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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Safety
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Journal DOI :
The Korean Society Safety
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Volume & Issues
Volume 5, Issue 2 - Dec 2006
Volume 5, Issue 1 - Jun 2006
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Measurement and Analysis of Current Collection Signals in Korean High-speed Railway
Kim, Jung-Soo ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 1~5
A data acquisition and processing system for measuring the current collection signals of the Korean High-speed Railway is developed. The current collection system is composed of a pantograph and the overhead catenary that supplies electrical power to the train through the pantograph. The system simultaneously measures the signals generated at the interface between the catenary and the pantograph through the accelerometers, load cells and strain gauges placed at various locations. The on-track test data are processed to evaluate the current collection reliability. The fiequency analysis of the signals reveals the presence of several structural vibration modes in the pantograph, as well as the components arising from the periodicity in the structure of the catenary and pantograph at the interface. The feasibility of predicting the contact performance from the measured signals is also demonstrated.
Predictive and Preventive Maintenance using Distributed Control on LonWorks/IP Network
Song, Ki-Won ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 6~11
The time delay in servo control on LonWorks/IP Virtual Device Network (VDN) is highly stochastic in nature. LonWorks/IP VDN induced time delay deteriorates the performance and stability of the real-time distributed control system and hinders an effective preventive and predictive maintenance. Especially in real-time distributed servo applications on the factory floor, timely response is essential for predictive and preventive maintenance. In order to guarantee the stability and performance of the system for effective preventive and predictive maintenance, LonWorks/IP VDN induced time delay needs to be predicted and compensated for. In this paper position control simulation of DC servo motor using Zero Phase Error Tracking Controller (ZPETC) as a feedforward controller, and Internal Model Controllers (IMC) based on Smith predictor with disturbance observer as a feedback controller is performed. The validity of the proposed control scheme is demonstrated by comparing the IMC based on Smith predictor with disturbance observer.
Safety Assessment in Operation of Human-centered Robots - An Information-theoretic Approach
Choi, Gi-Heung ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 12~17
Operations of human-centered robot, in general, facilitates the creation of new process that may potentially harm the human operators. Design of safety-guaranteed operation of human-centered robots is, therefore, important since it determines the ultimate outcomes of operations involving safety of human operators. This study discusses the application of information-theoretic measures to safety assessment of human-centered robotic operations. Some examples are given.
Performance Evaluation of Early Streamer Emission Lightning Air Terminal
Choi, Sang-Won ; Her, Yong ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 18~23
Studies have claimed that ESE (Early Streamer Emission) air terminals offer a vastly increased zone of protection over that of traditional lightning rods (Franklin rods) by causing the emission of an upward streamer/leader: The upward streamer/leader will propagate towards the tip of the downward leader at an early stage in the attachment process.. This paper shows the results of a performance evaluation test of a particular type of the ESE air terminal (called "ElecHippo") with a simple rod tested at the Korea Electrotechnology Research Institute (KERI). The corona emission current of the ElecHippo made by Yong-Jin Enterprise Corp. has also been measured at the Occupational Safety & Health Research Institute (OSHRI). The results show that the ElecHippo meets the French standard of NFC 17-102-1995. The results also verify the ESE performance by measuring the ion emission current generated in the discharge electrode gap as a function of the capacitance and inductance of the equipped devices. Finally, we propose a new method for grounding the system to reduce the lightning damage by combining the ESE air terminal, the early discharge earth plate, the lightning strike recorder and the surge protection device.
An Experimental Study on Resisting Force of Scaffolding Frames using Buckled Pipe
Na, Young-Chan ; Son, Ki-Sang ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 24~28
There are many structural problems when the scaffolding frame is applied to a construction site contractor may use a used pipe or buckled pipe which they lended them from commercial firms without any inspection of those materials even though they have been used and exposed to weather for a long times. Therefore, they should be checked of their current capacity, comparing with the original one so that construction contractor can apply their capacity to a temporary frame depending on the site situation against collapsion of those. This study is mainly focused on the behavior of a scaffolding frame using prebuckled pipes. Additionally, standard frame with bracing and without bracing case are also tested for comparing with the prebuckled case. Prebuckled case has its capacity less approximately 20 % than the standard frame.
A Flow Analysis of a Refrigeration Warehouse where an Unusual Death of an Operator Occurred by Deficiency of Oxygen
Park, Chan-Seong ; Moon, Jung-Eun ; Kim, Yoon-Ho ; Kim, Jin-Pyo ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 29~33
A numerical flow analysis of the case of a refrigeration warehouse where an unusual death of an operator occurred by deficiency of oxygen is performed by using STAR-CD program of the computational fluid dynamics (CFD) code. The refrigeration room of the warehouse for storing the fruits maintains an atmosphere of 95% nitrogen and 5% oxygen by volume. When the operator was found dead in the refrigeration room, the room was in normal operating conditions except for the fact that the auxiliary door had been left open. For the flow analysis, unsteady 3-dimensional natural convection with mass transfer is considered. The flow analysis result is compared with the oxygen concentration level measured against time during on-site investigation. The change in oxygen concentration level in the warehouse due to the opening of the auxiliary door is found to be negligible.
Generation of Effective Cutting Conditions for Machining Safety in a Manufacturing Industry
Seo, Ji-Han ; Park, Byoung-Tae ;
International Journal of Safety, volume 5, issue 2, 2006, Pages 34~37
As part of an effort to systematize the operation planning for cutting processes, the neural network method has been applied to model the process of selecting cutting conditions and subsequently to arrive at effective and safe cutting conditions through learning during training of the model. New cutting conditions that are more effective and safer for the given circumstance are obtained. The proposed algorithm deletes the old information previously learned, and then makes the network make at improvement by learning. As a result, the new algorithm provides useful cutting conditions for safer manufacturing environments. A variety of simulation cases illustrate the performance of the proposed methodology. The simulation results are provided and discussed.