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표면매입 탄소섬유판으로 보강된 철근콘크리트 부재의 휨 거동에 관한 실험연구
임동환 ( Lim¸ Dong-hwan ),남민희 ( Nam¸ Min-hee ) 한국구조물진단유지관리공학회 2008 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.12 No.1
본 연구에서는 탄소섬유판이 표면 매입된 철근 콘크리트 보의 휨 거동 효과를 고찰하였다. 이를 위하여, 탄소섬유판이 표면 매입된 T 형 철근 콘크리트 보를 제작하여 실험을 수행하였다. 본 연구 결과, 표면매입(NSM) 탄소섬유판으로 보강된 철근콘크리트 부재의 휨 강성 및 극한강도는 섬유판으로 보강되지 않은 보에 비하여 크게 증진되며, 그 최대 증가율은 보강되지 않은 부재의 경우보다 약 247%로 나타났다. 위 철근콘크리트 부재의 파괴는 부재 길이 방향으로 섬유 소선이 풀리는 표면매입 탄소 섬유판의 파괴로 시작되며, 탄소섬유판의 파단이 이어지는 2차 파괴가 발생하였다. 표면매입 탄소섬유판은 콘크리트와의 완정한 합성거동을 유도하여 따라서 탄소섬유판을 표면에 매입하는 방식은 노후 구조물 보강방식으로 매우 효과적인 것으로 판단된다.
Donghwan Park(Donghwan Park),Kang-Seong Lee(Kang-Seong Lee) 물리치료재활과학회 2024 Physical therapy rehabilitation science Vol.13 No.1
Objective: The objective of this study was to investigate the effect of the thoracic mobility exercise program on pain, proprioception, and static balance ability in patients with non-specific chronic low back pain. Design: Randomized controlled trial design. Methods: Thirty patients with non-specific chronic low back pain participated in this study. The participants were randomized into the thoracic mobility exercise group (n=15) and the lumbar stabilization exercise group (n=15). Both groups received traditional physical therapy for 30 minutes per session. In addition, the thoracic mobility exercise group and the lumbar stabilization exercise group each exercise 3 times a week for 6 weeks. All participants were measured visual analog scale, proprioception test, and static balance ability before and after the intervention. Results: After 6 weeks of interventions, the thoracic mobility exercise group showed greater improvement in visual analog scale, proprioception test, and static balance ability than the LSE group (p<0.05). Further, the thoracic mobility exercise group had significant Enhancements in all measured variables compared to the baselinetest (p<0.05). However, the lumbar stabilization exercise group had significant improvement only visual analog scale, and static balance ability compared to the baselinetest (p<0.05). Conclusions: Our investigation demonstrates that the thoracic mobility exercise is an effective intervention method for improving pain, proprioception, and static balance ability in patients with non-specific chronic low back pain.
Numerical modeling and simulation technique in time-domain for multibeam echo sounder
Donghwan Jung,Jeasoo Kim,Gihoon Byun 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.2
A Multibeam Echo Sounder (MBES) is commonly used for rapid seafloor mapping. We herein present a time-domain integrated system simulation technique for MBES development. The Modeling and Simulation (M&S) modules consist of four parts: sensor array signal transmission, propagation and backscattering modeling in the ocean environment, beamforming of the received signals, and image processing. Also, the simulation employs a ray-theory-based algorithm to correct the reconstructed bathymetry, which has errors due to the refraction caused by the vertical sound velocity profile. The developed M&S technique enables design parameter verification and system parameter optimization for MBES. The framework of this technique can also be potentially used to characterize the seabed properties. Finally, typical seafloor images are presented and discussed.
Optimal transmission policies for MOT in T-DMB
Donghwan Lee,Jihoon Choi,Kyunghwi Kim,Wonjun Lee,Choonhwa Lee IEEE 2007 IEEE communications letters Vol.11 No.12
<P>The Multimedia Object Transfer (MOT) protocol in Terrestrial Digital Multimedia Broadcasting (T-DMB) systems inherently does not facilitate return paths in data transmission and therefore additional policies are required to envision further efficient reliable media broadcasting. This letter proposes novel optimal transmission policies for MOT standard definition in T-DMB. The proposed broadcasting policies drastically enhance the capability of conventional MOT protocol.</P>