Earticle

In this study, the structural analyses were carried out with the old and new wheel models installed at the automotive tires. The stress and deformation at the middle circumference of wheel were seen to be greatest at two models. Also, the stress and deformation were smallest at the edge of wheel. The maximum deformation of the old model B is about five times larger than that of the new model A. The maximum equivalent stress of the old model B can be seen to be twice as large as the new model A. Also, it can be seen that the new model A is more stable than the old model B in terms of strength. It can be seen that the deformation energy of the old model B is 19 times larger than that of the new model A. And it is thought that the new model A is much more durable than the old model B in terms of impact. By utilizing this study result, the stress and deformation are investigated without the strength test of wheel installed at the automotive tire, and the durability can be seen.

In order to satisfy the strengthening automobile exhaust gas regulation and CO2 regulation, the development of eco-friendly vehicles is actively progressing. To cope with these regulations, research on alternative fuel vehicles is being actively conducted. Alternative fuels are one of the best ways to reduce dependence on fossil fuels and respond to emissions and CO2 regulations. Natural gas, one of many alternative fuels, contains methane (CH4) as a main component and has abundant reserves, so it is attracting attention as a fuel that can provide stable long-term supply by replacing fossil fuels. In addition, natural gas has a high octane number, so there is room for improvement in combustion characteristics when used in SI engines, and it has the advantage of reducing harmful emissions and carbon dioxide (CO2) compared to conventional fossil fuels. When using a low-pressure injector in a turbo engine, it is difficult to secure the flow rate of fuel because the pressure difference between the injector and the manifold is small. Therefore, it is necessary to develop a high-pressure injector to improve this. Natural gas is a gaseous fuel and should be developed in consideration of compressible flow, Although the use of a CNG high-pressure injector is required, it is difficult to stabilize the flow due to the Mach disk and shock wave interference caused by compressible flow. If the flow is not stabilized, it is difficult to precisely control the flow. Therefore, it is necessary to develop an injector in consideration of flow characteristics. In this paper, the flow analysis according to the shape change of the injector was conducted to improve the fuel flow rate injected from the 800 kPa high pressure CNG injector.

The bead geometry according to the welding conditions was analyzed through the laser fillet welding experiment of 9% Ni steel, and the relationship between the shear strength and the five bead geometry measured by selecting the main bead geometry of the fillet weld was analyzed. Among the welding conditions, the welding conditions that directly affect the penetration depth are welding speed and laser power, and the working angle and beam position have a great influence on the formation of leg of vertical and horizontal members. The bead shape, which greatly affects the shear strength, is the horizontal member length, neck thickness, and weld length, and has a proportional relationship with the shear strength. As a result of confirming the relationship between shear strength and bead shape through the derivation of the trend line, it was confirmed that the length of the vertical member, whose R2 value was 0.92, was most closely related to the shear strength.

In this study, we studied the method of using general architectural glass instead of using the existing acrylic material for high luminance flat lighting. The flat panel lighting used the side illumination method to increase the ease of installation and aesthetic satisfaction. In general, glass has an amorphous structure with a lower angle of refraction than acrylic, so it is not suitable for use in flat panel lighting as a light guide, but in this study, the role of light distribution characteristics and diffusion patterns in the case of using such a glass light guide. Quantitative simulations were conducted to confirm new possibilities. In the simulation, the backlight estimation method was used, and about 10,000,000 rays were placed within a unit area in order to obtain a result similar to the real thing. As a result of the simulation, the geometry of the diffusion pattern could be specified, and the value of the geometry could be quantified using the ratio of the diameter and height of the pattern. As a result of the calculation, it was found that the maximum amount of light was generated around 75 degrees by quantitatively calculating the ratio and the outgoing light angle at which the maximum value of the outgoing light occurred between 05 and 1.0. As a result of these studies, it was confirmed that it is possible to use ordinary glass at the same time as a transparent window and light-emitting lighting at night.

Using lanthanum zinc oxide (LZO) film with the ion-beam irradiation, uniform and homogeneous liquid crystal (LC) alignment was achieved. To fabricate the LZO thin film on glass substrate, solution process was conducted as a deposition method. Cross-polarized optical microscopy (POM) and the crystal rotation method reveal the state of LC alignment on the ion-beam irradiated LZO film. Between orthogonally placed polarizers, POM image showed constant black color with regular transmittance. Furthermore, collected incidence angle versus transmittance curve from the crystal rotation method revealed that the LC molecules on the ion-beam irradiated LZO film were aligned homogeneously. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were conducted to reveal the relationship between the ion-beam irradiation and the LC alignment. The ion-beam irradiation changed the LZO film surface to rougher than before by etching effect. Numerical roughness values from AFM analysis supported this phenomenon specifically. XPS analysis showed the chemical composition change due to the ion-beam irradiation by investigation of O 1s, La 3d and Zn 2p spectra. The ion-beam irradiation induced the breakage of chemical bonds in the LZO film surface and this occurred surface chemical anisotropic characteristics for uniform LC alignment.

The brake system drives the vehicle by converting the kinetic energy into thermal energy. The heat energy generated during the braking process increases the temperature of the structure. It causes thermal deformation due to overheating and causes cracks, noise, and vibration that degrade performance. However, it is not possible to fundamentally prevent the temperature rise of the brakes. There is a need for research on improving the heat dissipation performance by improving the shape of the brake. Therefore, this study analyzed the concentrated stress caused by overheating of the brake disc. In order to improve the performance of the disk, shape optimization design was performed. For stress and thermal analysis, the analysis was conducted using the finite element program ANSYS Transient Thermal and Structural tools. PIAnO (Process Integration and Design Optimization) was used to perform optimal design. In the formulation of the optimum design, the stress was minimized by satisfying the constraints. This study intends to present a new brake disc model by performing perforated shape and arrangement.

This study analyzes the internal temperature characteristics of heater module using a numerical method when the constant heat flux and heat flux time are applied to the surface heating element. The horizontal and vertical dimensions of heater module are 100mm, and the height is 5mm. The heat flux is 10,000W/m2, 15,000W/m2, and 20,000W/m2, and heat flux time is 5 seconds, 10 seconds, 15 seconds, 20 seconds, 30 seconds and 50 seconds, respectively. When the heat flux time was 50 seconds, the temperature of the surface heating element rose to 120.5°C, while the skin epidermis temperature rose 1.7°C. As a result, the surface temperature of the surface heating element increased greatly in the horizontal direction, while it increased low in the depth direction. This is because the heat conduction of the surface heating element is transmitted in the X-Y plane direction, and the thermal conductivity of the pet(polyethylene terephthalate) film and insulation sheet under the surface heating element is very low. when the heat flux at the surface heating element is 20,000W/m2, the skin's epidermal temperature rises up to 0.82℃ compared to 10,000W/m2 and 15,000W/m2.

In this research, carbon nanotubes(CNT) and graphene nanoplates(GnP) are deposited on the surface of carbon fibers(CF) at once. Investigating the effect between CNT and GnP on increasing the interfacial and mechanical properties of carbon fiber reinforced epoxy composites(CFRP). The cross section of the CFRP composites indicates that the GnPs/CNTs hybrid coating exhibits significantly higher mechanical performance in all coating samples. The interlayer shear strength of the GnPs/CNT hybrid coated CFRP composite was 90% higher than that of the uncoated CF composite. The flexural and tensile strength of CFRP composites using GnPs /CNT hybrid coatings were improved by 52% and 70%, respectively, compared to uncoated CF.

In this paper, the injectors with normal quantity, over quantity of +10%, under quantities of -10% and –30%, were mounted on S-ENG and P-ENG in order to measure the voltage energy, current energy and power supplied to the injectors and the fuel economy under several speed of rpm conditions. The voltage and current energy of S-ENG was greater than P-ENG, and the power of S-ENG was measured and analyzed 4.8 times higher than that of P-ENG at all injectors, and the tendency of carbon dioxide emissions calculated from fuel efficiency measurement results was not significantly affected by the type of injectors, but P-ENG was measured to be slightly affected by the type of injectors. It is assumed that the model year and mileage of the test vehicle affects this tendency.

In this study, in order of to reflect the mold deformation in the injection molding process to design of mold, the mold deformation was analyzed by performing flow and structural analysis. The 5 inch LGP(light guide plate) mold, platen and tie bar were modeled and applied to the analysis. The result of melt pressure from flow analysis was extracted for use as boundary conditions acting on the mold surface in the structural analysis. In order to evaluate the accuracy of simulation analysis results, injection molding was performed under the process conditions of simulation. As a results, the mold deformation during injection molding tends to be similar that of injection pressure, and it is confirmed that it shows the behavior and properties of melt resins. Compared with the simulation and experiment, the error of the maximum mold deformation in the injection phase was 4.20%.

In turbopump type liquid rocket engines, ignition and starting are known to be the most unstable and risky section among all operating sections of the projectile. The operation of the liquid rocket engine is the process of ignition and combustion of the main combustor after the turbo pump is driven into a stable section due to the turbine driving of the turbo pump and the ignition and combustion of the gas generator by the pyro starter. In this process, the driving of related components directly influences each other, so each component must be operated with sufficient reliability. In particular, if the igniter does not supply sufficient ignition energy at a predetermined time, an explosion may occur due to stagnation of the fuel/oxidant mixture, so reliability is more important. In this study, the fracture analysis of the gas generator igniter rupture disk according to the shape was performed using computational analysis. As a result, comparative analysis was performed to obtain the optimal dimensions according to each variable condition.

LNG makes cryogenic conditions, so metals without low-temperature brittleness must be used. The International Maritime Organization (IMO) defines 9% Nickel steel, STS304L, 36% Nickel steel and Al5083 as metals that can be used in cryogenic conditions through the IGC Code. In this study, Al5083-O was studied to minimize welding distortion, and verified through finite element analysis and experiments. The block dumping method, which is advantageous in terms of analysis time and cost, was used, not the continuous heat source method. The constraint models with the thickness direction and the tensile force model were compared with the reference model, it was confirmed that the tensile force model had no significant effect. After verifying through the experiment, it was confirmed that the trend of the finite element analysis model was consistent with the experiment. Through this study, a welding distortion minimization model could be found with the block dumping method. It is judged that simulation of many models through short time analysis will be of great help in the field.

The effect of flow direction on heat transfer in water cooling channel of lithium-ion battery is numerically investigated. Battery Design StudioⓇ software is used for modeling electro-chemical heat generation in the battery and the conjugated heat transfer is analyzed with the commercial package STAR-CCM+. The result shows that the maximum temperature and temperature difference of battery with Type 1 are the lowest because the heat transfer in the entrance region near the electrode is enhanced. As the inlet velocity is increased, the maximum temperature and temperature difference of battery decreases but the pressure loss increases. The pressure loss in Type 2 channel is the lowest due to the shortest channel length, while the pressure loss with Type 3 or 4 channel is the highest because of the longest channel length. Considering heat transfer performance and pressure loss, Type 1 is the best cooling channel.

In this study, we compared of control characteristics at two-stroke marine diesel engine by MAN B&W. It was found that MC and ME type of engine largely divide fuel injection & exhaust valve actuator by cam-shaft controlled and electro-hydraulic controlled. Computer based type of engine ME-B type is only operated exhaust valve by driving camshaft, the fuel injection system is fuel oil booster and ELFI valve by Electro-hydraulic. ME-C type is composed of a multi-way valve or FIVA valve. Therefore fuel injection system and exhaust valve system is operated by Electro-hydraulic. ME type engine was shown that the optimization of the combustion process can be achieved for any load on the engine by Electro-hydraulic control system according to the computer based.

In this study, the fatigue properties of press die steel, such as SKD11, and three high-durability die steel for the cold forming of ultra-high-strength steel sheets are evaluated. Specimens for fatigue, tensile, and hardness tests are manufactured through the heat treatment recommended by steelmakers and ultra-high precision processing. The general mechanical properties and fatigue properties are derived from hardness, tensile, and fatigue tests for four die steel. The tensile and fatigue properties of die steel derived through the tests are compared and analyzed. In particular, the correlation between the fatigue limit and the general mechanical properties such as tensile strength and elongation is analyzed, which allows relational expressions to be obtained through regression analysis. Finally, the study confirms that applying high-durability die steel is necessary for improving the die life in the manufacturing of press dies for ultra-high-strength steel sheets.

In this study, the flow analyses were carried out on three kinds of front wing models. The down forces of front wings which influence the stability, cornering at driving were investigated with three models. At model 1, the maximum pressure shown on the main plate of front wing is 3177.539Pa. The maximum pressures at models 2 and 3 are shown to be 3429.677Pa and 3506.494Pa, respectively. The higher the pressure, the more resistance. So, the lower the pressure, the less resistance the model gets. At model 1, the maximum velocity of stream that flows under the front wing was shown to be the smallest among three models. In case of all three models, the pressure at which the air passes through the front wing is high in the upper part of the front wing. Among three models, model 1 is thought to be the most appropriate model to give the effect of the down force while reducing the flow resistance at driving. By utilizing this study result, the flow velocity and pressure are investigated without the flow experiment at driving due to the configuration of automotive front wing, and the flow resistance can be seen.

Refrigerators used in homes occupy a large portion of the power consumption. In addition, most of the power consumption of the refrigerator is used by the compressor. Therefore, it is necessary to study on the improvement of compressor efficiency to save energy. In this study, the suction system was changed to improve the efficiency of the linear compressor. For this, numerical analysis was performed by linking the 1 dimensional lumped model and the 2 dimensional axisymmetric CFD model. The numerical analysis results were also compared with the experimental results. As a result of the numerical analysis, the model with modified suction system increased EER by about 0.25% compared to the basic model, which was also confirmed by experiment.

As the International Maritime Organization (IMO)'s environmental regulations on ship emissions become strict, the demand for ships powered by Liquefied Natural Gas (LNG) is rapidly increasing worldwide. Compared to other materials, high manganese steel has the advantages of superior impact toughness at cryogenic temperatures, a small coefficient of thermal expansion, and low cost of base materials and welding rods. However, there is a limitation in that the mechanical properties of the filler material are lower than the base material having excellent mechanical properties. In this study, after performing a high manganese steel laser butt welding experiment, the welding performance was evaluated through mechanical property (yield strength, tensile strength, hardness, cryogenic impact strength) tests of the weld. As a result, it was observed that the yield strength and tensile strength of the high manganese steel laser welding part was 97.5% and 93.5% of the base metal respectively. Also the hardness of welding part was 84.2% of the base metal. The cryogenic impact strength of the welding part and the base metal were over the 27J, the level of welding part is 76.1% of the base metal.

The paper studied the climbing structure and magnet selection method of exploration platform utilized for large-scale steel structures such as vessel surface. With respect to wall climbing robots, the study proposed a stable operation structure even in rapid incline change of vessel surface. Since the wheel-based operating method is hard to work flexibly in inclination changes, we employed joints and designed the robot to have a rotation joint in the center. The arrangement of wheels is an important aspect of this structure. Viewed from the side, the robot wheels should overlap with each other to have intersection points. The wheels here are ring-type permanent magnets and serve as a tool of attachment on walls. Based on the conditions identified through formula modeling, we proposed the required magnetic force. Important factors needed for magnetic force setup include platform weight, angle between ground and inclined plane, and friction coefficient. We considered only the required magnetic force for the stable adhesion of circular magnet while making not a separate mention about the necessary force for directional locomotion. The analysis results of ANSYS Maxwell are applied to magnetic attachment. Based on the final analysis results, we built a platform and found it did not slip and stayed attached on steel plate.

Numerical analysis has been carried out to investigate the flow field characteristics for exhaust gas in automobile engine DPF system. The DPF system performance is largely affected by exhaust gas flow while it passes through the complicated geometry of DOC/DPF system, fan shape structure, and perforated can with air for fuel combustion. Hence the characteristics of fluid velocity, pressure, and streamline are analyzed with velocity uniformity in front of DOC and swirl flow near the fan. It can be seen that the velocity uniformity increases with the gas flow rate including flow acceleration near the lower area of the fan. The air flow also influences the gas flow distribution close to the impeller and fan structure with complicated swirl flow. These results are expected to be applicable as fundamental design data for automobile engine exhaust system.

In this paper, the goal is to obtain a dynamic model of a particular system. The system is a combination of a wheeled vehicle(chassis) with a turret rotating in azimuth direction and a gun rotating in a elevation direction. At this time, the motion of the gun according to the shaking of the continuous shot is obtained using the coordinate transformation equation in the azimuth and elevation angle. Also, the dynamic model for the swaying of wheeled vehicle is obtained through the Lagrange’s equation. Through this, we analyze the tumbles of the gun, whiat is the major term, and what dynamics are needed for stabilization control.

This study is a basic study to improve fuel economy and reduce harmful emissions from passenger cars. This study is a basic study to evaluate the performance of fuel oil additives. The performance may vary depending on the type of engine, the region of use, and the driving habits of the user. Therefore, there are many difficulties in carrying out the test analysis by the objective experimental method while maintaining the same conditions. Therefore, this study intends to examine in terms of securing objectivity as a comparative study by the measurement of single user for a long time. As a result, in the case of cars using gasoline engines, the fuel economy tended to a little decrease as the distance-age increased. However, in the analysis of diesel vehicles by year, it increased gradually after the 5th year and the distance-age of 60,000km. And a comparison of the last three years, an increase of about 3.1% from 12.44km /ℓ to 12.82km /ℓ.

This paper reports critical heat flux(CHF) performance on wire heater according to material, thickness, length, cross sectional shape. Water was employed as the working fluid, which was saturated at 1 atm. By comparison of CHF values with difference conditions of wire length, contact resistance inherent in the experimental apparatus could be analyzed, which had made the bias error in many research groups. So, exact value of CHF could be measured, which was consistent with the literatures. The CHF value showed decrease tendency, as the cross sectional area increased and reach to the capillary length of the working fluid. Meanwhile, the effect of thermal properties on CHF was not observed in the experimental cases. This data would be used as a reference data in research field of CHF using wire heater, i.e. reactivity initiative accident(RIA).

In this study, visualization of droplet impact on hydrophobic micro-, micro/nano-textured surfaces and lubricant infused surfaces was performed. Experimental specimens were fabricated using MEMS (micro- electromechanical systems) techniques and droplet impact with pure water was visualized at various Weber number range (2 < We < 200) using a high speed camera at 8000 frames per second. Through this study it was confirmed that, various droplet impact behaviors were appeared as the Weber number was increased and the Weber number at which droplet impact behavior changes was affected by surface characteristics. Particularly, on the lubricant infused surface (LIS) after droplet impact retraction velocity is reduced by the lubricant viscosity effect during contraction process of droplet to improve the droplet deposition behavior on the surface. It was confirmed that droplet break up phenomena caused interfacial instability was slightly delayed on LIS due to the viscous dissipation effect during droplet impact process.

In this study, experiments and simulations were performed for fillet joint friction stir welding according to tool shape and welding conditions. Conventional butt friction stir welding has good weldability because heat is generated by friction with the bottom of the tool shoulder. However, in the case of fillet friction stir welding, the frictional heat is not sufficiently generated at the bottom of the tool shoulder due to the shape of the tool and the shape of the joint. Therefore, it is important to sufficiently generate frictional heat by slowing the welding speed as compared to butt welding. In this study, experiments and simulations were carried out on an aluminum battery housing made by friction stir welding an extruded material with a fillet joint. The temperature of the structure was measured using a thermocouple during welding, and the heat source was calculated through correlation analysis. Thermal elasto-plastic analysis of the structure was carried out using the calculated heat source and geometric boundary conditions. It is confirmed that the experimental results and the simulation results are well matched. Based on the results of the study, the deformation of the structure can be calculated through simulation even if the tool shape and welding process conditions change.

Plastic products molded by injection molding have become an essential element of our lives. In addition, plastics can replace parts that used to be metal in the past. Plastic molded products used as a part of a mechanical system require high precision. At the same time, the appearance quality of molded products is also an important evaluation factor. The appearance quality of a molded product is affected by injection molding conditions, plastic material fluidity, and the condition of the mold surface. In this study, the cause of the short shot of the dog house, which functions to assemble the plastic tailgate parts for automobiles, was analyzed. In order to solve the short shot problem of the dog house, the root thickness of the dog house, injection molding conditions, and fluidity of plastic materials were experimented. Through the injection molding experiment, it was found that when the dog house root thickness was increased from 0.8mm to 1.2mm, the filling amount of the doghouse part increased by 43% in experiment mold. These results were verified by injection molding analysis.

This study is developed a self-propelled Welsh onion harvester to increase farm household income by mechanizing the labor-intensive Welsh onion harvesting operation. In order to evaluate the performance of the developed harvester, the work capacity, damage rate, and harvest rate are investigated for three traveling speed levels (7.3cm/s, 12.3cm/s, 19cm/s). Work capacity is increased proportionally to 1.8a/hr, 3.1a/hr, and 4.9a/hr, respectively, as the traveling speed increased. And the damage rate also is increased in proportion to the traveling speed, and under the same conditions, it is increased proportionally to 2.9%, 3.9%, and 4.4%, respectively. The harvest rate is 100% at all speeds of the Welsh onion harvester. The developed harvester is expected to greatly contribute to improving the cultivation environment of Welsh onion by enabling mechanization of the harvesting operation with the largest amount of labor during the Welsh onion production.

In recent years, on average, 270 domestic marine pollution accidents are occurring a year and especially, damage by oil outflow accidents is extremely serious. These large-scale oil outflow accidents bring about a very huge damage to marine living resources and recovery of nature and it takes a long period of time to restore. Therefore, this study aims to examine the increase in the marine pollution control staff over the last decade focusing on the Maritime Pollution Response Bureau that is an organization affiliated to Korea Coast Guard run by the state and compare the number of marine accidents and marine pollutant outflow. Over the past decade, the pollution staff has increased to 110, which is 30 percent higher than the total number of employees and excepting the large-scale outflow accident of a specific year, the outflow has slowly decreased by nearly 55 percent. Although marine pollution accidents have partially grown, most of them are slight careless faults in small fishing vessels with a weight of 50 tons or under. In conclusion, the increase in the marine pollution control staff has led to the decrease in outflow, which means obviously, increasing the marine pollution control staff has had a positive influence on improvement in marine pollutant outflow.

Metal bodies have generally been produced through machining process, even the smallest parts that are assembled and mounted on the metal body. In this study, we will study the process of manufacturing parts called SIM Tray through compound forging process instead of cutting. The process of replacing a series of SIM Tray production process with a composite forging process by simulating the forming process using DEFORM-3D and making process design, mold design, mold fabricating.

Recently, the annual emission rate of CO2 that is the main reason for domestic greenhouse gases is the third highest globally, which means it is an extremely serious issue. It is considered that these greenhouse gases affect climate changes. Especially, the emissions of CO2 in the fishing industry are nearly 4.11 million tons each year, occupying 0.7 percent of domestic total emissions. Therefore, this study clearly analyzed fuel consumption of major fish species over the recent five years focusing on large purse seines. It was revealed that mackerels occupied 55.7 percent of total fish catches of large purse seines and 57.5percent of total fishing earnings. Also, fuel consumption was 236.62 liters per ton caught and 179.51liters per million won earned.