• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1496-1502
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• 2012

The fuel pump mounted on the engine in the vehicle is consist of the outer and inter rotors, and which inhales fuel from the inlet port and supplies it to the outlet port. In this study, it is carried out the analysis and test of the fuel pump with rotors to evaluate its performance. It is analyzed the flow characteristics of the fuel pumps with numerical simulation in their inlet-outlet angles of 0, 15, 30 degree. After it is determined whether it has the best flow characteristics, its vibration characteristics is analyzed. The flow rate of a pump in the inlet-outlet angles of 0 degree is 191.0 LPH(Liter per hour) which is the largest. and its vibration is calculated to be 0.866 $^m/s^2$. In the results of vibration test, it is known that the vibration of the research pump is smaller than that of the existing one. And the natural frequencies of two pumps is nearly same. Therefore it is known that the performance of the research pump is superior.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.584-589
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• 2001

This paper presents the dynamic parameter design optimization of a suspension seat system using the genetic algorithm. At first, an equivalent 1-D.O.F. mass-spring-damper model of a suspension seat system was constructed for the purpose of its vibration analysis. Vertical vibration response and transmissibility of the equivalent model due to base excitations, which are defined in the ISO's seat vibration test codes, were computed. Furthermore, seat vibration test, that is ISO's damping test, was carried out in order to investigate the validity of the equivalent suspension seat model. Both analytical and experimental results showed good agreement each other. For the design optimization, the acceleration transmissibility of the suspension seat model was adopted as an object function. A simple genetic algorithm was used to search the optimum values of the design variables, suspension stiffness and damping coefficient. Finally, vibration ride performance test results showed that the optimum suspension parameters gives the lowest vibration transmissibility. Accordingly the genetic algorithm and the equivalent suspension seat modelling can be successfully adopted in the vibration ride quality optimization of a suspension seat system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.89-94
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• 1998

With increasing demands on automatic and high-capability manufacturing, the dynamic performance of machine tools becomes more and more important. In this paper, the correlation between dynamic compliance of the cutting system and the commencing point of chatter vibration in turning is checked by impulse excitation method and cutting tests for some cutting system. The correlation between chucking conditions of workpiece and the commencing point of chatter vibration is clarified, and it is proven that there is a mutual relations between them. Chatter vibration commenced at certain level of dynamic compliance of the cutting system regardless of the kind of the system. It shows the possibility of dynamic performance test of a lathe by means of impulse excitation method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1313-1316
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• 2006

Demands of high volume dry vacuum pumps on the domestic semiconductor and LCD industries are rapidly increasing as the size of wafers and LCD is increasing. This study introduces a new experimental setup for testing the reliability of vacuum pumps. The test system was designed to measure the acoustic pressure and mechanical vibration levels simultaneously. It is shown that the test system enables the analysis and evaluation of the performance of dry pumps under the different gas-load conditions. Detailed experimental result are shown to enable us to examine the characteristics and performance of dry pumps.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.94-103
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• 2016

For elevated railway station on which track is connected with superstructure of station, structural vibration level and structure-borne-noise level has exceeded the reference level due to structural characteristics which transmits vibration directly. Therefore, existing elevated railway station is in need of economical and effective vibration reduction method which enable train service without interruption. In this study, structural vibration non-transmissible system which is applied to vibroisolating material for column member is developed to reduce vibration. That system is cut covering material of the column section using water-jet method and is installed with vibroisolating material on cut section. To verify vibration reduction effect and structural performance for structural vibration non-transmissible system, impact hammer test and cyclic lateral load test are performed for 1/4 scale test specimens. It is observed that natural period which means vibration response characteristics is shifted, and damping ratio is increased about 15~30% which means that system is effective to reduce structural vibration through vibration test. Also load-displacement relation and stiffness change rate of the columns are examined, and it is shown that ductility and energy dissipation capacity is increased. From test results, it is found that vibration non-transmissible system which is applied to column member enable to maintains structural function.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.347-352
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• 2013

Seoul National University Flap (SNUF) blade is a small-scaled rotor blade incorporating a small trailing-edge flap control surface driven by piezoelectric actuators at higher harmonics for vibration attenuation. Initially, the blade was designed using two-dimensional cross-section analysis and a geometrically exact one-dimensional beam analysis, and material configuration was finalized. Flap deflection angle of ${\pm}45^{\circ}$ was established as the criterion for better vibration reduction performance based on an earlier simulation. Flap linkage mechanism design is carried out and static bench tests are conducted to verify the flap actuation mechanism performance. Different versions of test beds are developed and tested with the flap and chosen APA 200M piezoelectric actuators. Through significant improvements, a maximum deflection of ${\pm}3.7^{\circ}$ was achieved. High frequency experiments are conducted to evaluate the performance and transfer function of the test bed is determined experimentally. As the static tests are almost completed, rotor power required for testing the blade in whirl tower (centrifugal environment) is calculated and further preparations are under way.

• Physical Therapy Rehabilitation Science
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• v.2 no.2
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• pp.115-118
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• 2013

Objective: Whole body vibration training is a relatively new approach for enhancement of muscle strength, physical performance, and balance. The aim of this study was to assess the effect of unilateral whole body vibration training. Design: One group pretest-posttest design. Methods: Sixteen healthy, physically active volunteers participated in this study. Whole body vibration was applied with a frequency of 20 Hz and an amplitude of 3 mm for 3 minutes. Muscle performance and static balance were assessed before and after unilateral whole body vibration training. One leg standing broad jump test was measured to determine muscle performance which is closely linked to lower extremity muscle function. The good balance system was used in evaluation static balance. All test were measured 3 times and the average value was analyzed. Results: Jumping length was significantly improved by 0.11m in all participants after intervention (p<0.05). Among static parameters, significant results were observed where in the eyes opened condition, X-speed (medial-lateral sway) changed from 4.20 mm/s to 4.95 mm/s, Y-speed (anterior-posterior sway) changed from 5.77 mm/s to 6.54 mm/s and velocity moment changed from $12.77mm^2/s$ to $13.57mm^2/s$ (p<0.05). In the eyes closed condition, X-speed changed from 4.34 mm/s to 4.85 mm/s, Y-speed changed from 7.84 mm/s to 8.16 mm/s and velocity moment changed from $16.03mm^2/s$ to $16.11mm^2/s$ (p<0.05). Conclusions: Immediate unilateral whole body vibration improved muscle performance but impaired static balance in young adults.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.648-654
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• 2007

This paper presents the result of a comparison study to evaluate the performance of several semi-active control algorithms for use with large-scale MR damper applied to a building structure under seismic excitation using real-time hybrid test method. Recently, a variety of semi-active control algorithm studies are developed and generally evaluated the performance by using numerical analysis. In this paper real-time hybrid test method was applied to performance evaluating of semi-active control algorithms including a clipped optimal algorithm and the modulated homogeneous friction algorithm.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.1
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• pp.24-32
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• 2015

Pulse tube-type spaceborne cryocooler is widely used to cool down the infrared sensor of observation satellites. However, such cryocooler also generates micro-vibration which is the one of main sources to seriously affect the image quality during its on-orbit operation. Therefore, to comply with the mission requirement of high resolution observation satellite, additional technical efforts have been required. In this study, we proposed a spaceborne cryocooler passive vibration isolator using SMA mesh washer, which guarantees the structural safety of both the micro-vibration disturbance source and itself under harsh launch vibration loads without an additional holding mechanism and the micro-vibration isolation performance on orbit environment. To verify the micro-vibration isolation performance of the proposed vibration isolator, we performed the micro-vibration isolation measurement test using the dedicated micro-vibration measurement device proposed in this study.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.781-787
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• 2016

We introduce FEST (Flight Environment Simulation Test) procedures for precise guided missiles to reliably improve systems. Flight vibration specification was established based on power spectral density curves calculated from flight test data of a high speed precise guided missile. A FEST pre-profile was developed according to flight vibration specification and delivered to a precise guided missile assembly. Vibration responses were measured by installing accelerometers on electronic components vulnerable to dynamic forces. The FEST profile was adjusted by comparing the vibration responses and the flight vibration specification. Subsequently, the FEST profile was repeatedly modified through trial and error, because the responses were similar to the flight environment. The modified FEST profile enabled performance testing of assembled precise guided missiles under simulated flight conditions on the ground, where unexpected errors could be corrected before the flight tests, leading to cost and risk reduction in the development of the precise guided missile system.