• Journal of the Korea Society of Computer and Information
• /
• v.21 no.1
• /
• pp.65-72
• /
• 2016

Network virtualization is an emerging technology for solving the rigidity of the physical network infrastructure. The innovative technique virtualizes all resources in the network, including the network links and nodes, and provides a number of virtual networks on a single network infrastructure. In order to realize a virtual network, a thorough and complete monitoring of all resources in the network should be performed firstly. OpenFlow is an open source stack for network virtualization. However, it is impossible to apply OpenFlow to AP-based legacy wireless LAN environment because OpenFlow targets ethernet-based LAN environment. In this paper, we implement an adaptor-styled virtual switch for AP-based wireless LAN through customizing the Open vSwitch which is a virtual switch of OpenFlow. The evaluation test results show that the implemented OpenFlow stack operates successfully. The implemented OpenFlow stack can now be plugged immediately in existing AP-based wireless LAN environment and plays network resource monitoring. In the future, we can develop wireless LAN virtualization applications on the wireless OpenFlow stack.

• Proceedings of the Korean Information Science Society Conference
• /
• 2012.06d
• /
• pp.418-420
• /
• 2012

정보화 사회로 발전하고 네트워크가 큰 폭으로 발전함에 따라 사회에 대한 네트워크의 의존도가 커져 가고 있다. 그러나 네트워크가 발전할수록 미래의 다양한 사용자 요구사항 및 새로운 네트워크의 한계성이 나타나고 있다. 이러한 문제를 해결하기 위한 방안 중 하나로 OpenFlow기법이 제안되었다. 본 논문에서는 이러한 OpenFlow기반의 네트워크를 관리하기 위해 VN Manager(Virtual Network Manager)와 이를 활용한 경로 관리 프로그램을 구현하였다. 또한 경로 생성시 QoS를 보장하기 위해 Admission Control이 가능하도록 하였다.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2016.07a
• /
• pp.59-62
• /
• 2016

본 논문에서는 실종자 데이터베이스에 등록된 실종자에 대한 색인으로 텍스트 기반의 통제 색인만을 사용할 때 발생하는 문제점에 대한 해결책을 다룬다. 기존 실종자를 등록할 때 함께 등록하게 되는 실종자에 대한 이미지는 정형화 할 수 없어 실종자 조회에 사용될 수 없었다. 이러한 문제점을 해결하고자 OpenCV와 TensorFlow 를 이용하여 영상의 유사도를 추출함으로써 실종자의 이미지를 정형화시켜 유의미한 정보로 변경하여 사용하고자 하는 방법을 제안한다.

• 전기의세계
• /
• v.23 no.1
• /
• pp.61-68
• /
• 1974

This paper attempts to develop the algorithms and computer program for load flow solution and faults analysis of large power system by small digital computer. The Conventional methods for load flow solution and fault analysis of large power system require too much amount of computer memory space and computing time. Therefore, this paper describes the methad for reducing the computer memory space and computing time as follows. (1) Load Flow Solution; This method is to store each primitive impedance of lines along with a list of bus numbers corresponding to the both terminals of lines, and to store only nonzero element of bus admittance matrix. (2) Faults Analysis: This method is to partition a large power system into several groups of subsystems, form individual bus impedance matrix, store them in the storage, and assemble the only required portion of them to original total system by algorithm.

• Journal of Information Processing Systems
• /
• v.8 no.4
• /
• pp.603-620
• /
• 2012

Proxy Mobile IPv6 (PMIPv6) is a network-based mobility support protocol and it does not require Mobile Nodes (MNs) to be involved in the mobility support signaling. In the case when multiple interfaces are active in an MN simultaneously, each data flow can be dynamically allocated to and redirected between different access networks to adapt to the dynamically changing network status and to balance the workload. Such a flow redistribution control is called "flow mobility". In the existing PMIPv6-based flow mobility support, although the MN's logical interface can solve the well-known problems of flow mobility in a heterogeneous network, some missing procedures, such as an MN-derived flow handover, make PMIPv6-based flow mobility incomplete. In this paper, an enhanced flow mobility support is proposed for actualizing the flow mobility support in PMIPv6. The proposed scheme is also based on the MN's logical interface, which hides the physical interfaces from the network layer and above. As new functional modules, the flow interface manager is placed at the MN's logical interface and the flow binding manager in the Local Mobility Anchor (LMA) is paired with the MN's flow interface manager. They manage the flow bindings, and select the proper access technology to send packets. In this paper, we provide the complete flow mobility procedures which begin with the following three different triggering cases: the MN's new connection/disconnection, the LMA's decision, and the MN's request. Simulation using the ns-3 network simulator is performed to verify the proposed procedures and we show the network throughput variation caused by the network offload using the proposed procedures.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.6
• /
• pp.665-671
• /
• 2007

The purpose of this study is to find out a flow characteristics required by the design of a computer case and to provide information about the preliminary data of cooling efficiency of CPU and a flow inside of a case. We examined a flow characteristic-suction a tracing particle occurred from a surge tand installed at an inlet into a computer case and moving it to a exit duct-experimentally by using PIV. The experimental device was consists of a fan inflowing and discharging the air into the computer case and a slot installed with a CPU cooling ran add-on, and analyzed the data of Re-stress distribution, velocity distribution, and kinetic energy distribution. This research will make a great contribution to improvement of the efficiency and performance of notebook, workstation, server, and all the design of electronic devices using large scale integrated(LSI) as well as usual computers.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.17 no.3
• /
• pp.238-248
• /
• 1988

The flow pattern inside the power condenser is generally known to be very complicated due to the phase change and turbulence effects as well as the effect of condenser geometry. In the present study, the flow pattern inside the power condenser was numerically simulated with a personal computer. The widely known CHAMPION 2/E/FIX(Concentration, Heat and Momentum Program Instruction Outfit, 2D/Elliptic/Fixed grid) computer code was modified for this purpose. The flow was asssumed to be two-dimensional and steady-state, and the tube bank was considered to be homogeneous porous medium. Simple turbulent diffusion coefficients based on the appropriate experiments were obtained for the computation. Through this analytical approach, the flow pattern could be predicted fairly well. The computational results also show that the location of the air vent plays an important key role in determining the efficiency of the condenser.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.330-333
• /
• 2009

This paper proposes a method to estimate the flow speed of pedestrians in surveillance videos. In the proposed method, the average moving speed of pedestrians is measured by estimating the size of real-world motion from the observed motion vectors. For this purpose, pixel-to-meter conversion factors are calculated from camera geometry. Also, the height information, which is missing because of camera projection, is predicted statistically from simulation experiments. Compared to the previous works for flow speed estimation, our method can be applied to various camera views because it separates scene parameters explicitly. Experiments are performed on both simulation image sequences and real video. In the experiments on simulation videos, the proposed method estimated the flow speed with average error of about 0.1m/s. The proposed method also showed a promising result for the real video.

• Proceedings of the KIEE Conference
• /
• 1998.11b
• /
• pp.666-668
• /
• 1998

In this paper we illustrate the design of a node label data flow machine based on self-timed paradigm. Data flow machines differ from most other parallel architectures, they are based on the concept of the data-driven computation model instead of the program store computation model. Since the data-driven computation model provides the excution of instructions asynchronously, it is natural to implement a data flow machine using self timed circuits.

• Proceedings of the KOSOMBE Conference
• /
• v.1996 no.05
• /
• pp.73-76
• /
• 1996

Computer simulation and magnetic resonance angiograms(MRAs) are used to understand for flow patterns in the carotid arterial bifurcation. Steady momentum equation is solved by the finite volume method. A Phantom of the carotid artery made of bioacrylic material is used for MRA observation. Flow Patterns are observed by using MRA for flow in the phantom of an automatic closed-type circulatory system filled with sugar 4 w% solution. For numerical analysis the idealized geometric shape of the carotid artery is constructed to portray the phantom. Results of numerical analysis are compared with those of MRA. The flow patterns of the phantom on MRA are almost identical to those of the computer simulation.