• Journal of Powder Materials
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• v.13 no.4 s.57
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• pp.250-255
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• 2006

Wear behaviors of gas atomized and extruded Al-Si alloys were investigated using the dry sliding wear apparatus. The wear tests were conducted on Al-Si alloy discs against cast iron pins and vice versa at constant load of 10N with different sliding speed of 0.1, 0.3, 0.5m/s. In the case of Al-Si alloy discs slid against the cast iron pins, the wear rate slightly increased with increasing the sliding speed due to the abrasive wear occurred between Al-Si alloy discs and cast iron pins. Conversely, in the case of cast iron discs against Al-Si alloy pins, the wear rate decreased with increasing the sliding speed up to 0.3m/s. However, the wear rate increased with increasing the sliding speed from 0.3m/s to 0.5m/s. It could be due to adhesive wear behavior and abrasive wear behavior_between cast iron discs and Al-Si alloy pins.

• Journal of Welding and Joining
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• v.4 no.3
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• pp.32-42
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• 1986

In this study, the influence of carbon equivalents on friction welds of dissimilar steels was investigated. Four types of carbon steels with 10mm diameter were welded to a high-speed tool steel SKH 9. Main experimental results could be summarized as follows (1) Under constant friction pressure, the friction time increased almost linearly with the increasing burn-off length, while the forge length decreased almost linearly. (2) The maximum hardness in carbon steels increased almost linearly with the increasing carbon equivalent, but was much lower than that in the high speed steel. (3) After quenching and tempering of dissimilar steel friction welds, the hardness in carbon steel weldments became similar as that in the base metal, while the hardness in SKH 9 weld was still higher that of the base metal. (4) Relative movement in the friction phae occurred not at the interface of the weldments, but in the high speed steed steel near the interface. (5) For considered material combinations and welding parameters, most of fractures in tension and twisting tests occurred in the base metal. And welds with so high strength could produced in a wide range of welding parameters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.11 no.1
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• pp.21-25
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• 1975

Authors studied the propulsion efficiency of G. T. 280 to 300 class tuna longliners used in Korea. At first authors calculated the ratios and factors of the ship by use of principal dimensions. In cordance with this ratios and factors authors, examined the effective horse power, propulsion ficiency and brake horse power, and following results are obtained. (1) EHP is slightly increased according to the increasing of Froude number and speed. (2) Value of propulsion coefficient is obtained in the range of 51-54% at the cruising speed an its average is 52% in 6-13 knot of the speed. (3) EHP and BHP are increased according to the increasing of prismatic coefficient at the same speed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1360-1365
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• 2010

The TBO of main unit of propulsion control devices on high-speed railway vehicles proposed by the makers is appropriated 10 years cycle, but the maintenance of internal device are proceeding before coming to the particular period of time. In the Future, increasing of the failure probability occurred by increasing train service and obtaining spare parts are predicted that it would be difficult. the propulsion control devices develop is needed in other to the ease maintenance, cost savings and ensuring related domestic technologies when considering operating on long term of high-speed railway vehicles. In this paper, we proposed development a way that current-controlled type propulsion control devices using the newest power semiconductors which is easy to supply and demand through identifying performance and characteristics of existing current-controlled type propulsion control devices of high-speed railway vehicles.

• Laser Solutions
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• v.2 no.2
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• pp.42-51
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• 1999

This study has been performed to investigate into some effects of the output power and traverse speed of laser beam on the microstructures, hardness and fatigue resistance of the ductile iron surface-hardened by $CO_2$ laser defocussed beam. Optical micrographs have shown that with increasing the output power and decreasing the traverse speed, the martensite was coarsened and some retained austenite were appeared in ductile iron. The microstructures of hardening zone were composed of bull's eye and some nodular graphite dissolved structures by the effect of self quenching. Fatigue fracture characteristics of ductile iron have appeared in the high stress and low stress ranges. The fracture initiated at nodular graphites in the surface hardened layer due to the stress concentration caused by a notch effect. The interior graphite nodules were broken away or popped out during crack propagation. Fatigue test has shown that values of fatigue strength considerably increased with increasing output power at a given traverse speed.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.6-8
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• 2005

The plunger speed of solenoid actuator is affected by mass of plunger, magnetic motive force, inductance, and return spring. These factors are not independent but related with each other according to design characteristics of solenoid actuator. So, it is impossible to change the designed value for the purpose of increasing plunger speed. In this study, we have analyzed the characteristics of high-speed solenoid actuator having a non-magnetic ring which plays a role to concentrate the effective magnetic flux into plunger. For more detailed analysis, we have performed FEM analysis and decided the optimal attaching position and length on the guide tube based on these results. And, we proved the propriety of the non-magnetic ring effect by experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.554-554
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• 2000

To improve mechanical properties of Cu-Al-Ni alloy by the grain refinement, Cu-Al-Ni SMA ribbons were fabricated by melt spinning apparatus. The variations of microstructure, mechanical properties and transformation characteristics with the condition of rapid solidification and annealing time-temperature were investigated in Cu-Al-Ni SMA ribbons. The ribbons fabricated by melt spinning obtained around 1.5nm in width and 50-60${\mu}{\textrm}{m}$ in thickness. With increasing wheel speed in order of 10m/s, 15m/s, 20m/s, 30m/s and 3m/s, the grain size was decreased in order of 10${\mu}{\textrm}{m}$, 6.25${\mu}{\textrm}{m}$, 5.5${\mu}{\textrm}{m}$, 3${\mu}{\textrm}{m}$ and 3${\mu}{\textrm}{m}$. $M_{s}$ and $A_{s}$ temperature were decreased with decreasing grain size. By X-ray diffraction test, ordered $\beta$$_1$ phase was observed in all the SMA ribbons and the volume friction of it was increased with increasing wheel speed. With increasing wheel speed, strain was increased from 4.2% to 5.8% and fracture mode has changed from mixture of intergranular and dimple fracture to mixture of fiber structure and dimple fracture. The grain size of ribbon heat-treated at $600^{\circ}C$ was increased with increasing time. In the heat-treated ribbons at 55$0^{\circ}C$, ${\gamma}$$_2$ phases were observed.d.d.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.81-84
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• 2007

THE THERE HAS BEEN AN INCREASING DEMAND FOR THE NOISE IMPACT ASSESMENT BY HIGH-SPEED TRAINS DUE TO THE EXPANSION OF HIGH-SPEED RAILWAY. THIS PAPER PROVIDES STRATEGIES FOR THE EVALUATION AND THE ASSESSMENT OF THE POTENTIAL NOISE IMPACT RESULTING FROM PROPOSED HIGH-SPEED RAILWAY. FIRSTLY THE NOISE TECHNICAL SPECIFICATIONS FOR THE RAILWAY NOISE HAVE BEEN REVIEWED, AND THE STRATEGIES OF THE NOISE IMPACT ASSESMENT FOR HIGH-SPEED RAILWAY NOISE ABATEMENT HAVE BEEN DESCRIBED.

• Design & Manufacturing
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• v.16 no.4
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• pp.40-45
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• 2022

The EV electric vehicle market is growing rapidly worldwide. An electric vehicle means a vehicle that uses energy charged through an electricity source as power. The precision of the press is important to mass-produce the drive motor, which is a key component of the electric vehicle. The size of the driving motor is increasing, and The size of the mold is also growing. In this study, the precision of large high-speed presses for mass production of driving motors was measured. A study was conducted on the measurement method of press and the analysis of measurement data. A drive motor is a component that transmits power by converting electrical energy into kinetic energy. EV driven motors have key material properties to improve efficiency. The material properties are the thickness of the material. As a method for improving performance, use a 0.2mm thin steel sheet. Mold is also becoming larger. As the mold grows, the size of the high-speed press for mass production of the driving motor is also increasing. Also, the precision of the press is the most important because it uses a thin iron plate material. So the importance of large press precision is being emphasized. In this study, the effect of large high-speed press structure on precision was verified

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.429-433
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• 2000

Recently the demand of motor for industrial household machinery is increasing. As Switching devices and control technology are progressing so the use of BLDC Motor is increasing But 3-Phase BLDC Motor generally used has pulsating torque and speed variation in commutation so the range of it's application is limited high speed application Especially to solve these problems it is necessary to increase phase to Motor so study of Poly-Phase BLDC Motor is progressing. In this paper we designed 7-Phase BLDC Motor drive system and MSTC(Minimum Switching Time Controller)