• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.7
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• pp.535-542
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• 2013

Coordinated multi-point transmission (CoMP) is considered to be a promising technique to improve the throughput for LTE-Advanced systems. One important approach for CoMP is Joint Transmission (JT). However, the analytical model of JT has not been fully studied, as user equipments (UEs) receiving the desired signals from an adjacent base station (BS) as well as serving BS, or only serving BS were not distinguished. We derive a new analytical model to describe the call admission control in JT based systems. The performance measures of interest are the call blocking probability, and resource utilization. Furthermore, we compare the performance of JT-based systems and non-JT- based systems. The analytical results are in reasonable agreement with the simulation results.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.157-160
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• 2002

When the teleoperation system has a signal transmission time delay between slave system and control system, the position tracking performance of the slave system and system stability are likely to be deteriorated. This paper proposes a force reflecting position control scheme for teleoperation system with signal transmission time delay. The proposed scheme not only satisfy the system internal stability but also improves the position tracking performance with disturbance rejection capability. The simulation results show that the proposed control method provides excellent performances.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.11
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• pp.1081-1085
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• 2010

In the wireless sensor networks, power consumption and interference among the nodes can be reduced by using the transmission power control. Because link quality is changed by spatial and temporal effect, link failures are frequently occurred. In order to adapt to link quality variation, existing transmission power control schemes broadcast beacon messages periodically to neighbor nodes and control the transmission power dynamically. However, it can effect on the time and energy overhead according to period of transmission power control. In this paper, the dynamic method of transmission power control by the link quality variation and variable period are proposed. When a link quality is unstable, the control duty cycle is reduced and the link quality is agilely maintained. In contrast, when link quality is stable, the control period is increased and control overhead is decreased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9A
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• pp.878-883
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• 2006

New emerging wireless broadband internet can make many broadband multimedia services. The networked intelligent mobile robot service is one of the new services. In the networked robot control, both the on-line real-time control and the reliability of control data transmission are very important. Considering the real-time control and data reliability, an efficient transmission method based on UDP protocol is proposed. The proposed method allocates the priority to the robot control data and the transmission of the robot data at the base station is carried out in duplicate manner. NS-2 simulation results show that the proposed scheme has a very low packet delay and low packet errors.

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

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.158-163
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• 2005

Competitive electricity markets necessitate equitable methods for allocating transmission usage in order to set transmission usage charges and congestion charges in an unbiased and an open-accessed basis. So in competitive markets it is usually necessary to trace the contribution of each participant to line usage, congestion charges and transmission losses, and then to calculate charges based on these contributions. A UPFC offers flexible power system control, and has the powerful advantage of providing, simultaneously and independently, real-time control of voltage, impedance and phase angle, which are the basic power system parameters on which sys-tem performance depends. Therefore, UPFC can be used efficiently and flexibly to optimize line utilization and increase system capability and to enhance transmission stability and dampen system oscillations. In this paper, a mathematical approach to allocate the contributions of system users and UPFCs to transmission system usage is presented. The paper uses a dc-based load flow modeling of UPFC-inserted transmission lines in which the injection model of the UPFC is used. The relationships presented in the paper showed modified distribution factors that modeled impact of utilizing UPFCs on line flows and system usage. The derived relationships show how bus voltage angles are attributed to each of changes in generation, injections of UPFC, and changes in admittance matrix caused by inserting UPFCs in lines. The relationships derived are applied to two test systems. The results illustrate how transmission usage would be affected when UPFC is utilized. The relationships derived can be adopted for the purpose of allocating usage and payments to users of transmission network and owners of UPFCs used in the network. The relationships can be modified or extended for other control devices.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.943-950
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• 2005

Recently, many of researches on stream transmission for satisfying each of different real-time transmission condition of the multimedia data that demands various service quality through high-speed networks have been studied actively. In this paper, we design a scheme that discriminately reserves the network resources for the transmission of each multimedia application and propose a bandwidth allocation scheme for improving the utilization ratio of free resources. And we also propose a pipelining scheme for providing flexible real-time transmission. The proposed schemes can be used to support a real-time transmission by applying feedback transmission control method based on receiving buffer for guaranteeing the synchronization conditions requested by the multimedia data. Moreover, we propose a transmission control scheme that can take the amount of network resources down to the minimum amount within the range of permissible error-range under the guarantee with no quality degradation simultaneously when the bottleneck is caused by the network congestion. Finally, we propose a dynamic bandwidth smoothing scheme that can smooth the maximum bandwidth to the demand of each video steam for giving continuous transmission to the delay sensitive video steam between senders and receivers.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.2
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• pp.197-203
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• 2004

A real-time network in a distributed control system plays an important role for the reliable data transmission. Compared to the field-buses used in the past, TCP/IP protocol on the top of Ethered provides a compatibility between applications as well as an economical method to develop softwares. This paper proposes a modified TCP/IP structure for IEEE-1394 network, with which asynchronous and isochronous data transmission is selectively used for the real-time data transmission in a distributed control system. This paper also shows the performance of the proposed protocol by experiments.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.484-487
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• 1997

In this paper a simulation program for the powertrain control of a gasoline engine with automatic transmission is presented, The object-oriented programming approach has been pursued, and MATLAB/ SIMULINK was adopted for its environment. The purpose of the paper is to demonstrate the programmability of a control system in the object-oriented fashion so that the transferability of the objects is guaranteed. The program developed in the paper was applied to a gasoline engine and the mathematical models used in the paper were just adopted from the literature. It is shown that the simulation results and real experimental results coincide well. Therefore, it is expected that the program or objects made in the paper are useful for the automotive engineers when they design a new engine/transmission system or modify a part of existing system.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.68-84
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• 2000

A study to reduce the transient torque in shifting in automatic transmission has been very important issue. Recently it is really dominant to decrease the torque by using independent-acting hydraulic circuit because we can control the clutch pressure actively and elaborately. So we design the new hydraulic circuit to control the clutches in automatic transmission and make the module library of computer simulations, We apply the results to GM model automatic transmission and carry out 1longrightarrow4 shifting simulations. By this work we recognize the capability of active and elaborate clutch pressure control using new hydraulic circuit. In addition We develop the tool to simulate the powertrain system. It is easier to update and exchange the subsystem model or parameters than conventional simulation tools.