• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 추계학술대회 논문집
• /
• pp.613-616
• /
• 2012

A multi body simulation (MBS) model is developed for predicting the impact harshness of the vehicle. Impact harshness is the vehicle performance to evaluate the impulsive vibration behavior during driving over an obstacle of the road. Thus, the approach is simulated on the time domain for considering the transient behavior of the vehicle. The validity of vehicle component modeling of bushes, dampers and structure flexibilities is verified. The simulations are compared with the test results in both of vertical and longitudinal directions. In particular, the vertical vibration of the vehicle is significantly affected by the body flexibility. Through the sensitivity analysis, main factors for the impact harshness performance are investigated.

• 소음진동
• /
• 제9권3호
• /
• pp.577-586
• /
• 1999

Estimation of damping ratio for vibration signals measured on the passenger car's sear is useful for the objective evaluation of impact harshness in car. The vibratio signal is a transient signal represented by many coupled modes of suspension system. Wavelet transform automatically decouples these modes in the time-frequency domain. Damping ratios for decoupled modes are obtained by logarithmic treatment for the Wavelet transformed signal. The objective evaluation using Wavelet transform has been well corresponded with subjective evaluation done by skilled engineers.

• 복식문화연구
• /
• 제5권3호
• /
• pp.151-158
• /
• 1997

This study was to find out the differences of the characteristics on chitosan from source, the crab and the shrimp. Chitosan was depolymerized in NaBO₃·4H₂O under various reaction time and temperature. 4 Chosen chitosan dissolved in acetic acid and treated to cotton fabrics. The cotton fabrics treated with chitosan showed an exellent antibacterial activity irrespective of the viscosity. Stiffness of the treated cotton fabrics increased 3∼8 times than untreated cotton fabric, it gives harshness to treated cotton fabrics, it gives harshness to treated cotton fabrics like linen. Air permeability of the treated cotton fabrics increased. Stiffness and air permeability are respective to viscosity of the chitosan.

• Journal of Mechanical Science and Technology
• /
• 제15권5호
• /
• pp.535-543
• /
• 2001

This paper presents the ride comfort analysis of a vehicle based on wavelet transform. Traditionally, the objective evaluation of impact harshness is based on the vibration dose value (VDV) and frequency weighting method. These methods do not consider the damping effect of the suspension system of a vehicle. In this paper, the damping is estimated using wavelet transform based on Morlet mother wavelet and its effect is considered for the subjective evaluation of impact harshness of a car.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.1710-1715
• /
• 2000

Estimation of damping ratio for vibration signals measured on the passenger car's seat is useful for the objective evaluation of impact harshness in car. The vibration signal is a transient signal represented by many coupled modes of suspension system. Wavelet transform automatically decouples these modes in the time-frequency domain. Damping ratios for decoupled modes are obtained by logarithmic treatment for the Wavelet transformed signal. The objective evaluation using Wavelet transform has been well corresponded with subjective evaluation done by skilled engineers.

• Journal of Mechanical Science and Technology
• /
• 제17권7호
• /
• pp.958-965
• /
• 2003

Structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of ride and handling, durability, noise/vibration/harshness (NVH), crashworthiness and occupant safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer In this study, we used the virtual proving ground (VPG) approach for obtaining the dynamic characteristics. The VPG approach uses a nonlinear dynamic finite element code (LS-DYNA3D) which expands the application boundary outside the classic linear static assumptions. The VPG approach also uses realistic boundary conditions of tire/road surface interactions. To verify the predicted dynamic results, a single lane change test has been performed. The prediction results were compared with the experimental results, and the feasibility of the integrated CAE analysis methodology was verified.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 I
• /
• pp.450-454
• /
• 2001

The aim of the study is to develope an objective index for the evaluation of vehicle ride comfort using the measured vehicle accelerations. The equation of the index was derived from the correlation analysis of subjective ratings on selected vehicles and the reduced measure of the vehicle motions. First whole procedure of from the measurements to the calculation of the perceptual vibration was developed. Test condition of both the vehicle speed and the road condition was selected so as to maximize the reliability of the index. This paper suggested the equation of the objective ride index on vibration harshness, of which expected error is about 0.3 in 10 scale of subjective rating at 95％ of the significance level.

• 대한음성언어의학회:학술대회논문집
• /
• 대한음성언어의학회 1996년도 제6회 학술대회 심포지움
• /
• pp.87-87
• /
• 1996

객관적인 검사도구인 Dr. Speech Science(DSS)의 음성평가 결과가 갖는 의미를 알아보고자 이 연구를 하였다. 성대결절환자 여자 성인 25명을 대상으로 DSS를 이용한 음성평가와 청각심리적 검사방법인 GRBAS와의 관계를 비교 분석하였다. 청각심리적 검사인 GRBAS의 0, 1, 2, 3의 각 Grade에 따라 DSS의 음성평가의 결과와 비교하였다. DSS의 음성평가 결과로서 Grade가 0, 1, 2인 경우 총 15례중 1례를 제외한 모든 경우에 있어서 hoarseness, harshness, breathiness항목에서 정상소견을 나타냈으며 Grade가 3인 경우에는 총 10례 중 6례에서 hoarseness, harshness, breathiness항목에서 정상소견을 나머지 4례에서는 hoarseness에서 slight한 정도를 보여주었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.695-700
• /
• 2003

This paper dealt with friction-induced vibrations in engineering practice, specifically arising at the moment of counterturn of two friction surfaces. The harshness of the vibrations are attributed to the sharp change of the friction coefficients from kinetic to static near zero relative velocity, which is one of the examples of the stick slip. But the experimental results and numerical analysis of piston and cylinder operation showed that transition of the friction coefficient from kinetic to static is insignificant in vibrations. Dry friction itself dominates the harshness of vibrations. This study shows that how dry friction triggers the vibrations and demonstrates the effect of sharp transition from kinetic to static friction coefficient on the vibrations.

• 소성∙가공
• /
• 제12권7호
• /
• pp.654-661
• /
• 2003

A monobloc TDS(Tube Drive Shaft) has been developed by using the rotary swaging process which is one of the incremental forming process. In order to estimate the developed TDS performance characteristics such as natural frequency, strength, stiffness and mass, finite element analysis has been carried out using commercial software, MSC/NASTRAN. The calculated performance characteristics have been compared with analysis results of SDS(Solid Drive Shaft) to know how much improve the performance characteristics. Also the sensitivity analyses of design parameters for the tube length and diameter have been performed. From the analysis results, it was found that the TDS allowed for a high frequency and could be designed to be much lighter than SDS. This advantage can give possibility to tune the NVH (Noise-Vibration-Harshness) characteristics.