Yong Chil Seo

Gas-phase resistance to the vaporization of mercuric halides in high-temperature atmospheric gaseous condition

Gas-phase resistances to the vaporization of three mercury halides into atmosphere at elevated temperatures were evaluated. Lab-scale vaporization experiments for mercuric bromide, mercuric iodide and mercuric chloride were performed and the results were analyzed to evaluate gas-phase resistance to vaporization of three mercuric halides using the vaporization and condensation model. Overall mass transfer coefficients. KG for the sample mercuric halides, were in the range between 4.8× 106 and 1.6× 105 g-mole sec1 cm2 atm1 at the temperatures from the subliming to boiling temperatures and were much smaller than interfacial mass transfer coefficients, ki. It was estimated that resistance of pure gasphase mass transfer is much larger than that of the phase transition between condensed and gas phases. It could be therefore said that gas-phase mass transfer coefficients, kG for mercuric halides, were nearly equal to overall mass transfer coefficient, KG which could be determined as a function of temperatures.

Development of a Robotic System for Searching Human Victims in Disasters

This paper introduces a mobile robotic system being developed for urban search and rescue. In order to search human victims in narrow spaces, we developed two types of serially linked mobile robots, named KAEROT-Centipede and KAEROT-SnakeTV1, that can climb over large vertical steps or travel inside narrow vertical pipes. To send such mobile robots to the disaster areas coping with large obstacles, we also developed a assistant mobile robot, named KAEROT-QuadTrack, that has 4 articulated track modules. This paper describes the mechanical structure and control architecture of the serially linked mobile robots and the supporting configuration for torque reduction of the assistant mobile robot during spinning motion that usually requires large driving torque. The experimental results show that such robotic systems have good mobility over the various terrains in disaster areas.

Design of a heavy-duty manipulator for dismantling of a nuclear power plant

Some of the nuclear power plants in Korea have reached their end of life-cycle, and the importance of developing dismantling techniques has been emphasized. We designed a manipulator for decommissioning a reactor pressure vessel. We analyzed the work environment for disassembly and the workspace of the manipulator, and verified the validity of kinematic variables through a kinematic simulation. We verified through a dynamics simulation that each joint of the designed manipulator can be operated within the maximally allowed torque despite a load of 250 kg. Finally, we verified through the stress analysis that the manipulator is designed to secure at least two times higher safety factor.

A Measurement of Size of the Open Crack using Ultrasound Thermography

The dissipation of high-power ultrasonic energy at the faces of the defect causes an increase in temperature. It is resulted from localized selective heating in the vicinity of cracks because of the friction effect. In this paper the measurement of size and direction of crack using UET(Ultrasound Excitation Thermography) is described. The ultrasonic pulse energy is injected into the sample in one side. The hot spot, which is a small area around the crack tip and heated up highly, is observed. The hot spot, which is estimated as the starting point of the crack, is seen in the nearest position from the ultrasonic excitation point. Another ultrasonic pulse energy is injected into the sample in the opposite side. The hot spot, the ending point of the crack, is seen in the closest distance from the injection point also. From the calculation of the coordinates of both the first hot spot and the second hot spot observed, the size and slope of the crack is estimated. In the experiment of STS fatigue crack specimen(thickness 14mm), the size and the direction of the crack was measured.

Innovative Robot Technologies for Nuclear Power Plants Inspection and Maintenance

Nuclear energy has become the main energy source in Korea, but the safety issues are being debated since the Fukusima accident. In order to guarantee the safety and reliability of nuclear power plants, the uncertainty of human errors are being minimized by utilizing innovative technologies for inspection and maintenance. KAERI has developed robotic systems to upgrade and ensure the safety of nuclear facilities, to detect unusual conditions of facilities through remote inspection and to prevent human workers from high dose radiation with efficient plant maintenance.Copyright