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Detection and Quantification of Screw-Home Movement Using Nine-Axis Inertial Sensors
( Jeong Woo Jeon ),( Dong Yeop Lee ),( Jae Ho Yu ),( Jin Seop Kim ),( Jiheon Hong ) 대한물리치료학회 2019 대한물리치료학회지 Vol.31 No.6
Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conducted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement systems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p< 0.05). However, there was no significant difference in the transverse plane between the two systems (p >0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.
Ryu, Jiheon,Kim, Kiho,Lim, Tae Hyun,Kwon, Hae-Ok,Kuk, Jeong Hyeon,Choi, Jin Soo,Baek, Sung-Hyun,Yu, Jong-Won IEEE 2019 IEEE antennas and wireless propagation letters Vol.18 No.4
<P>This letter presents a directive integrated-antenna-source (DIAS) for a high-power ultrawideband parabolic reflector system. Unlike the previously developed omnidirectional integrated-antenna-source (OIAS) that leads to spillover loss in a high-power parabolic reflector system, the proposed DIAS reduces the spillover loss in the system. The DIAS is designed by cutting away the halves of the two electrodes in the OIAS. The DIAS-based reflector system was designed through numerical electromagnetic simulations. The proposed DIAS was fabricated for validation. The proposed DIAS shows 3 dB beamwidths on the <I>H</I>-plane and <I>E</I>-plane of 234° and 116°, respectively, in the peak electric-field patterns. In addition, the DIAS has a much smaller capacitance than the OIAS. The proposed DIAS-based reflector system has a peak electric-field strength of 39.5 kV/m at a distance of 40 m. The results show that, although the DIAS has a much smaller capacitance than the OIAS, the DIAS-based reflector system is capable of producing high-power electromagnetic pulses similar to those of the OIAS-based reflector system.</P>
Detection and Quantification of Screw-Home Movement Using Nine-Axis Inertial Sensors
Jeon, Jeong Woo,Lee, Dong Yeop,Yu, Jae Ho,Kim, Jin Seop,Hong, Jiheon The Korean Society of Physical Therapy 2019 대한물리치료학회지 Vol.31 No.6
Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conducted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement systems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p<0.05). However, there was no significant difference in the transverse plane between the two systems (p>0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.
Experimental analysis of lithium niobate CMP for room temperature bonding
조한철,Sukhoon Jeong,Jaehong Park,Hojun Lee,Jiheon Oh,Hyoungjae Kim,Haedo Jeong 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6
Lithium niobate (LN, LiNbO3) is a type of artificial crystal exhibition piezoelectricity, pyroelectric and ferroelectricity, which has been widely used in electronic components. To use in electronic components, a LN wafer has to be bonded to a Si substrate. Bonding of Si and LN allows for ease of micromachining a high quality electrically-sensitive thin film, as well as creating mechanically-rigid diaphragms. For this reason, Si combined with LN is desirable for microelectromechanical system (MEMS) devices such as a pressure sensors, microfluidic devices and optical data storage systems. However, the large difference in thermal expansion coefficient between Si and LN causes serious thermal stresses during the thermal-pressure bonding process which has generally been used. Therefore room temperature bonding would be the best candidate for making a strong and stress-free interface between Si and LN. Room temperature bonding requires a lower surface roughness and lower defect contact on the LN wafer surface than thermal bonding does. A chemical mechanical polishing (CMP) process produces a thin LN wafer with a high quality surface suited for room temperature bonding and with a suitale thickness that affects the sensitivity of the devices. Here LN wafers were polished using a colloidal silica slurry, resulting in a high material removal rate (MRR) and a fine surface quality under a condition of low pH, high abrasive concentration and low flow rate. The polishing mechanism of LN was investigated by mechanical, chemical and thermal analysis.
Design Principle of Fe-N-C Electrocatalysts: How to Optimize Multimodal Porous Structures?
Lee, Soo Hong,Kim, Jiheon,Chung, Dong Young,Yoo, Ji Mun,Lee, Hyeon Seok,Kim, Min Jeong,Mun, Bongjin Simon,Kwon, Soon Gu,Sung, Yung-Eun,Hyeon, Taeghwan American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.5
<P>The effect of porous structures on the electrocatalytic activity of N-doped carbon is studied by using electrochemical analysis techniques and the result is applied to synthesize highly active and stable Fe-N-C catalyst for oxygen reduction reaction (ORR). We developed synthetic procedures to prepare three types of N-doped carbon model catalysts that are designed for systematic comparison of the porous structures. The difference in their catalytic activity is investigated in relation to the surface area and the electrochemical parameters. We found that macro- and mesoporous structures contribute to different stages of the reaction kinetics. The catalytic activity is further enhanced by loading the optimized amount of Fe to prepare Fe-N-C catalyst. In both N-doped carbon and Fe-N-C catalysts, the hierarchical porous structure improved electrocatalytic performance in acidic and alkaline media. The optimized catalyst exhibits one of the best ORR performance in alkaline medium with excellent long-term stability in anion exchange membrane fuel cell and accelerated durability test. Our study establishes a basis for rationale design of the porous carbon structure for electrocatalytic applications.</P> [FIG OMISSION]</BR>
Kyung-eun Lee,So-eun Kim,Hyun-jeong Kim,Jeongwoo Jeon,Jiheon Hong,Jaeho Yu,Jinseop Kim,Seong-Gil Kim,Yeongyo Nam,Dongyeop Lee 한국융합학회 2024 미래기술융합논문지 Vol.3 No.1
본 연구에서는 체간 안정화 운동으로 대면, 비대면, 자가로 실시하였을 때 정적균형과 동적균형에 미치는 영향을 알아보고자 하였다. 본 연구는 신체적으로 질병이 없는 건강한 20대 36명을 모집하였다. 대상자들은 무작위로 세 그룹으 로 나뉘어져 체간 안정화 운동을 실시하였으며, 중재 전후 정적균형과 동적균형을 각각 측정하였다. 대면 및 비대면 그룹 에서 중재 전, 후 동적 균형 및 정적 균형이 유의하게 증가하였다. 자가운동군은 동적균형 3방향에서 유의하게 증가하였으 나 정적균형에서는 유의한 차이가 나타나지 않았다. 본 연구 결과, 대면 및 비대면 운동이 체간 안정화 운동이 정적균형과 동적균형 향상에 효과적임을 알 수 있었다. 이러한 결과는 균형 능력 향상을 위한 비대면 운동의 사용 가능성을 지지하며, 균형 능력 뿐만 아니라 다양한 신체 능력에 대한 비대면 운동의 효과에 대해 추가적인 연구가 필요합니다. Study of the effect of interbody stabilization exercises on the static and dynamic balance of face-to-face, non-face-to-face, and self-group. We recruited healthy young adults The subjects were randomly divided into three groups to perform inter-body stabilization exercises, and static and dynamic balance were measured, respectively, before and after intervention. In the Face to Face Group, dynamic balance significantly increased in the anterior and posteriomedial directions before and after intervention. There was also a significant increase in static balance. In the Non face to face Group, there was a significant increase in the three directions of dynamic and static balance. The self-exercise group significantly increased in three directions of dynamic balance, but there was no significant difference in static balance. No significant differences between groups were found in any variables. The results of this study showed that interbody stabilization exercises are effective in improving static and dynamic balance. In the face-to-face group, the inter-body stabilization exercise was effective in improving dynamic balance and static balance, and in the non-face-to-face group, the inter-body stabilization exercise was effective in improving dynamic balance and static balance. In the self-contained group, it was effective in improving dynamic balance.
Determination of tensile forces to enhance the supply stability of reinforced fiber
김건우,Jae-Wook Lee,Jinseok Jang,Myeong-Sik Jeong,Jooyoung Oh,Hoon Kang,Jiheon Kang,김형렬,유완석 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12
The manufacturing process of long fiber thermoplastic is initiated by supplying reinforced fiber wound in a spool dispenser. If problems such as tangling or kinking occur in the apparatus used for supplying the reinforced fiber in the long-fiber thermoplastic direct process, the productivity of the long-fiber thermoplastic decreases. Therefore, it is important to enhance the supply stability of reinforced fiber. In general, the increase in supply stability can be achieved by maintaining a steady balloon shape that is controlled by the unwinding velocity or tensile force of the reinforced fiber. In this research, the range of suitable tensile force was determined under the assumption that the unwinding velocity remained constant. The reinforced fiber was assumed to be inextensible, homogeneous, and isotropic and to have uniform density. The transient-state unwinding equation of motion to analyze the unwinding motion of reinforced fiber can be derived by using Hamilton’s principle for an open system in which mass can change within a control volume. In the process of solving the transient-state unwinding equation of motion, the exact two-point boundary conditions are adopted for each time step.