• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.133-140
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• 2020

Traction performance of a tractor varies depending on soil conditions. Sinkage and slip of the driving wheel for tractor frequently occur in a reclaimed land. The objective of this study was to develop a tractor suitable for a reclaimed land. Traction performance was evaluated according to soil conditions of reclaimed land and paddy field. Field experiments were conducted at two test sites (Fields A: paddy field; and Field B: reclaimed land). The tractor load measurement system was composed of an axle rotation speed sensor, a torque meter, a six-component load cell, GPS, and a DAQ (Data Acquisition System). Soil properties including soil texture, water content, cone index, and electrical conductivity (EC) were measured. Referring to previous researches, the tractor traveling speed was set to B3 (7.05 km/h), which was frequently used in ridge plow tillage. Soil moisture contents were 33.2% and 48.6% in fields A and B, respectively. Cone index was 2.1 times higher in field A than in field B. When working in the reclaimed land, slip ratios were about 10.5% and 33.1% for fields A and B, respectively. The engine load was used almost 100% of all tractors under the two field conditions. Traction powers were 31.9 kW and 24.2 kW for fields A and B, respectively. Tractive efficiencies were 83.3% and 54.4% for fields A and B, respectively. As soil moisture increased by 16.4%, the tractive efficiency was lowered by about 28.9%. Traction performance of tractor was significantly different according to soil conditions of fields A and B. Therefore, it is necessary to improve the traction performance of tractor for smooth operations in all soil conditions including a reclaimed land by reflecting data of this study.

• 대한조선학회논문집
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• 제50권6호
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• pp.407-413
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• 2013

In the conventional towing tank, the ordinary towing carriage has a speed barrier which caused not only by the limitation of the length of towing tank but also the limitation of acceleration. Therefore the length of the towing tank should be decided carefully from the planning stage of the towing tank construction. Consequently the acceleration of the towing carriage should be taken less than 0.06g practically to avoid the slip of the wheel on rail. Due to the increasing demand of the high speed experiments on the development of special novel ship, the requirement of the high speed towing carriage is continuously increased recently. When the minimum measuring time of the towing experiment is prescribed as five seconds, the carriage should be accelerated with higher than 0.12 g to get the speed of 18 m/sec even in the towing tank having a length of 400m in length approximately. This means that the requirement of acceleration is bigger than twice of the ordinary practices of carriage acceleration. In such a condition the exerted total power of motor could not converted to traction force for the acceleration of the carriage without slip. To over come these difficulties a pair of horizontal traction wheels are reinforced to each of the ordinary vertical carrier wheel and appropriate suspension system has been devised for the towing tank of super high speed operation. It is believed that the design of novel suspension system adaptable for the high speed acceleration of towing carriage will play a important role as a reference for the remodeling of the towing tank for high speed experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.192-193
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• 2006

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion may also occur to AC electrical railroad system. These problems affect not only power system stability. but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, and then, it is analyzed voltage drop and power quality for AC electrical railroad system both with single-Phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.250-252
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• 2008

DC traction system generates leakage current because running rails are used in return circuit. And it is very important to estimate the leakage current to the train operation situation. Therefore this paper presents dynamic simulation technique that is very similar to the real operation situation using TPS and PSCAD/EMTDC. For this we model DC traction system included in DC substation, variable feeding circuit model and variable train model. And we extract train location and power using TPS program and use these data for dynamic simulation. Finally we can estimate leakage current to the various operation condition using dynamic simulation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
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• pp.73-76
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• 2000

Traction motors that is one of the rotating machines for urban transit EMU have been subjected to increased demand for higher operating temperature, more demanding duty cycles, higher starting current, frequent voltage transients and severe environmental exposure. With the advent of PWM drives using power IGBTs in addition to the thermal considerations, it is important to take into account the impact of the dielectric stress upon the winding insulation system life. In analyzing the life of the stator winding, which is the heart of the motor, the majority of all winding failures are usually caused by a combination of various stresses acting on the insulation materials and system. In this paper, to evaluate the expected life of traction motor for urban transit E.M.U. it is proposed a new test method of complex accelerating degradation.

• 전기학회논문지
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• 제60권2호
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• pp.285-292
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• 2011

DC traction power system is operated ungrounded so that minimize the stray current. Because the stray current is still present, a rail potential is increased. The ground faults in the DC railway systems are usually detected by a potential relay(64P). Moreover, if the rail potential goes high in the ordinary operating state because of the traction load, the potential relay would be maloperated. A presented protective relaying algorithm that can identify exactly the faulted region and can distinguish a ground fault from the potential rising of the rail is presented in this paper. This paper presents simulation technique that is very similar to the real operation situation using PSCAD/EMTDC.

• 조명전기설비학회논문지
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• 제12권4호
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• pp.20-28
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• 1998

This study proposes a new method to estimate voltage unbalance more exactly using Thevenin's equivalent circuit. The conventional simple formula were easily applied to evaluate voltage unbalance. Because the formula was derived on the assumption that traction load would be directly connected to the secondary windings of the main transformer, they could not consider the detailed characteristics of traction power supply system, for example, self and mutual impedances of rail, catenary and return feeder. So, the ac쳐racy of the results could not be guaranteed. The proposed algorithm is applied to a standard autotransformer-fed test system to analyze unbalance phenomena. Through simulations, we could evaluate voltage and current unbalance factors and compare the voltage unbalance of the three transformer connection schemes : single phase, V- and Scott-connections which are required for suitable train operation schedules. Additionally, we could determine the combinations of trains which can be operated under the unbalance factor limits.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.619-626
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• 2011

In this paper, while electric multiple unit is moving on the rail, the content of measuring and analysing electric power consumption is mentioned. In order to measure the electric power consumption, we developed the power record analysis equipment and installed it the inside of the converter and inverter system to record the electric power consumption measured by voltage sensor and current sensor. Moving on the rail, we analysed traction power used up and regenerative power by using the measuring instrument. We expect that the measured and analysed data will offer basic research material to devise a energy reduction plan and introduce a new EMU system with high efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1381-1383
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• 2000

A multi-train operation simulation software is under development, in this G7 Project for a High Speed Train System, to simulate the running performance, power consumption, signalling and operation. In the first stage, a Train Performance Simulation (TPS) software is introduced in this paper. This is a core module of whole system and gives some parameters of a train, e.g., its position, speed traction and braking power and electric power system state, etc. In this paper, calculation technique was used for voltage drop at the train's positions and major posts along the catenary line. The final program will be used as an evaluation tool for system performance in constructing a new line or introducing a new train system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.130-133
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• 1999

It is one of the most effective methods for improving the performance of electric railway vehicles to make better the wheel-railway adhesion characteristics. The purpose of this paper is to develop the equivalent reduction machine to experiment on the adhesion system. The experiment system makes it possible to change the wheel-rail adhesion force with various adhesion parameters, and therewith to test the adhesion control system with the reduction machine in a laboratory.