• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.449-456
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• 1999

본 논문은 C++에 분산 객체 프로그래밍 기능을 추가한 D++ 언어를 제안한다. 대등관계 복제객체 모델을 지원하는 D++는 분산 클래스의 정의, 멤버 함수의 일치성 제어 정의 기능, 그리고 영구 객체 이름에 기반한 분산 객체를 정의할 수 있는 언어 구조를 제공한다. D++ 프로그램에서 새로이 생성되는 분산 객체는 생성 시에 제공되는 객체의 영구 이름과 동일한 영구 이름을 갖는 분산 객체가 존재할 경우 해당 객체들과 복제 관계를 유지함으로써 정보를 공유한다. 각 복제 객체들은 서로 간에 대등한 관계를 가지며, 멤버 함수 정의 시에 기술되는 특성에 따라 일치성이 유지된다. 이 같은 D++의 분산 객체 모델은 실시간 그룹웨어의 기본 요구 사항인 분산 환경에서의 정보 공유 및 사건 공지 기능을 자연스럽게 해결해 주기 때문에 실시간 그룹웨어의 개발을 효율적으로 지원할 수 있을 것으로 기대한다. Abstract This paper proposes D++ programming language that is an extension of C++ for distributed object oriented programming. The D++, which supports peer-to-peer object model, provides new language constructs for the definition of distributed classes, the definition of the consistency control of the member function and the definition of distributed object variables with the persistent name. In D++, when the persistent name of a newly created distributed object is same as that of an existing distributed object, the new distributed object replicates object state of the existing distributed object and thus they share the object state. The replicas have peer relation and the consistency among them is maintained according to the characteristic described on the definition of designated member functions. It is expected that D++ language increases efficiency in development of real-time groupware because the distributed object model of D++ naturally supports the information sharing and event notification that are the basic functions required when building real-time groupware.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.440-448
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• 1999

본 논문은 객체지향형 분산처리 환경 하에서 오디오나 비디오 등과 같은 실시간(real-time) 스트림(stream) 데이타를 처리하는 데 필요한 소프트웨어 기반구조를 설계하고 구현한 내용을 기술한다. 본 논문에서 제시한 DAViS(Distributed Object Framework supporting Audio/Video Streaming)는, 오디오/비디오 데이타의 처리와 관련된 여러 소프트웨어 구성요소들을 분산객체로 추상화하고, 그 객체들간의 제어정보 교환경로와 오디오/비디오 데이타 전송경로를 서로 분리하여 처리한다. 분산응용프로그램 작성자는 DAViS에서 제공하는 서비스들을 이용하여, 기존의 분산프로그래밍 환경이 제공하는 것과 동일한 수준에서 오디오/비디오 데이타에 대한 처리를 표현할 수 있다. DAViS는, 새로운 형식의 오디오/비디오 데이타를 처리하는 부분을 손쉽게 통합하고, 하부 네트워크의 전송기술이나 컴퓨터시스템 관련 기술의 진보를 신속하고 자연스럽게 수용할 수 있도록 하는 유연한 구조를 가지고 있다. Abstract This paper describes the design and implementation of software framework which supports the processing of real-time stream data like audio and video in distributed object-oriented computing environment. DAViS(Distributed Object Framework supporting Audio/Video Streaming), proposed in this paper, abstracts software components concerning the processing of audio/video data as distributed objects and separates the transmission path of data between them from that of control information. Based on DAViS, distributed applications can be written in the same abstract level as is provided by the existing distributed environment in handling audio/video data. DAViS has a flexible internal structure enough to easily incorporate new types of audio/video data and to rapidly accommodate the progress of underlying network and computer system technology with very little modifications.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.602-613
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• 2001

Recently, the computing has developing in distributed object computing environment for supporting a programming paradigm of distributed application requiring interoperability between heterogeneous clients and servers. It involves the complex networking and the object-oriented technologies for various multimedia application service. In this paper, we construct the real-time object group platform for solving the difficulties of managements of distributed objects and the real-time constraints by requiring for real-time service supporting of applications in distributed computing environment. The existing researches are being tried to only improving the performance of systems by using real-time CORBA itself, or modifying the part of CORBA compliance. Hence, we design a new model of real-time object group platform that can support the real-time requirement without modifying the ORB. The structure of our real-time object group analyzed and defined the requirement about object management and real-time application service sides. And the role of the components of real-time object group is divided into 2 classes for reducing the side effect of interoperability between management and service. Also, we considered how to transparently express the parameters of real-time properties for clients and developers of server's service objects. If the expression of real-time parameters is transparent, then the developer can easily extend the real-time parameters simply and flexibly. Therefore, in this paper we defined the role of components of platform and described functions of each component and designed and then implemented the real-time object group platform. Finally, we showed the execution procedures of implemented our platform for verifying the functionality.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.2
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• pp.1-9
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• 2002

The use of Object-Oriented Distributed Programming(OODP) environment such as DCOM, DSOM, Java RMI, CORBA to implement distributed applications is becoming increasingly popular. However, absence of a fault-tolerance feature in these middleware platforms complicates the design and implementation of reliable distributed object-based applications, although they greatly enhance the quality and reusability of the distributed object-based applications. In this paper, we propose a fault-tolerant programming environment based on RMI, namely Evergreen, for the reliable distributed computing with checkpoints and rollback-recovery mechanism. Based on a series of experiments, we evaluate the performance of Evergreen and find its possibility of extension to fully support our optimal design goal.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.6
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• pp.555-568
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• 2000

The World Wide Web has become the largest virtual system that is almost universal in scope. In recent research, it has become effective to utilize idle hosts existing in the World Wide Web for running applications that require a substantial amount of computation. This novel computing paradigm has been referred to as the advent of global computing. In this paper, we implement and propose a mobile object-based global computing framework called Tiger, whose primary goal is to present novel object-oriented programming libraries that support distribution, dispatching, migration of objects and concurrency among computational activities. The programming libraries provide programmers with access, location and migration transparency for distributed and mobile objects. Tiger's second goal is to provide a system supporting requisites for a global computing environment - scalability, resource and location management. The Tiger system and the programming libraries provided allow a programmer to easily develop an objectoriented parallel and distributed application using globally extended computing resources. We also present the improvement in performance gained by conducting the experiment with highly intensive computations such as parallel fractal image processing and genetic-neuro-fuzzy algorithms.

• Journal of KIISE:Software and Applications
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• v.31 no.6
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• pp.728-740
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• 2004

The increasing complexity and shorter life cycle of software have made it necessary to reuse software. Object-oriented development had not provided extensive reuse and computing infrastructures are evolving from mainframe to distributed environments. However, components provide more advanced means of structuring, describing and developing system, because they are more coarse-grained and have more domain-specific aspects than objects. And they are also suited for distributed environment due to their reusability and granularity. In this paper, we present a process including the static metrics and guidelines that can be applied to transform object-oriented systems into component-based systems. Our process consists of two parts: First, basic components are created based upon composition and inheritance relationships between classes. Second, intermediate system is refined into component-based system with the static metrics and guidelines we propose.

• Journal of Internet Computing and Services
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• v.5 no.3
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• pp.87-98
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• 2004

There are several types of distributed subscribers network using Asymmetric Digital Subscriber Line (ADSL), Very high-bit rate Digital Subscriber Line (VDSL), and Data Over Cable Service Interface Specifications (DOCSIS), The efficient and concentrated network management of those several distributed subscribers networks and resources require the general information model of network, which has abstract and conceptional managed objects independent of type of network and its equipment to manage the integrated subscriber network, This paper presents the general Internet subscribers network modeling framework using RM-ODP (Reference Model Open Distributed Processing) to manage that network In the form of integrated hierarchy, This paper adopts the object-oriented development methodology with UML (Unified Modeling Language) and designs and implements the HFC network of DOCSIS as an example of the subscriber network.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.120-134
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• 2000

In this paper we present a Distributed Object oriented Virtual computing Environment, called DOVE which consists of autonomous distributed objects interacting with one another via method invocations based on a distributed object model. DOVE appears to a user logically as a single virtual computer for a set of heterogeneous hosts connected by a network as if objects in remote site reside in one virtual computer. By supporting efficient parallelism, heterogeneity, group communication, single global name service and fault-tolerance, it provides a transparent and easy-to-use programming environment for parallel applications. Efficient parallelism is supported by diverse remote method invocation, multiple method invocation for object group, multi-threaded architecture and synchronization schemes. Heterogeneity is achieved by automatic data arshalling and unmarshalling, and an easy-to-use and transparent programming environment is provided by stub and skeleton objects generated by DOVE IDL compiler, object life control and naming service of object manager. Autonomy of distributed objects, multi-layered architecture and decentralized approaches in hierarchical naming service and object management make DOVE more extensible and scalable. Also,fault tolerance is provided by fault detection in object using a timeout mechanism, and fault notification using asynchronous exception handling methods

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.553-555
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• 2001

본 논문에서는 분산 가상 환경을 기반으로 한 원격교육시스템을 제안한다. 기존에 제안되었던 대부분의 원격교육시스템 들은 클라이언트/서버 구조를 택함으로써 시스템의 확장성과 속도에 많은 단점을 가지고 있었다. 이러한 단점을 보완하고자 본 논문에서는 분산 객체 모델을 기반으로 peer-to-peer 구조를 가지는 새로운 원격교육시스템을 소개한다. DOVE(Distributed Object-oriented virtual computing environment)라는 분산 가상 환경 상에서 설계된 본 시스템은 peer-to-peer 구조를 가짐으로써 기존 시스템들의 확장성 문제를 해결했을 뿐만 아니라 DOVE의 가장 큰 장점 중에 하나인 객체 그룹(Object Group)의 개념을 도입하여 객체간에 멀티캐스트를 기반으로 한 상호작용을 가능케 함으로써 속도와 부하 문제도 해결하였다.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.69-88
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• 2000

One of the most important factors on the performance of the distributed systems is the effective distribution of the software components, There have been a lot of researches on partitioning and allocating the task-based system, while the studies on the allocating the objects of the object-oriented system into the distributed object environments are very little relatively. In this paper. we defines the graph model for partitioning the existing C++ application and allocating the C++ objects into CORBA-base distributed system, In addition, we propose a distributed object allocation algorithm based on this graph model. The performance of distributed systems is determined by the concurrency between objects, the load balance among the processors and the communication cost on the networks. To search for the solutions optimizing the above three factors simultaneously, the object allocation algorithm of this paper is based on the Niched Pareto Genetic Algorithm (NPGA). We performed the experiment on the typical C++ application and CORBA system to prove the effectiveness of our graph model and our object allocation algorithm.