• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.9
• /
• pp.760-770
• /
• 2012

In order to provide precision approach service based on GBAS, air navigation service providers should validate the GBAS system performance against international standard requirements and receive approval. The GBAS manufacturer should define integrity threat, analyze the integrity monitors and evaluate performance of the implemented monitors to verify integrity performance which is critical to the aircraft safety. This paper describes a statistical test result to evaluate performance of the code carrier divergence monitors implemented in KARI Integrity Monitor System software. The paper introduces analysis and test procedure which is developed for the performance evaluation and describes the analysis, the test scenario generation and the test results. The results show that the implemented monitors can detect the expected minimum detectable errors with satisfying the probability of missed detection requirements.

• Journal of Digital Convergence
• /
• v.14 no.4
• /
• pp.259-265
• /
• 2016

In this paper, a remote control system capable of monitoring and controlling the temperature of a refrigerator in real time using the ZigBee communication technology is developed. The developed system provides 24-hour surveillance function including temperature maintenance and it is able to determine monitored data from a remote location and to change the setting of the temperature value. In case the value is out of the setting, it is designed for administrators to verify the problem and take action, sending alarms to management server and the emergency to a preset administrator via SMS. Applying this system to refrigerators storing commercial, medical, and experimental material, the real time status such as temperature and malfunction of refrigerator can be managed up to 16 SZM(Slave Zigbee Module) by only one MZM(Master Zigbee Module).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.4
• /
• pp.1134-1147
• /
• 1998

Remote management and control system for LMDS wireless CATV network which is being developed at SK Telecom is developed. This system is composed of central control division located at head center and remote units for remote transceivers equipped in base stations and repeaters. It monitors the state of the remote transceivers and controls the operations using PSTN for iterface. Remote transceivers whould be equipped in pairs, and the operations are exchanged automatically in case of emergency situations. the remote units are designed not only to perform commands form central control division, bet to inform emergency situations such as disorder and power failure. This system works well, which is established at Central research center in SK Telecom with remote units such as BTX, PPTX, and PPRX. This system could be utilized in other applications requiring remote control through sligh modifications.

• Journal of the Korean Society for Railway
• /
• v.14 no.5
• /
• pp.416-424
• /
• 2011

The recent development of USN (Ubiquitous Sensor Network) technology has broadened its applications to many fields of industry. The USN technology enables the system to monitor and control the status of distributed sensor nodes based on the low-powered communications. Applying the USN in the train control domain, the operational efficiency can be enhanced, where the reliability and the safety of the system are the key challenges. This paper suggests the system design for evaluating and improving the reliability and safety of the gateway, which is a USN component that manages the radio network among the sensors and collects the information from them. For this purpose, the reliability and the level of safety integrity of a general gateway have been predicted quantitatively and the supplementary design has been proposed for the selected week points. The verification on the reliability and the safety of the improved gateway according to the related standards has been followed. With the results of the study, the applicability of USN gateway for train control systems has been reviewed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.5
• /
• pp.86-93
• /
• 2010

This paper presents the guideline for enhancing the reliability and availability of SAS with IEC 61850 based IEDs in real power system. The IEC 61850 standard communication networks and systems allow utilities to consider new designs for substations applicable both new substation and refurbishments. The existing solutions are based on hardwired interface between the primary substation equipment and the secondary protection, monitoring, control and recording devices. All over the world, lots of projects at different stages of realization have been reported during the last year leading to a rapid maturation of the associated technologies. At present, IEC 61850 is becoming a popular communication standard for the substation automation system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.2
• /
• pp.155-163
• /
• 2013

As the increasing HIF(High Impedance Fault) with the arc cannot be easily detected for the low fault current magnitude compared to actual load in distribution line. However, the arcing current shows that the magnitude varies with time and the signal is asymmetric. In addition, discontinuous changes occur at starting point of arc. Considering these characteristics, wavelet transformation of actual current data shows difference between before and after the fault. Althogh raw data(detail coefficient) of wavelet transform may not be directly applied to HIF detection logic in a device, there are several developing methods of HIF monitoring data using the original wavelet coefficients. In this paper, a simple and effective developing methods of HIF monitoring data were analized by using the signal data through an actual HIF experiment to apply them to economic devices. The methods using the sumation of the wavelet coefficient squares in one cycle of the fundamental frequency as the energies of the wavelet coefficeits and the sumation of the absolute values were compared. Besides, the improved method which less occupies H/W resouces and can be applied to field detection devices was proposed. and also Verification of this HIF detection method through field test on distribution system in KEPCO power testing center was performed.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.518-523
• /
• 2008

Using network communication, KTX OBCS is KTX's core device which inspects operation status of various electric equipments and supports driving command, train control, train's maintenance, train crew's driving. Since this device is manufactured as specialized system, being dependent on TGV manufacture specification and France's high speed train operation method, actual technic transfer is difficult. Therefore, there are many difficulties, since most of interface signals are connected with OBCS when function improvement, maintenance, various electric equipments(propulsion control device, auxiliary power supply device, door control device etc.) are replaced with localized ones, which are required in operational view after introduction of KTX. Ergo, this study would like to contribute to function improvement and maintenance's efficiency, furthermore to realize technical independence, escaping from dependency of developed foreign technology in high speed train and electric equipments, through KTX OBCS' function analysis and mutual interface information analysis with peripheral device(driver console, PID system, fault display device, various electric equipments).

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.54-57
• /
• 1998

As the physical layer on telecommunication network is replaced fiber optic lines, it is increased the need of systematic maintenance for fiber optic lines. Korea Telecom has developed FLOMS in order to establish maintenance processes for optical fiber lines. FLOMS has functions which manages optical facilities and tests optical fiber lines automatically. As a resuls, this system can check and/or report a fault. Operator, who is reponsible for management of optical fiber lines, can test the characteristics of optical fiber lines remotely using FLOMS. As interpoerable with Digital Transmission Management System, FLOMS provides efficient management for optical fiber lines. This system improves the work process to find fault location fast, detect the degradation of fiber quality, and make database of optical facilities efficiently.

• Journal of the Korean Institute of Gas
• /
• v.20 no.5
• /
• pp.57-63
• /
• 2016

Though a valve is a very important part in a system to control properly, it has potential failure caused by gap from valve stem to ball connection, and abrasion, crack, fixation causing operational trouble and accidents. 64% of the valve failure in the real case was the failure of airtightness and most accidents of leakage and explosion were occurred while fixing the failure. While there are no proper safety manual, maintenance procedure and regulation for industrial valves excluding safety valve, safety management for the valves is left to the discretion of the maintenance company. Strict maintenance that removes hazards and emergency response procedure are required to prevent and reduce the loss of accident. This study suggests safety enhancement measures through valve monitoring by investigating the status of use of valve and current maintenance. Enhancement of gas safety management can be acquired by a monitoring system that provides diagnosis for valve status, monitoring real-time gas leakage, management of entire cycle lifetime that can reduce maintenance cost.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.14 no.2
• /
• pp.122-131
• /
• 1994

Journal bearings in the rotating machineries are vulnerable to the contamination or the insufficient supply of lubricating oil, which is likely to be the cause of unexpected shutdown or malfunction of these systems. Various destructive and nondestructive testing methods had been used for the reduction of maintenance cost and the operational safety problems due to the accidents related to bearing damages. In this experimental approach, acoustic emission monitoring is employed to the detection of incipient failure caused by intervention of foreign particles most probable in the journal bearing systems. Experimental schedules for the intervention of foreign particles was composed to be more quantitative and systematic than last study in consideration of minimum oil film thickness and particle size. The experiment was conducted under such designed conditions as inserting alumina particles to the lubrication layer in the simulated journal bearing system. Several parameters such as AE rms level, waveform, AE energy distribution and other AE event parameters are used for analysis and characterization of damage source. The results showed that the history of damage was well correlated with the changes of AE rms level and the type of damage source signal can be verified using other informations such as waveform, distributions of AE parameters etc.