• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.209-214
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• 2006

The eccentricity of the rotor causes a rotary machine to unbalance and the balancing to correct or compensate this is very important not only for dust-proof and anti -noise design but also for stabilization and durability of the rotary machine. In this paper, for developing the balancing machine to find and compensate such eccentricity, we will propose new way of measuring eccentricity using hall effect sensor that is different from the way in a conventional balancing machine. And we will show that it is possible to make balancing machine more compactly and cheaply by experiment results using hall effect sensor to measure eccentricity. Moreover we try to control and monitor the balancing machine by personal computer through serial communication.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.4
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• pp.19-25
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• 2007

A LNG safety valve functions to control a constant pressure inside the LNG line of transportation, and the flow through it accompanies with noise and vibration which affect adversely on the system. The present study aims at understanding the flow physics of LNG safety valve for a practical design of LNG safety valve. A computational work using the two-dimensional, axisymmetric, compressible, Navier-Stokes equations is carried out to simulate the gas flow through the LNG safety valve, and compared with the theoretical results. It is found that the shape of valve sheet and the gap size are the key parameters in determining the gas dynamic forces on the valve sheet, and there exists a distance between nozzle exit and valve sheet in which the thrust coefficient at the valve sheet increases abruptly.

• Journal of KSNVE
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• v.7 no.5
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• pp.837-845
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• 1997

The dynamic interactions between the reactor vessel and the control element drive mechanisms (CEDMs) of a pressurized water reactor are studied with the simplified mathematical model. The CEDMs are modeled as multiple substructures having different masses and the reactor vessel as a single degree of freedom system. The explicit equation for the frequency responses of the multiple substructure system are presented for the case of harmonic base excitations. The optimum dynamic characteristics of the CEDMs are presented to reduce the dynamic responses of the reactor vessel. The mathematical model and its response equations are verified by finite element analysis for the detailed model of the reactor vessel and the CEDMs for the harmonic base excitations. It is finally shown that the optimal dynamic characteristics of the CEDM presented can be applicable for the aseismic design.

• 대한공업교육학회지
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• v.31 no.1
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• pp.211-225
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• 2006

Gabion can be used for the purpose of preventing overflow of river and side loss of road. However the manufacturing process of the gabion is manually controlled especially to the joining process at the terminal part of gabion with small diameter wire. In this paper automatic feeding guide system was designed and fabricated to make automation. The fabricated system was tested in the factory level. Pneumatic system was considered as the main idea of the feeding system. 3/2-way and 5/2-way manual control valve, eight double-acting cylinders were used. The system took 46.48 seconds during a cycle. Additional environmental noise and vibration were not detected when the machine operated at the working area. Based on the theoretical simulation and actual test the fabricated system was well controlled. The system was applied to the patent in 2006.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.133-138
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• 2010

This paper describes on aerodynamic characteristics of pantograph system for Next generation high speed train(HEMU-400). The pantograph which supports electric power is located on the roof. Because of this, it generate high drag, severe acoustic noise and vibration which induced unstable flow due to complex configuration. Therefore, the design of high efficient pantograph needs to increase operational speed. In this research, wind tunnel tests were performed to design a high efficient pantograph system using 1/4 scaled model which were KTX-II pantograph, single arm pantograph and periscope type pantograph with square cylinder shape panhead and optimized shape panhead. For real operational condition, flow directions were adapted by rotation of pantograph. From this results of wind tunnel, it is checked that the pantograph with optimized panhead and single arm type or periscope type has better aerodynamic performance. In addition, lift control device and spoiler in pantograph were tested to investigate the validity of application.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.32-37
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• 2007

This paper proposes a dual-mode ultra precision positioning system for machine tools and measuring machines. The objective was to position a machine table with a picometer order of resolution, i.e., pico-positioning. A twist-roller friction drive (TFD) was used in coarse-mode positioning. The TFD, which was driven by an AC servomotor, is a kind of lead screw in mechanical terms, and several centimeters of machine table movement was controlled with a nanometer order of positioning resolution. To eliminate lateral vibration caused by the TFD, an active aerostatic coupling driven by piezoelectric actuators was inserted between the TFD and the machine table. This active aerostatic coupling was also applied as a feed drive device for fine-mode positioning; in the fine mode, the positioning resolution was 50 pm. Factors influencing pico-positioning, such as how noise from displacement sensors and vibrations in the aerostatic guideway affect positioning resolution, are discussed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.115-120
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• 2021

In this paper, an operating algorithm for single-phase permanent magnet synchronous motor based on PR current controller is proposed. In general, an asymmetric gap may occur depending on the shape of the rotor of single-phase PMSM, and this causes noise and vibration during high-speed operation. Therefore, in this paper, an operating algorithm for a single-phase PMSM usihng a proportional resonant current conrtoller with excellent control stability was proposed. Proportional resonant current controller has on steady state error is relatevly robust against distortion. Also, steady state error of AC input can be eleminated without complicated calculation process. The validity and availability of the proposed algorithm are verified through the experiment.

• Journal of Sasang Constitutional Medicine
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• v.7 no.2
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• pp.183-212
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• 1995

In order to investigate the influence of four Sasang prescriptions, $So{\breve{u}}min$ P'almunjat'ang(SPG), $So{\breve{u}}min$ Sltibimikwanjungt'ang(SSK), $T^{\prime}ae{\breve{u}}min$ $Chowis{\breve{u}}ngch^{\prime}{\breve{o}}ngt^{\prime}ang$(TCS), and $T^{\prime}ae{\breve{u}}min$ $Ch^{\prime}{\breve{o}}ngp^{\prime}yesagant^{\prime}ang$(TCP), on the activity of the autonomic nervous system in the rats exposed to noise and vibration stress, the contents of catecholamines in the urine, body temperature, heart rate, blood pressure, and stomach mucosa change were checked in this experiment. The results obtained were as follows; 1. On the 7th and 12th days from the beginning, the experimental indexes of the controled group were increased more than those of the normal group, and it meant that the noise and vibration stress induced an autonomic nervous system disorder in rats. 2. The urine-epinephrine contents in all experimental groups were decreased more than in the controled group, and in the Tcs and the Tcp groups those were significantly decreased on the 7th and 12th days. 3. The urine-norepinephrine contents in the SPK, TCS, and the TCP groups were significantly decreased on the 7th day, and in the TCS and the SPG groupsthose were significantly decredsed on the 12th day. 4. The urine-dopamine contents in the TCS group were significantlly decreased on the 12th day. 5. The body temperaature was decreased significantly in the SPG and the SSK groups on the 7th day. 6. The heart rate was significantly decreased in the SPG group on the 7th day, and it was decreased significantly in the SPG and the SSK groups on the 12th day. 7. The blood pressure was decreased in ghe SPG group significantly on the 7th day. 8. The stomach mucosa remarkably recovered from gastric ulcers in the SPG group and significantly recorvered in the other groups on the 7th day. From the above findings, th could be assumed that Taeumin and Soumin prescriptions had some significant influence on the control of the autonomic nervous system in the rats that recieved stress.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.608-616
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• 2006

Recently, a switched reluctance motor is widely used in various industries because it has many advantages such as a simple structure, robustness, less maintenance, high torque/weight ratio, and easy speed control over other types of motors. However, a switched reluctance motor inherently produces acoustic noise and vibration caused by torque ripple. Applications of these motors where silent operation is desirable have thus been limited. In this paper, a new stator pole face having a non-uniform air-gap and a pole shoe attached to the lateral face of the rotor pole are suggested in order to minimize torque ripple. The effects of each design parameter are validated using a time-stepping finite element method. The parameters are optimized by utilizing response surface method (RSM) combined with (1+1) evolution strategy. The result shows that the optimized shape gives higher average torque and drastically reduced torque ripple.

• Journal of the Korean Institute of Rural Architecture
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• v.23 no.3
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• pp.1-8
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• 2021

Rural multi-purpose buildings needs to ensure their safety against various disasters. Therefore, a pile foundation, which is a foundation type that can transmit the load of the structure to the bedrock layer, has been designed. The pile foundation method is largely divided into driving piles method and pre-bored pile method. Recently, in order to respond to the Noise and Vibration Control Act and related environmental complaints, construction of pile foundation adopts pre-bored pile method. The bearing capacity of the pre-bored pile method is calculated through a load test in situ. However, a disadvantage stems in that it is difficult to measure the ultimate bearing capacity due to field conditions. Therefore, in this study, the skin frictional force of pre-bored pile was measured through a model test in laboratory for each pile filling material. In result, the pile filling material with using circulating resources shows superior skin frictional force than ordinary portland cement. This study also judged that the result can be applied in place of ordinary Portland cement in the field.