• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.147-159
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• 2024

Plutonium-238 has always been considered as the one of the promising radioisotopes for space nuclear power supply, which has long half-life, low radiation protection level, high power density, and stable fuel form at high temperatures. The industrial-scale production of ²³⁸Pu mainly depends on irradiating solid ²³⁷NpO₂ target in high flux reactors, however the production process faces problems such as large fission loss and high requirements for product quality control. In this paper, a conceptual design study of producing ²³⁸Pu in a multi-purpose high flux reactor was evaluated and analyzed, which includes a sensitivity analysis on ²³⁸Pu production and a further study on the irradiation scheme. It demonstrated that the target structure and its location in the reactor, as well as the operation scheme has an impact on ²³⁸Pu amount and product quality. Furthermore, the production efficiency could be improved by optimizing target material concentration, target locations in the core and reflector. This work provides technical support for irradiation production of ²³⁸Pu in high flux reactors.

• Journal of Biomedical Engineering Research
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• v.45 no.3
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• pp.109-117
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• 2024

We developed a device that integrates digital otoscope and stethoscope for telemedicine. The integrated device was utilized for the collection of tympanic membrane images and cardiac auscultation data. Data accumulated on the platform server can support real-time diagnosis of heart and eardrum diseases using artificial intelligence. Public data from Kaggle were used for deep learning. After comparing with various deep learning models, the MobileNetV2 model showed superior performance in analyzing tympanic membrane data, and the VGG16 model excelled in analyzing cardiac data. The classification algorithm achieved an accuracy of 89.9% for eardrums data and 100% for heart sound data. These results demonstrate the possibility of diagnosing diseases without the limitations of time and space by using this platform.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4642-4646
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• 2023

The Tb³⁺ or Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor were fabricated by funace at 1500 ℃ for 12 h using a solid state reaction. The XRD (X-ray diffraction_Panalytical X'Pert Pro) and FE-SEM (field emission scanning electron microscope) are measured to confirm the crystalline structure and surface morphology of the phosphor. The Tb³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor emits the lights in 470~650 nm wavelength range due to transitions from ⁵D₄ to ⁷F_j. Therefore, it shows the green region in the CIE chromaticity diagram under both UV and X-rays excitations. The Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor emits the lights in 550~750 nm wavelength range because of ⁵D_i to ⁷F_j. The emission is confirmed to be in the red region using the CIE chromaticity diagram. The Tb³⁺ or Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor shows the characteristic f-f transition with a long decay time, which is about several milliseconds. They have the high efficiency of light emission for X-ray because of their high effective Z number (Z_eff = 58.5) and density. Therefore, they are very much promising phosphors for X-ray imaging application in medical fields.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2011-2018
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• 2024

Since RF breakdown is one of the primary limitations to improving the performances of RF accelerators, extensive efforts have been dedicated to locating the breakdowns. However, most existing methods rely on specialized techniques, resulting in high financial burdens. Although the method based on transient response of transmission line (TL) is suitable for facilities with sporadic recoverable breakdowns, practical operations are susceptible to notable errors. This study revisits the fundamental theories of lossless TL and investigates the wave process to understand the characteristics of the reversed pulse induced by the breakdowns. By utilizing steadystate response of the TL and employing phasor method, we derive analytical formulas to determine the exact location of breakdowns within the faulty cell for constant-gradient TW accelerator. Furthermore, the derived formulas demonstrate their independence from RF phase, thereby distinguishing them from traditional phasebased methods. Additionally, experimental validations are conducted at the HUST injector, and the results confirm the consistency of the analysis. Thus, the proposed method represents a promising improvement over the TL-based approaches and serves as a valuable complement to current techniques. Importantly, this method demonstrates particular advantages for constructed TW accelerators seeking to achieve a balance among high performance, low costs, and compact layouts.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2718-2731
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• 2024

To ensure the operational safety of nuclear power plants, we present a Quadruped Inspection Robot that can be used for many types of steam generators. Since the Inspection Robot relies on the Holding Modules to grip the tube-sheet, it can be regarded as a hybrid robot with variable configurations, switching between 4-RRR-RR, 3-RRR-RR, and two types of 2-RRR-RR, and the variable configurations bring a great challenge to dimensional synthesis. In this paper, the kinematic model of the Inspection Robot in multiple configurations is established, and the analytical solution is given. The workspace mapping is analyzed by the solution-space, and the workspace of multiple configurations is decomposed into the workspace of 2-RRR to reduce the analysis complexity, and the workspace calculation is simplified by using the envelope rings. The optimization problem of the manipulator is transformed into the calculation of the shortest contraction length of the swing leg. The switching performance of the Inspection Robot is evaluated by stride-length, turning-angle, and workspace overlap-ratio. The performance indexes are classified and transformed based on the proportions and variation trends of dimensional parameters to reduce the number of optimization objective functions, and Pareto optimal solutions are obtained using an intelligent optimization algorithm.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.492-501
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• 2009

This study was carried out to investigate influence of tree height on vegetable growth, productivity, and labor input in 5 year old slender spindle 'Fuji'/M.9 apple trees planted with the tree space of $3.2{\times}1.2m$ and trained to the tree height of 2.5m in the apple orchard of Apple Research Station, NIHHS, RDA in Gunwi County, Korea. Tree height was extended to the tree height of 4.0m for two years. And then, the tree height was restricted to 2.5 (control), 3.0, 3.5, and 4.0m in 8th year. Yield per 10a was 46, 25, and 4% higher at the tree height of 4.0, 3.5, and 3.0m than at the tree height of 2.5m respectively in first year and 17, 12, and 10% higher respectively, indicating the taller tree, the higher yield. Soluble solid contents was highest in the height of 2.5m than in any other treatments for 2 years, but fruit skin color was not clear. Labor input was increased parallel with the increase of tree height, but yield per labor input was decreased. Gross income and net income per 10a were increased parallel with the increase of tree height in first year, but not increased in second year. In considering production, labor input, and economic efficiency, the optimum tree height of slender spindle 'Fuji'/M.9 apple planted with the tree space of $3.2{\times}1.2m$ was presumed to be 3.0~3.5m.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.331-346
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• 2018

In the tunnel of domestic high - speed railway, the main fire - fighting facility, fire - extinguishing passageway, is installed. However, due to the high pressure of the high - speed train, frequent breakage and maintenance are caused by strong shock and long - term vibration. In order to solve these problems, it is necessary to improve the fire door, but in Korea, it is installed by submitting a certificate by simple KS F 2296 performance test. At present, it is developed as a simple test certification by producing a real scale fireproof door without the theoretical examination in advance, so that a high cost for improvement is occurring in Korea. Therefore, through this study, structural analysis study which can preliminary structure review was carried out in order to design the refuge connection passage fire door and to improve the performance improvement. In order to secure the reliability of the result value, the official authentication test (KS F 2296) were compared.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.9
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• pp.916-920
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• 2008

The personal workspace consists of user- specified computing environment such as user profile, applications and their configurations, and user data. Mobile computing devices (i.e., cellular phones, PDAs, laptop computers, and Ultra Mobile PC) are getting smaller and lighter to provide personal work-space ubiquitously. However, various personal work-space mobility solutions (c.f. VMWare Pocket ACE[1], Mojopac[2], u-PC[3], etc.) are appeared with the advance of virtualization technology and portable storage technology. The personal workspace can be loaded at public PC using above solutions. Especially, we proposed a framework called ubiquitous personal computing environment (u-PC) that supports mobility of personal workspace based on wireless iSCSI network storage in our previous work. However, previous u-PC could support limited applications, because it uses IRP (I/O Request Packet) forwarding technique at filter driver level on Windows operating system. In this paper, we implement OS-level virtualization technology using system call hooking on Windows operating system. It supports personal workspace mobility and covers previous u-PC limitation. Also, it overcomes personal workspace loading overhead that is limitation of other solutions (i.e., VMWare Pocket ACE, Mojopac, etc). We implement a prototype consisting of Windows XP-based host PC and Linux-based mobile device connected via WiNET protocol of UWB. We leverage several use~case models of our framework for proving its usability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.1
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• pp.71-88
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• 2003

The DRASTIC system is widely used for assessing regional groundwater pollution susceptibility by using hydrogeological factors such as depth to water, net recharge, aquifer media, soil media, topography, vadose zone media, hydraulic conductivity. This study is providing Modified Drastic Model to which lineament density, land use, influence of groundwater drawdown caused by tunnel excavation are added as additional factors using geographic information system, and then to evaluate groundwater contamination potential of ${\bigcirc}{\bigcirc}$ area. For statistical analysis, vector coverage per each factor is converted to grid layer and after each correlation coefficient between factors, covariance, variance, eigenvalue and eigenvector by principal component analysis of 3 direction, are calculated, correlation between factors is analyzed. Also after correlation coefficients between general DRASTIC layer and rated lineament density layer, between general DRASTIC layer and rated land use layer, between general DRASTIC layer and rated tunnel excavation influence layer are calculated, final modified DRASTIC model is constructed by using them with each weighting. When modified DRASTIC model was compared with general DRASTIC model, contamination potential in modified DRASTIC model is fairly detailed and consequently, vulnerable area which has high contamination potential could be presented concretly.

• Journal of Distribution Research
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• v.16 no.5
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• pp.103-122
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• 2011

This study suggests regionally closely-related traditional market support measures that are intended. Market and the community to investigate the relationship between traditional markets and the degree of relationship with the local economy, whether the degree of cooperation with local communities, local people in stores and traditional markets, with a visual image, interacting with local relevance were. Executed questionnaire to merchants and traditional market connection specialists of the tradition market engaged to whole country small town. Small town region's traditional markets have a close relationship with the community. Contribute to regional economic development, and locals have a passion for shopping. Small town to enable local traditional market requires the following way. Through surveys and research policy implications are as follows: First, by constructing a civil partnership with a focus on the needs of local residents need market activation measures. Second, the traditional market members to build social relationships that contribute to their local needs. Third, Installation and utilization of community space in traditional markets is required. Fourth, to increase the participation of young people need to be developed in the program. Fifth, small town regional market collapse and space reorganization is needed.