• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.165-172
• /
• 2003

This study aims to find frequency weighting curves for the evaluation of drivers' discomfort by vertical and rotational steering wheel vibration. Equal sensation curves, inverse of frequency weighting curves, were determined for the two kinds of vibrations respectively by using the sinusoidal signals with reference amplitudes from 0.2 to 0.4 m/s2 in the frequency range from 5 to 100 ㎐. Twelve subjects joined at the tests, and median values of the twelve judgments were used to determine the equal sensation curves. An experiment was followed to compare the relative sensation magnitude between the two kinds of equal sensation curves, which showed discomfort by the rotational vibration was 1.5 times of that by the vertical vibration at 50 ㎐.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.1
• /
• pp.105-111
• /
• 2010

In the field of 'Human Vibration', it has been interested subjects to make equal sensation curves related to translational and rotational direction of whole-body, hand-transmitted and head-transmitted vibration, etc. When we consider the vibration of a vehicle, the main factor is vertical whole-body vibration. Until now, most of equal sensation curves used to derive frequency weighting function had been made using Western people. However, because of the inherent differences (for example, characteristic and shape of body parts, muscular and cellular tissue) between the Western people and the Oriental people, equal sensation curves based on Oriental people might be required. Also, the weight differences between the samples which consist of average-weighted and over-weighted group might cause the difference of equal sensation curves. So, in this study, 20 male Korean people were used to find equal sensation curves subject to vertical whole-body vibration on seated posture. Among 20 males, an over weighted group consisted of 10 male persons and an average weighted group was the others. Integrating and analyzing the data of two groups, some of non-parametric tests such as 'The Wilcoxon Signed Rank Test' and 'The Mann Whitney U test' were used.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.6
• /
• pp.108-113
• /
• 2007

This study aims to find equivalent comfort contours, reciprocal of frequency weighting curves, for vertical steering wheel vibration. Psychophysical responses were measured from twelve male subjects by using magnitude estimation of relative discomfort due to vertical steering wheel vibrations of magnitude of 0.1 to 1.58 $m/s^2$ in the frequency range of 4 to 250 Hz. Relative discomfort were estimated with a reference vibration of 0.4 $m/s^2$ at 31.5 Hz. Equivalent comfort contours were produced from the median of sensation magnitudes judged by twelve subjects, which showed variation in the shapes with increase of vibration magnitude. A shape of the contour came close to the perception threshold curve with decrease of vibration magnitude. When the vibration magnitude increases, the shape changed close to those in the references of Hong and et al (2003). It is also recommended frequency weighting curves for vertical steering wheel vibration must be expressed as a function of vibration magnitude as well as frequency.

• International Journal of High-Rise Buildings
• /
• v.1 no.4
• /
• pp.283-300
• /
• 2012

Wind-induced vibrations of buildings can be perceived when movement of objects caused by the vibration is seen. However, movement of objects that would normally be expected to trigger visual perception of building vibrations is not necessarily seen in actual building environments. Therefore, to evaluate habitability to building vibrations, it is necessary to examine the influence of movement of objects on vibration perception taking into account probability of seeing the objects. As the first step in this study, those data necessary to estimate probability of vibration perception from seeing of swaying objects have been measured during normal activities in actual buildings. In addition, statistical analysis of the data has also been carried out. As the second step in this study, the probability distribution of vibration perception by visual sensation is estimated using the series of data measured in the first step. Probability of seeing object is considered in the estimated probability distribution.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.621-624
• /
• 2005

Among many auditory feelings for the vehicle interior noise, booming is considered as the most important nuisance to the passenger and developer. Because the main source of booming noise is a power train system including engine, in general, it consists of tonal components related to fundamental engine rotation and its harmonics including the firing frequency. Therefore, it is demanded to extract the effective tonal components only by using pitch extraction algorithm based on the place theory enable to find aurally relevant tonal components. However, there is a difference between booming sensation and pitch perception according to frequency change of tonal component. In this study, subjective listening test using a tracking method was performed to find the difference limen for just noticeable change of booming sensation in frequency. 20 Koreans and 10 Japanese were participated in this test and the results obtained from Koreans and Japanese were compared with each other. Finally, 5Hz was determined as the difference limen for just noticeable change of booming sensation in frequency, and by applying this value to booming analysis using pitch concept, it was confirmed that the degree of prediction of booming sensation was improved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.1048-1052
• /
• 2003

This study aims to derive frequency weighting curves for the estimation of driver's discomfort by steering wheel vibration in the vertical and rotational direction with respect to a steering column. Subjective tests for the determination of equal sensation curves, inverse of frequency weighting curves, for the two kinds of vibrations were performed using the sinusoidal signals with reference amplitudes from 0.2m/s$^2$ to 0.4 m/s$^2$ in the frequency range from 5㎐ to 100㎐. Twelve subjects joined at the tests, and median values of the twelve judgments were used to determine the frequency weighting curves. Second experiment was followed to determine relative magnitude between the two frequency weighting curves by direct comparison of discomfort due to the two kinds of vibrations at 50㎐, which showed discomfort by the rotational vibration was 1.5 times of that by the vertical vibration.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.10
• /
• pp.845-850
• /
• 2015

This study was designed to investigate the feasibility of utilizing an adaptation for selective elicitation of tactile sensations by means of transcutaneous electrical stimulation. We conducted the first experiment to investigate how the stimulation frequency affected the adaptation. Twenty healthy subjects participated in the second experiment to confirm our proposal that the perception intensity of the low-frequency vibration can be enhanced after a high-frequency adaptation, and vice versa. It was found that (1) a low-frequency stimulation did not adapt the nerve afferents responsible for the high-frequency vibration, (2) a high-frequency stimulation affected the nerve afferents responsible for the low-frequency vibration, but adapted to the pressure sensation more intensely, and (3) more than 62% of the subjects reported a more clear selective sensation after the adaptation had lessened or depressed the unwanted sensation. The observations showed that adaptation of the nerve afferent could be utilized for selective elicitation of tactile sensations.

• Journal of Preventive Medicine and Public Health
• /
• v.14 no.1
• /
• pp.75-80
• /
• 1981

Due to rapid industrialization and economic development, the occupational diseases have appeared as one of the social problems in Korea. Up until now little has been known about the prevalence rate, predisposing factors and symptomatology of the occupational disease due to localized vibration in Korea. The researcher intends to investigate the prevalence rate and affecting factors of the occupational disease due to localized vibration among rock-drillers in the anthracite mines. A total of 135 rock-drillers were interviewed and examined from May 15th to 31th, 1980. The results were revealed as follows; 1. The prevalence rate of the vibration syndrome among rock-drillers was 12.6%. 2. The latent period of the vibration syndrome was 6.8 years. 3. The prevalence rate of the vibration syndrome was not significantly different between smokers and non-smokers. 4. With the increase of total vibration exposure time, the prevalence rate of the vibration syndrome increased also. 5. The average vibration sensation threshold was high (6.4dB) in stage 1 of the vibration syndrome and low (-0.6dB) in stage 0. 6. The average pain sensation threshold was high (4.4g) in stage 1 of the vibration syndrome and low (2.5g) in stage 0.

• Archives of Plastic Surgery
• /
• v.32 no.1
• /
• pp.71-75
• /
• 2005

The purpose of this study is to assess abdominal sensation after free TRAM flap for breast reconstruction. 74 patients underwent breast reconstruction with free TRAM flap by authors and were followed up to check the sensation on abdomen following the surgery at the out patient clinic. They are compared with 20 female volunteer controls. Abdomens were divided into 13 zones, and assessed for superficial touch, superficial pain, temperature, two-point discrimination, and vibration. For all five sensory modalities, subjects were found to have decreased sensation in the umbilical and infraumbilical regions. This was statistically significant compared with controls. Division following pedicle dissection showed more reduction of sensation than non-dissection side. Both Inguinal areas below the donor site closure also showed markedly decreased sensation. Sensation on most area of abdomen recovered in postoperative 1 year, however, there were remained hypoesthesia in umbilical and infraumbilical area after post operative 1 year. This study clearly demonstrates that there is a significant and persistent reduction in abdominal sensibility following free TRAM flap surgery.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.535-539
• /
• 2011