• 한국기계가공학회지
• /
• 제13권6호
• /
• pp.111-118
• /
• 2014

Aluminum lithium alloys are new materials developed for lightweight aircraft parts. However, as compared with conventional aluminum alloys in high-speed machining, problems such as tool wear, machining distortion, and cutting ability arise. This study presents the machining distortion characteristics of an Al-Li alloy wing tip in relation to the cutting heat in high-speed machining. A machining experiment was conducted with high-speed machining equipment for an evaluation of the machining distortion characteristics, with each machining stage temperature change of the workpiece machining surface, and the inside and outside temperature changes of the equipment measured. By measuring the amount of distortion of the workpiece before and after machining, the cutting heat was analyzed with regard to its effect on machining distortion in the product.

• International Journal of Railway
• /
• 제6권2호
• /
• pp.69-77
• /
• 2013

In this study, numerical analysis and model experiments were conducted to analyze behavioral characteristics acting on the track roadbed with excavation through steel pipe injection, a non-exclusive method of crossing construction under railroad as primary target. In model experiments that simulate injection excavation behaviors with an increase in the depth of soil cover, the upper displacement was measured by construction of the first and the second pipes in order to predict actual behaviors, and the behavior characteristics were verified through numerical analysis. The investigation results showed that surface displacement was smaller under the condition of higher soil cover. In the case of injecting two pipes, when the first pipe was injected, deformation of the surface increased linearly in both settlement and uplift experiments. However, when the second pipe was injected, the amount of change was found to be very small due to the relaxation and plastic zones around the first pipe. In addition, the results of numerical analysis on the same cross section with the model experiment found that the results of investigation into settlement ratio and volume loss were in very good agreement with those obtained by the model experiment.

• 한국기계가공학회지
• /
• 제10권5호
• /
• pp.13-19
• /
• 2011

In this paper, the active monitoring and control system is developed. This system can monitor the status of high the speed spindle in real time during its processing, and can analyze its influence of dimensional accuracy and processing if any, and can control the machining condition to realize the machining system equipped with active monitoring and self-diagnostic features. Machining experiment was performed on 3 materials Al, Brass and S45C in order to derive the relation between active monitoring and control algorithm by the machining load. In addition, we measured surface roughness of processing specimen along with the data change of spindle rotating speed and conveying speed according to variation of machining load. Based on these experiments, we derived relations for each material that can be applied to the control algorithm to allow self control of the rotating speed and conveying speed according to the machining load.

• Journal of Advanced Marine Engineering and Technology
• /
• 제20권3호
• /
• pp.121-130
• /
• 1996

Permanent magnet synchronous motor is widely used in industrial drive applications due to high efficiency, high power ratio, and easy maintenance. Position and speed detectors required in this motor increase the drive cost, and reduce the application range. Some papers present the speed control without position and speed detectors using DSP characterized by high processing performance. However, DSP increases the cost, and makes the inplementation difficult. This study has performed the speed control without position and speed detector by means of the microprocessor system which can be easily accessed. The results of simulation and experiment showed comparatively good dynamics in spite of the sensorless system.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.112-122
• /
• 2006

Is the high speed train with 300km/h running speed safe from derailment when it meets the mid or small-size earthquakes? In the present step, it is not so easy to judge whether it'll be derailed or not during an earthquake. However, we could elevate the running safety of high speed train as making it slow or even stop. The main objective of this study is to make the domestic running regulation and the re-running manual for high speed train with reference to the standards of France, Japan etc. To do so, numerical analysis and experiment will be performed from the next year. In addition, we'll evaluate possible places of derailment during an earthquake and make a database based on the Geographic Information System to effectively manage them.

• 한국정밀공학회지
• /
• 제21권1호
• /
• pp.133-139
• /
• 2004

High speed machining (HSM) can reduce machining time with the high metal removal rate by high speed spindle and feedrate. This paper supports HSM technology using the small size tool with the optimal tool path generation and modification of tool change. The optimum tool path is generated to reduce cutting length of cavity pattern and change the cutting tool for preventing the tool breakage by wear. The tool path is modified with the experiment data of tool wear and breakage to support tool change on reasonable time. The result can contribute to HSM technology of high hardness materials using the small size end-mill.

• 반도체디스플레이기술학회지
• /
• 제16권2호
• /
• pp.49-54
• /
• 2017

In this paper, recent researches on new and renewable energy have been conducted due to problems such as energy exhaustion and environmental pollution, and new researches on high efficiency and high speed switching are needed. Therefore, we compared the efficiency by using high speed switching devices instead of IGBT which can't be used in high speed switching. The experiment was performed theoretically by applying the same parameters of the high speed switching devices which are the Cool MOS of Infineon Co., SiC C3M of Cree, and GaN FET device of Transform, by implementing the DC-DC boost converter and measuring the actual efficiency for output power and frequency. As a result, the GaN FET showed good efficiency at all switching frequency and output power.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(I)
• /
• pp.199-203
• /
• 2003

Computer aided simulation is becoming an essential part in planning, design, and operation of railway systems. To determine the adequate performance and specification of railway system, it is necessary to calculate rotting stock's performance such as distance, speed, power etc when train's running. This paper presents result of train performance simulation using the program that developed in advance for Korea high speed train. To verify result of simulation, we have compared that with experiment data.

• 한국정밀공학회지
• /
• 제19권4호
• /
• pp.140-146
• /
• 2002

High speed rotating machines can be very sensitive to rotating mass unbalance that is a major source of harmful vibration for many types of rotating machinery. So, the balancing procedure is needed for all high-speed rotating system. To save the time and cost of off-line balancing, many researchers have developed the on-line balancing devices and methods. In this paper, an active balancing device, which is an electro-magnetic type, is developed and the active balancing algorithm using influence coefficient method is also proposed. The active balancing experiment for flexible rotors during operation is performed by an active balancing device. As a result, controlled unbalance responses are below the vibration limit at all rotating speed ranges with critical speed.

• 전기학회논문지
• /
• 제58권1호
• /
• pp.69-76
• /
• 2009

This paper describes sensorless high-speed control for 45,000rpm/22kw type PMSM by using iterative adaptive sliding mode observer. The proposed algorithm is based on sensorless vector control by on-line estimating the speed of rotor in the wide speed operating range between the starting operation. In addition, it shows the enhanced performance of the iterative adaptive observer by lessening its chattering and getting stable response in limited PWM period. The simulation and experiment results show the reliable performance of the proposed algorithm through starting to high speed operating range.