• Journal of electromagnetic engineering and science
• /
• v.14 no.4
• /
• pp.346-348
• /
• 2014

A dispersion analysis is performed to estimate the stopband characteristics of electromagnetic bandgap (EBG) structures with defected ground structures (DGS) of various shapes. Design guidelines are suggested for both elliptical and rectangular DGS patterns that result in a maximum stopband bandwidth for a given perforation area. This method provides a basis for numerical optimization techniques that can be used in synthesizing DGS shapes to meet bandgap requirements and layout constraints.

• Journal of Advanced Navigation Technology
• /
• v.25 no.5
• /
• pp.403-408
• /
• 2021

Harmony Search(HS) algorithm is an emerging meta-heuristic optimization algorithm, which is inspired by the music improvisation process and has been successfully applied to solve different optimization problems. In order to further improve the performance of HS, this paper proposes a new method which is called Fast Harmony Search(FSH) algorithm. For the purpose, this paper suggest a method to unify two independent improvisation processes by newly defining the boundary value of a object variable using HM. As the result, the process time of the algorithm is shorten and explicit decision of bandwidth is no more needed. Furthermore, exploitative power of random selection is improved. The numerical results reveal that the proposed algorithm can find better solutions and is faster when compared to the conventional HS.

• Journal of Korea Multimedia Society
• /
• v.11 no.12
• /
• pp.1730-1738
• /
• 2008

Quality of Service (QoS) Guarantees grant ways for service providers to establish service differentiation among subscribers. On the other hand, service subscribers are also assured the level of service they paid for. In addition, the efficient level of service quality can be selected according to the subscribers' needs thus ensuring efficient use of available bandwidth. While network utility optimization techniques assure certain QoS metrics, a number of situations exist where some QoS goals are not met. The optimality of the network parameters is not mandatory to guarantee specified QoS levels. This paper proposes a joint data rate and power control scheme that guarantees service contract QoS level to a subscriber using Goal Programming. In using goal programming, this paper focuses on finding the range of feasible solutions as opposed to solving for the optimal. In addition, in case no feasible solution is found, an acceptable compromised solution is solved.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.9A
• /
• pp.856-867
• /
• 2006

This paper proposes a new algorithm for opportunistic scheduling that take advantage of both multiuser diversity and power control. Motivated by the multicast RTS and priority-based CTS mechanism of OSMA protocol, we propose an opportunistic packet scheduling with power control scheme based on IEEE 802.11 MAC protocol. The scheduling scheme chooses the best candidate receiver for transmission by considering the SINR at the nodes. This mechanism ensures that the transmission would be successful. The power control algorithm on the other hand, helps reduce interference between links and could maximize spatial reuse of the bandwidth. We then formulate a convex optimization problem for minimizing power consumption and maximizing net utility of the system. We showed that if a transmission power vector satisfying the maximum transmission power and SINR constraints of all nodes exist, then there exists an optimal solution that minimizes overall transmission power and maximizes utility of the system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.9
• /
• pp.944-949
• /
• 2003

In this paper, the double balance mixer(DBM) for Ku-band LNB using InGaP/GaAs HBT process is suggested for the characteristics of low DC power consumption, low noise figure, low intermodulation distortion and wide dynamic range. The 5 dB conversion gain, 14 dB NF, bandwidth 17.9 GHz and 50.34 dBc IMD are obtained under RF input power of -23 dBm, with bias condition as 3 V and 16 mA. The linearity of InGaP/GaAs HBT, the broad band input matching scheme and the optimization of bias point result in the low IMD, the broad bandwidth and the low power consumption characteristics.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2315-2326
• /
• 2016

This paper discusses the elimination of DC voltage deviation and the enhancement of load current sharing accuracy in multi-terminal high voltage direct current (MT-HVDC) systems. In order to minimize the power line losses in different parallel network topologies and to insure the stable operation of systems, a decentralized control method based on a modified droop control is presented in this paper. Averaging the DC output voltage and averaging the output current of two neighboring converters are employed to reduce the congestion of the communication network in a control system, and the decentralized control method is implemented. By minimizing the power loss of the cable, the optimal load current sharing proportion is derived in order to achieve rational current sharing among different converters. The validity of the proposed method using a low bandwidth communication (LBC) network for different topologies is verified. The influence of the parameters of the power cable on the control system stability is analyzed in detail. Finally, transient response simulations and experiments are performed to demonstrate the feasibility of the proposed control strategy for a MT-HVDC system.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.9
• /
• pp.25-32
• /
• 2009

Recently, research for Network-on-chip(NoC) is progressing. However, due to the increase of system complexity and demand on high performance, conventional copper-based electrical interconnect would be faced with the design limitation of performance, power, and bandwidth. As an alternative to these problems, combined use of Electrical Interconnects(EIs) and Optical Interconnects(OIs) has been introduced. In this paper we propose efficient routing optimization strategy and hybrid switch architecture, which use OIs for critical path and EIs for non-critical path. The proposed method shows up to 25% performance improvement and 38% power reduction.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.1
• /
• pp.43-51
• /
• 2012

This paper presents the design optimization technique for a phase interpolator(PI) and suggests the inductor-loaded PI structure for low power consumption suitable for high-speed applications. An analytical study leads to the design criterion composed of the process constants for the minimum power consumption and the proposed inductor-loaded PI reduces the power by half with determined bandwidth and gain of PI. Designed 7-bit PI using $0.13{\mu}m$ 1.2V CMOS technology consumes $721.2{\mu}W$ in 12GHz with inductor and the suggested optimization technique.

• Journal of IKEEE
• /
• v.7 no.1 s.12
• /
• pp.72-79
• /
• 2003

Classical designs of optical transimpedance preamplifier for p-i-n photodiode receiver circuits generally employ common source transimpedance input stages. In this paper, we explore the design of a class of current-mode optical transimpedance preamplifier based upon common gate input stages. A feature of current-mode optical transimpedance preamplifier is high gain and high bandwidth. The bandwidth of the transimpedance preamplifier can also be increased by the capacitive peaking technique. In this paper we included the development and application of a circuit analysis technique based on the minimum noise. We develop a general formulation of the technique, illustrate its use on a number of circuit examples, and apply it to the design and optimization of the low-noise transimpedance amplifier. Using the noise minimization method and the capacitive peaking technique we designed a transimpedance preamplifier with low noise, high-speed current-mode transimpedance preamplifier with a 1.57GHz bandwidth, and a 2.34K transimpedance gain, a 470nA input noise current. The proposed preamplifier consumes 16.84mW from a 3.3V power supply.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.4
• /
• pp.140-144
• /
• 2015

Effects of the shape, the size and the material of head mass on performances of tonpilz transducer were studied with a finite element method. The shape of head mass was changed with an angle between symmetric axis and side of head mass of transducer from 0 to 60 degree. As a result of the simulations, the bandwidth leached to 86.4 % at 35.5 degree in case of Al head mass. The size of head mass showed a decrease in the power of transducer with little change of bandwidth. For the Ti head mass, the transmitted power showed 100 % increase with a bandwidth of 88.1 % even though the weight of the head mass increased to 167 % of Al. This can be attributed to the mechanical properties like elastic modulus of Ti relative to Al.