• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.287-293
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• 2013

Cochlear implant (CI) is an auditory prosthesis that delivers electrical stimulation via inserted electrodes into a cochlea. To evaluate CI performance, it is important to understand how auditory nerves are responded to electrical stimulations. In clinic, electrically evoked compound action potential (ECAP) is measured. In this study, we developed 3D finite element (FE) cochlear model to simulate ECAP in response to electrical stimulation. The model prododuced ECAP similar to that measured in animal experiments and clinics. This 3D FE cochlear model could be used in electrical stimulus method study to improve CI by analyzing neural responses to electrical stimulations.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.261-269
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• 2013

In this paper, the evoked potential(EP) was represented by additive delay model to comply with the variational noisy response of stimulus-event synchronization. The hybrid method of delay compensated-Wiener filtered-ensemble averaging(DWEA) was proposed to enhance the EP signal distortion occurred during averaging procedure due to synchronization timing mismatch. The performance of DWEA has been tested by surrogated simulation, which is composed of synthesized arbitrary delay and arbitrary level of added noise. The performance of DWEA is better than those of Wiener filtered-ensemble averaging and of conventional ensemble averaging. DWEA is endurable up to added noise gain of 7 for 10 % mean square error limit. Throughout the experimentation observation, it has been demonstrated that DWEA can be applied to enhance the evoked potential having the synchronization mismatch with added noise.

• Journal of KIISE
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• v.44 no.11
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• pp.1149-1155
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• 2017

Recently, with the development of communication technology, it has become possible to collect various sensor data that indicate the environmental stimuli within a space. In this paper, we propose a group emotion prediction system using a modular Bayesian network that was designed considering the psychological impact of environmental stimuli. A Bayesian network can compensate for the uncertain and incomplete characteristics of the sensor data by the probabilistic consideration of the evidence for reasoning. Also, modularizing the Bayesian network has enabled flexible response and efficient reasoning of environmental stimulus fluctuations within the space. To verify the performance of the system, we predict public emotion based on the brightness, volume, temperature, humidity, color temperature, sound, smell, and group emotion data collected in a kindergarten. Experimental results show that the accuracy of the proposed method is 85% greater than that of other classification methods. Using quantitative and qualitative analyses, we explore the possibilities and limitations of probabilistic methodology for predicting group emotion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.449-455
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• 2004

This paper presents a novel defect detection method for one chip RF front end with fault detection circuits using input matching measurement. We present a BIST circuit using 40.25{\mu}m$ CMOS technology. We monitor the input transient voltage of the RF front end to differentiate faulty and fault-free RF front end. Catastrophic as well as parametric variation fault models are used to simulate the faulty response of the RF front end. This technique has several advantages with respect to the standard approach based on current test stimulus and frequency domain measurement. Because DUT and fault detection circuits are implemented in the same chip, this test technique only requires use of digital voltmeter (RMS meter) and RF voltage source generator for simpleand inexpensive testing.

• Journal of Korean Physical Therapy Science
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• v.30 no.3
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• pp.1-13
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• 2023

Background: The bridge exercise prevents repeated damage to the tissues around the spine by reducing stimulus transmission to the ligaments and joint capsules, thereby alleviating back pain. It also contributes to strengthening the muscles of the lower extremities. Design: A Single Subject experience design. Methods: This study was conducted on 28 healthy adults in their 20s to 30s and conducted at St. Mary's Hospital in C City from May to July 2021. Four types of bridge exercise were performed in this study: the normal bridge exercise and bridge exercises with 0.5%, 1%, or 1.5% body weight resistance applied on the pelvis through manual resistance during the bridge exercise and to determine the effect of resistance applied in the bridge exercise on the activation of the trunk and lower extremities muscles. Results:This study showed that the muscle activity of the trunk and lower extremities improved significantly in response to stronger resistance when manual resistance equivalent to 0.5%, 1%, or 1.5% of body weight was applied during the bridge exercise compared to when the normal bridge exercise was performed. Conclusion: This study shows that manual resistance can be applied as an effective method of bridge exercise since muscle activity in the trunk and lower extremities increases when manual resistance causing isometric contraction is applied.

• Korean Journal of Cognitive Science
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• v.27 no.1
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• pp.1-25
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• 2016

The present study investigated the effect size of attention and consciousness on change detection. We confirmed the effect size of consciousness by comparing the condition which combined attention and consciousness and the condition of attention without consciousness. Then, we confirmed the effect size of attention by comparing the condition of attention without consciousness and the control condition which excluded attention and consciousness. For this purpose, change detection task and continuous flash suppression (CFS) were used. CFS renders a highly visible image invisible. In CFS, one eye is presented with a static stimulus, while the other eye is presented with a series of rapidly changing stimuli, such as mondrian patterns. The result is that the static stimulus becomes suppressed from conscious awareness by the stimuli presented in the other eye. We used a customized device with smartphone and google cardboard instead of stereoscope to trigger CFS. In Experiment 1-1, we reenacted some study to validate our experimental setup. Our experimental setup produced the duration of stimulus suppression that were similar to those of preceding research. In Experiment 1-2, we reenacted a study for attention without consciousness using an customized device. The results showed that attention without consciousness more strongly work as a cue. We think that it is reasonable to use CFS treatment employing smartphone and google cardboard for a follow-up study. In Experiment 2, when performing the change detection task, we measured the effect size of consciousness and attention by manipulating the consciousness level of cue. We used the method in which everything but the variable of interest kept being fixed. That way, the difference this independent variable makes to the action of the entire system can be isolated. We found that there was significant difference of correct response rate on change detection performance among different consciousness level of cue. In this study, we investigated that not only the role of attention and consciousness were different also we were able to estimated the effect size.

• Journal of Music and Human Behavior
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• v.1 no.1
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• pp.33-46
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• 2004

Mentally disable children feel as failure because they have difficulty in restricted and undifferentiated communications with others. It also makes the counter-partner feel frustrated. Therefore, in the aspects of language acquirement and communication activities, it is essential to let the disable children learn and communicate voluntarily. Music provides the unthreatening and interesting stimulus as non-language communication vehicle. Musical experiences for mentally disable children's are multi-stimulating experiences that make a positive influence in speech and language development and development of variety of talents. There are many communication intervention and method to treat the mentally disable children. One of the most effective treatments for mentally disable children to acquire communication techniques by expressing the language more naturally and joyfully is the musical therapy. This study analyzes children's communication technique referring to response action and attempt action through video tape observation. Also, this study measured the receptive and expressive language by PRES(Preschool Receptive-Expressive Language Scale) as a test tool in order to examine the pre-post language ability for respective children as pre-post period of therapy activity. First result of this study showed that music therapy with song was effective for mentally disable children in enhancing the communication techniques centered with communication response and in attempt action by increasing the communication action incidence. Secondly, pre-post comparison test with PRES showed that the music therapy with song was effective on improvement the receptive and expressive language ability of 4 children.

• The Korean Journal of Physiology
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• v.17 no.2
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• pp.93-101
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• 1983

A possibility whether the appearance of adaptation to cold climate during winter could occur or not in Taegu area was evaluated by comparing the data obtained in winter with that obtained by the same method in summer. Circulatory response was induced by the immersion of one hand in the cold water. The systemic and local responses in the blood circulation from the immersed hand and the unimmersed opposite hand were observed simultaneously. In addition Galvanic skin resistance(GSR) that is influenced by the activity of autonomic nervous system and the vascular tonicity was recorded. The experiment was performed by examining sixty healthy college students in winter and fifty in summer, whose mean age was 21.0, mean weight $60.6{\pm}0.90\;kg(male)$ and $48.3{\pm}0.98\;kg(female)$. The cold stimulus was applied by immersing the left hand into the cold water of $5^{\circ}C$ for 3 minutes, and the response was observed on immersed left hand and unimmersed right hand simultaneously. The observation was made through determining mean blood pressure, heart rate, amplitude of photoelectric capillary pulse (APCP) and GSR. The results obtained are as follows: The mean blood pressure was elevated during the cold stimulation. The increase of blood pressure in summer was more remarkable than in winter. At the recovery period the blood pressure was decreased to the control level in winter but the decrease below the control level was observed in summer. The increase of heart rate in summer was more remarkable than in winter during the cold stimulation. At the recovery period heart rate in both winter and summer was decreased below the control level. During the cold stimulation the APCP was decreased on both hands in winter. However it was more prominent on left hand indicating additional direct cold effect on immersed hand. In summer, the decrease of APCP during immersion was less remarkable than that in winter, but the regain of APCP was faster than that in winter at the recovery period. And the prompt increase of APCP over the control level has been obtained at the 3 minutes of the recovery period. The GSR was remarkably increased on immersed hand but slightly decreased on unimmersed opposite hand during the cold stimulation. Thus the finding on immersed hand indicates that the local direct effect of cold water is more prominent than the systemic effect, where as the finding on unimmersed hand indicates that the circulatory response to painful stress elicited by the cold stimulation is more prominent than cold temperature itself. In summary, it seems that the systemic circulatory response to the local cold stimulation of the one hand is arised more from the secondary elicited pain sensation and less from the low water temperature. On the contrary to the report of Kim et $al^{39)}$, the adaptation phenomena in blood pressure to the relatively mild cold climate in winter was not observed in this study. The difference of circulatory response observed in this study between winter and summer may be due to the difference of the magnitude of subjective sensation of the cold water stimulation by the seasonal changes in air temperature.

• Progress in Medical Physics
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• v.19 no.1
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• pp.73-79
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• 2008

Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa (RP) or age related macular degeneration (AMD). Recently Korean consortium launched for developing retinal prosthesis. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we performed voltage stimulation experiment both in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: $50k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. Mono-polar electrical stimulation was applied through one of the 60 MEA channel, and the remaining channels were used for recording. The electrical stimulus was a constant voltage, charge-balanced biphasic, anodic-first square wave pulse without interphase delay, and 50 trains of pulse was applied with a period of 2 sec. Different electrical stimuli were applied. First, pulse amplitude was varied (voltage: $0.5{\sim}3.0V$). Second, pulse duration was varied $(100{\sim}1,200{\mu}s)$. Evoked responses were analyzed by PSTH from averaged data with 50 trials. Charge density was calculated with Ohm's and Coulomb's law. In normal retina, by varying the pulse amplitude from 0.5 to 3V with fixed duration of $500{\mu}s$, the threshold level for reliable ganglion cell response was found at 1.5V. The calculated threshold of charge density was $2.123mC/cm^2$. By varying the pulse duration from 100 to $1,200{\mu}s$ with fixed amplitude of 2V, the threshold level was found at $300{\mu}s$. The calculated threhold of charge density was $1.698mC/cm^2$. Even after the block of ON-pathway with L-(1)-2-amino-4-phosphonobutyric acid (APB), electrical stimulus evoked ganglion cell activities. In this APB-induced degenerate retina, by varying the pulse duration from 100 to $1200{\mu}s$ with fixed voltage of 2 V, the threshold level was found at $300{\mu}s$, which is the same with normal retina. More experiment with APB-induced degenerate retina is needed to make a clear comparison of threshold of charge density between normal and degenerate retina.

• Journal of the Ergonomics Society of Korea
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• v.33 no.1
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• pp.39-48
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• 2014

Objective: This entire study has two parts. Study I aimed to develop a psychological assessment scale and the study II aimed to investigate the effects of LFN (low frequency noise) on the psychological responses in humans, using the scale developed in the study I. Background: LFN is known to have a negative impact on the functioning of humans. The negative impact of LFN can be categorized into two major areas of functioning of humans, physiological and psychological areas of functioning. The physiological impact can cause abnormalities in threshold, balancing and/or vestibular system, cardiovascular system and, hormone changes. Psychological functioning includes cognition, communication, mental health, and annoyance. Method: 182 college students participated in the study I in development of a psychological assessment scale and 42 paid volunteers participated in the study II to measure psychological responses. The LFN stimuli consisted of 12 different pure tones and 12 different 1 octave-band white noises and each stimulus had 4 different frequencies and 3 different sounds pressure levels. Results: We developed the psychological assessment scale consisting of 17 items with 3 dimensions of psychological responses (i.e., perceived physical, perceived physiological, and emotional responses). The main findings of LFN on the responses were as follows: 1. Perceived psychological responses showed a linear relation with SPL (sound pressure level), that is the higher the SPL is, the higher the negative psychological responses were. 2. Psychological responses showed quadric relations with SPL in general. 3. More negative responses at 31.5Hz LFN than those of 63 and 125Hz were reported, which is deemed to be caused by perceived vibration by 31.5Hz. 'Perceived vibration' at 31.5Hz than those of other frequencies of LFN is deemed to have amplified the negative psychological response. Consequently there found different effects of low frequency noise with different frequencies and intensity (SPL) on multiple psychological responses. Conclusion: Three dimensions of psychological responses drawn in regard to this study differed from others in the frequencies and SLP of LFN. Negative psychological responses are deemed to be differently affected by the frequency, SPL of the LFN and 'feel vibration' induced by the LFN. Application: The psychological scale from our study can be applied in quantitative psychological measurement of LFN at home or industrial environment. In addition, it can also help design systems to block LFN to provide optimal conditions if used the study outcome, .i.e., the relations between physical and psychological responses of LFN.