• International Journal of Highway Engineering
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• v.17 no.5
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• pp.93-103
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• 2015

PURPOSES : The purpose of this study is to present a linear programing optimization model for the design of lane-based lane-uses and signal timings for an isolated intersection. METHODS: For the optimization model, a set of constraints for lane-uses and signal settings are identified to ensure feasibility and safety of traffic flow. Three types of objective functions are introduced for optimizing lane-uses and signal operation, including 1) flow ratio minimization of a dual-ring signal control system, 2) cycle length minimization, and 3) capacity maximization. RESULTS : The three types of model were evaluated in terms of minimizing delay time. From the experimental results, the flow ratio minimization model proved to be more effective in reducing delay time than cycle length minimization and capacity maximization models and provided reasonable cycle lengths located between those of other two models. CONCLUSIONS : It was concluded that the flow ratio minimization objective function is the proper one to implement for lane-uses and signal settings optimization to reduce delay time for signalized intersections.

• Journal of information and communication convergence engineering
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• v.16 no.2
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• pp.72-77
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• 2018

This paper presents a novel channel capacity maximization method for a distorted $2{\times}2$ line-of-sight (LOS) multiple-input multiple-output (MIMO) link. A LOS MIMO link may be distorted by the influence of environmental factors such that the channel capacity of the LOS MIMO link may be degraded. By using the proposed method, the channel capacity of a distorted $2{\times}2$ LOS MIMO link can be the same as that of the ideal $2{\times}2$ LOS MIMO link. The proposed method employs an additional receiver antenna to maximize the channel capacity. In contrast to a $3{\times}2$ LOS MIMO link, a receiver circuit for a third receiving antenna is not necessary. Hence, the receiver for the proposed method is much simpler than that for a $3{\times}2$ LOS MIMO link. We determine the optimal position of the additional receiver antenna analytically. Simulation results show that the channel capacity can approach the ideal using the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.193-214
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• 2017

In this paper, we study the problem of network utility maximization in a CSMA based multi-hop wireless network. Existing work in this aspect typically adopted continuous time Markov model for performance modelling, which fails to consider the channel conflict impact in actual CSMA networks. To maximize the utility of a CSMA based wireless network with channel conflict, in this paper, we first model its weighted network capacity (i.e., network capacity weighted by link queue length) and then propose a distributed link scheduling algorithm, called CSMA based Maximal-Weight Scheduling (C-MWS), to maximize the weighted network capacity. We derive the upper and lower bounds of network utility based on C-MWS. The derived bounds can help us to tune the C-MWS parameters for C-MWS to work in a distributed wireless network. Simulation results show that the joint optimization based on C-MWS can achieve near-optimal network utility when appropriate algorithm parameters are chosen and also show that the derived utility upper bound is very tight.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.40-45
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• 2013

It is known that Reliability Differentiated Pricing (RDP) can improve the efficiency and benefits of consumers and producers. This paper examines the long-run social welfare maximization problem of the utility and presents a long-term reliability differentiated prices for firm capacity, based on customer outage costs. Then the applicability of the proposed pricing scheme is verified with a case study.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.398-399
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• 2006

The procurement of generation and transmission/Distribution capacity in vertically-integrated electric industry is sufficient by facility construction in suitable time. However, the introduction of competitive electricity market increase the efficiency of availability for facilities and fuels. As a result, long-term capacity procurement is required for stable demand-supply balance since it is expected to maintain their generation capacity at a minimum for profit maximization. In this paper, a new long-term capacity procurement mechanism is proposed, which is able to assure supplemental contribution in competitive electricity market.

• Journal of Integrative Natural Science
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• v.13 no.2
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• pp.69-75
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• 2020

Multiple Input Multiple Output (MIMO) is one of the important wireless communication technologies. This paper proposes MIMO system capacity enhancement by using convolution of periodic circulating vector signals. This signal represents statistical dependencies between transmission signal with discrete noise and receiver signal with the linear shifting of MIMO channel capacity by positive extents. We examine the channel capacity, outage probability and SNR of MIMO receiver by adding log determinant signal with validated in terms of numerical simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3B
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• pp.247-254
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• 2009

Over the last decade multiple-input and multiple-output (MIMO) systems have been actively researched and started to be deployed in wireless communications owing to the significant increase in channel capacity. In this paper, we propose a energy saving MAC protocol in systems by focusing on energy efficiency instead of capacity maximization. We considers the energy consumption together with the tradeoff between reliability (i.e., diversity) and throughput (i.e., multiplexing gain), and dynamically chooses an appropriate number of antennas for transmission. In computing the total energy consumption, we counts circuit energy as well as transmission energy. Naturally the circuit energy consumption is directly proportional to the number of active antennas. Through numerical analysis, we confirm that our power saving MAC scheme for MIMO considerably saves energy consumption compared to conventional capacity maximization schemes that use a fixed number of MIMO channels, for a given outage constraint. Our finding is that the capacity maximizing communication which possibly can be regarded best in terms of energy efficiency gives a different solution from the energy minimizing communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2613-2620
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• 2014

In this paper, we consider a full duplexing (FD) wireless cellular network where a central base station (BS) works in the FD mode while the downlink (DL) and uplink (UL) users work in the time division duplexing (TDD) mode. Since this FD system induces the inter-user interference from UL user to DL user, the main challenge for maximizing the system performances is user scheduling that makes a pair of DL user and UL user to use the same radio resource simultaneously. We formulate an optimization problem for user pairing to maximize the cell capacity and propose a suboptimal user scheduling algorithm with low complexity. This scheduling algorithm is designed in a way where the DL user with a better signal quality has a higher priority to choose its UL user that causes less interference. Simulation results show that the FD system using the proposed user scheduling algorithm achieves the optimal performance and significantly outperforms the conventional TDD system in terms of the cell capacity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1023-1033
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• 2007

This study considers a joint congestion control, routing and power control for energy-constrained wireless networks. A mathematical model is introduced which includes maximization of network utility, maximization of network lifetime, and trade-off between network utility and network lifetime. The framework would maximize the overall throughput of the network where the overall throughput depends on the data flow rates which in turn is dependent on the link capacities. The link capacity on the other hand is a function of transmit power levels and link Signal-to-Interference-plus-Noise-Ratio (SINR) which makes the power allocation problem inherently difficult to solve. Using dual decomposition techniques, subgradient method, and logarithmic transformations, a joint algorithm for rate and power allocation problems was formulated. Numerical examples for each optimization problem were also provided.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.812-813
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• 2007

The procurement of generation and transmission/Distribution capacity in vertically-integrated electric industry is sufficient by facility construction in suitable time. However, the introduction of competitive electricity market increase the efficiency of availability for facilities and fuels. As a result, long-term capacity procurement is required for stable demand-supply balance since it is expected to maintain their generation capacity at a minimum for profit maximization. In this paper, a new long-term capacity procurement mechanism is constructed, which is able to assure supplemental contribution in competitive electricity market.