• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.300-303
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• 2010

This work shows the result of numerical simulation on a reacting flow by varying atomization properties which can be obtained from a injector for a small and low power aircraft gas turbine engine. Because the atomization properties mainly affect on the performance of the engine, a lot of efficiency tests are needed when a new injector is developed. Nowadays researches has been actively performed using computational analysis. Using commercial package CFD-ACE+, basic studies on the reacting flow field have been conducted. Those results show that the reaction rate is increased when higher pressure and wider angle spray condition are used. More smaller parcels can also enhance the fuel-air reaction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.95-98
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• 2010

A multi-injector rocket engine using high concentrated hydrogen peroxide and kerosene as the oxidizer and fuel was designed and fabricated. Six coaxial swirl injectors were mounted on the mixing head and flow analysis in the manifold was performed to minimize stagnation and recirculation zones. Finally, uniformity of mass flow rate and spray pattern was evaluated by cold flow tests and the mixing head design process was successfully verified the results.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.161-168
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• 2001

A Thermal Barrier Coating (TBC) can play an important role in protecting parts from harmful environments at high temperatures such as oxidation, corrosion, and wear in order to improve the efficiency of aircraft engines by lowering the surface temperature of the turbine blade. The TBC can increase the life span of the product and improve the operating properties. Therefore, in this study the mechanical and thermal properties of the TBC such as oxidation, fatigue and shock at high temperatures were evaluated. A samples of a bond coat (CoNiCrAlY) produced by the High Velocity Oxygen Fuel (HVOF) and Low Pressure Plasma Spray (LPPS) method were used. The thickness of the HVOF coating layer was approximately $450\mu\textrm{m}$ to 500$\mu\textrm{m}$ and the hardness number of the coating layer was between 350Hv and 400Hv. The thickness of the LPPS coating was about 350$\mu\textrm{m}$ to 400$\mu\textrm{m}$ and the hardness number of the coating was about 370Hv to 420Hv. The X-ray diffraction analysis showed that CoNiCrAlY coating layer of the HVOF and LPPS was composed of the $\beta$and ${\gamma}$phase. After the high temperature oxidation test, the oxide scale with about l0$\mu\textrm{m}$ to 20$\mu\textrm{m}$ thickness appeared at the coating surface on the Al-depleted zone was observed under the oxide scale layer.

• Corrosion Science and Technology
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• v.18 no.3
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• pp.78-85
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• 2019

The International Maritime Organization (IMO) will administer a new 0.5% global sulfur cap on fuel content from 1 January 2020, lowering from the present 3.5% limit. Seawater $SO_x$ (sulfur oxide) scrubbing is especially spray scrubbing and a promising alternative to complying with the IMO regulation. However, the ionization of $SO_2$ (sulfur dioxide) and the $H_2SO_4$ (sulfuric acid) formed from $SO_3$ (sulfur trioxide) is proposed to accelerate corrosion of the internal seawater pipe. Apparently, the corrosion of the scrubber seawater piping system occurs in a severe and frequent manner. Hence, in this study, electrochemical measurement and weight loss of carbon steel (used as seawater pipe in most of the ships) in diluted sulfuric acid solution were investigated to determine corrosion rate, corrosion current density, corrosion potential, electrochemical behavior, and impressed-current density. Accordingly, the corrosion rate of carbon steel sheet in various diluted sulfuric acid solutions was observed to be greater than that in natural seawater, thus suggesting the fundamental data to deal with corrosion problems in scrubber seawater pipe.

• Journal of ILASS-Korea
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• v.24 no.1
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• pp.21-26
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• 2019

In Korea, Medium-duty trucks are classified into GVW (Gross Vehicle Weight) 3.5~10tons. MDTs are mostly used for logistics or delivery between regions. There have been studied on diesel fuel vehicles for SUVs(Sports Utility Vehicle) or light-duty trucks. But MDTs have been not studied. Therefore, this study have been used MDTs for characteristic exhaust emission. Test was carried out using the certification test mode (NEDC, New European Driving cycle) and the NIER mode in chassis dynamometer of the MDTs. And emission gas was analyzed for PN (Particulate Number), PN size distribution and aldehydes, VOCs (Volatile Organic Compounds), PAHs (Polycyclic Aromatic Hydrocarbons). This paper concluded that EURO-IV trucks produced more MSATs than EURO V trucks. Depending on the engine temperature, more MSATs were generated in cold temperature than in the hot start operation. However, the driving speed, the opposite results was obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.11
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• pp.102-108
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• 2020

The demand for lightweight materials and high-strength steel has rapidly increased to help reduce the weight of a vehicle body; it improves the fuel efficiency of automobiles and provides passenger safety. Additionally, as the material becomes thinner, the demand for its resistance against corrosion becomes higher. Hence, the application of the surface-treated steel sheet has surged rapidly. In this study, a weld bonding experiment using a delta spot welding machine is performed on a thin sheet of a different material (Al6061-T6/GA440). The thickness of the material was kept at 1 mm to reduce the weight of the automobile body parts. Additionally, the purpose of this study is to control the heat input by applying the welding conditions of a multi-stage pressure pattern to improve corrosion resistance shear strength. The analysis of nugget diameter measurement, shear tensile test, and salt spray test was performed to achieve the aim.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.5
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• pp.262-269
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• 2022

In order to process materials such as engineering plastics, which are difficult to mold due to their high strength compared to conventional polymer materials, it is necessary to improve the hardness and strength of parts such as screws and barrels of injection equipment in extrusion system. High-velocity oxygen fuel (HVOF) process is well known for its contribution on enhancement of surface properties. Thus in this study, using the HVOF process, WC coating layers of different thicknesses were bonded to the surface of S30C substrate by controlling the movement speed of the spray nozzle and each property was evaluated to decide the optimization condition. Through the results, the thickness of WC coating layer increased from 0 to 200 ㎛ maximum, along with the decrement of nozzle movement speed and the surface hardness get increased. Especially, the coated layer with the thickness over 180 ㎛ under the nozzle speed 500 mm/s had high hardness than thinner layer. In addition, the amount of wear consumed per unit time was also significantly reduced due to the formation of the coating layer.

• Journal of ILASS-Korea
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• v.27 no.3
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• pp.155-160
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• 2022

Recently, major developed countries have strengthened automobile fuel efficiency regulations and carbon dioxide emission allowance standards to curb climate change caused by global warming worldwide. Accordingly, research and manufacturing on electric vehicles that do not emit pollutants during actual driving on the road are being conducted. Several automobile companies are producing and testing electric vehicles to commercialize them, but it takes a lot of manpower and time to test and evaluate mass-produced electric vehicles with driving mileage of more than 300km on a per-charge. Therefore, in order to reduce this, a simulation model was developed in this study. This study used vehicle information and MCT speed profile of small electric vehicle as basic data. It was developed by applying Simulink, which models the system in a block diagram method using MATLAB software. Based on the vehicle dynamics, the simulation model consisted of major components of electric vehicles such as motor, battery, wheel/tire, brake, and acceleration. Through the development model, the amount of change in battery SOC and the mileage during driving were calculated. For verification, battery SOC data and vehicle speed data were compared and analyzed using CAN communication during the chassis dynamometer test. In addition, the reliability of the simulation model was confirmed through an analysis of the correlation between the result data and the data acquired through CAN communication.

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.62-67
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• 2023

Recently, the global automobile industry is aiming for a transition from internal combustion locomotives to zero-emission vehicles. Electric vehicles powered by battery energy can operate at peak performance and improve fuel economy by applying multiple motors or multi-speed transmissions. In order to design a two-speed transmission, it is necessary to evaluate and analyze the application system and performance of electric vehicles. In this study, control performance optimization of a twostage battery electric vehicle equipped with an AMT-based automatic transmission was performed and performance according to control pattern changes was analyzed. In order to improve the operating efficiency of the motor, the shift control that sets the optimal operating point according to the vehicle speed and required torque was derived from the motor efficiency map. The performance of battery energy consumption and transmission loss energy according to the hysteresis interval was analyzed and optimized. The hysteresis interval applied to the optimal shift map acted as a factor in reducing the frequency and loss of shifts. It has been shown that keeping the hysteresis interval at about 4 km/h can reduce energy consumption while reducing the number of shifts.

• Journal of Institute of Convergence Technology
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• v.6 no.2
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• pp.35-40
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• 2016

Ignitor tip is a component of burner to start the burning process in power plant. This is used to ignite the coal to a constant operating state by fuel mixed with air and kerosene. This component is composed of three components so that air and kerosene are mixed in the proper ratio and injected uniformly. Because the parts with the designed shape are manufactured in the machining process, they have to be made of three parts. These parts are designed to have various functions in each part. The mixing part mixes the supplied air and kerosene through the six holes and sends it to the injecting part at the proper ratio. The inject part injects mixed fuel, which is led to have a constant rotational direction in the connecting part, to the burner. And the connecting plate that the mixed fuel could rotate and spray is assembled so that the flame can be injected uniformly. But this part causes problems that are worn by vibration and rotation because it is mechanically assembled between the mixing part and the inject part. In this study, 3D printing method is used to integrate a connecting plate and an inject part to solve this wear problem. The 3D printing method could make this integrated part because the process is carried out layer by layer using a metal powder material. The part manufactured by 3D printing process should perform the post process such as support removal and surface treatment. However, while performing the 3D printing process, the material properties of the metal powders are changed by the laser sintering process. This change in material properties makes the post process difficult. In consideration of these variables, we have studied the optimization of manufacturing process using 3D printing method.