• The Journal of Korea Robotics Society
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• v.8 no.3
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• pp.150-155
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• 2013

Vibrotactile actuators for small consumer electronic products, such as mobile devices, have been widely used for conveying haptic sensation to users. One of the most important things in vibrotactile actuators is to be developed in the form of thin actuator which can be easily embedded into mobile devices and to provide vibrotactile signals with wide frequency band to users. Thus, this paper proposes a thin film type haptic actuator with an aim to convey vibrotactile information with high frequency bandwidth to users in mobile devices. To this end, a vibrotactile actuator which creates haptic sensation is designed and constructed based on cellulose acetate material. A cellulose acetate material charged with an electric potential can generate vibration under the AC voltage input. It is found that the motion of the actuator can have concave or convex shape by controlling a polarity of both charged membranes and the actuator performance can be modulated by increasing level of biased electric potential. The experiment clearly shows that the proposed actuator creates enough output force to stimulate human skin with a large frequency bandwidth and to simulate various vibrotactile sensations to users.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.337-341
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• 2008

This paper presents a vibrotactile space mouse which use pin-type vibrotactile display modules and a gyroscope chip. This mouse is a new interface device which is not only an input device as an ordinary space mouse but also a tactile output device. It consists of a space mouse which use gyroscope chip and vibrotactile display modules which have been developed in our own laboratory. Lately, by development of vibrotactile display modules which have small size and consume low power, vibrotactile displays are available in small sized embedded systems such as wireless mouses or mobile devices. Also, development of new sensors like miniature size gyroscope by MEMS technology enables manufacturing of a small space mouse which can be used in the air not in a plane. The vibrotactile space mouse proposed in this paper recognizes motion of a hand using the gyroscope chip and transmits the data to PC through Bluetooth. PC application receives the data and moves pointer. Also, 2 by 3 arrays of pin-type vibrotactile actuators are mounted on the front side of the mouse where fingers of a user's hand contact, and those actuators could be used to represent various information such as gray-scale of an image or Braille patterns for visually impared persons.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.8
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• pp.795-800
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• 2014

In this paper, a vibrotactile pad system, T-mobile, is developed to provide vibrotactile cues for hand-held devices. A grooved and slim design is adapted to the back-side plane of the T-mobile, and the contact part consists of 12 vibrotactile panels which can operate independently and separately. To be isolated among vibrotactile actuators, the surface of the cover is divided into several pieces. Each vibrating module consists of a linear resonant actuator, a section of covering surface, and a vibration isolator. In order to provide spatial and directional information, sensory saltation and phantom sensation are applied to the T-mobile. To evaluate the developed device, two experiments were conducted to test whether directional information and spatial information can be successfully displayed by the device. Additionally, in order to find optimal stimulation by sensory saltation, an empirical test was conducted. As a result, spatial and directional information would be useful for displaying intuitive information for hand-held devices with vibrotactile feedback and reasonable near-optimal value for sensory saltation was obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.397-398
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• 2011

• Journal of the Ergonomics Society of Korea
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• v.18 no.3
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• pp.1-12
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• 1999

This study investigated human operator's perceptual and psychophysical responses to vibrotactile stimulation on various parts of the hand. Using a small vibrotactile display, the effects of three mechanical parameters consisting vibrotactile stimulations, i.e., vibration frequency, pulse-width modulation duty cycle, and number of contactors, on differential thresholds were examined at five different loci of the hand. It was observed that differential threshold varies with vibration frequency and number of active contactors. Differential sensitivity was the greatest at the vibration frequency of 120 Hz. The differential sensitivity was not found to be affected by loci on the hand. The area of stimulation on the hand was also found to be significant in that the sensitivity increased with the number of active contactors. It should be noted that the conclusions from this study generally correspond to those from the previous study on the absolute sensitivity. which means that tactile sensitivity to vibrotactile stimulations can be controlled with a systematic and consistent passion for emulating normal everyday contact on human hands in teleoperation and virtual reality applications.

• Journal of Information Processing Systems
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• v.14 no.5
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• pp.1102-1113
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• 2018

Vibrotactile feedback is widely used in designing non-visual interactions on mobile phones, such as message notification, non-visual reading, and blind use. In this work, novel vibrotactile codes are presented to implement a non-visual text reading system for mobile phones. The 26 letters of the English alphabet are formed in an index table with four rows and seven columns, and each letter is mapped using the codes of vibrations. Two kinds of vibrotactile codes are designed with the actuator's on and off states and with specific lengths (short and long) assigned to each state. To improve the efficiency of tactile perception and user satisfaction, three user experiments are conducted. The first experiment explores the maximum number of continuous vibrations and minimum vibration time of the actuator's on and off states that the human can perceive. The second experiment determines the minimum interval between continuous vibrations. The vibrotactile reading system is designed and evaluated in the third experiment according to the results of the two preceding experiments. Results show that the character reading accuracy reaches 91.7% and the character reading speed is approximately 617.8 ms. Our method has better reading efficiency and is easier to learn than the traditional Braille coding method.

• Smart Media Journal
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• v.1 no.4
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• pp.8-17
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• 2012

In this paper, we introduce the appoaches that aim to improve user experience in mobile device by the use of multiple vibration signal feedback, conducted by Haptics and Virtual Reality laboratory at POSTECH. We introduce current progresses of our 'Vibrotactile flow using multiple vibration actuators' and 'Real-time dual-channel haptic music player.' The 'Vibrotactile flow using multiple vibration actuators' produces vibrotactile flow sensations by using multiple actuators and that improves the information transfer on mobile devices. The 'Real-time dual-channel haptic music player' generates vibrotactile sensation by transforming auditory signal, which improves the user experience of mobile devices. These approaches can be good examples to fulfill the demands of better information transfer capability and user experience on mobile devices.

• Journal of the Ergonomics Society of Korea
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• v.17 no.2
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• pp.1-10
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• 1998

The objective of this study is to investigate hwnan operator's perceptual and psychophysical responses to vibrotactile stimulation on various parts of the hand. Using a small vibrotactile display, five different loci of the hand along with two other mechanical parameters consisting vibrotactile stimulations, which are vibration frequency and number of active contactors, were examined for the effects on absolute thresholds. All test variables were found to have significant effects on thresholds. It was observed that absolute threshold is a function of vibration frequency and number of active contactors. Tactile sensitivity was the greatest at the vibration frequency of 240 Hz, and the fingertip was found to be the most sensitive locus on the hand. The area of stimulation on the hand was also found to be significant in that the sensitivity increased with the number of active contactors. The results of the study generally supported those of other previous studies. It should also be noted, however, that the conclusions from the study should be limited to the absolute sensitivity, not to the suprathreshold intensities of normal everyday contact with the hands.

• Journal of the HCI Society of Korea
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• v.1 no.1
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• pp.29-36
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• 2006

Tactile displays can provide useful information without disturbing others and are particularly useful for people with visual or auditory impairments. They can also complement other displays. In this paper, we present a new vibrotactile display device for wearable, mobile, and ubiquitous computing environments. The proposed vibrotactile device has a $5{\times}5$ array configuration for displaying complex information such as letters, numbers, and haptic patterns as well as simple directional ques and situation awareness alarms. Commercially available coin-type vibration motors are embedded vertically in flexible mounting pads in order to best localize vibrations on the skin. An embedded microprocessor controls the motors sequentially with an advanced tracing mode to increase recognition rate. User studies with the vibrotactile device on the top of the foot show 86.7% recognition rate for alphabet characters after some training. In addition, applying vibrotactile device to driving situation shows 83.9% recognition rate. We also propose some potentially useful application scenarios including Caller Identification for mobile phones and Navigation Aids for GPS systems while driving.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.41-48
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• 2021

Purpose : The purpose of this study is to find out if it helps to improve static balance ability and weight bearing rate for chronic stroke patients with poor balance in clinical intervention through a method of correcting movement errors while performing a task by vibrotactile bio-feedback providing pressure information. Methods : Fifteen chronic stroke patients (12 male and 3 female) were participated in this study. To examine the effects of vibrotactile bio-feedback and general standing without bio-feedback on static balance ability and weight distribution symmetric index in all subjects randomized with R Studio. The static balance ability and weight distribution symmetric index of the participants was evaluated using a force plate. A paired t-test was used for comparison of each conditions. Statistical significance was set at α=0.05. Results : The comparisons of static balance ability and weight distribution symmetric index in chronic stroke patients after two different condition are as follows. In the static balance ability and weight distribution symmetric index, the vibrotactile feedback providing pressure information showed a significant difference compared to none feedback (p<.001). Conclusion : The vibrotactile bio-feedback providing pressure information in real time can support an improve in static balance ability, uniform weight bearing rehabilitation in chronic stroke patients. In the future, it is hoped that a follow-up study that provides a better direction of intervention compared to various feedback interventions commonly used in clinical practice.