• Title/Summary/Keyword: Multiple Grid

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A Multiple-Item Scale for Measuring Food Service Quality - An Application of the Hierarchical Service Quality Approach - (외식 서비스 품질(FOODSERVQUAL) 측정을 위한 다문항 척도 - 위계적 서비스 품질 모형에의 적용 -)

  • Kim, Sang-Ho
    • Culinary science and hospitality research
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    • v.15 no.4
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    • pp.227-244
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    • 2009
  • This study was conducted to develop a multiple-item scale for measuring the food service quality in the restaurant industry. For developing the scale, Kelly Repertory Grid Methods were conducted. Collected data of food service quality were analyzed with the reliability analysis and the factor analysis of SPSS 12.0 and the 3rd-order confirmatory factor analysis of LISREL 8.70. The food service quality model of this study is conceptually based on the Brady and Cronin(2001)'s hierarchical approach to the service quality model. The hierarchical model of the food service quality which comprises three constructs of the physical environment quality, the interaction quality and the food quality as a primary dimension. The hierarchical approaches to the food service quality help overcome the limitations of the SERVQUAL model for which some arguments have been made that it lacks a clear division between the dimensions and its subsequent overlapping between them.

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Two-Way Hybrid Power-Line and Wireless Amplify-and-Forward Relay Communication Systems

  • Asiedu, Derek Kwaku Pobi;Ahiadormey, Roger Kwao;Shin, Suho;Lee, Kyoung-Jae
    • Journal of Advanced Information Technology and Convergence
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    • v.9 no.1
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    • pp.25-37
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    • 2019
  • Power-line communication (PLC) has influenced smart grid development. In addition, PLC has also been instrumental in current research on internet-of-things (IoT). Due to the implementation of PLC in smart grid and IoT environments, strides have been made in PLC and its combination with the wireless system to form a hybrid communication system. Also, PLC has evolved from a single-input-single-output (SISO) configuration to multiple-input-multiple-output (MIMO) configuration system, and from a point-to-point communication system to cooperative communication systems. In this work, we extend a MIMO wireless two-way amplify-and-forward (AF) cooperative communication system to a hybrid PLC and wireless (PLC/W) system configuration. We then maximize the weighted sum-rate for the hybrid PLC/W by optimizing the precoders at each node within the hybrid PLC/W system. The sum-rate problem was found to be non-convex, therefore, an iterative algorithm is used to find the optimal precoders that locally maximize the system sum-rate. For our simulation results, we compare our proposed hybrid PLC/W configuration to a PLC only and wireless only configuration at each node. Due to an improvement in system diversity, the hybrid PLC/W configuration outperformed the PLC only and wireless only system configurations in all simulation results presented in this paper.

Cross-layer Design of Joint Routing and Scheduling for Maximizing Network Capacity of IEEE 802.11s based Multi-Channel SmartGrid NAN Networks (IEEE 802.11s 를 사용한 스마트그리드 NAN 네트워크의 최대 전송 성능을 위한 다중 채널 스케쥴링과 라우팅의 결합 설계)

  • Min, Seok Hong;Kim, Bong Gyu;Lee, Jae Yong;Kim, Byung Chul
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.25-36
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    • 2016
  • The goal of the SmartGrid is to maximize energy efficiency by exchanging bi-directional real-time power information with the help of ICT(Information and Communication Technology). In this paper, we propose a "JRS-MS" (Joint Routing and Scheduling for Multi-channel SmartGrid) algorithm that uses numerical modeling methods in IEEE 802.11s based STDMA multi-channel SmartGrid NAN networks. The proposed algorithm controls the amount of data transmission adaptively at the link layer and finds a high data-rate path which has the least interference between traffic flows in multi-channel SmartGrid NAN networks. The proposed algorithm improve transmission performance by enhancing network utilization. By comparing the results of performance analysis between the proposed algorithm and the JRS-SG algorithm in the previous paper, we showed that the JRS-MS algorithm can improve transmission performance by maximally utilizing given network resources when the number of flows are increasing in the multi-hop NAN wireless mesh networks.

Selection Method of Multiple Threshold Based on Probability Distribution function Using Fuzzy Clustering (퍼지 클러스터링을 이용한 확률분포함수 기반의 다중문턱값 선정법)

  • Kim, Gyung-Bum;Chung, Sung-Chong
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.5 s.98
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    • pp.48-57
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    • 1999
  • Applications of thresholding technique are based on the assumption that object and background pixels in a digital image can be distinguished by their gray level values. For the segmentation of more complex images, it is necessary to resort to multiple threshold selection techniques. This paper describes a new method for multiple threshold selection of gray level images which are not clearly distinguishable from the background. The proposed method consists of three main stages. In the first stage, a probability distribution function for a gray level histogram of an image is derived. Cluster points are defined according to the probability distribution function. In the second stage, fuzzy partition matrix of the probability distribution function is generated through the fuzzy clustering process. Finally, elements of the fuzzy partition matrix are classified as clusters according to gray level values by using max-membership method. Boundary values of classified clusters are selected as multiple threshold. In order to verify the performance of the developed algorithm, automatic inspection process of ball grid array is presented.

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Development of a 100kW charging infra for electrical bus (전기버스용 100kW급 충전인프라 개발)

  • Lee, Chung-Woo;Oh, Seung-Hun;Lee, Yun-Jae;Choi, Eun-Sik;Kang, Byung-Kwan;Ryu, Kang-Yeul;Kim, Hee-Jung
    • Proceedings of the KIPE Conference
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    • 2013.11a
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    • pp.117-118
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    • 2013
  • Recent global warming to the promotion of electric vehicles (EV), plug-in hybrid (PEV), including the next generation of cars and solar power, wind power and other renewable energy, and next-generation power grid (smart grid) are getting attention. In addition, the system utilizes the battery life in the industry and the convenience of a variety of social systems, economics, environmental impact, and the inherent potential to change significantly, and you can not walk into a next-generation industrial strategy and the need increases more and more present, and its early commercialization In order to do this, as well as a key energy source, the battery charger for charging efficiency technologies is essential. In this paper, fast charge multiple battery modules and optional modules that can charge distribution charge will be introduced.

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Simulink-based Modelling and Simulation for a Single-phase UPFC (Simulink를 이용한 단상 UPFC 모델링 및 시뮬레이션)

  • Kang, Moon-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.3
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    • pp.523-530
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    • 2009
  • This paper presents a study on a small scale single-phase UPFC preliminary researches on power quality compensating schemes of electrical railway. As the UPFC is very complicated power-electronic system consisting of grid-connected transformers, four single phase inverters interconnected with dc-link capacitors and various electrical apparatuses, multiple controllers and control algorithms are needed, and entire UPFC has been modelled in the form of block diagrams and simulated by using Simulink. The main purpose of the compensating system is to manage reactive and active powers with the four single phase inverters, so, the control effort has been focused on the power flow control and has been realized through the hysteresis current control of the single phase inverters. And transport-delayed PLL with additional delay-time compensating term has been used to synchronize a grid voltage and the simulation results have shown that the compensating term could improve PLL performance under some frequency variation of the voltage.

A Novel Algorithm for Reducing Restoration Time in Smart Distribution Systems Utilizing Reclosing Dead Time

  • Hussain, Akhtar;Choi, Myeon-Song;Lee, Seung-Jae
    • Journal of Electrical Engineering and Technology
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    • v.9 no.6
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    • pp.1805-1811
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    • 2014
  • After an occurrence of a fault in any distribution system, it is desired to limit the effects of the fault to smallest possible area and restore the un-faulty areas as soon as possible. Due the advancements in communication technologies, this task can be achieved in multiple efficient ways. In order to decrease the restoration time in the Smart Grid Distribution Management System (SDMS) a communication based algorithm is proposed in this paper, in which the restoration can be done during reclosing. This paper also analyzes various communication failures with power failures cases including the entire network of communication failures. Results of all these cases have been verified by doing simulations.

Sonar-Based Certainty Grids for Autonomous Mobile Robots (초음파 센서을 이용한 자율 이동 로봇의 써튼티 그리드 형성)

  • 임종환;조동우
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.39 no.4
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    • pp.386-392
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    • 1990
  • This paper discribes a sonar-based certainty grid, the probabilistic representation of the uncertain and incomplete sensor knowledge, for autonomous mobile robot navigation. We use sonar sensor range data to build a map of the robot's surroundings. This range data provides information about the location of the objects which may exist in front of the sensor. From this information, we can compute the probability of being occupied and that of being empty for each cell. In this paper, a new method using Bayesian formula is introduced, which enables us to overcome some difficulties of the Ad-Hoc formula that has been the only way of updating the grids. This new formula can be applied to other kinds of sensors as well as sonar sensor. The validity of this formula in the real world is verified through simulation and experiment. This paper also shows that a wide angle sensor such as sonar sensor can be used effectively to identify the empty area, and the simultaneous use of multiple sensors and fusion in a certainty grid can improve the quality of the map.

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A Study on the Flow Characteristics Around an Axial Fan of Rotary Burner (로터리 버너의 축류형 팬 주위 유동특성 연구)

  • Ko, D.G.;Cho, D.J.;Yoon, S.J.
    • Journal of ILASS-Korea
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    • v.8 no.1
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    • pp.1-8
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    • 2003
  • The flow analysis of the axial fan of rotary burner was performed by SIMPLE(Semi Implicit Method for Pressure Linked Equations) algorithm and finite volume mothod performed in the case of 3-D, incompressible, turbulent flow. In this study, the coordinate transformation was adapted for the complex geometry of axial fan, and the standard $k-{\varepsilon}$ model and wall function method were used for analysis of turbulent flow. Multi-block grid system was used for flow field and divided into four domains such as the inlet, outlet, flow field of rotating vane, and tip clearance. Fan rotation was simulated by rotational motion using MRF(Multiple Rotating Reference Frame) in steady, incompressible state flow.

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Development of Live Load Moment Equations Using Orthotropic Plate Theory (직교 이방성 판 이론을 이용한 바닥판 활하중 모멘트 산정식 개발)

  • Ahn Ye-Jun;Nam Suk-Hyun;Park Jang-Ho;Shin Yung-Seok
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.749-756
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    • 2006
  • Because of the orthotropic elastic properties and significant two-way bending action, orthotropic plate theory may be suitable for describing the behavior of concrete filled grid bridge decks. Current AASHTO LRFD Bridge Design Specification(2004) has live load moment equations considering flexural rigidity ratio between longitudinal and transverse direction, but the Korea highway bridge design specification(2005) doesn't. The Korea highway bridge standard specification LRFD(1996) considers an orthotropic plate model with a single load to estimate live load moments in concrete filled grid bridge decks, which may not be conservative. This paper presents live load moment equations for truck and passenger car, based on orthotropic plate theory. The equations of truck model use multiple presence factor, impact factor, design truck and design tandem of the Korea highway bridge standard specification LRFD(1996). The estimated moments are verified through finite-element analyses.

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