• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.11a
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• pp.103-109
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• 2002

본 연구에서는 가상현실사용자들이 모션베이스를 사용함에 따라 가상현실에 대한 평가가 어떻게 달라지는지를 조사하였다. 33명의 피험자를 대상으로 모션베이스 평가설문과 자기보고를 통해 가상현실에서의 현실감, 재미, 멀미감을 조사하고 가상주행 전, 중, 후에 내장근전위, 피부전도도, 말초체온, 말초혈류량, 심박률, 눈 깜박임의 생리신호를 측정, 분석함으로써 모션베이스 유무에 따른 심리·생리적인 변수들에서의 차이를 알아보았다. 모든 피험자는 2주 간격으로 모션베이스 사용조건과 모션베이스를 사용하지 않는 조건에서 두 번 가상현실을 경험하였다. 가상현실에 대한 현실감, 재미항목에서 모두 모션베이스를 사용한 조건이 높은 점수를 나타냈다. 또한 모션베이스를 사용한 조건에서 멀미보고수가 감소하는 경향이 나타났다. Tachyarrythmia의 상대파워 변화량과 PPG 최대진폭의 평균변화량 비교는 모션베이스를 사용한 가상현실 조건이 생리적인 요동을 적게 일으키는 것으로 나타났다. 이러한 결과들은 시각제시기와 동기화된 모션베이스를 도입함으로써, 가상현실에 대한 현실감은 높이면서 멀미감은 줄일 수 있다는 가능성을 보여준다.

• The Journal of the Korea Contents Association
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• v.20 no.6
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• pp.439-444
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• 2020

The purpose of this study is to seek an alternative method to prevent the contamination of normal saline caused by the back-flow of Gadolinium Based Contrast Agent(GBCA) by the use of auto-injector for dynamic MRI. The research method is to manufacture the non-return valve as an alternative to the existing, and to examine the usefulness of the normal saline by dividing the state of normal saline into three groups. The signal intensity were compared. As a result, there was no statistically significant difference between normal saline before injection of group 1 and group 3 non-return valve (p> 0.05). It is analyzed that the self-produced non-return valve completely blocked the GBCA back to normal saline when the GBCA was injected. In conclusion, the application of the non-return valve presented in this study for dynamic MRI imaging using the auto injector can prevent normal saline contamination due to GBCA back-flow.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.383-388
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• 1994

Chaotic analysis of EEG signal responding to auditory stimulus with various carrier frequency and constant triggering frequency is given in this paper. The EEG signal is obtained from the digital 12channel EEG system made in our laboratory. The carrier frequency is varied from 1 kHz to 3 kHz by 0.5 kHz step. Chaos analysis such as pseudo phase space portrait, Lyapunov exponent, and so on is done on the auditory stimulated evoked potential. This result is found to be quite consistent with the well known results from the psychological perception theory.

• Science of Emotion and Sensibility
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• v.23 no.3
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• pp.3-10
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• 2020

This study is aimed at investigating drivers' reactions to yellow signal dilemma situations as a result of the existing signal system, and developing a new signal system. A driver-centered coping model was developed through bio-signal analysis. The driver's physiological response in the existing signal system was observed, and the signal system was developed by applying intersection road driving conditions using a car graphic simulator. Participants were classified into a control group (existing signal system) and an experimental group for a new yellow signal system (new signal system). Based on the results, the emergence of parasympathetic nerves was higher in the experimental group than in the control group, where a statistically significant difference was observed (p < 0.05). The newly developed signal system appeared to cause tension among drivers; however, the sympathetic to parasympathetic nerve ratio was 6: 4, which could be interpreted as an ideal balance. We conclude that drivers can drive more stably if the coping signal system developed in this study is applied to the traffic system.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.23-33
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• 2023

Sucrose (suc) is a disaccharide that consists of glucose (glu) and fructose (fru). It is a carbohydrate source that acts as a nutrient molecule and a molecular signal that regulates gene expression and alters metabolites. This study aimed to evaluate whether suc-specific signaling induces an increase in bioactive compounds by exogenous suc absorption via roots or whether other factors, such as osmotic stress or biotic stress, are involved. To compare the osmotic stress induced by suc treatment, 4-week-old cultured mugwort plants were subjected to Hoagland nutrient solution with 10 mM, 30 mM, and 50 mM of suc or mannitol (man) for 3 days. Shoot fresh weight in suc and man treatments was not significantly different from the control. Both man and suc treatments increased the content of bioactive compounds in mugwort, but they displayed different enhancement patterns compared to the suc treatments. Mugwort extract treated with suc 50 mM effectively protected HepG2 liver cells damaged by ethanol and t-BHP. To compare the biotic stress induced by suc treatment, 3-week-old mugwort plants were subjected to microorganism and/or suc 30 mM with Hoagland nutrient solution. Microorganisms and/or suc 30 mM treatments showed no difference about the shoot fresh weight. However, sugar content in mugwort treated with suc 30 mM and microorganism with suc 30 mM treatment was significantly higher than that of the control. Suc 30 mM and microorganism with suc 30 mM were effective in enhancing bioactive compounds than microorganism treatment. These results suggest that mugwort plants can absorb exogenous suc via roots and the enhancement of bioactive compounds by suc treatment may result not from osmotic stress or biotic stress because of microorganism, but by suc-specific signaling.

• Korean Journal of Cognitive Science
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• v.21 no.2
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• pp.309-338
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• 2010

In this paper, we studied the brain-computer interface (BCI). BCIs help severely disabled people to control external devices by analyzing their brain signals evoked from motor imageries. The findings in the field of neurophysiology revealed that the power of $\beta$(14-26 Hz) and $\mu$(8-12 Hz) rhythms decreases or increases in synchrony of the underlying neuronal populations in the sensorymotor cortex when people imagine the movement of their body parts. These are called Event-Related Desynchronization / Synchronization (ERD/ERS), respectively. We implemented a BCI-based mouse interface system which enabled subjects to control a computer mouse cursor into four different directions (e.g., up, down, left, and right) by analyzing brain signal patterns online. Tongue, foot, left-hand, and right-hand motor imageries were utilized to stimulate a human brain. We used a non-invasive EEG which records brain's spontaneous electrical activity over a short period of time by placing electrodes on the scalp. Because of the nature of the EEG signals, i.e., low amplitude and vulnerability to artifacts and noise, it is hard to analyze and classify brain signals measured by EEG directly. In order to overcome these obstacles, we applied statistical machine-learning techniques. We could achieve high performance in the classification of four motor imageries by employing Common Spatial Pattern (CSP) and Linear Discriminant Analysis (LDA) which transformed input EEG signals into a new coordinate system making the variances among different motor imagery signals maximized for easy classification. From the inspection of the topographies of the results, we could also confirm ERD/ERS appeared at different brain areas for different motor imageries showing the correspondence with the anatomical and neurophysiological knowledge.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.72-73
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• 2007

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2011.11a
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• pp.21-22
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.989-990
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• 2010

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.229-235
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• 2013

In this paper, we investigate several important issues on the implementation of a totally implantable microsystem for brain-machine interface that has been attracting a lot of attention recently. So far most of the scientific research has been focused on the high performance, low power electronics or systems such as neural signal amplifiers and wireless signal transmitters, but the real application of the implantable microsystem is affected significantly by a number of factors, ranging from design of the encapsulation structure to physiological and anatomical characteristics of the brain. In this work, we discuss on the thermal effect of the system, the detecting volume of the neural probes, wireless data transmission and power delivery, and physiological and anatomical factors that are critically important for the actual implementation of a totally brain implantable neural interface microsystem.