• Journal of Environmental Science International
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• v.17 no.9
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• pp.957-968
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• 2008

The purpose of this study is to analyze the characteristics of hydraulic behavior of the natural channel flow according to the temporal classification mode, and thus propose the hydraulic analysis method for future channel design. For analysis, the temporal flow characteristics of the channel section was divided into the steady flow and the unsteady flow. For hydraulic analysis, the HEC-RAS model, which is a one-dimensional numerical analysis model, and the SMS-RAM2 model, which is a two-dimensional model, were used and the factors used for analysis of hydraulic characteristics were flood elevation and flow rate. The flow state was analyzed on the basis of the one-dimensional steady flow and unsteady flow for review. In the unsteady flow analysis the flow rate changed by $(-)0.16%{\sim}(+)0.26%$, and the flood elevation varied by $(-)0.35%{\sim}(+)0.51%$ as compared to the values in the steady flow analysis. Given these results, in the one-dimensional flow analysis based on the unsteady flow the flood elevation and flow rate were greater than when the analysis was done on the basis of the steady flow. The flow state was analyzed on the basis of the two-dimensional steady flow and unsteady flow. In the unsteady flow analysis the flow rate varied by $(-)0.16%{\sim}(+)1.08%$, and the flood elevation changed by $(-)0.24%{\sim}(+)0.41%$ as compared to the values in the steady flow analysis. Given these analysis results, in the two dimensional flow analysis based on the unsteady flow, the flood elevation and flow rate were greater than when the analysis was done on the basis of the steady flow.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2032-2041
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• 2004

Results from an experimental study of flow distribution in a close-coupled catalytic converter(CCC) are presented. The experiments were carried out with a flow measurement system specially designed for this study under steady and transient flow conditions. A pitot tube was a tool for measuring flow distribution at the exit of the first monolith. The flow distribution of the CCC was also measured by LDV system and flow visualization. Results from numerical analysis are also presented. Experimental results showed that the flow uniformity index decreases as flow Reynolds number increases. In steady flow conditions, the flow through each exhaust pipe made some flow concentrations on a specific region of the CCC inlet. The transient test results showed that the flow through each exhaust pipe in the engine firing order, interacted with each other to ensure that the flow distribution was uniform. The results of numerical analysis were qualitatively accepted with experimental results. They supported and helped explain the flow in the entry region of CCC.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.419-424
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• 2002

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality In February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. A flow simulation facility is being developed for the endurance test of reactivity control units for extended life times and the verification of structural integrity of those experimental facilities prior to loading in the HANARO. This test facility is composed of three major parts; a half-core structure assembly, flow circulation system and support system. The flow circulation system is composed of a circulation pump, a core flow pipe, a core bypass flow pipe and instruments. The system is to be filled with de-mineralized water and the flow should be met the design flow to simulate similar flow characteristics in the core channel of the half-core test facility to the HANARO. This paper, therefore, describes an analytical analysis to study the flow behavior of the system. The computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with standard k-$\epsilon$ turbulence model and for the verification of the structural piping integrity through the finite element method. The results of the analysis are satisfied the design requirements and structural piping integrity of flow circulation system.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.30-35
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• 2004

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. HANARO flow simulation facility is being developed for the endurance test of reactivity control units for extended life time and the verification of structural integrity of those experimental equipments prior to loading in the HANARO. This facility is composed of three major parts; a half-core structure assembly, a flow circulation system and a support system. The flow circulation system is composed of a circulation pump, a core flow piping, a core bypass flow piping and instruments. The system is to be filled with de-mineralized water and the flow should be met the design requirements to simulate a similar flow characteristics in the core channel of the half-core structure assembly to the HANARO. This paper, therefore, presents an analytical analysis to study the flow behavior of the system. Computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with the standard $k-{\epsilon}$ turbulence model and for the verification of the structural piping integrity through the finite element method. According to the analysis results, it could be said that the design requirements and the structural piping integrity of the flow circulation system are satisfied.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.3
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• pp.87-98
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• 2009

This paper discuss secure information flow analysis and its visualization. Information leak is defined as existence of information flow from variables which have user's private informations to variables that anyone can access. Secure information flow analysis has been made to decide of whether the information leak is or not. There are many researches for secure information flow analysis concerning high level programming languages. But actually, programs that user executes don't have program source code represented in high level programming language. Thus there is need for analysis of program represented in low level language. More to analysis, visualization of analysis is very important. So, this paper discuss visualization of secure information flow analysis. In this paper, Mini x86 Assembly Language which is subset of x86 assembly language is defined and secure information flow analysis of program is proposed. In addition, this paper defines transfer function that is used for analysis and shows how to visualize control flow graph.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.435-447
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• 2019

Energy Flow Finite Element Analysis (EFFEA) is a promising tool for predicting dynamic energetics of complicated structures at high frequencies. In this paper, the Energy Flow Finite Element (EFFE) formulation of complicated Mindlin plates was newly developed to improve the accuracy of prediction of the dynamic characteristics in the high frequency. Wave transmission analysis was performed for all waves in complicated Mindlin plates. Advanced Energy Flow Analysis System (AEFAS), an exclusive EFFEA software, was implemented using $MATLAB^{(R)}$. To verify the general power transfer relationship derived, wave transmission analysis of coupled semi-infinite Mindlin plates was performed. For numerical verification of EFFE formulation derived and EFFEA software developed, numerical analyses were performed for various cases where coupled Mindlin plates were excited by a harmonic point force. Energy flow finite element solutions for coupled Mindlin plates were compared with the energy flow solutions in the various conditions.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.199-207
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• 2020

These days, many different types of valves are developed in the industrial area according to their use purpose. Multiple kinds of valves are installed to control a flow and pressure of the pipe conveying fluid. Valves serve as critical roles in land plants such as power plants. The performance of equipment varies depending on valve characteristics. In this study, the internal flow analysis on Cone-type valve is conducted to analyze flow field and secure a value of the flow coefficient Cv. According to the internal flow analysis, when the flow distribution of the middle cross-section of valve was open 100%, flow field was relatively and smoothly taken out. If it was open 50%, flow recirculation region increased and a little complex flow field occurred. Unlike ball valve or butterfly valve, this valve had flow recirculation in its outlet depending on a valve opening amount. Therefore, it was found that there was no flow recirculation in the outlet of Cone-type valve.

• Journal of KIISE:Software and Applications
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• v.31 no.5
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• pp.643-650
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• 2004

Control flow graph is used for Performing many Program-analysis techniques, such as data-flow and control-dependence analysis, and software-engineering techniques, such as program slicing and testings. For these analyses to be safe and useful, the CFG should incorporate the exception flows that are induced by exceptions. In previous research to construct control flow graph, normal flows and exception flows are computed at the same time, since these two flows are known to be mutually dependent. By investigating realistic Java programs, we found that the cases when these two flows are mutually dependent rarely happen. So, we can decouple exception flow analysis from normal flow analysis. In this paper we propose an analysis that estimates exception flows. We also propose exception flow graph to represent exception flows. And we show that the control flow graph that accounts for exception flows can be constructed by merging exception flow graph onto normal control flow graph.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1221-1225
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• 2008

In this paper, analysis of pressure and flow characteristics have been performed with a servo valve. A number of servo valve have been used in various applications including the inserting device, bearing transportation and welding machine. By analysis of flow and pressure gradient, technology can be obtained about optimal simulation of high response servo valve for competitiveness. Spool displacement and ratio of inlet/outlet pressure can give big effects to flow and pressure inside servo valve.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.1
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• pp.23-27
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• 2007

This article presents a review on chaos analysis of two-phase flow. Chaos theory has recently been applied to two-phase flow analysis, and it gives promising measures to quantitatively identify two-phase flow patterns and pool boiling behaviors. But, consistency of the calculated chaotic measures were not completely confirmed yet. More experimental data are requested for chaos analysis of two-phase flow. Also, chaos analysis methodology should be developed by experimental verification.