization combined with Prim's algorithm is developed to solve the reduced problem. The proposed algorithm is tested in the sets of standard test problems. The results show that the algorithm efficiently presents very correct solutions to the benchmark problems.

• 대한안전경영과학회지
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• 제4권1호
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• pp.37-47
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• 2002

Risk analysis is a formal deductive procedure for determining combinations of component failures and human errors that could result in the occurrence of specified undesired events at the system level. This method can be used to analyze the vast majority of industrial system reliability problems. This study deals with the application of knowledge-engineering and a methodology for the assessment ＆ measurement of reliability, availability, maintainability, and safety of industrial systems using FTA(fault tree analysis), A fuzzy methodology for fault-tree evaluation seems to be an alternative solution to overcome the drawbacks of the conventional approach (insufficient Information concerning the relative frequencies of hazard events). To improve the quality of results, the membership functions must be approximated based on heuristic considerations, The purpose of this study is to describe the knowledge engineering approach, directed to integrate the various sources of knowledge involved in a FTA.