• 상하수도학회지
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• 제30권5호
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• pp.491-500
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• 2016

Pressure monitoring is expected to be expanded in a water distribution system according to accelerated development of smart water network management technologies caused by appearances of affordable digital infrastructures like computing, storage and bandwidth. However, the placement of pressure sensors has been determined by engineer's technical decisions since there is no well-defined criteria for deciding a suitable location of pressure sensor. This study presents a placement method of pressure sensors based on the consideration of allowable error in calibrating water network analysis modeling. The proposed method is to find a minimum set of pressure sensors for achieving a reliable management of water transmissions main and increasing the efficiency of their real-time operation. In the case study in Y area's transmission main, the proposed method shows equally distributed pressure sensors in terms of hydraulics. It is expected that the proposed method can be used to manage transmission mains stably and construct a robust real-time network analysis system as a minimal criteria.

• Smart Structures and Systems
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• 제31권6호
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• pp.545-559
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• 2023

Nanoparticle strips (NPS) are widely used as external reinforcers for two-way reinforced concrete slabs. However, the Structural Health Monitoring (SHM) of these slabs is a very important issue and was evaluated in this study. This study has been done analytically and numerically to optimize the placement of sensors. The properties of slabs and carbon nanotubes as composite sheets were considered isotopic and orthotropic, respectively. The nonlinear Finite Element Method (FEM) approach and suitable optimal placement of sensor approach were developed as a new MATLAB toolbox called DECOMAC by the authors of this paper. The Suitable multi-objective function was considered in optimized processes based on distributed ECOMAC method. Some common concrete slabs in construction with different aspect ratios were considered as case studies. The dimension and distance of nano strips in retrofitting process were selected according to building codes. The results of Optimal Sensor Placement (OSP) by DECOMAC algorithm on un-retrofitted and retrofitted slabs were compared. The statistical analysis according to the Mann-Whitney criteria shows that there is a significant difference between them (mean P-value = 0.61).

• 대한공간정보학회지
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• 제18권2호
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• pp.3-12
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• 2010

최근 항공사진과 고해상도 위성영상의 보급과 수치사진측량 시스템 및 분석 알고리즘의 발전으로 인하여 데이터 추출, 영상이미지프로세싱처리, 정밀 대축척지도제작 등의 연구가 진행되고 있지만 2차원 평면 정보라는 제한적인 요소를 가지고 있다. 이에, 높은 위치정확도와 개체인식을 위한 정확한 공간정보와 3차원 좌표가 필요하게 되었다. 본 연구에서는 높은 위치정확도가 검증된 LiDAR의 3차원 공간정보를 이용하여 실제 지형을 반영하였고, 센서 최적 위치를 도출하기위해 확률알고리즘을 개발하고 공간분석을 통해 확률 값을 산정하였다. Grid기반인 2차원 3차원 센서위치지점을 생성하고 LiDAR의 3차원정보를 센서감지영역 산정에 적용하였다. 이 데이터를 바탕으로 알고리즘을 구현하여 최적 센서위치지점으로 선정하였다. 또한 최적 센서위치지점 선정 시 고려사항을 3가지 조건으로 나누었다. 첫째조건은 방해물이 없는 2차원인 경우(2-D Non obstacle), 둘째조건은 방해물이 존재하는 2차원인 경우(2-D Obstacle), 셋째는 방해물이 존재하며 3차원인 조건(3-D Obstacle)으로 설정하였다. 이 3가지 조건에 알고리즘을 적용하여 2차원, 3차원적 공간에 대한 최적위치선정 방법을 검토하였다. 결론적으로 본 연구에서는 LiDAR 데이터를 이용하여 정보 수집을 위한 지상 고정센서 위치 선정 방법론을 제시하고자 하였다.

• Smart Structures and Systems
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• 제15권1호
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• pp.191-207
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• 2015

Proper placement of sensors plays a key role in construction and implementation of an effective structural health monitoring (SHM) system. This paper proposes a novel methodology called the distributed monkey algorithm (DMA) for the optimum design of SHM system sensor arrays. Different from the existing algorithms, the dual-structure coding method is adopted for the representation of design variables and the single large population is partitioned into subsets and each subpopulation searches the space in different directions separately, leading to quicker convergence and higher searching capability. After the personal areas of all subpopulations have been finished, the initial optimal solutions in every subpopulation are extracted and reordered into a new subpopulation, and the harmony search algorithm (HSA) is incorporated to find the final optimal solution. A computational case of a high-rise building has been implemented to demonstrate the effectiveness of the proposed method. Investigations have clearly suggested that the proposed DMA is simple in concept, few in parameters, easy in implementation, and could generate sensor configurations superior to other conventional algorithms both in terms of generating optimal solutions as well as faster convergence.

• Smart Structures and Systems
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• 제26권6호
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• pp.721-733
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• 2020

The present study investigates the employing of piezoelectric patches in active control of a sandwich plate. Indeed, the active control and optimal patch distribution on this structure are presented together. A sandwich plate with honeycomb core and composite reinforced by carbon nanotubes in facesheet layers is considered so that the optimum position of actuator/sensor patches pair is guaranteed to suppress the vibration of sandwich structures. The sandwich panel consists of a search space which is a square of 200 × 200 mm with a numerous number of candidates for the optimum position. Also, different dimension of square and rectangular plates to obtain the optimal placement of piezoelectric actuator/senor patches pair is considered. Based on genetic algorithm and LQR, the optimum position of patches and fitness function is determined, respectively. The present study reveals that the efficiency and performance of LQR control is affected by the optimal placement of the actuator/sensor patches pair to a large extent. It is also shown that an intelligent selection of the parent, repeated genes filtering, and 80% crossover and 20% mutation would increase the convergence of the algorithm. It is noted that a fitness function is achieved by collection actuator/sensor patches pair cost functions in the same position (controllability). It is worth mentioning that the study of the optimal location of actuator/sensor patches pair is carried out for different boundary conditions of a sandwich plate such as simply supported and clamped boundary conditions.

• Structural Engineering and Mechanics
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• 제37권6호
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• pp.671-684
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• 2011

Deciding on an optimal sensor placement (OSP) is a common problem encountered in many engineering applications and is also a critical issue in the construction and implementation of an effective structural health monitoring (SHM) system. The present study focuses with techniques for selecting optimal sensor locations in a sensor network designed to monitor the health condition of Dalian World Trade Building which is the tallest in the northeast of China. Since the number of degree-of-freedom (DOF) of the building structure is too large, multi-modes should be selected to describe the dynamic behavior of a structural system with sufficient accuracy to allow its health state to be determined effectively. However, it's difficult to accurately distinguish the translational and rotational modes for the flexible structures with closely spaced modes by the modal participation mass ratios. In this paper, a new method of the OSP that computing the mode shape matrix in the weak axis of structure by the simplified multi-DOF system was presented based on the equivalent rigidity parameter identification method. The initial sensor assignment was obtained by the QR-factorization of the structural mode shape matrix. Taking the maximum off-diagonal element of the modal assurance criterion (MAC) matrix as a target function, one more sensor was added each time until the maximum off-diagonal element of the MAC reaches the threshold. Considering the economic factors, the final plan of sensor placement was determined. The numerical example demonstrated the feasibility and effectiveness of the proposed scheme.

• Smart Structures and Systems
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• 제2권2호
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• pp.189-208
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• 2006

Monitoring large-scale civil engineering structures such as offshore platforms and high-large buildings requires a large number of sensors of different types. Innovative sensor data information technologies are very extremely important for data transmission, storage and retrieval of large volume sensor data generated from large sensor networks. How to obtain the optimal sensor set and placement is more and more concerned by researchers in vibration-based SHM. In this paper, a method of determining the sensor location which aims to extract the dynamic parameter effectively is presented. The method selects the number and place of sensor being installed on or in structure by through the tolerance domain statistical inference algorithm combined with second order sensitivity technology. The method proposal first finds and determines the sub-set sensors from the theoretic measure point derived from analytical model by the statistical tolerance domain procedure under the principle of modal effective independence. The second step is to judge whether the sorted out measured point set has sensitive to the dynamic change of structure by utilizing second order characteristic value sensitivity analysis. A 76-high-building benchmark mode and an offshore platform structure sensor optimal selection are demonstrated and result shows that the method is available and feasible.

• Smart Structures and Systems
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• 제16권2호
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• pp.243-262
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• 2015

Optimal sensor placement (OSP) is a critical issue in construction and implementation of a sophisticated structural health monitoring (SHM) system. The uncertainties in the identified structural parameters based on the measured data may dramatically reduce the reliability of the condition evaluation results. In this paper, the information entropy, which provides an uncertainty metric for the identified structural parameters, is adopted as the performance measure for a sensor configuration, and the OSP problem is formulated as the multi-objective optimization problem of extracting the Pareto optimal sensor configurations that simultaneously minimize the appropriately defined information entropy indices. The nondirective movement glowworm swarm optimization (NMGSO) algorithm (based on the basic glowworm swarm optimization (GSO) algorithm) is proposed for identifying the effective Pareto optimal sensor configurations. The one-dimensional binary coding system is introduced to code the glowworms instead of the real vector coding method. The Hamming distance is employed to describe the divergence of different glowworms. The luciferin level of the glowworm is defined as a function of the rank value (RV) and the crowding distance (CD), which are deduced by non-dominated sorting. In addition, nondirective movement is developed to relocate the glowworms. A numerical simulation of a long-span suspension bridge is performed to demonstrate the effectiveness of the NMGSO algorithm. The results indicate that the NMGSO algorithm is capable of capturing the Pareto optimal sensor configurations with high accuracy and efficiency.

• Structural Monitoring and Maintenance
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• 제4권1호
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• pp.53-68
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• 2017

The response sensitivity method in time domain has been applied extensively for damage identification. In this paper, the relationship between the error of damage identification and the sensitivity matrix is investigated through perturbation analysis. An index is defined according to the perturbation amplify effect and an optimal sensor placement method is proposed based on the minimization of that index. A sequential sub-optimal algorithm is presented which results in consistently good location selection. Numerical simulations with a two-dimensional high truss structure are conducted to validate the proposed method. Results reveal that the damage identification using the optimal sensor placement determined by the proposed method can identify multiple damages of the structure more accurately.

• 한국ITS학회 논문지
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• 제8권5호
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• pp.26-37
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• 2009

본 연구에서는 USN 환경하에서 다수 개의 지점교통센서를 신호교차로의 접근로에 설치되어 운전자 안전서비스를 제공할 경우 딜레마구간 검지를 위한 센서의 배치 방법에 대하여 다룬다. 교통 신호가 녹색-황색-적색으로 변동되는 시점에서 딜레마구간에 존재하는 위험차량을 검지하는 시스템에서, 센서의 배치 간격과 초기 위치를 확인하기 위해 미시적 시뮬레이션인 VISSIM을 이용하여 평가하였다. VISSIM에 지점검지기를 다수 개 설치하여 유입교통량의 변화, 설계속도의 변화, 운전자 인지반응시간의 변화를 수행하였다. 그 결과 지점교통센서는 20~27m의 간격으로, 도로의 설계속도에 따라 초기 센서의 위치를 변화하여 설치할 필요성이 있음을 알 수 있었다. 또한 교통량의 변화에 따라 센서의 딜레마구간 검지추세가 다름을 알 수 있었다. 본 연구로 미시적 교통시뮬레이션 기반으로 지점교통센서의 배치를 평가하는 방법의 유용성을 확인할 수 있었고, 향후 USN 서비스의 실현에 있어 기초 자료로 사용될 수 있음을 알 수 있었다.