• Korean Security Journal
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• no.55
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• pp.31-55
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• 2018

The purpose of this study is to analyze the precedence analysis of traffic safety facilities installation for traffic accidents. The main results were as follows. First, the precedence of the number of traffic safety signs installation for the number of traffic accident is follows. The number of traffic safety signs[total number] (time precedent 1), the number of traffic safety signs[attention] (time precedent 7), the number of traffic safety signs[regulation] (time precedent 7), the number of traffic safety signs[indication] (time precedent 4) precede the number of traffic accidents as negative(-) relationship. Second, the number of traffic signal equipments[pedestrian lamp] (time precedent 2) precedes the number of traffic accidents as negative(-) relationship. Third, the precedence of the increase/decrease rate of traffic safety facilities installation for the increase/decrease rate of traffic accident is follows. The increase/decrease rate of traffic safety signs[total number] (time precedent 1), the increase/decrease rate of traffic safety signs[attention] (time precedent 1), the increase/decrease rate of traffic safety signs[indication] (time precedent 1), the increase/decrease rate of traffic safety signs[auxiliary] (time precedent 1) precede the increase/decrease rate of traffic accidents as negative(-) relationship. Fourth, the increase/decrease rate of traffic signal equipments[pedestrian lamp] (time precedent 0) accompanies the increase/decrease rate of traffic accidents as positive (+) relationship.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.1-6
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• 2019

This study relates to acquiring biological signal without attaching directly to the user using UWB(Ultra Wide Band) radar. The collected information is the respiratory rate, heart rate, and the degree of movement during sleep, and this information is used to measure the sleep state. A breathing measurement algorithm and a sleep state detection algorithm were developed to graph the measured data. Information about the sleep state will be used as a personalized diagnosis by connecting with the medical institution and contribute to the prevention of sleep related diseases. In addition, biological signal will be linked to various sensors in the era of the 4th industrial revolution, leading to smart healthcare, which will make human life more enriching.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.473-480
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• 2002

In this paper, it was proposed that hazard analysis and risk assessment about railway signal systems using FTA(Fault Tree Analysis) and ETA(Event Tree Analysis) one of the reliability analysis methods executed and output value based on the hazard baseline of CENELEC and EC 61508 producted, and also the SIL(Safety Integrity Level)/THR(Tolerable Hazard Rate) about the system set. On the basis of this principle, more systematic standardizations are required to operate railway system and in the future, we hope that safety and reliability of signal equipment will be better improved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.37-40
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• 2002

Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in cable TV.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.2
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• pp.70-75
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• 2014

A track circuit is a critical piece of equipment that allows the existence of the trains on the track to be detected. Train detection is very important for the signal safety equipment. It allows for the confirmation of a train's location, the locking of switch points, the coordination of safe distance between trains, and the advance notice of a train's arrival. Track circuits can be powered by AC or DC. The DC track circuits are usually used on non-electrified tracks. On these tracks, many signal errors can be caused by lightning or problems with the power source. These problems can also cause damages to the rectifiers which must be repaired or replaced, promptly. This issue is especially problematic in the summer because of the higher frequency of thunderstorms. Issues with track circuits also cause problems for other equipment, such as railroad crossings and switch points. This further disrupts the safe operation of trains. This study aims to enhance maintenance efficiency and improve safety by utilizing parallel operation and multiplexing of a DC track circuit as well as installing an external surge protector. The experimental results on the operation of the proposed method is also presented.

• Current Optics and Photonics
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• v.2 no.1
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• pp.7-14
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• 2018

As a sophisticated detection technology, LIDAR has been widely employed to probe low-altitude windshear. Due to the drawbacks of the traditional ramp algorithm, the alarm accuracy of the LIDAR has not been satisfactory. Aiming at settling this matter, a novel method is proposed on the basis of improved signal smoothing and second windshear detection, which essentially acts as a combination of ramp algorithm and segmentation approach, involving the human factor as well as signal fluctuations. Experiments on the real and artificial signals verify our approach.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.48-53
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• 2012

This paper is purposed to develop portable electric instrument to select NI-9223(National instrument comp.) and clamp meter(HIOKI comp.), which can be used in developing electric instrument, to detect leakage current(ZCT) and current(CT) signals. In this paper, The electric instrument that can interface with current and leakage current instrument(HIOKI 9283), is developed by NI-9223 of NI comp.. HIOKI clamp meter can measure current signals certainly by high-sensitivity of 10 ${\mu}A$ resolution(leakage current : at 10 mA range) and current 1~200A range. The NI-9223 use four 16-bit analog-to-digital converters(ADCs) for true simultaneous sampling at up to 1 MS/s per channel. NI-9223 can synchronize all analog input modules installed in the same chassis to share the same start clock and/or sample clocks. The monitoring program is developed by SignalExpress of LabVIEW. The monitoring program are developed to analyze at simultaneous sampling on electrical signals such as leakage current(ZCT) and current(CT). The developed system verification tests were conducted, and portable electric instrument can be used in place which requires analysis of the actual electrical signal.

• Journal of the Korean Society of Safety
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• v.31 no.3
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• pp.28-33
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• 2016

Since defects in the wheels of railway vehicles, which occur due to wears with the rail, cause serious damage to the running device, the diagnostic monitoring system for condition-based maintenance is required to secure the driving safety. In this paper, we studied to apply a useful Cepstrum analysis to detect periodic structure in spectrum among the vibration signal processing techniques for the fault diagnosis of a rotating body such as wheel. In order to analyze in variations of train velocity, the Cepstrum analysis was performed after a domain change of the vibration signal from time domain to rotation angle domain. When domains change, it is important to use a interpolation for a uniform interval of the rotation angle. Finally, the Cepstrum analysis for wheel flat detection was verified by using the vibration signal including the disturbance resulting from the rail irregularities and the vibration of bogie components.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.3
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• pp.229-234
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• 2021

In this paper, a study was conducted on the power amplifier control required to design an eLoran transmitter system using a low-height antenna. The eLoran transmitter developed during the eLoran technology development project conducted in Korea used a small 35 m antenna due to the difficulty of securing a site for antenna installation. This antenna height is very low compared to the height of 750 m which is required for eLoran 100 kHz signal transmission without any radiation loss. In the case of using such a small antenna, not only the radiation efficiency of the transmission is lowered, but also the power module control must be performed more precisely in order to transmit the eLoran standard signal. The equivalent RLC circuit of the transmitter system was implemented and transient analysis was conducted to derive the input required voltage for satisfying the output requirement. The voltage waveform was also generated by the RLC circuit analysis to generate the eLoran signal. Furthermore, we suggest power width modulation method to control eLoran power amplifier module more sophisticatedly.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.2
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• pp.153-158
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• 2021

In order to mitigate the vulnerability of the satellite navigation system against radio frequency interference, South Korea has been developing advanced terrestrial navigation system (eLoran) technology since 2016. The eLoran system synchronizes the transmission time of the pulse used in the existing Loran-C system with UTC and transmits correction information that can improve the position error. The eLoran system is known to reduce the position error of about 460 m of the existing Loran-C system to 20 m, and for this, the transmitter must be able to transmit eLoran signals according to more stringent standards. For this reason, an international standard that further developed the Loran-C signal standard established by US Coast Guard was established by Society of Automotive Engineers (SAE) International. In this paper, based on the analysis of the SAE9990 document, the international standard for eLoran transmission signals, a standard inspection process was produced to check whether the eLoran transmitter is transmitting signals in accordance with the standard.