Earticle

In this study, the design of fuel tanks for SUVs (sports utility vehicles) was dealt with through structural analysis. Fuel tank analysis was performed to evaluate safety, and improvement plans for weak areas were found and reflected in the design. In addition, strength analysis and pressure analysis were performed in parallel to solve the problem of oil leakage around the lower part of the fuel tank and the rear mounting that occurred during the endurance test, and the analysis results were reflected in the design. As a result of analysis through various design changes, it was possible to present an appropriate reinforcement flange shape. In addition, when the thickness of the fuel tank was changed from 1.0mm to 0.8mm, the stiffness of the fuel tank decreased by approximately 30%, and reinforcement was required.

Carbon steel pipes, which are essentially used in the manufacturing industry, are used in various fields due to the advancement of the industry, and a cutting process is essentially applied to pipes manufactured in a nominal size. The cutting process is the most basic and first process used to obtain a material in a desired shape, and it can affect the quality of subsequent processes such as welding or painting, so high-quality cutting surfaces are essential. Therefore, due to the advantage of improving productivity, it is essential to study to secure the appropriate quality of the cutting surface of the plasma cutting process, which is widely used in the industrial field. In this study, the effect of cut surface quality according to process parameters in the plasma cutting process for carbon steel pipe materials was analyzed. The surface roughness was measured to determine the quality of the cut surface, and the relationship between the surface roughness and the process variables was confirmed by selecting the arc current and cutting speed, which are identified as the main factors forming the surface roughness, as process variables.

In this study, the safety aspects were studied by comparing the charge control characteristics of the two vehicles when a failure occurs between the OBC including the charging port or the charging door module (CDM) during slow charging using the In Cable Control Box (ICCB) for a long time.When the AC terminal was momentarily disconnected during charging, the Model-3 vehicle was charged normally if the AC circuit was disconnected up to three times, and the charging control was stopped when the number of disconnects reached four times. However, in the Ioniq-5 vehicle, charging control was normally performed when the disconnected AC circuit was normally connected regardless of the number of disconnection.

In this study, we present an algorithm for indoor robot position estimation. Estimating the position of an indoor robot using a fixed imaging device obviates the need for complex sensors or hardware, enabling easy estimation of absolute position through marker recognition. However, location estimation becomes impossible when the device moves away from the surrounding obstacles or the screen, presenting a significant drawback. To solve this problem, we propose an algorithm that improves the precision of robot indoor location estimation using a Gaussian Mixture Model(GMM) and a Kalman filter estimation model. We conducted an actual robot operation experiment and confirmed accurate position estimation, even when the robot was out of the image.

With the development of drone technology, drones are being used in various industries. In general, drones use lithium-based battery pack, which is sensitive to external impact and temperature characteristics. Therefore, in order to prevent this problem, a battery case for protecting the battery from the outside is used. Usually, carbon fiber is used as case material, carbon fiber is expensive and has disadvantages of being difficult to manufacture. In this study, a battery case was fabricated to minimize the influence of external impact and temperature by using expanded polypropylene material, and also the battery efficiency test was performed using fabricated case. After basic design for battery case was conducted, a system capable of maintaining temperature was constructed by attaching a surface heating element inside the case, and the effect of maintaining temperature according to the presence or absence of the case was confirmed. Using manufactured prototype case, flight tests were carried out to check the battery voltage level according to the presence or absence of the case and to analyze the effect of improving the battery efficiency for the flight time of the drone.

The compressor of a refrigerator accounts for approximately 60-80% of the total energy consumption necessary for the refrigeration cycle. This study investigates the implementation of a pre-compression system featuring a vibrating nozzle, with the goal of enhancing the efficiency of a linear compressor. By utilizing this pre-compression system, the cooling capacity and efficiency of the compressor are expected to improve. The numerical results show that the pre-compression system leads to an improvement of approximately 1.7% in cooling capacity compared to the baseline model. Furthermore, an increase of approximately 0.1 in EER was observed, confirming the feasibility of incorporating a pre-compression system with a vibrating nozzle.

Demand for research on the use of hydrogen, an eco-friendly fuel, is rapidly increasing in accordance with global environmental problems and IMO environmental regulations in the shipbuilding and marine industry. In the case of hydrogen, similar to liquefied natural gas, it has a characteristic that its volume decreases hundreds of times during phase transformation from gas to liquid, so it must be stored in a tank in the form of liquefied hydrogen for transport efficiency. The material of the liquid hydrogen tank is selected in consideration of mechanical properties and hydrogen embrittlement at cryogenic temperatures. In this study, welding research was conducted on STS316L material, which was most commonly used in the space industry. In this study, flux cored arc welding was performed under 4 welding conditions to derive the optimal welding conditions for STS316L material, and then mechanical properties of the welded part were compared and analyzed.

Failure diagnoses on large diesel engine are commonly detected when a deviation or fluctuation in its temperature, pressure, vibration or noise set parameter limits arises. These parameters can be easily monitored and can provide information of the engine’s present state depending on external environment and operating conditions. On the other hand, long term monitoring and condition management can be interfaced into the engine’s existing operating system. The approach is seen to keep track of monitored machines’ status using resonance and vibration amplitude. In particular, these signals will be able to identify complex vibration characteristic pertaining to such as engine torque output and support mounts. In this paper, a basic research for large diesel engine diagnosis was carried-out. The failure diagnosis collects and monitors the vibration state time history by using various vibration signals with reference to ISO 13373-1. Further, this monitoring system in the field of large diesel engines has not been applied practically and the results of this study are presented herein.

This paper presents a 1-DOF robot for hand rehabilitation exercises for hemiplegic patients. The robot provides the cylindrical grasp movement, which is one of the dominant Activities of Daily Living. Linkage Sliding Mechanism allows the proposed robot to be a simple and lightweight structure. Motion test for the healthy subjects are carried out to verify the performance of the robot. Consequently, it was confirmed that the proposed robot was suitable for performing hand rehabilitation treatment.

Metal material production process machinery is becoming larger due to the development of industry. Since there are many overseas manufacturers of large machines used in industrial fields, there are limitations in investigating the manufacturer's noise prediction method and measurement method. A noise map was prepared to obtain information necessary for noise reduction and to effectively manage noise companies. It was modeled with the drawings provided to prepare the noise map and the results of the actual measurement of the site. In order to improve the noise environment of workers, there was a noise reduction effect when a soundproof wall was installed between the noise source and the worker's workplace.

In order to increase the usability of PLA in tissue engineering, we tried to improve the hydrophobicity and low mechanical properties of PLA. The basic solutions were prepared by mixing 3, 5, and 7wt.% of PLA in a solution of chloroform and acetone in a volume ratio of 3:1. Several types of nanofiber mats were fabricated using a mixed solution in which 0.5, 1, and 3wt.% of PEO and PVAc, which are biodegradable polymers, were added to these solutions, respectively, through the SBS method. As a result, it was found that when the content of PEO increased, the diameter and surface state of nano fibers became uniform and the water contact angle significantly decreased, but it did not affect the tensile strength. In addition, the hydrophobicity of PLA was improved to hydrophilicity by mixing with PVAc, but the strain was greatly reduced.

In this study, computer simulation of the drawbridge structure was performed to verify the validity of the design and to evaluate its safety. For this, the follower bracket was modeled, and the parts of the follower bracket were connected using 1D elements. The boundary condition applied moments to the rotation shaft of the girder gear in the clockwise and counterclockwise directions, and the connection between the upper parts was modeled using 1D elements to model the bolted connection. In case of rotational shaft deformation, an analysis was performed on the displacement occurring in the structure during the opening/closing operation. As a result of structural analysis of the follower bracket for various cases, the stress at the connection was lower than the tensile strength and yield strength, so it was evaluated as safe. Through this, we intend to use it as a data that can identify anomalies.

Laparoscopy instrument requires blood vessel ligator to prevent blood leakage. Clip ligation device is widely used to prevent blood loss and secure surgical vision by using blood vessel ligator. However, in order to properly install the clip to the vessel ligator and ligate the blood vessel by the ligation machine, the device is properly operated and the parts constituting the jaw areas should be ensuring sufficient strength and rigidity during the operating. Therefore, the clip binding forces were calculated through a dynamic model of the blood vessel ligator. As a result, the force satisfies the target value of 8.5 N or more regardless of the grip force positions. And structural analysis was carried out to find out the maximum resistance force at the tip of the inner shaft. The maximum load was about 45.6 N, which sufficiently satisfies the development target of 40.0 N or higher.

Aluminum material, which has excellent corrosion resistance, durability, and light weight, is widely used in the field of shipbuilding, and welding is an essential technology in shipbuilding. currently, welding is efficiently used to assemble structures of various sizes in the shipbuilding process, but aluminum is a very sensitive material at high temperatures and in a molten state, so appropriate process control is essential. research on aluminum welding has been continuously conducted, but most of the research is on the butt welding method. therefore, in this study fillet welding experiments, which are essentially applied to the internal structure of aluminum ships, were performed and the correlation between welding beads and process variables was identified. for the welding experiment GMA fillet welding was performed on Al5083 material used in the shipbuilding industry, and the influence of the process variable was confirmed by analyzing the correlation through the analysis of the etched fillet weld bead cross section for the test result according to the process variable.

The fuel oil used for ships has the viscosity higher than the fuel used for general vehicles and contain impurities, so it’s exhaust gas results in the environment pollution. There have been studies actively conducted to examine alternative fuels for improving the quality of the marine fuel oil. It is, however, necessary to test the quality of fuel for mega ships, by conducting the simulation test using reduced-size models, before the demonstration step, because it takes too much cost and time to directly perform the demonstration of alternative fuels. This study, therefore, developed a 30-liter small-size boiler similar to the ship system and performed an initial fuel test by applying MGO to it. The findings show that the amount of nitrogen oxide to which 4% of the standard oxide level was applied was about 24.69ppm, when the oxide level was 10.02%, with the CO2 of 8.02%, the exhaust gas temperature of 291.15℃ and the combustion efficiency of about 74.53%, indicating that it will be necessary to conduct various studies through the ratio control in the future.

3D printing is widely used in product development and prototype manufacturing, and is expected to become universal across various industries with the development of 3D printing-related technologies. However, parts made by Fused Deposition Modeling(FDM) 3D printing using the commonly used stacking manufacturing process, show low tensile strength and hardness. The decreased mechanical properties of these parts limit their use as structural elements. In this study, we aim to investigate the relationship between ultrasonic treatment of PLA parts produced by FDM 3D printing and their mechanical properties. Specifically, we analyze the effects of ultrasonic annealing on the mechanical properties of PLA parts using the tensile test specimen.

In this study, we performed thermal safety design of the electric module of a heat-loaded equipment with consideration of its heat dissipation performance. Initially, we calculated the heat dissipation of natural convection to choose a cooling method. Based on this, we found that some modules required forced convection and selected an air-cooling method with an outdoor temperature of 43 degrees Celsius, which is the maximum temperature in Korea. Prior to module production, we performed thermal analysis of each module and proceeded with a design to increase the thermal conductivity of the module as a primary step, and subsequently proceeded with Heat Sink design to maximize the heat dissipation performance. After considering various constraints according to the system requirements and designing the cooling path, we experimentally and analytically secured thermal safety at the operating temperature of the equipment.

The need for an intelligent information-based ship accident prevention and control system for various marine accidents is very clearly emerging. As it is a variety of marine accidents, the causes are diverse. Therefore, it can be said that it is very important to prevent these marine accidents and their causes in advance. Therefore, a study was conducted on an intelligent information-based ship safety management decision support system that provides information necessary for decision-making at sea and land through an integrated management device for ships that informs safety-related risks in real-time ship operation. In the future, we intend to pursue the development of a system that can aim for safer and more economical ship operation by linking it to navigation instruments through the evaluation and analysis of AI, IoT, and big data.

Path planning is necessary for mobile robots to perform precise and rapid tasks. A collision avoidance function must be included so that the robot can move safely during work, and it must be able to create an optimal path to reduce work execution time and save energy. In this paper, we propose a smart route generation algorithm that searches for global route with an algorithm that can speed up route search and integrates the TEB algorithm that can search for regional optimum routes in real time according to the situation. The performance of the proposed algorithm was verified through actual driving experiments of mobile robots.

In wastewater treatment, an emulsion polymer automatic dissolving system is used to mix and dissolve the polymer used as a polymer coagulant with water before it is put into the dissolution tank. In this study, a disperser is developed to mix water and emulsion polymer better in the dissolving system. For this purpose, the flow analysis of the three disperser models was performed to select the disperser for the emulsion polymer automatic dissolving system with the best performance. The excellence of mixing was evaluated by grasping the flow uniformity and the vorticit in the disperser, and it was confirmed that the TYPE3 disperser was excellent.

The intermediate shaft of sliding type is assembled with coated shaft joint and tube joint. Since the intermediate shaft plays a role of absorbing displacement change due to vibration, the intermediate shaft must have a sliding force value in an appropriate range. In this study, an intermediate shaft assembly system for post-processing of defective intermediate shafts was developed. The intermediate shaft assembly system consists of a wear count prediction model and an automatic wear system. A wear count prediction model was created with the initial assembly sliding force, quality, and set values. As a result of applying the intermediate shaft assembly device, the sliding force of the intermediate shaft was induced within the set value range. And it was prevented from the intermediate shaft defect and eliminated manual work.

Thin-film shape technology is recognized for its core technology to enhance the technology of LCD, PDP, semiconductor manufacturing processes, hard disks and optical disks, and is widely used to form coated thin films of products. In addition, resistance (electron beam filament) technology for heating is used to manufacture filament for ion implants used in semiconductor manufacturing processes. By establishing an electronic beam filament production system and developing seven specifications of electronic beam filament, it is contributing to improving trade dynamics and increasing exports to Japan through localized media of theoretical imports to domestic companies. In this study, CAE analysis was performed after setting electron beam filament specification and development objectives, facilities and fabrication for electron beam filament production, electron beam filament JIG & fixture design and fabrication followed by electron beam filament prototype. Then, the automation and complete inspection equipment of the previously developed electronic beam filament manufacturing facilities was developed and researched to mass-produce them, to analyze and modify prototypes, design and manufacture automation facilities, and finally, to design and manufacture the complete inspection equipment. In this paper, design and manufacture of electronic beam filament total inspection equipment for mass production were dealted with.

This study deals with improvement plans and application results to improve the safety of secondary batteries and chargers applied to Tactical Multi-band Multi-role Radio(TMMR), a new military communication equipment. Due to the nature of the portable weapon system, the terminal structure and manufacturing process of the battery and charger were improved to strengthen resistance to vibration and shock generated during movement, and the battery structure was partially changed to secure resistance to mechanical shock generated when the charger was coupled. In addition, retrospective application was completed for all secondary batteries and chargers previously delivered for TMMR, helping the Korean military to operate next-generation radios in a safer environment.