Earticle

The characteristics of pollutant emission for non-premixed flames with LCG 8000 and LCG 6000 represented as low calorific gases were investigated by numerical simulation. Commercial software (ANSYS 16.2 - FLUENT) is used to predict 2-D pollutant emission with GRI 3.0 detailed reaction mechanism. In addition, the addition of hydrogen to LCG 6000 was also considered. As result, the flame length and temperature of LHVGs were decreased with decreasing calorific value at the same condition. In addition, NO concentration was decreased as temperature decreased. However, CO concentration for LCG 8000 predicted to be slightly higher than that for methane due to the high propane concentration. In the case of LCG 6000 with added hydrogen, the flame length was the shortest and NO concentration was the highest due to the highest flame temperature, but CO concentration decreased rapidly due to the addition of the carbon-free fuel.

The purpose of this study was to develop a side protection device for school buses for children. In the case of the door side impact beam, it plays a very important role because it protects passengers from external collisions. However, in the case of a school bus for children, the space between the door and the door trim is very narrow, unlike a general passenger car. So, as an alternative to this, we are trying to develop Rub Rail, which is compulsory for children's school buses in the United States. Based on the results of structural analysis according to the cross-sectional shape of the rub rail, we want to find out the appropriate shape of the rub rail.

In this paper, the mechanical properties according to the rCF weight percent(10, 20, 30, 40, 50wt%) of the rCFRP specimen were evaluated and analyzed. First, to prepare rCFRP specimens, pellets were prepared according to the type of weight percent, and rCFRP tensile specimens according to ASTM D638 were prepared using an injection molding machine. Tensile tests were performed on each of 10 specimens according to weight percent conditions, and tensile strength and modulus of elasticity were calculated. For a detailed analysis of the correlation between the internal structure of the specimen and the mechanical properties, the weight percent to the constituent materials of the rCFRP specimen was calculated using mCT and used for the analysis of mechanical properties. For a more detailed analysis, a detailed analysis of the mechanical properties of rCFRP was performed through the fracture surface analysis of the specimen using FE-SEM.

In the automobile manufacturing industry, lightweight design is one of the essential challenges to be solved fundamentally. The vehicle wheels are classified as safety related components as the main substructure of the vehicle. In this study, we illustrate a technique for selecting the appropriate number of spokes. Based on the basic model of the selected number of spokes, we propose a method to maintain stiffness and design lightweight using topology optimization software. Based on the basic model of the selected number of spokes, it was redesigned to be lightweight while maintaining stiffness by utilizing topology optimization software. By comparing and reviewing the structural analysis results of the basic model and the redesigned model, a design technique that can maintain structural safety and reduce wheel mass was proposed.

This paper developed a wind triboelectric nanogenerator(TENG) using cubic PTFE model. When the wind is injected, the cube PTFE is scattered inside the cylinder TENG structure and energy is harvested. The TENG structure was designed as a cylinder that allows independent dielectric to rotate well inside. In addition, an inlet and an outlet were made to allow good wind flow. Unlike wind harvesters, where one end is mostly fixed and energy is harvested, the dielectric's motion is freed using independent mode. The electrodes and dielectric materials used Aluminum(Al) and Polytetrafluoroethylene(PTFE). The cube PTFE dielectric contacts/separates the electrode attached to the inner wall of the cylinder along the inner wall of the cylinder. At this time, electricity is generated by the kinetic energy generated by the wind. In this study, the efficiency by the number of Cube PTFE inside the cylinder was compared. The experiment confirmed that as the number of Cube PTFE increases, the power increases, but if the number of Cube PTFE exceeds an appropriate number, the density inside the cylinder increases, interrupting the flow of wind, and thus decreasing the power.

Considering the features of body repair for automotive body where same damage and repair conditions does not exist in car accident, it is essential to acquire know-how and continuously approach new materials and new technologies on the site of maintenance where the theoretical instruction of textbook cannot react accurately minute by minute. Especially, in case of car repair from unexpected accidents such as body repair or dent repair, it is difficult to satisfy vehicle owners despite their request. Accordingly, this study researched the better maintenance technology to restore to its original state with more improved technology as vehicle owners wish. This study made time to repair reduced by 98% and the cost reduced by 79.6% through the accurate diagnostic technique before repair and maintenance technologies of body crash analysis applying property of high-speed tensile. It also obtains intangible effects including prevention of environmental pollution and maximization of vehicle owners satisfaction.

This paper proposes a method to improve the position control synchronization performance by synchronizing the controller operation between servo drives based on the synchronization signal of the EtherCAT(Ethernet for Control Automation Technology)distributed clock. In order to synchronize the operation of the controller between the servo drives, the phase of the operating frequency of the PWM(Pulse Width Modulation) module for motor control was synchronized based on the synchronization signal. At this time, the operation sequence of the current, speed, and position controller of the servo drive operating based on the PWM operating frequency was rearranged. Therefore, the servo drives on the network run the same controller at the same time. And the time at which the master's command is reflected to the drive's controller and the time at which the drive's status information is acquired coincided among the drives. After establishing an experimental environment in which servo drives are arranged in the EthercCAT network system, we verified that the position synchronization performance between servo drives applying the proposed method is improved.

In this paper, we propose a analysis of domestic and foreign standards on protecting human body from EMF(Electromagnetic filed) and effect of the human body through EMF analysis of military electronic equipment in operation. We measured the EMF intensity of the side lobe and back lobe main beam on Radar Equipment at an accessible position. As a result, it was confirmed that the measured EMF intensity of three types of radar equipment did not exceed the standard on domestic protecting human body from EMF.

This study investigated variables for improving adhesive strength using laser surface treatment when bonding dissimilar materials using adhesives. adhesive strength analysis was performed for CFRP and Al6061 by laser irradiation intensity, and surface roughness was measured to analyze the related results. In the case of CFRP, the adhesive strength was good when the surface was not treated. In the case of Al6061, the adhesive strength was 25 MPa when the surface was treated with 20W, the maximum output of the laser surface treatment equipment, and the adhesive strength was improved by 125% compared to the untreated specimen. In addition, by measuring the surface roughness in the experiment, it was confirmed that the higher the surface roughness, the better the adhesive strength.

We propose a method for developing an in-pipe inspection robot based on multiple inertial sensors. Estimating the position of underground pipelines where satellite signals do not reach remains challenging. High-precision inertial sensors and high-tech mobile robots can be solutions, but their high price limits their general use. We developed an in-pipe inspection robot by combining various low-cost sensors with a microcomputer-based RC car platform. First, we fabricated a multi-inertial sensors module by combining commercial grade low-cost MEMS inertial sensors. The sensor values measured by the multi-inertial sensor are transmitted to the main computer through the MCU, and the attitude angle of the vehicle is finally calculated through the inverse variance weighted average. The travel distance of the robot is estimated by using hall sensors and neodymium magnets attached to the inside of the wheels. Also, we measured the pipe diameter using multiple ultrasonic sensors. We verified the estimation accuracy of each sensor through experiments and consequently estimated the 3D trajectory of the in-pipe robot.

In this study, when a communication wire harness is defective due to long-term operation of a vehicle with a high-speed CAN communication network, the unique ID information of each controller and the oscilloscope waveform are analyzed to find defects. As a result of the experiment, it was possible to know whether the circuit of the main wiring was disconnected by the differential voltage analysis, and it was possible to confirm whether the sub-wiring was disconnected due to the generation of saw blade waveforms in the bus idle part. In addition, the fault location could be found with controller ID information and communication circuit analysis.

Numerical analysis has been carried out to predict the thermal characteristics for a LED lens in mold core system. These thermal characteristics inside the lens are largely affected by geometry, material, and initial conditions of the mold core and lens system. Local temperature and heat flux variation inside the lens are compared for several initial temperatures. Maximum temperature inside the lens was decreased rapidly from the beginning of cooling process up to about 10 seconds. There was also large variation of the heat flux at the upper and lower surfaces of the lens with initial temperature distribution. And the heat flux from the thin lower surface of the lens was relatively higher than the opposite-side thick region. In addition, overall heat transfer rate from the lens through the mold core has similar transient distribution from the beginning. These results can be applied as basic heat transfer data for the LED lens design and manufacturing process in the mold core system.

In this paper, the mechanical properties of glass fiber reinforced plastic (GFRP) rebar, which has been applied as an concrete reinforcement, and produced carbon fiber reinforced plastic (CFRP) grid were compared to develop a concrete reinforcement material with excellent mechanical properties. In addition, the mechanical properties of CFRP prepared with each molding process were evaluated. Three molding processes were evaluated: prepreg oven bagging, reaction injection molding (RIM), and pultrusion. The tensile strength of the CFRP grid prepared through pultrusion was 2.85GPa, the elastic modulus was 169.81GPa, and the strain was 1.68%, which was 2.85 times better in tensile strength, and 2.83 times better in elastic modulus compared mechanical properties of GFRP rebar. The strain was confirmed to be equivalent to GFRP rebar.

In this research, the a novel finishing machine was used for hight-precision surface of spherical ball products that have been widely used for on/off valve for hydrogen energy flowing system and in medical field such as artificial hip joint component. The spherical balls products are the workpiece that made by Co-Cr-Mo alloys with 32-mm in diameter and Sa≈ 0.30μm in surface roughness. Their surface roughness was successfully improved via the magnetic abrasive tools that controlled the magnetic field of permanent magnets. The critical input conditions were selected as rotational speed: 800rpm, gap: 3mm, tool grain size: 1-μm finishing time: 0, 3, 6, 9, 12, and 15min. The results of this research showed that under the given finishing conditions, the high surface quality in the terms of surface precision of spherical ball products are successfully achieved, in which the surface roughness is reduced from 0.30-μm to 0.04-μm within the short finishing time at 12min. Therefore, it can be concluded that a novel finishing machine is feasible to be used for improving the surface roughness of spherical ball products, resulted in high surface precision of materials.

In this paper, a numerical study was conducted on the development of HVAC(Heating, Ventilating and Air Conditioning) performance required for a large-scale greenhouse. In order to increase the simulation efficiency, fan model, porous media, and radiator model, etc. provided by Fluent were used based on the part performance analysis such as blowing fans and PTC heaters. Developed simulation method was applied to the decision of fan position to secure the flow uniformity and the determination of the heater specification to maintain the temperature suitable for plant growth. This study is the first step for the development of integrated environmental control system of greenhouse for high-income crop cultivation and the simulation method will be revised after correlation test.

The nonlinear simple pendulum is investigated to find the exact closed-form analytical solution, satisfying initial conditions of angular position and angular velocity. While previous numerous studies have been conducted on the nonlinear simple pendulum, the exact closed-form analytical solution still remains not available in public domain for the most general initial condition including initial angular velocity as well as initial angular displacement. In this paper, the exact closed-form analytical solution for the general initial conditions is derived using Jacobi’s elliptic function and elliptic integral. The result was verified by comparing it with previous studies and the numerical solution of the equation of motion through the Runge-Kutta integration method.

Recently, as interest in safe food and ingredient content has increased, the demand for highly concentrated health functional food that can be manufactured at home is increasing. Accordingly, in this study, we developed a galenic maker that can increase the extraction efficiency of herbal medicine(ginseng) ingredients and shorten the manufacturing time. After verifying the safety of the designed components through structural analysis and thermal flow analysis, the dimensions and shape of the galenic maker were determined. A prototype was produced based on the design process and the performance of the product was verified through extraction efficiency and ingredient analysis.

In order to develop greenhouse cooling and water saving technologies suitable for desert climate, the performance evaluation of the cooling packages and condensate water recovery from cooling fan coil unit. As a result of the application for tomato greenhouse in summer, the root zone temperature of root zone cooling+duct cooling case and root zone cooling case was 25℃ during the day and 20℃ at night, which was suitable for tomato growth. When the nutrient solution tank was cooled, the temperature of the nutrient solution was maintained at 20 degrees, but otherwise, the temperature exceeded 30℃, causing the root zone temperature to rise. Condensate water recovery per fan coil unit was 93L on average per day in August, and was proportional to relative humidity in greenhouse and temperature difference between dew point temperature and the surface temperature of heat exchanger. Tomato growth was found to be improved in the order of root zone cooling+duct cooling, root zone cooling, duct cooling and control. It was analyzed that the yield of root zone cooling+duct cooling, root zone cooling and duct cooling increased by 35%, 28% and 11%, respectively, compared to the control.

This study is to develop a radish skin peeling machine. Currently, radish peeling work is carried out manually, so the unit price is high due to the increase in labor cost, and problems related to hygiene continue to occur. To solve this problem, a field supply type radish skin peeling machine was designed and manufactured. The peeling machine is a principle in which the skin is removed by conveying the radish using a roller and passing through a blade assembly. In this paper, the design and analysis of the roller and blade part applied during the movement of the radish were carried out, and structurally stable results were obtained.

A turbo engine is used to improve engine volumetric efficiency by using the energy of exhaust gas with a device such as a turbocharger. Recently, it has been attracting attention as a solution for responding to environmental issues such as exhaust gas regulation, and its use is being expanded to gasoline and CNG engines as well as diesel engines. However, as electric and hydrogen vehicles enter the automotive market more rapidly, traditional turbo engines also confront many challenges. In this paper, to examine the current status and prospects of the turbo engine, we analyze the related patents in the turbo engine field applied to patent offices in seven major countries, including Korea, USA, China, Japan, Germany, France, and the European Union Patent Office, and analyze the patent application trend. Using ‘the pie’ system of Korea Institute of Science and Technology Information (KISTI), family patents were refined, patent application trends were diagnosed, and the technology and market competitiveness of major applicants were compared and analyzed. Even within the turbo engine market, where traditional automakers and turbocharger manufacturer participate, it was possible to examine the dynamic changes in the market through the analysis of technology and market competitiveness. The main companies leading the technology and market aspects and the companies specialized in the technology and market aspects were observed.

Recently 3d printer industry has two demands. first is color 3d printing. second is mass production using 3d printer that has large bed. According to previous studies, 3D printed objects have different weights depending on filament colors. 3D printed tensile specimens with filaments of various colors were checked to see they had the same weight. If so, we wanted to see it was statistically significant. As a result, we found that the weight of 3D printed objects was statistically significantly different depending on the filament color. The average weight of 3d printed objects is: Black(8.63g), Blue(8.58g), Yellow(8.53g), White(8.48g), Natural(8.46g), Green (8.45g), Red(8.42g).