• 전기전자학회논문지
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• 제11권3호
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• pp.100-107
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• 2007

무선 센서 네트워크에서 중요한 문제 중 하나는 센서 노드들의 최적 배치, 즉 측정하고자 하는 지역을 모두 커버할 수 있는 최소 센서 노드 수를 산출하고 배치 위치를 결정하는 일이다. 본 논문에서는 이러한 문제를 해결하기 위한 방법으로 제안한 Fuzzy C-Means 클러스터링을 이용하여 측정하고자 하는 지역에서의 최적의 노드 배치와 최소 노드의 수를 시뮬레이션을 통해 도출하였고, 실험을 통하여 검증하였다. 시뮬레이션은 3가지 타입의 2차원 지역을 모델로 하여 수행하였다. 모델링한 지역은 6M${\times}$10M의 직사각형, 50M${\times}$20M의 직사각형, 100M${\times}$80M의 ‘L’ 자 형태의 지역으로 하였으며, 각각 9개, 9개, 15개 노드의 위치를 결정하였다. 실제 실험결과 각 지역에 대해서 94.6%, 92.2%, 95.7%의 정확도를 가진 통신 연결을 확인할 수 있었다.

• Corrosion Science and Technology
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• 제7권4호
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• pp.197-200
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• 2008

In this paper, physical scale modeling was employed to identify the configurations of ICCP system and the electric field signatures. Computational boundary element modeling technique has been used to simulate the performance of the CP system and to predict the associated electric fields signatures. The optimization methods combined with the computer models and physical scale modeling will be presented here, which enable the optimum system design to be achieved both in terms of the location and current output of the anode but also in the location of reference electrodes for impressed current cathodic protection(ICCP) systems. The combined methodology was utilized to determine optimal placement of ICCP components (anodes and reference electrodes) and to evaluate performance of ICCP system for the 2%, 10% and 14% wetted hull coatings loss. The objective is to design the system to minimise the electric field while at the same time provide adequate protection for the ship. The results show that experimental scale modeling and computational modeling techniques can be used in concert to design an optimum ICCP system and to provide information for quickly analysis of the system and its surrounding environment.

• Structural Engineering and Mechanics
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• 제81권6호
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• pp.677-689
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• 2022

Generally, the goal of seismic retrofit design of an existing structure using energy dissipation devices is to determine the optimum design parameters of a retrofit device to satisfy a specified limit state with minimum cost. However, the presence of multiple parameters to be optimized and the computational complexity of performing non-linear analysis make it difficult to find the optimal design parameters in the realistic 3D structure. In this study, genetic algorithm-based optimal seismic retrofit methods for determining the required number, yield strength, and location of steel slit dampers are proposed to retrofit an asymmetric soft first-story structure. These methods use a multi-objective and single-objective evolutionary algorithms, each of which varies in computational complexity and incorporates nonlinear time-history analysis to determine seismic performance. Pareto-optimal solutions of the multi-objective optimization are found using a non-dominated sorting genetic algorithm (NSGA-II). It is demonstrated that the developed multi-objective optimization methods can determine the optimum number, yield strength, and location of dampers that satisfy the given limit state of a three-dimensional asymmetric soft first-story structure. It is also shown that the single-objective distribution method based on minimizing plan-wise stiffness eccentricity turns out to produce similar number of dampers in optimum locations without time consuming nonlinear dynamic analysis.

• 전자공학회논문지
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• 제52권3호
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• pp.13-18
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• 2015

본 논문은 GNSS의 문제점인 위치오차와 실외음영지역을 해소하기 위하여 GNSS와 vision system을 융합한 신뢰성있는 고정밀 측위와 최적의 vision system을 분석하였다. 위치결정을 위해서는 최소 4개 이상의 GNSS로부터 신호를 수신 받아야 한다. 그러나 도심지역에서는 고층건물이나 장애물 또는 반사파에 의해 정확한 위치가 어렵다. 이러한 문제점을 해결하기 위하여 vision system을 이용한다. GNSS를 사용하기 열악한 도심지역의 target object에 정확한 위치 값을 결정해 놓는다. 그리고 vision system을 이용해 target object를 인식하고, 인식된 target object를 이용하여 위치오차를 보정해 준다. 이동체는 이동 중 vision system을 이용하여 target object를 인식하여 위치 데이터 값을 만들어내고, 위치 계산을 수정하여 안정되고 신뢰성 있는 고정밀 측위를 할 수 있다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.672-679
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• 2005

Damage detection is a very active research field, in which significant efforts have been invested in recent years. In this paper, analysis using structural stiffness estimation for damage detection is presented and compared to other methodologies. By using a cantilever analytical beam model, it is shown here that not only location but also the amount of damage in structure can be predicted from the ratio of change in stiffness. Damage detection experiment in real beam specimen on is also peformed and the results are compared.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.61-64
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• 2005

The purpose of this paper is to take a closer look at an area having shorted emergence facilities and to determine optional candidate sites instead of vulnerable area by using GIS spatial analysis. Newly determined new candidate is performed by concerning spatial efficiency and spatial equity for a public service. It was determined through using the analyzing of the physical accessibility measure, the Location-Allocation, sort of classic model in spatial statistics and general network analysis. The area of this research has been used in administrative boundary of Young-Dong in Gangneung including 13 emergency, medical hospitals, 46 fire-stations and sub-fire stations. In general terms, what all this show is that the way we are approached for geographical view from using GIS spatial analyzing technique of determined location and allocation problem by the social, economical, political factor and simple administrative discrimination at the meantime. At the same time, with problem occurred in the space it is possible to make an Effective proposal or means, policy, decision for new candidate location-allocation suggesting optimum model.

• Journal of Welding and Joining
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• 제15권3호
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• pp.109-117
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• 1997

The temperature gradient in weldment changes the transit time and distorts the direction of the ultrasound beam to the higher temperature regions due to the lower sound speed in the hotter regions of the weldment. This paper describes a ray-tracing method for calculating the effects of temperature gradients on ultrasonic propagation in fillet arc weldig. In the method, weldment is conceptually devided into a number of layers and the refraction and sound speed at each layer is calculated using the temperature which calculated from analytical solution. Calculating the time and location of echoes arrived from various interfaces around a molten weld pool determines the optimum location of ultrasonic transducers and the correct position of flaws.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.405-410
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• 2006

This paper presents a control algorithm of supply and exhaust diffusers by recognizing a contaminant source location. CFD analysis has been conducted to calculate steady state airflow and concentration distributions in a model room, which has two supply and two exhaust openings on the ceiling. Calculations have been performed for five cases out of nine different ventilation modes by combining on/off control of the supply and exhaust openings. Local mean residual life times are obtained and compared at 9 internal points for each ventilation case. Depending on the contaminant source location, the ventilation system is operated at an optimum ventilation mode, which can results in maximum exhaust performance.

• 한국철도학회논문집
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• 제9권1호
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• pp.102-109
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• 2006

The PSC girders which currently used at highway bridge have the standard cross sections about 25m, 30m and 35m span. Thus, in case of highway bridge design, the bridge designer can choose the adequate standard cross section according to constructional condition. However, in railway bridge design, there are limitations on reasonable bridge design considering circumstances of a construction site and conditions of location etc, because the PSC girders used at railway bridge have the cross section about only 25m span length. In this study, the optimum design for the PSC girder railway bridge with 30m span length has been performed. Also, in order to investigate the dynamic stability of railway bridge using the optimum section of PSC girder, dynamic analysis has been carried out. From the results of analysis, it is suggested to denote the optimum section which satisfied the structural safety, dynamic stability and economical efficiency all together.

• 대한전기학회논문지
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• 제40권5호
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• pp.453-459
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• 1991

This paper presents a new algorithm to select optimal parameters and location of power system stabilizer (PSS). A new performance measure, which evaluates the share of a particular mode among state responses, is introduced. The gradient of the performance measure with respect to PSS parametes is derived in an explicit form, so optimal parameters of PSS can be obtained by the steepest descent method. The machine, with which it is most probable to reduce the performance measure, is identified as the optimum site for PSS application.