• Ocean and Polar Research
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• v.29 no.4
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• pp.339-348
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• 2007

In this work, we compared the characteristics of three benthic biotic indices (BPI, AMBI, BIBI) which indicates the health condition of benthic communities in Masan Bay, Korea where anthropogenic impacts have been concentrated. Also we evaluated the usefulness of these benthic indices and some problems if they were applied to the Korean coastal waters. For this we used the macrozoobenthos data collected using van Veen grab ($0.1\;m^2$) at 21 sites in Masan Bay in February and August 2004. Based on the BPI values, two stations in the inner bay were found in a very hard polluted condition and three stations in the middle bay were also in a highly polluted condition. Only one station located in the bay mouth was in a normal condition. The inner bay stations showed very high AMBI values (${\geq}5.0$), indicating a highly polluted condition. The bay mouth station was assessed in a moderately polluted condition. The overall BIBI values in Masan Bay were in the range between 1.0 and 3.0. The inner bay stations showed low BIBI values (${\leq}2.0$) in the severely degraded condition. The bay mouth station with high BIBI value over 3.0 was assessed as a normal condition. All three benthos indices showed that macrozoobenthic communities in the inner bay were in a seriously polluted condition all year round, and macrobenthic faunas in the bay mouth seemed in a bad healthy condition (slightly polluted) based on AMBI during summer season. These three benthic biotic indices showed the similar assessment result, and thus we consider that each of them is a useful tool for the assessment of coastal benthic ecosystems under the organic enrichment in sediment.

• Journal of Advanced Navigation Technology
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• v.28 no.1
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• pp.1-14
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• 2024

Global navigation satellite system (GNSS) providing position, navigation and timing (PNT) services consist of satellite, ground, and user systems. Monitoring stations, a key element of the ground segment, play a crucial role in continuously collecting satellite navigation signals for service provision and fault detection. These stations detect anomalies such as threats to the signal-in-space (SIS) of satellites, receiver issues, and local threats. They deliver received data and detection results to the master station. This paper introduces the main monitoring algorithms and measurement pre-processing processes for quality assessment and fault detection of received satellite signals in current satellite navigation system monitoring stations. Furthermore, it proposes a strategy for the development of components, architecture, and algorithms for the new regional navigation satellite system (RNSS) monitoring stations.

• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.601-613
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• 2011

This study is focused on a climate data integrity to improve water quality assessment due to the social development projects. The study is in an attempt to calculate both extreme ranges of weather data measurements and partly provide means to assess qualification of data which fall within the extremes at the 23 meteorological weather stations. Generally speaking, maximum temperature, minimum temperature, relative humidity, dew point temperature are in the range of reasonable accuracy. However, there found some outliers of the brightness sunshine hours in Cheonan station. Also some years in Gwangju, Seoul, Wonju, Busan, and Jeju never reach to their upper limit and perhaps the calibration of the equipment is doubtful. The users need to take cautions in using the brightness sunshine hour data in preparation of water resources planning and management by estimating evapotranspiration and river discharge, and/or growth rate of the algae (phytoplankton).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4C
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• pp.290-296
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• 2012

In this paper, we propose a practical authentication system based on Wireless Body Area Networks(WBAN) for U-healthcare medical information environments. The proposed authentication system is based on symmetric cryptosystem such as AES and is designed to not only provide security such as data secrecy, data authentication, data integrity, but also prevent replay attack by adopting timestamp technique and perform secure authentication between sensor node, master node, base-station, and medical server.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1190-1197
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• 2006

We have evaluated the structural stability of a platform screen door due to train wind pressure. The platform screen door was installed at the ground and underground station and had 65 meters in length. Also, the platform screen door was a safety device because it was placed between the train and the platform. The finite element analysis was used to calculate the stresses and deflections of platform screen door caused by wind pressure using ANSYS 10.0. Quasi-static analysis was introduced to save calculating time and check quickly structural performances when compared to those of transient analysis. The results show that structural stability of the platform screen door under train wind pressure is proven and quasi-static analysis can quickly check the structural integrity of platform screen door.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.93-96
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• 2022

The boiler tubes of thermal power plants are exposed to harsh environment of high temperature and high pressure, and the deterioration state of materials rapidly increases. In particular, parent material and welds of the materials used are subjected to a temperature change and various constraints, resulting in deformation and its growth, resulting in frequent leakage accidents caused by tube failure. The power plant checks the integrity of boiler tubes through non-destructive testing as it may act as huge costs loss and limitation of power supply during power station shutdown period due to boiler tube leakage. However, the current non-destructive testing is extremely limited in the field to detect micro cracks. In this study, the ability of metal magnetic memory technique to detect flaws of size that are difficult to inspect by the visual or general non-destructive methods was verified in the early stage of their occurrence.

• Journal of the Society of Disaster Information
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• v.13 no.2
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• pp.267-275
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• 2017

This research is about the development of e-forensic tool that extract & analyze different forms of digital evidence that individuals come across in a disaster scene. The tool utilizes digital forensic techniques which makes the tool efficient in any disaster analysis situation. In order for the forensic evidence to be selected as legal evidence, the evidence needs to be proven that it is in its original state with no forgery involved. This is where the e-forensic tool comes in, as its ability to collect digital evidence during investigation has proven; that the tool can keep the evidence in its original state and increase the integrity by generating hash TAG and adding the forensic evidence to a password encoded file.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1619-1625
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• 2017

Civil global navigation satellite system (GNSS) does not meet user performance requirements for specific PNT (Positioning, Navigation, and Time) applications. Therefore, various differential systems are used to augment GNSS for improving positioning accuracy and integrity. The MTSAT satellite augmentation system (MSAS) is the Japanese satellite based augmentation system. This paper is for analyzing the characteristics of Japanese MSAS in Korean peninsula. First of all, it was done for analyzing not only DGNSS navigation signal but also the navigation parameter through simulation and experimental tests. As a result of data analyses, the sufficient navigation satellites to determine 3-D position based on DGNSS are simultaneously available at MSAS monitering station and the southern region of Korean peninsula. It was verified that the carrier to noise signals are stable to maintain the reliable 3-D position and that the level of 2m (2drms) accuracy is very similar to the ordinary worldwide DGNSS as well.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.2
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• pp.79-85
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• 2019

The mission tasks of polar exploration utilizing unmanned systems such as glacier monitoring, ecosystem research, and inland exploration have been expanded. To facilitate unmanned exploration mission tasks, precise and robust navigation systems are required. However, limitations on the utilization of satellite navigation system are present due to satellite orbital characteristics at the polar region located in a high latitude. The orbital inclination of global positioning system (GPS), which was developed to be utilized in mid-latitude sites, was designed at $55^{\circ}$. This means that as the user is located in higher latitudes, the satellite visibility and vertical precision become worse. In addition, the use of satellite-based wide-area augmentation system (SBAS) is also limited in higher latitude regions than the maximum latitude of signal reception by stationary satellites, which is $70^{\circ}$. This study proposes a local-area augmentation system that additionally utilizes Global Navigation Satellite System (GLONASS) considering satellite navigation system environment in Polar Regions. The orbital inclination of GLONASS is $64.8^{\circ}$, which is suitable in order to ensure satellite visibility in high-latitude regions. In contrast, GLONASS has different system operation elements such as configuration elements of navigation message and update cycle and has a statistically different signal error level around 4 m, which is larger than that of GPS. Thus, such system characteristics must be taken into consideration to ensure data integrity and monitor GLONASS signal fault. This study took GLONASS system characteristics and performance into consideration to improve previously developed fault detection algorithm in the local-area augmentation system based on GPS. In addition, real GNSS observation data were acquired from the receivers installed at the Antarctic King Sejong Station to analyze positioning accuracy and calculate test statistics of the fault monitors. Finally, this study analyzed the satellite visibility of GPS/GLONASS-based local-area augmentation system in Polar Regions and conducted performance evaluations through simulations.

• 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.