We have studied the passive millimeter-wave imaging system with multichannel receiver. The system is consist of lens, one dimensional receiver array, receiver scanner and DSP processor. We obtained the key parameters such as temperature sensitivity, spatial resolution and frame rate using mathematical modeling. We propose a structure with a small, low-noise W-band multi-channel receiver on the imaging surface by condensing millimeter waves using an optical system lens. Dielectric rod antenna was used because of high gain and low side lobe. The radiation pattern of the designed rod antenna obtained simulation results of about 52° for E-plane and 51.4° for H-plane and it was found that E and H side had the same pattern. The receiver for low loss and low noise has been designed assembling all components such as waveguide and microstrip transition, LNA, band pass filter, detector on a single substrate. In the case of waveguide-microstrip transition, the receiving unit was found to have characteristics of less than about 0.3 dB of insertion loss and -24 dB of reflection loss at 94 GHz and 8 GHz of bandwidth. the designed amplifier obtained noise figures of 4.1 dB and gains of over 30 dB.

This study identified the level of meaning in life of hearing-impaired people who use hearing aids. Hearing impairment due to irreversible damage is very important in that the use of hearing aids improves communication and improves the quality of life for people with hearing loss. Accordingly, a survey was conducted on the level of meaning in life among hearing-impaired people who use hearing aids, and the final 168 people were analyzed. As a main research result, the subjects' overall level of meaning in life was found to be 5.80 points. In particular, wearing hearing aids was found to provide enjoyment and satisfaction in life. To ensure that many people with hearing loss can use hearing aids in the future, research on the need for hearing aid support and a realistic support system such as hearing aid purchase and follow-up management are needed.

In many polls, fighting officers are rated as the most admired profession by the public. However, the reality is that fighting officers make many mental sacrifices in the field of disaster response. Unfortunately, the academic research to make Korea a safe country for fighting officers suffering in fire, rescue, and aid scenes is slow. In this study, we conducted a comparative analysis of fighting officers' meaning in life by job function. The results showed that rescue workers had the highest meaning in life(M=5.45) and first aider had the lowest (M=4.81). It is hoped that future academic interest and consideration by the Fire Department will lead to research and policies to relieve disaster stress among first aiders.

This paper analyzes the characteristics of common mode voltage and leakage current in a motor drive system that includes the dual inverters based on various pulse width modulations. The use of power conversion devices increases due to technological advances and environmental regulations, systems that integrate multiple devices and loads are growing. High switching frequencies improve efficiency and control performance. However, they can lead to an increase in common mode voltage and high frequency leakage current. It can reduce system reliability and electromagnetic interference. Therefore, this study aims to analyze the common mode voltage and leakage current according to the pulse width modulations with the dual inverters.

Recently, a technique has been developed to harmlessly treat surface microcrack through surface modification. This technique has the advantage of increasing fatigue life by harmlessly treating surface microcrack that occur during machining and operation. In this study, to prevent a decrease in the fatigue limit of carbonitriding products, specimens were produced by performing a double shot peening (DSP) after tempering at 573K. Using the compressive residual stress due to DSP, the harmless crack size was calculated. The specimens tempered at 573K showed little change in surface properties even when the temperature increased during operation. The surface hardness of the specimens tempered at 573K after DSP was lower due to the phase transformation occurring during the DSP and 573K tempering process. The specimens subjected to DSP after 573K tempering exhibited higher maximum compressive residual stress and fatigue limit. The crack size that could be rendered harmless was derived from the residual stress of the carbonitriding steel.

This paper proposes a fault detection algorithm for switch open of dual 3-phase inverter using arctangent function based on phase information. In general, the dual 3-phase inverter is widely a power conversion device used to drive asymmetric 6-phase PMSMs, and is chosen in automation, aerospace, and military industries that utilize high output, high torque, and high reliability of multi-phase motors. In this paper, the fault types, phase currents, and synchronous coordinate DQ-axis current characteristics according to switching open faults of the dual 3-phase inverter are analyzed. As a result, the switch open fault diagnosis algorithm using the arctangent function based on phase information is proposed. The phase information can be generated by using virtual current components with 90 degree phase difference and individual phase currents to detect switch open faults of each phase. The proposed algorithm can quickly check whether individual switches are open through simple software configuration for each phase. The effectiveness of the proposed technique has been proven through numerous experiments.

The special alloy, for instance, such as Monel and Inconel, is used for valves, bolt/nuts, and fittings in semiconductor facility, FCEV(fuel cell electric vehicle) and hydrogen gas station, to reduce the hydrogen embrittlement. Powerful drawing system with worm shaft was developed to manufacture the hexagonal bar using circular bar of Monel material. The objective of this study is to investigate the stability of worm shaft, which is one of important parts in drawing system, from twisting moment and bending moment, respectively. As the results, according to increase of twisting and bending moments, maximum stress was linearly changed, on the other hand, the safety factor was decreased with quadratic curve. Finally the worm shaft was safe until about 25.5 kgf·m for twisting moment and about 2 Ton for bending force which leads to bending moment, respectively.

There is a great deal of research into operating unmanned underwater vehicles (UUVs) from unmanned surface vehicles(USVs) to perform underwater exploration missions in a wide range of ocean environment and at low cost without putting in manpower. A critical component for achieving this goal is the implementation of an automatic launch and recovery system (LARS) that facilitates the deployment and retrieval of UUVs from the USV. This study deals with the design and simulation of a launch and recovery system for the operation of UUVs on the bottom of an USV. The mechanical aspect of the LARS can be developed using various mechanisms; in this study, the Sarrus mechanism was applied to achieve the vertical movement required by the system. The structural analysis of the designed LARS confirmed its reliability and effectiveness for operation in marine environments. In addition, a hydraulic system was applied to operate the LARS, and the overall hydraulic system was designed by calculating the capacity of each hydraulic actuator. And the electrical and electronic system was designed for operation of the hydraulic system.

In this study, an environmental impact assessment was conducted for remanufactured large machine tools. The differences in effect depending on remanufactured products, new products, and remanufactured range was compared and analyzed from an environmental perspective. Remanufacturing was performed on a roll grinding machine and the environmental load generated during the process was collected. Through this, an environmental impact assessment was performed in three scenarios : new product, general remanufactured product, and performance-improved remanufactured product, and the results were compared. A life cycle assessment was performed in accordance with the environmental product declaration’ s common guidelines using the ezEPD program. As a result of comparing the general remanufactured product with the performance-improved remanufactured product, the environmental impact increased as the input raw materials increased in the pre-manufacturing stage, while the environmental impact in the use stage decreased due to the impact of improved energy efficiency. So it was found that the performance-improved remanufactured products have an environmental reduction effect of more than 9%. In other words, if energy consumption during use can be reduced by expanding the scope of remanufacturing and improving performance, the resource saving effect will be reduced, but better environmental improvement effect can be obtained from an environmental perspective.

This paper proposes a method for stator resistance estimation during alignment operation through analysis and compensation of voltage distortion caused by inverter nonlinearity and switching frequency. Stator resistance estimation information is used for sensorless control and winding temperature estimation, which affects control performance and safety. A stator resistance estimation method is needed for motor that cannot measure stator resistance or have a structure that does not allow installation of a temperature sensor. In this paper, we present a stator resistance estimation method by measuring and compensating for voltage distortion components caused by nonlinearity of a three-phase inverter. The effectiveness of the proposed stator resistance estimation method was verified through the several experiments.

Road infrastructure development is an important issue closely related to national competitiveness and the people's quality of life, however the problems of cost overruns, schedule delays, and benefit shortfalls are persistent and recurring. These cost/schedule efficiency issues are acting as obstacles to securing legitimacy when promoting road projects, however the analytical approach from the perspective of post-construction evaluation is still limited. To address the above issues, this study analyzed the relationship between the performance and efficiency of highway construction projects. To this end, this study conducted a correlation analysis between the project performance (project unit cost, project cost growth, project unit schedule, project schedule growth) and project efficiency (demand achievement, difference in benefit-cost ratio (BCR)) metrics for 33 large-scale highway projects. The results indicate that (1) in projects with long road lengths, the project unit schedule and demand achievement are relatively positive; (2) in projects with high project unit costs, the project unit schedule is relatively long, while the project cost growth and demand achievement are positive; (3) in projects with high project cost growths and long project unit schedules, both demand achievement and difference in BCR are relatively negative, requiring systematic project management. These findings not only quantitatively demonstrate that performance and efficiency aspects vary according to the characteristics of highway projects, but they can be used as reference data for planning, promoting, and monitoring future projects.

This study was to investigate the relationship between nurses' self-leadership, empowerment, and patient-centered care and to identify the factors affecting nurses' patient-centered care. Data was collected from 146 nurses at D metropolitan general hospital through a questionnaire from May 2, 2023 to May 20, 2023. The analysis of the data consisted of descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient, and multiple regression analysis. The results showed that self-leadership appeared a significant positive correlation between empowerment (r=.59, p<.001), patient-centered care (r=.61, p<.001), and empowerment showed a significant positive correlation between patient-centered care (r=.64 p<.001). In addition, the factors influencing the patient-centered care of the subjects were empowerment (β=0.42, p<.001), and self-leadership (β=0.34, p<.001), and the explanatory power of these variables was 47.2%. Therefore, in order to promote patient-centered care for nurses, it is necessary to develop various programs that can promote self-leadership and empowerment suitable for hospitals and to make active use of them.

The objective of this study was to evaluate the properties of composite materials manufactured by combining a hardener with a glass ball additive. Throughout the research process, the proportion of the glass ball was adjusted, and its effects on curing temperature, viscosity, bubble formation, and fracture behavior were experimentally analyzed. The results indicate that as the glass ball content increased, bubble formation also increased, impacting both viscosity and curing characteristics. These findings provide valuable data for optimizing the buoyancy and density of composite materials. Additionally, tensile and compressive strength measurements were performed and compared with the strength specifications of commercial buoyancy materials, with some specimens demonstrating properties similar to those of commercial counterparts.

Steel gratings are continuously exposed to vehicle loads and environmental factors, and there is a risk of fatigue failure due to repeated loads. In this study, the nonlinear finite element analysis of steel gratings using Abaqus was used to identify local stress locations, and fatigue life of vulnerable parts was predicted through fatigue analysis using FE-Safe. Based on the research results of this paper, the design of steel gratings can be modified or supplemented to perform optimal design to improve fatigue durability, and it can contribute to improving design standards and establishing maintenance plans in the future.

In this study, we propose a novel 9T dual-port SRAM cell based on FinFET and introduce a design method to maximize energy efficiency. This design can achieve improved power consumption compared to conventional CMOS-based SRAM structures. Specifically, power consumption is reduced by removing the bit line precharge circuit, and an innovative method is introduced to effectively block leakage current occurring during the maintain operation. In addition, the write static noise margin (WSNM) is significantly improved by blocking the back-to-back loop during the write operation. According to the HSPICE simulation results, the proposed SRAM design shows stable performance of about 310 mV and 320 mV in the read static noise margin (RSNM) and WSNM compared to the conventional design, and achieves 55% and 69% improved efficiency in the read and write energy consumption, respectively. This study demonstrates that FinFET-based SRAM cells can be a promising solution for low-power, high-performance memory applications.

The development of ultra-large arithmetic circuits and systems demands innovative solutions beyond conventional complementary metal-oxide-semiconductor (CMOS) technology to enable high-performance digital circuits for nanoscale supercomputing applications. This paper presents a detailed performance analysis of four Full Adders, designed using emerging technologies that utilize between 14 and 28 transistors, each employing distinct logic styles to offer comprehensive insights into their electrical performance. Among the evaluated designs, the Full Adder based on two-dimensional field-effect transistor (2DFET) technology demonstrates the slowest operational speed due to its limited on-current. This limitation arises from the semi-metallic nature of monolayer graphene in 2DFET, which increases leakage current and reduces the on-current. On the other hand, the Full Adder utilizing carbon nanotube field-effect transistor (CNTFET) exhibits a significantly lower delay compared to the 2DFET-based counterpart. Meanwhile, silicon-based Full Adders employing FinFET (Fin Field-Effect Transistor) and silicon nanowire field-effect transistor (SiNWFET) technologies achieve optimized performance in terms of delay, power consumption, and energy efficiency. All simulations were carried out using the HSPICE tool.

This paper discusses the characteristics and key issues in the field of wireless power transfer, analyzing the suitability of resonant circuit topologies under misaligned resonant conditions through bandwidth. It presents the fundamental theory of resonant circuits, along with impedance matching calculations for different topologies. Additionally, the paper examines the characteristics and major issues in wireless charging applications, such as electric vehicles and implantable medical devices, proposing interpretations under misaligned resonant conditions. Finally, bandwidth analysis through simulations is conducted to assess the suitability of various topologies for different applications, which is subsequently validated through measurements in the designed circuits.

Recently, due to the expansion of the ESL and e-book markets, there is a demand for colorization of electronic paper displays. Accordingly, the panel conditions for colorization of the barrier-type electronic paper panel are presented. The cell sizes of the fabricated panels are 100 ㎛ × 100 ㎛, 150 ㎛ × 150 ㎛, and 200 ㎛ × 200 ㎛, the spacing between the lower electrodes is 10 ㎛, 15 ㎛, and 20 ㎛, and the cell gap is 25 ㎛, 30 ㎛, and 35 ㎛ for each cell size. From the electro-optical characteristic evaluation, the reflectivity is better when the cell size is smaller in the panel with the same electrode spacing. It is confirmed that the mixing phenomena of particles in cell is reduced as the electrode spacing increases under the condition that the capacitance is secured. The experimental results show that the reflectivity is relatively high when the electrode spacing is 15 ㎛ and the cell size is 100 ㎛ × 100 ㎛. Stable single colorization is confirmed from the micrograph of the panel image.

This is a numerical analysis study on the case of operating a wall-mounted air purifier in an elevator cabin. Through the numerical analysis, the researchers compared the flow fields when only the air purifier is in operation and when the air purifier and ventilation fan are in operation at the same time. The results of the numerical analysis are as follows: In order to figure out the flow field inside the cabin when operated with the existing ventilation fan, a flow analysis was carried out. As a result, the flow field inside the cabin was relatively more complex than when operated with the ventilation fan and when only the air purifier was operated. In particular, the influence of the ventilation fan discharged from the top became a barrier to the uniform formation of the flow field inside the elevator cabin. Therefore, it is believed that it would be advantageous to operate only the air purifier in order to form a uniform flow field.

This study investigates the restoration and regeneration of damaged quill rods used in roll grinding machines, which are essential in large-scale steel manufacturing processes. Due to continuous wear and tear during operation, these components require effective remanufacturing solutions to restore their functionality. To address this, finite element analysis (FEA) was employed to evaluate the structural integrity and safety of various welding paths used in the restoration process. The results demonstrated that the transverse welding path reduced stress by 6.4% compared to the longitudinal path, making it a more effective method for enhancing the strength of the component. In addition, thermal analysis was conducted to assess the heat impact during the welding process, predicting an increase in hardness of 10.5% in the welded area. The optimized restoration process was successfully applied to quill rod specimens, confirming its effectiveness in extending the service life of roll grinding machines. This remanufacturing technique not only prolongs the lifespan of critical industrial equipment but also offers significant environmental benefits by reducing the need for new parts and lowering manufacturing costs. The findings highlight the importance of sustainable practices in industrial machinery maintenance.

This paper considers the concurrent analysis method with conceptual design and economic feasibility to support the commercialization of oscillating wave power generation systems. A power generation system using renewable energy must have economical design concept for project financing. Economic analysis within similar designs are possible when there are many reference data. However, In cases where reference data are insufficient, such as wave power generation system, the economic analysis is impossible. To tackle this problem, we have suggested advanced analysis method using digital models that overcomes the limitations of data absence and concurrent analysis method in this paper.

In this study, flow analysis of the filter system was performed for the purpose of obtaining the design reliability of the precision filter system using wedge wires. The reliability of the analysis results was obtained by comparing the test results and theoretical analysis results of three types of small-scale precision filter systems. As a result of the analysis, the pressure losses of each filter system were about 6.6%, 10.1%, and 12.3%, respectively. This result well satisfied the conditions of 20% or less, which is the allowable pressure drop test performance of the filter system. In the case of flow drop, the flow loss analysis results of 80 A, 250 A, and 50 0 A were 3.6%, 3.4%, and 3.3%, respectively, which well satisfied the flow drop test performance allowance criteria of the filter system. The results of comparing the small-scale filter test data with the theoretical analysis results showed that there were some errors, but all the test criteria were satisfied. It is expected that the flow analysis results can be utilized in the design of large-scale precision filter systems in the future.

According to the Korean Climate Outlook Report, during the latter half of the 21st century (2081-2100), the average annual temperature in South Korea is projected to rise by +2.3℃ to 6.3℃ compared to the present (2000-2019), depending on the level of greenhouse gas emissions. The maximum temperature is expected to rise by 2.4℃ to 6.4℃, and the minimum temperature by 2.3℃ to 6.4℃. The average annual precipitation in South Korea is expected to increase by 4% to 16% compared to the present, while the number of rainy days is expected to decrease. These climate changes will significantly impact the weathering of rocks. Rock weathering is the process by which surface rocks break down in place due to natural factors (groundwater, running water, wind, glaciers, etc.) and human activities. Weathering includes physical weathering and chemical weathering. Physical weathering causes rock disintegration, while chemical weathering decomposes rocks into fine, different materials. In most cases, both weathering processes occur simultaneously, with their relative importance varying depending on rock type and natural conditions. This study aims to understand the weathering sensitivity characteristics of clastic sedimentary rocks such as sandstone and shale distributed in the Goseong region of Gyeongsangnam-do. The physical and physical properties were assessed through chemical and physical weathering sensitivity tests. The collected rock samples were analyzed using XRD, XRF, slake durability tests, expansion tests, and freeze-thaw tests to determine the weathering sensitivity characteristics of the rocks.

This study evaluates the feasibility and effectiveness of using Ground Penetrating Radar(GPR) mounted on drones to explore buried cultural heritage in intertidal zones. GPR is a non-destructive tool that emits high-frequency signals to detect the location and depth of subsurface structures, proving particularly useful across diverse geological environments. Traditional cart-based GPR equipment has limitations in intertidal areas due to irregular terrain and restricted water depths. However, drone-mounted GPR substantially reduces accessibility constraints, allowing for more flexible and efficient surveys. In this study, GPR equipment was mounted on a drone and deployed over actual intertidal heritage sites and areas where artificial artifacts were buried. The results showed high reliability in well-drained environments, accurately detecting large artifacts such as iron pots and pottery, and also demonstrated the potential to locate smaller artifacts using high-frequency GPR. Additionally, this non-destructive approach enables the prediction of artifact locations prior to excavation, facilitating effective selection of excavation targets. In poorly drained areas, however, the high dielectric properties of seawater weakened the signal, reducing detection accuracy. To address this limitation, improvements in resolution and frequency range may be needed. In conclusion, drone-based GPR presents promising potential as a non-destructive tool for buried heritage surveys in intertidal zones, contributing to enhanced survey efficiency and cultural heritage preservation.

Irrigation and drainage are critical to the growth of field crops and are closely related to soil temperature. Therefore, accurate soil temperature prediction is crucial for precise irrigation and drainage of field crops. This study utilized the following machine learning regression algorithms in Python: linear regression (LR), decision tree (DT), random forest (RF), and support vector machine (SVM). Soybeans were grown in a sandy loam soil and moisture content and temperature were measured at different soil depths during the growing season. Ambient temperature, humidity, rainfall, and radiation were also measured by using a weather station. The soil moisture content and weather data were used in the machine learning program to predict the soil temperature. The RMSE of LR, DT, RF, and SVM were 1.566, 0.579, 0.394, and 0.615, R² was 0.741, 0.953, 0.988, and 0.969, respectively. RF had the lowest RMSE and the largest R². RF was more accurate than other techniques because it was trained on multiple decision trees. As the soil depth increased, the soil temperature variation was less and the influence of the ambient temperature was decreasing significantly. Predicting soil temperature using machine learning could be useful for precision irrigation and drainage.