• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.61-67
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• 2013

In this paper, it was studied how the critical speed which could occur hot judder due to disk temperature. Through the dynamometer experiment, we measured the critical velocity and surface temperature when the hot judder occur on the disk break. Also with the critical velocity theory equation and the temperature change graph of factors which used in the equation, we was induced experiment equation including theory equation and experiment values. And it has compared with the method which approach as linea. From this, we predicted the change of critical speed which could occur hot judder due to disk temperature. In addition, critical speed graph has compared with actual driving speed and disc temperature at a vehicle test. Therefore it was estimate to possibility of arising hot judder.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.72-84
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• 1988

Engine performance is one of the main objectives specified at the beginning of a new engine design project. The cycle simulation for SI engine is based on the zero-dimensional gas exchange model and a heat release expression by Viebe. This program also requires minimum input data and takes only a short time to run. Heat transfer from cylinder transfer formula. The flow coefficient (effective area) is calculated from valve lift using the standard flow coefficient curve and engine friction is calculated from the Millington and Hartles' engine friction formula. The chemical species considered in burned gas are 6 species CO, CO, H$_{2}$, H$_{2}$O, $O_{2}$, N$_{2}$ and the cylinder pressure, homogeneous cylinder temperature, gas composition and burned fraction are calculated at each crank angle through the cycle. To check the validity and accuracy, experimental study was done with 3 engines for measuring cylinder pressure, indicated mean effective pressure, brake mean effective pressure and air flow rate, etc. Despite its simple assumptions, cycle simulation showes excellent breathing and performance correlation when compared with data of tested engines, and have been proved useful in engine design.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.195-211
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• 2015

Flat plate friction lines have been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996), and the curve developed by Katsui et al. (2005). In the second part, change in the form factor by three kinds of friction resistance curves was investtigated based on model tests, and then the brake power and the revolution that were finally determined by expansion processes of full-scale ships. When three kinds of friction resistance curves were applied to each kind of ships, these were investigated: differences between resistance and self-propulsion components induced in the expansion processes of full-scale ships, correlation of effects between these components, and tendency of each kind of ships. Finally, what friction resistance curve was well consistent with results of test operation was examined per each kind of ships.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.1
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• pp.33-39
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• 2014

Automatic driving needs many functions such as the obstacle recognition, the lane recognition, and the lane change, etc. In this paper, we realized a system which automatically drove the three-kinds of vehicle driving course, to introduce and apply the concept of 'color recognition' that expands the scope of 'lane recognition' for vehicle driving. We made the reduced each course compared with RC(Radio Control) car size, and controlled the steering considering the position and the slope of the detection line and the speed. Because the RC car does not have the brake function, we consider the speed and the position of the detection line to stop the RC car.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.405-410
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• 2004

There are two types of noises in running the rail vehicle. The one is periodic by electric motors, dehumidifiers, and dusting machines. And the other is aperiodic squeal noise by the frictions between the wheels and the rail or the disks and pads. The periodic noises in rail vehicle have been reduced by changing DC motors to AC motors with silencers, and by improving the lubricants. However, almost nothing relating a periodic noise has been studied. In this paper, the experimental methods were applied to understand phenomena of the squeal noise, which was occurred by the friction variation due to aperiodic stick and slip with low repeatability in the process of dry friction of the disk and the pad when a rail vehicle was being braked. By the experimental acoustic test, it was found the specific frequencies relating the squeal noise. And by modal testing, it was measured the resonant frequencies in the disk and the pad-plate which were the components of the braking system, and in the whole braking system, and it was found the specific frequencies having the effects on the squeal noise.

• Journal of Korean Association for Spatial Structures
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• v.4 no.1 s.11
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• pp.77-86
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• 2004

It is the buckling of the compression portions of the deckplate that govern its behaviour under wet concrete construction loading. The size and position of intermediate stiffeners in the compression flanges of thin-plate steel decks exert a strong influence on the dominant buckling mode of the flange. Test sections composed of high-strength steel were brake pressed with a variety of Flat-hat intermediate stiffeners in the compression flange forming a progression from small to large stiffeners. The ABAQUS program to determine the effectiveness of intermediate stiffeners in controlling buckling modes is undertaken. A series of specimens are loaded with simple beam. Various buckling wave forms prior to ultimate failure through a plastic collapse mechanism. The experimentally determined buckling stresses are found to be comparable with studies performed using the ABAQUS program analysis and using each country code.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.61-65
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• 2014

Construction heat insulating material for construction is used in large amounts in industry. In the manufacturing process of this insulation material, a thermal insulation material is completed while a polymer in a liquid state passes through Hall breaker. At this time, the quality and form of a product are determined by a hole in the breaker according to the oil pressure of the fluid and the change of the flow velocity. The friction wear action with regard to partner movement between the two levels of quality of materials affects the performance and the lifetimes of machine parts. In this study of a friction test, SM45C, which is a material used to create brake holes, was used. PVC was used to create the specimen. Moreover, an experiment divided a lubricous state and an unlubricated condition. The resulting value over the load of a pin, the revolving speed of a disk, and the standby state of an experimental result disk could be acquired.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.112-118
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• 2003

The friction coefficients of the rubber for clutch master cylinder were experimentally measured in this study. The cylindrical rubber samples for primary cup-seal and secondary cup-seal were tested against the aluminum or the steel plates of master cylinder housing under the various conditions of brake oil temperatures and normal loads. Dry sliding friction coefficients were also measured under various load conditions. The test revealed following results. First, the friction coefficient under fluid lubrication condition in general decreases, as the oil temperature or normal load increases. Second, the steel plate of low surface roughness yielded comparatively low friction coefficient on the range of 0.30∼0.67. On the other hand, the aluminum plate of high surface roughness yielded high friction coefficient on the range of 0.31∼1.15. Third, the friction coefficient of dry surface contact decreases as the normal load increases. This is contrary to the general principle of friction coefficient between metal plates.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.72-80
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• 2013

This study is to develop and evaluate an AFS and an ARS controllers to enhance lateral stability of a vehicle. A sliding mode control (SMC) and a fuzzy logic control (FLC) methods are applied to calculate the desired additional steering angle of AFS equipped vehicle or desired rear steer angle of ARS equipped vehicle. To validate AFS and ARS systems, an eight degree of freedom, nonlinear vehicle model and an ABS controllers are also used. Several road conditions are used to test the performances. The results showed that the yaw rate of the AFS and the ARS vehicle followed the reference yaw rate very well within the adhesion limit. However, the AFS improves the lateral stability near the limit compared with the ARS. Because the SMC and the FLC show similar vehicle responses, performance discrimination is small. On split-${\mu}$ road, the AFS and the ARS vehicle had enhanced the lateral stability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1547-1551
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• 2011

The EFI small engine has been redesigned and manufactured based on a commercial small engine with a carburettor. Performance development of the EFI small engine has been conducted to optimize the operating conditions. Maximum torque and power were 12.56Ps and 25.4Nm, respectively, that were equivalent with carburettor type engine. Brake specific fuel consumption of the EFI small engine has been improved 17% on average compared with that of base small engine with a carburettor. By conducting KG2-6 mode test,HC+NOx was 7.46g/kWh that satisfied EPA Phase 3 regulation. THC has been reduced 41% on average, but NOx has been increased 3.5 times on average due to the improved thermal efficiency.