• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.5
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• pp.29-36
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• 2002

In the maintenance and retrofit planning of a bridge system, the optimal strategy for inspection and repair are suggested by minimizing the expected total life-cycle cost, which includes the initial cost, the costs of inspection, repair, and failure. Degradation of seismic performance is modeled by using a damage function. And failure probability is computed according to the degree of damage detection by random vibration theory and the event tree analysis. As an example to illustrate the proposed approach, a 10-span continuous bridge structure is used. The numerical results show that the optimum number of the inspection and the repair are increased, as the seismic intensity is increased and the soil condition of a site becomes more flexible.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.115-122
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• 1998

For digital engine control timings, such as ignition, are based on the crank shaft angle. Therefore, it is very important that the angle of the crank shaft can be detected with accuracy for optimal ignition timing. Sequential multi-point injection(MPI) systems that have independent injection events for each cylinder, are used to inject an accurate quantity of fuel, and to cope with varying engine status promptly. In this study the distributorless ignition timing. A crankshaft position sensor has been installed such that it generates a number of pulses per crankshaft revolution to permit accurate detection of the crank shaft angle. An event detecting algorithm has been developed, which detects the crank shaft pulses generated by the position sensor, and the software outputs the required control signals at given crank angle values. We clarified that the hardware method is the best way to increase the performance of the control system, because the event detecting duration T(1+2)max becomes zero.

• Korean Management Science Review
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• v.30 no.1
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• pp.91-102
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• 2013

This study has an aim to analyze the effects of ADS on conjunctivitis patients among the residents of Seoul, Korea, between 2005 and 2008. For this purpose, the number of medical services provided to conjunctivitis patients on the days of windblown dust storms and the days without any windblown dust storms were analyzed by conducting paired t-test. The interactive effects of the ADS density and the accuracy of ADS forecast on the fluctuation of conjunctivitis cases were also investigated. The results showed that, even with an accurate forecast issued 24 hours prior to the event, the average number of medical services provided for conjunctivitis was higher on the index days than the comparison days. On the other hand, in cases of failure to provide an accurate forecast 24 hours prior to the ADS event, the number of conjunctivitis attacks reported was statistically significantly higher on the index days for 3~5 days after the occurrence of a dust storm in relation to the comparison days. We also found that the rate of increase in asthma treatments on the index days with low level of $PM_{10}$ concentration rather than high $PM_{10}$ level was more significant for all lag days. This study provides evidence that ADS events are significantly associated with conjunctivitis symptoms and the failure to forecast ADS events with low $PM_{10}$ level might aggravate conjunctivitis disease.

• International journal of advanced smart convergence
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• v.5 no.3
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• pp.32-39
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• 2016

With the help of a small wearable device, patients reside in an isolated village need constant monitoring which may increase access to care and decrease healthcare delivery cost. As the number of patients' requests increases in simultaneously manner, the web service gateway located in the village hall encounters limitations for performing them successfully and concurrently. The gateway based RESTful technology responsible for handling patients' requests attests an internet latency in case a large number of them submit toward the gateway increases. In this paper, we propose the design tasks of the web service gateway for handling concurrency events. In the procedure of designing tasks, concurrency is best understood by employing multiple levels of abstraction. The way that is eminently to accomplish concurrency is to build an object-oriented environment with support for messages passing between concurrent objects. We also investigate the performance of event-driven architecture for building web service gateway using node.js. The experiments results show that server-side JavaScript with Node.js and MongoDB as database is 40% faster than Apache Sling. With Node.js developers can build a high-performance, asynchronous, event-driven healthcare hub server to handle an increasing number of concurrent connections for Remote Healthcare Monitoring System in an isolated village with no access to local medical care.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.191-200
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• 2007

We propose the QoS (Quality of Service) assurance model for AMR (Adaptive MultiRate) voice users considering the capacity and service quality jointly in downlink WCDMA system. For this purpose, we introduce a new system performance measure and the number-based AMR mode allocation scheme. The proposed number-based AMR mode allocation can be operated only with the information of total number of ongoing users. Therefore, it can be more simply implemented than the existing power-based allocation. The proposed system performance measure considers the stochastic variations of AMR modes of ongoing users and can be analytically obtained using CTMC (Continuous Time Markov Chain) modeling. In order to validate the proposed analytical model, a discrete event-based simulation model is also developed. The performance measure obtained from the analytical model is in agreement with the simulation results and is expected to be useful for parameter optimization.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.235-243
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• 2007

Sensor network is used to obtain sensing data in various area. The interval to sense the events depends on the type of target application and the amounts of data generated by sensor nodes are not constant. Many applications exploit long sensing interval to enhance the life time of network but there are specific applications that requires very short interval to obtain fine-grained, high-precision sensing data. If the number of nodes in the network is increased and the interval to sense data is shortened, the amounts of generated data are greatly increased and this leads to increased amount of packets to transfer to the network. To transfer large amount of packets fast, it is necessary that the delay between successive packet transmissions should be minimized as possible. In Sensor network, since the Operating Systems are worked on the event driven, the Timer Event is used to transfer packets successively. However, since the transferring time of packet completely is varies very much, it is very hard to set appropriate interval. The longer the interval, the higher the delay and the shorter the delay, the larger the fail of transfer request. In this paper, we propose ESTEO which reduces the delay between successive packet transmissions by using SendDone Event which informs that a packet transmission has been completed.In ESTEO, the delay between successive packet transmissions is shortened very much since the transmission of next packet starts at the time when the transmission of previous packet has completed, irrespective of the transmission timee. Therefore ESTEO could provide high packet transmission rate given large amount of packets.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.2
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• pp.387-396
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• 2016

As the number of people using digital devices has increased, the digital forensic, which aims at finding clues for crimes in digital data, has been developed and become more important especially in court. Together with the development of the digital forensic, the anti-forensic which aims at thwarting the digital forensic has also been developed. As an example, with anti-forensic technology the criminal would delete an digital evidence without which the investigator would be hard to find any clue for crimes. In such a case, recovery techniques on deleted or damaged information will be very important in the field of digital forensic. Until now, even though EVTX(event log)-based recovery techniques on deleted files have been presented, but there has been no study to retrieve event log data itself, In this paper, we propose some recovery algorithms on deleted or damaged event log file and show that our recovery algorithms have high success rate through experiments.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.125-132
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• 2015

This paper presents an event data delivery scheme for wireless sensor networks that use a GTS-based channel allocation scheme. Many sensor nodes can share a GTS channel for sending their normal data to the sink node. When there is an event at a node, the node makes a temporal route to the sink node and the nodes of the route can use the GTS channel in a privileged access. This scheme controls the backoff number effectively so the data delivery priority is given to the nodes of that route. Simulation results show that the event data delivery of the proposed scheme outperforms at the end-to-end transfer delay and jitter characteristics. The proposed scheme can effectively gather the event data using the guaranteed GTS channel of the route in proposed scheme.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.29-37
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• 2014

Telemetry, satellite event and error information are used to check the satellite status in ground station. Different from telemetry which only informs the parameter value, event and error gives explicit information of a certain operation or status. Event also contains ground action information because every command execution is logged as event. Currently, those information is gathered and applied only for monitoring of the satellite. However, the load of the operation is getting grown because of the excessively increased information of the satellite with the number of satellite increasement. Also, the process of reporting problem to developer (or an expert) induce time delay for satellites fault management. In this paper, we propose a satellite operation assistant system which collects event sequence and stores in different group by its feature, and then recommends or executes an appropriate action for the identified abnormal state. This system is applicable to on board system for resolving LEO-satellite autonomous fault situation since is has limited contact time.

• Korean Security Journal
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• no.30
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• pp.7-32
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• 2012

Korea faces The 2014 Incheon Asian Games and 2018 Pyungchang Winter Olympics. It is imperative to hold a safe event for the economic benefits, enhancing Korea's image, social integration, national harmony and unity in order to be evaluated as a successful international event. Furthermore, since the international event tends to draw many spectators, the host country must be ready to accommodate a large number of injured people in the event of an accident or terror attack. As stadiums for international events are where a large number of spectators gather in, a large refuge is essential, when dangerous situations happen. In this study, evacuation simulation was conducted using three scenarios in order to predict escape behaviors of spectators during the large escape by destruction of safety systems of stadiums and assess escape safety. As the result, the following results and proposals were extracted. Firstly, it is considered that dangerous situations during the security of stadiums should be predicted in advance and concrete plans for a large refuge of spectators have to be established to minimize damage. Secondly, it was found that the reduction in evacuation exits has an important impact on evacuation in an emergency situation. It implies that securing escape exits are quite important. Thirdly, there were areas where spectators stayed, due to blocked escape exits, while they were dispersed and concentrated at once. It demonstrates that security plans considering properties of facilities are required to solve these problems.