• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.440-445
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• 2011

This paper presents a new regenerative brake system of electric vehicles that employs a continuous variable transmission(CVT) and a flywheel. The developed device has advantages over existing regenerative brakes from a standpoint of reliability and versatility in actual driving conditions. The system consists of a CVT, two wheels, a flywheel, a coupling and auxiliary powertrain components. The CVT is designed as a combination of two cones and a roller, which causes the velocity difference between the wheel and the flywheel. The power flow of the flywheel system is controlled by the CVT roller and the coupling through step motors. A prototype has been developed and then its performance has been investigated for various operating conditions. Results show that the storage efficiency of the flywheel is much affected by the vehicle's velocity and it is reduced below 20% for high speed, as compared to the 25% efficiency for an ideal condition. The CVT is a primary factor for lowering the flywheel efficiencies due to large friction and slipping between the cone and the roller.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.5-10
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• 2005

The effect of ultrasonic energy for diesel fuel and blend oil has been revealed in this paper. The experimental setup consisted of a high speed diesel engine with 4 cylinder, dynamometer and ultrasonic fuel feeding system. Ultrasonic energy was added to diesel fuel and blend oil, which is a blend of diesel fuel and rape-seed oil. As engine speed was changed, engine torque and power, brake specific fuel consumption and thermal efficiency were measured in detail. As the results, by adding ultrasonic energy to diesel fuel and blend oil, the engine performance was improved in range of the experiment. The effect of improvement on brake specific fuel consumption and thermal efficiency for blend oil is higher than that for diesel fuel. When ultrasonic energy was added to diesel fuel or blend oil, a rise in engine torque for diesel fuel was higher than that for blend oil, but the effect of ultrasonic energy was small. From these results, it may be desirable to add ultrasonic energy to blend oil for the use of blend oil to diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.174-183
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• 2005

A train driving requires to n the fixed distance within given time, and it is desirable to consume low energy if necessary. Reducing energy consumption depends on the train operation modes by either manual or automatic operation. In this article, an operation to reduce energy consumption by changing modes of train operation by a driver without changing the train operation requirement is investigated. The powering model, braking model and consumed energy calculation model are developed, then simulated by using a Matlab software. The accuracy of the train dynamic model established by the simulations is verified by comparing with the real experimental data. Several simulations by various operations in the real track are executed, then the desirable pattern of train driving is found.

• Journal of the korean Society of Automotive Engineers
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• v.2 no.2
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• pp.1-15
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• 1980

에너지사정은 날이 갈수록 악화일로에 있으며, 이 추세는 장차 그 도를 심화시켜 갈 것으로 전 망된다. 이와 같은 상황하에서 거의 석유베이스의 연료에 의존하고 있는 내연기관 특히 자동차는 경제활동 및 국민생활에 불가결의 수단으로 제공되고 있는 바, 그 수요에 약간의 제동이 걸렸 다고 하지만, 장기적으로 볼 때, 수요증대와 이에 따른 공급증대는 필연적인 것으로 인정되고 있다. 내연기관의 연료로서 석유베이스가 아닌 신대체연료로서 가장 유망시되고 있는 것은 메타 놀과 수소로 보고 있다. 메타놀은 현재 알려진 제조법으로서는, 석탄이나 석유와 같이 매장량이 제한되어 있는 화석의 일차제품에 좌우된다는 문제를 내포하고 있는데 반하여, 수소는 물 및 핵에너지로부터 얻어지므로, 장기적으로 볼 때 가솔린의 일반적인 대용으로서 탄소를 함유하는 원재료에 의존하지 않는 대상이 되는 것은 수수뿐이다. 수소의 이용에 있어서, 제조소로부터 스탠드까지의 하부조직이 없는 것이, 자동차 내 저장문제와 더불어, 오늘날 수소자동차의 일반적 이용을 지지하고 있다고 하더라도, 수소동력은 그 배출가스가 거의 무해한 까닭으로, 가까운 장래에 시내교통과 같은 특수한 경우에는 활용할 수 있을 것이다. 또한 가솔린과 수소의 혼합 연료에 의한 운전을 서서히 도입함으로써, 수소기술로의 전환이 용이하게 된다. 이렇듯 탄소를 함유하는 원료에 의존하지 않는 대체연료로서 수소가 유망시되고 있는데, 이 때 신연료의 이용 가능성만이 중요한 것이 아니고, 연료의 제조, 저장과 분배, 수송, 그리고 자동차의 운전에 이 르기까지의 문제를 기술적 및 경제적 관점에서 파악하여야 한다. 그 가운데서, 특히 신연료가 자동차기관을 중심으로 한 내연기관의 대체연료로서 적합하냐 아니냐, 또한 기관, 연료계통 등에 별로 개조를 가할 필요가 있느냐 없느냐 하는 기술적 파악이 먼저 제기된다. 앞으로 이 문제에 한하여 논의하기로 한다.

• Journal of Hydrogen and New Energy
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• v.34 no.1
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• pp.69-76
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• 2023

An experimental study was conducted on a 4-stroke direct injection diesel engine to examine the combustion and emission characteristics of 1-octanol/diesel fuel blends. The concentration of 1-octanol in the fuel blends was 10%, 30%, and 50% by volume. Experiments were conducted by varying the engine torque from 6 Nm to 12 Nm at the same engine speed of 2,700 rpm. Results showed that the fuel conversion efficiency increased as the 1-octanol proportion increased under most experimental conditions. However, the brake specific fuel consumption increased due to the relatively low lower heating value of 1-octanol. The smoke opacity and the concentrations of NO_x and CO emissions generally decreased with brake mean effective pressure as the 1-octanol proportion increased. On the other hand, the unburned hydrocarbon concentration increased with an ascending ratio of 1-octanol.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.767-772
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• 2023

In this study, combustion experiments were conducted at various engine speeds under full-load conditions using a single-cylinder diesel engine by blending butanol, pentanol, and octanol with diesel at a volume ratio of 10%. Experimental results revealed that higher alcohol-diesel blends resulted in lower brake torque and brake power than pure diesel due to the lower calorific value and the cooling effect during evaporation. An evident improvement in the brake thermal efficiency of the blended fuels was observed at engine speeds below 2,000 rpm, with the butanol blend exhibiting the highest thermal efficiency overall. Furthermore, the brake-specific fuel consumption of the higher alcohol-diesel blends was lower than that of pure diesel at speeds below 2,200 rpm. When using blended fuels, the exhaust gas temperature decreased under lean mixture conditions due to heat loss to the air and the cooling effect from fuel evaporation.

• Tribology and Lubricants
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• v.18 no.4
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• pp.305-311
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• 2002

Three different kinds of brake discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. A braking test bench was specially designed to analyse thermo-mechanical and frictional behaviors of two types of brake with different sizes in stop and hold braking modes. Plasma spray coating technique was also used to coat the discs with ceramic powder. During the test four commercial brake pads were coupled with discs. Ceramic coated discs showed good stability in friction coefficient at high speed and high energy braking conditions. But they caused large wear loss of pad mass compared with the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. For a steel disc. it showed fluctuating friction coefficient at high speed but small wear loss of pad mass compared with ceramic coated discs.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.5
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• pp.197-202
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• 2003

When a high-speed train reduces its operating velocity while decelerating from a maximum of 350 to 50 [km/h], the train applies eddy-current brakes, which results in a deceleration time of approximately 3minutes. Therefore, a high current is utilized in order to obtain a large braking force. Consequently, the temperature of the electromagnet and rail increases significantly. In this paper, The thermal characteristics on a single magnet pole with convection heat transfer coefficient are simulated by using 2D-FEM. To verify the analysis results, the computed temperatures are compared with the experimentally measured temperature at stationary state. Furthermore, transient-state thermal analysis is performed to predict the magnet temperatures as the train is decelerating.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.62-67
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• 2001

The textiles supply rolling equipment is a part of inspection machine which inspect finished textiles and it check up textiles through rolling hydraulic equipment. This study suggests a method to select the capacity and initial gas pressure of accumulator to control reducing speed of the hydraulic motor to a desired degree. An accumulator in hydraulic systems is hydraulic machinery which stores kinetic energy of inertia body during braking. A series of computer simulations were done for the brake action and the selection method was based upon a trial and error approach. The results of the simulation work were compared with those of experiments and these results show that the proposed method can be applied effectively to control reducing speed of the hydraulic motor when braking action in textiles rolling system.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.97-107
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• 1998

Three different kinds of brake discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. Braking test bench was specially designed to analyse thermo-mechanical and frictional behaviors of two sizes of brake discs in stop and hold braking modes. And Plasma spray coating technique was used to coat ceramic powder on the discs. In the test four commercial brake pads were coupled with discs. Ceramic coated discs had shown good stability in friction coefficient at high speed and high energy braking conditions. But they caused large pad mass wear loss compared with the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. For a steel disc, it had shown fluctuating friction coefficient at high speed but a fittie pad mass wear loss compared with ceramic coated discs.