• Journal of Korean Institute of Industrial Engineers
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• v.40 no.2
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• pp.163-171
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• 2014

Epidemic models are used to analyze the spreading of epidemic diseases, estimate public health needs, and assess the effectiveness of mitigation strategies. Modeling scope of an epidemic model ranges from the regional scale to national and global scale. Most of the epidemic models developed in Korea are at the national scale using the equation-based model. While these models are useful for designing and evaluating national public health policies, they do not provide sufficient details. As an alternative, individual-based models at the regional scale are often used to describe disease spreading, so that various mitigation strategies can be designed and tested. This paper presents an individual-based epidemic spreading model at regional scale. This model incorporates 2005 census data to build the synthetic population in the model representing Daejeon in 2005. The model's capability is demonstrated by an example where we assess the effectiveness of several mitigation strategies using the model.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.131-136
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• 2024

This paper deal with a method for calculating the continuity of Korea Augmentation Satellite System (KASS), which was completed in Korea in December 2023, and a plan to respond in the event that a continuity hazard situation occurs during operation. For this purpose, the International Civil Aviation Organization (ICAO) Satellite Based Augmentation System (SBAS) continuity standards, Wide Area Augmentation System (WAAS), and European Geostationary Navigation Overlay Service (EGNOS) continuity cases are examined in this paper. According to the measures recommended by the ICAO, when the number of continuity risks exceeds a certain level and the level drops drastically, various mitigation operations by country are implemented. Through this, if KASS does not meet ICAO continuity standards in the future, such measures can be referred to. In addition, this paper computes the short-term KASS continuity during the test broadcast period. Although continuity does not meet the ICAO standards, although this test period is too short, further meaningful analysis in the future is required. Additionally, this paper carried out an analysis of the timing and period to systematically calculate the meaningful value of continuity.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1043-1050
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• 2014

Obsolescent control systems for power systems are evolving into intelligent systems and connecting with smart devices to give intelligence to the power systems. As networks of the control system are growing, vulnerability is also increasing. The communication network of distribution areas in the power system connects closely to vulnerable environments. Many cyber-attacks have been founded in the power system, and they could be more critical as the power system becomes more intelligent. From these environment, new communication network architecture and mitigation method against cyber-attacks are needed. Availability and Fault Tree analysis used to show that the proposed system enhances performance of current control systems.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.622-633
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• 2015

The coexistence among different systems is a major problem in communications. Mutual interference between different systems should be analyzed and mitigated before their deployment. The paper focuses on two aspects that have an impact on the system performance. First, the coexistence analysis, i.e. evaluating the mutual interference. Second aspect is the coexistence techniques, i.e. appropriate system modifications that guarantee the simultaneous use of the spectrum by different technologies. In particular, the coexistence problem is analyzed between ultra-wide bandwidth (UWB) and narrow bandwidth (NB) systems emphasizing the role of spectrum sensing to identify and classify the NB interferers that mostly affect the performance of UWB system. A direct sequence (DS)-time hopping (TH) code design technique is used to mitigate the identified NB interference. Due to the severe effect of Narrowband Interference on UWB communications, we propose an UWB transceiver that utilizes spectrum-sensing techniques together with mitigation techniques. The proposed transceiver improves both the UWB and NB systems performance by adaptively reducing the mutual interference. Detection and avoidance method is used where spectrum is sensed every time duration to detect the NB interferer's frequency location and power avoiding it's effect by using the appropriate mitigation technique. Two scenarios are presented to identify, classify, and mitigate NB interferers.

• Journal of Korea Water Resources Association
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• v.39 no.11 s.172
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• pp.915-922
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• 2006

National Emergency Management Agency is planning a flood disaster mitigation system in urban area. This research is about analysis of runoff reduction efficiency of the alloted detention system which is one of flood disaster mitigation systems in urban area. The alloted detention system is composed of small to middle size detention facilities located in up and middle stream of urban basin. To analyze runoff reduction efficiency of alloted detention system, basic runoff analysis in test area has been carried out and runoff characteristics with size and locations of detention facilities has been simulated. The results of simulation are showing that alloted detention system can reduce the discharge of main stream and detention facilities' size and locations are major parameters of runoff reduction efficiency. It is concluded that alloted detention system can be a useful method in urban area's flood disaster mitigation and can secure safety against flood damages in urban areas.

• Journal of Power Electronics
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• v.12 no.2
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• pp.333-343
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• 2012

This paper proposes a strategy of flicker mitigation for doubly-fed induction generator (DFIG) wind turbine systems. In the weak grid system where the grid impedance ratio is low, the reactive power compensation only cannot suppress the flicker sufficiently due to the limited power capacity of the converters or the DFIG. For the full suppression of flickers, the active power smoothening using the energy storage system (ESS) needs to be utilized together with the reactive power compensation. The effectiveness of the proposed method is verified by PSCAD/EMTDC simulation results for a 2[MW] DFIG wind turbine system and by experimental results for a 3[kW] wind turbine simulator.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1102-1105
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• 1993

A fuzzy expert system for prediction and mitigation of sludge bulking was developed for an activated sludge process which treats waste water from a food industry. The developed system is able not only to infer the degree of progress of sludge bulking but also to generate remedial operation guides which may be sent to the local controllers as remote set points. One of the important consequences through this study is the BI (Bulking Index) inferred by the bulking prediction expert system was found to have a close correlation with the SVI (Sludge Volume Index) which is a practical measure of degree of bulking but needs tedious chores for its measurement.

• Smart Structures and Systems
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• v.7 no.5
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• pp.379-392
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• 2011

This paper presents a multi-functional system, consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) device, and its applications in stay cables. The proposed system is capable of offering multiple functions: (1) mitigating excessive vibrations of cables, (2) estimating cable tension, and (3) harvesting energy for wireless sensors used health monitoring of cable-stayed bridges. In the proposed system, the EMI device, consisting of permanent magnets and a solenoid coil, can converts vibration energy into electrical energy (i.e., induced emf); hence, it acts as an energy harvesting system. Moreover, the cable tension can be estimated by using the emf signals obtained from the EMI device. In addition, the MR damper, whose damping property is controlled by the harvested energy from the EMI device, can effectively reduce excessive cable vibrations. In this study, the multi-functionality of the proposed system is experimentally evaluated by conducting a shaking table test as well as a full-scale stay cable in a laboratory setting. In the shaking table experiment, the energy harvesting capability of the EMI device for wireless sensor nodes is investigated. The performance on the cable tension estimation and the vibration mitigation are evaluated using the full-scale cable test setup. The test results show that the proposed system can sufficiently generate and store the electricity for operating a wireless sensor node twice per day, significantly alleviate vibration of a stay cable (by providing about 20% larger damping compared to the passive optimal case), and estimate the cable tension accurately within a 2.5% error.

• Magazine of the Korean Society of Hazard Mitigation
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• v.7 no.4
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• pp.42-50
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• 2007

데이터에 입각한 과학적 안전관리시스템(Safety Management System, SMS)의 도입은 사후적 차원에 머물던 그간의 안전관리활동의 한계를 극복하고, 예방적 안전관리를 통하여 국가 항공안전증진에 획기적으로 기여할 것으로 기대된다. 이번 기고에서는 항공교통분야에 있어서 안전관리시스템(SMS)의 도입 현황과 함께 SMS의 핵심요소인 위험관리에 있어서, 평가된 위험이 시스템에서 정상적으로 관리되고 있는지 확인할 수 있는 안전평가(Safery Assessment) 개념에 대하여 국제민간항공기기(ICAO)에서 제시하는 개념들을 소개한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.77-80
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• 2006

Insensitive Munitions(IM) of solid propulsion system are defined as munitions that fulfil the performance and operational requirements, but will minimize the violence of a reaction when subjected to inadvertant stimuli. It should be clear that the reaction violence of rocket motor subjected to thermal stimuli can be mitigated by reducing confinement prior to propellant reaction. Devices designed to do this by venting the rocket motor case are commonly referred to as mitigation devices. The objective of this paper is to introduce the technical information related to the pyrotechnic mitigation devices for insensitive munition of solid rocket motor.