• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.4
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• pp.153-156
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• 1984

A local area network(LAN) controller is designed according to non-persistent CSMA protocols. By meas of a buffer register, a microcomputer interfaces with the LAN controller. To keep bus utilization near the optimal efficiencies, the transmission intervals are adjusted as a function of $2^n$. A message in the form of a packet consisting of 128bytes is transitted to the bus. The maximum transmission rate of 19.2Kbps is obtained at layer 1.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2620-2633
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• 1996

In this paper, a new high-speed local area network using a dual mode switching access (DMSA) protocol implemented on a dual unidirectional bus is described. By utilizing the implicit positionalordering of stations on a unidirectional bus, the proposed system switches between random access mode and the token access model withoug unnecessary delay. Therefore, unlike other hybrid systems such as Buzz-net and Z-net, DMSA does not show a rapid degradation in performance as the load increases. We obtain the average channel utilization and the average access delay by using a simplified analytic model. The numerical results obtained via analysis are compared to the simulation resuls for a partial validation of the approximate model. The performance characteristics of DMSA are superior delay-throughput characteristics at light and medium loads, compared to compared to other LAN systems, and the capability of providing a single active station with full capabity of the channel.

• Korean Journal of Labor Studies
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• v.23 no.2
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• pp.109-139
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• 2017

In light that solidarity movements become significant under the situation of 'labor and labor movement' crisis, our study pays attention to the fact that the Hope Bus campaigns made remarkable achievements, and aims to figure out how those campaigns were successful, by focusing on their solidarity networking. The successful operating conditions of solidarity networking in the Hope Bus campaigns are examined in three aspects - the conditions of triggering, forming, and activating. The solidarity networking of Hope Bus campaigns were mainly triggered by the injustice of layoffs by Hanjin Heavy Industry, aerial protest by Jin-sook Kim, and the tragic symbol of the protest site (Crane no. 85). The solidarity movement of Hope Bus could be formed by the mutual trust and cohesive team-building of key network brokers, their utilization and expansion of social movement networks, and massive ripple effect of SNS-mediated communication. The solidarity networking of Hope Bus was effectively activated by open and de-hierarchical operations of the central planning group, active solidarity activities of participant groups, and the provision of 'heuristic experience' for developing the sensibility to labor solidarity. The virtuous combination of those three operating conditions leads to the building of unified forces among social movements, massive civil participation, and meaningful movement outcomes, through the solidarity networking of Hope Bus campaigns.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.257-266
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• 2007

In On-Chip bus, the arbitration scheme is one of the critical factors that decide the overall system performance. The arbitration scheme used in traditional shared bus is the master-side arbitration based on the request and grant signals between multiple masters and single arbiter. In the case of the master-side arbitration, only one master and one slave can transfer the data at a time. Therefore the throughput of total bus system and the utilization of resources are decreased in the master-side arbitration. However in the slave-side arbitration, there is an arbiter at each slave port and the master just starts a transaction and waits for the slave response to proceed to the next transfer. Thus, the unit of arbitration can be a transaction or a transfer. Besides the throughput of total bus system and the utilization of resources are increased since the multiple masters can simultaneously perform transfers with independent slaves. In this paper, we implement and analyze the arbitration schemes for the Multi-Layer AHB BusMatrix based on the slave-side arbitration. We implement the slave-side arbitration schemes based on fixed priority, round robin and dynamic priority and accomplish the performance simulation to compare and analyze the performance of each arbitration scheme according to the characteristics of the master and slave. With the performance simulation, we observed that when there are few masters on critical path in a bus system, the arbitration scheme based on dynamic priority shows the maximum performance and in other cases, the arbitration scheme based on round robin shows the highest performance. In addition, the arbitration scheme with transaction based multiplexing shows higher performance than the same arbitration scheme with single transfer based switching in an application with frequent accesses to the long latency devices or memories such as SDRAM. The improvements of the arbitration scheme with transaction based multiplexing are 26%, 42% and 51%, respectively when the latency times of SDRAM are 1, 2 and 3 clock cycles.

• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.225-232
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• 2012

Purpose: Accurate monitoring of information from various agricultural vehicles is one of the most important factors for appropriate management strategy of field operations. While there has been a number of study and design on applications of sensors and actuators for data acquisition and control system in tractor, incompatibility between various customized hardware and software has become a major obstacle to the universal deployment in real field operation. International standard for implementation of electronic control unit (ECU) in agricultural vehicles has becoming a mandatory requirement for inter-operation compatibility in the international trade of agricultural vehicle industries. The ISO 11783 standard is basically based upon well known communication technology designated using the controller area network (CAN) bus. While CAN bus could provide 1.0 Mbps of communication speed, the standard only recommended 250 kbps. Methods: This study presents the implementation and evaluation of ISO 11783 for tractor electronic control units (TECU)with a higher transmission rate from multiple ECU than 250 kbps. Throughput and loss rate of the developed prototype were calculated across manipulated bus load for laboratory experimental tests, and the maximum requirement of transmission rate by ISO 11873 was satisfied with lower than 60% of bus load. Results: Field tests with a TECU implemented to process messages from global positioning system (GPS) receiver resulted that the root mean square error of position information was lower than 4 m with 0.5 m/s as a travelling speed. Conclusions: Results of this study represent the utilization of the international standard ISO 11783 to providepractical developments in terms with the inter-operability of TECU.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.5
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• pp.14-22
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• 2011

This study is to estimate delay time model of signalized intersection by using travel data of Bus Information System. BIS, which applies the advanced information technology to an existing bus system, has been developing and operating in many cities. However, even though some useful traffic informations have been collected from BIS operation, utilization of real-time data to the traffic operation has not been promoted due to the inhomogeneity of modal speeds. Accordingly, in this study, a fundamental research is performed for traffic controls in urban areas and providing a traffic information throughout a methodology for estimating delay time using the data from BIS was developed. This delay time model setting bus travel time excluding service time of a bus stop as explanatory variables was constructed as a regression model, and the coefficient of determination of a linear regression model most highly appeared as 0.826. As a result of performing T-test with field survey values and model estimation values for verifying constructed models statistically, it was analyzed to be statistically significant in a confidence level of 95%.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.600-603
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• 2000

In this paper, we propose the design method of distributed control system using Controller Area Network (CAN). CAN is an advanced serial communication protocol for distributed real-time control systems. It is a contention-based multi-master network whose timeliness properties come from its collision resolution algorithm which gives a high schedulable utilization and guaranteed bus access latency. With proposed method using CAN, we apply to robot controller. The effectiveness of proposed method is demonstrated by the simulation and experiment.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.455-460
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• 2010

Recent increases in the road and rail infrastructure, but the urban traffic problems such as accidents, congestion are increasing. The reason is that the high cost and lack of accessibility of railway transportation, the low quality of road services, and efficient transport links, etc.. The developments of a variety of policy and technical means are being performed to solve these problems. Among them, the Bimodal Tram which is combined low-cost of bus and high service quality of railway transportation is attracting attention. In this paper, the development status of technology and efficient utilization of operational and infrastructure elements for the operational efficiency, safety and passenger comfort of Bimodal Tram is studied.

• Journal of the Korea Society of Computer and Information
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• v.8 no.1
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• pp.84-89
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• 2003

In this Paper, an improved protocol is proposed by supplementing a control station for transmission cycle management. This protocol is proposed to complement the shortcomings of the conventional L-Expressnet protocol which is used for round robin process in bus topology. We analyzed the improved protocol in channel utilization viewpoint and compared the result with that of the conventional protocol. From this result, we showed that the channel utilization of the improved protocol is superior to that of the conventional protocol when a maximum normalized propagation delay is increased.

• Journal of the Korea Society of Computer and Information
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• v.8 no.2
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• pp.106-111
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• 2003

In this Paper, an improved protocol is proposed by supplementing a control station for transmission cycle management and slot-extension function. This protocol is proposed to complement the shortcomings of the conventional L-Expressnet protocol which is used for round robin process in bus topology. We analyzed the improved protocol in channel utilization viewpoint and compared the result with that of the conventional Protocol. From this result, we showed that the channel utilization of the improved protocol is superior to that of the conventional protocol when a maximum normalized propagation delay is increased.