• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.633-640
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• 2007

In this paper, 3-D reciprocating compressor is taken into flow-structure interaction analysis. The full cycle process consisted of cylinder expansion and compression has been modeled without considering flow leakage through cylinder wall. Fully-coupled FSI analysis of this compressor model was iteratively solved and gives sufficient result with the experimental test. The study is emphasized to thoroughly investigate discharge valve motion, opening and closing, in order to determine discharge valve region which is prone to have high effective stress. The cylinder pressure is successfully validated before conducting impact analyses between discharge valve and other susceptible supported structure. Velocity profile has been obtained in FSI analysis is used as initial condition to carry out further impact analyses. Stress result of discharge valve and valve spring gives preliminary estimation of higher stress area due to its impact phenomena.

• Smart Structures and Systems
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• 제1권1호
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• pp.13-27
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• 2005

Simultaneous precision positioning and vibration suppression of a reciprocating flexible manipulator is investigated in this paper. The flexible manipulator is driven by a multifunctional active strut with fuzzy logic controllers. The multifunctional active strut is a combination of a motor assembly and a piezoelectric stack actuator to simultaneously provide precision positioning and wide frequency bandwidth vibration suppression capabilities. First, the multifunctional active strut and the flexible manipulator are introduced, and their dynamic models are derived. A control strategy is then proposed, which includes a position controller and a vibration controller to achieve simultaneous precision positioning and vibration suppression of the flexible manipulator. Next, fuzzy logic control approach is presented to design a fuzzy logic position controller and a fuzzy logic vibration controller. Finally, experiments are conducted for the fuzzy logic controllers and the experimental results are compared with those from a PID control scheme consisting of a PID position controller and a PID vibration control. The comparison indicates that the fuzzy logic controller can easily handle the non-linearity in the strut and provide higher position accuracy and better vibration reduction with less control power consumption.

• Tribology and Lubricants
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• 제30권2호
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• pp.116-123
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• 2014

The objective of this study is to model and simulate the nonlinear lubrication performance of the sliding part between the piston and cylinder wall in a hydrostatic swash-plate-type axial piston pump. A numerical algorithm is developed that facilitates simultaneous calculation of the rotating body motion and fluid film pressure to observe the fluid film geometry and power loss. It is assumed that solid asperity contact, so-called mixed lubrication in this study, invariably occurs in the swash-plate-type axial piston pump, which produces a higher lateral moment on the pistons than other types of hydrostatic machines. Two comparative mixed lubrication models, rigid and elastic, are used to determine the reaction force and sliding friction. The rigid model does not allow any elastic deformation in the partial lubrication area. The patch shapes, reactive forces, and virtual local elastic deformation in the partial lubrication area are obtained in the elastic contact model using a simple Hertz contact theory. The calculation results show that a higher reaction force and friction loss are obtained in the rigid model, indicating that solid deformation is a significant factor on the lubrication characteristics of the reciprocating piston part.

• Tribology and Lubricants
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• 제39권2호
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• pp.43-48
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• 2023

In this study, we investigate the tribological behavior of AISI 304 stainless steel pairs under deionized water and hexagonal boron nitride (h-BN) water dispersion lubrication. The specimen friction and wear properties are evaluated using a reciprocating ball-on-flat tribometer. The coefficient of friction remains nearly constant throughout the test under both lubricant conditions. The wear depth of the specimens under h-BN lubrication is smaller than that under deionized water lubrication, indicating the inhibition behavior of h-BN nanolubricants on direct metal-metal contacts. Optical micrographs and stylus profilometer measurements are performed to evaluate the severity of damage caused by the sliding motion and to determine the wear morphology of the specimens, respectively. The results show that h-BN nanolubricants does not have a significant effect on the friction behavior but demonstrates reduced wear owing to their trapping effect between the sliding interfaces. Moreover, scanning electron microscopy and energy-dispersive X-ray spectroscopy images of the specimens were acquired to confirm the trapping effect of h-BN between the sliding interfaces. The results also suggest that the trapped lubricants can distribute the contact pressure, reducing the wear damage caused by the metal-metal contact at the interface. In conclusion, h-BN nanolubricants have potential as an anti-wear additive for lubrication applications. Further investigation is needed to provide direct evidence of the trapping effect of h-BN nanoparticles between the sliding interfaces. These findings could lead to the development of more efficient and effective lubricants for various industrial applications.

• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1457-1469
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• 2002

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an Sl engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it Is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swir and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.227-231
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• 2001

Analysis of two-dimensional unsteady flows with a free surface in a rectangular container subject to a linear reciprocating force is performed by numerical and experimental methods. FVM is used for the numerical computation of the two-dimensional flows. We consider the surface tension as well as the viscous/elastic properties of the free surface. One-dimensional analysis as well as experiment is used in establishing the free surface properties. The steady recirculatory flow is visualized by a laser sheet. It is shown that the one-dimensional analysis provides useful informations associated with the free surface properties.

• Journal of Biosystems Engineering
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• 제23권5호
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• pp.491-498
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• 1998

Transplanting process during the tissue culture of potato seedlings is costly, since the cost of highly skilled labor working in the sanitary environment takes up about 60-70% of the production cost. The objective of this study was to develop a soft gripper of a transplanting robot system for the labor-saving tissue culture. The prototype of the soft gripper was consisted of power-transmitting part finger and plant contacts. The power transmitting part transformed the rotating motion of a step motor to the reciprocating motion of the finger. Plant stems used in the test were potato seedlings cultured for six weeks. The dimensional characteristics of cultured seedlings, the compressive strengths of the stems, the extractive force from the culture medium and the gripping force of the finger were measured. A proper gripping force was found to be 0.343N at the extractive force of 0.41N when the plant contacts were made of silicon. Sixteen plants out of 70 trials were tangled with others, resulting in the success rate of 77.1%.

• 대한기계학회논문집B
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• 제26권7호
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• pp.1014-1021
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• 2002

Analysis of two-dimensional secondary flows given by an oscillatory motion of a liquid with a free surface in a rectangular container subject to a linear reciprocating force is performed by numerical and experimental methods. FVM is used for the numerical computation of the two-dimensional flows. We considered the effects of the free-surface properties such as the surface tension and the dilatational viscosity. The boundary-layer analysis as well as an experiment is used in establishing the free surface properties. The secondary flow patterns are visualized by a laser sheet. It is shown that the secondary flow patterns predicted by the numerical methods are in good agreement with the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1048-1050
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• 2003

Recently, many linear motion generators and motors are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic con type loud speakers to stilting engine driven linear reciprocating alternators, compressors, textile machines etc. In this paper, we analyze the characteristics of tubular linear motor with Halbach and radial magnet array respectively. We already derived magnetic field solutions due to the PMs and to the currents and Motor thrust. On the basis of analytical field solutions, this paper deals with flux linkages and back emf. The results are validated extensively by comparison with finite element analyses. Then, this parer also presents thrust characteristics according to design parameters for each model.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.650-653
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• 2001

In recent the energy efficiency of a refrigerator has been restricted extremely. A compressor consumes a great portion of input power in a refrigerator. So it is necessary to develop a more efficient compressor in these days. The existing reciprocating compressor need to a crank shaft to convert the rotating motion to the straight motion and is not efficient. But the linear compressor using mechanic resonance is efficient but need a drive instead of a crank shaft to control a position accurately. However it is impossible to apply a stroke sensor practically because of the internal circumstance of compressor. In this paper, A new sensorless stroke control method using the current and voltage of linear compressor is proposed.