• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.208-216
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• 2003

ISO 14649 (data model for STEP-NC) is a new interface scheme or language for CAD-CAM-CNC chain under established by ISO TC184 SCI. Up to this point, the new language is mainly made for milling and turning, and other processes such as EDM will be completed in the future. Upon completion, it will be used as the international standard language for e-manufacturing paradigm by replacing the old machine-level language, so called M&G code used since 1950's. With the rich information contents included in the new language, various intelligent functions can be made by the CNC as the CNC knows what-to-make and how-to-make. In particular, On-Machine Inspection required for quality assurance in the machine level, can be done based on the information of feature­based tolerance graph. Previously, On-Machine inspection has been investigated mainly for milling operation, and only a few researches were made for turning operation without addressing the data model. In this thesis, we present a feature-based on-machine inspection process by the 4 Tasks: 1) proposing a new schema for STEP-NC data model, 2) converting the conventional tolerance scheme into that of STEP-NC, 3) modifying the tolerance graph such that the tolerance can be effectively measured by the touch probe on the machine, and 4) generating collision-free tool path for actual measurement. Task 1 is required for the incorporation of the presented method in the ISO 14649, whose current version does not much include the detailed schema for tolerance. Based on the presented schema, the tolerance represented in the conventional drafting can be changed to that of STEP-NC (Task 2). A special emphasis was given to Task 3 to make the represented tolerance accurately measurable by the touch probe on the machine even if the part setup is changed. Finally, Task 4 is converting the result of Task into the motion of touch probe. The developed schema and algorithms were illustrated by several examples including that of ISO 14649 Part 12.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.82-92
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• 1998

An international standard for the product model data, STEP, and a standard for the distributed object technology, CORBA, will play a very important role in the future manufacturing environment. These two technologies provide background for the sharing of product data and the integration of applications on the network. This paper describes a prototype CAD/CAE environment that is integrated on the network by STEP and CORBA. Several application servers and client software were developed to verify the proposed concept. The present CAD/CAE environments are composed of several individual software components which are not tightly integrated. They also do not utilize the rapidly expanding network and object technologies for the collaboration in the product design process. In the design process in a large organization, sharing of application resources, design data and analysis data through the network will greatly enhance the productivity. The integration between applications can be supported by two key technologies, CORBA(Common Object Request Broker Architecture) and STEP(Standard for the Exchange of Product Model Bata). The CORBA provides interoperability between applications on different machines in heterogeneous distributed environments and seamlessly interconnects distributed object systems. Moreover, if all the data in the CAD/CAE environment are based on the STEP, then we can exclude all the data conversion problems between the application systems.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.49-64
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• 1991

In this paper, we present a stepwise design methodology for relational databases using a new conceptual data model, the MAO(Multiple Aspects-based Object) model. Our methodology consists two steps : first, data requirements are conceptualized using the MAO model with concepts such as objects types and aspect types : second, the MAO model is transformed into the third normal form inn the relational model supported by commercial DBMs. A top-down approach is used for the MAO modelling in the first, step, and the transformation process in the second step can be automated. Our methodology supports easier and more database design of real world than other methodologies using existing data models.

• Korean Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.48-56
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• 1998

Finite element analysis is very important in the design and analysis of mechanical engineering. The process of FEA encompasses shape modeling, mesh generation, matrix solving and post-processing. Some of these processes can be tightly integrated with the current software architectures and data sharing mode. However, complete integration of all the FEA process itself and the integration to the manufacturing processes is almost impossible in the current practice. The barriers to this problem are inconsistent data format and the enterprise-wise software integration technology. In this research, the information model based on STEP AP209 was chosen for handling finite element analysis data. The international standard for the FEA data can bridge the gap between design, analysis and manufacturing processes. The STEP-based FEA system can be further tightly integrated to the distributed software and database environment using CORBA technology. The prototype FEA system DICESS is implemented to verify the proposed concepts.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.105-117
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• 2004

In each industry field, many engineers have tried to develop integrated environments using information technology. The core technology in building integrated environments is the database based on standardized information. To meet the requirements, this study builds a database with detailed design information as a part of integrating digital information generated from every work of steel bridges. The data model used to build the database was developed based on the international standard, namely ISO/STEP. The data model is classified into geometric and non-geometric parts to represent the design information of steel bridges. The geometric parts are represented by a three dimensional solid model so that they may be able to reuse existing information. Also, the non-geometric parts represent information requirements that are analyzed by the development method of standard data model. To verify the data model, this study validates the syntax of the model on EXPRESS Engine and verifies the validation of the model by applying the design data of Hannam bridge to the database.

• Korean Journal of Computational Design and Engineering
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• v.10 no.3
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• pp.179-187
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• 2005

The usage of mixed 2D and 3D CAD data of commercial CAD systems is required in the construction practice. Sometimes 3D wireframe model is required by end-users when 2D CAD data is delivered. However, current KOSDIC can not represent 3D CAD data, because it has been developed as a 2D drawing delivery standard. Therefore, this study is to provide exchange and sharing of mixed 2D and 3D CAD data that add 3D wireframe model in the KOSDIC. To achieve this purpose, the authors have investigated the 3D CAD entities of commercial CAD systems, and have analyzed STEP standards providing 3D wireframe model. The result, the authors have extracted 3D CAD common entities based wireframe model which shall be added in the KOSDIC. This study can be beneficial by using the developed data model for heterogeneous CAD systems, and by providing the representation of mixed 2D and 3D CAD data in construction practice such as GIS, piping system, and so forth.

• Asia-Pacific Journal of Atmospheric Sciences
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• v.54 no.4
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• pp.611-622
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• 2018

Observed climate data are processed under the assumption that their time series are stationary, as in multi-step temperature and precipitation prediction, which usually leads to low prediction accuracy. If a climate system model is based on a single prediction model, the prediction results contain significant uncertainty. In order to overcome this drawback, this study uses a method that integrates ensemble prediction and a stepwise regression model based on a mean-valued generation function. In addition, it utilizes empirical mode decomposition (EMD), which is a new method of handling time series. First, a non-stationary time series is decomposed into a series of intrinsic mode functions (IMFs), which are stationary and multi-scale. Then, a different prediction model is constructed for each component of the IMF using numerical ensemble prediction combined with stepwise regression analysis. Finally, the results are fit to a linear regression model, and a short-term climate prediction system is established using the Visual Studio development platform. The model is validated using temperature data from February 1957 to 2005 from 88 weather stations in Guangxi, China. The results show that compared to single-model prediction methods, the EMD and ensemble prediction model is more effective for forecasting climate change and abrupt climate shifts when using historical data for multi-step prediction.

• Nuclear Engineering and Technology
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• v.28 no.3
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• pp.299-310
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• 1996

A two-step approach has been used to obtain a new criterion for the onset of slug formation : (1) In the first step, a more general expression than the existing models for the onset of slug flow criterion has been derived from the analysis of singular points and neutral stability conditions of the transient one-dimensional two-phase flow equations of two-fluid model. (2) In the second step, introducing simplifications and incorporating a parameter into the general expression obtained in the first step to satisfy a number of physical conditions a priori specified, a new simple criterion for the onset of slug flow has been derived. Comparisons of the present model with existing models and experimental data show that the present model agrees very closely with Taitel & Dukler's model and experimental data in horizontal pipes. In an inclined pipe ($\theta$ =50$^{\circ}$), however, the difference between the predictions of the present model and those of existing models is appreciably large and the present model gives the best agreement with Ohnuki et al.'s data.

• IE interfaces
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• v.10 no.3
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• pp.23-31
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• 1997

Exchange of product model data becomes a key issue in the globalized enterprise environment. Sharing heterogeneous information resides in diverse information resources is not easy. To share automotive product information among different organizations, a reliable neutral information standard and communication methods are needed. World wide sharing of automotive product information can be implemented based on the STEP AP214, the standard for exchange of automotive product model through its whole life cycle. This paper suggests an automotive PDM implemented on the internet and based on the STEP AP214. Physical files containing design data can be shared on the internet using JAVA applets and VRML.

• Food Science of Animal Resources
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• v.43 no.2
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• pp.374-381
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• 2023

In a previous study, 'response surface methodology (RSM) using a fullest balanced model' was proposed to improve the optimization of food processing when a standard second-order model has a significant lack of fit. However, that methodology can be used when each factor of the experimental design has five levels. In response surface experiments for optimization, not only five-level designs, but also three-level designs are used. Therefore, the present study aimed to improve the optimization of food processing when the experimental factors have three levels through a new approach to RSM. This approach employs three-step modeling based on a second-order model, a balanced higher-order model, and a balanced highest-order model. The dataset from the experimental data in a three-level, two-factor central composite design in a previous research was used to illustrate three-step modeling and the subsequent optimization. The proposed approach to RSM predicted improved results of optimization, which are different from the predicted optimization results in the previous research.