• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1690-1696
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• 2014

Network RTK generates spatial corrections by using differenced measurements from reference stations in the network, and the corrections are then provided to a rover. The rover, generally, uses linear interpolation, which assumes that the corrections at each reference station are spatially correlated, to obtain a precise correction of its location. However, an irregularity of the tropospheric delay is a real-world factor that violates this assumption. Tropospheric delay is a result of weather conditions, such as humidity, temperature and pressure, and it can cause spatial decorrelation when there are changes in the local climate. In this paper, we have defined the non-linear characteristics of the tropospheric delay between reference stations or user within a region as the "irregularity of tropospheric delay". Such an irregularity can negatively impact the network RTK performance. Therefore, we analyze the influence of the irregularity of tropospheric delay in network RTK based on meteorological data.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.7
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• pp.303-312
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• 2006

This paper proposes the architecture and protocol of a data communication network for the safety system in nuclear power plants. First, we establish four design criteria with respect to determinability, reliability, separation and isolation, and verification/validation. Next we construct the architecture of the safety network for the following systems: PPS (Plant Protection System), ESF-CCS (Engineered Safety Features-Component Control System) and CPCS (Core Protection Calculator System). The safety network consists of 12 sub-networks and takes the form of a hierarchical star. Among 163 communication nodes are about 1600 origin-destination (OD) pairs created on their traffic demands. The OD pairs are allowed to exchange data only during the pre-assigned time slots. Finally, the communication protocol is designed in consideration of design factors for the safety network. The design factors include a network topology of star, fiber-optic transmission media, synchronous data transfer mode, point-to-point link configuration, and a periodic transmission schedule etc. The resulting protocol is the modification of IEEE 802.15.4 (LR-WPAN) MAC combined with IEEE 802.3 (Fast Ethernet) PHY. The MAC layer of IEEE 802.15.4 is simplified by eliminating some unnecessary (unctions. Most importantly, the optional TDMA-like scheme called the guaranteed time slot (GTS) is changed to be mandatory to guarantee the periodic data transfer. The proposed protocol is formally specified using the SDL. By performing simulations and validations using Telelogic Tau SDL Suite, we find that the proposed safety protocol fits well with the characteristics and the requirements of the safety system in nuclear power plants.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.115-120
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• 2020

PS-LTE, which is mentioned as a next-generation disaster network technology, is a communication technology that supports communication between terminals and group communication necessary for public safety communication based on LTE technology. Currently, Korea is establishing a PS-LTE network construction plan and installing a PS-LTE system. The world is currently making a lot of efforts to build a disaster network system using PS-LTE. However, due to the characteristics of the closed network that only the related persons can access, it can not be operated like the existing commercial network, so it is necessary to build a new network. And it is expected that many periods and costs will be required. In order to establish a disaster safety communication network efficiently, it is necessary to consider the linkage of PS-LTE network, which is newly constructed by complementing the problems such as security and access priority to existing LTE network rather than unconditional new construction.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.3
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• pp.88-93
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• 2015

Among other various aspects of safety culture, this research has considered safety culture from the view of aviation. A tool to examine aviation safety culture has been developed on the basis of Global Aviation Safety Network's safety culture survey. Using this tool, the degree of perception of Korean national carriers' pilots in safety culture has been examined three times for the period from 2002 to 2015. Compared to an initial result of the survey in 2002, results in 2008 and 2015 demonstrate that safety culture among pilots has rapidly changed from negative and bureaucratic to positive. Hence, it is expected that positive index of safety culture will increase 28% (total approximate 90%) in 2020.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2225-2234
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• 2011

According to Railway Safety Act, Korea Transportation Safety Authority (KOTSA) has been entrusted with 'Integrated Railway Safety Audit (IRSA) and has implemented the safety audit to the Railway operation agencies such as Korea Railway (KORAIL) and the Railway facility management organization such as the Korea Rail Network Authority (KR Network). The target of IRSA is to establish the effective rail safety management system and to raise the safety level of the Railway operation and facility agencies by checking synthetically their performance of safety duties with sincerity according to the Railway Safety Act. Even though newly introduced IRSA is conducted smoothly, it is necessary to study the methodology and criteria of the state's safety audit system. The purpose of this paper is to improve the efficiency of IRSA by the comparative research between IRSA and other similar safety audit system and to establish the consecutive improvement concept of IRSA. Second purpose is to confirm the effectiveness of IRSA by the analysis of the relationship between audit results and the safety level of the rail operation agencies.

• Journal of the Korea Safety Management & Science
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• v.15 no.2
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• pp.161-166
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• 2013

The purpose of this research is to analyse the research subject in journal of Korean safety management and sciences. Total 1850 key words in 560 papers were analysed by the Pajek system which is one of well known social network analysis tool. Key words trend from 2008 to 2012 was examined. Then the relationship among each key words was visualized. There were five key words group which strongly connected among key words. The degree centrality, between centrality, proximity prestige on each key words were calculated to verify influence degree to other key words.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.8
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• pp.393-400
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• 2016

Recently, there have been various researches on efficient and automatic analysis on urban environment methods that utilize the computer vision and machine learning technology. Among many new analyses, urban safety analysis has received a major attention. In order to predict more accurately on safety score and reflect the human visual perception, it is necessary to consider the generic and local information that are most important to human perception. In this paper, we use Double-column Convolutional Neural network consisting of generic and local columns for the prediction of urban safety. The input of generic and local column used re-sized and random cropped images from original images, respectively. In addition, a new learning method is proposed to solve the problem of over-fitting in a particular column in the learning process. For the performance comparison of our Double-column Convolutional Neural Network, we compare two Support Vector Regression and three Convolutional Neural Network models using Root Mean Square Error and correlation analysis. Our experimental results demonstrate that our Double-column Convolutional Neural Network model show the best performance with Root Mean Square Error of 0.7432 and Pearson/Spearman correlation coefficient of 0.853/0.840.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.117-129
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• 2009

This paper studied the safety management network system of infrastructure which constructed smart sensors, closed-circuit television(CCTV) and monitoring system. This safety management of infrastructure applied to bridge, cut slop and tunnel, embankment etc. The system applied to technologies of standardization guidelines, data acquirement technologies, data analysis and judgment technologies, system integration setup technology, and IT technologies. It was constructed safety management network system of various infrastructure to improve efficient management and operation for many infrastructure. Integrated safety management network system of infrastructure consisted of the real-time structural health monitoring system of each infrastructure, integrated control center, measured data transmission using i of tet web-based, collecting data using sf ver, early alarm system which the dangerous event of infrastructure occurred. Integrated control center consisted of conference room, control room to manage and analysis the data, server room to present the measured data and to collect the raw data. Early alarm system proposed realization of warning and response within 5 minute or less through development of sensor-based progress report and propagation automation system using the media such as MMS, VMS, EMS, FMS, SMS and web services of report and propagation. Based on this, the most effective u-Infrastructure Safety Management System is expected to be stably established at a less cost, thus making people's life more comfortable. Information obtained from such systems could be useful for maintenance or structural safety evaluation of existing structures, rapid evaluation of conditions of damaged structures after an earthquake, estimation of residual life of structures, repair and retrofitting of structures, maintenance, management or rehabilitation of historical structures.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.63-68
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• 2008

The ubiquitous technology is capable of innovating various area to constructing intelligent and network to all objects. This technology can construct network infrastructure to facilities for applying legacy industry and need to develop intelligent service that analyze context-aware through network. This paper derive and propose the introduction range of ubiquitous technology, which should be testified and analyzed network, and studied the detection and analysis of information for managing gas facilities. We investigate the current status of gas facilities and automatic reading system, testing and analyzing wireless personal area network and mobile communication by scalability, self-configuration, connection in underground. Furthermore, we propose modelization method for intelligent service and derive the introduction range for applying ubiquitous technologies for managing gas facilities.

• Journal of the Korean Society of Safety
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• v.12 no.1
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• pp.129-132
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• 1997

The effectiveness of an ensuring the facility safety depends on the ability to find abnormal part(s) and remove that part(s). This requires the knowledge of that machine and ability to recover that machine. In this paper, it is discribed how to design the fuzzy based self organizing neural network expert system in order to find syptom source(s).