• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.3
• /
• pp.70-79
• /
• 2020

The main objective of this research to develop an IoT based wireless contactless ultrasonic system (ICUS) and its application to concrete structure. The developed system consists of 16 mems, 2Mhz digitizer, amplifying circuit, FPGA, and wifi module, enabling to measure leaky surface waves from concrete specimens without physical coupling process and wires. Multi-channel analysis is performed to improve the accuracy of data analysis, and the velocity of leaky surface waves and acoustics are derived. Field inspection of railroad concrete sleepers is conducted to evaluate the performance of the system and to compare the results with conventional ultrasonic pulse velocity (UPV). As a result of the field inspection, UPV was limited to evaluate damages. This is because crack pattern of railroad sleepers is parallel to ultrasonic ray path and accessibility of the railroad at the field is disadvantageous to contact-based UPV. On the other hand, ICUS possibly detect the damages as reduction of dynamic modulus by up to 59% compared to non-damaged specimen.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.1442-1444
• /
• 2004

현재 한국형 고속전철은 시운전 시험 중에 있으며, 차량 내에 상시 계측시스템이 구성되어 있어서 차량의 전기장치 신호나 기계장치 신호를 획득하여 주행 및 제동에 관한 성능 및 특성을 분석하고 파악할 수 있다. 하지만 차량의 안전성, 승객의 승차감 확보와 궤도의 빠른 유지보수를 위해 궤도를 전문적으로 감시하고 검측하는 시스템은 구축되어 있지 않다. 그러므로 고속전철 차량에 설치되어 고속주행 중에 궤도를 종합적이고 효율적으로 측정하는 전문적인 계측시스템을 구성할 필요가 있다. 따라서 궤도틀림의 검측방법과 검측기구 및 그 원리를 이해하고 선진국의 궤도 검측기술을 파악하여 보았다.

• Proceedings of the KIEE Conference
• /
• 2007.11a
• /
• pp.204-205
• /
• 2007

We have developed a new measurement system by using GPS to complement those errors. In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly-stable clock. The GPS mounted on the roof of TT4 in KHST receives a signal from the RS232 communication port, and it is connected to the network system in TT3 after converting with TCPIP communication. It is able to track the position of vehicle and synchronize the signal from different measurement system simultaneously. Therefore it is able to chase the fault occurrence, track inspection and electrical interruptionat real-time situation more accurately. There is not an error coursed by vehicle conditions such as slip and the slide.

• International Journal of Korean Welding Society
• /
• v.3 no.2
• /
• pp.53-59
• /
• 2003

Visual inspection using laser vision sensor was proposed for fast and economic inspection and was verified experimentally. Welding is one of the most important manufacturing processes for automotive and electronics industries as well as heavy industries. The weld zone influences the reliability of the products. There are two kinds of weld inspection tests, destructive and non­destructive test. Even though the destructive test is much more reliable, the product should be destroyed, and hence the non­destructive test such as ultrasonic or X­ray test was used to overcome this problem. However, these tests are not used for real time inspection.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.521-523
• /
• 1997

In this paper, We carried out investigation of monitoring algorithm development for electric car inspection and repair. For transmitting a data, reliable RS-422 is adopted. The LabWindows/CVI development tool of National Instruments Co. is used for the formation of monitoring screen. The experimental set-up is composed of a PC to PC system. It is applicable to electric car imspection and repair.

• Proceedings of the KSR Conference
• /
• 2005.05a
• /
• pp.211-219
• /
• 2005

The railway industry of each country has variant technical standards and regulations unlike other industries. For this reason, it is necessary to investigate the domestic technical standards and regulations and to prepare the countermeasure of the variance for advancing the korean high-speed railroad system into foreign market. This study was designed to investigate the railway design/manufacturing, examination/inspection and safety of domestic and foreign countries subject to a world market for advancing the korean high-speed railroad system into a foreign market. Because the reliance of a railroad system is a prerequisite for the safety of railroads, it is very important to obtain the reliance data, which is based on the RMS analysis of foreign countries subject to a world market.

• Proceedings of the Safety Management and Science Conference
• /
• 2009.11a
• /
• pp.461-470
• /
• 2009

A railroad has a benefit of the mass transportation of a passenger and cargo, but just a time of accident could cause a huge loss of a human life and property. Especially, a typhoon and a localized torrential downpour usually happened in summer season have caused average 38.29 times of the missing roadbed which support the railroad in recent 7 years. If a train would pass on this railroad which the roadbed was missed, there could be a huge accident and many people will die. But, the security issue is not satisfied because the method of sensing the missing roadbed is depending solely on the naked eye inspection by a person in charge. So, in this study, I would like to suggest the missing roadbed real-time sensing and train operation system to reduce the possibility of the railroad accident by controlling the operation of train when the missing roadbed condition would be sensed in the real-time system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.7
• /
• pp.3444-3449
• /
• 2013

The control module controlling points has become high-tech. but the introduction of relevant company's inspection intervals and methods, and the adoption of the way which is used in relay interlock system became the cause of a failure by excessive and incorrect maintenance. The Human error in failure recovery process can cause vital accidents including train derailment, the points monitoring system could prevent this problem by monitoring points' operation condition in real time. After conducting the changed inspection intervals that applied the results of the criticality of each failure type, MTBF, MTTR, availability, maintainer's opinion, the work became simplified, and, the failure did not occur for 4 consecutive years in contrast to the previous annual average of 11 failures.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.7
• /
• pp.1008-1012
• /
• 2014

Tunnel bracket is used in railway tunnel area in order to maintain insulation. Insulator performance evaluation test is proceeded refer to IEC 61109 but it is impossible to reflect all the field condition where insulator installed. Korea has clear four season in climatic condition and peninsula with lots of mountain in geomorphology condition. Tunnel bracket material which used in korea are butyl rubber, polymer and silicone. Most of them were installed without any internal climatic and geomorphology condition. According to the KORAIL operation data most of the insulator break down occurs in tunnel. So interval of inspection period is shorter then any other insulator and lots of maintenance cost incurs. Most major railway advanced country such as germany and japan maintain tunnel bracket with their own experience. For example visual inspection carried out with in one or two years and detailed inspection carried out between three to five years. This paper analyzed materials and shapes of tunnel bracket to in order to find optimized one in korea peninsula. Proposed bracket were tested under regulation and experience field data. Finally it was installed at the field and evaluated until now.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.6
• /
• pp.1103-1107
• /
• 2016

The automatic tensioning device of the catenary system constantly maintains the tension of the trolley wire by absorbing the variations due to the elasticity of the line caused by temperature variation. The tension plays an important role in affecting the electric motorcar operation directly. This paper suggests the methodology of the life cycle extension and the maintenance of the automatic tensioning device by means of performance diagnosis of the pulley type automatic tensioning device which has been commonly used for the electric railway system. Through conducting performance diagnosis and comparative test for the wornout pulley type automatic tensioning device by replacing the components such as the bearing and the bearing shaft without replacing all the assembly, the tensioning device is analyzed whether it is properly functioned. Provided that the maintenance regulation is reinforced so as to implement the bearing replacement through periodical precise inspection along with random check-up inspection which is now carried out by the operating organizations, it is ensured that the life cycle extension and the reduction of maintenance cost of the tensioning device could be achieved.