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

• Smart Structures and Systems
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• 제14권1호
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• pp.39-54
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• 2014

Node layout optimization of structural wireless systems is investigated as a means to prolong the network lifetime without, if possible, compromising information quality of the measurement data. The trade-off between these antagonistic objectives is studied within a multi-objective layout optimization framework. A Genetic Algorithm is adopted to obtain a set of Pareto-optimal solutions from which the end user can select the final layout. The information quality of the measurement data collected from a heterogeneous WSN is quantified from the placement quality indicators of strain and acceleration sensors. The network lifetime or equivalently the network energy consumption is estimated through WSN simulation that provides realistic results by capturing the dynamics of the wireless communication protocols. A layout optimization study of a monitoring system on the Great Belt Bridge is conducted to evaluate the proposed approach. The placement quality of strain gauges and accelerometers is obtained as a ratio of the Modal Clarity Index and Mode Shape Expansion values that are computed from a Finite Element model of the monitored bridge. To estimate the energy consumption of the WSN platform in a realistic scenario, we use a discrete-event simulator with stochastic communication models. Finally, we compare the optimization results with those obtained in a previous work where the network energy consumption is obtained via deterministic communication models.

• 한국공간구조학회논문집
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• 제10권4호
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• pp.93-102
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• 2010

본 연구에서는 MR 감쇠기와 FPS를 사용하여 구성된 스마트 스카이브릿지를 제안하였으며 스마트 스카이브릿지로 연결된 인접건물의 지진응답 제어성능을 분석하였다. 이를 위하여 스마트 스카이브릿지로 연결된 10층과 20층 구조물을 예제 구조물로 선택하였고 근거리 (near fault) 및 원거리 (far fault) 지진의 특성을 가지는 El Centro 지진과 Kobe지진을 사용하여 시간이력해석을 수행하였다. 스마트 스카이브릿지블 효과적으로 제어하기 위해서 퍼지논리제어기를 개발하였으며 퍼지논리제어기를 최적화하기 위하여 다목적 유전자알고리즘을 사용하였다. 최적화결과 10층 건물의 지진응답과 20층 건물의 지진응답 사이에는 상충관계 (trade-off)가 있는 것을 알 수 있었고 다목적 유전자알고리즘을 통해서 두 건물의 지진응답 제어에 대한 퍼지논리제어거의 파레토 해집합을 구할 수 있었다. 수치해석결과 본 연구에서 제안한 스마트 스카이브릿지를 사용하면 연결된 건물의 지진응답을 효율적으로 저감시킬 수 있는 것을 알 수 있었다.

• Wind and Structures
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• 제29권5호
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• pp.323-337
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• 2019

Wind tunnel testing technique has been established as a powerful experimental method for predicting wind-induced loads on high-rise buildings. Accurate assessment of the design wind load combinations for tall buildings on the basis of wind tunnel tests is an extremely important and complicated issue. The traditional design practice for determining wind load combinations relies partly on subjective judgments and lacks a systematic and reliable method of evaluating critical load cases. This paper presents a novel optimization-based framework for determining wind tunnel derived load cases for the structural design of wind sensitive tall buildings. The peak factor is used to predict the expected maximum resultant responses from the correlated three-dimensional wind loads measured at each wind angle. An optimized convex hull is further developed to serve as the design envelope in which the peak values of the resultant responses at any azimuth angle are enclosed to represent the critical wind load cases. Furthermore, the appropriate number of load cases used for design purposes can be predicted based on a set of Pareto solutions. One 30-story building example is used to illustrate the effectiveness and practical application of the proposed optimization-based technique for the evaluation of peak resultant wind-induced load cases.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2006년도 춘계 국제학술대회 논문집
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• pp.95-108
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• 2006

본 논문은 수출입 컨테이너 화물의 국제물류에 대한 최적의 복합운송 경로를 도출하기 위한 동적 프로그램 알고리즘을 제시한다. 현재 3자물류 시장의 급부상, 운송업계의 경쟁가열화, 운송경로의 다양화 및 글로벌화가 추구되면서 복합운송을 고려한 수송계획의 효율화가 필요한 실정이다. 그러므로 2가지 이상의 운송수단을 이용하는 복합운송의 특징을 살펴보고, 운송비용과 운송시간을 고려한 WCSPP(Weighted Constrained Shortest Path Problem) 모형을 제시한다. 본 모형을 통해 도출된 목적함수 결과값을 이용하여 실행가능영역을 설정한 뒤, 동적 프로그래밍(Dynamic Programming)중 하나인 Label Setting 알고리즘을 응용하여, 두가지 목적함수를 동시에 만족할 수 있는 파레토 최적해를 도출하였다. 또한 본 알고리즘의 성능을 향상시키기 위해 가지치기 규칙을 함께 제안한다. 본 알고리즘을 부산에서 출발하여 로테르담까지 도착하는 실제 운송경로에 적용하였으며, 단일운송수단 및 기존의 복합운송 경로와 비교해 봄으로써 운송비용 및 운송시간의 절감효과를 정량적으로 측정하였다.