• Title/Summary/Keyword: Heterogeneous Distribution

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Basic Study on the Spatial Structure Analysis of the Evaporative Diesel Spray (증발디젤분무의 공간적 구조해석에 관한 기초 연구)

  • Yeom, J.K.
    • Journal of Power System Engineering
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    • v.14 no.3
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    • pp.5-12
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    • 2010
  • The purpose of this study is to analyze heterogeneous distribution of branch-like structure at downstream region of inner spray. The previous many studies about diesel spray structure have yet stayed in the analysis of 2-D structure, and there are very few of informations which are concerned with 3-D analysis of the structure. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray, and also the combustion characteristics of the diesel engines. Therefore, in order to investigate 3-D structure of evaporative spray the laser beam of 2-D plane was used in this study. Liquid fuel was injected from a single-hole nozzle (l/d=5) into a constant-volume vessel under high pressure and temperature in order to visualize the spray phenomena. The incident laser beam was offset on the central axis. From the images analysis taken by offset of laser beam, we examine formation mechanism of heterogeneous distribution by vortex flow at the downstream of the diesel spray. As the experimental results, the branch-like structure formed heterogeneous distribution of the droplets consists of high concentration of vapor phase in the periphery of droplets and spray tip of branch-like structure. Also the 3-D spatial structure of the evaporative diesel spray can be verified by images obtained from 2-D measurement methods.

Lifetime Distribution Model for a k-out-of-n System with Heterogeneous Components via a Structured Markov Chain (구조화 마코프체인을 이용한 이종 구성품을 갖는 k-out-of-n 시스템의 수명분포 모형)

  • Kim, Heungseob
    • Journal of Applied Reliability
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    • v.17 no.4
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    • pp.332-342
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    • 2017
  • Purpose: In this study, the lifetime distribution of a k-out-of-n system with heterogeneous components is suggested as Markov model, and the time-to-failure (TTF) distribution of each component is considered as phase-type distribution (PHD). Furthermore, based on the model, a redundancy allocation problem with a mix of components (RAPMC) is proposed. Methods: The lifetime distribution model for the system is formulated by the structured Markov chain. From the model, the various information on the system lifetime can be ascertained by the matrix-analytic (or-geometric) method. Conclusion: By the generalization of TTF distribution (PHD) and the consideration of heterogeneous components, the lifetime distribution model can delineate many real systems and be exploited for developing system operation policies such as preventive maintenance, warranty. Moreover, the effectiveness of the proposed RAPMC is verified by numerical experiments. That is, under the equivalent design conditions, it presented a system with higher reliability than RAP without component mixing (RAPCM).

Adsorption isotherm on the heterogeneous surface with spatially uneven periodic adsorption heat distribution (요철형 공간주기성을 갖는 Heterogeneous 표면 흡착열분포에 대한 흡착등온식)

  • 김철호;황보승
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.12 no.3
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    • pp.115-119
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    • 2002
  • An adsorption isotherm on the heterogeneous surface which has spatially periodic adsorption heat distribution was formalized. Usefulness of the formalized adsorption isotherm is discussed with the help of a model calculation. Statistical thermodynamics is used throughout.

Energy and Performance-Efficient Dynamic Load Distribution for Mobile Heterogeneous Storage Devices (에너지 및 성능 효율적인 이종 모바일 저장 장치용 동적 부하 분산)

  • Kim, Young-Jin;Kim, Ji-Hong
    • Journal of the Korea Society of Computer and Information
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    • v.14 no.4
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    • pp.9-17
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    • 2009
  • In this paper, we propose a dynamic load distribution technique at the operating system level in mobile storage systems with a heterogeneous storage pair of a small form-factor and disk and a flash memory, which aims at saving energy consumption as well as enhancing I/O performance. Our proposed technique takes a combinatory approach of file placement and buffer cache management techniques to find how the load can be distributed in an energy and performance-aware way for a heterogeneous mobile storage air of a hard disk and a flash memory. We demonstrate that the proposed technique provides better experimental results with heterogeneous mobile storage devices compared with the existing techniques through extensive simulations.

Model and Heuristics for the Heterogeneous Fixed Fleet Vehicle Routing Problem with Pick-Up and Delivery

  • Zhai, Shuai;Mao, Chao
    • Journal of Distribution Science
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    • v.10 no.12
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    • pp.19-24
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    • 2012
  • Purpose - This paper discusses the heterogeneous fixed fleet vehicle routing problem with pick-up and delivery (HFFVRPPD), for vehicles with different capacities, fixed costs, and travel costs. Research Design, data, methodology - This paper made nine assumptions for establishing a mathematical model to describe HFFVRPPD. It established a practical mathematical model, and because of the non-deterministic polynomial-time hard (NP-hard), improved the traditional simulated annealing algorithm and tested a new algorithm using a certain scale model. Result - We calculated the minimum cost of the heterogeneous fixed fleet vehicle routing problem (HFFVRP) with a single task and, on comparing the results with the actual HFFVRP for the single task alone, observed that the total cost of HFFVRPPD reduced significantly by 46.7%. The results showed that the new algorithm provides better solutions and stability. Conclusions - This paper, by comparing the HFFVRP and HFFVRPPD results, highlights certain advantages of using HFFVRPPD in physical distribution enterprises, such as saving distribution vehicles, reducing logistics cost, and raising economic benefits.

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Walsh Analysis of the State of Mixture in Heterogeneous Media and its Application (비균질체의 혼합상태에 대한 Walsh해석과 응용)

  • 박진무
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.1
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    • pp.164-169
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    • 1986
  • Walsh analysis is applied to the numerical specification of the volume distribution which is the key parameter in the formulation of the constitutive equations of heterogeneous media, indicating the geometrical state of the mixture. An example of two-dimensional volume distribution, its approximation, and the Walsh correlation coefficients are presented and the change of the information distribution in the operations is investigated. The phenomena of information concentration upon the large-scale Walsh coefficients are applied to the volumetric response of porous slids, clarifying the validity of the spherical-model calculation.

A study on the microstructure and micro-hardenss distribution in laser welded AZ31 magnesium alloy (AZ31 마그네슘합금 레이저 용접부의 미세조직 및 미소경도의 분포에 관한 연구)

  • Choi, Y.H.;Lee, M.Y.;Choi, S.H.
    • Laser Solutions
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    • v.15 no.3
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    • pp.11-15
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    • 2012
  • The laser weld of AZ31 magnesium alloy was characterized with OM, EBSD and micros vickers hardness tester in experiment. EBSD analysis and micro-hardness measurements were carried out at the three regions (Equiaxed Zone, Columnar Dendrite Zone, Base Metal) of the welded AZ31Mg alloy sheets. The magnesium alloy show the rectangular shape bead in laser weld. EBSD analysis revealed that the three regions show the heterogeneous distribution of grain size and microtexture. Micro-hardness measurement also revealed that the heterogeneous distribution of microstructure contributed to the heterogeneous micro-hardness distribution in the three regions.

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A Study on the Mixture Formation Process of Evaporating Diesel Spray by Offset Incidence Laser Beam

  • Yeom, Jeong-Kuk;Kang, Byung-Mu;Lee, Myung-Jun;Chung, Sung-Sik;Ha, Jong-Yul;Hajime Fujimoto
    • Journal of Mechanical Science and Technology
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    • v.16 no.12
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    • pp.1702-1709
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    • 2002
  • This paper analyzes heterogeneous distribution of branch-like structure at the downstream region of the spray. The liquid and vapor phase of the spray are obtained using a 35㎜ still camera and CCD camera in order to investigate spray structure of evaporating diesel spray. There have been many studies conducted on diesel spray structure but have yet only focused on the analyses of 2-D structure. There are a few information which is concerned with 3-D structure analysis of evaporating spray. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray and the combustion characteristics of the diesel engines. In this study, the laser beam of 2-D plane was used in order to investigate 3-D structure of evaporating spray The incident laser beam was offset on the central axis of the spray. From the analysis of images taken by offset laser beam, we will examine the formation mechanism of heterogeneous distribution of the diesel spray by vortex flow at the downstream of the spray. The images of liquid and vapor phase of free spray are simultaneously taken through an exciplex fluorescence method. Through this, the branch-like structure consisting of heterogeneous distribution of the droplets forms high concentrated vapor phase at the periphery of droplets and at the spray tip.

The Study on Residual Stress of Laser Weldment for the Heterogeneous Materials (이종재료의 레이저용접에서 잔류응력 평가)

  • 오세헌;민택기
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.3
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    • pp.119-125
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    • 2004
  • Generally, it is used the compensation spring to compensate the inaccuracy of screen image induced by thermal deformation in CRT monitor. Its mechanism is bi-metallic system made of heterogeneous metals and these is bonded by laser welding. But laser welding induces the non-uniform temperature distribution and locally residual stress is yielded by these temperature deviation. This paper studies residual stress of laser weldment using FEA and hole drilling method. The results are followed. In the case of heterogeneous materials weldment, higher residual stress induced in the weldment region of SUS 304 which have larger CTE than Ni 36 and residual stress on the middle of specimen is higher by 10.9% than that of its surface Measured residual stress of SUS 304 yield 481MPa and that of Ni 36 is 140.5MPa in the vicinity of the welding region. And the residual distribution is very similar in comparison with FEA result.

Gaussian Approximation of Stochastic Lanchester Model for Heterogeneous Forces (혼합 군에 대한 확률적 란체스터 모형의 정규근사)

  • Park, Donghyun;Kim, Donghyun;Moon, Hyungil;Shin, Hayong
    • Journal of Korean Institute of Industrial Engineers
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    • v.42 no.2
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    • pp.86-95
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    • 2016
  • We propose a new approach to the stochastic version of Lanchester model. Commonly used approach to stochastic Lanchester model is through the Markov-chain method. The Markov-chain approach, however, is not appropriate to high dimensional heterogeneous force case because of large computational cost. In this paper, we propose an approximation method of stochastic Lanchester model. By matching the first and the second moments, the distribution of each unit strength can be approximated with multivariate normal distribution. We evaluate an approximation of discrete Markov-chain model by measuring Kullback-Leibler divergence. We confirmed high accuracy of approximation method, and also the accuracy and low computational cost are maintained under high dimensional heterogeneous force case.