• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.4
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• pp.541-550
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• 1997

Computational and experimental investigations on the three-dimensional flowfield through an automotive cooling fan are carried out in this work. Steady, incompressible, three-dimensional, turbulent flow through a rotating axial-flow fan is analyzed with Reynolds averaged Navier-Stokes equations and standard k-.epsilon. turbulence model. The governing equations are discretized with finite-volume approximations in non-orthogonal curvilinear coordinates. Computational static pressures on the casing wall agree well with the experimental data which are measured in this work. And, they are sensitive to the change of tip clearance. The flowfield is not significantly affected by the thickness of the blade. The k-.omega. model gives the static pressure rise on the casing wall which is similar to that with the k-.epsilon. model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.138-144
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• 1996

In square die extrusion, flow guide and ide land play important roles for controlling the metal flow in die design. In the present work, the flow guide and the die land are considered for the die construction. Based on ALE description , rigid-viscoplastic finite element analysid is carried out to assess the effects of process and die design parameters. The thermal state affects greatly the product quality in hot extrusion. in the present work, the temperature distribution is also analyzed in theframwork of rigid-viscoplastic finite element computation. As a computational example, hot square die extrusion with flow guide and die land has been analyzed for the profile of a H section.

• Transactions of Materials Processing
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• v.22 no.8
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• pp.450-455
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• 2013

In the current study, a new dynamic recrystallization model for predicting high temperature flow stress is developed based on a physical model and the mean field theory. In the model, the grain aggregate is assumed as a representative volume element to describe dynamic recrystallization. The flow stress and microstructure during dynamic recrystallization were calculated using three sub-models for work hardening, for nucleation and for growth. In the case of work hardening, a single parameter dislocation density model was used to calculate change of dislocation density and stress in the grains. For modeling nucleation, the nucleation criterion developed was based on the grain boundary bulge mechanism and a constant nucleation rate was assumed. Conventional rate theory was used for describing growth. The flow stress behavior of pure copper was investigated using the model and compared with experimental findings. Simulated results by cellular automata were used for validating the model.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.196-208
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• 2017

This study presents an experimental work in a petrochemical company for scanning a buried pipeline using $Tc^{99m}$ radiotracer based on the measured velocity changes, in order to determine the flow reduction along a pipeline. In this work, $Tc^{99m}$ radiotracer was injected into the pipeline and monitored by sodium iodide scintillation detectors located at several positions along the pipeline. The flow velocity has been calculated between every two consecutive detectors along the pipeline. Practically, six experiments have been carried out using two different data acquisition systems, each of them being connected to four detectors. During the fifth experiment, a bypass was discovered between the scanned pipeline and another buried parallel pipeline connected after the injection point. The results indicate that the bypass had a bad effect on the volumetric flow rate in the scanned pipeline.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1475-1482
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• 2006

Wet compression means the injection of water droplets into the compressor of gas turbines. This method decreases the compression work and increases the turbine output by decreasing the compressor exit temperature through the evaporation of water droplets inside the compressor. Researches on wet compression, up to now, have been focused on the thermodynamic analysis of wet compression where the decrease in exit flow temperature and compression work is demonstrated. This paper provides thermodynamic and aerodynamic analysis on wet compression in a centrifugal compressor for a microturbine. The meanline dry compression performance analysis of centrifugal compressor is coupled with the thermodynamic equation of wet compression to get the meanline performance of wet compression. The most influencing parameter in the analysis is the evaporative rate of water droplets. It is found that the impeller exit flow temperature and compression work decreases as the evaporative rate increases. And the exit flow angle decreases as the evaporative rate increases.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.170-171
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• 2015

Resource procurement and material handling are considered as a significant part of construction project especially in large or tall building construction site. There are multiple variables that must be considered in a construction site during finishing work such as movement of materials, equipments, and workers. Therefore, it is difficult for construction workers to find the material handling path solely by intuition. The aim of this study is to propose a real-time path finding model suitable for complicated logistics flow in the field. The model explores the optimal transport path of finishing material with its basis on optimization algorithm, and it determines the direction of the Smart Sign. The proposed model is expected to be utilized for planning of efficient finishing material handling.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.575-578
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• 2002

원자력 중장기 연구개발 일환으로 수행중인 액체금속로 설계기술개발 프로젝트는 개념 설계분야와 기반기술구축 분야로 구성되어 있는 상호 긴밀한 연계가 강조되기 프로젝트이다. 대과제를 중심으로 각 세부과제 및 분야 내에서 시스템별 인터페이스 등이 종합적으로 관리되어야 할 필요성이 있는 프로젝트이다. 액체금속로 설계기술개발 프로젝트의 연구생산성 향상을 위해 공정계획을 수립하고, 프로젝트 수행 중에 산출되는 연구결과물을 검증하여, 검증된 자료를 프로젝트 수행원들에게 공유할 수 있게 Web WorkFlow를 이용한 자료 검증/공유시스템을 개발하여 운영하고 있으며, 최종적으로 검증된 자료는 데이터베이스를 구축하여 활용하고 있다. 이렇게 함으로써 한국원자력연구소에서 개발증인 액체금속로 설계 기술개발 프로젝트를 최적화된 계획 및 관리를 통하여 연구개발을 수행할 수 있을 것으로 예상된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.842-845
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• 2000

컴포넌트라는 소프트웨어 개발 기술에 대해서 중요성이 점점 높아만 가고 있는 가운데, 이 컴포넌트 기술를 이용하여 효율적이고, 실용적으로 소프트웨어를 개발 할 수 있도록 컴포넌트 기반의 소프트웨어 개발 방법에 대하여 연구 제시한다. 즉, 컴포넌트가 가지고 있는 구성요소로서 인터페이스라는 것이 있는데 이 인터페이스와 컴포넌트를 이용해서 만들고자 하는 시스템에 대한 요구사항에 맞게 분석 및 설계를 하고, 만들고자 하는 시스템과 컴포넌트의 투명성을 보여 줄 수 있는 방법에 대해서 Work Flow Model과 각각의 프로세스에 의해서 만들어지는 산출물을 통해서 컴포넌트 기반의 소프트웨어 개발 프로세스에 대해서 제시를 한다.

• Korean Journal of Construction Engineering and Management
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• v.2 no.4 s.8
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• pp.48-61
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• 2001

This study aims at improving work reliability. It proposes a way to overcome the limitations of current scheduling methods by providing a new framework, CPAM(Construction Process Analysis Model) based on the lean principles. It suggests methods which improve work reliability and production effectiveness with variability control methods. Also it suggests methods which reduce inventories of materials and equipment and WIP(Work In Process) using two techniques; Lookahead Schedule and Weekly Work Plan. The contribution of this research also includes that it assumes planning as a process of reducing uncertainty and maximizing throughput, counter-posing plan reliability to resource redundancy as alternative strategies for managing in conditions of uncertain work flow.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.59-66
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• 2013

Lack of the space in many diesel vehicles make it difficult to design and install the catalytic muffler to reduce emissions. For this reason, inlet part of the catalytic muffler is made of L-type which has lower flow uniformity than conventional I-type, and catalytic muffler has complex internal structure by various insertions, which affect the flow uniformity and pressure drop of the systems. In this work, the flow characteristics such as flow uniformity and pressure drop have been numerically investigated by changing such various geometries as inlet shape, porosity, and outlet shape inside the muffler with the three-dimensional turbulent incompressible flow solver. Total 4 different cases are considered in order to find optimal configurations of the catalytic muffler in view of high flow uniformity and low pressure drop. The results show that Case 2 which has no induction cone and outlet perforated pipe has higher uniformity index and lower pressure drop than others considered in this work.