• 설비공학논문집
• /
• 제18권8호
• /
• pp.635-640
• /
• 2006

An optimizer has been applied for the optimal design of pipe diameters in the pipe flow network problems. Pipe network flow analysis, which is developed separately, is performed within the interface for the optimization algorithm. A pipe network is chosen for the test, and optimizer GenOpt is applied with Holder-Mead-O'Niell's simplex algorithm after solving the network flow problem by the Newton-Raphson method. As a result, optimally do-signed pipe diameters are successfully obtained which minimize the total design cost. Design cost of pipe flow network can be considered as the sum of pipe installation cost and pump operation cost. In this study, a practical and efficient solution method for the pipe network optimization is presented. Test system is solved for the demonstration of the present optimization technique.

• Membrane and Water Treatment
• /
• 제10권1호
• /
• pp.75-82
• /
• 2019

In a highly urbanized area, land availability is limited for the installation of space consuming stormwater systems for best management practices (BMPs), leading to the consideration of underground stormwater treatment devices connected to the stormwater pipe system. The configuration of a stormwater pipe network determines the hydrological and pollutant transport characteristics of the stormwater discharged through the pipe network, and thus should be an important design consideration for effective management of stormwater quantity and quality. This article presents a multi-objective optimization approach for designing a stormwater pipe network with on-line stormwater treatment devices to achieve an optimal trade-off between the total installation cost and the annual removal efficiency of total suspended solids (TSS). The Non-dominated Sorted Genetic Algorithm-II (NSGA-II) was adapted to solve the multi-objective optimization problem. The study site used to demonstrate the developed approach was a commercial area that has an existing pipe network with eight outfalls into an adjacent stream in Yongin City, South Korea. The stormwater management model (SWMM) was calibrated based on the data obtained from a subcatchment within the study area and was further used to simulate the flow rates and TSS discharge rates through a given pipe network for the entire study area. In the simulation, an underground stormwater treatment device was assumed to be installed at each outfall and sized proportional to the average flow rate at the outfall. The total installation cost for the pipes and underground devices was estimated based on empirical formulas using the flow rates and TSS discharge rates simulated by the SWMM. In the demonstration example, the installation cost could be reduced by up to 9% while the annual TSS removal efficiency could be increased by 4% compared to the original pipe network configuration. The annual TSS removal efficiency was relatively insensitive to the total installation cost in the Pareto-optimal solutions of the pipe network design. The results suggested that the installation cost of the pipes and stormwater treatment devices can be substantially reduced without significantly compromising the pollutant removal efficiency when the pipe network is optimally designed.

• Water Engineering Research
• /
• 제1권1호
• /
• pp.63-74
• /
• 2000

This paper presents a two- phase search scheme for optimal pipe expansion of expansion of existing water distribution systems. In pipe network problems, link flows affect the total cost of the system because the link flows are not uniquely determined for various pipe diameters. The two-phase search scheme based on stochastic optimization scheme is suggested to determine the optimal link flows which make the optimal design of existing pipe network. A sample pipe network is employed to test the proposed method. Once the best tree network is obtained, the link flows are perturbed to find a near global optimum over the whole feasible region. It should be noted that in the perturbation stage the loop flows obtained form the sample existing network are employed as the initial loop flows of the proposed method. It has been also found that the relationship of cost-hydraulic gradient for pipe expansion of existing network affects the total cost of the sample network. The results show that the proposed method can yield a lower cost design than the conventional design method and that the proposed method can be efficiently used to design the pipe expansion of existing water distribution systems.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2023년도 학술발표회
• /
• pp.169-169
• /
• 2023

Most distributed water is not used effectively due to water loss occurring in pipe networks. These water losses are caused by leakage, typically due to high water pressure to ensure adequate water supply. High water pressure can cause the pipe to burst or develop leaks over time, particularly in an aging network. In order to reduce the amount of leakage and ensure proper water distribution, it is important to apply pressure management. Pressure management aims to maintain a steady and uniform pressure level throughout the network, which can be achieved through various operational schemes. The schemes include: (1) installing a variable speed pump (VSP), (2) introducing district metered area (DMA), and (3) operating pressure-reducing valves (PRV). Applying these approaches requires consideration of various hydraulic, economic, and environmental aspects. Due to the different functions of these approaches and related components, an all-together optimization of these schemes is a complicated task. In order to reduce the optimization complexity, this study recommends a sequential optimization method. With three network operation schemes considered (i.e., VSP, DMA, and PRV), the method explores all the possible combinations of pressure management paths. Through sequential optimization, the best pressure management path can be determined using a multiple-criteria decision analysis (MCDA) to weigh in factors of cost savings, investment, pressure uniformity, and CO₂ emissions. Additionally, the contribution of each scheme to pressure management was also described in the application results.

• Korean Chemical Engineering Research
• /
• 제46권3호
• /
• pp.598-603
• /
• 2008

석유화학산업단지의 수소 네트워크 최적화는 석유화학산업 단지 내 각 업체 간 잉여 수소와 필요 수소의 양과 순도를 조사하여 최적의 분배를 구해는 것이다. 본 논문에서는 새로운 네트워크를 구성할 때 기존의 파이프라인을 고려한다면 비용을 줄일 수 있는 효과를 정량적으로 명확하게 알아보기 위해 가상의 수소 네트워크를 구성하여 기존의 파이프라인을 활용하는 것과 활용하지 않는 두 가지의 case를 모델링하고 수리계획법을 사용하여 계산, 비교해 보았다. 그 결과 기존의 파이프라인을 활용한다면 가정된 조건 하 에서 파이프비용을 20%이상 줄이고 전체네트워크 이익을 약 14억 원 증가시키는 결과를 얻을 수 있었다.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2021년도 학술발표회
• /
• pp.145-145
• /
• 2021

Water distribution networks (WDNs) are designed to satisfy water requirement of an urban community. One of the central issues in human history is providing sufficient quality and quantity of water through WDNs. A WDN consists of a great number of pipelines with different ages, lengths, materials, and sizes in varying degrees of deterioration. The available annual budget for rehabilitation of these infrastructures only covers part of the network; thus it is important to manage the limited budget in the most cost-effective manner. In this study, a novel pipe replacement scheduling approach is proposed in order to smooth the annual investment time series based on a life cycle cost assessment. The proposed approach is applied to a real WDN currently operating in South Korea. The proposed scheduling plan considers both the annual budget limitation and the optimum investment on pipes' useful life. A non-dominated sorting genetic algorithm is used to solve a multi-objective optimization problem. Three decision-making objectives, including the minimum imposed LCC of the network, the minimum standard deviation of annual cost, and the minimum average age of the network, are considered to find optimal pipe replacement planning over long-term time period. The results indicate that the proposed scheduling structure provides efficient and cost-effective rehabilitation management of water network with consistent annual budget.

• 한국가스학회지
• /
• 제1권1호
• /
• pp.56-63
• /
• 1997

본 연구에서는 실제현장에 활용할 수 있는 가스파이프라인 네트워크의 최적화 모델을 개발하기 위해 먼저 구조 설계에 있어서 네트워크 알고리즘 중 MCST(Minimum Cost Spanning Tree) 알고리즘을 도입하여 전반적인 구조를 결정하고, 기존 방법의 단점을 보완하기 위해 Constrained Derivative 방법을 적용하였다. 또한 모델 개발 시, 압축기$\cdot$밸브등의 갑작스런 운전상태의 변화와 파이프의 파열 둥으로 인한 유동저해 현상을 예측할 수 있는 파이프라인 해석모델과 연계할 수 있도록 고려하여 설계하였다. 각 절점과 간선간의 압력 및 유량, 즉 파이프라인 배관망에서 필요한 수요량을 적절히 공급할 수 있는 파이프라인 망의 직경과 길이를 최소의 비용으로 결정하는 복합형 파이프라인 네트워크 최적설계 모델을 개발하였다 개발된 모델을 전형적인 천연가스 파이프라인 네트워크에 적용하여 최적설계를 수행한 결과, 보다 작은 파이프 직경과 낮은 절점 압력으로도 각 절점에서의 수요량을 공급할 수 있도록 설계할 수 있었으며, 원래의 시스템과 비교하여 약 $40\%$정도의 비용 절감효과를 볼 수 있었다. 또한, 기존의 국내 수도권 배관망에 대해 본 모델을 적용하여 새로운 설계모형을 제안함으로써 초기설계나 향우 추가 확장되는 부분의 배관망에 대해서도 경제성을 고려하여 최소비용의 네트워크 구성을 할 수 있음을 확인하였다.

• 대한산업공학회지
• /
• 제10권2호
• /
• pp.17-27
• /
• 1984

This paper is concerned with a branched pipe network system which transports some fluids or gas from multiple sources to multiple demand nodes. A nonlinear programming model is proposed for determining junction locations simultaneously with selection of pipe sizes and pump capacities such that the capital and operating costs of the system are minimized over a given planning horizon. To solve the model, a hierarchical decomposition method is developed with the junction location being the primary variable. With some values fixed for the primary, the other decision variables are found by linear programming. Then, using the postoptimality analysis of LP, junction locations are adjusted. We repeat this process until an optimum is approached. A simple example of designing a water distribution network is solved to illustrate the optimization procedure developed.

• 한국수자원학회논문집
• /
• 제32권1호
• /
• pp.71-81
• /
• 1999

본 연구의 목적은 유전자 알고리즘 최적화기법을 이용하여 설계기준에 합당한 제약조건을 고려한 최소경비의 관망시스템의 설계를 목적으로 한다. 수리학적 제약조건들은 수리모의프로그램(KYPIPE)과 연계하여 가능해 영역을 수시로 검증하였다. 유전자 알고리즘은 비교적 새로운 최적화기법이다. 유전자 알고리즘은 매우 강력한 탐색능력을 가지고 있으며 특히 비선형 문제를 해결하는데 탁월한 성능을 가진다고 알려져 있다. 유전자 알고리즘은 계산결과로 제시되는 결정변수인 관경은 연속적인 수치가 아닌 이산적인 규격의 표준관경인 상업용 관경으로 제시되며 펌프용량까지 최적화시키는 효율적인 최적설계를 도모하고자 한다. 본 모형은 가상 및 실제 관망시스템에 적용하였다. 그 중 하나는 많은 다른 연구자들에 의한 간단한 관망에 사용된 논문들로부터 채택하였다. 그 결과의 비교는 이 연구에서 개발된 모형의 적합성을 보여준다. 또한, 본 모형은 최적펌프용량도 결정할 수 있으며 그 적용성을 검증하기 위하여 고양시에 적용시켜 보았다. 개발된 모형은 비교적 간단한 방법으로 관망시스템의 최적설계에 성공적으로 적용시킬 수 있음이 판명되어져 왔다.

• 한국수자원학회논문집
• /
• 제31권3호
• /
• pp.327-335
• /
• 1998

상수관망은 상수공급시스템에서 핵심적인 부분이다. 주어진 상수공급시스템에서 배수관망에 대한 비용은 사업전체 비용에 대한 대부분을 차지하고 있다. 관망에 대한 설계과정 중에서 최적화기법을 사용하여 비용을 절감하기 위한 연구가 시도되었다. 주어진 상수관망 시스템의 설계시 고려되는 관경의 결정을 위해 유량해석과 최적화 기법이 연계되어 해석하는 반복기법이 적용되었다. 유량해석을 위해서 선형화기법이 되입되었고 관경의 최적화를 위해서 선형계획법에 기초한 개정 단체법을 이용하였다. 22개 관로와 35개 관로를 가진 실제관망에 본 모형을 적용한 결과 짧은 계산시간으로 최적화된 상용관을 결정할 수 있었다.