Point-type smoke sensors detect fire through sensor signals that are changed by smoke, which occurs early from the fire. However, the drawback of these smoke sensors is the drift of sensor signals due to the sensitivity to environmental changes. This can be the cause of occasional false alarms.

The first reason for sensor signal change in smoke sensors is seasonal changes in temperature and humidity. Secondly, in the case of an ionic smoke sensor, the accumulation of dust layers on the surface of radiation source decreases the ion current and the leakage of current between the electrodes causes the sensor signal to change. Inherent noise caused by the uncertainty of the radioactive decay for ionization is another reason, which is inversely proportional to the square root of the radioactivity. Lastly, the radiation sources used for the ionic smoke sensor are not uniform, so the sensitivities and signals of the sensors are also different, which also degrades the accuracy of fire alarm in a fire monitor based on a fixed threshold.

By these factors, sensor signals tend to increase or decrease slowly with time. If these signals are higher than a fixed threshold already set, the false alarm can be heard in the absence of fire, and if they are lower, they may generate the alarm late for real fires or may not generate the alarm at all. Therefore, smoke sensors or fire monitors need to adjust the threshold actively according to the sensor signals.

Jo Jin Song, a researcher at the Institute of Analysis, designed and verified a compensation algorithm that can automatically adjust the threshold for point-type smoke sensors or fire monitors.

The algorithm does not fix the threshold that is the criterion for identifying fire presence, but it can adjust it gradually to the change of sensor signals to improve the accuracy of alarm.

This algorithm can be applied to almost all point-type smoke sensors or fire monitors for active fire detection.

When the hull roof frame with a large bending radius is made with L-shaped steel instead of a square pipe by a press, the die must be designed correctly considering the spring-back in order to ensure high accuracy.

Ri Song Min, a researcher at the Faculty of Mechanical Science and Technology, proposed a method of selecting a reasonable bending radius of the die by considering the stress, strain characteristics and spring-back of work-pieces in the process of bending the L-shaped steel that is used in the manufacture of the roof frames of vehicles including underground trains by means of a press, and conducted a simulation analysis. In addition, by measuring the amount of spring-back at the time of bending with constant force using a press to compare the experimental values with simulation values, he evaluated the accuracy of the simulation analysis, and compared the bending radii of the die to form an L-shaped steel product for roof frames.

He performed a finite element analysis at the ceiling and the corner sections, respectively. The finite element simulation analysis result of the process of bending the L-shaped steel shows that the bending radius of the die must be designed to be 7 782mm and 426mm for the ceiling and the corner sections, respectively.

PTN (Packet Transport Network) based on MPLS-TP (Multi-Protocol Label Switching-Transport Profile) does not rely on subscriber service signals. It provides real-time transmission and robust OAM (Operation, Administration and Maintenance) functions thanks to VPN (Virtual Private Network) technique using LSP (Label Switch Path) and PW (Pseudo-Wire) for transparent transport, thus being widely used in transport systems for mobile communication.

The PTN for 3rd generation mobile communication is operated in the centralized way, and it is difficult to apply to the next generation mobile communication.

Kim Myong Jun, a researcher at the Faculty of Communication, has proposed a method of how to apply MPLS-TP based PTN device using dedicated network processor WINPATH to the next generation systems, and verified its application possibility.

The experimental results show that transport network for next generation can adopt MPLS-TP based PTN device by the proposed method.