• Title/Summary/Keyword: grid size

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Development of Intelligent ATP System Using Genetic Algorithm (유전 알고리듬을 적용한 지능형 ATP 시스템 개발)

  • Kim, Tai-Young
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.131-145
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    • 2010
  • The framework for making a coordinated decision for large-scale facilities has become an important issue in supply chain(SC) management research. The competitive business environment requires companies to continuously search for the ways to achieve high efficiency and lower operational costs. In the areas of production/distribution planning, many researchers and practitioners have developedand evaluated the deterministic models to coordinate important and interrelated logistic decisions such as capacity management, inventory allocation, and vehicle routing. They initially have investigated the various process of SC separately and later become more interested in such problems encompassing the whole SC system. The accurate quotation of ATP(Available-To-Promise) plays a very important role in enhancing customer satisfaction and fill rate maximization. The complexity for intelligent manufacturing system, which includes all the linkages among procurement, production, and distribution, makes the accurate quotation of ATP be a quite difficult job. In addition to, many researchers assumed ATP model with integer time. However, in industry practices, integer times are very rare and the model developed using integer times is therefore approximating the real system. Various alternative models for an ATP system with time lags have been developed and evaluated. In most cases, these models have assumed that the time lags are integer multiples of a unit time grid. However, integer time lags are very rare in practices, and therefore models developed using integer time lags only approximate real systems. The differences occurring by this approximation frequently result in significant accuracy degradations. To introduce the ATP model with time lags, we first introduce the dynamic production function. Hackman and Leachman's dynamic production function in initiated research directly related to the topic of this paper. They propose a modeling framework for a system with non-integer time lags and show how to apply the framework to a variety of systems including continues time series, manufacturing resource planning and critical path method. Their formulation requires no additional variables or constraints and is capable of representing real world systems more accurately. Previously, to cope with non-integer time lags, they usually model a concerned system either by rounding lags to the nearest integers or by subdividing the time grid to make the lags become integer multiples of the grid. But each approach has a critical weakness: the first approach underestimates, potentially leading to infeasibilities or overestimates lead times, potentially resulting in excessive work-inprocesses. The second approach drastically inflates the problem size. We consider an optimized ATP system with non-integer time lag in supply chain management. We focus on a worldwide headquarter, distribution centers, and manufacturing facilities are globally networked. We develop a mixed integer programming(MIP) model for ATP process, which has the definition of required data flow. The illustrative ATP module shows the proposed system is largely affected inSCM. The system we are concerned is composed of a multiple production facility with multiple products, multiple distribution centers and multiple customers. For the system, we consider an ATP scheduling and capacity allocationproblem. In this study, we proposed the model for the ATP system in SCM using the dynamic production function considering the non-integer time lags. The model is developed under the framework suitable for the non-integer lags and, therefore, is more accurate than the models we usually encounter. We developed intelligent ATP System for this model using genetic algorithm. We focus on a capacitated production planning and capacity allocation problem, develop a mixed integer programming model, and propose an efficient heuristic procedure using an evolutionary system to solve it efficiently. This method makes it possible for the population to reach the approximate solution easily. Moreover, we designed and utilized a representation scheme that allows the proposed models to represent real variables. The proposed regeneration procedures, which evaluate each infeasible chromosome, makes the solutions converge to the optimum quickly.

Numerical Simulation of Vertical Wall Fires I. Turbulent Natural Convection Along Vertical Wall (수직벽화재의 수치 시뮬레이션 I. 수직벽 난류자연대류)

  • Park, Woe-Chul;Trouve, Arnaud
    • Fire Science and Engineering
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    • v.22 no.3
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    • pp.181-187
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    • 2008
  • Numerical simulation of natural convection along a vertical wall was carried out to evaluate the computational fluid dynamics simulator, which is to be utilized for study of vertical wall fires. The computed velocity and temperature profiles were compared with measurements over the turbulent boundary layer formed along the wall of 4m high and constant temperature. It fumed out that the simulator with default parameters failed to predict the turbulent natural convection showing the boundary layer flow laminar. The grid size $\Delta$x=5mm, ${\Delta}y={\Delta}z=10mm$ and Smagorinsky constant of the large eddy simulation $C_s$=0.1 were chosen through parametric investigations. Though turbulent mixing was not enough, the velocity distribution near wall, peak velocity, and temperature profile in the turbulent boundary layer agreed well with the measurements.

A Study on Improving High-Power Induction Motor Starting (대용량 유도전동기 기동 개선에 관한 연구)

  • Son, Seok-Geum
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.9 no.2
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    • pp.178-184
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    • 2016
  • The motor power of the industry to use the electric energy is gradually increased. The electric motor generates a voltage drop in the starting current during startup. The starting current is started it is difficult to have an adverse effect on neighboring power systems with large motor starting when the voltage drop across the power grid. In addition to that the motor torque according to the load depending on the size of the rotation speed is changed to a motor start-up speed is important. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

Implementation of Small-Scale Wind Turbine Monitoring and Control System Based on Wireless Sensor Network (무선 센서 네트워크 기반 소규모 풍력발전기 모니터링 및 제어 시스템 구현)

  • Kim, Do-Young;Kim, Young-Chon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.9
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    • pp.1808-1818
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    • 2015
  • Recently, the wind power has experienced great attentions and growths among many renewable energy sources. To increase the power generation performance and economic feasibility, the size of wind turbine (WT) is getting bigger and most of wind power plants are being constructed on offshore. Therefore, the maintenance cost is relatively high because boats or helicopters are needed operators to reach the WT. In order to combat this kind of problem, remote monitoring and control system for the WT is needed. In this paper, the small-scale WT monitoring and control system is implemented using wireless sensor network technologies. To do this, sensor devices are installed to measure and send the WT status and control device is installed to receive control message for specific operation. The WT is managed by control center through graphic user interface (GUI) based monitoring and control software. Also, smart device based web-program is implemented to make the remote monitoring of the WT possible even though operators are not in control room.

Computer simulation of the effects of anisotropic grain boundary energy on grain growth in 2-D (이방성 결정립 계면에너지의 2차원 결정립 성장에 미치는 효과에 대한 컴퓨터 모사)

  • Kim, Shin-Woo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.4
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    • pp.178-182
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    • 2012
  • The grain growth is very important because of its great influence on the various materials properties. Therefore, in this study, the effects of anisotropic grain boundary energy on grain growth in 2-D have been investigated with a large scale phase field simulation model on PC. A $2000{\times}2000$ grid system and the initial number of grains of about 73,000 were used in the computer simulation. The anisotropic ratio of grain boundary energy, ${\sigma}_{max}/{\sigma}_{min}$, has been varied from 1 to 3. As the anisotropy increased, the grain growth exponent, n, increased from 2.05 to 2.37. The grain size distribution showed a central plateau in the isotropic case, and was changed into no central plateau and the increasing population of very small grains in the anisotropic case, resulting from slowly disappearing grains. Finally, simulated microstructures were compared according to anisotropy.

2-D Inundation Analysis According to Post-Spacing Density of DEMs from LiDAR Using GIS (GIS를 활용한 LiDAR 자료의 밀도에 따른 2차원 침수해석)

  • Ha, Chang-Yong;Han, Kun-Yeun;Cho, Wan-Hee
    • Journal of the Korean Association of Geographic Information Studies
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    • v.13 no.1
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    • pp.74-88
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    • 2010
  • In this study, the points of LiDAR were modified in order to generate various DEM resolutions by applying LiDAR data in Ulsan. Since the LiDAR data have points with 1m intervals, the number of points for each resolution was modified to the size of 1, 5, 10, 30, 50, 100m by uniformly eliminating the points. A runoff analysis was performed on Taehwa river and its tributary, Dongcheon, with 200 year rainfall exceedance probability. 2-dimensional inundation analysis was performed based on the density of LiDAR data using FLUMEN, which was used to establish domestic flood risk map. Once DEM data obtained from LiDAR survey are used, it is expected that the study results can be used as data in determining optimal grid spacing, which is economical, effective and accurate in establishing flood defence plans including the creation of flood risk map.

Large-Eddy Simulation of Turbulent Channel Flow using a Viscous Numerical Wave Tank Simulation Technique (점성 수치파랑수조 구축을 위한 LES 기술의 평판간 난류유동에의 적용)

  • Park, Jong-Chun;Kang, Dae-Hwan;Kim, Bang-Eun;Yoon, Hyeon-Sik;Chun, Ho-Hwan
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.204-212
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    • 2003
  • As the first step to investigate the nonlinear interactions between turbulence and marine structures inside a viscous NWT, a LES technique was applied to the turbulent channel flow for $Re_{T}=150$, in this paper. The employed models were 4 types, such as the Smagorinsky model, the Dynamic SGS model, the Structure Function model and the Generalized Normal Stress model. The simulated data in time-series for the LESs were averaged in both time and space and performed statistical analysis. And results of the LESs were compared with those of a DNS developed in the present study and two spectral methods by Yoon et al.(2003) & Kim et al.(1987). It seems to be quite difficult to evaluate their performances to the present problem, but is seen that the accuracy of LESs are still related to the number of grids(or fine grid size).

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Suitability Analysis of Onshore Wind Farm using GIS Program and Digital maps (GIS 및 수치지도를 활용한 육상풍력발전단지 적지분석)

  • Park, Jae-Hyeong;Lee, Hwa-Woon;Kim, Dong-Hyuk;Kim, Hyun-Goo;Kim, Tae-Wook
    • Journal of Environmental Science International
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    • v.23 no.11
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    • pp.1919-1927
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    • 2014
  • In order to decide the location of appropriate onshore wind farm with higher potential wind energy, several decision processes using Geographic Information System (GIS) including Digital Elevation Map (DEM) were proposed and we also estimated the wind resources through the proposed decision process. Decision process consists with three steps. First step is excluding inappropriate location geographically using DEM data including SRTM (Shuttle Radar Topography Mission) terrain data, landslide, land-use, roadway, and forest road data. And the second step of decision process is consideration of the difficulty caused by the natural environmental problem. This step is carried out using ECVAM (Environmental Conservation Value Assessment Map) data. And final step is determination of the most suitable location through the Moving Suitability Identification Method (MSIM) based on the moving potentially estimated wind resources area. Proposed decision process was applied over the Korean Peninsula. Wind resource potential estimated by the first and the second step is cases shows 35.09 GW and 7.17 GW, respectively, and the total evaluated energy from the all proposed step were 0.43 GW and 1.87 GW for the 3 km and 1.5 km geographical grid size, respectively.

Load Shedding Method based on Grid Hash to Improve Accuracy of Spatial Sliding Window Aggregate Queries (공간 슬라이딩 윈도우 집계질의의 정확도 향상을 위한 그리드 해쉬 기반의 부하제한 기법)

  • Baek, Sung-Ha;Lee, Dong-Wook;Kim, Gyoung-Bae;Chung, Weon-Il;Bae, Hae-Young
    • Journal of Korea Spatial Information System Society
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    • v.11 no.2
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    • pp.89-98
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    • 2009
  • As data stream is entered into system continuously and the memory space is limited, the data exceeding the memory size cannot be processed. In order to solve the problem, load shedding methods which drop a part of data to prevent exceeding the storage space have been researched. Generally, a traditional load shedding method uses random sampling with optimized rate according to data deviation. The method samples data not to distinguish those used in spatial query because the method uses only a random sampling with optimized rate according to data deviation. Therefore, the accuracy of query was reduced in u-GIS environment including spatial query. In this paper, we researched a new load shedding method improving accuracy of the query in u-GIS environment which runs spatial query and aspatial query simultaneously. The method uses a new sampling method that samples data having low probability used in query. Therefore proposed method improves spatial query accuracy and query processing speed as applying spatial filtering operation to sampling operator.

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An Algorithm for generating Cloaking Region Using Grids for Privacy Protection in Location-Based Services (위치기반 서비스에서 개인 정보 보호를 위한 그리드를 이용한 Cloaking 영역 생성 알고리즘)

  • Um, Jung-Ho;Kim, Ji-Hee;Chang, Jae-Woo
    • Journal of Korea Spatial Information System Society
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    • v.11 no.2
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    • pp.151-161
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    • 2009
  • In Location-Based Services (LBSs), users requesting a location-based query send their exact location to a database server and thus the location information of the users can be misused by adversaries. Therefore, a privacy protection method is required for using LBS in a safe way. In this paper, we propose a new cloaking region generation algorithm using grids for privacy protection in LBSs. The proposed algorithm creates a m inimum cloaking region by finding L buildings and then performs K-anonymity to search K users. For this, we make use of not only a grid-based index structure, but also an efficient pruning techniques. Finally, we show from a performance analysis that our cloaking region generation algorithm outperforms the existing algorithm in term of the size of cloaking region.

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