• Journal of Korea Multimedia Society
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• v.12 no.3
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• pp.419-426
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• 2009

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. The WiMedia D-MAC fundamentally removes the problems of the centralized MAC revealed at IEEE 802.15.3 MAC, by adopting a distributed architecture. However, there is no completely distributed method for allocating fair data rates to all traffic streams by considering each stream's QoS parameter. In this paper, a novel fair distributed QoS admission control method is proposed. The proposed method is a fair, adaptive QoS provisioning method, by allocating time slots to devices according to the current traffic load condition, through executing only a proposed single satisfaction of QoS (SoQ) algorithm at each device.

• Journal of Korean Society on Water Environment
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• v.36 no.5
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• pp.373-384
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• 2020

Hydrological models are based on a combination of parameters that describe the hydrological characteristics and processes within a watershed. For this reason, the model performance and accuracy are highly dependent on the parameters. However, model uncertainties caused by parameters with stochastic characteristics need to be considered. As a follow-up to the study conducted by Choi et al (2020), who developed a relatively simple semi-distributed hydrological model, we propose a tool to estimate the posterior distribution of model parameters using the Metropolis-Hastings algorithm, a type of Markov-Chain Monte Carlo technique, and analyze the uncertainty of model parameters and simulated stream flow. In addition, the uncertainty caused by the parameters of each version is investigated using the lumped and semi-distributed versions of the applied model to the Hapcheon Dam watershed. The results suggest that the uncertainty of the semi-distributed model parameters was relatively higher than that of the lumped model parameters because the spatial variability of input data such as geomorphological and hydrometeorological parameters was inherent to the posterior distribution of the semi-distributed model parameters. Meanwhile, no significant difference existed between the two models in terms of uncertainty of the simulation outputs. The statistical goodness of fit of the simulated stream flows against the observed stream flows showed satisfactory reliability in both the semi-distributed and the lumped models, but the seasonality of the stream flow was reproduced relatively better by the distributed model.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1433-1442
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• 1996

Data distribution of SPMD(Single Program Multiple Data) pattern is one of main features of HPF (High Performance Fortran). This paper describes design is sues for such data distribution and its efficient execution model on TICOM IV computer, named SPAX(Scalable Parallel Architecture computer based on X-bar network). SPAX has a hierarchical clustering structure that uses distributed shared memory(DSM). In such memory structure, it cannot make a full system utilization to apply unanimously either SMDD(shared Memory Data Distribution) or DMDD(Distributed Memory Data Distribution). Here we propose another data distribution model, called DSMDD(Distributed Shared Memory Data Distribution), a data distribution model based on hierarchical masters-slaves scheme. In this model, a remote master and slaves are designated in each node, shared address scheme is used within a node and message passing scheme between nodes. In our simulation, assuming a node size in which system performance degradation is minimized,DSMDD is more effective than SMDD and DMDD. Especially,the larger number of logical processors and the less data dependency between distributed data,the better performace is obtained.

• The Transactions of the Korea Information Processing Society
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• v.4 no.11
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• pp.2721-2731
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• 1997

Distributed programming can be greatly simplified by language support for distributed communication. Many web-browsers now offer some form of active objects and the number and types of them are growing daily in interesting and innovative ways. Java applets are well known as one kind of active object related to web-browser. This paper focuses in distributed active objects which is one kind of active objects that can communicate with other active objects located in different machines across the Internet. Java RMI and CORBA IDL are two major programming environments for distributed active objects which are non compatible with each other. To make discussion concrete, we introduce a single application as implemented on two environments : the HORM, adopting RMI mechanism, and the OrbixWeb2.0.1, adopting CORBA specification, respectively. Binding, inheritance, polymorphism, object passing and callbacks across the machine boundary in distributed programming environments are issued. The results show that some differences in the implementation of distributed active objects can have a significant impact on how distributed applications are structured. The comparison between two implementations on the programming environments will be the basis for building the translation system between HORB to OrbixWeb and vice versa.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.919-943
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• 2019

Distributed ledger technology, which is attracting attention as an emerging technology related to the 4th Industrial Revolution, is implemented as an open source based distributed ledger technology system and widely used for development with various applications (or services), but the security functions provided by the distributed general ledger system are very insufficient. This paper proposes security enhancements for distributed ledger technology systems based on open source. To do so, potential security threats that may occur under running an open source based distributed ledger technology systems are identified and security functional requirements against the security threats identified are provided by analyzing legislation and security certification criteria (ISMS-P). In addition, it proposes a method to implement the security functions required for an open source based distributed ledger technology systems through analysis of security functional components of Common Criteria (CC), an international standard.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.77-85
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• 2020

In this paper, We studied the operation of distributed ledger technology used as a core technology for smart contracts and the components of distributed ledger technology. As a solution applying the entity of distributed ledger technology to NoE, we proposed the protocol of the distributed ledger technology using the thing user social group management function of NoE protocols being standardized in ISO/IEC JTC1 SC6. The management function of things user social group in NoE provides stable protocol functions and data transmission management, and provides group management functions such as member discovery function and data transmission channel management function. It is expected to be useful for member management functions of distributed ledger nodes by providing a service that apply the component of distributed ledger technology. We intend to actively reflect this technology in the future network functions of ISO/IEC JTC1 SC6, which is undergoing standardization.

• Proceedings of the CALSEC Conference
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• 1998.10b
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• pp.375-389
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• 1998

o Projects/Subprojects/Tasks Distributed over Teams, Departments, Enterprises and the Globe o Virtual Teaming/Enterprises o Limitations/Barriers on Distributed Work - Geographical - Communication(omitted)

• 전기의세계
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• v.19 no.2
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• pp.21-23
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• 1970

Necessary conditions of optimal distributed parameter control systems, Hamiltons coanonical equations, welerstress condition, transversality condition and boundary condition are obtained, when the control function is constrained and the performance index takes on the general form. Also it is concluded that the lumped parameter system is the special case of the distributed parameter system.

• Honam Mathematical Journal
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• v.26 no.4
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• pp.423-439
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• 2004

We are concerned with the robust control problem for the Keller-Segel equations with the distributed control and disturbance. We consider the present problem as a differential game finding the best control which takes into account the worst disturbance. We prove the existence of solutions and the optimality conditions to a corresponding problem.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1100-1107
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• 2016