Earticle

안정적인 수돗물 공급을 목적으로 하는 상수도 시설은 설계비용과 에너지 비용 등 총 비용을 저감할 수 있도록 계획되어야 한다. 상수관망 설계 시 관경에 따라 설계비용이 달라지고 마찰 손실 에너지가 달라지기 때문에 적절한 관경을 결정하는 것이 효과적인 관망 관리에 도움이 된다. 본 연구에서는 설계비 용의 최소화와 마찰 손실 에너지의 최소화를 목적으로 하는 다목적 최적화 연구를 수행하기 위해 비지배 정렬 유전자 알고리즘(NSGA-Ⅱ)과 상수관망 프로그램인 EPANET을 연계하여 적용하였다. 대상지역은 인천시 청라지역 3개의 동으로 하였고, 마찰 손실 에너지를 산출하기 위한 관 내의 유량과 마찰 손실 수두는 EPANET 모델 결과를 활용하였다. 연구를 통하여 대상지역 상수관망 내 수요량과 압력을 충족시 키면서 설계비용과 마찰 손실 에너지의 파레토 프런트를 구성하였다. 또한, 비지배 정렬 유전자를 이용하 여 두 목적함수를 만족시키는 관망의 최적 설계 연구가 가능하다는 것을 제시하였다.

Water supply system that provide safe water to customers should be designed to reduce construction cost and management cost. Pipe diameter is a key aspect of water distribution system since it affects design cost and friction loss. This study applied multi-objective optimization algorithm coupled with EPANET hydraulic solver for minimizing design cost and friction loss energy to water distribution system. Non-dominated sorting genetic algorithm (NSGA-Ⅱ) was used as an optimization technique. The hydraulic results such as head loss and flow in the pipeline were obtained from EPANET program. The test bed was the Cheongna water distribution system in Incheon, Korea. The findings in this study provided Pareto front of minimizing design cost and friction loss energy with simultaneously satisfying the water demand and hydraulic pressure. This study suggests that NSGA-Ⅱ can be used to design optimal water distribution system that satisfy the multi-objective options.

This paper presents a scheduling problem for a high-density robotic workcell using multi-objective genetic algorithm. We propose a new algorithm based on NSGA-II(Non-dominated Sorting Algorithm-II) which is the most popular algorithm to solve multi-objective optimization problems. To solve the problem efficiently, the proposed algorithm divides the problem into two processes: clustering and scheduling. In clustering process, we focus on multi-robot positions because they are fixed in manufacturing system and have a great effect on task distribution. We test the algorithm by changing multi-robot positions and compare it to previous work. Test results shows that the proposed algorithm is effective under various conditions.

Dynamic process planning requires not only more flexible capabilities of a CAPP system but also higher utility of the generated process plans. In order to meet the requirements, this paper develops an algorithm that can select machines for the machining operations by calculating the machine loads. The developed algorithm is based on the multi-objective genetic algorithm that gives rise to a set of optimal solutions (in general, known as the Pareto-optimal solutions). The objective is to satisfy both the minimization number of part movements and the maximization of machine utilization. The algorithm is characterized by a new and efficient method for nondominated sorting through K-means algorithm, which can speed up the running time, as well as a method of two stages for genetic operations, which can maintain a diverse set of solutions. The performance of the algorithm is evaluated by comparing with another multiple objective genetic algorithm, called NSGA-II and branch and bound algorithm.

In various machines used in industrial sites and transportation equipment, fastening structures of bolts and nuts are widely employed. However, conventional Steel sockets, classified as non-explosion-proof materials, have a high likelihood of generating sparks due to friction with components, which can lead to explosions or large-scale fires. To address this issue, this study developed a lightweight explosion-protection socket using AL-7075-T6 aluminum alloy, which is known for its excellent explosion-proof properties. However, due to the inherent characteristics of aluminum, it has lower rigidity compared to Steel, requiring the use of more expensive alloy materials. Therefore, our research team utilized Finite Element Analysis (FEA) and Multi-Objective Genetic Algorithm (MOGA) to optimize the mass and safety factor of the socket, proposing a design that simultaneously achieves both weight reduction and structural stability. The socket developed in this study is approximately 30% lighter than traditional Steel-based sockets while maintaining a safety factor of 1.2 or higher, significantly enhancing operational safety in explosive environments. This research sets a new standard in the design and manufacturing process of explosion-proof sockets and is expected to contribute to the optimization of various explosion-proof equipment in the future.

In recent years, several researches have been conducted on spectral clustering to classify non-linear data in various applications. Considering the effect of selecting the appropriate eigenvectors on spectral clustering performance; various methods have been proposed weighting and ranking features. However, these methods can independently evaluate the impact of each eigenvector. Nevertheless, it is possible that several eigenvectors have duplicate or inadequate information on some clusters. Thus, we have presented a new method for finding the optimal combination of eigenvectors by several different evaluation criteria. In order to detect simultaneously the optimum condition in various criteria, the multi-objective genetic algorithm is applied. Findings of performed experiments on datasets with various features demonstrate a resounding success in the proposed method.

This paper considers the problem of designing a Multilayer Survivable Optical Network for the customers’ Demands Problem called MSONDP. The network is modelled by two graphs: an undirected graph G1 = (V1, E1) and a complete undirected and weighted graph G2 = (V2, E2, c). The goal objective of this problem is to design connections based on customers’ demands with the smallest a minimum network cost to protect the network against all failures. This paper introduces a multi-objective approach for MSONDP. These objectives are to minimize the network cost (totalCost) and the maximum number of connections passing over a link (maxConn). Further, this paper also proposes a multi-objective genetic algorithm to solve this problem. The eExperimental results on real world and random instances are reported to show the efficiencyefficacy, in terms of minimizing the network cost, of the proposed algorithm comparing compared to the single genetic PGAMSONDP.

Based on the analysis on the basic principles and characteristics of the existing multi-objective genetic algorithm (MOGA), an improved multi-objective GA with elites maintain is put forward based on non-dominated sorting genetic algorithm (NSGA). NSGA-II algorithm theory and parallel hybrid evolutionary theory is described in detail. The design principle, process and detailed implementations of the improved MOGA are given. IMNSGA-II algorithm and NSGA-II algorithm are applied to test the performance of the two algorithms for different test function, experiments of example are preformed. Experimental results show that the improved MOGA achieved the optimal between the convergence and diversity.

Freshwater is limited resource and it is shrinking rapidly due to the urbanization, contamination and climate change impacts. As a result, raising water demands and insufficient freshwater resources become the main reasons of water conflicts. Optimal water allocation model would be an effective method to achieve the optimal allocation of limited water resources, in terms of the conjunctive use planning and management. In this paper, a multi-objective optimal water resources allocation model is proposed and the social, economic and environmental benefits are regarded as the optimal objective functions. The presented model is applied to a case of planning water resources management in China. Furthermore, simulations and optimization modeling methods have been conducted to solve the allocation model. The Gray Model has been used to predict the fresh water demand and storage of different user parts in 2025 and the Genetic Algorithm technique has been employed to solve the multi-objective problem. The obtained results illustrate how to allocate the quantity of different water resource to different users while achieving maximum social, economic and environmental benefits, which is valuable and helpful to develop a water resources optimal allocation strategy.

To effectively optimize multi-objective logistics distribution path, the distance and distance related customer satisfaction factor are used as the objective function, a novel kruskal crossover genetic algorithm (KCGA) for multi-objective logistics distribution path optimization is proposed. To test the optimization results, the terminal distribution model and the virtual logistics system operating model are built. Experiment results show that, compared with basic genetic algorithm (GA), the run time of KCGA takes a slightly higher. But the average distribution distance and the best distribution distance are reduced by 6%-8%. Achieve the goal of multi-objective logistics distribution path optimization.

Genetic algorithms for multi-objective optimization problem to be solved were studied. Through the elitist strategy analysis, it is an improved multi-objective optimization algorithm. The algorithm uses a data warehouse to store the optimal solution produced by individuals in each generation, from the way individuals adopt measures to phase out the individual data warehouse identical or similar, the algorithm also improved selection operator, so that the algorithm adaptive capacity enhancement, the new algorithm improves the algorithm performance, improves the quality of understanding between sets, can get a lot of optimal and balanced.

Ship hull optimization is categorized as a bound, multi variable, multi objective problem with nonlinear constraints. In such analysis, where the objective function representing the performance of the ship generally requires computationally involved hydrodynamic interaction evaluation methods, the objective functions are not smooth. Hence, the evolutionary techniques to attain the optimum hull forms is considered as the most practical strategy. In this study, a parametric ship hull form represented by B-Spline curves is optimized for multiple performance criteria using Genetic Algorithm. The methodology applied to automate the hull form generation, selection of optimization solvers and hydrodynamic parameter calculation for objective function and constraint definition are discussed here.

After the Tohoku earthquake and tsunami (Japan, 2011), regulatory efforts to mitigate external hazards have increased both the safety requirements and the total capital cost of nuclear power plants (NPPs). In these circumstances, identifying not only disaster robustness but also cost-effective capacity setting of NPPs has become one of the most important tasks for the nuclear power industry. A few studies have been performed to relocate the seismic capacity of NPPs, yet the effects of multiple hazards have not been accounted for in NPP capacity optimization. The major challenges in extending this problem to the multihazard dimension are (1) the high computational costs for both multihazard risk quantification and system-level optimization and (2) the lack of capital cost databases of NPPs. To resolve these issues, this paper proposes an effective method that identifies the optimal multihazard capacity of NPPs using a multi-objective genetic algorithm and the two-stage direct quantification of fault trees using Monte Carlo simulation method, called the two-stage DQFM. Also, a capacity-based indirect capital cost measure is proposed. Such a proposed method enables NPP to achieve safety and cost-effectiveness against multi-hazard simultaneously within the computationally efficient platform. The proposed multihazard capacity optimization framework is demonstrated and tested with an earthquake-tsunami example.

A design optimization system for Francis turbine was developed. The system consists of design program and CFD solver. Flow passage shapes are optimized automatically by using the system with Multi-Objective Genetic Algorithm (MOGA). In this study, the system was applied to a high specific speed Francis turbine (nSP = 250m-kW). The runner profile and the draft tube shape were optimized to decrease hydraulic losses. As the results, it was shown that the turbine efficiency was improved in wide operating range, furthermore, the height of draft tube was reduced with the hydraulic performance kept.

Structural design has an imperative role in deciding the failure possibility of a Reinforced Concrete (RC) structure. Recent research works achieved the goal of predicting the structural failure of the RC structure with the assistance of machine learning techniques. Previously, the Artificial Neural Network (ANN) has been trained supported by Particle Swarm Optimization (PSO) to classify RC structures with reasonable accuracy. Though, keeping in mind the sensitivity in predicting the structural failure, more accurate models are still absent in the context of Machine Learning. Since the efficiency of multi-objective optimization over single objective optimization techniques is well established. Thus, the motivation of the current work is to employ a Multi-objective Genetic Algorithm (MOGA) to train the Neural Network (NN) based model. In the present work, the NN has been trained with MOGA to minimize the Root Mean Squared Error (RMSE) and Maximum Error (ME) toward optimizing the weight vector of the NN. The model has been tested by using a dataset consisting of 150 RC structure buildings. The proposed NN-MOGA based model has been compared with Multi-layer perceptron-feed-forward network (MLP-FFN) and NN-PSO based models in terms of several performance metrics. Experimental results suggested that the NN-MOGA has outperformed other existing well known classifiers with a reasonable improvement over them. Meanwhile, the proposed NN-MOGA achieved the superior accuracy of 93.33% and F-measure of 94.44%, which is superior to the other classifiers in the present study.

Congestion management is one of the technical challenges in power system deregulation. This paper presents single objective and multi-objective optimization approaches for optimal choice, location and size of Static Var Compensators (SVC) and Thyristor Controlled Series Capacitors (TCSC) in deregulated power system to improve branch loading (minimize congestion), improve voltage stability and reduce line losses. Though FACTS controllers offer many advantages, their installation cost is very high. Hence Independent System Operator (ISO) has to locate them optimally to satisfy a desired objective. This paper presents optimal location of FACTS controllers considering branch loading (BL), voltage stability (VS) and loss minimization (LM) as objectives at once using GA. It is observed that the locations that are most favorable with respect to one objective are not suitable locations with respect to other two objectives. Later these competing objectives are optimized simultaneously considering two and three objectives at a time using multi-objective Strength Pareto Evolutionary Algorithms (SPEA). The developed algorithms are tested on IEEE 30 bus system. Various cases like i) uniform line loading ii) line outage iii) bilateral and multilateral transactions between source and sink nodes have been considered to create congestion in the system. The developed algorithms show effective locations for all the cases considered for both single and multiobjective optimization studies.

The application of the theoretical model to real assembly lines has been one of the biggest challenges for researchers and industrial engineers. There should be some realistic approach to achieve the conflicting objectives on real systems. Therefore, in this paper, a model is developed to synchronize a real system (A discrete event simulation model) with a theoretical model (An optimization model). This synchronization will enable the realistic optimization of systems. A job assignment model of the assembly line is formulated for the evaluation of proposed realistic optimization to achieve multiple conflicting objectives. The objectives, fluctuation in cycle time, throughput, labor cost, energy cost, teamwork and deviation in the skill level of operators have been modeled mathematically. To solve the formulated mathematical model, a multi-objective simulation integrated hybrid genetic algorithm (MO-SHGA) is proposed. In MO-SHGA each individual in each population acts as an input scenario of simulation. Also, it is very difficult to assign weights to the objective function in the traditional multi-objective GA because of pareto fronts. Therefore, we have proposed a probabilistic based linearization and multi-objective to single objective conversion method at population evolution phase. The performance of MO-SHGA is evaluated with the standard multi-objective genetic algorithm (MO-GA) with both deterministic and stochastic data settings. A case study of the goalkeeping gloves assembly line is also presented as a numerical example which is solved using MO-SHGA and MO-GA. The proposed research is useful for the development of synchronized human based assembly lines for real time monitoring, optimization, and control.

본 논문의 목적은 신뢰성 있는 선형회귀모델을 구축하기 위하여 후보독립변수 중 유효변수를 선택하는 알고리즘을 구현하는 것이다. 선형회귀모델을 구축하는데 있어서 데이터 상의 모든 후보독립변수를 포함하는 것은 모델의 통계적 유의성을 감소시킬 수 있으며, 차원의 저주(Curse of dimensionality)를 유발할 수 있고, 데이터의 개수보다 변수의 개수가 많을 경우 모델의 구축이 불가능한 문제점 등이 있다. 이와 같은 문제점을 해결하기 위하여 변수선택의 문제를 조합최적화의 문제로 보고 유전 알고리즘(Genetic Algorithm)을 활용하였다. 일반적으로 선형회귀모델의 통계적 유의성을 평가하는 대표적인 통계량으로는 종속변수에 대한 독립변수의 설명력을 나타내는 결정계수($R^2$), 회귀식의 통계적 유의성을 검정하는 F통계량, 회귀계수의 통계적 유의성을 검정하는 t통계량, 잔차의 표준오차 등이 있다. 모델의 통계적 유의성은 하나의 통계량으로 표현될 수 없으므로 다양한 기준을 고려한 다중목적식(Multi-objective function)을 가지는 유전 알고리즘을 설계하였다. 설계한 알고리즘의 성능평가를 위하여 다양한 조건을 가정한 시뮬레이션 데이터에 적용하였다. 그 결과 구축한 알고리즘이 유효변수를 판단함에 있어 기존의 대표적인 변수선택 알고리즘인 LARS(Least Angle Regression)에 비해 우수한 성능을 보임을 확인할 수 있었다. 또한, 주가 데이터를 이용한 포트폴리오 선택에 적용해 본 결과 우수한 응용문제 해결 능력이 있음을 확인할 수 있었다.

The purpose of this study is to implement variable selection algorithm which helps construct a reliable linear regression model. If we use all candidate variables to construct a linear regression model, the significance of the model will be decreased and it will cause 'Curse of Dimensionality'. And if the number of data is less than the number of variables (dimension), we cannot construct the regression model. Due to these problems, we consider the variable selection problem as a combinatorial optimization problem, and apply GA (Genetic Algorithm) to the problem. Typical measures of estimating statistical significance are $R^2$, F-value of regression model, t-value of regression coefficients, and standard error of estimates. We design GA to solve multi-objective functions, because statistical significance of model is not to be estimated by a single measure. We perform experiments using simulation data, designed to consider various kinds of situations. As a result, it shows better performance than LARS (Least Angle Regression) which is an algorithm to solve variable selection problems. We modify algorithm to solve portfolio selection problem which construct portfolio by selecting stocks. We conclude that the algorithm is able to solve real problems.

무선 센서 & 액터 네트워크(WSAN)와 같이 다수의 베이스 노드가 존재하거나 베이스 노드의 이동성이 큰 센서 네트워크에서 최소 Wiener수 신장 트리(MWST)기반 라우팅 방법은 최소 신장 트리(MST)기반 라우팅 방법에 비해 패킷 전송 거리가 짧고 전력 소모가 적다. 하지만 주어진 그래프로부터 최소 Wiener 수 신장 트리를 찾는 문제는 NP-hard 문제이고 최소 신장 트리에 비해 네트워크 수명이 짧은 단점이 있다. 본 논문은 이러한 문제를 해결하고자 Wiener 수 적응도, 네트워크 수명 적응도, 차수 적응도 등을 동시에 고려한 다목적 유전자 알고리즘을 설계하고 네트워크 전체 전력 소모를 크게 증가시키지 않으면서도 네트워크의 수명을 Wiener 수 적응도만을 사용했을 때 보다 연장시킴을 실험을 통해 보인다.