• Journal of Radiation Protection and Research
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• v.49 no.1
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• pp.29-39
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• 2024

Background: The gamma emission tomography (GET) device has been reported a reliable technique to inspect partial defects within spent nuclear fuel (SNF) of pin-by-pin level. However, the existing GET devices have low accuracy owing to the high attenuation and scatter probability for SNF inspection condition. The purpose of this study is to design and optimize a Yonsei single-photon emission computed tomography version 2 (YSECT.v.2) for fast inspection of SNF in water storage by acquisition of high-quality tomographic images. Materials and Methods: Using Geant4 (Geant4 Collaboration) and DETECT-2000 (Glenn F. Knoll et al.) Monte Carlo simulation, the geometrical structure of the proposed device was determined and its performance was evaluated for the ¹³⁷Cs source in water. In a Geant4-based assessment, proposed device was compared with the International Atomic Energy Agency (IAEA)-authenticated device for the quality of tomographic images obtained for 12 fuel sources in a 14 × 14 Westinghouse-type fuel assembly. Results and Discussion: According to the results, the length, slit width, and septal width of the collimator were determined to be 65, 2.1, and 1.5 mm, respectively, and the material and length of the trapezoidal-shaped scintillator were determined to be gadolinium aluminum gallium garnet and 45 mm, respectively. Based on the results of performance comparison between the YSECT.v.2 and IAEA's device, the proposed device showed 200 times higher performance in gamma-detection sensitivity and similar source discrimination probability. Conclusion: In this study, we optimally designed the GET device for improving the SNF inspection accuracy and evaluated its performance. Our results show that the YSECT.v.2 device could be employed for SNF inspection.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.148-152
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• 2007

In recent days, on account of the cultural development and the improvement of citizen's consciousness level, it is the real situation that the construction of small-scaled Multi-Purpose Hall where various cultural events could be performed, is on increasing. However, since the most of Multi-Purpose Hall had been designed and built up without any consideration on Acoustic Factor, many problems are on occurring thereat. Since those small-scaled Multi-Purpose Hall have been mostly used with the finishing material which contains a high degree of Acoustic Absorption indiscreetly, both diffusion and reflection of sound are not establishing properly, and because thereverberation of sound is very low, in case of musical performance by musical instrument, its sound hears too arid and stiff, there occurs some acoustic defect such as it becomes difficult for music appreciation with sufficient timbre, so that the capability improvement on the matter is urgently requiring situation. Therefore, this Study has tried to seize the satisfaction level about the small-scaled Multi-Purpose Hall after betterment of the acoustic performance by appraise the acoustic condition of the Hall, using Auralization Technique that can experience Virtual Acoustic Field regarding to the small-scaled Multi-Purpose Hall as its object. It is deemed that such research result could be practically used as the useful material which enables to bring a reduction effect of construction cost as well asenhancement of the acoustic performance through its presupposition?control on the acoustic problem when construction or renovation of other similar small-scaled Multi-Purpose Hall in the future.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.206-211
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• 2010

Piezoelectric energy harvesting uses piezoelectric, which is able to convert unused mechanical vibration energy to electrical energy, such as with motor and machinery. The piezoelectric energy harvester was constructed with a cantilever made of lead zirconate titanate with a metal plate. The primary material was soft lead zirconium titanate (PZT-5H) due to the large strain availability, acceptable mechanical strength and high piezoelectric constant. This technique's drawback is that the energy efficiency is lower than the other energy harvesting methods, but this study increases the output electric power efficiency by analyzing a finite element method for the structure of the piezoelectric energy harvester. We manufactured two cantilever types as follows: the L-60 and L-33 bimorph piezoelectric energy harvesters. Their resulting energy harvesters were able to obtain high voltage values as follows: 27.4 mV and 40.6 mV. Moreover, these results have a similar band of resonance frequency it comparison to the simulation. Consequently, this study was confirmed with validity. The output electric powers of the L-60 and L-33 types have 3.1 mW/s and 5.8 mW/s with 47 Hz and 148 Hz of resonance frequency and then, the load resistivities were $100k\Omega$ and $10k\Omega$, respectively.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.197-207
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• 2000

A transient heat transfer analysis and thermo-elastic analysis have been performed for the residual stress distribution on the fillet weldment used by finite element method. Specimen is fabricated single-pass fillet welding. This computation was performed for conditions including surface heat flux and temperature dependent thermo-physical properties using by heat input as parameter. Also, cut-off temperature of residual stress estimation by thermo-elastic analysis is determined. The fillet weldment were measured to determined their residual stress distributions for using hole-drilling method. As result, it was found that large tensile residual stress is about material yield strength, and the numerical simulation results for finite element method similar to residual stresses by hole-drilling method and other exiting research. Also, cut-off temperature is effectively determined by temperature which calculated maximum thermal stress equal to material yield strength.

• Transactions of Materials Processing
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• v.16 no.8
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• pp.603-613
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• 2007

This paper is concerned with joining of thin metal sheets by single stroke clinching process. This method has been used in sheet metal work as it is a simple process and offers the possibility of joining similar-dissimilar thin sheet metals. Clinching generates a joint by overlapping metal sheets deforming plastically by punching and squeezing sequence. AA 5754 aluminum alloy of 0.5 mm thick sheets have been selected as a modal material and the process has been simulated under different process conditions and the results have been analyzed in terms of the quality of clinch joints which are influenced mainly by tool geometries. The rigid-plastic finite element method is applied to analyses in this paper. Analysis is focused mainly on investigation of deformation and material flow patterns influenced by major geometrical parameters such as die diameter, die depth, groove width, and groove corner radius, respectively. To evaluate the quality of clinch joints, four controlling or evaluation parameters have been chosen and they are bottom, neck thickness of bottom and top sheets, and undercut thickness, respectively. It has been concluded from the simulation results that the die geometries such as die depth and diameters are the most decisive process parameters influencing on the quality of clinch joints, and the bottom thickness is the most important evaluation parameter to determine if the quality of clinch joints satisfies the demand for industrial application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.188-193
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• 2011

The osseointegration of dental implant is influenced by many factors such as surface geometry, loading and the amount of bone. Thus, stability of the dental implant should be checked periodically. In order to test the stability of dental implant by using resonance frequency analysis, we designed a structure of transducers and fabricated a piezoelectric devices. Using finite element analysis, the thickness and length of piezoelectric device and transducers were tailorized and the optimized frequency of 10 kHz was obtained. The resonance frequency from simulation analysis and evaluation was estimated to be similar as 10 kHz. The osseointegration was further enhanced with increasing frequency from the evaluation result of the finite element analysis.

• Composites Research
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• v.32 no.2
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• pp.113-119
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• 2019

The objective of this research is to study the mechanical and vibration characteristics of vibration damping aluminum panels for automotive parts. For this purpose, the test and simulation results of aluminum-resin hybrid materials and aluminum sheet materials were compared. Tensile strength and elastic modulus of the hybrid material were approximately 10% lower than aluminum sheet. Also, it was showed that the hybrid material have lower natural frequency than aluminum sheet, and it was confirmed that loss factor increases as the thickness of resin increases. Finally, it is confirmed that the test results and the analysis results are similar with each other and the performance prediction of the materials are possible by FEA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.158-163
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• 2023

Recently, the global demands for high voltage power semiconductors are increasing across various industrial fields. The use of electric cars with high safety and convenience is becoming practical, and IGBT modules of 3.3 kV and 1.2 kA or higher are used for electric locomotives. Delicate design and advanced process technology are required, and research on the optimization of high-voltage IGBT parts is urgently needed in the industry. In this study, we attempted to design a simulation process through TCAD (technology computer-aid design) software to optimize the process conditions of the fielding process among the core unit processes for an especial high yield voltage. As well, the prior circuit technology design and a ring pattern with a large number of ring formation structures outside the wafer similar to the chip structure of other companies were constructed for 3.3 kV NPT-IGBT through a unit process demonstration experiment. The ring pattern was designed with 21 rings and the width of the ring was 6.6 ㎛. By changing the spacing between patterns from 17.4 ㎛ to 35.4 ㎛, it was possible to optimize the spacing from 19.2 ㎛ to 18.4 ㎛.

• Child Health Nursing Research
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• v.19 no.1
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• pp.1-11
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• 2013

Purpose: This study was done to develop a scenario and evaluate student performance in simulation learning of care for children with respiratory distress syndrome in neonatal intensive care units. Methods: To test the application effect, a one group pre-test design was applied. The scenario based on actual patients and textbook material was developed through several meetings of experts. The scenario was used with 17 groups of 55 senior nursing students who participated voluntarily. Results: Contents were organized focusing on the nursing process for simulation learning. In the application of knowledge and skills, nursing students had high scores in the contents of observation of oxygen saturation, and care to relieve dyspnea. Participants' ability, especially in suction and oxygen supply in the evaluation of objective structured clinical examination was not adequate. There was a significant positive correlation between problem-solving ability and satisfaction in learning. Conclusion: The respiratory distress syndrome simulation scenario developed in this study was an effective tool to give students experience in problem solving and critical thinking ability under conditions similar to reality. The development of various scenarios for child nursing care is needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7534-7540
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• 2015

In this paper, we set up a vista point overlooking the focus of new research center placed on the existing research literature and point to the selection of books, reports or studies actually suggested focusing on topics such as for landscape simulation evaluation. To re-organize and classify a number of items were presented to spill the evaluation items of this view point selection via the SPSS Statistics. Evaluation items 16 through a professional survey to establish a concrete and systematic plan with selected research results leaked technical characteristics of the view that detailed questions to the factors of technical characteristics and population-specific comparisons through factor analysis in the first, landscapes simulation The views were set out. Second, if you set 16 classified by type of view that considering a similar nature or characteristics depending on the properties of the view that publicity, overlooking castle, the castle was divided into three types of places. Third, the views point for the public good are three items, vista point at which the gender perspective has six items that gender point of view places is set to seven items, was set up to view the most appropriate place to point gender. These results provide a framework for analysis and future system reliability and landscape simulation evaluation study is expected to be used as reference material.