• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.899-912
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• 2000

PVM provides users with a single image of high performance parallel computing machine by collecting machines distributed over a network. Low communication overhead is essential to effectively run applications on PVM based platforms. In the original PVM, three times of memory copies are required for a PVM task to send a message to a remote task, which results in performance degradation. We propose a zero-copy model using global shared memory that can be accessed by PVM tasks, PVM daemon, and network interface card(NIC). In the scheme, a task packs data into global shared memory, and notify daemon that the data is ready to be sent, then daemon routes the data to a remote task to which it is sent with no virtual data copy overhead. Experimental result reveals that the message round trip time between two machines is reduced significantly in the proposed zero-copy scheme.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.3
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• pp.356-363
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• 2000

Java programming language is designed to run effectively on internet and distributed network environments. However, because it has a deficit to be executed by the interpreter method on each platform, to execute Java programs efficiently the code generation system which transforms Bytecode into SPARC code as target machine code must be developed. In this paper, we implement a code generation system which translates Bytecode into SPARC code using the retargetable code generating techniques. For the sake of code expander, we wrote a Bytecode table describing a rule of SPARC code generation from Bytecode, and implemented the information extractor transforming Bytecode to suitable form during expanding of source code from class file. The information extractor determines constant pool entry of each Bytecode instruction operand and then the code expander translates the Bytecode into SPARC code accoring to the Bytecode table. Also, the retargetable code generation system can be systematically reconfigured to generate code for a variety of distinct target computers.

• KIISE Transactions on Computing Practices
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• v.20 no.12
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• pp.623-631
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• 2014

Comparison of two representative deduplication file systems, LessFS and SDFS, shows that Lessfs is better in execution time and CPU utilization while SDFS is better in storage usage (around 1/8 less than general file systems). In this paper, a new system is proposed where the advantages of SDFS and Lessfs are combined. The new system uses multiple DFEs and one DSE to maintain the integrity and consistency of the data. An evaluation study to compare between Single DFE and Dual DFE indicates that the Dual DFE was better than the Single DFE. The Dual DFE reduced the CPU usage and provided fast deduplication time. This reveals that proposed system can be used to solve the problem of an increase in large data storage and power consumption.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.6
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• pp.371-377
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• 2007

In this paper, we propose the effective operating device in the container freight station by applying the RTLS (Real Time Location System) that provides information on the container's location in real time so that the performance of the port operating system can be improved. For this, we proposed the improved dual cycling method made with the new application of two types of container's location & yard tractor's location information. we applied the RTLS to the container freight station to send the container location data to the operating system in real time; we designed the data on the Yard Tractor's location to be received via the GPS receiver and then be sent to the operating system in real time via the CDMA module. According to the analysis and evaluation of the performance of the proposed method, up to 24% of performance improvement was shown compared with the existing methods, in aspect of evaluation of work time, work time deviation and performance. Therefore, we proved that the RTLS and the GPS receiver are essential elements for efficient port operation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.2
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• pp.118-126
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• 2004

Grid is a new Information Technology (IT) concept of "super Internet" for high-performance computing: worldwide collections of high-end resources such as supercomputers, storage, advanced instruments and immerse environments. The Grid is expected to bring together geographically and organizationally dispersed computational resources, such as CPUs, storage systems, communication systems, real-time data sources and instruments, and human collaborators. The term "the Grid" was coined in the mid1990s to denote a proposed distributed computing infrastructure for advanced science and engineering. The term computational Grids refers to infrastructures aimed at allowing users to access and/or aggregate potentially large numbers of powerful and sophisticated resources. More formally, Grids are defined as infrastructure allowing flexible, secure, and coordinated resource sharing among dynamic collections of individuals, institutions and resources referred to as virtual Organizations. GRID is an emerging IT as a kind of next generation Internet technology which will fit very well with agrometeorological services in the future. I believe that it would contribute to the resource sharing in agrometeorology by providing super computing power, virtual storage, and efficient data exchanges, especially for developing countries that are suffering from the lack of resources for their agmet services at national level. Thus, the establishment of CAgM-GRID based on existing RADMINSII is proposed as a part of FWIS of WMO.part of FWIS of WMO.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.307-318
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• 2003

In this paper, we design and construct a TMO object group that provides the guaranteed real-time services in the distributed object computing environments, and verify execution power of its model for the correct distributed real-time services. The TMO object group we suggested is based on TINA's object group concept. This model consists of TMO objects having real-time properties and some components that support the object management service and the real-time scheduling service in the TMO object group. Also TMO objects can be duplicated or non-duplicated on distributed systems. Our model can execute the guaranteed distributed real-time service on COTS middlewares without restricting the specially ORB or the of operating system. For achieving goals of our model. we defined the concepts of the TMO object and the structure of the TMO object group. Also we designed and implemented the functions and interactions of components in the object group. The TMO object group includes the Dynamic Binder object and the Scheduler object for supporting the object management service and the real-time scheduling service, respectively The Dynamic Binder object supports the dynamic binding service that selects the appropriate one out of the duplicated TMO objects for the clients'request. And the Scheduler object supports the real-time scheduling service that determines the priority of tasks executed by an arbitrary TMO object for the clients'service requests. And then, in order to verify the executions of our model, we implemented the Dynamic Binder object and the Scheduler object adopting the binding priority algorithm for the dynamic binding service and the EDF algorithm for the real-time scheduling service from extending the existing known algorithms. Finally, from the numerical analyzed results we are shown, we verified whether our TMO object group model could support dynamic binding service for duplicated or non-duplicated TMO objects, also real-time scheduling service for an arbitrary TMO object requested from clients.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.2
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• pp.191-204
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• 2003

In the home gateway environment, several characteristics for the user authentication mechanism should be reflected separately from the existing distributed service environment. First, the platform of a home gateway is a component based system that its services are installed dynamically. Second, the convenience that user can use several services by authentication of once should be offered. Finally, the system resources of a home gateway are restricted. However, a user authentication mechanism that reflected these characteristics is not shown at the user admin service specification of the OSGi service platform.(OSGi is the representative standardization organization of hone gateway.) Also, there is no existing authentication protocol that satisfies these qualities at the same time. In this paper, we propose a new user authentication mechanism considering those characteristics for the home gateway environment. We also design and implement an independent authentication service bundle based on the OSGi service platform so that it can perform user authentication operations for each bundle service. We supplement and extend the Kerberos Protocol that can apply.

• Journal of Korea Spatial Information System Society
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• v.1 no.2 s.2
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• pp.33-46
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• 1999

In distributed computing platforms like CORBA, wrappers are used to integrate heterogeneous systems or databases. A spatial data provider is one of the wrappers because it provides clients with uniform access interfaces to diverse data sources. The individual implementation of spatial data providers for each of different data sources is not efficient because of redundant coding of the wrapper modules. This paper presents a new architecture of the spatial data provider which consists of two layered objects : independent wrapper components and dependent wrapper components. Independent wrapper components would be reused for implementing a new data provider for a new data source, which dependent wrapper components should be newly coded for every data source. This paper furthermore discussed the issues of implementing the representation of query results in the middleware. There are two methods of keeping query results in the middleware. One is to keep query results as non-CORBA objects and the other is to transform query results into CORBA objects. The evaluation of the above two methods shows that the cost of making CORBA objects is very expensive.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1041-1051
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• 2012

Attack on Cloud Computing, an intensive service solution using network infrastructure recently released, generates service breakdown or intrusive incidents incapacitating developmental platforms, web-based software, or resource services. Therefore, it is needed to conduct research on security for the operational information of three kinds of services (3S': laaS, PaaS, SaaS) supported by the Cloud Computing system and also generated data from the illegal attack on service blocking. This paper aims to build a system providing optimal services as a 4-stage defensive method through the test on the attack and defense of Cloud Computing services. It is a defense policy that conducts 4-stage, orderly and phased access control as follows: controlling the initial access to the network, controlling virtualization services, classifying services for support, and selecting multiple routes. By dispersing the attacks and also monitoring and analyzing to control the access by stage, this study performs defense policy realization and analysis and tests defenses by the types of attack. The research findings will be provided as practical foundational data to realize Cloud Computing service-based defense policy.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.651-656
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• 2003

Emerging technologies, such as multimedia and mobile computing, require that middleware platforms can support high adaptability in order to provide more flexible services in heterogeneous environments. To support high quality of service in distributed wired/wireless environments, it will be necessary for applications and middleware to be aware of changes in users requirements as well as environmental conditions, also to be able to adapt their behaviour as such changes. According to the needs of adaptability supporting in middleware, we structure a component-based, mobile agents framework in base level and meta level by using reflection. We propose concepts of meta agents and meta-service agents that are able to reflect changes made by mobile agents to the system. At the meta level of our framework, meta agents monitor execution of mobile agents and it is possible to provide dynamic adaptation of users requirements, deployment of application services and service customization with meta agents and meta-service agents.