The Effect of 3D Immersive Virtual Reality on Virtual Presence and Perceived Usefulness in Machining Center Learning for Hearing Impaired Learners

( Jiheon Ryu ),( Minjeong Kim ),( Seungyeon Han ),( Insook Han ),( Jungo Yoon ),( Dongyeon Choi ),( Seungbum Ryu ) 한국교육공학회 2016 한국교육공학회 학술대회발표자료집 Vol.2016 No.1

Deaf and hard-of-hearing learners have unusual difficulty in their reasoning and abstract thinking due to hearing loss. In regard of spatial reasoning, in particular, even with enhanced visual imagery abilities, deaf and hard-of-hearing learners are not necessarily capable of conducting inductive reasoning about spatial structure. It is also reported that deaf and hard-of-hearing learners produce greatly less visual-spatial schematic representation depicting the relationship between objects than the hearing counterparts when they solve abstract cognitive task. Based on the promises of virtual reality technologies as an instructional and training tool for hearing learners`` spatial rotation, efforts have been made to develop and use 3D virtual reality games to improve the induction of spatial structure among deaf and hard-of-hearing learners. However, these studies mainly examined the effectiveness of 3D virtual training compared to 2D and did not include emerging current technologies that provide learners with hearing impairment with more engaging visual representation and enhanced interactivity. In fact, there are many developmental studies that used head mounted display for more engaging and immersive virtual experiences and more recent technological advances enable free hand interaction in touchless NUI for using gestures in 3D virtual spaces. In this respects, the purpose of this study was to develop a 3D virtual environment to improve spatial reasoning ability of hearing impaired learners in machine operating learning. We developed the 3D virtual environment with head mounted display (Oculus Rift) and touchless NUI (Leap Motion sensor). To test the usability of this system, 18 hearing impaired students who were different in the level of prerequisite learning, experience of virtual reality, and 3D immersive game participated for the usability test of 3D virtual space. The exploring of 3D immersive virtual space was divided into two sessions. In the first session, there were three steps such as information desk, watching how to use user interfaces, and studying in the tool room. And for the second session, exploring in the machine room was put into practice. Same experimental protocol was applied to all procedures of usability test. After the participants explored the 3D virtual space, an survey for virtual presence and interview were conducted with a hearing impaired students. The usability test results revealed that the 3D virtual environment with emerging technologies has a potential to help hearing impaired learners by providing realistic and immersive experiences with concrete 3D virtual objects. However, there were significant difference in the expectation and application of 3D virtual environment, depending on learners`` level of prerequisite learning and experience of 3D virtual game. For the effectiveness of learning, virtual environment was more effective on visual-related learning contents than those of text-based learning materials. The results also indicated that certain portion of specific areas that are impossible for safety reasons was appropriate for applying 3D virtual environment to. Further revision of the system is needed by considering both learners`` physical and cognitive characteristics.

Intrinsically stretchable multi-functional fiber with energy harvesting and strain sensing capability

Ryu, Jeongjae,Kim, Jaegyu,Oh, Jinwon,Lim, Seongjin,Sim, Joo Yong,Jeon, Jessie S.,No, Kwangsoo,Park, Steve,Hong, Seungbum Elsevier 2019 Nano energy Vol.55 No.-

<P><B>Abstract</B></P> <P>As future generations of wearable electronics are expected to be directly worn, fiber-based electronics are expected to become increasingly more important in the coming years, as they can be weaved into textiles to provide higher comfort, durability, and integrated multi-functionalities. Herein, we demonstrate an intrinsically stretchable multi-functional hollow fiber capable of harvesting mechanical energy and detecting strain. For energy harvesting, we have utilized a stretchable ferroelectric layer composed of P(VDF-TrFE) in a matrix of elastomer, sandwiched between stretchable electrodes composed of multi-walled carbon nanotubes and PEDOT:PSS. We have demonstrated voltage and current generation under stretching and normal pressure, with output voltage and current as high as 1.2 V and 10 nA, respectively. Furthermore, the hollow architecture enabled the harvesting of pressure coming from internal liquid flow, adding another dimension of harvesting mechanical energy. The stretchable electrodes were used as strain sensors, which exhibited high gauge factor of 80–177 in the 0–50% strain range, along with low hysteresis and durability. These features render our multi-functional fiber highly suitable for wearable electronic applications in the near future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed an intrinsically stretchable multi-functional hollow fiber. </LI> <LI> Strain can be detected with high sensitivity (gauge factor up to 177). </LI> <LI> The fiber can harvest energy coming from various external mechanical stimuli. </LI> <LI> Our fiber has potential in the field of wearable, and robotic applications. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Flexible piezoelectric liquid volume sensor

Ryu, Jeongjae,Jeong, Hanbert,Chen, Yugang,Oh, Chungik,Kim, Jaegyu,Kim, Hongjun,Cho, Seongwoo,No, Kwangsoo,Park, Yong-Hwa,Park, Steve,Hong, Seungbum Elsevier 2018 Sensors and actuators. A, Physical Vol.276 No.-

<P><B>Abstract</B></P> <P>We report a non-contact type polyvinylidene fluoride (PVDF)-based liquid volume sensor. When a liquid container vibrates due to an applied impact, our sensor that is attached to the wall of the container detects the resonance frequency of vibration, which shifts as a result of change in liquid volume. The sensitivity of our sensor was enhanced by stacking multiple sensors in series. A PVDF bimorph actuator was also fabricated to demonstrate an integrated actuator-sensor system. We believe that the results presented in this work will pave the way for novel applications in volume sensing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed a contact-free liquid volume sensor based on a flexible PVDF film. </LI> <LI> Resonance frequency of vibration is detected using our sensor when a liquid container vibrates. </LI> <LI> A simulation describes the relationship between resonance frequecy and liquid volume. </LI> <LI> Sensitivity increases with stacked multiple sensors in series. </LI> <LI> An integrated actuator-sensor system is demonstrated. </LI> </UL> </P>

Improved enantioselectivity of thermostable esterase from Archaeoglobus fulgidus toward (S)-ketoprofen ethyl ester by directed evolution and characterization of mutant esterases.

Kim, Jinyeong,Kim, Seungbum,Yoon, Sangyoung,Hong, Eunsoo,Ryu, Yeonwoo Springer International 2015 Applied microbiology and biotechnology Vol.99 No.15

<P>Thermostable esterases have potential applications in various biotechnology industries because of their resistance to high temperature and organic solvents. In a previous study, we isolated an esterase from Archaeoglobus fulgidus DSM 4304 (Est-AF), which showed high thermostability but low enantioselectivity toward (S)-ketoprofen ethyl ester. (R)-ketoprofenor (S)-ketoprofenis produced by esterase hydrolysis of the ester bond of (R,S)-ketoprofen ethyl ester and (S)-ketoprofen has better pharmaceutical activity and lower side effects than (R)-ketoprofen. Therefore, we have generated mutants of Est-AF that retained high thermostability whilst improving enantioselectivity. A library of Est-AF mutants was created by error-prone polymerase chain reaction, and mutants with improved enantioselectivity were isolated by site-saturation mutagenesis. The regions of Est-AF containing amino acid mutations were analyzed by homology modeling of its three-dimensional structure, and structure-based explanations for the changes in enantioselectivity are proposed. Finally, we isolated two mutants showing improved enantioselectivity over Est-AF (ee%?=?-16.2??0.2 and E?=?0.7??0.0): V138G (ee%?=?35.9??1.0 and E?=?3.0??0.1) and V138G/L200R (ee%?=?89.2??0.2 and E?=?19.5??0.5). We also investigated various characteristics of these mutants and found that the mutants showed similar thermostability and resistance to additives or organic solvents to Est-AF, without a significant trade-off between activity and stability.</P>

Gender Dfferences in Ground Reaction Force Components

Park, Sang-Kyoon,Koo, Seungbum,Yoon, Suk-Hoon,Park, Sangheon,Kim, Yongcheol,Ryu, Ji-Seon Korean Society of Sport Biomechanics 2018 한국운동역학회지 Vol.28 No.2

Objective: The aim of this study was to investigate gender differences in ground reaction force (GRF) components among different speeds of running. Method: Twenty men ($age=22.4{\pm}1.6years$, $mass=73.4{\pm}8.4kg$, $height=176.2{\pm}5.6cm$) and twenty women ($age=20.7{\pm}1.2years$, $mass=55.0{\pm}8.2kg$, $height=163.9{\pm}5.3cm$) participated in this study. All participants were asked to run on an instrumented dual belt treadmill (Bertec, USA) at 8, 12, and 16 km/h for 3 min, after warming up. GRF data were collected from 30 strides while they were running. Hypotheses were tested using one-way ANOVA, and level of significance was set at p-value <.05. Results: The time to passive peaks was significantly earlier in women than in men at three different running speeds (p<.05). Further, the impact loading rates were significantly greater in women than in men at three different running speeds (p<.05). Moreover, the propulsive peak at 8 km/h, which is the slowest running speed, was significantly greater in women than in men (p<.05), and the vertical impulse at 16 km/h, which is the fastest running speed, was significantly greater in men than in women (p<.05). The absolute anteroposterior impulse at 8 km/h was significantly greater in women than in men (p<.05). In addition, as the running speed increased, impact peak, active peak, impact loading rate, breaking peak, propulsive peak, and anteroposterior impulse were significantly increased, but vertical impulse was significantly decreased (p<.05). Conclusion: The impact loading rate is greater in women than in men regardless of different running speeds. Therefore, female runners might be exposed to the risk of potential injuries related to the bone and ligament. Moreover, increased running speeds could lead to higher possibility of running injuries.

Gender Dfferences in Ground Reaction Force Components

( Sang-kyoon Park ),( Seungbum Koo ),( Suk-hoon Yoon ),( Sangheon Park ),( Yongcheol Kim ),( Ji-seon Ryu ) 한국운동역학회 2018 한국운동역학회지 Vol.28 No.2

Objective: The aim of this study was to investigate gender differences in ground reaction force (GRF) components among different speeds of running. Method: Twenty men (age=22.4±1.6 years, mass=73.4±8.4 kg, height=176.2±5.6 cm) and twenty women (age=20.7±1.2 years, mass=55.0±8.2 kg, height=163.9±5.3 cm) participated in this study. All participants were asked to run on an instrumented dual belt treadmill (Bertec, USA) at 8, 12, and 16 km/h for 3 min, after warming up. GRF data were collected from 30 strides while they were running. Hypotheses were tested using one-way ANOVA, and level of significance was set at p-value <.05. Results: The time to passive peaks was significantly earlier in women than in men at three different running speeds (p<.05). Further, the impact loading rates were significantly greater in women than in men at three different running speeds (p<.05). Moreover, the propulsive peak at 8 km/h, which is the slowest running speed, was significantly greater in women than in men (p<.05), and the vertical impulse at 16 km/h, which is the fastest running speed, was significantly greater in men than in women (p<.05). The absolute anteroposterior impulse at 8 km/h was significantly greater in women than in men (p<.05). In addition, as the running speed increased, impact peak, active peak, impact loading rate, breaking peak, propulsive peak, and anteroposterior impulse were significantly increased, but vertical impulse was significantly decreased (p<.05). Conclusion: The impact loading rate is greater in women than in men regardless of different running speeds. Therefore, female runners might be exposed to the risk of potential injuries related to the bone and ligament. Moreover, increased running speeds could lead to higher possibility of running injuries.

Membrane crystallinity and fuel crossover in direct ethanol fuel cells with Nafion composite membranes containing phosphotungstic acid

Kim, Hongjun,Lee, Sunghwan,Kim, Suran,Oh, Chungik,Ryu, Jeongjae,Kim, Jaegyu,Park, Eugene,Hong, Seungbum,No, Kwangsoo Springer-Verlag 2017 JOURNAL OF MATERIALS SCIENCE - Vol.52 No.5

<P>We report on the effect of the addition of phosphotungstic acid (PWA) in Nafion membrane on ethanol-crossover and the proton conductivity for DEFC application. A set of PWA-Nafion composite membranes (PWA 0, 5, 10, 15, 20 wt%) was prepared by solution casting and their microstructures, diffraction patterns, permeability, and proton conductivity were systematically characterized. The significant reduction in ethanol-crossover is observed with increasing PWA concentration in PWA-Nafion membranes, which is mainly attributed to an improvement in crystallinity of the membrane. PWA provides additional nucleation sites during solidification leading to higher crystallinity, which is supported by the membrane permeability tests. The proton conductivity of the composites is enhanced with PWA concentration until 15 wt% due to an increase in hopping pathways, while higher PWA of 20 wt% leads to a conductivity decrease possibly due to the excessive particle aggregations that limit ion transports. These PWA-Nafion composites were implemented in prototype DEFC devices as a membrane and the maximum power density achieved was 22% higher than that of commercial Nafion-117 device.</P>

족근골 융합 절제술에 따른 후족부 운동 분석

부준요(Junyo Boo),박건우(Gunwoo Park),류현우(Hyeonwoo Ryu),장우영(Woo Young Jang),구승범(Seungbum Koo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

The talocalcaneal coalition reduces the range of motion in the subtalar joint. Resection surgery is required to improve the joints range of motion and restore physiological gait. Measuring joint kinematics is important to understand the effectiveness of surgery, but past studies had difficulties in obtaining accurate joint kinematics. In this study, the joint kinematics of hindfoot joint of talocalcaneal coalition patients were measured before and after resection using a biplane fluoroscopy imaging system. The range of motion of the hindfoot joint was statistically analyzed to find out whether surgery affects the range of motion of the joint. The range of motion of the subtalar joint had significantly increased after the resection, and the eversion/inversion motion of the tibiocalcaneal motion had significantly increased. Lack of eversion/inversion motions may increase instability in gait, and increasing the range of eversion/inversion motions in tibiocalcaneal motion affects shock absorption, contributing to increasing overall stability.

족근골 융합 절제술에 따른 후족부 운동 분석

부준요(Junyo Boo),박건우(Gunwoo Park),류현우(Hyeonwoo Ryu),장우영(Woo Young Jang),구승범(Seungbum Koo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

The talocalcaneal coalition reduces the range of motion in the subtalar joint. Resection surgery is required to improve the joints range of motion and restore physiological gait. Measuring joint kinematics is important to understand the effectiveness of surgery, but past studies had difficulties in obtaining accurate joint kinematics. In this study, the joint kinematics of hindfoot joint of talocalcaneal coalition patients were measured before and after resection using a biplane fluoroscopy imaging system. The range of motion of the hindfoot joint was statistically analyzed to find out whether surgery affects the range of motion of the joint. The range of motion of the subtalar joint had significantly increased after the resection, and the eversion/inversion motion of the tibiocalcaneal motion had significantly increased. Lack of eversion/inversion motions may increase instability in gait, and increasing the range of eversion/inversion motions in tibiocalcaneal motion affects shock absorption, contributing to increasing overall stability.