• 한국해양공학회지
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• 제15권1호
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• pp.45-51
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• 2001

In order to clarify the seasonal variation of the residual current and the material transportation process in Hiroshima Bay, JAPAN, the real-time simulation of residual current and particle tracking by using the Euler-Lagrange model were carried out. The calculated tidal current, water temperature, and salinity showed good agreement with the observed ones. The residual currents showed a southward flow pattern at the upper layer, and a northward flow pattern at the lower layer. The flow structure of the residual current in Hiroshima Bay is an estuarine circulation affected by density flow and wind driven current. The residual current plays an important role of material transportation in the bay.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.471-474
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• 2006

The Mixer is apparatus that help precipitation or an inhomogeneous distribution of various phases to be mixed and that user makes necessary material mixing one or the other. Mainly the mixer which is used from chemical and food industry is very important system in engineering that mixes the material. The inside flow of the mixer under the actual states which put a basis in flow of the fluid is formed rotation of the impeller. The inside flow of impeller will be caused by various reasons change with shape of impeller, number of rotation, mixing material and flow pattern of free surface etc. Also mixer study depended in single-phase flow and experimental research. So the numerical analysis of flow mixing solid-fluid particle is simulated. It is become known, that the case where agitator inside working fluid includes the solid particle the sinkage reverse which the solid particle has decreases an agitation efficiency. From the research which it sees the hazard solid which examines the effect where the change of the sinkage territory which it follows agitation number of revolution and diameter of the particle goes mad to an agitator inside flow distribution - numerical analysis the inside flow distribution of liquid state with Eulerian Two-Phase Method.

• 한국정밀공학회지
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• 제30권9호
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• pp.943-950
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• 2013

This paper describes the thermal contact resistance and its effect on the performance of thermal interface material. An ASTM D 5470 based apparatus is used to measure the thermal interface resistance. Bulk thermal conductivity of different interface material is measured and compared with manufacturers' data. Also, the effect of grease void in the contact surface is investigated using the same apparatus. The flat type thermal interface tester is proposed and compared with conventional one to consider the effect of lateral heat flow. The results show that bulk thermal conductivity alone is not the basis to select the interface material because high bulk thermal conductivity interface material can have high thermal contact resistance, and that the center voiding affects the thermal interface resistance seriously. On the aspect of heat flow direction, thermal impedance of the lateral heat flow shows higher than that of the longitudinal heat flow by sixteen percent.

• 한국해양공학회지
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• 제10권3호
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• pp.117-124
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• 1996

A fluidized bed combustion chamber is widely used to incinerate waste material. The most important factor designing the incinerator is the flow characteristics in a fluidized bed, because combustion efficiency is influenced by the flow characteristics. This paper has invesitigated the flow characteristics of bubbles in fluidized bed by means of meassuring a pressure fluctuation in the fluidized bed. A pressure probe system has used to measure the pressure. The data concerned with bubble rising velocity, bubble size, distribution of bubbles and frequency of bubble generation or decay are obtained to find the flow characteristics of bubbles in the fluidized bed. The result obtained from this experimental study can be used to design the fuel feeding system of fluidized bed combustion type incinerator. And it is possible to predict the mixing of waste material and fluidizing material.

• 융합보안논문지
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• 제13권1호
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• pp.25-30
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• 2013

본 논문에서는 국내 물류산업의 경쟁력을 높이고 물류 선진화를 도모하기 위한 성과지표를 분석하고 세부적인 IT서비스를 제시한다. 여기서 물류 기업의 성과는 크게 효율성, 지속가능성 및 경제성 측면으로 구분하여 평가지표를 설정하고 IT서비스는 기업 및 공공물류로 분류하여 기업들에게 필요한 IT서비스를 분석한다. 아울러 사례연구로서 평택항 관련 종사자 즉, 물류기업 및 무역업, 공무원, 지역주민 등을 대상으로 실시한 설문조사 결과(SPSS 분석)를 통하여 물류기업의 현황을 진단하고 우선적으로 요구되는 물류 IT서비스의 우선순위를 조사한다. 분석결과, 물류산업의 생산성과 효율성을 높이기 위하여 전문인력의 확보와 표준화가 요구되고 시급한 IT서비스로서 물류자동화 기계화, u-Port 구축, 녹색친환경물류 그리고 물류보안 기술의 구현이 필요함을 알 수 있다.

• 한국가시화정보학회지
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• 제21권3호
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• pp.75-84
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• 2023

In this study, we conducted analysis of bubble dynamics and flow of liquid phase change material(PCM) using shadowgraphy and particle image velocimetry(PIV). Characteristics of internal flow varied depending on locations of injection when solid PCM was liquefied from heated vertical wall. When bubbles rose immediately, they exhibited elliptical shape and zigzag trajectory. In contrast, when bubbles rose after merging at the bottom of solid PCM, with equivalent diameter for the inter-wall distance of 0.64 or greater, they showed a jellyfish shape and strong rocking behavior. It was observed by the PIV that the small ellipse bubbles made most strong flow inside the liquid PCM. Furthermore, the flow velocity was highest in the case of front injection, as the directions of temperature gradients and bubble-driven flow were aligned. The results underscore the significant influence of injection location on various characteristics, including bubble size, shape, rising path of bubbles, and internal flow.

• 자원리싸이클링
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• 제30권3호
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• pp.63-69
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• 2021

폐기물에서의 납 회수 및 재활용을 통해 원료공급 안정화와 환경오염 예방을 동시에 도모할 수 있고 실제로도 최근 폐납축전지 위주의 재활용을 통해 납 원자재 공급 측면에서 긍정적인 효과를 보고 있다. 다만 향후 납 회수 및 재활용의 효과를 극대화하기 위해서 납의 물질 흐름의 현황을 효과적으로 파악할 필요가 있는데, 배출원 등의 복잡성과 다양성으로 인해 관련 조사가 번거로울 수 있다. 이 경우 편의상 인터넷 공개자료를 통한 예비 조사의 선수행이 효과적일 수 있다. 따라서, 본 연구에서는 공공기관 공개자료를 통해 국내 납의 흐름을 파악하여 향후 납 회수/재활용에 효율성을 기여하고자 한다. 이에 본 연구에서는 UN Comtrade와 국내 화학물질배출×이동량 사이트 자료를 이용하여 납의 수입량 및 배출×이동량을 파악하고 이를 국가통합자원관리시스템에서 제시된 납의 흐름과 비교하였다. 그 결과 폐납축전지 등 주요 항목별 관련 납의 흐름이 각 사이트 간에 대략적인 일치를 보였다.

• 한국항공운항학회지
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• 제16권4호
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• pp.26-34
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• 2008

This article provides a comprehensive treatment of cracks in non-homogeneous structural materials such as functionally graded materials (FGMs). It is assumed that the material properties depend only on the coordinate perpendicular to the crack surfaces and vary continuously along the crack faces. By using laminated composite plate model to simulate the material non-homogeneity, we present an algorithm for solving the system based on Laplace transform and Fourier transform techniques. Unlike earlier studies that considered certain assumed property distributions and a single crack problem, the current investigation studies multiple crack problem in the FGMs with arbitrarily varying material properties. As a numerical illustration, transient thermal flow intensity factors for a metal-ceramic joint specimen with a functionally graded interlayer subjected to sudden heating on its boundary are presented. The results obtained demonstrate that the present model is an efficient tool in the fracture analysis of non-homogeneous material with properties varying in the thickness direction.

• 산업공학
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• 제16권spc호
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• pp.93-98
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• 2003

This paper addresses an AGV dispatching problem in semiconductor clean-room bays where AGVs move cassettes of wafers between machines or machines and a central buffer. Since each machine in a bay has a local buffer of limited capacity, material flow should be controlled in a careful way to maintain high system performance. It is regarded that two most important performance measures in a semiconductor bay are throughput rate and lead-time. The throughput rate is determined by a bottleneck resource and the lead-time depends on smooth material flow in the system. This paper presents an AGV dispatching procedure based on the concept of theory of constraints (TOC), by which dispatching decisions are made to utilize the bottleneck resource at the maximum level and to smooth the flow of material. The new dispatching procedure is compared with existing dispatching rules through simulation experiments.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.91-94
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• 2004

Preform design techniques have been investigated in efforts to reduce die wear and forming load and to improve material flow, filing ratio, etc. In hot forging processes, a thin deformed part of a workpiece, known as a flash, is formed in the narrow gap between the upper and lower tools. Although designers make tools that generate a flash intentionally in order to improve flow properties, excessive flash increases die wear and forming load. Therefore, it is necessary to make a preform shape that can reduce the excessive flash without changing flow properties. In this paper, a new preform design technique is proposed to reduce the excessive flash in a metal forging process. After a finite element simulation of the process is carried out with an initial billet, the flow of material in the flash region is traced from the final shape to the initial billet. The region belonging to the flash is then easily found in the initial billet. The finite element simulation is then carried out again with the modified billet from which the selected region has been removed. In several iterations of this technique, the optimal preform shape that minimizes the amount of flash without changing the forgeability can be obtained.