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( 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.
Ryu, Jiheon,Lee, Jongwon,Chin, Huicheol,Yeom, Jae-Hyun,Kim, Hyo-Tae,Kwon, Hae-Ok,Han, Seung Ho,Choi, Jin Soo IEEE 2013 IEEE transactions on plasma science Vol.41 No.8
<P>This paper proposes a paraboloidal reflector-based integrated antenna-source (IAS) system for increasing the strength of radiated electric fields in ultrawideband (UWB) pulses. With the transient analysis of a paraboloidal structure, the reflector for an omnidirectional radiation source is designed. The paraboloidal reflector-based IAS system is structurally uncomplicated and compact. The proposed high power wideband radiator has a peak value of 42.9 kV/m at a distance of 40 m and a center frequency of 1.1 GHz. Thus, the strength of electric field rises by 8.9 times compared with that of the system without reflector. It is numerically and experimentally proved that both the far voltage and the UWB gain are significantly increased.</P>
Hyperarousal-state of Insomnia Disorder in Wake-resting State Quantitative Electroencephalography
Gyutae Jang,Han Wool Jung,Jiheon Kim,Hansol Kim,Ji‑Hyeon Shin,Chan-Hyung Kim,Do-Hoon Kim,Sang-Kyu Lee,Daeyoung Roh 대한정신약물학회 2024 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.22 No.1
Objective: Insomnia is associated with elevated high-frequency electroencephalogram power in the waking state. Although affective symptoms (e.g., depression and anxiety) are commonly comorbid with insomnia, few reports distinguished objective sleep disturbance from affective symptoms. In this study, we investigated whether daytime electroencephalographic activity explains insomnia, even after controlling for the effects of affective symptoms. Methods: A total of 107 participants were divided into the insomnia disorder (n = 58) and healthy control (n = 49) groups using the Mini-International Neuropsychiatric Interview and diagnostic criteria for insomnia disorder. The participants underwent daytime resting-state electroencephalography sessions (64 channels, eye-closed). Results: The insomnia group showed higher levels of anxiety, depression, and insomnia than the healthy group, as well as increased beta [t (105) = −2.56, p = 0.012] and gamma [t (105) = −2.44, p = 0.016] spectra. Among all participants, insomnia symptoms positively correlated with the intensity of beta (r = 0.28, p < 0.01) and gamma (r = 0.25, p < 0.05) spectra. Through hierarchical multiple regression, the beta power showed the additional ability to predict insomnia symptoms beyond the effect of anxiety (ΔR2 = 0.041, p = 0.018). Conclusion: Our results showed a significant relationship between beta electroencephalographic activity and insomnia symptoms, after adjusting for other clinical correlates, and serve as further evidence for the hyperarousal theory of insomnia. Moreover, resting-state quantitative electroencephalography may be a supplementary tool to assess insomnia.
Immediate Effects of Asymmetric Chewing on Temporomandibular Joint Kinematics
( Tae-joon Um ),( Han-seung Choi ),( Dong Yeop Lee ),( Jae Ho Yu ),( Jin Seop Kim ),( Seung Gil Kim ),( Jiheon Hong ) 대한물리치료학회 2023 대한물리치료학회지 Vol.35 No.6
Purpose: This study investigated the immediate biomechanical effects of unilateral mastication for 10 minutes on the temporomandibular joint (TMJ) with 21 healthy adult participants. Methods: The gum group chewed gum on the right side for 10 minutes, and the control group rested for 10 minutes. Biomechanical data were obtained using a three-dimensional infrared camera before and after intervention. An independent t-test assessed the variation of kinematic data to identify differences between before and after intervention. Results: Among biomechanical variables, the gum group’s length of the left forehead middle region and the temporomandibular joint angle decreased compared to the control group (p<0.05). Conclusion: Caution with unilateral masticatory activity is recommended, as unilateral mastication causes biomechanical changes due to excessive load on the soft tissues of the contralateral TMJ.