• Journal of Biomedical Engineering Research
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• v.34 no.1
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• pp.40-45
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• 2013

The conventional simulators used the expensive commercial artificial heart with a limited performance, and focused on replicating the heart function. The arterial pressure is the key factor of the cardiovascular disease. The purpose of this study is to develop a simulator focused on the pressure wave. The simulator is composed of a step motor, slider-crank mechanism, piston-cylinder, two check valves, a elastic tube, and two reservoirs. With the changes of design parameters, the functions of the simulator were evaluated. The simulator shows the good agreement of the characteristics of the cardiovascular system.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.686-692
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• 1999

For the purpose of increasing compressed air pressure higher than 30bar lightening weight and decreasing installation area of air compressor used for shipboard and industrial power plant it is necessary to arrange its cylinders as a w-type or v-type construction multi-stage compression pro-cess more than two stages and to increase its operation speed higher than 1200rpm In this recip-rocating type air compressor operated in high speed having a crank mechanism and complicate cylinder arrangement there is a vibration problems which can be solved by balancing its recipro-cating parts with balance weight and approriate arranging of cylinder's arrangement angles.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.243-246
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• 2008

The press machine is actuated by the rotating motion of crank shaft and the reciprocating motion of slide. In recent years, unbalance moments and forces to the main frame attract many researches, as press technology becomes more miniaturized, precise, and rapid. In order to control vibrations caused by the rapid motions of the crank shaft and slide, this paper studies a resolution reducing the unbalance at the high speed knuckle press.

• Journal of Biosystems Engineering
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• v.37 no.5
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• pp.279-286
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• 2012

Purpose: This study has been conducted to investigate the applicability of motion analysis of tillage blade for estimation of tillage characteristics of crank-type and rotary-type rotavators. Methods: The interrelation between tillage traces from motion analysis and field test results including rotavating depth, pulverizing ratio and inversion ratio at the same work conditions were analyzed for both crank-type and rotary-type rotavators. The work conditions include working speed of prime mover tractor and PTO speed of rotavators. For the motion analysis, joint conditions of main connecting component were specified considering the actual working mechanism of rotavator. Results: There were important correlations for the trend between motion analysis and field test results. Conclusions: Although further study is needed for applying motion analysis to estimate the accurate tillage related parameters such as rotavating depth, the soil pulverizing ratio and inversion ratio, it could be used to compare the tillage characteristics of various rotavators quickly and simply.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1018-1025
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• 2003

The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method, the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60% of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.709-717
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• 2004

The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method. the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60 ％ of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.

• Structural Engineering and Mechanics
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• v.90 no.1
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• pp.97-106
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• 2024

This paper presents a significant contribution to aided design by conducting an analytical examination of geometric links with the aim of establishing criteria for assessing an analogy measure of the extrinsic geometric and kinematic characteristics of the Variable Compression Ratio (VCR) engine with a Geared Mechanism (GBCM) in comparison to the existing Fixed Compression Ratio (FCR) engine with a Standard-Reciprocating Crankshaft configuration. Employing a mechanical approach grounded in projective computational methods, a parametric study has been conducted to analyze the kinematic behavior and geometric transformations of the moving links. The findings indicate that in order to ensure equivalent extrinsic behavior and maintain consistent input-output performance between both engine types, precise adjustments of intrinsic geometric parameters are necessary. Specifically, for a VCR configuration compared to an FCR configuration, regardless of compression ratio and gearwheel radius, for the same crankshaft ratios and stroke lengths, it is imperative to halve lengths of connecting rods, and crank radius. These insights underscore the importance of meticulous parameter adjustment in achieving comparable performance across different engine configurations, offering valuable implications for design optimization.

• Journal of Biosystems Engineering
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• v.38 no.2
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• pp.73-80
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• 2013

Purpose: This study was conducted to compare tillage and loads characteristics of three types of rotavators in farmland working condition of Korea. Methods: Tillage operations using three types of rotavators, i.e. rotary-type, crank-type and plow-type, were carried out in a dry field of Korea. The same prime mover tractor was used for driving three types of rotavators, and under several operational conditions, tillage characteristics such as actual working speed, rotavating depth, rotavating width, actual field capacity, flow of tilled soil, soil inversion ratio, and pulverizing ratio were measured. In addition, loads characteristics like torque and required power of Power Take-Off (PTO) shaft were calculated. Results: The average rotavating depth was smaller than the nominal value for all rotavators, and the difference was the greatest in the plow-type rotavator. Nevertheless, the plow-type rotavator showed the largest rotavating depth. The rotavating width was the same as the nominal value of all rotavators. The flow of tilled soil at the same operational conditions was the greatest in the plow-type rotavator and was the smallest in the rotary-type rotavator. In the most commonly used gear conditions of L2 and L3, the average soil pulverizing ratio was the greatest in the rotary-type rotavator, and followed by crank-type and plow-type rotavators in order. In the gear L2 and L3, the plow-type rotavator also had the lowest average soil inversion ratio while the rotary-type and crank-type rotavators had the same soil inversion ratio each other. The average torque and power of PTO shaft in the gear L2 and L3 were the highest in the plow-type rotavator. The load spectra of PTO shaft applying rain flow counting method and Smith-Waston-Topper equation to the measured torque showed that the modified torque amplitude was the greatest in the crank-type rotavator. This may come from the large torque fluctuation of crank-type rotavator during tillage operations. Conclusions: The three types of rotavators had different tillage and loads characteristics. The plow-type rotavator had the deepest rotavating depth, the smallest soil inversion ratio, the largest soil pulverizing ratio and required PTO power. Also, the crank-type rotavator showed a large torque fluctuation because of their unique operational mechanism. This study will help the farmers choose a suitable type of rotavator for effective tillage operations.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.563-572
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• 2001

With the results of calculation for natural frequencies the reponses of forced coupled vibration of propulsion shafting system were investigated by the modal analysis method. For the forced vibration response analysis, the axial exciting forces, the axial damper/detuner, propeller exciting forces and damping coefficients were extensively considered. As the conclusion of this study, some items are cleared as follows.-The torsional vibration amplitudes are not influenced by the radial excitation forces of the crank shaft. -The axial vibration amplitudes are influenced by the tangential exciting forces as well as the radial exciting forces of the crank shaft. The increase of the amplitudes is observed in the speed range at the neighbourhood of any torsional critical speed. 1The closer the torsional and axial critical speed. the larger coupling effect becomes. -The axial exciting force of propeller is relatively strong comparing with axial exciting forces of cylinder gas pressure and oscillating inertia of reciprocating mechanism. Therefore, the following conclusions are obtained. -Torsional vibration calculation with the classical one dimensional model is still valid. -The influence of torsional excitation at each crank upon the axial vibration is improtant. especially in the neighbourhood of a torsional critical speed. That means that the calculation of axial vibration with the classical one dimensional model is inaccurate in most of cases.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1365-1373
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• 1994

Elasto-dynamic deformation of flexible linkage mechanism was analyzed using the finite element method. A computer program was constructed and applied to analyze a specific crank-level 4-bar mechanism, in which the elasto-dynamic deformation of the mechanism system was obtained using mode superposition method in the case of constant input speed and the effect of geometric stiffness on the mechanism is included. Experimental verification of numerical results was conducted by measuring the elasto-dynamic deformation of mid-points of coupler and lever for the 4-bar lingkage mechanism using high speed camera and image data processing systeem. For the elasto-dynamic deformation at the lever mid-point, the numerical results including geometric stiffness almost agree with the experimental ones. However, the numerical results excluding geometric stiffness good agree with the experimental ones at the couper mid-point.