• Journal of the Korean institute of surface engineering
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• v.23 no.2
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• pp.30-38
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• 1990

For the purpose of suggesting the thermal resistant catalyst for automobile emission control, various catalysts, Pd-WO3 and PD-La2O3 systems, were charactrized before and after thermal aging. It was found that La2O3 formed amorphous surface compound on the support by strong metal-support interaction(SMSI). And by Temperature Programmed Desorption (TPD) expeiment, it was found that the distribution of acid site which is strong acid sites by adding the promoters. After thermal aging, it was observed that the acidity of Pd-WO3 system was decreased largely because of losing acid site by metal vaporization. On the other hand, there was pretty small change in the properties of matter of Pd-La2O3 system. Therefore, it could be considered that La2O3 formed heat resisting amorphous surface compound on the support by SMSI.

• Korean Journal of Materials Research
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• v.30 no.5
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• pp.246-251
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• 2020

The annealing characteristics of cold-rolled Al-6.5Mg-1.5Zn-0.5Fe-0.5Mn alloy, newly designed as an automobile material, are investigated in detail, and compared with those of other aluminum alloys. Using multi-pass rolling at room temperature, the ingot aluminum alloy is cut to a thickness of 4 mm, width of 30 mm, and length of 100 mm to reduce the thickness to 1 mm (r = 75 %). Annealing after rolling is performed at various temperatures ranging from 200 to 500 ℃ for 1 hour. The specimens annealed at temperatures up to 300 ℃ show a deformation structure; however, from 350 ℃ they have a recrystallization structure consisting of almost equiaxed grains. The hardness distribution in the thickness direction of the annealed specimens is homogeneous at all annealing temperatures, and their average hardness decreases with increasing annealing temperature. The tensile strength of the as-rolled specimen shows a high value of 496 MPa; however, this value decreases with increasing annealing temperature and becomes 338 MPa after annealing at 400 ℃. These mechanical properties of the specimens are compared with those of other aluminum alloys, including commercial 5xxx system alloys.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1825-1830
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• 2014

Environmental emission of recent automobile is drastically enhanced that it is one of the obvious assignments of exhaust system. This study is a purpose to establish of influence distribution on maxima and minima through the location of pressure on exhaust variable valve. The experiment are checked with real angles using camera which exhaust variable valve is opened side of point. Data has extracted to opening angles with internal flow, pressure. Exhaust variable valve through the floating analysis was analyzed the characteristic of location point about pressure and velocity. The pressures indicated the reduced results internal pressure within muffler. The velocity indicated an opposite results and vibration state of valve was verified to be operated as high speed from lower section. The conclusion to obtain from this study was found out the result to make the optimum back pressure condition as more increasing pressure distribution on valve face if the velocity location attracted by bottom point in order to improve for engine performance.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.96-104
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• 2017

A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection $c_1$, the cost of loss per unit time between failure and detection $c_2$, the cost of minimum repair of the detected breakdown of units $c_3$, and the overhaul cost $c_4$ of $R_s{\leq}R_g$. And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.2945-2950
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• 2011

As the step to improve fuel efficiency, there is the system to build up the eddy of combustion chamber at the suction line in order to increase the combustion efficiency. The models installed with no vortex generation system or with various shapes of the system are examined by fluid analysis. Vortex generation system is installed prior to the suction of combustion chamber. The wing of this system winds itself around the suction air and generates the vortex. This study investigates the flow of suction air and the pressure distribution of suction stroke by using the eddy generation system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1040-1044
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• 2013

The present paper has been accomplished to elucidate the characteristics of temperature change in a car washer heater system for removal of frost formed at the surface of a car. The previous studies had used a simplified mathematical modeling to analyse the temperature change characteristics for a car washer heater system. In the present study, an unsteady computational fluid flow and heat transfer analysis for a washer heater system has been done by using computational fluid dynamic analysis method. From the present CFD analysis, the time dependent temperature change in a car washer heater system has been analysed and derived the heating time and ejection temperature of the washer liquid to establish the optimal design basis for a washer heater system.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.115-120
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• 2015

Deep drawing of cylindrical cups is one of the most fundamental and important processes in sheet metal forming. Circular cups are widely used in industrial fields such as automobile and electronic appliances. Some of these cups are formed by a one-stage process, others such as battery cases and beverage cans are made by a multi-stage process. In the current study the multi-stage deep drawing of aluminum sheet metal is examined. The process consists of two deep drawing operations followed by two ironing operations. The press die, which can be used for the four-stage forming process, was manufactured allowing punch and die components to be easily changed for various experiments. The rolling direction of both the sheet and the drawn cups was always positioned toward the horizontal x-direction on the die face to minimize experimental errors during the progressive forming. The dimensional accuracy of the cylindrical cups formed at each stage and the earing defect due to the anisotropy of sheet were investigated. The influence of anisotropy on the thickness distribution was also examined. Both the thickness and the outer diameter of the cups were measured and compared for each set of experimental conditions. It was found that the dimensional accuracy of cups rapidly improves by employing the ironing process and also by increasing the amount of ironing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.730-737
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• 2016

Electric utilities may face new threats with increase in electric vehicles (EVs) in the personal automobile market. The peak demand will increase which may stress the distribution network equipment. The focus of this paper is on an adaptive control of smart household appliances by using an intelligent load management system (ILMS). The main objectives are to accomplish consumer needs and prevent overloading of power grid. The stress from the network is released by limiting the peak demand of a house when it exceeds a certain point. In the proposed strategy, for each smart appliance, the customers will set its order/rank according to their own preferences and then system will control the household loads intelligently for consumer reliability. The load order can be changed at any time by the customer. The difference between the set and actual value for each load's specific parameter will help the utility to estimate the acceptance of this intelligent load management system by the customers.

• Journal of the Economic Geographical Society of Korea
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• v.25 no.2
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• pp.203-218
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• 2022

The global value chain, as a major feature of the contemporary global economic system, has been mainly led by developed countries. Whereas developing countries have taken the relatively low value-added activities and this made geographical imbalances in value distribution. This imbalance in value distribution, however, began to gradually alleviated. Related to this phenomenon, the purpose of this research is to analyze the factors affecting factors. Focused on the method of upgrading the industry in the global value chain, the impact on the acquisition of value-added in developing countries was analyzed among the various factors to achieve the research purpose. Panel analysis was conducted on all industries, food and tobacco industries, textile and clothing industries, computer and electornics industries, and automobile industries of the OECD Value-Added Trade Data (TiVA). As a result of the analysis, it was confirmed that in all industries, value-added acquisition in developing countries was improved by increased total production, high value-added product production and participation in early stage. The analysis results by detailed industry showed slightly different patterns depending on the characteristics of each industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.1-8
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• 2017

This paper presents the development of an adaptive cruise control (ACC) system, which is one of the typical advanced driver assist systems, for 4-wheel drive hybrid in-wheel electric vehicles. The front wheels of the vehicle are driven by a combustion engine, while its rear wheels are driven by in-wheel motors. This paper proposes an adaptive cruise control system which takes advantage of the unique driveline configuration presented herein, while the proposed power distribution algorithm guarantees its tracking performance and fuel efficiency at the same time. With the proposed algorithm, the vehicle is driven only by the engine in normal situations, while the in-wheel motors are used to distribute the power to the rear wheels if the tracking performance decreases. This paper also presents the modeling of the in-wheel motors, hybrid in-wheel driveline, and integrated ACC control system based on a commercial high-precision vehicle dynamics model. The simulation results obtained with the model are presented to confirm the performance of the proposed algorithm.