• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.570-576
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• 2010

This paper can be used for GPS air navigation study on integrity monitoring algorithm as, the projected horizontal plane using GPS pseudorange residuals for fault detection satellites were suspected. Failure to remove the detected suspicious satellite, compare with threshold which is calculated using satellite deployment (PDOP) and determine whether the failure is presented. The theory that horizontal projection of the satellite failure residuals greater than residual of normal satellite is proved mathematically. Comparison with horizontal projection residuals are likely to malfunction in the satellite were presented. To evaluate the proposed algorithm, bias fault insert into GPS pseudorange, and compare with conventional parity space method about fault detection and isolation capability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2223-2229
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• 2010

The integrity monitoring of anomalous GPS signal have been researched because of the degradation of GPS satellite performance. It is known that anomalous GPS signal can occur by failure of GPS satellite, sudden increase of ionosphere delay error, SA, wrong modeling for navigation parameters from control segment, and an electromagnetic wave interference, etc. In case of GPS anomaly by satellites can arise from carrier frequency, code and navigation message. In this paper, the scenarios with navigation message errors were made by using GPS simulator, and the influences of GPS navigation message error to receiver were analysed. The anomalies of preamble, bits related TOW count message, subframe ID in HOW, bits related satellite healthy, and the other navigation message errors were described and simulated. Also, the number of satellites, DOP and pseudorange are analyzed to know how the anomalous signal can affect on GPS receiver.

• Environmental Engineering Research
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• v.11 no.5
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• pp.277-284
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• 2006

The genetic toxicity of environmental pollutants, namely, nonylphenol (NP), bisphenol A (BPA) and chloropyriphos (CP) was investigated in aquatic sentinel species, freshwater crustacean, Daphnia magna, and larva of aquatic midge, Chironomus tentans, using Comet assay. Physiological effect of such pollutants was also investigated by studying the specimens' rates of reproduction, growth and survival. Acute toxicity results showed that, as expected, Daphnia was more sensitive than Chironomus to chemical exposure. The order of acute toxicity was CP > NP > BPA in D. magna and NP > CP > BPA in C. tentans. BPA may exert a genotoxic effect on D. magna and C. tentans, given that DNA strand breaks increased in both species exposed to this compound, whereas NP- and CP-induced DNA damage occurred only in C. tentans. In vivo genotoxic data obtained in aquatic sentinel species could provide valuable information for freshwater quality monitoring. The experiments with NP-exposed D. magna showed that the pollutant has long-term effects on reproduction, whereas no short-term effect on DNA integrity was found, being an example of a false-negative result from the biomarkers perspective. This result could be interpreted that other mechanism than genetic alteration might be involved in NP-induced reproduction failure in D. magna. False-positive results from the genotoxic biomarker obtained in BPA-exposed D. magna and in NP-exposed C. tentans make it difficult to use DNA integrity as an early warning biomarker. However, as the mere presence of genotoxic compounds, which are potentially carcinogenic, is of high concern to human and ecosystem health, it could also be important to rapidly and effectively detect genotoxic compounds in the aquatic system in ways that do not necessarily accompany a higher level of alteration. Considering the potential of D. magna and C. tentans as bioindicator species, and the importance of genotoxic biomarkers in ecotoxicity monitoring, DNA damage in these species could provide useful information for environmental risk assessment.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.595-618
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• 2010

This paper describes the application of a wireless sensor network to a 31 meter-tall medieval tower located in the city of Trento, Italy. The effort is motivated by preservation of the integrity of a set of frescoes decorating the room on the second floor, representing one of most important International Gothic artworks in Europe. The specific application demanded development of customized hardware and software. The wireless module selected as the core platform allows reliable wireless communication at low cost with a long service life. Sensors include accelerometers, deformation gauges, and thermometers. A multi-hop data collection protocol was applied in the software to improve the system's flexibility and scalability. The system has been operating since September 2008, and in recent months the data loss ratio was estimated as less than 0.01%. The data acquired so far are in agreement with the prediction resulting a priori from the 3-dimensional FEM. Based on these data a Bayesian updating procedure is employed to real-time estimate the probability of abnormal condition states. This first period of operation demonstrated the stability and reliability of the system, and its ability to recognize any possible occurrence of abnormal conditions that could jeopardize the integrity of the frescos.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.402-408
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• 2021

GNSS-Reflectometry (GNSS-R) is a technique for measuring and analyzing signals transmitted from satellites, reflecting on the surface of land or sea. GNSS-R is mainly used for measuring the water level variation, typhoon and meteorological anomaly, soil moisture, and snow depth. This paper describes the concept and measurement principle of GNSS-R technology, especially focusing on the field of marine utilization and its feasibility. In particular, it presents the applications of this technique for monitoring the safety of marine environment as well as the marine vessel and their utilization areas based on currently available infrastructure on the ground and maritime reference stations, such as the existing differential GNSS reference stations and integrity monitors (DGNSS RSIM), and GNSS reference station infrastructure, using the ground-based and the satellite-based GNSS-R approaches.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.327-332
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• 2022

The Korea Augmentation Satellite System (KASS) is the Satellite-Based Augmentation System (SBAS) under development in Korea. KASS navigation service support navigation Safety of Life (SoL) service. KASS signal provides corrections to Global Positioning System (GPS) data received from KASS Reference Stations (KRS) and is broadcast form Geostationary Earth Orbiting (GEO) satellites to KASS users and is used by GPS/SBAS user equipment to improve the accuracy, availability, continuity and integrity of the navigation solution. Seven KRS's collect the satellite data and send them to the KASS Processing Stations (KPS) for the generation of the corrections and the monitoring the integrity. For performing its computation the KPS needs to know accurate and reliable KRS antennas coordinates. These coordinates are provided as configuration parameters to the KPS. This means that the reference frame in which the KPS work is the one represented by the set of coordinates provided as input. Therefore, the activity to maintain the accuracy of the KRS antenna coordinates is necessary, knowing that coordinates can evolve due to earth plates movements or earthquakes. In this paper, we analyzed the geodetic survey results for KRS antenna coordinates from Site Acceptance Test (SAT) #1 in December 2020 to August 2022. In the future, it is expected that these activities and planning for KRS coordinates maintenance will be produced and provided to KASS system operators for KPS configuration updates during the KASS lifetime of 15 years. Through these maintenance activities, it is expected that monitoring and analysis of unpredictable events such as earthquakes and seism will be possible in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.9
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• pp.3870-3884
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• 2020

The proposed framework of Four Layer Robust Storage in Cloud (FLRSC) architecture involves host server, local host and edge devices in addition to Virtual Machine Monitoring (VMM). The goal is to protect the privacy of stored data at edge devices. The computational intelligence (CI) part of our algorithm distributes blocks of data to three different layers by partially encoded and forwarded for decoding to the next layer using hash and greed Solomon algorithms. VMM monitoring uses snapshot algorithm to detect intrusion. The proposed system is compared with Tiang Wang method to validate efficiency of data transfer with security. Hence, security is proven against the indexed efficiency. It is an important study to integrate communication between local host software and nearer edge devices through different channels by verifying snapshot using lamport mechanism to ensure integrity and security at software level thereby reducing the latency. It also provides thorough knowledge and understanding about data communication at software level with VMM. The performance evaluation and feasibility study of security in FLRSC against three-layered approach is proven over 2³² blocks of data with 98% accuracy. Practical implications and contributions to the growing knowledge base are highlighted along with directions for further research.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.3
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• pp.278-286
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• 2011

The on-line monitoring for the wall thinning in secondary system has been considered one of main issues for the safety of nuclear power plants. To establish the on-line monitoring technique for the pipe wall thinning, the development of the ultrasonic transducer working in high-temperature is very important. In this investigation, the magnetostrictive transducer is concerned for high temperature condition up to $300^{\circ}C$. The magnetostrictive transducer has many advantages such as high working temperature, durability, cost-effectiveness, and shear waves, most of all. A thin Fe-Co alloy patch whose Curie temperature is over $900^{\circ}C$ was employed as a ferromagnetic material for magnetostriction. Wave transduction experiments in various temperature were carried out and the effect of bias magnets was considered together with the dry coupling performance of the transducer. From experimental results, consequently, it was found that the magnetostrictive transducer works stable even in high temperature up to $300^{\circ}C$ and can be a promising method for the on-line monitoring of the wall thinning in nuclear power plants.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.3
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• pp.268-279
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• 2007

The reliability of cold-bonding repair technique of carbon-fiber reinforced plastics (CFRP) laminates, often used as a temporary repair for the airplane maintenance, has been evaluated during cyclic loading and localized heating by nondestructive methods. Major concern was given to the evolution of damage after repair in the form of delaminations due to localized heating and cyclic loading combined. An area of interest both on the specimen repaired by cold-bonding and the specimen without repair where delaminations were induced by localized heating and cyclic loading was monitored by acoustic emission (AE) testing and further examined by pitch-catch low-frequency bond testing, and pulse-echo high-frequency ultrasonic testing. The results showed that the reliability of cold-bonding repair would be significantly reduced by the localized heating and cyclic loading combined rather than by the cyclic loading only. AE monitoring appeared to be an effective and reliable tool to monitor the integrity of temporarily repaired CFRP laminates in terms of the structural health monitoring (SHM) philosophy.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.6
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• pp.421-428
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• 2015

An important trend in the sustainment of military aircraft is the transition from preventative maintenance to condition based maintenance (CBM). For CBM, it is essential that the actual system condition can be measured and the measured condition can be reliably extrapolated to a convenient moment in the future in order to facilitate the planning process while maintaining flight safety. Much research effort is currently being made for the development of technologies that enable CBM, including structural health monitoring (SHM) systems. Great progress has already been made in sensors, sensor networks, data acquisition, models and algorithms, data fusion/mining techniques, etc. However, the transition of these technologies into service is very slow. This is because business cases are difficult to define and the certification of the SHM systems is very challenging. This paper describes a possibility for fielding a SHM system on legacy military aircraft with a minimum amount of certification issues and with a good prospect of a positive return on investment. For appropriate areas in the airframe the application of SHM will reconcile the fail-safety and slow crack growth damage tolerance approaches that can be used for safeguarding the continuing airworthiness of these areas, combining the benefits of both approaches and eliminating the drawbacks.