• Journal of the Korea Institute of Military Science and Technology
• /
• v.3 no.2
• /
• pp.231-243
• /
• 2000

This paper describes a simulation of secondary motion of piston assemblies using PISDYN by Ricardo. Motions of the piston, pin, rod and skirt are separately calculated, by integrating equations of motion for individual components and dynamic degrees of freedom. The effects of engine speed at full load and pin offsets on the piston assembly secondary motions, forces and friction were investigated in parametric study for 4-cylinder gasoline engine. Results show that lateral displacement and friction loss of the piston increase as a function of engine speed. The lateral motion of the piston is affected by the change in pin offset. The minimum friction loss for the condition of 4800rpm WOT occurs at a pin offset of 1.6mm.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.11
• /
• pp.1057-1063
• /
• 2012

A cycloid speed reducer is a type of the speed reducers. The cycloid speed reducer has a eccentric rotating motion and offset to avoid some problem of assembly, so it has a disadvantage for vibration. In this paper, a multi-body dynamic model is developed for a cycloid speed reducer and the dynamic behaviors of the reducer are investigated. The cycloid speed reducer consists of cycloidal plate gears, housing gear, input shaft, output pin and shaft, and eccentric bearings. Using a CAD program, each component of cycloid reducer is modeled based on the offset and multi-body simulations are performed using Recurdyn. As a result, the pin reaction force and the amplitude of bearing displacement are increased by the offset.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.12C
• /
• pp.268-272
• /
• 2001

In this thesis, PLVCO(Phase Locked Voltage Controlled Oscillator) using 24.42 GHz voltage controlled hair-pin resonator oscillator, Sequency divider, buffer amplifier, -10 dB directional coupler and phase detector is designed and fabricated for B-WLL. The PLVCO shows the oscillator output power of 16.5 dBm at 24.42 GHz, and phase noise of -76.3 dBc/Hz at 1001:Hz offset, -72.8dBc/Hz at 10 kHz offset from fundamental frequency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.5C
• /
• pp.530-534
• /
• 2002

In the thesis, For improving the Stability of VCHRO(Voltage Controlled Hair-pin Resonator Oscillator) the new structure using the parallel feedback of the second harmonic is proposed for self-phase locking effect. This module is composed of wilkinson divider, frequency doubler, directional coupler, and bandpass filter using a hair-pin resonator, which are integrated into miniaturized hybrid circuit. The module exhibits output power of 2.5 dBm at 19.5 GHz, -29.83 dBc fundamental frequency suppression and -76.52 dBc/Hz phase noise at 10 kHz offset frequency from carrier of center frequency 19.5 GHz.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.1 no.3
• /
• pp.22-33
• /
• 1993

A theoretical analysis of predicting the detailed motion of a piston-crank mechanism within piston-guide clearance is presented, and the analysis is applied to the piston motion in a gasoline engine. A piston movement program is developed to calculate the piston attitude relative to the bore, the piston to bore impact velocity and kinetic energy loss and the net transverse force acting on the piston. This paper presents the formulation of a set of differential equations governing the transverse and rotational motion of a piston. These equations of motion were solved by well established Runge-Kutta method. As a result of this study, it is possible to predict the effects of piston geometry and piston pin offset on a piston motion and kinetic energy loss.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1591-1598
• /
• 2002

This paper reports on the effects of crankshaft offset on the engine friction. The effects of crank offset are investigated through the theoretical analysis. In this study, the mathematical models are presented fer evaluationg the friction level of each engine parts. Crank offset influences on the side force acted on the piston pin and sliding speed of piston. Crank offset is very effective to reduce the piston skirt friction. With application of crank offset, total engine friction decreases at low engine speed, but that increase as engine speed increases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.4
• /
• pp.271-287
• /
• 2001

This paper has been made to investigate the thermal performance characteristics for the several types of layered aluminum heat sinks with offset-strip fin. Heat sinks with different fin height, fin length, number of fin layer and slanted fin are prepared and tested for natural convection as well as forced convection. The experimental results for layered heat sink(LHS) are compared to those for advanced pin fin heat sink (PHS) so that the appropriate heat sink can be designed or chosen according to the heating conditions. The overall heat transfer performances for LHS are almost comparable to those of PHS under natural convection, and become 1.2∼1.5 times as high as those of PHS under forced convection situation. This study shows that fin height and number of fin layer re important parameters, which have a serious influence on thermal performance for layered heat sinks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.7
• /
• pp.1210-1218
• /
• 2001

In this paper, A X-band voltage-controlled hair-pin resonator oscillator(VCHRO) is able to a local oscillator or a signal source in transmitter/receiver of a microwave communication system for mobile radar, is designed and fabricated In order to apply mobile radar system is used the hair-pin resonator stronger on shock or vibration than the dielectric resonator, and also, in order to improvement the phase noise and output power is used a system of serial feedback format A hair-pin resonator was simulated by momentum method of HP ADS and then a oscillator circuit was designed that operates at 10.525 GHz by nonlinear method in harmonic balance simulation. The HRO generated output power of 6.93 dBm at 10.525 GHz, phase noise of -57.74 dBc at 100 kHz offset from carrier and the 2'nd harmonic was suppressed -23.90 dBc.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.3
• /
• pp.234-239
• /
• 2013

There are many types of speed reducer for industrial uses. However the cycloid speed reducer is widely used in manipulators based on excellent performance of low backlash, high reduction ratio and compact size. It is essential to use precision speed reducer for accuracy of position controls on robot systems and electric vehicles. The cycloid speed reducer has a eccentric rotating motion and offset to avoid some problem of assembly, so it has a disadvantage for vibration. In this paper, a multi-body dynamic model is developed for a cycloid speed reducer and the dynamic behaviors of the reducer are investigated. The cycloid speed reducer consists of cycloidal plate gears, housing gear, input shaft, output pin and shaft, and eccentric bearings. Using a CAD program, each component of cycloid reducer is modeled based on the offset and eccentric. Multi-body simulations using Recurdyn and test using a rig tester are performed. As a result, the pin reaction force and the amplitude of housing displacement are increased by the larger offset and smaller eccentric value of cycloid reducer.

• KSTLE International Journal
• /
• v.3 no.2
• /
• pp.84-89
• /
• 2002

Clearance movements of engine piston are very related to the piston impact to the engine block as well as many tribological problems. Some of the major parameters that influence these kinds of performances are piston profiles, piston offsets and clearance magnitudes. In our study, computational investigation is performed about the piston movements in the clearance between piston and cylinder liner by changing the skirt profiles and piston offsets. Our results show that curved profile and more offset magnitude to thrust side have better performance that has low side impact during the engine cycle.