Objective: The objective of this study is to examine the characteristics of the research on human vibration in Korea. Background: There have been relatively less interests in vibration than other ergonomic factors in Korea. However, the importance of vibration is increasing as industry and everyday life are more mechanized. Method: This study reports the results of the literature review on the papers about human vibration published in ergonomics-related domestic journals. Results: It was found that more studies have been done on local vibration than on whole body vibration. Diverse topics have been studied in ergonomics community. Conclusion: Further cutting-edge studies are expected than classical safety and health related ones. Application: Some suggestions were proposed hopefully helpful to colleague ergonomists for future research.

Objective: The purpose of this study is to review the hazards of whole body vibration(WBV) and prevent human injuries due to WBV. Background: Vibrations that shake the whole body in vehicles and vessels is WBV. Vibration at a specific frequency, and intensity in the human body can act as a hazard. But, it has not yet done enough research about effects of WBV. Method: We analyzed and reviewed occupational or ergonomic papers published past 30 years. Results: Exposure to whole body vibration can cause permanent physical injury or damage of the nervous system. In addition, it may cause problem in the cardiovascular system, digestive system, musculoskeletal system, endocrine system, reproductive system, and psychological system. The effect of vibration depends on its acceleration, duration, frequency, and direction. Conclusion: WBV-exposed human body experience a high risk of some illnesses such as lumbar spinal disorders. Some workers(bus drivers, truck drivers and heavy equipment operators) are the high risk population exposed to WBV. Application: The results of this study might help to judge and prevent occupational disease caused by WBV.

Objective: The aim of this study is to understand health effect of hand-arm transmitted vibration. Background: Electronic vibration tools have been used in many industries. These tools evoke hand-arm transmitted vibration that cause hand-arm vibration syndrome. Method: Various papers on the hand-arm transmitted vibration and its health effects have been reviewed to know what health effect caused. Results: Hand-arm transmitted vibration causes circulatory, neural, musculoskeletal and other disturbance. Conclusion: The previous studies focused on the epidemiology and physiology for hand-arm transmitted vibration. So, now we should focus on a prevention and guideline of hand-arm transmitted vibration. Application: These results can be used to know health effect of hand-arm transmitted vibration.

Objective: The aim of this study is to review and summarize human vibration measurement process, and necessity and methods of frequency weightings for human vibration. Background: Prolonged human exposure to hand-arm vibration and whole-body vibration can result in a range of adverse conditions and the development of occupational diseases such as vibration white finger. For preventing these adverse effects, it is important to correctly apply human vibration measurement process. Method: This manuscript was based on the review and summary of mechanical and human vibration relevant texts, academic papers, materials obtained through web surfing. Results: This manuscript summarizes human vibration measurement process described in ISO standards and relevant texts. The sensitivity of the human body to mechanical vibration is known to be dependent on both the frequency and direction of vibration. To take this into account, varying frequency weighting functions have been developed, and RMS frequency-weighted accelerations are used as the most important quantity to evaluate the effects of vibration on health. ISO provided nine frequency weighting functions in the form of curves and tables. Researches on frequency weightings are focused on development and validation of new frequency weightings to truly reflect the relationship between vibration exposure and its adverse effects. Application: This would be useful information for systematically applying human vibration measurement and analysis process, and for selecting appropriate frequency weighting functions.

Objective: The aim of this study is to review the literatures on the regulation, standard and guideline for the human vibration in Korea and other countries. Background: This review can be used to prevent various diseases caused by the human vibration as a basis for the development of the policy. Results: In Korea, the general employers' duties related to human vibration are set forth the Health Measures(Article 24) in the Occupational Safety and Health Act. And then an employer shall take measures to protect the health of the workers concerned by improving other working conditions relating to working hours for the vibration prevention measures referred to in Article 24 of the Act. The European Union adopted a Directive in 2002 on minimum requirements for the health and safety of workers exposed to vibration. New Regulations on Vibration at Work will be introduced in Great Britain on 2005 to implement the Directive. In the U.S., both ANSI and ACGIH adopted the ISO standard for measurement and suggested exposure action and limit values. In Japan, the Ministry of Labor decided that the vibration syndrome among operators of rock drills and riveters etc. could be included in an occupational disease(1947). In addition, ISO standard was based on proposals and draft documents of many countries such as U.K, Japan and European, etc. Conclusion: In Korea, Occupational Safety and Health Act prevent vibration to health, but do not include exposure limits. It is therefore important to consider the new duties regarding to vibration risks added to the general duties.

Objective: The aim of this study is to provide a current knowledge of the multiple issues regarding motion effects on crew performance. Background: The motions of the ship may create motion sickness, nausea and vomit. Also, these motions also disturb the balance of crew members, increase the energy expenditure of crew for shipboard work, and result in increased levels of injury and fatigue. However, the motion effects of the ship on crew performance has not been thoroughly investigated. Method: Participants(N=10) were engaged in an experiment in 2 experimental environments(training ship and ship handling simulator) and 2 navigational conditions(day and night). The COP(Center of Pressure) data were recorded as an objective measure of postural balance control and the SSQ(Simulator Sickness Questionnaire) was used as a subjective measure of sickness. Results: The results showed that COP has a no significant difference based on experimental environments, but significant effect on SSQ. Conclusion: During the virtual simulator navigation, subjects showed significant SSQ level changes, which included decreased SSQ data. But, there is no significant difference of COP between training ship and ship handling simulator. Application: The results of this study could be applied to the next generation of ship design to decrease effect of motion at sea and to increase performance of ship crew.

Objective: This study measured and evaluated the characteristics of the whole body vibration experienced in some coal-fired power plant in Korea. Background: Few studies have been carried out in Korea about the effects of whole body vibration of power plants on humans. Method: The evaluation scheme suggested by the Law of Noise and Vibration Control was applied. Results: It was found that 28.9% of total measurement points were above the limit suggested by the law. Conclusion: Many workers are exposed to whole body vibration during their job completion, and more efforts should be applied to prevention and control of the plat vibration.

Objective: This research measured physiological and psychological effects of Vibroacoustic stimulation(VA) to scapular and sacrum of supine position on the mattress. Background: When vibroacoustic stimulation applies to human body, it has a positive influence on physiological and psychological effects by stimulating the organs, tissues and cells of whole body. Method: This experiment was conducted to 10 normal males in two conditions: no stimulation and vibroacoustic stimulation. No stimulation experiment was executed as a supine position for 30 minutes without any vibrational stimulus, while vibroacoustic stimulation was transmitted by the vibrational speaker, which uses 40Hz frequency. Subjects had a laser Doppler flowmeter probe in scapular, sacrum, and also had 8 channel electroencephalogram(EEG) measurement sensor in the scalp. Blood pressure and skin temperature were measured in two conditions with an underlying posture for 30 minutes. Additionally, blood flow rate and EEG were measured before and after for two minutes on two conditions. Results: According to the vibroacoustic stimulation, blood flow rate and skin temperature were increased, while blood pressure was decreased. When using vibroacoustic stimulation compared to no stimulation, blood flow rate went approximately two times higher, and skin temperature also higher 3~4 times. Furthermore, the relative alpha power of brain wave was significantly increased when we applied to vibroacoustic stimulation. Conclusion: This experiment tested the VAT embedded in mattress in two conditions. According to this experiment, VAT decreases blood pressure, improves not only a physiological effect on blood flow rate as well as skin temperature, but also psychological functions by increasing relative alpha power. Application: The results of the publishing trend analysis might help physiological and psychological effects of vibroacoustic stimulation.

Objective: The aim of this study is to investigate the gender-differences in vibrotactile responses(sensitivity and displeasure) of residual forearm simulated by vibration stimulation in upper limb(trans-radial) amputees. Background: Several studies have reported that vibration stimulation using the haptic vibrator is one the most effective methods for delivering sensation to an amputees. However, few studies have reported the perception to haptic vibratory stimulus, particularly sensitivity and displeasure. Method: We set up a custom-made vibration stimulation system that included 6 actuators(3 medial parts and 3 lateral parts) and a graphical user interface(GUI)-based acquisition system to investigate changes in residual somatosensory sensibility and displeasure in the forearm of upper limb(trans-radial) amputees. Vibration actuators were attached at the 25%-point on the proximal forearm. Stimulation with 32Hz, 64Hz, or 149Hz of frequency was used for the sensitivity tests and with 32~257Hz of frequency was used for the discomfort experiments. The subjective responses were evaluated on a 10 point scale. Results: The results showed that vibrotactile sensory perception in male amputees were higher than that in female amputees. In male amputees, the response at lateral area of forearm was the most sensitive than medial area; but, female amputees showed similar sensitive areas. Subjects did not experience any discomfort during vibrotactile stimuli. Conclusion: Vibrotactile response in the amputees was dependent on gender as well as area stimulated by vibration. Application: The results might contribute to develop the vibrotactile feedback system for the amputees.

Objective: This study investigates the influences of vibrations on hedonic satisfaction based on four kinds of perceptions (perceived ease of use, perceived usefulness, perceived enjoyment, cognitive concentration) when mobile gaming. Background: As mobile gaming is becoming more and more popular for smartphone users, they might want to have more hedonic satisfaction instead of focusing on traditional usability criteria such as efficiency, effectiveness, and satisfaction. Method: We conducted a human-factors experiment with 35 male subjects to evaluate hedonic satisfaction in the mobile game configured by 7 vibration types having different levels of intensity and length. Results: The results revealed that the use of vibration significantly increases the perceived ease of use, perceived usefulness, and cognitive concentration. In addition, the intensity of vibration makes differences of perceived usefulness and cognitive concentration. Conclusion: Vibration can be effectively used to improve hedonic satisfaction of smartphone users in mobile gaming when they are not allowed to turn the sound effects on. Application: This study helps game designers effectively provide vibration feedback of mobile games for smartphone users.

Objective: The aim of this study is to investigate the effects of design parameters of vibrotactile signals on semantic association with transmitted information conveying different meanings. Background: As information communication relying on human visual channel becomes excessive, the utility of vibrotactile signals is being interested as a substitute measure of delivering information. Properly designed hapticons may relieve burden of visual communication by rendering distinct and meaningfully compatible haptic sensations. Method: A typical Kansei engineering approach was adopted in this study. Ten most distinctive hapticons were selected among those having different frequencies and amplitudes. Associations between the hapticons and twenty four pairs of adjectives used to describe the state of automobile in control were gathered from thirty subjects using semantic differential scales. Results: The selected pairs of adjectives were summarized by factor analysis into two semantic dimensions named 'Awareness' and 'Directionality'. The experimental hapticons matched with the semantic dimensions were presented as a haptic emotion map. Conclusion: The results from this study support that frequencies and amplitudes of haptic signals play important roles in arousing different human perceptions regarding the two haptic emotional dimensions. Application: Properly designed hapticons with respect to the contents of transmitted information will increase human operator's situation awareness as well as system performance. The result from this study can be used to develop standardized hapticons for active haptic communication.

Objective: This paper studies the method of measuring whole-body vibration in the car and terms associated. Background: Human exposure to vibration can be broadly classified as localized and whole-body vibration. The whole-body vibration affects the entire body of the exposed person. It is mainly transmitted through the seat surfaces, backrests, and through the floor to an individual sitting in the vehicle. It can affect the comfort, performance, and health of individuals. Method: Human responses to whole-body vibration can be evaluated by two main standards such as ISO 2631 and BS 6841. The vibration is measured at 8 axes - three translations at feet, 3 translations of hip and two translations of back proposed by Griffin. B&K's sensors used in this study are the 3-axes translational acceleration sensor to measure the translational accelerations at the hip, back and foot. Results: The parameters associated with the whole-body vibration in the car are frequency weightings, frequency weighted root-mean-square, vibration dose values, maximum transient vibration value, seat effective amplitude transmissibility, ride values and ride comfort. Conclusion: Studied the evaluating methods of vibration exposure and ride comfort. Application: Evaluation of whole-body vibration in the car.

Objective: The ride qualities of the six passenger cars were evaluated in 4 subjects on the highway and uneven road. The relation between vibration with driving velocity and driving posture were also investigated separately. Background: Ride comfort plays an important role in the vehicle design. Vibration is the one of the principal components associated with ride comfort. Method: The acceleration of the foot, hip and back were measured using B&K accelerometers in this study. The velocity of the passenger cars was maintained at a constant speed of 80km/h on the highway and 40km/h on the uneven road. For evaluating the effects of driving velocity and driving posture on vehicle's vibration level, separate experiments were performed on the highway with 5 different vehicle speeds and 5 different backrest angles, respectively. Results: The overall ride value of the luxury car showed the best result while the smaller car showed the worst value on the highway. On the uneven road the overall ride value level was increased 75~98%. All the vehicles had the SEAT value less than 1. Faster the velocity lowers the SEAT value. The ride quality in terms of vibration gets worst when the backrest angle increased. Conclusion: The smaller car had a first mode at the higher frequency and showed higher vibration level. SEAT value was mostly affected by the seat property not by vehicle. We ranked the luxury car seat had a best vibration reduction quality than others based on SEAT values. When the driving velocity increased, the overall ride values were increased proportionally and the SEAT values were somewhat decreased. Application: Evaluation of whole-body vibration in the passenger car.

Objective: This article aims to report the results of ergonomic evaluation of some university laboratories. Background: Laboratory researchers are at risk for musculoskeletal injuries during routine laboratory procedures. However, little attention has paid to the working conditions of laboratory researchers, especially in Korea. Method: A checklist and questionnaire was developed and used to analyze the work conditions of 27 laboratories of chemistry, biology and pharmacy. Results: It was found that glove box, clean bench, and computer workstation are better than microscopy, and fume hood tasks, from ergonomic point of view. Conclusion: No domestic guideline is available for ergonomic intervention of laboratories. Further attention and studies are anticipated to improve the working conditions of laboratories.

Objective: Product design process without considering the strength of the user can cause the excessive burden on musculoskeletal system of human body. Since the muscle strength will vary depending on the body posture, the design of product should consider the characteristics of body posture. This study was performed to investigate the effects of forearm postures on the push and pull strength. Background: Overexerted force has been identified to cause musculoskeletal disorders. It is important to know the push and pull strength exerted by human when designing so that exerted force does not exceed the safety limits. Method: Maximum isometric push and pull strength of left, right and both hands were measured according to forearm postures with pronation, neutral and supination. For the study, 66 male and 30 female undergraduate students were participated as subjects. All subjects were normal and healthy with no clinical history. Results: The results showed that the push strength of male and female were 93.3% and 85.4% of pull strength. It showed that the strength of one-hand was 72.1~81.0% of the strength of two-hands, and the strength of left hand was 93.1~95.8% of the strength of right hand. The strength of female was 62% of the one of male. It was found that the strength with pronation $90^{\circ}$ was reduced up to 20% compared to the strength with neutral posture. Conclusion: Push and pull strength of male and female were reduced when forearm was rotated extremely. Application: The results of this study will be used for the prevention of work related musculoskeletal disorders and design of industrial equipment.