• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.11-20
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• 2021

Decontamination of systems, structures and components (SSC) during the decommissioning of a Nuclear Power Plant (NPP) can be for a variety of reasons. The main reasons for decontamination are: to reduce the contamination of SSC to a reasonably low level, to reduce the potential for the spread of contaminants into the environment and to reduce the cost of disposal due to the reduced level of contamination in a particular SSC. The decontamination technique can be aggressive or non-aggressive depending on the intent after the decontamination process. Aggressive decontamination technique is used when the intent is not to reuse the SSC while a non-aggressive decontamination technique is used with the intent of SSC reuse. For different SSCs there are different decontamination techniques that can be used, each having its own advantages and drawbacks. Metal components such as pipes in the nuclear power plant account for a large amount of nuclear wastes generated. Some of these wastes can be reused if the contaminant level is reduced to an acceptable level. Laser ablation is a non-aggressive decontamination technique that can be used to reduce the contamination in pipes to an acceptable level with no secondary waste generated during the process. The operation and control of a laser ablation device must be precise to achieve a high decontamination factor. This precision can be achieved by a well-designed motion control system. For this purpose, a motion control system was developed consisting of two parts: the first part being the precise control of the laser ablation device inside the pipe and the second part is the control of the laser ablation device outside the pipe. This paper describes the Systems Engineering approach for the development process of a motion control system for the Laser decontamination system.

• Journal of Astronomy and Space Sciences
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• v.30 no.1
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• pp.49-58
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• 2013

ARGO-M is a satellite laser ranging (SLR) system developed by the Korea Astronomy and Space Science Institute with the consideration of mobility and daytime and nighttime satellite observation. The ARGO-M optical system consists of 40 cm receiving telescope, 10 cm transmitting telescope, and detecting optics. For the development of ARGO-M optical system, the structural analysis was performed with regard to the optics and optomechanics design and the optical components. To ensure the optical performance, the quality was tested at the level of parts using the laser interferometer and ultra-high-precision measuring instruments. The assembly and alignment of ARGO-M optical system were conducted at an auto-collimation facility. As the transmission and reception are separated in the ARGO-M optical system, the pointing alignment between the transmitting telescope and receiving telescope is critical for precise target pointing. Thus, the alignment using the ground target and the radiant point observation of transmitting laser beam was carried out, and the lines of sight for the two telescopes were aligned within the required pointing precision. This paper describes the design, structural analysis, manufacture and assembly of parts, and entire process related with the alignment for the ARGO-M optical system.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.41-47
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• 2010

There are many unbalanced models such as helicopter's rotor blades, small-sized precision motor in industrial applications. In the real products, their gravity center usually does not accord with the desired gravity center. If the deviation is large between them, it can be a major cause of vibration and noise as the part of model rotate. Therefore the gravity center in the rotational parts should be controlled properly because of static and dynamic balancing of the parts. In the research, the rotor blade of unmanned helicopter has been selected to obtain the high quality of balancing. In order to achieve the purpose, measuring system has been developed. In the system applied principle is three point weighting method, which is one of the Multiple-point Weighting Method. It has circle fitting for compensation of machining error, after measuring the values. From this study, the results showed that the proposed measurement procedure gives reliable and precise gravity center.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2757-2763
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• 2015

p-Snake is an energy minimizing algorithm that applies an additional prototype energy to the existing Active Contour Model and is used to extract the contour line in the area where the edge information is unclear. In this paper suggested the creation of a prototype energy field that applies a variable prototype expressed as a combination of circle and straight line primitives, and a fudge function, to improve p-Snake's contour extraction performance. The prototype was defined based on the parts codes entered and the appropriate initial contour was extracted in each primitive zones acquired from the pre-processing process. Then, the primitives variably adjusted to create the prototype and the contour probability based on the distance to the prototype was calculated through the fuzzy function to create the prototype energy field. This was applied to p-Snake to extract the contour from 100 images acquired from various small parts and compared its similarity with the prototype to find that p-Snake made with the adaptive prototype was about 4.6% more precise than the existing Snake method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.91-97
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• 2017

The purpose of this study is to get a more precise frequency of hollow core slabs by comparing the observed values from the actual free vibration tests and the predicted values based on the analysis model. The actual free vibration tests were carried out in the construction field using ${\Omega}$ shaped hollow core slabs. Modal analysis is conducted based on the analysis model that takes into account the differences in section properties due to void parts of slab. The differences between the predicted values based on the modal analysis with analysis model and the measured data from the actual tests range from 2~7%. This study demonstrates that the analysis model that incorporates void parts of slab could be used in evaluating serviceability of hollow core slabs with reasonable accuracies.

• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.23-27
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• 2011

Due to a roots type medium vacuum pump is operated in condition of $1{\sim}10^{-3}$ torr vacuum, it could be applied for production and process of industrial parts, such as precise processing, vaporization, enrichment, separation, casting, metaling, welding, transportation. Therefore, the demand of this pump is increasing nowadays in our industrial markets of semiconductor, electric, electronic, automobile, material, environmental and transporting industries. However, the pumps are almost imported, because the domestic pumps are inferior in fields of vacuum range as under $10^{-1}$torr, relevant techniques(design, fabrication, casting, test, etc.) to the imported ones. In this study, essential parts of the development pump are designed with using of CFD and 3D decodes, FEM for analysing strength and deformation, generated heat, vibration and noise control, and are casted with using of mechanochemistry techniques for decreasing of weights, increasing of heat resistances and abrasion durability of materials for pump caing and impellers especially. Besides, in order to achieve ultimate vacuum around $10^{-3}$torr, this pump is composed of 6 stages, among which 1st stage is operated separately from remained stages. Additionally, a test rig for prototype pumps(300$m^3/h$ and 2,500$m^3/h$) is designed and procured as to apply for multi-staged rootz type vacuum pump, with modification of the test method recommended by KS B 6314 "Positive-displacement oil-sealed rotary vacuum pumps".

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.1-6
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• 2019

With the increase in number of the athletic population and elderly demographic, the demand for orthopedic splints, which are used to support a damaged body, has rapidly increased. Current splints mainly consist of inner and outer parts, which are multiple fabrics covered with polyurethane and nonwoven fabrics, respectively. However, the laminated materials with directly applied pre-polymer coating lead to a high defect rate because of the uneven thickness on the surface. Thus, this study proposes an indirect coating method using a precise clearance controller, which enables the even application of the coating material on multiple inner parts while maintaining a constant thickness. In addition, a roll-to-roll (R2R) technique is applied instead of the sewing mechanism to bond the inner and outer materials together and enhance the productivity in the final stage. In the advanced methods, there is a storage tank that contains polyurethane, a clearance controller, and pairs of rollers in the upper and lower rows. To improve the quality of the products and optimize the equipment, three controllable factors are determined: the viscosity of polyurethane, angle of the gap controller and number of pairs of rollers in the R2R system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.41-47
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• 2020

As modern industries are highly being developed, it is required that mechanical parts have to be manufactured with a high precision. In order to have precise parts, error-free designs have to be done before manufacturing with accuracy. For this intention being fulfilled, a mechanical analysis is essential for design proof. Nowadays, FEM simulation is a popular tool for verifying a machine design. In this paper, an impeller, being utilized in a compressor or an oil mixer as an actuator, is studied for an evaluation. The purpose of this study is to present a safety of an impeller for a proof of its mechanical stability. A static analysis for stress, strain, and deformation within a regular usage is examined. This simulation test shows 357.26×106 Pa for maximum equivalent stress and 0.207mm for total deformation. A fatigue test is carried to provide durability and its result shows that minimum safety factor is 3.2889, which guarantees that it runs without a fatigue failure in 106 cycles. The natural frequencies for the impeller is ranged from 228.09Hz to 1,253.6Hz for the 1st to the 6th mode. Total deformations at these natural frequencies are shown from 6.84mm to 12.631mm. Furthermore, Campbell diagram reveals that a critical speed is not found throughout regular rotational speeds. From the test results for the analysis, this paper concludes that the suggested impeller is proved for its mechanical safety and good to utilize at industries.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.593-599
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• 2023

There is risk of derailment due to various factors such as vehicle-track load imbalance in curved parts, so urban railways install and operate derailing prevent guard rails. The angle-type derailing prevent guard rail is composed of various parts including the guard angle. Even if derailment does not occur, various damages occur in the components, so continuous maintenance is required. Through the damage status analysis, the components of the angle-type derailing prevent guard rail with high damage frequency were classified, and conditions for the occurrence of various damages were investigated. In addition, a numerical analysis using a precise 3D numerical model was performed to analyze the cause of the damage analytically. In order to analytically simulate the derailment situation, the static ultimate load condition was applied, and the actual drawing of the angle-type derailing prevent guard rails, rails, and wheels was used for modeling. By analyzing the results of the damage status investigation and finite element analysis, we tried to investigate the damage of the components.

• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.469-478
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• 1997

This study was conducted to develop an automatic nutrient-solution mixing system for small-scale sewers. The nutrient-solution mixing system consisted of a low-cost and precise metering device and data acquisition ＆ control system with a personal computer. and, the metering device was composed of three parts those were supply pumps, metering cylinders and venturi tube. The system controlled electric conductivity(EC) and pH of nutrient-solution based on the time-based feedback control method with the information about temperature, EC, and pH of the nutrient-solution. The performance of the nutrient-solution mixing system was evaluated through the control of EC and pH while compared with those of commercial system. Also an experimental cultivation of tomato was conducted to verify and to improve the developed system. Results of this study were as follows. 1. The correlation coefficient of meteing device between the flow rate and operating time was 0.9999, and the linear reuession equation computed was y=21.759x, where y is the discharge($g$) and x is the operating time(s). 2. Calculated errors for the developed metering device and two commercial pump were $\pm$0.3% $\pm$2.45% and $\pm$1.38 % FS error respectively. 3. An automatic nutrient-solution mixing system based on a low-cost and precise metering device was developed. 4. The full scale errors of the developed system in controlling EC and pH at 23$\pm$1$^{\circ}C$ were $\pm$0.05mS/cm and $\pm$0.2, respectively 5. When using the commercial system, the controlled values of EC and pH of the 500 $\ell$ of water were 1.29 mS/cm and 6.1 pH for the setting points of 1.4 mS/cm and 6.0 pH respectively at 23$pm1^{\circ}C$. 6. The developed nutrient-solution control system showed $\pm$0.05 ms/cm of deviation from the setting EC value over the experimental cultivation period. 7. The deviation from the average values of Ca and Mg mass content in the several nutrient-solution were 0.5% and 1.8% respectively.