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Effects of Chair-Based Fidgeting and Age on Prefrontal Brain Activity and Cognitive Performance
Jaejin Hwang,In-Sop Kim,Charan Madasu,Chaemin Lee 한국언어치료학회 2023 言語治療硏究 Vol.32 No.1
Purpose: The objective of this study was to evaluate the effects of chair-based fidgeting and age on prefrontal brain activities and cognitive performances of neurocognitive tasks involving executive functioning and working memory. Methods: In a repeated-measures laboratory setting, 12 healthy adults (6 young and 6 older adults) were exposed to the chair-based fidgeting and the conventional sitting workstation, respectively. After the short-term exposure of each condition, participants performed five neurocognitive tasks oriented for executive functioning and working memory. Results: The hemodynamic activities via functional near- infrared spectroscopy (fNIRS) in the prefrontal cortex were significantly affected by the fidgeting conditions. The effects of the fidgeting condition on prefrontal brain activities depended on the age group. With the fidgeting intervention, older adults revealed increased brain activation in the prefrontal cortex compared to no fidgeting condition, whereas younger adults showed the opposite pattern. There were no significant differences in cognitive performance due to fidgeting. Conclusions: The results indicate that chair-based fidgeting may increase the prefrontal brain activation of older adults without negatively affecting cognitive performances compared to the conventional sitting workstation. In other words, additional fidgeting activity did not disturb the sedentary work but induced more engagement in a brain activity. This intervention may be beneficial in preventing or improving cognitive deficits by alternating and involving more dynamic prefrontal brain activity. Therefore, this research may provide a starting point to develop better cognitive treatment approaches to support people with speech or language related cognitive deficits.
The influence of age and gender on full range of motion of the whole body
Jaejin Hwang,Doo-Hwan Kwak,Jae-Min Woo,M.-C. Jung 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.5
Objective: The purpose of this study was to evaluate the effect of age and gender on full Range of Motion (ROM) of the whole body. Background: Age and gender was known important factors affecting ROM. Previous studies mainly focused on evaluating ROM for Western subjects using a one-dimensional measuring technique. Thus, it would be interesting to study the age and gender effect on ROM for Asian population using a three-dimensional measuring technique. Method: Twenty male and 20 female aged 20 to 63 participated in this study. Subjects performed a total of 8 voluntary motions in sagittal plane for 8 segments and it was measured by three-dimensional motion capture system (VICON, UK) with 9 cameras. Results: The result showed that age was significant for 5 motions whereas gender was significant for 2 motions. Young and female group generally displayed larger ROM than old and male groups. The age effect on ROM was high in flexion/extension of the hand, trunk, and head while the gender effect on ROM was high in flexion of lower arm and flexion/extension of upper leg. Conclusion: The age effect on ROM was higher than the gender effect on ROM and the magnitude of ROM difference was depending upon segments and motions. Application: The result of this study would beuseful information for designing workplace for Asian worker population that is associated with age and gender.
High-mobility two-dimensional electron gas at the PbZr0.5Ti0.5O3/BaSnO3 heterostructure
Hwang Jaejin,Byun Jinho,Kim Hyejung,Lee Jaekwang 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.84 No.1
The two-dimensional electron gas (2DEG) formed at the oxide heterointerface between LaAlO3 (LAO) and SrTiO3 (STO) has gained signifcant attention due to its exotic physical properties and interfacial conductivity. However, the 2DEG resides in a weakly dispersive Ti-d band, resulting in relatively low mobility. This limitation hampers its practical applications in future oxide electronics. To enhance the mobility of the 2DEG, we propose the use of BaSnO3 (BSO) as a novel host material with a highly dispersive conduction Sn-5 s band. The s orbitals in BSO are signifcantly more delocalized than d orbitals, leading to a higher dispersion of the conduction band. Our frst-principles density functional theory (DFT) calculations reveal that a high-mobility n-type 2DEG can indeed be formed near the PbZr0.5Ti0.5O3/BSO interface. The polar feld of the ferroelectric PbZr0.5Ti0.5O3 generates an interfacial conducting state in BSO, resulting in a high-mobility n-type 2DEG within the highly dispersive Sn-5 s band.
황재진(JaeJin Hwang),최명렬(Myung-Ryul Choi) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅰ
인터넷 보안에 대한 중요성이 나날이 증가하고 있으며 이러한 인터넷 보안 문제의 해 결책으로 개발된 IPSec은 IP 계층에서 보안서비스를 제공하기 위하여 AH와 ESP를 사용하여 보안연계(Security Association) 서비스를 제공한다. 본 논문에서는 32-bit 데이터 버스를 이용하여 새로운 AES 로 채택된 Rijndael 암호 알고리즘과 HMAC-SHA-1 인증 알고리즘을 통합시킨 IPSec 암호 프로세서를 구현하였다. Xilinx ISE 5.2i를 사용하여 VHDL로 설계하였고, ModelSim으로 시뮬레이션 검증을 수행하였으며 Xilinx사의 Vertex XCV1000E로 구현하였다. 본 논문에서 구현한 IPSec 암호 프로세서는 WLAN이나 VPN, Firewall 등에 응용될 수 있을 것이다.
황재진(Jaejin Hwang),정영주(Young-Ju Jeong),이동욱(Dongwook Lee),주석호(Seokho Ju),정명철(Myung-Chul Jung) 대한산업공학회 2018 대한산업공학회지 Vol.44 No.5
The objective of this study was to evaluate the effect of the recessed handle height and stature on the joint flexion angle, joint flexion moment, muscle activity of the upper extremities and low back, satisfaction, and preferred range of handle height during user’s door opening task of the French door refrigerator. The repeated-measures laboratory study was conducted with 28 participants. The results showed that joint angle, joint moment, and muscle activity were significantly decreased, and satisfaction was increased as the handle height increased. The middle stature group showed lower muscle activity of the wrist compared to short and tall stature groups. Based on the psychophysics, tall stature group had approximately 3 times greater range of preferred handle height than short stature group. Considering biomechanics and psychophysics, the recommendable range of the recessed handle height was 800mm~860mm. These results can be useful to design and improve the handles of the refrigerators.
Off-Resonant Third-Order Optical Nonlinearities of Au:SiO2 Nanocomposite Films
Hwang Woon Lee,Fabian Rotermund,Hanjo Lim,Jaejin Lee,Soonil Lee,Sunghun Cho 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I
Metal nanocomposites containing Au nanoparticles embedded in SiO$_2$ were deposited on fused silica substrates by alternating sputtering of SiO$_2$ and Au at a substrate temperature of 300 $^\circ$C and a constant volume fraction of 1 \%. The nanocomposite films were prepared with different Au mean diameters between 2.3 nm and 5.7 nm while the overall thickness was kept constant at 600 nm. The linear absorption peaks induced by surface plasmon resonance were shifted toward longer wavelengths from 500 nm to 560 nm with increasing Au particle sizes. To estimate third-order optical nonlinearities of the Au:SiO$_2$ nanocomposite films, such as nonlinear refraction and nonlinear absorption at off-resonant wavelengths, we applied the $z$-scan technique by using laser pulses from a Kerr lens mode-locked femtosecond Ti:sapphire laser at 780 nm and 820 nm and its second harmonics at 410 nm. The sign and the magnitude of experimentally obtained off-resonant third-order susceptibilities were compared with the theoretical results.
Feasibility Study for the Monitoring of Urea in Dialysate Solution using Raman Spectroscopy
Jaejin Kim,Jinyoung Hwang,Yongdan Kim,정회일 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.3
We have determined the urea concentration in an aqueous solution using Raman spectroscopy by incorporating a Teflon tube as an effective intensity correction standard as well as sample container. A non-overlapping Teflon band was used as the reference peak to correct Raman intensity variations that occasionally resulted from changes in laser power. To increase the sensitivity, we positioned a copper reflector inside the Teflon tube to maximize the collection of Raman scattering. The obtained accuracy using Raman spectroscopy was 0.53mM, close to the range of accuracy of previous NIR studies (0.15-0.52 mM).