• Journal of Advanced Navigation Technology
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• v.28 no.3
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• pp.356-361
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• 2024

This paper deals with the design and fabrication of a coplanar waveguide (CPW)-fed super-wideband semicircular-disk-shaped dipole antenna operating in a frequency band of 2.4 GHz or higher. To feed the antenna, a CPW feed line was appended to the center of the lower arm of the semicircular-disk-shaped dipole antenna. For miniaturization, square patches were added to the ends of the two arms of the semicircular-disk-shaped dipole, whereas the slot width of the CPW feed line at the center of the dipole antenna was increased to improve impedance matching in the 5.4-6.3 GHz band. The simulated frequency band of the proposed antenna for a voltage standing wave ratio (VSWR) less than 2 was 2.369-30 GHz(170.7%), whereas the fabricated antenna was maintained VSWR less than 2 in the frequency range of 2.378-20 GHz when measured using a network analyzer operating up to 20 GHz so it can be applied as a super-wideband antenna for next-generation mobile communications.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.93-98
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• 2024

With the rapid advance in AI (artificial intelligence) and high-performance computing technologies, deep learning is being used in various fields. Deep learning proceeds training by randomly reading a large amount of data and repeats this process. A large number of files are randomly repeatedly referenced during deep learning, which shows different access characteristics from traditional workloads with temporal locality. In order to cope with the difficulty in caching caused by deep learning, we propose a new sampling method that aims at reducing the randomness of dataset reading and adaptively operating on existing buffer cache algorithms. We show that the proposed policy reduces the miss rate of the buffer cache by 16% on average and up to 33% compared to the existing method, and improves the execution time by up to 24%.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.232-237
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• 2024

In this paper, a broadband double dipole quasi-Yagi antenna using a 4×2 meander line array structure for maintaining 8 dBi gain was studied. The 4×2 meanderline array structure consists of a unit cell in the shape of a meanderline conductor, and it was placed above the second dipole antenna of the double dipole quasi-Yagi antenna. A double dipole quasi-Yagi antenna with generally used multiple strip directors was designed on an FR4 substrate with the same size, and the input reflection coefficient and gain characteristics were compared. Comparison results showed that the impedance frequency bandwidth increased by 6.3% compared to when using the multiple strip directors, the frequency bandwidth with a gain of 8 dBi or more increased by 10.1%, and average gain also slightly increased. The frequency band of the fabricated antenna for a voltage standing wave ratio less than 2 was 1.548-2.846 GHz(59.1%), and gain was measured to be more than 8 dBi in the 1.6-2.8 GHz band.

• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.261-269
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• 2024

In this paper, the acoustic performance of an absorptive silencer was enhanced by optimizing an arrangement of multi-layered absorbing materials. The acoustic performance of the silencer was evaluated through transmission loss, and finite element method-based numerical analysis program was employed to calculate the transmission loss. Polyurethane, a porous elastic material frequently used in absorptive silencers, was employed as the absorbing material. The Biot-Allard model was applied, assuming that air is filled inside the polyurethane. By setting the frequency range of interest up to the 2 kHz and the acoustic performance affecting properties of the absorbing materials were investigated when it was composed as a single layer. And the acoustic performance of the silencers with the single and multi-layered absorbing materials was compared with each other based on polyurethane material properties. Subsequently, the arrangement of the absorbing materials was optimized by applying the Nelder-Mead method. The results demonstrated that the average transmission loss improved compared to the single-layered absorptive silencer.

• Journal of The Korean Institute of Defense Technology
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• v.5 no.1
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• pp.7-18
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• 2023

The military leader makes an operation plan to accomplish combat missions. The current doctrine for an operation planning requires the use of simple and clear procedures and methods that can be carried out with human effort under adverse conditions in the field. The work in the process of an operation planning can be said to be a series of decision-making, and the criteria for decision-making generally apply mission variables. However, detailed standards are not fixed as doctrine, but are creatively established and applied. However, for AI-based decision-making, it is necessary to formalize the criteria and the format used. This paper first aims to standardize various criteria and forms to present a method that can be used in a semi-automated assist system, and to seek a plan to artificialize it. To this end, mathematical models and decision-making methods established in the field of operations research were applied to improve efficiency.

• Journal of Internet Computing and Services
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• v.25 no.3
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• pp.19-25
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• 2024

The worldwide aging population trend is causing an increase in the incidence of major retinal diseases that can lead to blindness, including glaucoma, cataract, and macular degeneration. In the field of ophthalmology, there is a focused interest in diagnosing diseases that are difficult to prevent in order to reduce the rate of blindness. This study proposes a deep learning approach to accurately diagnose ocular diseases in fundus photographs using less data than traditional methods. For this, Convolutional Neural Network (CNN) models capable of effective learning with limited data were selected to classify Conventional Fundus Images (CFI) from various ocular disease patients. The chosen CNN models demonstrated exceptional performance, achieving high Accuracy, Precision, Recall, and F1-score values. This approach reduces manual analysis by ophthalmologists, shortens consultation times, and provides consistent diagnostic results, making it an efficient and accurate diagnostic tool in the medical field.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.538-543
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• 2024

In this paper, the miniaturization of a chipless RFID tag using an interdigital-capacitor-shaped slot was studied. The proposed interdigital-capacitor-shaped slot was appended on the rectangular conductor plate printed on one side of a 20 mm × 50 mm FR4 substrate with a thickness of 0.8 mm. The resonant dip frequency of the bistatic RCS for the proposed interdigital-capacitor-shaped slot was compared with the cases when the H-shaped and modified bent H-shaped slots were added, respectively, on the conductor plate. The simulated resonant dip frequencies for H-shaped and modified bent H-shaped slots were 5.907 GHz and 3.741 GHz, respectively. When the proposed interdigital-capacitor-shaped slot was added, the resonant dip frequency was decreased to 2.889 GHz, and, therefore, the slot length was reduced by 51.1% compared to the H-shaped slot case. Experiment results show that the resonant dip frequency of the fabricated nterdigital-capacitor-shaped slot was 3.07 GHz.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.574-581
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• 2024

This study explores the usability of extended reality (XR) content tailored for production process training, with a focus on user experience. Participants engaged with extended reality training modules, and qualitative data was subsequently collected through interviews. These interviews evaluated the hardware, user interface, and overall user satisfaction. The analysis utilized python packages for keyword extraction and word cloud visualization, offering insights into user perceptions. The findings revealed that although the hardware was deemed comfortable, concerns were raised regarding its weight and heat emission. The interactive interface, which relies on hand tracking, encountered issues with recognition rates, leading to suggestions for alternative input methods. Users acknowledged extended reality's potential impact on industries like healthcare and education, sharing both positive and negative views on the technology. This research enhances our understanding of user responses and guides the future enhancement of extended reality content for industrial applications, aiming to improve its quality and practical usability

• Korean Journal of Clinical Laboratory Science
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• v.56 no.3
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• pp.277-287
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• 2024

Transcranial Doppler (TCD) ultrasound is a crucial non-invasive tool for assessing cerebral blood flow and is widely used to diagnose and monitor cerebrovascular diseases. This paper reaffirms the importance of TCD, details examination methods and precautions, and provides a guide for practitioners. TCD evaluates the blood flow velocity to assess stenosis, occlusion, and hemodynamic changes. Distinguishing between increased blood flow volume and decreased vessel diameter based solely on velocity is challenging, necessitating a comprehensive approach to integrating clinical findings and hemodynamic changes. The reliability of TCD results depends on the skill of the examiner and requires standardized procedures and continuous training. Advances in automation and artificial intelligence promise enhanced accuracy and reliability. Future research should focus on validating and clinically applying these technologies. This paper is a review of the clinical significance of TCD, methods, and precautions, offering a valuable guide for practitioners and highlighting the potential benefits of ongoing advancements in TCD for the diagnosis and treatment of cerebrovascular diseases.

• Steel and Composite Structures
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• v.52 no.6
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• pp.647-656
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• 2024

This paper discusses the study of concrete composite walls of algorithmic modeling, in which steel tubes are embedded. The load-bearing capacity of STHC composite walls increases with the increase of axial load coefficient, but its ductility decreases. The load-bearing capacity can be improved by increasing the strength of the steel pipes; however, the elasticity of STHC composite walls was found to be slightly reduced. As the shear stress coefficient increases, the load-bearing capacity of STHC composite walls decreases significantly, while the deformation resistance increases. By analyzing actual cases, we demonstrate the effectiveness of the research results in real situations and enhance the persuasiveness of the conclusions. The research results can provide a basis for future research, inspire more explorations on seismic design and construction, and further advance the development of this field. Emphasize the importance of research results, promote interdisciplinary cooperation in the fields of structural engineering, earthquake engineering, and materials science, and improve overall seismic resistance. The emphasis on these aspects will help highlight the practical impact of the research results, further strengthen the conclusions, and promote progress in the design and construction of earthquake-resistant structures. The goals of this work are access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient architecture, sustainable planning and management of human settlements. Simulation results of linear and nonlinear structures show that this method can detect structural parameters and their changes due to damage and unknown disturbances. Therefore, it is believed that with the further development of fuzzy neural network artificial intelligence theory, this goal will be achieved in the near future.