• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.62-70
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• 2023

We proposed a technique for predicting Stress-Life (S-N) curve or fatigue life using geometric features of a ply-overlap joint structure in which plies of two composite materials are partially or wholly laminated and bonded. Geometric features that could affect fatigue properties of a structure were selected as variables. By analyzing relationships between geometric variables and material constants of the Epaarachchi-Clausen model, a fatigue model for composites, relational expressions of these two factors were proposed. To verify the prediction accuracy of the proposed method, fatigue life of a CFRP/GFRP ply-overlap joint was predicted. Predicted life and life obtained by test data-based model were compared to actual life. High prediction accuracy was confirmed by calculating the coefficient of determination of the predicted S-N curve.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.2
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• pp.131-156
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• 1998

Cooperative query answering is a research effort to develop a fault-tolerant and intelligent database system using the semantic knowledge base constructed from the underlying database. Such knowledge base has two aspects of usage. One is supporting the cooperative query answering Process for providing both an exact answer and neighborhood information relevant to a query. The other is supporting ongoing maintenance of the knowledge base for accommodating the changes in the knowledge content and database usage purpose. Existing studies have mostly focused on the cooperative query answering process but paid little attention on the dynamic knowledge base maintenance. This paper proposes a multi-level knowledge representation framework called Knowledge Abstraction Hierarchy (KAH) that can not only support cooperative query answering but also permit dynamic knowledge maintenance. The KAH consists of two types of knowledge abstraction hierarchies. The value abstraction hierarchy is constructed by abstract values that are hierarchically derived from specific data values in the underlying database on the basis of generalization and specialization relationships. The domain abstraction hierarchy is built on the various domains of the data values and incorporates the classification relationship between super-domains and sub-domains. On the basis of the KAH, a knowledge abstraction database is constructed on the relational data model and accommodates diverse knowledge maintenance needs and flexibly facilitates cooperative query answering. In terms of the knowledge maintenance, database operations are discussed for the cases where either the internal contents for a given KAH change or the structures of the KAH itself change. In terms of cooperative query answering, database operations are discussed for both the generalization and specialization Processes, and the conceptual query handling. A prototype system has been implemented at KAIST that demonstrates the usefulness of KAH in ordinary database application systems.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.15-22
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• 2020

The 4th industrial revolution and the rapid change in the data environment revealed technical limitations in the existing relational database(RDB). As a new analysis method for unstructured data in all fields such as IDC/finance/insurance, interest in graph database(GDB) technology is increasing. The graph database is an efficient technique for expressing interlocked data and analyzing associations in a wide range of networks. This study extended the existing RDB to the GDB model and applied machine learning algorithms (pattern recognition, clustering, path distance, core extraction) to detect new abnormal signs. As a result of the performance analysis, it was confirmed that the performance of abnormal behavior(about 180 times or more) was greatly improved, and that it was possible to extract an abnormal symptom pattern after 5 steps that could not be analyzed by RDB.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.607-614
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• 2015

In this paper, structural analysis for the 16 core competencies of aircraft maintenance crew using FSM is carried out for the purpose of improving the capability of aircraft maintenance. As a result, the three groups of layers are composed of the 3 top layers, 3 middle layers and 10 lowest layers. These results make it possible to grasp the impact and importance. In addition, the core competency of aircraft maintenance crew can improve the maintenance quality and productivity through working on the spot. In this viewpoint, fuzzy relational matrix, which is used as a basis for evaluating the work, can be obtained from the data of the 100 aircraft maintenance crew for core competencies. In this paper, the efficiency of this model is shown by utilizing the 100 modeling data and the 67 checking data.

• Journal of KIISE:Databases
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• v.29 no.2
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• pp.89-98
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• 2002

As XML has become an emerging standard for information exchange on the World Wide Web it has gained attention in database communities to extract information from XML seen as a database model. Recently, many researchers have addressed the problem of storing XML data and processing XML queries using traditional database engines. Here, most of them have used relational database systems. In this paper, we show that OODBSs can be another solution. Our technique generates an OODB schema from DTDs and processes XML queries, Especially, we show that the semi-structural part of XML data can be represented by the 'inheritance' and that this can be used to improve query processing.

• Proceedings of the Korean Association for Survey Research Conference
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• 2005.12a
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• pp.221-245
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• 2005

This research introduced the concept of 'alternative attractiveness' derived from the social exchange theory to the research model predicting turnover intention among salesforce. By doing so, we tried to broaden the understandings of relationship between salesperson job attitude and salesperson behavior. We collected and analysed the data from the survey on the 178 salespeople employed at the life insurance companies. We found the alternative attractiveness to be a significant antecedent of the turnover intention. Specifically, the more attractive the alternative the greater the intention of turnover. However, we also found that the salesforces are less attracted to the alternative if they are more satisfied with their jobs. Finally, this research can be a seminary work with the relational perspective for the studies of salesforce management.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.115-124
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• 2006

XML is rapidly becoming technologies for information exchange and representation. It causes many research issues such as semantic modeling methods, security, conversion far interoperability with other models, and so on. Especially, the most important issue for its practical application is how to achieve the interoperability between XML model and relational model. Until now, many suggestions have been proposed to achieve it. However several problems still remain. Most of all, the exiting methods do not consider implicit referential integrity relations, and it causes incorrect data delivery. One method to do this has been proposed with the restriction where one semantic is defined as only one same name in a given database. In real database world, this restriction cannot provide the application and extensibility. This paper proposes a noble conversion (RDB-to-XML) algorithm based on the similarity checking technique. The key point of our method is how to find implicit referential integrity relations between different field names presenting one same semantic. To resolve it, we define an enhanced implicity referentiai integrity relations extraction algorithm based on a widely used ontology, WordNet. The proposed conversion algorithm is more practical than the previous-similar approach.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.56
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• pp.3-27
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• 2012

The purpose of this thesis is to develop a relational model which can explain consumer selection for exporting goods and analyze the effect of corporate image on the relations between country image and consumer selection under global trade environment. The specific objectives are as follows: 1) to suggest a concept of consumer selection and measurement criteria, 2) to analyze correlations among country image, corporate image and consumer selection and 3) to find out the effect of corporate image on the relations between country image and consumer selection. The SPSS program for window and LISREL program were used to analyze the data for this study. The statistical method used in this study was the covariance structure analysis estimating parameters by maximum likelihood method. Path coefficients were tested for t-tests with a statistical significance level of .05. The conclusions of this study are as follows. First, significant correlations were observed among all sub-variables proposed in this study. In addition, significant correlations were detected among country image, consumer selection and corporate image. Second, a hypothetical model proposed in this study was mostly appropriate. Country image had a positive direct effect on consumer selection and corporate image with statistical significance. In addition, it has an indirect impact on consumer selection with statistical significance with corporate image as an intervening variable. Third, corporate image had a significant moderation effect in country image-consumer selection relations. As corporate image levels increased, the effect of country image on consumer selection increased as well. In other words, it has been confirmed that if corporate image levels are high, country image could end up with consumer selection.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.103-103
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• 2000

In this paper to cope with the reduction of products life-cycle as the variety of products along with the various demands of consumers, a virtual simulator is developed to make the changeover of manufacturing line efficient to embody a virtual simulation similar to a real manufacturing line. The developed virtual simulator can design a layout of a factory and make the time scheduling. Every factory has one simulator so that one product can be manufactured in the factories to use them as virtual factories. We suggest a scheme that heightens the agility to the diversity of manufacturing models by making the information of manufacturing lines and products models to be shared. The developed unit simulator can construct a proper virtual manufacturing line along with the required process of products using several kinds of operator and work cell. A user with the simulator can utilize an interface that makes one to manage the separate task process for each manu(acturing module, change operator components and work cells, and easily teach tasks of each task module. The developed simulator was made for users convenience by Microsoft Visual C++ 6.0 that can develop a program supplying graphic user interface environment and by OpenGL of the Silicon Graphics as a graphic library to embody 3D graphic environment. Also, we show that the simulator can be used efficiently for the agile manufacturing by the communication among the factories being linked by TCP/IP and a hybrid database system made by a hierarchical model and a relational model being developed to standardize the data information.

• Journal of Information Technology Services
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• v.20 no.2
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• pp.147-166
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• 2021

As vehicle sharing service is being widely used in China. The sharing economy appeared to be a way to make people's lives more convenient and to utilize limited resources efficiently. Sharing economy companies have created an app to satisfy users' needs with providing more benefits. Although research on vehicle sharing services has been continuously conducted at the level of the sharing economy, there are not many empirical studies related to the perception of the sharing economy from the consumer's point of view. In this sense, this study considered the perceived relationship benefits (social benefits, economic benefits, psychological benefits, and functional benefits) of Didi chuxing service as the key independent variables influencing users' confirmation and satisfaction, And suggests that users' confirmation and satisfaction are the key determinants of Didi continuance intention . To test the proposed research model, this study conducted structural equation model using 268 data collected on the users who have experience of Didi service. According to the empirical analysis results, This study verifies that: First, social benefits, economic benefits, psychological benefits, and functional benefits are determinants of user's satisfaction. Second, expectation confirmation depends on economic benefits, psychological benefits, functional benefits and social influence, meanwhile, social benefit has no effect on expectation confirmation. Third, expectation confirmation is proved to be a positive predictor of users' satisfaction. Finally, this results indicate that continuous use intention is determined by users' satisfaction.