• International Journal of Railway
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• v.2 no.3
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• pp.113-117
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• 2009

Risk management is an important part of system assurance and it is widely used in safety-related system. Railway signal system is one kind of safety-related system and its most important goal is to guarantee the safety of railway system. The method based on risk management can find and solve the security issues of railway signal system more effectively. This paper introduces the basic conception of risk management, studies the whole process of risk management and related tools and techniques and discusses some key points qualitatively combining with the particularity of railway signal system.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.317-319
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• 1993

The function estimation characteristics of neural networks can be used for sensor signal validation of a system. In case of applying the neural networks to signal validation, it is a important problem that the redundant sensor signals used as a input signal of neural networks should be validated. In this paper, we simplify the conventional parity space method in order to input the validated signal to the neural networks and also propose the sensor signal validation method, which estimates the reliable sensor output combining neural networks with the simplified parity space method. The acceptability of the proposed signal validation method is demonstrated by using the simulation data in safety injection accident of nuclear power plants.

• Journal of Positioning, Navigation, and Timing
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• v.2 no.1
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• pp.33-40
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• 2013

In this paper, GPS signal anomaly generation software is proposed which can be used for the analysis of GPS signal anomaly effect and the design, verification, and operation test of anomalous signal monitoring technique. For the implementation of anomalous signal generation technique, anomalous signals are generated using a commercial signal generation simulator, and their effects and characteristics are analyzed. An error model equation is proposed from the result of analysis, and the anomalous signal generation software is constructed based on this equation. The proposed anomalous signal generation software has high scalability so that users can easily utilize and apply, and is economical as the additional cost for purchasing equipment is not necessary. Also, it is capable of anomalous signal generation based on real-time signal by comparing with the commercial signal generation simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.9
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• pp.1583-1589
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• 2016

This paper proposes an improved spread spectrum time domain reflectometry (ISSTDR) using time-frequency correlation and reference signal elimination method in order to have more accurate fault determination and location detection than conventional (SSTDR) despite increased signal attenuation due to the long distance to cable fault location. The proposed method has a two-step process: the first step is to detect a peak location of the reference signal using time-frequency correlation analysis, and the second step is to detect a peak location of the correlation coefficient of the reflected signal by removing the reference signal. The proposed method was validated through comparison with existing SSTDR methods in open-and short-circuit fault detection experiments of low voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.7-14
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• 2008

One of purposes of installing signals at intersections is to protect traffic conflicts and accidents from occurring by means of arranging the right-of-way of travel more clearly. On the other hand, the installation of signals, and especially their location, can also have negative effects on safety. Therefore, the location of signals is of great importance. To secure a high safety level for urban signalized intersection, efforts are required to introduce a comprehensive recommendation or guideline for safety aspects of signal installation that takes local conditions into account. In this context, this reports on a study that analyzed the influence of signal location on the behavior of drivers who approach a signalized intersection in urban area. As a result, the study found out that the traffic signal location strongly affects the braking point of the Dilemma Zone(DZ), and the braking point of the DZ based on driving speed. Also, in terms of design layout, it has been illustrated that there is a close relation between signal location and road safety, especially DZ safety. Finally, this paper proposes a practical recommendation for signal installation related to how to locate the signal in practice for the sake of securing the safety level of signalized intersection.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.223-229
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• 1995

Loose Par Monitoring System(LPMS) is one of the fundamental diagnostic tools installed in the nuclear power plants. In this paper, recovery process algorithm and model for the corrupted impact signal generated by loose parts is presented. The characteristics of this algorithm can obtain a proper burst signal even though background noise is considerably high level comparing with actual impact signal. To verify performance of the proposed algorithm, we evaluate mathematically signal-to-noise ratio of primary output and noise. The performance of this recovery process algorithm is shown through computer simulation.

• Proceedings of the Safety Management and Science Conference
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• 2004.05a
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• pp.241-245
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• 2004

In this paper, we implement a portable bioelectric signal measurement system for the safety of industrial workers. The developed system consists of two parts: the one is boielectric signal measurement unit and the other is signal analyzer system with PDA. The former includes signal processing part, A/D convertor, and 8051 based microprocessor, the latter includes software for signal analysis and display. The developed system detects industrial worker's ECG and displays and stores it to PDA. The ECG data in PDA can be transmitted to PC located in a distance, allowing a doctor to review the ECG and make a treatment decision. A doctor analyzes the ECG data and gives medical treatment to industrial worker.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.68-75
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• 2019

As the tower crane accident emerged as a social issue in 2017, various government measures were prepared. Most of the measures are focused on erecting, climbing, and dismantling phases. Analyzes of 84 serious accidents related to tower cranes from 2000 to 2018 and 104 near misses accidents from 2016 to 2018 revealed that 50% of the serious accidents occurred during the operating phase. The main occupation influencing operating phase accidents was signalman(81.6% of serious accidents), whose communication and competency were governing causes. This result was the same in 294 questionnaires to signalmen. Signal systems and education policies for tower crane signalman in Korea and foreign countries were analyzed, and standardization of wireless signal system and improvement of education system were propose.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.47-55
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• 2017

As preliminary work for the establishment of a harmonized ship hand signal standard, this paper explores the availability of hand signals as a means of shipboard work communication and considers the validity of standardization. Prior to the feasibility study, shipboard work activities that use hand signals were classified based only on ship safety managers' arbitrary decisions. This survey was carried out to measure shipboard workers' willingness to communicate with hand signals and their preferences regarding the institutional standardization of a hand signal framework if they engage in activities classified as relevant. The results of statistical analysis (a t-test and correlation analysis) showed that respondents are willing to accept harmonized hand signals regardless of both their work type (crew/safety supervisors) and work department (deck/engine room) under working situations where hand signals are an available means of communication. In addition, there was a significant difference in the extent of shipboard workers' frequency of hand signal usages between each type of work activity, indicating a significant positive (+) correlation between frequency of usage and preference for standardization. Finally, it was concluded that shipboard work communication would be effectively improved if a follow-up study is carried out to establish prioritized harmonized hand signal standards for port-related work activities, such as crane operation, windlass/winch operation, line movement/delivery and cargo hold operations.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.3-8
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• 1997

This paper shows a performance estimation of windowing a single tone with added Gaussian noise and uniform noise. Signal-to-noise ratio can be determined by the ratio of the output noisy signal variance to the input noisy signal variance of a window. Standard deviation of noise is reduced by windowing Signal-to-noise ratio of the noisy signal is reduced by the windowing operation. Thus, performance of window function can be determined by this filtering operation that improved the signal-to-noise ratio.