• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.741-743
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• 2000

In this paper the relationship between the pressing force applied to rotors and the characteristics of ultrasonic motor are discussed. The characteristics of ultrasonic motor using a piezoelectric vibrator were systematically studied. And these were applied to the construction of a card forwarding device. The principle of ultrasonic motor is to use an elliptical motion generated on the side of the vibrator, and the elliptical motion of the ultrasonic motor was obtained by complex oscillation of $L_1-B_4$ mode. As the experimental results. the forwarding speed of the card increased linearly as the pressing force applied to rotors increased. The forwarding speed of the card was 16.0 cm/s when the pressing force applied to rotors was 1 N. The forwarding force of the card increased linearly as the pressing force applied to rotors increased. The forwarding force of the card was 398 mN when the pressing force applied to rotors was 1 N. Therefore, this ultrasonic motor can be expected to be used for card-forwarding device and so on.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.846-864
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• 2017

Software Defined Network (SDN) realizes management and control over the underlying forwarding device, along with acquisition and analysis of network topology and flow characters through south bridge protocol. Data path Identification (DPID) is the unique identity for managing the underlying device, so forged DPID can be used to attack the link of underlying forwarding devices, as well as carry out DoS over the upper-level controller. This paper proposes a dynamic defense method based on Client-Puzzle model, in which the controller achieves dynamic management over requests from forwarding devices through generating questions with multi-level difficulty. This method can rapidly reduce network load, and at the same time separate attack flow from legal flow, enabling the controller to provide continuous service for legal visit. We conduct experiments on open-source SDN controllers like Fluid and Ryu, the result of which verifies feasibility of this defense method. The experimental result also shows that when cost of controller and forwarding device increases by about 2%-5%, the cost of attacker's CPU increases by near 90%, which greatly raises the attack difficulty for attackers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.414-417
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• 2001

Recently, developments of device using characteristics of ceramics as a new technical material is in progress. While doing so, Ultrasonic motor which is a part of research & flat-type $L_1-B_8$ mode Ultrasonic motor and measured the operation characteristics of its. The size of USM is 80*20*1.5[$mm{^1}$](length*width*thickness) and is constructed with stator by piezo-ceramics and stainless elastic body and rotator by bearings. As results of experiments, the fastest speed of revolution($\upsilon$), the maximum torque(T) and the efficiency($\eta$) were 37.5[cm/sec], 5.0[mN$\cdot$M] and 1.17[%] respectively when 27.9[kHz], 150[gf], 50[V] were applied. SO, we think this flat-type $L{_1}-B{_8}$ mode Ultrasonic motor is able to be used for applications in forwarding device of a paper or electric card so on. Key Words: Flat=type $L{_1}-B{_8}$ mode Ultrasonic Motors, Piezoelectric ceramics, forwarding device.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1440-1442
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• 2016

As long term evolution (LTE) is the most widely deployed broadband communication technology so far, efforts are being made to develop LTE-based mission critical public safety (PS) communication systems. In this paper, we propose a device-to-device (D2D) discovery-based radio resource acquisition scheme to support the LTE D2D communication to PS systems and the realization of resource forwarding for user equipments in emergency area.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.809-816
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• 2023

The purpose of this study is to implement a device using the Raspberry Pi that can transmit and supervise data between devices and servers using the oneM2M standard platform, Mobius. Operating under the same concept as a Gateway or Router, this device performs the role of forwarding packets sent from end nodes to other networks. Theoretical functionality has been achieved to concurrently connect and supervise up to 65536 devices. The communication methods for end nodes connected to the Gateway include ZigBee and WiFi, and for long-distance communication, tests were conducted using LoRa modules.

• IE interfaces
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• v.14 no.3
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• pp.263-271
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• 2001

MPLS LER is located at the boundary of MPLS domain as an ingress or an egress router and plays a role in connecting with the existing Internet. Among the components of the MPLS LER, forwarding engine(FE) is a key device which assigns a label to an IP packet by analyzing the destination address of its header in order to enter the MPLS domain, or restructures the cells from MPLS domain into IP packet by reversely processing. In this paper, we investigate the design of FE by analyzing the traffic performance of its components and estimate the IP packet processing capacity of a FE using queueing model and simulation. It is found that the maximum IP packet processing capacity of the Forwarding Engine is about 150,000 packets/sec.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.414-417
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• 2001

Recently, developments of device using characteristics of ceramics as a new technical material is in progress. While doing so, Ultrasonic motor which is a part of research & development of piezo-actuator by piezo-effects is being used in the various applications. So, we fabricated a flat-type $L_{1}-B_{8}$ mode Ultrasonic motor and measured the operation characteristics of its. The size of USM is 80*20*1.5[$mm^{3}$](length*width*thickness) and is constructed with stator by piezo-ceramics and stainless elastic body and rotator by bearings. As results of experiments, the fastest speed of revolution(v), the maximum torque(T) and the efficiency( $\eta$ ) were 37.5[cm/sec], 5.0[ $mN{\cdot}m$ ] and 1.17[%] respectively when 27.9[kHz], 150[gf], 50[V] were applied. So, we think this $flat-type_{1}-B_{8}$ mode Ultrasonic motor is able to be used for applications in forwarding device of a paper or electric card and so on.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.215-217
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• 2004

In wireless sensor networks, fair allocation of bandwidth among different nodes is one of the critical problems that effects the serviceability of the entire system. Fair bandwidth allocation mechanisms, like fair queuing, usually need to maintain state, manage buffers, and perform packet scheduling on a per flow basis, and this complexity may prevent them from being cost-effectively implemented and widely deployed. It is a very important and difficult technical issue to provide packet scheduling architecture for fairness in wireless sensor networks. In this paper, we propose an packet scheduling architecture for sensor node, called FISN (Fairness Improvement Sensor Network), that significantly reduces this implementation complexity yet still achieves approximately fair bandwidth allocations. Sensor node for sensing estimate the incoming rate of each sensor device and insert a label into each transmission packet header based on this estimate. Sensor node for forwarding maintain no per flow state; they use FIFO packet scheduling augmented by a probabilistic dropping algorithm that uses the packet labels and an estimate of the aggregate traffic at the gathering node. We present the detailed design, implementation, and evaluation of FISN using simulation. We discuss the fairness improvement and practical engineering challenges of implementing FISN in an experimental sensor network test bed based on ns-2.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.292-297
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• 2002

In this paper, a flat-type $L_{-}$-$B_{8}$ mode Ultrasonic Motor[USM] having the size of 80 x 20 x ${1.5}mm^3$($l{\times}\omega{\times}t$) was designed and fabricated to examine the characteristics of an ultrasonic vibration. We used ANSYS simulation program based on FEM to get the optimum design of this USM. As results of experiment, the fastest speed of revolution(v), the maximum torque(T) and the efficiency(n) were 37.5cm/s, 5.0 mN.m and 1.17% when 27.9KHz, 150N, 50V were applied respectively. And this flat-type $L_{-}$-$B_{8}$ mode USM could be controlled the speed of rotor revolution by applied voltage, frequency and pre-load of rotor as well as showed the characteristics of typical drooping torque-speed, large torque and high speed. So, we think that this flat-type $L_{-}$-$B_{8}$ mode USM has characteristics of enough torque and velocity to be usable for applications in forwarding device of an electric card or a paper, etc.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3435-3454
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• 2016

Device-to-device (D2D) communication is a potential solution to the incessant increase in data traffic on cellular networks. The greatest problem is how to control the interference between D2D users and cellular mobile users, and between D2D users themselves. This paper proposes a solution for this issue by putting the full control privilege in cellular network using the software-defined networking (SDN) concept. A software virtual switch called Open vSwitch and several components are integrated into mobile devices for data forwarding and radio resource mapping, whereas the control functions are executed in the cellular network via a SDN controller. This allows the network to assign radio resources for D2D communication directly, thus reducing interference. This solution also brings out many benefits, including resource efficiency, energy saving, topology flexibility, etc. The advantages and disadvantages of this architecture are analyzed by both a mathematical method and a simple implementation. The result shows that implementation of this solution in the next generation of cellular networks is feasible.