• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1870-1872
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• 2003

High voltage pulse generator with fast rise time has been studied theoretically and experimentally. The complexity and stray inductance of a pulse generator components can be very difficult to reduce. As a result, a compact size and stable Pulse can be obtained by using a rotary air-hole. Parametric studies showed that the rise time of the output pulse was depended little on the change of the revolutions per minute(RPM) while the pulse width of the output pulse was depended greatly upon the change of the revolutions per minute (RPM).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.2
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• pp.122-129
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• 1993

The heat transfer characteristics of the rotating heat pipe with a disc evaporator and a grooved condenser have been investigated by measuring temperature distributions of wall and vapor for various thermal inputs and revolutions per minute. The results showed that the heat transfer coefficients of all types are increased with thermal input and revolutions per minute. The heat transfer coefficient of evaporator with groove (pitch=2.5mm depth=1.5mm) is 25.8% higher than that of evaporator without groove at 500RPM, 150W.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.76-81
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• 2001

This paper place the focus the development of treadmill for rat in order to verify the effectiveness of exercise therapy. Up to now, in many medical laboratories treadmill have had to be remodeled for experiments with animal. Thus, it is necessary to develop the treadmills for animals only including rats. The treadmill has a DC motor which can make 600 revolutions per minute(600 RPM) and tension of the belt of the treadmill can be adjusted to prevent shift of the belt to any side. Velocity can be selected from 10m to 30m per minute increasing by 1m. The motor is controled by pulse width modulation(PWM) control mode using a 8bit microprocessor. In the future, the roller and motor need to be combined for improvement of stability and decrease of noise.

• Journal of Energy Engineering
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• v.14 no.3 s.43
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• pp.180-186
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• 2005

As an engine has a wide range of RPM $(3000\~12000\;RPM)$, variable control system is necessary in order to increase engine performance. SCV has been frequently referred to as a possible way to increase engine performance at low RPM. The purpose of this study is to investigate on the influence of SCV, specially at the range of lower revolution, in a high-speed small engine. Experiments were conducted on 4 Valves SOHC/air-cooling single cylinder engine and SCV shapes have been tested fur swirl intensity, the performance of power, fuel consumption and emission. As a result, we find to use SCV range be below 5000 RPM which fuel consumption decreased $9\%$.

• The Journal of the Acoustical Society of Korea
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• v.23 no.4
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• pp.309-315
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• 2004

To estimate the rate of noise contribution caused in each part of a vehicle in the course of a pass-by noise test. researches precedent have been made to study characteristics of nearby radiation noise measured on both sides of cars in a stationary state. With different revolutions per minute of engine. 2.800rpm and 3.200rpm respectively, in the measurement area of pass-by noise, the experiments have been conducted 7.5 meters away from the central axis of the test vehicle to study direction radiation according to frequencies. The results can be applied to reduce vehicle noise.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.141-147
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• 2016

A direct PM generator has the effect of reducing the mechanical noise and ease of maintenance by eliminating a number of power transmission components. In addition, wind turbines operating at low speed with the advantages of high output, high efficiency, and small size. The generator was designed as a small direct-drive PM generator that can be applied to a kite even at low wind speeds. The RPM (Revolutions Per Minute) of the reel was measured in two ways using a cadence/speedometer sensor and a tachometer while the actual kite. The RPM derived from the experiment was applied to the simulation on the designed generator. The no-load characteristic analysis for the magnetic fields produced for the permanent magnet generator by a permanent magnet and stator winding currents is achieved using a 2D coordinate system. A commercial electromagnetic analysis program, ANSYS Maxwell, was used to model the electromagnetic dynamics.

• Transactions of Materials Processing
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• v.24 no.4
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• pp.256-263
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• 2015

Electric resistance spot welding has been used to join overlapped steel sheets in automotive bodies. Recently to reduce weight in automotive vehicles, non-ferrous metals are being used or considered in car bodies for hoods, trunk lids, doors parts, etc. Various welding processes such as laser welding, self-piercing rivet, friction stir welding are being used. In the current study, a new electric resistance heated friction stir spot welding is suggested for the spot welding of non-ferrous metals. The welding method can be characterized by three uses of heat -- electric resistance heating, friction stir heating and conduction heating of steel electrodes -- for the fusion joining at the interfacial zone between the two sheets. The welding process has variables such as welding current, diameter of the steel electrodes, revolutions per minute (rpm) of the friction stir pin, and the insert depth of the stir pin. In order to obtain the optimal welding variables, which provide the best welding strength, many experiments were conducted. From the experiments, it was found that the welding strength could be reached to the required production value by using an electrode diameter of 10mm, a current of 7.6kA, a stirring speed of 400rpm, and an insert depth of 0.8mm for the electric resistance heated friction stir spot welding of 5052 aluminum 1.5mm sheets.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.334-339
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• 2010

The development of high-speed spindle have been studied extensively for micro machining in advanced industrial countries. The research of miniaturized high-speed air spindle is important part which needs for the micro machining process of high quality. So, This study was to carry out results about design characteristics of miniaturized high-speed air spindle. We had designed 4type turbines and shaft. They were simulated in use the computer simulation programs. We made them as products. They measured RPM (revolutions per minute). As a result of experiments, there was a contrast among 4type Turbines. it reached 384,000rpm in 4.5bar of air pressure. And, We tried to compare the results of measurement whit the results of computer simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.338-338
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• 2007

$LiFePO_4-C$ cathode materials were prepared by hydrothermal reaction and ball-milling. In order to enhance the electronic conductivity of $LiFePO_4$, 10% of acetylene black was added. During the ball-milling, different revolutions per minute (100, 200 and 300 rpm) was carried out. The structural and morphological performance of $LiFePO_4-C$ powders were characterized by X-ray diffraction and scanning electron microscope. The X-ray diffraction results demonstrated that $LiFePO_4-C$ powders had an orthorhombic olivine-type structure with a space group of Pnma. $LiFePO_4-C$ batteries were characterized electrochemically by charge/discharge experiments. The charge/discharge experiments indicated that $LiFePO_4-C$/Li batteries by 300 rpm of the ball-milling exhibited the best electrochemical performance with the discharge capacity of 126mAh/g at a discharge rate of $0.1mA/cm^2$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.346-353
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• 2022

Recently, studies on the integrity of rotating machines, such as gantry cranes, which are used in the shipbuilding industry, have been actively conducted. Gantry cranes are driven at relatively low revolutions per minute (RPM), are frequently operated and stopped, and are impacted by external environmental factors, such as shock and noise in the measurement data. The purpose of this study was to construct a replica of a gantry crane hoist used in indoor shipbuilding and analyze the acquired data for errors caused by the shift in operating conditions (RPM) and the change in the position of the data acquisition sensor. Consequently, we observed that the error caused by differences in sensor positions did not occur significantly under low operating conditions but occurred significantly under relatively high operating conditions. Thus, we determined that both the operating condition and position of the acquisition sensor affected the data acquired by the rotary machine.