• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.603-609
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• 2015

Railway vehicles driven by wheels obtain force required for propulsion and braking by adhesive force between wheels and rails, this adhesive force is determined by multiplying adhesion coefficient of the friction surface by the applied axle load. Because the adhesion coefficient has a peak at certain slip velocity, it is important to determine the maximum values of the friction coefficient on the contact area. But this adhesive phenomenon is not clearly examined or analyzed. Thus we have developed new test procedure using the scaled adhesion test-bench for analyzing of the adhesion coefficient between wheel and rail. This adhesion test equipment is an experimental device that contacts mutually with twin disc which are equivalent to wheels and rails of railway vehicles.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.537-544
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• 2005

This paper presents the efficiency measurement and energy analysis for a parallel HEY. Using the HEV test rig, the efficiency of each powertrain component is measured for a given driving cycle including the regenerative braking system. Accompanied by the efficiency measurements, a detailed energy analysis is performed. Based on the efficiency measurement and energy analysis, a HEV performance simulator is developed. Using the simulator, the HEV performance is evaluated for a mild hybrid system. It is expected that the HEV simulator developed can be used to obtain further optimization potentials.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.930-937
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• 2013

In this paper, a motor control algorithm for performing a mode change without an integrated starter generator (ISG) is suggested for the automatic transmission-based hybrid electric vehicle (HEV). Dynamic models of the HEV powertrains such as engine, motor, and mode clutch are derived for the transient state during the mode change, and the HEV performance simulator is developed. Using the HEV performance bench tester, the characteristics of the mode clutch torque are measured and the motor torque required for the mode clutch synchronization is determined. Based on the dynamic models and the mode clutch torque, a motor torque control algorithm is presented for mode changes, and motor control without the ISG is investigated and compared with the existing ISG control.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.70-75
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• 2001

Intensive experimental investigations were carried out to provide information of the effects of inflow on the rolling characteristics and stability of ships, which becomes great concern in relation to ship's capsizing. A series of systematic experiments have been performed considering the effects cf combined motion of roll-heave-sway and relevant parameters, such as roll angle and period, tank water height etc. To accommodate this type of experiments with 3-degree of freedom of motion, a bench tester has been developed and verified using existing data. Also, theoretical application of anti-roll tank has been incorporated to support the process of investigation. A model of Ro-Ro ships is used in the present study as this type of vessels, as well as fishing vessels, with large open decks, can loose stability rapidly when there is inflow on the decks.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.883-890
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• 2005

In this study, 2 pure hydrocarbon refrigerants of R1270 (Propylene) and R290 (Propane) and 3 binary mixtures composed of R1270, R29O and R152a were tested in a refrigerating bench tester with a scroll compressor in an attempt to substitute R502 used in most of the low temperature applications. The test bench provided 3\sim3.5$ kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of -28 and $45^{\circ}C$ in the evaporator and condenser, respectively. Test results showed that all refrigerants tested had $9.6\sim18.7\%$ higher capacity and $17.1\sim27.3\%$ higher COP than R502. The compressor discharge temperature of R1270 was similar to that of R502 while those of all other refrigerants were $23.7\sim27.9\%$ lower than that of R502. For all alternative refrigerants, the amount of charge was reduced up to $60\%$ as compared to R502. Overall, these alternative refrigerants offer better system performance and reliability than R502 and can be used as long term substitutes for R502 due to their excellent environmental properties.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.5
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• pp.403-410
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• 2007

In this study, natural refrigerants and their mixtures that can supplement and replace R12 and R134a in automobile air-conditioners are studied. R134a is currently used as the refrigerant in new motor vehicle air conditioners, replacing the ozone depleting refrigerant R12. Although R134a has no ozone depletion potential, it has a relatively large global warming potential, approximately 1300 times that of $CO_2$ over a 100 year time horizon. For this reason, performance of natural refrigerants and their mixtures containing R152a, RE170 (Dimethylether, DME) and R600a (Isobutane) are measured under 2 different temperature conditions. They were tested in a refrigerating bench tester with an open type compressor. The test bench provided about 4 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. Test results show that the coefficient of performance (COP) of these refrigerants is up to 21.55% higher than that of R12 in all temperature conditions. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for automobile air-conditioners.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.10
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• pp.761-767
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• 2006

In this study, performance of 2 pure hydrocarbons R290 and R1270 was measured in an attempt to substitute R22 under 3 different temperature conditions. They were tested in a refrigerating bench tester with a hermetic rotary compressor. The test bench provided about 3.5 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of $7/45^{\circ}C$ and $-7/41^{\circ}C$ and $-21/28^{\circ}C$ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by $14{\sim}31^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.58-63
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• 2006

In this study, performance of 2 pure hydrocarbons and 3 mixtures was measured in an attempt to substitute R22 under 3 different temperature conditions. The mixtures were composed of R1270(propylene), R290(propane) and R152a. They were tested in a refrigerating bench tester with a hermetic rotary compressor The test bench provided about 3.5 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of $7^{\circ}C/45^{\circ}C$ and $-7^{\circ}C/41^{\circ}C$ and $-21^{\circ}C/28^{\circ}C$ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by $14{\sim}31^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.2
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• pp.21-30
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• 1990

Theoretical and experimental techniques to analyze the two-dimensional liquid motion in a tank are discussed. A Lagrangian FEM with a velocity correction procedure is introduced to describe incompressible free surface fluid flow. A mesh rezoning technique is used to prevent strong distortion of finite elements in the Lagrangian description. Model test technique for sloshing tank is developed using a hydraulic type bench tester. The influence of the variation in the exciting frequency and amplitude are observed for various fill depths. The results of theoretical calculations are compared with those of experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.391-400
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• 2012

In this study, performance of HFC32/HFC152a mixture is measured in the composition range of 20 to 50% R32 with an interval of 10% for the comparison with the conventional HCFC22 in water-source heat pumps. Tests are carried out under the same capacity in a heat pump bench tester equipped with a variable speed compressor at the evaporation and condensation temperatures of 7/$45^{\circ}C$ and -7/$41^{\circ}C$ for summer and winter conditions, respectively. Test results show that the compressor power of the HFC32/HFC152a mixture is 13.7% lower than that of HCFC22 while the coefficient of performance(COP) the HFC32/HFC152a mixture is 15.8% higher than that of HCFC22. Hence, from the view point of energy efficiency, the HFC32/HFC152a mixture is excellent as compared to HCFC22. Compressor discharge temperatures of HFC32/HFC152a mixture are increased up to $15.4^{\circ}C$ as compared to that of HCFC22. The amount of charge for HFC32/HFC152 mixture decrease up to 27% as compared to that of HCFC22. Overall, HFC32/ HFC152a mixture is an excellent long term candidate to replace HCFC22 in water-source heat pumps.