• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.41-47
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• 2012

There are PFD(Process Flow Diagram) and P&ID(Piping and Instrument Diagram) for designing and managing chemical process efficiently. They provide the operation condition and equipment specifications of chemical process, but they do not provide the reliability of chemical process. Therefore, in this study, Reliability Flow Diagram(RFD) which provide the cycle and time of preventive maintenance has been developed using Directed Graph Analysis methodology. Directed Graph Analysis methodology is capable of assessing the reliability of chemical process. It models chemical process into Directed Graph with nodes and arcs and assesses the reliability of normal operation of chemical process by assessing Directed Graph sequential. In this paper, the chemical process reliability transition according to operation time was assessed. And then, Reliability Flow Diagram has been developed by inserting the result into P&ID. Like PFD and P&ID, Reliability Flow Diagram provide valuable and useful information for the design and management of chemical process.

• Journal of the Korea Society for Simulation
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• v.22 no.4
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• pp.109-118
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• 2013

This paper adopts the system configuration to assess the reliability instead of making a fault tree (FT), which is a traditional method to analyze reliability of a certain system; this is the reliability block diagram (RBD) method. The RBD method is a graphical presentation of a system diagram connecting the subsystems of components according to their functions or reliability relationships. The equipment model for the reliability simulation is modeled based on the discrete event system specification (DEVS) formalism. In order to make various alternatives of target system, this paper also adopts the system entity structure (SES), an ontological framework that hierarchically represents the elements of a system and their relationships. To enhance the calculation time of reliability analysis, GPU-based accelerations are adopted to the reliability simulation.

• Archives of design research
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• v.19 no.5 s.67
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• pp.75-84
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• 2006

The aims of this study are to examine the conceptual contents of space diagram, and to find its elements and practical applications by analyzing the UN Studio. The Findings of this study are as follows: firstly, the conceptual contents represented in space diagram are classified into four elements - motif, flow, relationship, and distribution. Secondly, space diagram is used in program development, schematic design, and preliminary design of design process phases. Thirdly, the elements based on the case diagrams include five elements: context analysis, object analysis, time-behavior analysis, modeling analysis, and space analysis. Fourthly, in practical use, diagrams with motif concept is usually used in modeling analysis, and diagram with flow concept is commonly used in the analysis of time-behavior and object. Diagrams with relationship concept is mostly used in space analysis, secondly in analysis of context and modeling. Further, diagrams with distribution concept is usually used in space analysis. If one uses these findings for design projects in practical business or education, it would be helpful in design conception and development as well as of design information structuralization.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.149-158
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• 2010

A messenger program in this paper was designed and implemented using Use Case Diagram, Class Diagram, Activity Diagram, and Sequence Diagram. We selected total 7 major functionalities such as PC server, login, friends management, chatting, file transfer, account management, etc. The followings are various implementation results from this paper. First, developers could easily understand the desired product and programming flow from using UML Diagrams. Second, PDA users could communicate with developers for a long time without time constraints. Third, there was high usability of UML Diagram in the phase of objected-oriented analysis. Forth, it was easy to update and maintain a program.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.183-190
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• 2012

PURPOSES : The fundamental diagram provides basic information necessary in the analysis of traffic flow and highway operation. When traffic flow is congested, the density-flow points in the fundamental diagram are widely scattered and move in a stochastic manner. This paper investigates the pattern of density-flow point transitions and identifies car-following behaviors underlying the density-flow transitions. METHODS : From a microscopic analysis of 722 fundamental diagrams of NGSIM data, a total of 20 transition patterns of fundamental diagrams are identified. Prominent features of the transition patterns are explained by the behavior of the leader and follower. RESULTS : It is found out that the average speed and the speed difference between the leader and the follower critically determine the density-flow transition pattern. The density-flow path is very sensitive to the values of vehicle speed and spacing especially at low speed and high density such that most fluctuations in the fundamental diagram in the congested regime is due to the noise of speed and spacing variations. CONCLUSIONS : The result of this study suggests that the average speed, the speed difference between the leader and the follower, and the random variations of speed and spacing are dominant factors that explain the transition patterns of a fundamental diagram.

• Transactions of Materials Processing
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• v.15 no.6 s.87
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• pp.467-472
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• 2006

The forming limit diagram of tube is required for the part design and the formability analysis of tube hydroforming. The finite element analyses of simple bulge test were done to obtain the various strain combinations on FLC. The finite element analysis results were shown that the bursting at various strain combinations could be induced by simple bulge test. The experiment oi tube bulge test was carried out according to the test condition that obtained from finite element analysis and the left hand side of forming limit diagram was built.

• Asia pacific journal of information systems
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• v.7 no.1
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• pp.99-111
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• 1997

This paper presents an application of an artificial neural net to the implementation of decision class analysis (DCA), together with the generation of a decision model influence diagram. The diagram is well-known as a good tool for knowledge representation of complex decision problems. Generating influence diagram model is known to in practice require much time and effort, and the resulting model can be generally applicable to only a specific decision problem. In order to reduce the burden of modeling decision problems, the concept of DCA is introduced. DCA treats a set of decision problems having some degree of similarityz as a single unit. We propose a method utilizing a feedforward neural net with supervised learning rule to develop DCA based on influence diagram, which method consists of two phases: Phase l is to search for relevant chance and value nodes of an individual influence diagram from given decision and specific situations and Phase II elicits arcs among the nodes in the diagram. We also examine the results of neural net simulation with an example of a class of decision problems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.57-62
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• 2007

A modeling method for the modal and the transient vibration analysis of a multi-packet blade system excited by nozzle jet forces is presented in this paper. Blades are idealized as cantilever beams and the elastic structures like disc and shroud connecting blades are modeled as coupling stiffnesses. A modified Campbell diagram is proposed to identify true resonance frequencies of the multi-packet blade system. Different from the SAFE diagram that employs three dimensional space, the modified Campbell diagram proposed in this study employs a plane to find the true resonance frequencies. To verify the existence of true resonance frequencies, nozzle jet forces are modeled as periodic forces and transient vibration analysis were performed with the modeling method.

• IE interfaces
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• v.17 no.2
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• pp.200-207
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• 2004

Because the designed workflow may contain potential errors which may result in deadlocks, livelocks and so on, it is important to analyze the correctness of a workflow definition before it is put into the run time environment. Proposed in this paper is a transformation procedure of an UML activity diagram into a Petri net for the analysis of a workflow. By combining the strengths of easy-to-use functionality of an activity diagram and the analysis power of a Petri net, workflow analysts in the enterprise can model and analyze various kinds of workflow definition more easily and accurately.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.7
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• pp.711-717
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• 2008

A modeling method for the modal and the transient vibration analysis of a multi-packet blade system excited by nozzle jet forces is presented in this paper. Blades are idealized as cantilever beams and the elastic structures like disc and shroud connecting blades are modeled as coupling stiffnesses. A modified Campbell diagram is proposed to identify true resonance frequencies of the multi-packet blade system. Different from the SAFE diagram that employs three dimensional space, the modified Campbell diagram Proposed in this study employs a plane to find the true resonance frequencies. To verify the existence of true resonance frequencies, nozzle jet forces are modeled as periodic forces and transient vibration analysis were performed with the modeling method.