• Korean Circulation Journal
• /
• v.52 no.12
• /
• pp.853-864
• /
• 2022

A retrospective observational study is one of the most widely used research methods in medicine. However, evidence postulated from a single data source likely contains biases such as selection bias, information bias, and confounding bias. Acquiring enough data from multiple institutions is one of the most effective methods to overcome the limitations. However, acquiring data from multiple institutions from many countries requires enormous effort because of financial, technical, ethical, and legal issues as well as standardization of data structure and semantics. The Observational Health Data Sciences and Informatics (OHDSI) research network standardized 928 million unique records or 12% of the world's population into a common structure and meaning and established a research network of 453 data partners from 41 countries around the world. OHDSI is a distributed research network wherein researchers do not own or directly share data but only analyzed results. However, sharing evidence without sharing data is difficult to understand. In this review, we will look at the basic principles of OHDSI, common data model, distributed research networks, and some representative studies in the cardiovascular field using the network. This paper also briefly introduces a Korean distributed research network named FeederNet.

• Journal of Intelligence and Information Systems
• /
• v.19 no.1
• /
• pp.111-123
• /
• 2013

Semantic similarity/relatedness measure between two concepts plays an important role in research on system integration and database integration. Moreover, current research on keyword recommendation or tag clustering strongly depends on this kind of semantic measure. For this reason, many researchers in various fields including computer science and computational linguistics have tried to improve methods to calculating semantic similarity/relatedness measure. This study of similarity between concepts is meant to discover how a computational process can model the action of a human to determine the relationship between two concepts. Most research on calculating semantic similarity usually uses ready-made reference knowledge such as semantic network and dictionary to measure concept similarity. The topological method is used to calculated relatedness or similarity between concepts based on various forms of a semantic network including a hierarchical taxonomy. This approach assumes that the semantic network reflects the human knowledge well. The nodes in a network represent concepts, and way to measure the conceptual similarity between two nodes are also regarded as ways to determine the conceptual similarity of two words(i.e,. two nodes in a network). Topological method can be categorized as node-based or edge-based, which are also called the information content approach and the conceptual distance approach, respectively. The node-based approach is used to calculate similarity between concepts based on how much information the two concepts share in terms of a semantic network or taxonomy while edge-based approach estimates the distance between the nodes that correspond to the concepts being compared. Both of two approaches have assumed that the semantic network is static. That means topological approach has not considered the change of semantic relation between concepts in semantic network. However, as information communication technologies make advantage in sharing knowledge among people, semantic relation between concepts in semantic network may change. To explain the change in semantic relation, we adopt the cognitive semantics. The basic assumption of cognitive semantics is that humans judge the semantic relation based on their cognition and understanding of concepts. This cognition and understanding is called 'World Knowledge.' World knowledge can be categorized as personal knowledge and cultural knowledge. Personal knowledge means the knowledge from personal experience. Everyone can have different Personal Knowledge of same concept. Cultural Knowledge is the knowledge shared by people who are living in the same culture or using the same language. People in the same culture have common understanding of specific concepts. Cultural knowledge can be the starting point of discussion about the change of semantic relation. If the culture shared by people changes for some reasons, the human's cultural knowledge may also change. Today's society and culture are changing at a past face, and the change of cultural knowledge is not negligible issues in the research on semantic relationship between concepts. In this paper, we propose the future directions of research on semantic similarity. In other words, we discuss that how the research on semantic similarity can reflect the change of semantic relation caused by the change of cultural knowledge. We suggest three direction of future research on semantic similarity. First, the research should include the versioning and update methodology for semantic network. Second, semantic network which is dynamically generated can be used for the calculation of semantic similarity between concepts. If the researcher can develop the methodology to extract the semantic network from given knowledge base in real time, this approach can solve many problems related to the change of semantic relation. Third, the statistical approach based on corpus analysis can be an alternative for the method using semantic network. We believe that these proposed research direction can be the milestone of the research on semantic relation.

• The KIPS Transactions:PartD
• /
• v.11D no.7 s.96
• /
• pp.1367-1374
• /
• 2004

For sharing XML data by many users, a way of concurrency and access control is required for isolating update actions such as inserting and deleting subtrees. Exisiting locking mechanisms as 2PL or MGL suffer low concurrency when applied to tree structures. In this paper, list data subtrees model is proposed based on the semantics expressed in DTD. In this model, tree updating actions such as inserting and deleting subtrees are considered only for the repetitive parts of XML trees. The proposed model guarantees that the result XML tree after applying a tree updating action is always valid, even when multiple users access the tree at the same time. Also, a new locking mechanism called list lock-ing protocol is proposed. The new locking protocol is expected to show better accessility with less number of locking objects compared to the Helmer's OO2PL model. Since update actions on a shared XML tree usually applied to the repetitive parts of the tree, the proposed model is expected to provide a useful way for efficient data sharing when combined with previous locking methods on terminal node data.

• Journal of KIISE:Computing Practices and Letters
• /
• v.15 no.4
• /
• pp.231-243
• /
• 2009

Many DSP systems are streaming applications in which streams of data constantly flow through a set of filters. Dataflow programming paradigm is one of effective methods for representing these streaming applications. Dataflow programming model explicitly exposes parallelisms within an application, which helps compiling of the application onto a multicore platform. We propose SPEX(Signal Processing Extension), a language extension to a standard imperative language based on the parameterized dataflow model. Parameterized dataflow model is a kind of dataflow model that can express a modest fashion of dynamism contrary to the synchronous dataflow that can represent only static dataflow. SPEX facilitates characterizing an application written in conventional imperative languages such C/C++ as a streaming application. SPEX is comprised of a few keywords augmented to the conventional C++ syntax for representing dataflow paradigm. SPEX also restricts the syntax and semantics of C++ in order to fit the program within a certain streaming programming category. In this paper, we focus on the capability of SPEX in representing streaming computations within filters and streaming communications among filters.

• Journal of KIISE:Databases
• /
• v.30 no.1
• /
• pp.1-13
• /
• 2003

In this paper, we present a content-dependent authorization mechanism for object-oriented database systems. So far, several models of authorization for object-oriented databases have been proposed, but most of these models do not support the authorization based on the database content. This paper shows how the traditional content-independent authorization model can be extended to provide the content-dependent authorization using predicates on the values of attributes of a class. The proposed model makes it possible to group objects that satisfy the specified conditions on the values of the objects and to grant a single authorization on those objects. This model supports the negative authorization and provides the concept of the strong and weak authorization to resolve conflicts between positive and negative authorizations. In addition, we address and resolve some of the problems that arise when the predicates are associated with the authorization. In particular, since the authorization operations of the traditional content- independent model become inadequate for our mode, we redefine the semantics of the authorization operations.

• Journal of the Korea Society for Simulation
• /
• v.27 no.3
• /
• pp.23-36
• /
• 2018

Discrete Event System Specification (DEVS) has been used for decades as it provides sound semantics for hierarchical modular specification of discrete event systems. Instead of the mathematical specification, the DEVS diagram, based on the structured DEVS formalism, has provided more intuitive and convenient representation of complex DEVS models. This paper proposes a clean room process for implementation and verification of a DEVS diagram model specification into a simulation software source code. Specifically, it underlies a sequence of transformation steps from conformance and integrity checking of a given diagram model, translation into a corresponding tabular model, and finally conversion to a simulation source code, with each step being inversely verifiable for traceability. A simple example helps developers to understand the proposed process with associated transformation methods; a case study shows that the proposed process is effective for and adaptable to practical simulation software development.

• International Journal of Computer Science & Network Security
• /
• v.21 no.5
• /
• pp.139-150
• /
• 2021

Object orientation has become the predominant paradigm for conceptual modeling (e.g., UML), where the notions of class and object form the primitive building blocks of thought. Classes act as templates for objects that have attributes and methods (actions). The modeled systems are not even necessarily software systems: They can be human and artificial systems of many different kinds (e.g., teaching and learning systems). The UML class diagram is described as a central component of model-driven software development. It is the most common diagram in object-oriented models and used to model the static design view of a system. Objects both carry data and execute actions. According to some authorities in modeling, a certain degree of difficulty exists in understanding the semantics of these notions in UML class diagrams. Some researchers claim class diagrams have limited use for conceptual analysis and that they are best used for logical design. Performing conceptual analysis should not concern the ways facts are grouped into structures. Whether a fact will end up in the design as an attribute is not a conceptual issue. UML leads to drilling down into physical design details (e.g., private/public attributes, encapsulated operations, and navigating direction of an association). This paper is a venture to further the understanding of object-orientated concepts as exemplified in UML with the aim of developing a broad comprehension of conceptual modeling fundamentals. Thinging machine (TM) modeling is a new modeling language employed in such an undertaking. TM modeling interlaces structure (components) and actionality where actions infiltrate the attributes as much as the classes. Although space limitations affect some aspects of the class diagram, the concluding assessment of this study reveals the class description is a kind of shorthand for a richer sematic TM construct.

• The Journal of Society for e-Business Studies
• /
• v.10 no.2
• /
• pp.21-41
• /
• 2005

An Enterprise Architecture (EA) Framework is a tool which supports implementation of the Enterprise architecture that is used to enhance the interoperability of the IT components. In this paper, we propose a framework named as ENAE (ENterprise Architecture Framework) which combines enterprise architecture unit (AU), reference model, and association relationship between domain model. Architecture Unit is defined as a minimum set of a business process and its associated components such as application system and technical components. An EA can be designed and implemented by the aggregating the related AUs including association relationship between Architecture Units. Because UML model has limitations to describe business domain semantics because it is designed for general purpose, we adapt the DSM (Domain Specific Modeling) concept. We describe association relationship between Architecture Units designed by Domain Specific Modeling through Topic Map. Session 2 describes related works about Enterprise Architecture frameworks, Domain Specific Modeling, and Topic Map, while Session 3 explains components of the ENAF. Finally Session 4 shows the case study for implementation of the new Framework called ENAF.

• Journal of Internet Computing and Services
• /
• v.8 no.6
• /
• pp.135-144
• /
• 2007

Feature models are widely used in domain engineering phase of software product lines development to model the common and variable concepts among products. From the feature model, the feature configurations are generated by selecting the features to be included in target product. The feature configuration represents the requirements for the specific product to be implemented. Although there are a lot of researches on how to build and use the feature models and feature configurations, the researches on the formal semantics and reasoning of them are rather inactive. This paper proposes the feature configuration verification approach based on JESS, java-based rule-base system. The Graph Product Line, a standard problem for evaluating the software product line technologies, is used throughout the paper to illustrate this approach. The approach in this paper has advantage of presenting the exact reason causing inconsistency in the feature configuration. In addition, this approach should be easily applied into other software product lines development environments because JESS system can be easily integrated with Java language.

• The Journal of Natural Sciences
• /
• v.8 no.1
• /
• pp.115-121
• /
• 1995

The Conventional database management system is not applicable because of their inadequate performance and difficulty of CAD database that is dependant to hierarchical structure and to repeat accesses of large data. For effective management and easy tool integration of CAD database, hierarchy Interface System(HIS) is designed and GROCO(Graph Representation fOr Complex Objects) Model is presented. Hierarchy Interface System which is composed of two subsystems of a configurator and a converter is designed for the interface between a conventional database management system and CAD tools. GROCO Model is a directed cyclic graph having five node-types for representing semantics and supports efficiently CAD database characters having a hierarchical structure of complex objects.