Injun Choi

On resolving schematic heterogeneity in multidatabase systems

The objective of a multidatabase system is to provide a single uniform interface to accessing multiple independent databases being managed by multiple independent, and possibly heterogeneous, database systems. One crucial element in the design of a multidatabase system is the design of a data definition language for specifying a schema that represents the integration of the schemas of multiple independent databases. The design of such a language in turn requires a comprehensive classification of the conflicts (i.e., discrepancies) among the schemas of the independent databases and development of techniques for resolving (i.e., homogenizing) all of the conflicts in the classification. An earlier paper provided a comprehensive classification of schematic conflicts that may arise when integrating multiple independent relational database (RDB) schemas into a single multidatabase (MDB) schema. In this paper, we provide a comprehensive classification of techniques for resolving the schematic conflicts that may arise when integrating multiple RDB schemas, or RDB schemas and object-oriented database (OODB) schemas, or multiple OODB schemas. The classification of conflict resolution techniques includes not only those necessary for resolving schematic conflicts identified in the earlier paper, but also additional conflicts that arise when OODBs become part of the databases to be integrated. Most of the conflict resolution techniques discussed in the paper have already been incorporated into SQL/M, a multidatabase language implemented in UniSQL/M, a commercially available multidatabase system from UniSQL, Inc. which integrated SQL-based relational database systems and the UniSQL/X unified relational and object-oriented database system.

An integration architecture for knowledge management systems and business process management systems

Recently, interests in the notion of process-oriented knowledge management (PKM) from academia and industry have been significantly increased. Comprehensive research and development requirements along with a cogent framework, however, have not been proposed for integrating knowledge management (KM) and business process management (BPM), which were proposed independently. Based on a comprehensive framework that reflects lifecycle requirements of both KM and BPM, this paper proposes an architecture for integrating knowledge management systems (KMSs) and business process management systems (BPMSs) to combine the advantages of the two paradigms. The paper first defines the concept of process knowledge and classifies it into three types. Then, it suggests how the functionalities of existing KMSs and BPMSs must be extended to support the three types of process knowledge while satisfying the lifecycle requirements of both knowledge and business processes. The architecture, which is comprehensive since it is derived from the extended requirements from the lifecycle perspective, will provide a basis for research and development of process-oriented knowledge management systems. A prototype system is presented to demonstrate the feasibility of the proposed architecture.

STEP-compliant CNC system for turning: Data model, architecture, and implementation

STEP-NC, a new data model for CAD-CAM-CNC chain, is expected to encompass the whole scope of e-manufacturing. The new data model formalized as ISO 14649 is under development by ISO TC184 SC1 and SC4 for the replacement of the old standard so-called G&M codes, formalized as ISO 6983 which has been used since the 1950s. As the new data model is being established, development and implementation of STEP-compliant CAD/CAM/CNC system based on the new data model is drawing worldwide attention. Several systems have been reported in such international conventions as the ISO Expert Committee Meeting. Up to the present time, all the STEP-CNC systems are intended for milling operation. In this paper, the authors first present STEP-compliant CNC system for turning system including the data model, followed by a generic architecture and functionality. Implementation results obtained from a prototype system called TurnSTEP have been provided. Based on the results, the authors are convinced of the validity of the STEP-NC data model together with the effectiveness of the STEP-CNC system for turning.

Efficiency evaluation of data warehouse operations

We evaluate an efficiency model for data warehouse operations using data from USA and non-USA-based (mostly Korean) organizations. The analysis indicates wide dispersions in operational efficiency, industry and region differences, large differences in labor budgets between efficient and inefficient firms, few organizations efficient in both refresh processing and query production, and difficulty of providing some variables. Follow-up interviews provide insights about the value of efficiency comparisons of information technology organizations and suggestions to improve the model. Using this analysis, we propose a framework containing data warehouse characteristics and firm characteristics to explain IT operational efficiency at the subfirm level.

An XML-based process definition language for integrated process management

Business processes are increasingly recognized as important corporate assets that need to be managed throughout their lifecycle. Specially, interests in supply chain management and virtual enterprises require a new paradigm that provides lifecycle support for business processes. Integrated Process Management (IPM) has been proposed as a business process management paradigm that aims at integrating processes using eXtensible Markup Language (XML) and supporting design, analysis, automation, and management of business process knowledge. This paper introduces IPM-PDL, an XML-based process definition language for IPM. Process definitions and related data are integrated using XML which will be translated to a colored Petri Net. Various analysis and simulation can be performed to check the validity of a new process and estimate its performance. The paper also introduces ProcessWare, a prototype system for IPM-process definition language (PDL), along with an extended example which will demonstrate how IPM can effectively manage business processes throughout their lifecycle ranging from process modeling to process knowledge management.

A framework for the integration of knowledge management and business process management

Knowledge management (KM) has been considered as a new corporate information system paradigm for knowledge-intensive enterprises of the information age. Its acceptance by the corporate world, however, is below expectation. Recently, several attempts have been made to combine KM with business process management (BPM) that is a new approach to effectively managing business processes as corporate assets. Clear descriptions about their interrelationship or a comprehensive framework to combine them, however, has not been provided. This paper explores how KM and BPM can complement each other and proposes a framework to integrate the two paradigms. The paper classifies process knowledge into three types and suggests how they can extend the functionalities of existing knowledge management systems and business process management systems by considering the lifecycle requirements of both knowledge and business processes. The framework and extended functionalities can provide a new corporate paradigm that combines the advantages of KM and BPM. Further, important corporate knowledge about business processes can be defined and managed in a single framework.

Task net: Transactional workflow model based on colored Petri net

Abstract Workflow management systems are increasingly identified as a tool that cannot only integrate existing computer applications but also dynamically change existing business processes. Unlike database transactions that have a mechanism to guarantee consistency against failures or concurrent execution, there is no known mechanism that guarantees safety of workflow transactions. Therefore, capability to forecast the effects of workflow transactions is very important. That is, a model is required which allows to determine whether a workflow transaction can terminate, whether it is free from dead lock, whether it can recover from error or crash, etc. In this paper, we propose Task net which is a transactional workflow model based on colored Petri net. First, we introduce a workflow specification language that can express task state dependency relationships such as forward, backward, and mutual exclusion among intra-task states (states of the same task) and inter-task states (states of different tasks). The proposed workflow language will enable the users to express both the transaction- and application-oriented requirements of complex business rules. We, then, describe how a basic workflow specification and its task state dependencies are translated to a Task net which will allow simulation of the given workflow. Before executing a Task net, tests for deadlocks and redundant task state dependencies are performed to prevent futile efforts. Task nets are expected to provide a theoretically sound basis for current workflow systems to expand their transactional workflow supports.

Graph interpretation of methods: a unifying framework for polymorphism in object-oriented programming

We discuss two interpretations of methods and classes in object-oriented programming and demonstrate a type system based on the notion of methods as graphs. Definitionally, a class may be viewed as a data structure associated with either a collection of method interfaces or a collection of individual methods. In the former interpretation, a method represents a collection of functions that satisfy its interface known as a function space. In the latter interpretation, a method represents a set of input-output pairs of a specific function, called the functions graph. We informally describe and contrast these interpretations with particular emphasis on subtyping rules for methods --- an anti-monotonic rule for the function space interpretation and a monotonic rule for the graph interpretation. These rules have practical implications on type checking, method redefinition, assertions, dynamic binding, and completeness of subtype testing. We present a notation based on the latter interpretation and demonstrate several interesting features of our notation including abstract data types for encapsulation, four kinds of ad-hoc polymorphism (disjoint overloading, coercion, incremental overloading, and specialization), and type restrictions to precisely define the relationship among arguments in polymorphic methods.

Propagation of engineering changes to multiple product data views using history of product structure changes

The present paper proposes a comprehensive procedure for engineering change propagation in order to maintain consistency between various product data views. A product data model is also proposed for the propagation procedure, which integrates base product definitions for product design, and product data views for other manufacturing or customer support. The product data view in the proposed model enables manufacturing or customer support engineers to define their own product data views, without copying the existing product definition. Integrated with other components, the engineering changes in the data model provide structure-oriented change history, effectivity management for production, and integration with product configurations. Based on the integrated product data model, the proposed procedure propagates engineering changes to product data views using the history of product structure changes. The propagation procedure maintains consistency of product data during collaboration between various design, manufacturing and customer support departments, who have different product data views. Prototype database applications together with an example of illustrative change propagation are also presented.

Development process and data management of TurnSTEP, a STEP-compliant CNC system for turning

TurnSTEP is one of the earliest STEP-compliant CNC systems for turning. Based on the STEP-NC data model formalized as ISO 14649-12 and 121, it is designed to support intelligent and autonomous control of NC machines for e-manufacturing. The present paper introduces the development process and data management capability of TurnSTEP. After the overall architecture of the system is presented, the paper discusses the development process of TurnSTEP. Then, it describes the TurnSTEP repository that enables sharing product information anytime, anywhere, on any platform which is an important requirement for e-manufacturing. In addition, the paper presents a method to express STEP data using XML as a core technology of the repository. Since XML is a standard format for data exchange on the web, it is indispensable for the repository to support XML. This method uses only the extension mechanism supported by XML schema to express complex data structures in EXPRESS. It enables product data to be easily stored and shared across the web. Finally, the paper introduces a translator, using the method, which converts STEP data in the clear text format into XML and vice versa.