• Journal of the Korea Computer Graphics Society
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• v.16 no.2
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• pp.9-17
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• 2010

Minkowski sum of two polyedra is an operation to compute the sum of all pairs of points contained in the polyhedra. It has been a very useful tool to solve many geometric problems arising in the areas of robotics, NC machining, solid modeling, and so on. However, very few algorithms have been proposed to compute Minkowski sum of polyhedra, because computing Minkowski sum boundaries is susceptible to roundoff errors. We propose an algorithm to robustly compute the Minkowski sum boundaries by employing the controlled linear perturbation scheme to prevent numerically ambiguous and degenerate cases from occurring. According to our experiments, our algorithm computes the Minkowski sum boundaries with the precision of $10^{-14}$ by perturbing the vertices of the input polyhedra up to $10^{-10}$.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2897-2907
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• 1998

The production-rule generation from training examples is a hard problem that has large space and many local optimal solutions. Many learning methods are proposed for production-rule generation and genetic algorithms is an alternative learning method. However, traditional genetic algorithms has been known to have an obstacle in converging at the global solution area and show poor efficiency of production-rules generated. In this paper, we propose a production-rule generating method which uses genetic algorithm learning. By analyzing optimal sub-solutions captured by genetic algorithm learning, our method takes advantage of its schema structure and thus generates relatively small rule set.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.213-219
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• 2016

This paper presents a branch-and-bound algorithm for solving the concave minimization problem with upper bounded variables whose single constraint is linear. The algorithm uses simplex as partition element. Because the convex envelope which most tightly underestimates the concave function on the simplex is uniquely determined by solving the related linear equations. Every branching process generates two subsimplices one lower dimensional than the candidate simplex by adding 0 and upper bound constraints. Subsequently the feasible points are partitioned into two sets. During the bounding process, the linear programming problems defined over subsimplices are minimized to calculate the lower bound and to update the incumbent. Consequently the simplices which do certainly not contain the global minimum are excluded from consideration. The major advantage of the algorithm is that the subproblems are defined on the one less dimensinal space. It means that the amount of work required for the subproblem decreases whenever the branching occurs. Our approach can be applied to solving the concave minimization problems under knapsack type constraints.

• KDI Journal of Economic Policy
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• v.16 no.1
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• pp.3-92
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• 1994

경제정책(經濟政策) 변화(變化)의 효과(效果)를 실증분석(實證分析)할 때, 거시경제(巨視經濟) 변동(變動)에 관심이 있는 경우 거시계량모형(巨視計量模型)을 활용하고, 상대가격구조(相對價格構造) 변동(變動)에 대한 소비자(消費者) 및 생산자(生産者)의 반응에 관심이 있는 경우 일반균형연산모형(一般均衡演算模型)을 사용한다. 그런데 대체로 정책변수(政策變數)는 경제구조(經濟構造)(미시적(微視的) 효과(效果))와 경기순환(景氣循環)(거시적(巨視的) 효과(效果))에 동시적 영향을 주기 때문에, 위의 두 모형(模型) 중 어느 하나만으로는 미시행태와 거시현상을 연계 분석하거 어렵다. 본고(本稿)에서는 정책변수(政策變數)의 변화(變化)가 경제주체(經濟主體)의 개별적 최적화(最適化) 행태(行態)와 집합적(集合的) 행태(行態)에 미치는 영향을 동시에 파악하기 위해 이 두 모형(模型)을 결합한 미시(微視)-거시통합모형(巨視統合模型)을 개발하였다. 통합모형(統合模型)의 결과에 의하면, 일반균형모형(一般均衡模型)에 편입(編入)된 거시계량모형(巨視計量模型)과 동태화(動態化)된 일반균형연산모형(一般均衡演算模型)을 결합하여 단기(短期) 경기순환(景氣循環) 및 중장기(中長期)에 걸친 구조조정(構造調整) 문제(問題)를 동시에 분석 가능한 실증분석(實證分析) 도구(道具)를 개발할 수 있었다. 설제로 본고(本稿)에서는 정책대안효과(政策代案效果)의 정량적(定量的) 평가(評價)를 위하여 통합모형(統合模型)을 가상적인 석탄가격(石炭價格) 자율화(自律化)와 보조금(補助金) 지원제도(支援制度) 변화(變化)의 효과분석에 활용하여 보았다. 이러한 모의실험(模擬實驗)은 다른 정책효과분석(政策效果分析)에도 활용(活用)될 수 있을 것이다.

• Journal of KIISE:Databases
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• v.29 no.1
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• pp.34-43
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• 2002

Since traditional static metadata set like Dublin Core has static metadata attributes about bibliography information, integration of metadata for various metadata, problems about standard and extension of metadata must be considered for applying it to new environment. Specially, as event-driven metadata write method included the notion of e-commerce come out for interoperability in digital libraries, traditional metadata management which cannot distinguish between different kinds of update operations to new extension of metadata set occurs unsuitable waiting of update operation. So, improvement is needed about it. In this paper, we show whether alleviative transaction consistency can be applied to digital library or not. Also it would divide newer metadata into static metadata attribute connected in read operation within user read-only transaction and dynamic metadata attribute in update operation within dynamic(e-commerce) update transactions. We propose newer metadata management algorithm considered in classfication of metadata attributes and dynamic update transaction. Using two version for minimal maintenance cost and ARU(Appended Refresh Unit) for dynamic update transaction, to minimize conflict between read and write operations shows fast response time and high recency ratio. As a result of the performance evaluation, we show our algorithm is proved to be better than other algorithms in newer metadata environments.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.657-660
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• 2006

최근까지 데이터웨어하우스와 OLAP 에 관한 연구와 더불어 데이터 큐브(data cube)는 많은 다차원 데이터웨어하우스에서 데이터 분석과 의사 결정 지원을 위해 빠르게 OLAP 연산을 처리하기 위한 중요한 역할을 수행해 왔다. 최근에는 빠른 속도로 생성됨과 동시에 지속적으로 발생되는 연속적인 데이터로 구성된 데이터 스트림이 네트워크 트래픽 모니터링, 증권, 날씨, 콜 센터 등과 같은 많은 분야에서 생성된다. 데이터 스트림은 무한의 집합이기 때문에 기존의 데이터 큐브 방법은 처리시간과 저장공간의 문제 때문에 데이터 스트림에 적용하기 어렵다. 이에 본 논문에서는 기존의 데이터 큐브와 같은 데이터의 요약 정보를 데이터 스트림 환경에서 제한된 메모리를 이용하여 관리 할 수 있는 전원트리를 이용한 데이터 스트림 요약 기법을 제안하고, 실험을 통해 본 논문에서 제안한 방법이 데이터 스트림 환경에서 적응적으로 동작함을 증명한다.

• Journal of the Korean Data and Information Science Society
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• v.20 no.6
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• pp.1015-1027
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• 2009

Many problems of confounding and identifiability for polynomial models in an experimental design can be solved using methods of algebraic geometry. The theory of $Gr\ddot{o}bner$ basis is used to characterize the design. In addition, a fractional factorial design can be uniquely represented by a polynomial indicator function. $Gr\ddot{o}bner$ bases and indicator functions are powerful computational tools to deal with ideals of fractions based on each different theoretical aspects. The problem posed here is to give how to move from one representation to the other. For a given fractional factorial design, the indicator function can be computed from the generating equations in the $Gr\ddot{o}bner$ basis. The theory is tested using some fractional factorial designs aided by a modern computational algebra package CoCoA.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.980-984
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• 2010

Exploring microRNA (miRNA) and mRNA regulatory interactions may give new insights into diverse biological phenomena. Recently, miRNAs have been discovered as important regulators that play a major role in various cellular processes. Therefore, it is essential to identify functional interactions between miRNAs and mRNAs for understanding the context- dependent activities of miRNAs in complex biological systems. While elucidating complex miRNA-mRNA interactions has been studied with experimental and computational approaches, it is still difficult to infer miRNA-mRNA regulatory modules. Here we present a novel method, termed layered hypernetworks (LHNs), for identifying functional miRNA-mRNA interactions from heterogeneous expression data. In experiments, we apply the LHN model to miRNA and mRNA expression profiles on multiple cancers. The proposed method identifies cancer-specific miRNA-mRNA interactions. We show the biological significance of the discovered miRNA- mRNA interactions.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.51-57
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• 2014

In this paper, we introduce the adaptive threshold detection scheme based on an evolutionary arithmetic algorithm for the M-ary holographic data storage(HDS) system. The genetic algorithm is a particular class of evolutionary arithmetic based on the process of biological evolution, which is a very promising technique for optimization problem and estimation applications. In this study, to improve the detection performance that is degraded by the HDS channel environment and the pixel misalignment, the threshold value was assumed to be a population set of the evolutionary algorithm. The proposed method can find an appropriate population set of bit threshold, which minimizes bit error rate(BER) as increased generation. For performance evaluation, we consider severe misalignment effect in the 4-ary holographic data storage system. Furthermore, we measure the BER performance and compare the proposed methods with the conventional threshold detection scheme, which verifies the superiority of the proposed scheme.

• Korean Journal of Remote Sensing
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• v.11 no.3
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• pp.49-60
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• 1995

Features of geological lineaments generally play an important role at the data interpretation concerned geological processes, mineral exploration or natural hazard risk estimation. However, there are intrinsically discordances between lineaments-related features extracted from surficial geological syrvey and those from satellite imagery;nevertheless, any data set contained those information should not be considred as less meaningful within their own task. For the purpose of effective utilization task of extracted lineaments, the mathematical scheme, based on fuzzy set theory, for practical integration of various types of rasterized data sets is studied. As a real application, the geological map named Homyeong sheet(1:50,000) and the Landset TM imageries covering same area were used, and then lineaments-related data sets such as lineaments on the geological map, lineaments extracted from a false-color image composite satellite, and major drainage pattern were utilized. For data fusion process, fuzzy membership functions of pixel values in each data set were experimentally assigned by percentile, and then fuzzy algebraic sum operator was tested. As a result, integrated lineaments by this well-known operator are regarded as newly-generated reasonable ones. Conclusively, it was thought that the implementation within available GISs, or the stand-alone module for general applications of this simple scheme can be utilized as an effective scheme can be utilized as an effective scheme for further studies for spatial integration task for providing decision-supporting information, or as a kind of spatial reasoning scheme.