• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.88-92
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• 1999

As a part of work to simulate electromagnetic environments for Hardware-In-the-Loop(HIL) simulation, the dynamic trajectory is modeled by the Way-points method and the Event-driven method for the aerial and the naval targets. The simulated results show that the Way-points method and the Event-driven method are appropriate to simulate a low speed and a high speed target respectively.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.184-191
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• 2020

Avionics System Integration Laboratory is the integrated test environment for integration and verification of avionics systems. When real equipment can not be used in the laboratory for various reasons, software models should be needed. Because there hasn't been any standardized method for the models so that it is difficult to reuse the developed models, the need for a framework to develop the avionics software models was emerged. We adopted DEVS(discrete event system specification) formalism as the standardized modeling method for the avionics software models. Due to DEVS formalism is based on event-driven algorithm, it doesn't accord a legacy system which has sequential and periodic algorithms. In this paper, we propose real-time event-driven modeling and simulation method for SIL to overcome these restrictions and to maximize reusability of avionics models through the analysis of the characteristics and the limitations of avionics models.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.3
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• pp.34-42
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• 2013

In this study, we develop a method for analyzing business process based on the event-driven process chain (EPC) model. The method consists of five stages such as identifying abnormal events, finding causes for the abnormal events and problems caused by the abnormal events, making cause-and-effect chains, drawing root-cause map, and defining improvement areas. We illustrate how to apply the method with some examples for the domestic registered mail delivery process.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.3
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• pp.85-90
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• 2015

In this paper, anew parallel event-driven logic simulation is proposed. As the proposed prediction-based parallel event-driven simulation method uses both prediction data and actual data for the input and output values of local simulations executed in parallel, the synchronization overhead and the communication overhead, the major bottleneck of the performance improvement, are greatly reduced. Through the experimentation with multiple designs, we have observed the effectiveness of the proposed approach.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.3
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• pp.57-64
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• 2019

In this paper, an efficient prediction-based parallel simulation method using spatially partial simulation strategy is proposed for improving both the performance of the event-driven gate-level timing simulation and the debugging efficiency. The proposed method quickly generates the prediction data on-the-fly, but still accurately for the input values and output values of parallel event-driven local simulations by applying the strategy to the simulation at the higher abstraction level. For those six designs which had used for the performance evaluation of the proposed strategy, our method had shown about 3.7x improvement over the most general sequential event-driven gate-level timing simulation, 9.7x improvement over the commercial multi-core based parallel event-driven gate-level timing simulation, and 2.7x improvement over the best of previous prediction-based parallel simulation results, on average.

• Journal of Computational Design and Engineering
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• v.1 no.4
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• pp.233-242
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• 2014

A magnetically levitated vehicle (Maglev) system is under commercialization as a new transportation system in Korea. The Maglev is operated by an unmanned automatic control system. Therefore, the plan of train operation should be carefully established and validated in advance. In general, when making a train operation plan, statistically predicted traffic data is used. However, a traffic wave often occurs in real train service, and demand-driven simulation technology is required to review a train operation plan and service quality considering traffic waves. We propose a method and model to simulate Maglev operation considering continuous demand changes. For this purpose, we employed a discrete event model that is suitable for modeling the behavior of railway passenger transportation. We modeled the system hierarchically using discrete event system specification (DEVS) formalism. In addition, through implementation and an experiment using the DEVSim++ simulation environment, we tested the feasibility of the proposed model. Our experimental results also verified that our demand-driven simulation technology can be used for a priori review of train operation plans and strategies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2473-2492
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• 2012

Energy conservation is a vital issue in wireless sensor networks. Recently, employing mobile sinks for data gathering become a pervasive trend to deal with this problem. The sink can follow stochastic or pre-defined paths; however the controlled mobility pattern nowadays is taken more into consideration. In this method, the sink moves across the network autonomously and changes its position based on the energy factors. Although the sink mobility would reduce nodes' energy consumption and enhance the network lifetime, the overhead caused by topological changes could waste unnecessary power through the sensor field. In this paper, we proposed EEDARS, an energy-efficient dual-sink algorithm with role switching mechanism which utilizes both static and mobile sinks. The static sink is engaged to avoid any periodic flooding for sink localization, while the mobile sink adaptively moves towards the event region for data collection. Furthermore, a role switching mechanism is applied to the protocol in order to send the nearest sink to the recent event area, hence shorten the path. This algorithm could be employed in event-driven and multi-hop scenarios. Analytical model and extensive simulation results for EEDARS demonstrate a significant improvement on the network metrics especially the lifetime, the load and the end-to-end delay.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.157-161
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• 2009

In recent years, there is a remarkable progress in ICTs (Information and Communication Technologies), and then many attempts to apply ICTs to other industries are being made. In the field of disaster managements, ICTs such as RFID (Radio Frequency IDentification) and USN (Ubiquitous Sensor Network) are used to provide safe environments. Actually, various types of early warning systems using USN are now widely used to monitor natural disasters such as floods, landslides and earthquakes, and also to detect human-caused disasters such as fires, explosions and collapses. These early warning systems issue alarms rapidly when a disaster is detected or an event exceeds prescribed thresholds, and furthermore deliver alarm messages to disaster managers and citizens. In general, these systems consist of a number of various sensors and measure real-time stream data, which requires an efficient and rapid data processing technique. In this study, an event-driven architecture (EDA) is presented to collect event effectively and to provide an alert rapidly. A publish/subscribe event processing method to process simple event is introduced. Additionally, a complex event processing (CEP) technique is introduced to process complex data from various sensors and to provide prompt and reasonable decision supports when many disasters happen simultaneously. A basic concept of CEP technique is presented and the advantages of the technique in disaster management are also discussed. Then, how the main processing methods of CEP such as aggregation, correlation, and filtering can be applied to disaster management is considered. Finally, an example of flood forecasting and early alarm system in which CEP is incorporated is presented It is found that the CEP based on the EDA will provide an efficient early warning method when disaster happens.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1123-1140
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• 2019

Many Internet of Things (IoT) applications involving bursty traffic have emerged recently with event detection. A power management scheme qualified for uplink bursty traffic (PM-UBT) is proposed by distinguishing between bursty and general uplink traffic patterns in the IEEE 802.11 standard to balance energy consumption and uplink latency, especially for stations with limited power and constrained buffer size. The proposed PM-UBT allows a station to transmit an uplink bursty frame immediately regardless of the state. Only when the sleep timer expires can the station send uplink general traffic and receive all downlink frames from the access point. The optimization problem (OP) for PM-UBT is power consumption minimization under a constrained buffer size at the station. This OP can be solved effectively by the bisection method, which demonstrates a performance similar to that of exhaustive search but with less computational complexity. Simulation results show that when the frame arrival rate in a station is between 5 and 100 frame/second, PM-UBT can save approximately 5 mW to 30 mW of power compared with an existing power management scheme. Therefore, the proposed power management strategy can be used efficiently for delay-intolerant uplink traffic in event-driven IoT applications, such as health status monitoring and environmental surveillance.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.1
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• pp.17-24
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• 2015

Smart factory requires 4 Zero factors including Zero Waiting-time, Zero Inventory, Zero Defect, Zero Down-time) that needs IT convergence for production resources of 4M1E(Man, Machine, Material, Method, Energy) in real time and event processing in all type of manufacturing enterprises. This paper will be explaining about core emerging production IT convergence technologies including cyber device security, 4M1E integration, real time event driven architecture, common platform of manufacturing standard applications, smart factory to-be model for small and medium manufacturing enterprises.