• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.10
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• pp.681-686
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• 1999

In this study, a windmill type ultrasonic motor operated by single-phase AC electric field was fabricated, and then revolution characteristics and 3-dimensional vibration mode of the ultrasonic motor were investigated. Brass metal was pressed with umbrella-type using metal mold, then slot of 4 kind was processed at various thickness. It was found that the revolution speed of the ultrasonic motor increased with decreasing the thickness of elastic body. The revolution speed of the ultrasonic motor increased with increasing the slots of elastic body. When the characteristics was measured, applied voltage was changed from $10V_{max}\; to\; 100V_{max}$. Then, revolution was began from $30V_{max}$, if voltage was applied over $90V_{max}$ revolution speed was saturated, and not increased. The maximum revolution speed was 510[rpm] when using elastic body with 6 slots and thickness of 0.15mm. And 3-dimensional displacement mode was rotated clockwise direction.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.749-751
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• 1998

In this study, the wind-mill type ultrasonic motor was fabricated, and then revolution and temperature characteristics of the ultrasonic motor were measured. Brass metal was pressed with umbrella-type using metal mold, then slot of 4 kind was processed in each of thickness. Among sixteen's ultrasonic motors, heat loss on applied voltage was much at stator of the highest resonant point, but heat loss on applied voltage was almost neglected at the lowest resonant point of stator. The thickener thickness of elastic body, revolution speed was decreased. The more slot of elastic body, revolution speed was increased. Applied voltage was changed from $10V_{max}$ to $100V_{max}$. When applied voltage was under $20V_{max}$, ultrasonic motor was not rotated. When applied voltage was over $90V_{max}$, revolution of ultrasonic motor was saturated. Maximum revolution speed was 510[rpm].

• Journal of Korea Foundry Society
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• v.21 no.5
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• pp.296-303
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• 2001

The effects of the revolution speed on the mechanical properties and microstructure of Cr-Mo steel during vertical centrifugal casting using investment mold were investigated. The casting yield, tensile strength, hardness and absorbed energy during impact test were increased with increasing revolution speed. The effect of mass variation caused by the change in the revolution speed on the grain size was the most significant.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.24-34
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• 2021

This paper predicts the speed-power-rpm relationship in regular head waves using various indirect methods: load variation, direct powering, resistance and thrust identity, torque and revolution, thrust and revolution, and Taylor expansion methods. The subject ship is KVLCC2. The wave conditions are the regular head waves of λ/LPP = 0.6 and 1.0 with three wave steepness ratios at three ship speeds of 13.5, 14.5 and 15.5 knots (design speed). In the case of λ/LPP = 0.6 at design speed, two more wave steepness ratios have been taken into consideration. The indirect methods have been evaluated through comparing the speed-power-rpm relationships with those obtained from the resistance and self-propulsion tests in calm water and in waves. The load variation method has been applied to predict propulsive performances in waves, and to derive overload factors (ITTC, 2018). The overload factors have been applied to obtain propulsive efficiency and propeller revolution. The thrust and revolution method (ITTC, 2014) has been modified.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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• pp.29-33
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• 1986

This paper aims at finding out the optimum operating condition to reduce fuel consumption for the training ship Pusan 402 with controllable pitch propeller. For this purpose, this paper examints the variation of ship speed and fuel consumption in accordance with the change of engine revolution and propeller pitch. The results obtained are as follows: 1. When engine revolution is constant, the ship speed sluggishly increases according to the increase of propeller pitch but fuel consumption extremely increases. The higher revolution the engine is, the more remarkable this tendency is. 2. As the engine revolution becomes lower, the fuel consumption per mile decreases. Howt.er = the fuel consumption under the same engine revolution differs according to the propeller pitch. 3. Specific fuel consumption is uniformed about 180g/ps.h at any case of load. 4. Among the various operating conditions which yield the same ship speed, fuel consumption lowers in the case of lower engine revolution and larger propeller pitch.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.17-24
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• 2001

In order to investigate a characteristic of the behavior of spray pattern in accordance with running conditions for a DI diesel engine, the PLN Injection system with changeable revolution speed of fuel injection cam was set up, and through this, history curves of injection pressure for a similar real DI diesel engine were able to be displayed. Authors visualized and analyzed the sprays at various revolution speed of fuel injection cam, and found out that fuel distributions of the sprays in the low speed condition were bad, fuel with air was injected from the hole of nozzle at the beginning of injection, and wide spray angle at the early stage of injection became narrower with elapsed time, but wider again at the end of injection.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.556-562
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• 2011

Railroad started from invention of stream locomotive at the beginning of the industrial revolution. Development of diesel and electric locomotives in railroad induced science and technology since the industrial revolution. Korean high-speed train so-called high-speed train project, is localized 86.7%(compared to price), 92%(compared to number of parts). This technology has been contributed to KTX since 2004. High-speed railway was developed to integrated system, which is contained high technology such as civil, mechanical and electrical technology. This effects to advanced technology across the board science, technology, industry. High-speed railway is fast, safe, comfortable, eco-friendly as next generation's representative transportation. Furthermore it is inaugurate the era of the new railroad. Korea is opened the high-speed railway following Japan, France, Germany, Spain. Korea became the fifth nation of the high-speed railway. It joins the rank of developed countries operating at the speed of 300km/h. Especially, KTX is emerging as advanced transportation with reducing logistics costs significantly due to time advantage and transportation revolution. The purpose of this study is to present the strategy through internal and external railway market's analysis for Korea railway system's globalization expansion(overseas expansion).

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.81-87
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• 1998

High-speed machining is one of the most effective technologies to improve productivity. Because of the high speed and high feedrate, high-speed machining can give great advantages for the machining of dies and molds. In this paper, high-speed machining for HP-4 die material was carried out with a coated tungsten carbide ball endmill. In the high-speed machining, the cutting force and surface roughness of workpiece show various characteristics in different cutting conditions. Especially, the surface roughness of the workpiece depends largely on pick feed and feed-per-revolution of the ball endmill. In the condition where pick feed and feed-per-revolution are equal, better surface roughness is measured. By obtaining good surface roughness at high speed, efficiency of machining can be increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.36-40
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• 1996

The high-speed machining is one of the most effective technology to improve productivity. Because of the high speed and high feedrate, high-speed machining can give great advantages for the machining of dies and moulds. In this paper, high-speed milling for HP-4 die material was carried out with coated tungsten carbide ball endmill. In the high-speed machining, the cutting force and surface roughness of workpiece show very various characteristics at different cutting conditions. Especially surface roughness of workpiece depends largely on pick feed and feed per revolution of ball endmill. In the condition that pick feed and feed per revolution are equal, better surface roughness is measured. By obtaining good surface roughness at high speed, efficiency of machining can be increased.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.6
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• pp.94-103
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• 1997

This paper presents motor speed and revolution angle detection method using a sinusoidal AC tacho-generator. The 2-phase or 3-phase output tacho-generator can be adopted, and its' output voltages must have sinusoidal waveforms. Because the detection algorithm is simple, the proosed method can be implemented with analog devices or microprocessor conveniently. And the proposed method has a very short detection delay time. Especially in the analog implementation, there is no delay time without the settling time of analog devices. With the experimental results, it is verified that the proposed method can acculately detect the instantaneous motor speed and revolution angle over the wide ranges.