Earticle

The Z-type spring is a key part of the non-vibration air suspension. The non-vibration air suspension was developed long ago and widely used in developed countries. It has strong durability, provides a smooth ride, protects the vehicle body, and protects luggages from damage in truck. In this study, the structural strength of the Z-type spring was evaluated by computing the maximum displacement and the von Mises maximum stress results from applying the load condition based on the maximum weight of luggage in the rear space of a truck.

The reliability of the lifting system has to be ensured so that heavy cargo is handled safely during loading and unloading. Therefore, the accelerated life test was performed on the lifting bow shackle, which is highly affected by the main failure mode, among the components of the lifting system. Besides, an efficient inspection method was suggested for the preventive maintenance of the bow shackles. The acceleration index and acceleration coefficient of the bow shackles were calculated by using the life data of them. The guaranteed life data of the bow shackle can be used to predict the useful life in industries related to lifting work.

A basic metal deposition experiment for manufacturing aluminum parts was performed using WAAM (Wire arc additive manufacturing), and the cross-sectional shape of the laminate according to nine deposition conditions. The effect of heat input was analyzed for the bead shape according to the deposition conditions, and the deposition efficiency was calculated by analyzing the cross-sectional shape of thin-wall parts made of aluminum. The amount of heat input was used in the experiment from about 2.7 kJ/cm to 4.5 kJ/cm, and the closer the heat input was to 4.5kJ/cm, the higher the deposition efficiency was. The maximum lamination efficiency obtained through this study reached 76%.

In this study, the structural analyses were conducted for each model by applying the loads into the design of a large commercial truck seat. Model C with three vertical frames has the smallest total deformation among all models, indicating the strongest stiffness. The maximum total deformation of model C was shown to be 0.68 times smaller than that of model A and 0.79 times smaller than that of model B. The equivalent stress of model C was also shown to be the lowest, indicating the greatest stiffness. The maximum equivalent stress of model C was shown to be 0.8 times smaller than that of model A and 0.91 times smaller than that of model B. At the upper part of the seat or the part where the force was applied, all three models were shown to have the largest total deformations and equivalent stresses. If the result of this study is applied to the design of automotive seat frame, it is thought that the durable and rigid sheets can be manufactured efficiently. By utilizing this study result, the equivalent stress and total deformation are investigated without the real experiment by shape at the seat of large commercial truck, and the durability and rigidity can be seen.

This paper is about the selection of the optimum position of the driving system and the analysis of the load at that position in order to safely drive an object with heavy load on the turret with a linear actuator. Usually, linear actuator is required the greatest force when first lifting or pushing a structure, and it is determined by the initial angle and positions. After all, the optimal position of the linear actuator in a limited turret space is closely related the required load and driving performance of the linear actuator. Therefore, this paper contains the contents of securing the driving stability and performance at optimum position on the turret by considering the two cases of linear actuator position arrangement.

Various underwater studies using underwater sonar sensors are actively in progress. However, unlike the ground, the underwater has a lot of noise. So it is difficult to accurately recognize the underwater environment. The final purpose of this study is to improve the efficiency of the underwater environment recognition using the underwater sonar sensor by developing a filtering algorithm that removes noise and expresses the object from the underwater sonar image captured by the underwater sonar sensor. To develop a filtering algorithm, convolutional calculations were used with three types of filters. This paper is about the case study that conducted to set the parameters of ‘Gabor Filter’ suitable for underwater sonar image during the design process of filtering algorithm. As a result, it was possible to find the most suitable ‘Gabor Filter’ parameters for underwater sonar images. And it showed high accuracy with a binary map of obstacles created by hand using the naked eye. Through this study, it can be utilized not only as a binary map of real-time obstacles, but also as an algorithm for generating object masks in underwater sonar images for deep learning.

There are many disadvantages to existing silencers used in power plants. Recently, high-performance silencers are required in society, so it is necessary to develop silencers accordingly. Therefore, in this study, to develop the flow silencer by taking advantage of the foamed aluminum, the property values such as loss coefficient and porosity were obtained through experiments, based on the Forchheimer's law. CFD analysis was performed by applying a porous modeling technique to foamed aluminum and the results were compared with experimental values. The error rate between the results of the experiment and the flow analysis is within about 2.79%, so the results of the experiment and the analysis agree relatively well. When the foamed aluminum was installed, the flow noise was reduced by about 5.14dB.

The method of evaluating the forming limit of sheet metal is using the forming limit diagram(FLD), and the test method for measuring forming limit curve(FLC) is ISO standardized. On the other hand, in the case of metal bulk materials, it was confirmed that the forming limit was defined by using various predictive models based on the ductile fracture theory. However it did not show a constant forming limit (limit damage value) depending on the shape of the specimen. Therefore, a study was conducted on the derivation of the triaxial stress curve to predict the fracture of the material for various stress triaxiality, not the existing limit damage value.

The performance of ground-based optical structures is highly sensitive to external environments, such as airflow in open space. In this paper, initial aerodynamic data due to ambient air flow were analyzed in optical models designed through knowledge-based design algorithm, and dynamic data acting on optical structures in turbulent flow with velocity of 50m/s were analyzed to present the initial shape design conditions of the structures. The simulation results showed that the maximum pressure, minimum pressure, and maximum differential pressure acting on the mirror are directly proportional to the sweep angle.

The temperature distributions were numerically calculated for the two-dimensional transient conduction heat transfer problem of a square plate. The obtained temperature distributions were converted into colors to create images, and they were provided as learning and test data of CNN. Classification and regression networks were constructed to predict representative wall temperatures through CNN analysis. As results, the classification networks predicted the representative wall temperatures with an accuracy of 99.91% by erroneously predicting only 1 out of 1100 images. The regression networks predicted the representative wall temperatures within errors of C. From this fact, it was confirmed that the deep learning techniques are applicable to the transient conduction heat transfer problems.

Spot welding is a representative process in automotive welding and the application of intelligent systems is accelerating. In particular, in the case of welding electrode management, the timing of electrode wear and dressing was determined by continuous spot welding evaluation, however there is concerned that errors in welding equipment or processes may work in a complex manner. In this study, a dynamic resistance waveform sensing and image measurement system that greatly affects the nugget formation, which is important to the quality of spot welding, was fabricated and used. Based on the experimental data of the galvanized steel sheet, an electrode life prediction algorithm for electrode wear was derived through CNN(Convolutional Neural Network) model of machine learning training.

This paper reports slug bubble dynamics on modified surface with two-dimensional graphene film in downward-facing nucleate boiling. Behaviors of slug bubbles were observed with high speed camera, and post-processing was followed to measure departing speed, frequency, and diameter of slug bubbles, which were important to analyze boiling performance change. The graphene-modified surface showed enhanced boiling heat transfer coefficient (BHTC) and critical heat flux (CHF). The effect of surface modification on slug bubble dynamics was quantitatively analyzed; bigger slugs departed from the modified surface with faster speed but same frequency, compared with the bare. It seems that the BHTC enhancement is caused by increase of bubble diameter, resulting in increase of its departing speed. The higher speed of departing bubble could extend the hydrodynamic limit of vapor removal from downward-facing surface, so that CHF performance could be enhanced.

In this study, four types of water-heavy fuel oil hybrid emulsion oil were manufactured depending on the moisture content ratio in order to reduce exhaust emissions of heavy fuel oil(Bunder-C), which is necessarily used in vessels, power plants and boilers. The components of the manufactured emulsion oil were analyzed using the ISO standard testing method. The analysis result showed that in the EM25 fuel with a maximum moisture content ratio of 25.0%, the moisture content was 25.0%, the sulphur content was 0.20%, the kinematic viscosity was 144.8mm2/s, the specific gravity was 0.9382, and the flash point was 100 Celsius degrees or above.

Experiments were conducted to evaluate the performance factors such as type of working fluid, flow direction, arrangement and stage of loop thermosyphon heat exchanger for ESS battery container cooling. Pentane showed slightly better performance of the heat exchanger than R-134a as a working fluid. Driving the fan in the suction direction showed improved performance compared to the blowing direction. The two-stage heat exchanger increased the heat transfer rate by more than 30% at the same temperature difference compared to the single-stage heat exchanger. Also, the counterflow flow showed better performance than the parallel flow in the two-stage heat exchanger.

In this study, the failure characteristic of the center floor of a front-wheel drive vehicle was investigated according to material. UHSS, Al6061-T6, CFRP, and CFRP-Al were used as materials. As the analysis condition, a fixed support was applied to the rear surface of the center floor and a forced displacement of 2 mm/sec was applied to the front surface. As the result, when comparing with the equivalent stress and strain energy according to the material, it was found that UHSS, Al6061-T6, CFRP, and CFRP-Al were higher in the order. Also, when comparing with the equivalent strain due to the material, it was shown that the equivalent strain was high in the order of Al6061-T6, UHSS, CFRP and CFRP-Al. As for the damage characteristic of the center floor according to the material, it was found that the highest structural stability was obtained when UHSS was used. However, it was found that it was good to utilize Al6061-T6 in order to acquire the structural stability along with the structure with the lighter weight.

In the manufacturing industry, sparks occur during operation due to collisions of metals, and strong sparks and arcs are generated even during welding works. X-rays are generated when high-speed electrons from outside collide with electrons in a metal. Thus, the objective of this study proposes the risk of sparks and arcs that can generate X-rays. We developed the spark generator using the electrostatic principle and constructed the arc generating device using the high voltage. The X-rays are measured when sparks and arcs are continuously generated between the anode metal target and the cathode metal. The measured X-rays were found to be harmful to humans when exposed for a long period. Therefore, workers exposed to workplaces with frequent sparks and arcs need to protect themselves.

Robots for a wide range of purposes have been developed along with the rapid industrialization. On the basis of higher convenience, the robots have been creating new industrial environment. The robots are generally classified into service robots and industrial robots. Robots in various shapes have been developed on the basis of the autonomous mobile robots. The autonomous mobile robots have the possibility to crash against any object in their moving range. This paper suggests a collision avoidance method to prevent collision of robots. The collision avoidance method analyzes the road context data and makes a robot move to a safe area. The collision avoidance method proposed in this paper converts the road context data into the information value. The collision avoidance method analyzes the present risk on the basis of the converted information value. The collision avoidance method makes a robot move to a safe area when crash is estimated by the information analysis.

In this study, a smart skin system that combines SPD (suspended particle display) and LGG (Lighting Guide Glass) and its optimal control method was developed for the purpose of simultaneously reducing the lighting load and cooling load in office buildings. And a demonstration site was built to test the results. The demonstration site was constructed as an experimental group with a smart skin system installed and a control group with a general window system installed. When the cooling energy consumption of the experimental group to which the smart skin system was applied was reduced by about 36.9% compared to the control group, the lighting energy was also reduced by 54.4%.

High-performance vehicles with V6 or higher are designed with a dual exhaust system to satisfy both performance and quietness at the same time, and have a confluence geometry for the purpose of stably maintaining the back pressure inside the pipe. The exhaust system generates noise and vibration under the influence of the rotating engine. In particular, in a state such as idling, vibration occurs in a certain frequency range, which may affect the natural vibration of the exhaust system. Therefore, in this study, the optimal shape is proposed by comparing the ignition frequency calculated based on the vibration measurement result in the idle state and the numerical analysis result.

This study aims to respond to the market of Tata Daewoo commercial vehicles in emerging countries (Southeast Asia) lightweight and cost-saving type for the production of dump trucks with secured price competitiveness requested to develop a square deck, and accordingly. This study is a 15-ton dump modified the reinforcement frame of the side gate to reduce the weight of the new truck model deck. It is designed to maintain the strength of 80% or more of the existing gate by (reducing input material). The system and structure rationalization proceeded.

In the past, the U.S. NRC(Nuclear Regulatory Commission) strictly required testing of the EDG for NPP through Reg.Guide 1.108 Rev 1. However, these test requirements acted as a deterioration and wear factor for diesel engines, and are now applying Reg.Guide 1.9 Rev 3, which relaxed regulatory requirements and improved performance monitoring. After applying the new regulatory guidelines in this study, the EDG analyzed the performance of the combustion chamber. As a result, there were no signs of deterioration or decreased performance of the current EDG. This is due to slow start, short operation time, the use of high quality fuel oil and proper maintenance. On the other hand, if the performance is proven, it is judged that proper period extension of cylinder maintenance is possible.

This study is about the control method of smart skin applying SPD(Suspended Particles Display). Smart skin is a self-developed composite window system for the purpose of reducing the cooling load and lighting load. The simulation by TRNSYS18 was modeled in detail based on an actual office located in Jeonju. The previously studied smart skin control method (case1) is a time-dependent control method, and a new control method (case2) was devised based on the data that consideration of daily insolation is important in an actual environment. As a result of simulation by case1, it was found that the amount of cooling energy and lighting energy saved was reduced by 15.1% and 39.2%, respectively, compared to the general model. As a result of the simulation by case2, it was found that the amount of cooling energy and lighting energy saved was reduced to 17.6% and 57.5%, respectively, compared to the general model. Therefore, the newly proposed control method considering the amount of insolation and time was found to be effective in reducing cooling energy and lighting energy.

The premature failure of the universal joint connecting the drive gear box and the cooling fan caused a deterioration in serviceability and operability. Universal joint is a device that transmits engine power to a cooling fan. Internal pin breakage and shaft separation can cause secondary damage such as cooling fan malfunction and radiator damage caused by component failure. The purpose of this paper is to analyze the damage phenomenon of universal joints caused by bundles in SPVs and to improve them. In order to verify the improvement, a single part test and a system conformance test were conducted, and durability test was conducted to confirm the improvement effect on the improved prototype. Through these, the effects of increasing the durability of the improved product were estimated.

The molybdenum cup and molybdenum pin, which are the main materials of the molybdenum electrode used for the LCD BLU CCFL electrode, have not been developed in Japan and all of them are imported and used from Japan, is giving a competitive burden. In this research, the CCFL electrode of LCD BLU is used to develop the manufacturing technology of molybdenum pin. The development of linear processing technology is used to that. The development of molybdenum wire surface treatment technology is used to that. The development of wire cutting technology is ued to that. The design and fabrication of JIG and Fixture for inspection is used to that. The molybdenum pin prototyping and analysis is used to that and finally, the development of 100% molybdenum pin inspection technology is used to that. In this paper, especially, research on design technology of wire cutting is treated.

This study was conducted to compare the mechanical properties of NAB (Ni-Al-Bronze) material manufactured using WAAM (wire arc additive manufacturing) technology and cast NAB that has been used. Two types of mechanical property test pieces were collected from the deposited bulk NAB material according to the direction of deposition, and compared with each other. As a result of mechanical property evaluation, the deposited NAB exhibited anisotropy according to the direction of deposition, and showed high tensile strength, hardness, and shock absorption in the longitudinal direction of the welding line.

Valves are widely used in various industrial fields, such as plants, vessels and shipbuilding. In particular, the performance of the valve is an important factor that can influence the performance of the entire system. Therefore, in this basic study to establish a national technical qualification in the domestic field of valve maintenance, demands for the fields of valves and major congruence were analyzed focusing on the industrial facility curriculum of Korea Polytechnics, and level-differentiated trial examinations were applied to relevant majors to standardize the developed valve tester. The trial examination result displayed that in the highest level of difficulty, in the medium level of difficulty and in the lowest level of difficulty, the pass rate was 0%, 17.86% and 39.29% respectively.

The battle vehicle has six types of indicators attached to the instrument panel in consideration of the special battlefield environment. However, many problems of moisture occurred during the operation of combat vehicles. These moisture phenomena can adversely affect aesthetics and functionality. Moisture is generated on the instrument panel due to the inflow of external moist air, the desorption of the moist air inside the parts, and the fluctuation of the dew point temperature. In this paper, we try to derive the root cause of various moisture generation and provide an improvement measures for moisture control. Therefore, the failure mechanism of the instrument panel may be analyzed and the design may be changed depending on the failure factor. Furthermore, the effect of the design change is verified, and the humidity performance is evaluated.

The molybdenum cup and molybdenum pin, which are the main materials of the molybdenum electrode used for the LCD BLU CCFL electrode, have not been developed in Japan and all of them are imported and used from Japan, is giving a competitive burden. In this research, to develop the manufacturing technology of molybdenum pin used for CCFL electrode of LCD BLU, development of linear processing technology, development of molybdenum wire surface treatment technology, development of wire cutting technology, production of molybdenum pin, design and fabrication of JIG and Fixture for inspection, molybdenum pin prototyping and analysis, and development of 100% molybdenum pin inspection technology. In this paper, especially, research on prototype manufacturing and CAE analysis is treated.

In this study, analyzed the cause of failure of the cardan shaft for water propulsion of an armored wheeled vehicle. During the development test(DT), the vehicle was deflected to the left on the water. As a result of the confirmation, increasing angular displacement and abrasion of SPIDER(Universal joint) occurred. As a result of a structure analysis and torsion fracture test, cause of failure is not insufficient design and strength deficit of each parts. and as a result of a simulation review of the assembly layout of each part, it was confirmed that excessive rotational vibration occurred. In order to solve this problem, improved the assembly layout of the water propulsion system and the worn SPIDER lubrication. Since there has been no occurrence of the same case between military operations so far, it has been confirmed that the improvement plan is appropriate.