• Title/Summary/Keyword: local energy

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Flow Field Measurement of Natural Convection in a Rectangular Cavity Using Laser Speckle Photography (레이저 반점(斑點)을 이용한 사각형(四角形) 공동(空洞)내의 자연대류(自然對流) 유동장(流動場) 측정(測定))

  • Yang, Soong-Hyo;Chung, Woo-Nam;Park, Chan-Kuk;Kang, Yung-Kyu
    • Solar Energy
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    • v.9 no.2
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    • pp.51-57
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    • 1989
  • A two-dimensional velocity map of natural convection in a rectangular cavity is determined using laser speckle photography. Isovelocity contour drawn by spatial filtering and local velocity by pointwise method are obtained. These results are compared with those of numerical analysis.

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Theoretical Analysis on the Hot Surface Ignition of a Rectangular-Shape Solid Fuel

  • Kim, Se-Won
    • Journal of Energy Engineering
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    • v.4 no.2
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    • pp.297-302
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    • 1995
  • Ignition of a reactive solid in a shape of square corner by a hot surface is studied theoretically. Ignition time and the location of ignition point are determined as a function of dimensionless parameters, with the use of the homogeneous model of ignition. The effect of geometry on the ignition of solid fuel results in the local characteristics: the reaction is initiated in a hot point in depth of the substance. It is shown that ignition time is proportional to the dimensionless initial temperature, whereas for the ignition of the semiinfinite body this dependence was quadratic.

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Adaptive Data Association for Multi-Target Tracking using Relaxation

  • Lee, Yang-Weon;Hong Jeong
    • Journal of Electrical Engineering and information Science
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    • v.3 no.2
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    • pp.267-273
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    • 1998
  • This paper introduces an adaptive algorithm determining the measurement-track association problem in multi-target tracking(MTT). We model the target and measurement relationships with mean field theory and then define a MAP estimate for the optimal association. Based on this model, we introduce an energy function defined over the measurement space, that incorporates the natural constraints for target tracking. To find the minimizer of the energy function, we derived a new adaptive algorithm by introducing the Lagrange multipliers and local dual theory. Through the experiments, we show that this algorithm is stable and works well in general environments. Also the advantages of the new algorithm over other algorithms are discussed.

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Boundary element analysis of singular thermal stresses in a unidirectional laminate

  • Lee, Sang Soon;Kim, Beom Shig
    • Structural Engineering and Mechanics
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    • v.5 no.6
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    • pp.705-713
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    • 1997
  • The residual thermal stresses at the interface corner between the elastic fiber and the viscoelastic matrix of a two-dimensional unidirectional laminate due to cooling from cure temperature down to room temperature were studied. The matrix material was assumed to be thermorheologically simple. The time-domain boundary element method was employed to investigate the nature of stresses on the interface. Numerical results show that very large stress gradients are present at the interface corner and this stress singularity might lead to local yielding or fiber-matrix debonding.

Overviews on Energy Savings through Lubrication Improvements (윤활유 개선을 통한 에너지 절감 동향)

  • 이안성
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.107-114
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    • 2000
  • As one of the strategies to sustain the maximum output with the total minimum cost, huge plants worldwide, such as steel mills, refineries, petrochemical plants, and etc., may and will plan and implement the minimization of operating and maintenance costs for their own. This paper is to review the foreign cases of energy savings through lubrication improvements as one of the actions for that purpose and summarize their directions, and also to look at one such local test case.

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Sound Source Investigation of Outer Rotor BLDC Motor (외부회전자형 BLDC 전동기의 소음원 규명)

  • Lee, Chang-Min;Shin, Young-Hun;Moon, Jung-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.3
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    • pp.208-213
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    • 2012
  • With great advancement of the automobile functions, environmental factors become important performances, especially noise. This paper investigates noise sources of outer rotor type BLDC motor using in the air-conditioner of the automobiles. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. Structural analysis is conducted through modal test and analysis. For modal analysis, 3D finite element analysis is carried out using commercial program ansys. Electromagnetic causes are analyzed from local force that is computed by Maxwell stress tensor method. Local force excites structure of motor directly. Finally, correlation analysis is performed to determine effect between noise causes.

Local path-planning of a 8-dof redundant robot for the nozzle dam installation/detachment of the nuclear power plants

  • Park, Ki C.;Chang, Pyung H.;Kim, Seung H.
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10a
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    • pp.133-136
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    • 1996
  • The nozzle dam task is essentially needed to maintain and repair nuclear power plants. For this task, an 8-dof redundant robot is studied with a local path-planning method[l] which is effective to find the optimal joint path in the constrained environment. In this paper, the method[l] is improved practically with the weight matrix and efficient algorithm to find working set. The effectiveness of the proposed method is demonstrated by simulation and animation.

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Observation of local water content and current density in the PEMFC system (고분자 전해질 연료전지의 전류밀도와 국소 함수량 관찰)

  • Ko, Dong-Soo;Moon, Cheor-Ron;Choi, Gyung-Min;Kim, Duck-Jool;Jung, Ji-Hwan
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.05a
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    • pp.69-72
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    • 2008
  • The local water contents and water transfer characteristics in the PEMFC system were investigated by numerical simulations and experiments. The performance of a lab-scale PEMFC is measured for fully humidified gases conditions and non-humidified ones. In order to observe the local water contents and water transfer characteristics inside PEMFC, the numerical simulation using CFD module on STAR-CD(es-pemfc) were conducted. The results show that the water content was increased as increasing current density, whereas it was decreased in high current density region. Then there was close correlation between high water content and internal temperature inside of MEA, and high current density was observed when internal temperature was dramatically increased.

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