Soon-Cheol Chung

Effects of age, gender, and weight on the cerebellar volume of Korean people

The average cerebellar volume of Korean men (135.19 cm3) is larger than that of Korean women (123.06 cm3), and that of subjects in their twenties (134.28 cm3) is larger than that of subjects in their forties (121.83 cm3). Atrophy of the cerebellum is more markedly observed in men than in women. There is a relation between body weight and cerebellar volume for men, but not for women.

The effect of 30% oxygen on visuospatial performance and brain activation: An fMRI study

This study aimed to investigate the hypothesis that administration of the air with 30% oxygen compared with normal air (21% oxygen) enhances cognitive functioning through increased activation in the brain. A visuospatial task was presented while brain images were scanned by a 3 T fMRI system. The results showed that there was an improvement in performance and also increased activation in several brain areas in the higher oxygen condition. These results suggest that a higher concentration of breathed oxygen increases saturation of blood oxygen in the brain and facilitates performance.

Effects of gender, age, and body parameters on the ventricular volume of Korean people

The purpose of this study was to measure the average ventricular volume of normal Koreans (aged in their 20s or 40s) and to analyze the effects of gender, age, and body parameters, such as height and weight on ventricle size. Magnetic resonance brain images were recorded for 118 people in their 20s (58 men, 60 women) and 100 in their 40s (41 men, 59 women). Using automatic and manual segmentation techniques, the volumes of the lateral and the third and fourth ventricles were calculated. To investigate the different and interactive effects of gender and age on ventricular volume, two-way analysis of variance (ANOVA) with gender and age as independent variables was carried out. Multiple regression analysis was used to investigate the effect of body parameters, such as height and weight according to gender on changes in ventricular volume. The average ventricular volume for people in their 20s was 16.2 cm3, and that for people in their 40s was 24.9 cm3. The average ventricular volume for men and women was 22.9 and 18.1 cm3, respectively. The average ventricular volume for men was greater than that for women, and that for people in their 40s was greater than that in their 20s. Enlargement of the ventricles on aging was more markedly observed in men than in women. There was a positive relationship between the body height and ventricular volume for men but not for women. There was no relationship between weight and ventricular volume for either men or women.

Laser-induced thermoelastic effects can evoke tactile sensations

Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (< ~2.5 °C) in temperature at the surface of the skin, examined by both thermal camera and the Monte Carlo simulation, indicate that laser does not evoke heat-induced nociceptive sensation. In the human EEG study, brain responses to both mechanical and laser stimulation are consistent, along with subjective reports of the non-nociceptive sensation of laser stimuli.

Mid-air tactile stimulation using laser-induced thermoelastic effects: The first study for indirect radiation

This paper reports our recent finding that a laser that is radiated on a thin light-absorbing elastic medium attached on the skin can elicit a tactile sensation of mechanical tap. Laser radiation to the elastic medium creates inner elastic waves on the basis of thermoelastic effects, which subsequently move the medium and stimulate the skin. We characterize the associated stimulus by measuring its physical properties. In addition, the perceptual identity of the stimulus is confirmed by comparing it to mechanical and electrical stimuli by means of perceptual spaces. All evidence claims that indirect laser radiation conveys a sensation of short mechanical tap with little individual difference. To the best of our knowledge, this is the first study that discovers the possibility of using indirect laser radiation for mid-air tactile rendering.

Changes in memory performance, heart rate, and blood oxygen saturation due to 30% oxygen administration.

This study investigated the effect of 30% oxygen administration on memory cognitive performance, blood oxygen saturation, and heart rate. Ten healthy male and female college students (male: 25.8 ± 0.8 years, female: 24.2 ± 1.9 years) participated in the study. The results of the memory performance analysis reveal that word recall rates were enhanced with 30% oxygen administration compared to 21% oxygen. When 30% oxygen was supplied, blood oxygen saturation was increased and heart rate was decreased compared to that with 21% oxygen administration. Significant positive correlations were found between changes in oxygen saturation and heart rate and memory performance. This result supports the hypothesis that 30% oxygen administration would lead to increases in memory performance.

Effects of high concentration oxygen administration on n-back task performance and physiological signals

This study investigated the effect of 40% oxygen administration on n-back task performance, blood oxygen saturation and heart rate. Five male (25.8 +/- 1.3 years) and five female (23.0 +/- 1.0 years) college students were selected as the subjects for this study. The experiment consisted of two runs: one was an n-back task with normal air (21% oxygen) administered and the other was with hyperoxic air (40% oxygen) administered. The experimental sequence in each run consisted of Rest1 (1 min), 0-back task (1 min), 2-back task (2 min) and Rest2 (4 min). Blood oxygen saturation and heart rate were measured throughout the four phases. The results of the n-back behavioural analysis reveal that accuracy rates were enhanced with 40% oxygen administration compared to 21% oxygen. When 40% oxygen was supplied, blood oxygen saturation was increased and heart rate was decreased compared to that with 21% oxygen administration. It is suggested that 40% oxygen can stimulate brain activation by increasing actual blood oxygen concentration in the process of cognitive performance, and hyperoxia makes heart rate decrease. This result supports the hypothesis that 40% oxygen administration would lead to increases in n-back task performance.

A study on the effects of 40% oxygen on addition task performance in three levels of difficulty and physiological signals.

This study investigated the effect of 40% oxygen administration on addition task performance in three levels of difficulty and physiological signals, such as blood oxygen saturation and heart rate. The accuracy rates of the addition tasks were enhanced with 40% oxygen administration compared to 21% oxygen. As the difficulty level increased, the difference in the accuracy rate between 40% and 21% oxygen administration increased. When 40% concentration oxygen was supplied, blood oxygen saturation was increased and heart rate was decreased compared to that with 21% oxygen administration. A positive correlation was found between task performance and oxygen saturation level during the Task3 phase. This result suggests that 40% oxygen administration would lead to increases in addition task performance.

Measurements and Characterization of Cerenkov Light in Fiber-Optic Radiation Sensor Irradiated by High-Energy Electron Beam

In general, Cerenkov light can cause a problem in detecting a real light signal that is generated in a fiber-optic radiation sensor using an organic scintillator for dose measurements of high-energy electron beams. In this study, the intensity of Cerenkov light is measured and characterized as functions of incident angles, energy, and field size of the electron beam from a LINAC (linear accelerator). To remove or minimize Cerenkov light, a subtraction method using a background optical fiber is investigated.

The effect of highly concentrated oxygen administration on cerebral activation levels and lateralization in visuospatial tasks.

This study investigated what effect a 30% oxygen administration had on visuospatial cognitive performance and cerebral activation and lateralization using fMRI. Eight college students were selected as the subjects for this study. An oxygen dispenser that provided 21% and 30% oxygen at a constant rate of 8L/min was developed. In order to measure the performance level of visuospatial cognition, two psychological tests were also developed. The experiment consisted of two runs, one for a visuospatial cognition task with normal air (21% oxygen) and the other for a visuospatial cognition task with hyperoxic air (30% oxygen). Functional brain images were taken with a 3T MRI using the single-shot EPI method. The results of the visuospatial behavioral analysis reveal that accuracy rates were enhanced with 30% oxygen administration when compared to 21% oxygen. There were more activations observed at the bilateral occipital, parietal, and frontal lobes with 30% oxygen administration. However, decreased cerebrum lateralization was observed with 30% oxygen administration in the same regions compared with 21% oxygen administration. Thus, it is concluded that the positive effect on the visuospatial cognitive performance level by the highly concentrated oxygen administration resulted from an increase of cerebrum activation and a decrease of cerebrum lateralization.