• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.67-74
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• 2004

Most of today's parallel numerical schemes use synchronous algorithms, where some processors that have finished their tasks earlier than others must wait at synchronization points for correct computation. Hence overall performance of the system is dependent upon the speed of the slowest processor. In this paper, we det·ise a synchronous/asynchronous hybrid algorithm to accelerate convergence of the solution for finding the dominant eigenpair of a large matrix, by reducing the idle times of faster processors using MPMD programming methodology.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.227-233
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• 2003

In paper, we present design and implementation of MPLS based VPN with QoS capabilities. We propose a design architecture of an edge router for MPLS based VPN with QoS capabilities in backbone network. We design functional blocks, interface specifications, detail routing and forwarding information based structure, and packet forwarding engine for the purpose of implementation of an edge router, We extend bgp-4 software for implementation differentiated service packet forwarding schemes in MPLS based VPN.

• ETRI Journal
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• v.35 no.6
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• pp.1144-1147
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• 2013

Dual-mode terminals (DMTs) equipped with cellular and WLAN interfaces have become popular in recent years. Users of DMTs can enjoy high-speed WLAN Internet access and wide area Internet access to cellular networks. However, a DMT may consume power inefficiently when discovering a WLAN with inherently limited service coverage. In this letter, we propose to use smart WLAN discovery (SWD) to minimize the power consumption required for WLAN discovery. To minimize the power consumption of a DMT, an SWD DMT activates its WLAN interface only when the DMT transfers data within the WLAN coverage area. The simulation results of SWD show an improved power-saving performance compared to previous WLAN discovery schemes.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.1
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• pp.8-13
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• 2006

In mobile ad hoc networks, most of on demand routing protocols such as DSR and AODV do not deal with traffic load during the route discovery procedure. To achieve load balancing in networks, many protocols have been proposed. However, existing load balancing schemes do not consider the remaining available buffer size of the interface queue, which still results in buffer overflows by congestion in a certain node which has the least available buffer size in the route. To solve this problem, we propose a load balancing protocol called Dynamic Congestion Aware Routing Protocol (DCAR) which monitors the remaining buffer length of all nodes in routes and excludes a certain congested node during the route discovery procedure. We also propose two buffer threshold values to select an optimal route selection metric between the traffic load and the minimum hop count. Through simulation study, we compare DCAR with other on demand routing protocols and show that the proposed protocol is more efficient when a network is heavily loaded.

• Journal of Communications and Networks
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• v.14 no.4
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• pp.410-417
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• 2012

One of the premier mechanisms used in extracting unobserved signals from observed mixtures in signal processing is employing a blind source separation (BSS) algorithm. Orthogonal frequency division multiplexing (OFDM) techniques are playing a prominent role in the sphere of multicarrier communication. A set of remedial solutions taken to mitigate deteriorative effects caused within the air interface of OFDM transmission with aid of BSS schemes is presented. Four energy functions are used in deriving the filter coefficients. Energy criterion functions to be optimized and the performance is justified. These functions together with iterative fixed point rule for receive signal are used in determining the filter coefficients. Time correlation properties of the channel are taken advantage for BSS. It is tried to remove colored noise and jamming components from themixture at the receiver. Themethod is tested in a slow fading channel with a receiver containing equal gain combining to treat the channel state information values. The importance is that, these are quite low computational complexity mechanisms.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.19-26
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• 2008

From numerical point of view on flow network system analyses, stagnation properties are not preserved along streamlines across geometric discontinuities. Hence, GJM and DTM using ghost cell and thermodynamic relations are developed to preserve the stagnation enthalpy for the boundaries, such as the interfaces between junction and branches and the interface between two pipes of different cross-sections in serial pipelines. Additionally, the resolving power and efficiencies of the 2nd order Godunov type FV schemes are investigated and estimated by the tracing of the total mechanical energy during calculating rapid transients. Among the approximate Riemann solvers, RoeM is more suitable with the proposed boundary treatments especially for junction than Roe's FDS because of its conservativeness of stagnation enthalpy across geometric discontinuities.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.19-26
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• 2008

From numerical point of view on flow network system analyses, stagnation properties are not preserved along streamlines across geometric discontinuities. Hence, GJM and DTM using ghost cell and thermodynamic relations are developed to preserve the stagnation enthalpy for the boundaries, such as the interfaces between junction and branches and the interface between two pipes of different cross-sections in serial pipelines. Additionally, the resolving power and efficiencies of the 2nd order Godunov type FV schemes are investigated and estimated by the tracing of the total mechanical energy during calculating rapid transients. Among the approximate Riemann solvers, RoeM is more suitable with the proposed boundary treatments especially for junction than Roe's FDS because of its conservativeness of stagnation enthalpy across geometric discontinuities.

• Journal of computational fluids engineering
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• v.20 no.1
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• pp.57-64
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• 2015

This paper describes a volume of fluid(VOF) method, mRHRIC for the simulation of free surface flows around ship hulls and provides its validation against benchmark test cases. The VOF method is developed on the basis of RHRIC method developed by Park et al. that uses high resolution differencing schemes to algebraically preserve both the sharpness of interface and the boundedness of volume fraction. A finite volume method is used to solve the governing equations, while the realizable ${\kappa}-{\varepsilon}$ model is used for turbulence closure. The present numerical results of the resistance performance tests for DTMB5415 and KCS hull forms show a good agreement with available experimental data and those of other free surface methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.241-245
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• 2003

In this paper, a microassembly system based on hybrid manipulation schemes is proposed and applied to the assembly of a photonic component. In order to achieve both high precision and dexterity in microassembly, we propose a hybrid microassembly system with sensory feedbacks of vision and force. This system consists of the distributed 6-DOF micromanipulation units, the stereo microscope, and haptic interface for the force feedback-based microassembly. A hybrid assembly method, which combines the vision-based microassembly and the scaled teleoperated microassembly with force feedback, is proposed. The feasibility of the proposed method is investigated via experimental studies for assembling micro opto-electrical components. Experimental results show that the hybrid microassembly system is feasible for applications to the assembly of photonic components in the commercial market with better flexibility and efficiency.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.499-502
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• 1999

This paper presents a PCI (Peripheral Component Interconnect) controller embedded in a multimedia processor, called FLOVA (FLOating point VLIW Architecture), targeting for 3D graphics applications. Fast I/O interfaces are essential for multimedia processors which usually handle large amount of multimedia data. Therefore, in FLOVA, PCI bus is adopted for I/O interface due to fast burst transaction. However, there are several problems in implementation and verification to use burst transaction of PCI. It is difficult to handle data transaction between two units which have two different operating frequency. FLOVA has more higher operating frequency about 100MHz than that of PCI local bus and it makes lower utilization of FLOVA bus. Also, traditional simulation is not sufficient for verification of PCI functionality. In this paper, we propose buffering schemes to implement the PCI controller with wide bandwidth and high bus utilization. Also, this paper shows how to verify the PCI controller using real PCI bus environments before its fabrication.