• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.612-617
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• 2000

This paper describes the experience gained from the treatments for prevention of blade failure occurred in the low-pressure turbine. Some cracks due to high cycle fatigue were found at the blades in low-pressure turbines after long time operation. Such failure was mainly caused by the resonance of the blade with the vane passing frequency excitation. If a natural frequency of the blade exists near the excitation frequency, a resonant vibration can occur and leads to a large amount of stress which may cause fatigue failures in turbine blades. To avoid the resonance of the blade, some modifications have been performed and full-scaled mockup testing has been done to confirm the verification for modification. Test result shows that enlarging the span cover is very useful to change the natural frequency of the grouped blades effectively.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.451-456
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• 1997

Temperature distribution measurements in the mockup apparatus of reactor vessel were performed to determine the effective thermal conductivity of porous media with different geometry and to obtain the experimental data for the heat transfer processes by natural convection occurring in the air duct. The temperature distributions at four separated sections with different arrangements of porous media have different slopes according to the geometrical configuration. From the measured temperature distribution, effective thermal conductivity have been derived using the least square fitting method. The test at air duct was performed to the high heat removal at 3.4kW/$m^2$ by the natural convection from the outer wall to the air. And also the temperature distributions in the air duct agree well with the 1/7th power-law turbulent temperature distribution. The obtained heat transfer data have been compared with the Shin's and Sieger's correlations.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.60-65
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• 2015

This study is to explore floor impact sound and sound insulation of reinforced concrete structure with void-deck slab system which combines polystyrene void foam and T-shaped steel deck plate. A void-deck slab system can effectively reduce the amount of concrete used and hence the mass of a reinforced concrete slab. Also void slab system has dynamically favorable for bending. Three-bay 2-story building was constructed as a mock up test specimen using void-deck slab system and floor impact sound was measured to valuate sound insulation performance. Light weight floor impact and heavy weight floor impact were investigated. Light weight floor impact pressure levels were 32dB, 28dB, and 29db at representative locations which are $1^{st}$ level in the floor impact sound insulation performance grading system. The heavy-weight floor impact pressure levels were 44dB, 45dB, and 43dB at representative locations which are $2^{nd}$ level in the floor impact sound insulation performance grading system. Therefore void-deck slab system can be used in public housing apartment building in terms of not only effectively reduced construction materials but also floor impact sound insulation.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2226-2230
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• 2005

The Advanced Spent Fuel Conditioning Process (ACP), which is a pre-disposal treatment process for spent fuel is being developed at the Korea Atomic Energy Research Institute (KAERI). The ACP equipment is operated in an intense radiation field as well as in a high temperature. Thus, the equipment is designed in consideration of the remote handling and maintenance. This paper describes a Bridge Transported Bilateral Force-Reflecting Servo-Manipulator (BTSM) system, which is being developed to overcome the limitation of access that is a drawback of the mechanical Master-Slave Manipulators (MSMs), which are mounted on the ACP hot cell wall for the operation and the maintenance of the ACP equipment. The BTSM system was manufactured and temporally installed at the mockup to test its performance. The manufactured BTSM system will be installed at the ACP hot cell on June 2005 after the accomplishment of the performance test. The BTSM system consists of four components: a transporter with a telescoping tubeset, a slave manipulator, a master manipulator, and a remote control system. This system will highly increase the volume of coverage for the operation and maintenance of the ACP equipment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.141-144
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• 2006

In this study, we developed a decladding device which separates 250 mm length of simulated nuclear spent fuel rod into the pallets and the pieces of the hulls after inserting the rod cut into the module with several pairs of blades. To improve the performance of the equipment, we considered some mechanisms to prevent the rod cut from being exposed or bounced into the hot-cell, to reduce the operation time, and to insert the rods automatically. It is expected that the newly developed system will contribute to prevent radioactive pollution in the hot-cell, reduce the operation time, and to increase the safety of the operators. As a result of the performance test for some mockup fuel rod cuts in the ACP(Advanced Spent Fuel Control Process) facility, it was verified that the decladding device could be applied to the actual fuel rod cut. And it will be able to use for a scale-up facility in the future.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1116-1120
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• 2004

In the nuclear power plant, there are several cylindrical vessels such as reactor vessel, pressuriser and so on. The vessels are usually constructed by welding large rolled plates, forged sections or nozzle pipes together. In order to assure the integrity of the vessel, these welds should be periodically inspected using sensors such as ultrasonic transducer or visual cameras. This inspection is usually conducted under water to minimize exposure to the radioactively contaminated vessel walls. The inspections have been performed by using a conventional inspection machine with a big structural sturdy column, however, it is so huge and heavy that maintenance and handling of the machine are extremely difficult. It requires much effort to transport the system to the site and also requires continuous use of the utility's polar crane to move the manipulator into the building and then onto the vessel. Setup beside the vessel requires a large volume of work preparation area and several shifts to complete. In order to resolve these problems, we have developed an underwater mobile robot guided by the laser pointer, and performed a series of experiments both in the mockup and in the real reactor vessel. This paper introduces our robotic inspection system and the laser guidance of the mobile robot as well as the results of the functional test.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.545-551
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• 2009

In naval architecture and offshore engineering, the development and a broad use has been achieved in the field of flow control valves for pipe system. Butterfly valves are also widely used for flow control, but there are not many studies for triple-eccentric butterfly valves. Moreover, if the fluid of pipeline flows in the bi-direction then it makes more complicate to adapt triple-eccentric butterfly valves to flow control. In this study, we are trying to develop a bi-directional triple-eccentric butterfly valve through sealing mechanism and stem design study. Digital mockup using 3D CAD was constructed for shape interference check and structural analysis was conducted for structural safety. Also we performed leakage test to check out the durability of the bi-directional pressure for the developed valve.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.1020-1023
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• 2009

It had been longer that the design mock-up was made mainly in order to test products. These days, it seems to be main stream that the working mockup is done because designers consider not only the design but also usability. In this study, the modular hardware toolkit, complimentary with Adobe Flash, was developed so that it solves the problem, the electronic hardware which the designers should struggle to make by themselves. This result thing could help the time of the design process to be short and contribute to make robust system rapidly.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.15-19
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• 2014

A Failure or degradation of reactor upper head penetration is a recurring problem due to long term operation at nuclear power plants. And a flaw in the reactor upper head penetration has caused unplanned plant shutdown for repair as well as high economic impact on the plants. Consequently, a detection of flaws is of the utmost importance. Prior to the replacement of reactor upper head penetration, some utilities have repaired the flaws of reactor upper head penetration generated by overlay weld. Until now, only the base metal in reactor upper head penetration has been inspected according to 10 CFR 50.55a and ASME code case N-729-1. Accordingly, it is difficult to detect manufacturing defects and repair defects in overlay weld. This paper presents a case study on the application of Time of Flight Diffraction technique for reactor head penetration mockup with artificial flaws in overlay weld. This study offers a way to understand the flaws detected in reactor upper head penetration overlay weld.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.68.4-69
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• 2018

GMACS is one of the instruments for the Giant Magellan Telescope (GMT) which will provide wide field, multi-object, moderate resolution spectroscopy of faint targets. KHU (Kyung Hee University) is in charge of control software of GMACS. As a first step, the Slit Mask Exchange Mechanism Prototype (SMEM-P) will be used as a preliminary example to make development process between electronics and high level software. Recently, we have developed a sample program to communicate with low level devices via EtherCAT. It is expected to be a mockup design for software and control system of GMACS. In this poster, we show the development process and test operation results of control software for SMEM-P.