• 한국컴퓨터정보학회논문지
• /
• 제20권5호
• /
• pp.31-39
• /
• 2015

방향 가중 그래프의 차수제약 최소신장트리 (degree-constrained minimum spanning tree, d-MST) 문제는 정확한 해를 구하는 다항시간 알고리즘이 존재하지 않아 NP-완전 문제로 알려져 왔다. 따라서 휴리스틱한 근사 알고리즘을 적용하여 최적 해를 구하고 있다. 본 논문은 차수와 사이클을 검증하는 Kruskal 알고리즘으로 d-MST의 초기 해를 구하고, d-MST의 초기 해에 대해 k-opt를 수행하여 최적 해를 구하는 다항시간 알고리즘을 제안하였다. 제안된 알고리즘을 4개의 그래프에 적용한 결과 2-MST까지 최적 해를 구할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권8호
• /
• pp.3086-3101
• /
• 2021

To supply precise marketing and differentiated service for the electric power service department, it is very important to predict the customers with high sensitivity of electric power failure. To solve this problem, we propose a novel grouped 𝑙_1/2 sparsity constrained logistic regression method for sensitivity assessment of electric power failure. Different from the 𝑙₁ norm and k-support norm, the proposed grouped 𝑙_1/2 sparsity constrained logistic regression method simultaneously imposes the inter-class information and tighter approximation to the nonconvex 𝑙₀ sparsity to exploit multiple correlated attributions for prediction. Firstly, the attributes or factors for predicting the customer sensitivity of power failure are selected from customer sheets, such as customer information, electric consuming information, electrical bill, 95598 work sheet, power failure events, etc. Secondly, all these samples with attributes are clustered into several categories, and samples in the same category are assumed to be sharing similar properties. Then, 𝑙_1/2 norm constrained logistic regression model is built to predict the customer's sensitivity of power failure. Alternating direction of multipliers (ADMM) algorithm is finally employed to solve the problem by splitting it into several sub-problems effectively. Experimental results on power electrical dataset with about one million customer data from a province validate that the proposed method has a good prediction accuracy.

• Journal of applied mathematics & informatics
• /
• 제25권1_2호
• /
• pp.305-314
• /
• 2007

This paper considers single machine scheduling problems where the processing time of a job increases as a function of its position in the sequence. In this model, the later a given job is scheduled in the sequence, the longer its processing time. It is shown that the optimal schedule may be very different from that of the classical version of the problem. We introduce polynomial solutions for the makespan minimization problem, the sum of completion times minimization problem and the sum of earliness penalties minimization problem. For two resource constrained problems, based on the analysis of the problems, the optimal resource allocation methods are presented, respectively.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제12권1호
• /
• pp.20-28
• /
• 2012

We define a language $\mathcal{RS}$, a subclass of the scheduling language $\mathcal{RS}V$ (resource constrained project scheduling with variant processes). $\mathcal{RS}$ involves the determination of the starting times for ground activities of a project satisfying precedence and resource constraints, in order to minimize the total project duration. In $\mathcal{RS}$ ground activities and two structural symbols (operators) 'seq' and 'pll' are used to construct activity-terms representing scheduling problems. We consider three different variants for formalizing the $\mathcal{RS}$-scheduling problem, the optimizing variant, the number variant and the decision variant. Using the decision variant we show that the problem $\mathcal{RS}$ is $\mathcal{NP}$-complete. Further we show that the optimizing variant (or number variant) of the $\mathcal{RS}$-problem is computable in polynomial time iff the decision variant is computable in polynomial time.

• Journal of applied mathematics & informatics
• /
• 제20권1_2호
• /
• pp.181-195
• /
• 2006

Resource-constrained project scheduling problems with variant processes can be represented and solved using a logic-based terminological language called RSV (resource constrained project scheduling with variant processes). We consider three different variants for formalizing the RSV-scheduling problem, the optimizing variant, the number variant and the decision variant. Using the decision variant we show that the RSV- problem is NP-complete. Further we show that the optimizing variant (or number variant) of the RSV-problem is computable in polynomial time iff. the decision variant is computable in polynomial time.

• 한국컴퓨터산업학회논문지
• /
• 제10권5호
• /
• pp.201-206
• /
• 2009

시간표 문제는 제약조건을 만족하는 최적화 문제이다. 대부분의 최적화 알고리즘은 일단 시간표를 생성하고 이를 반복적으로 변형하고 재구성하는 전략을 통해 최적에 도달하는 방법을 이용하고 있다. 시간표 문제는 자원이 부족한 경우에 초기해를 만드는 과정에서부터 어려움을 겪게 된다. 초기해를 만들기 위한 대표적인 방법은 높은 제약조건을 갖는 과목 먼저 배정하는 것이다. 여기서 제약 조건의 정도를 수치화 한 것을 자유도라고 한다. 본 연구에서는 이 자유도를 정의하고 실험을 통해 자유도의 역할을 살펴보고자 한다.

• Interaction and multiscale mechanics
• /
• 제5권3호
• /
• pp.211-228
• /
• 2012

This paper reports the development of a generalized inverse analysis formulation for the parameter estimation of four-parameter Burger model. The analysis is carried out by formulating the problem as a mathematical programming formulation in terms of identification of the design vector, the objective function and the design constraints. Thereafter, the formulated constrained nonlinear multivariable problem is solved with the aid of fmincon: an in-built constrained optimization solver module available in MatLab. In order to gain experience, a synthetic case-study is considered wherein key issues such as the determination and setting up of variable bounds, global optimality of the solution and minimum number of data-points required for prediction of parameters is addressed. The results reveal that the developed technique is quite efficient in predicting the model parameters. The best result is obtained when the design variables are subjected to a lower bound without any upper bound. Global optimality of the solution is achieved using the developed technique. A minimum of 4-5 randomly selected data-points are required to achieve the optimal solution. The above technique has also been adopted for real-time settlement of four oil refineries with encouraging results.

• 한국경영과학회지
• /
• 제27권4호
• /
• pp.185-205
• /
• 2002

In this study, we consider infinite supply of raw materials and backlogged demands as given two boundary conditions. And we need not make any specific assumptions about the inter-arrival of external demand and service time distributions. Under these situations, the ultimate objective of this study is to prove the variability propagation principle in a pull serial line and is to measure it in terms of the first two moments of the inter-departure process subject to number of cards in each cell. Two preparations are required to achieve this objective : The one is to derive a true lower bound of variance of the inter-departure process. The other is to establish a constrained discrete minimax problem for the no backorder (backlogging) probabilities in each cell. We may get some fundamental results necessary to a completion for the proof through the necessary and sufficient conditions for existence of optimal solution of a constrained discrete minimax problem and the implicit function theorem. finally, we propose a numeric model to measure the variability propagation principle. Numeric examples show the validity and applicability of our study.

• 한국소음진동공학회논문집
• /
• 제18권2호
• /
• pp.185-191
• /
• 2008

Optimal damping layout of the constrained viscoelastic damping layer on beam is identified with temperatures by using a gradient-based numerical search algorithm. An optimal design problem is defined in order to determine the constrained damping layer configuration. A finite element formulation is introduced to model the constrained layer damping beam. The four-parameter fractional derivative model and the Arrhenius shift factor are used to describe dynamic characteristics of viscoelastic material with respect to frequency and temperature. Frequency-dependent complex-valued eigenvalue problems are solved by using a simple re-substitution algorithm in order to obtain the loss factor of each mode and responses of the structure. The results of the numerical example show that the proposed method can reduce frequency responses of beam at peaks only by reconfiguring the layout of constrained damping layer within a limited weight constraint.

• 대한산업공학회지
• /
• 제6권2호
• /
• pp.21-29
• /
• 1980

본(本) 연구(硏究)는 투자안(投資案)들간의 상호관계(相互關係) 및 위험(危險)을 고려한 자본예산문제(資本豫算問題)를 다루고 있다. 기존(旣存)의 개발(開發)된 모형(模型)은 확률제약조건계획모형(確率制約條件計劃模型) 및 기대효용극대화모형(期待效用極大化模型)의 두 범주(範疇)로 구분(區分)될 수 있다. 전자의 경우 목적함수(目的凾數)가 다소 제약적(制約的)이며 위험(危險)을 직접적인 형태로 고려하지 않고 있는 반면에 후자는 기대효용(期待效用)에 대한 근사치(近似値)를 사용하기 때문에 투자결정(投資決定)이 최적화(最摘化)되지 못할 가능성이 있다. 본(本) 연구(硏究)는 목적함수(目的凾數)를 보다 일반적(一般的)인 형태로 수정(修正) 보완(補完)함으로써 현실적용성(現實適用性)을 높이고자 하였다. 해법절차(解法節次)로는, 자본예산문제(資本豫算問題)를 우선 비선형(非線型) 0-1 정수계획(整數計劃) 문제로 정식화(定式化)하고, 이를 선형(線型) 0-1 정수계획(整數計劃)문제로 변형(變形)하여 원문제(原問題)의 하한(下限)을 찾은 후 B&B 연산법(演算法)으로 원문제(原問題)의 최적해(最適解)를 구하고 있다.