Because magnets fabricated using Nd-Fe-B exhibit excellent magnetic properties, this novel material is used in various high-tech industries. However, because of the brittleness and low formability of Nd-Fe-B magnets, the design freedom of shapes for improving the performance is limited based on conventional tooling and postprocessing. Laserpowder bed fusion (L-PBF), the most famous additive manufacturing (AM) technique, has recently emerged as a novel process for producing geometrically complex shapes of Nd-Fe-B parts owing to its high precision and good spatial resolution. However, because of the repeated thermal shock applied to the materials during L-PBF, it is difficult to fabricate a dense Nd-Fe-B magnet. In this study, a high-density (>96%) Nd-Fe-B magnet is successfully fabricated by minimizing the thermal residual stress caused by substrate heating during L-PBF.
The original focus of this study was to investigate the immediate effects of lumbar rotational mobilization on the one-legged standing ability. Fifteen subjects (6 men and 9 women, mean age = 22.77 (SD = 1.21), mean height = 165.46cm (SD = 11.65), mean weight = 61.46kg (SD = 8.29) volunteers from healthy individuals were recruited and randomized to a lumbar rotational mobilization (LRM) group and a trunk rotational exercise (TRE) group. Mobilization (grade 3 or 4) was applied to the LRM group on the lumbar spine (L1 to L5) in a side-lying, and trunk twist exercise (left and right side) was applied the to the TRE group with lunge position. Center of pressure (COP) and the velocity of the center of pressure (VCOP) of each participant were measured as a balance ability through one leg standing position. Results are as follows. In within-group difference, the COP of the LRM group reduced during standing with the right foot, but the VCOP change of the LRM was not statistically significant. In between-groups difference, COP of TRE group was decreased compared with LRM group only during left leg standing in the eyes (p <.05). The results of this study suggest that LRM is more effective than TRE in improving balance ability.
The main focus of this study was to investigate effects of lumbar central posteroanterior (PA) mobilization on isometric knee extension (IKE) ability and patellar tendon reflex amplitude (PTRA) in healthy university students. University students aged 19-26 (male; 10, female; 10) without any neurological disorders participated voluntarily and excluded the subjects with abnormal reflexes. The participation had an average body mass of 64.25±13.52 kg, an average height of 1.66±0.08m, and an average Body Mass Index (BMI) of 23.07±3.21. Every student was randomly assigned to be received squatting exercise and PA mobilization sequentially with 5 days of wash out period. IKE and PTRA were not significantly different between the two groups after the intervention. All the outcome measures were arranged into two data groups; PA mobilization and squatting exercise data group. In the PA mobilization data group, IKE and PTRA significantly increased after the intervention, however, these aspects were decreased in the squatting exercise group. These findings suggest that IKE and PTRA increase immediately after PA mobilization, therefore PA mobilization could be a valuable topic for controlled clinical trials.
The purpose of this study was to measure the mean peak mobilization forces to the cervical spine 3-5 with grade III and grade IV of posteroanterior (PA) mobilization. Asymptomatic 25 college subjects were participated in the trial and eligible physical therapists performed cervical mobilization. The mean peak mobilization force was measured during the PA mobilization with grade III and grade IV by attaching a flexible force transducer over the C3-C5 spinous process. Three cycles of PA mobilization were performed in each spine and the therapist took approximately 2.5s to complete mobilization. After applying the grade III mobilization to the C3-C5, 30 minutes later, the grade IV mobilization was applied to the same area again. There were no significant differences between C3, C4 and C5 during grade III as well as grade IV. Upon comparing the mean peak force of grade III with mean peak force of grade IV at the C3, C4 and C5 respectively, an insignificant difference was also observed. The mean peak mobilization force was 4.53±1.79 N at the C3, 5.10±1.91 N at the C4, and 5.17±2.63 N at the C5 during grade III force was applied. The mean peak mobilization force was 4.40±1.56 N at the C3, 5.53±2.01 N at the C4, and 5.38± 2.73 N at the C5 during grade IV force was applied. This study suggested that the mean peak force of the grade III and grade IV mobilization in the C3-C5 was similar each other, also there was no difference between mean peak force of grade III and grade IV on C3, C4 and C5.
A strain-gradient crystal plasticity finite element method(SGCP-FEM) was utilized to simulate the compressive deformation behaviors of single-slip, (111)[101], oriented FCC single-crystal micro-pillars with two different slip-plane inclination angles, 36.3o and 48.7o, and the simulation results were compared with those from conventional crystal plasticity finite element method(CP-FEM) simulations. For the low slip-plane inclination angle, a macroscopic diagonal shear band formed along the primary slip direction in both the CP- and SGCP-FEM simulations. However, this shear deformation was limited in the SGCP-FEM, mainly due to the increased slip resistance caused by local strain gradients, which also resulted in strain hardening in the simulated flow curves. The development of a secondly active slip system was altered in the SGCP-FEM, compared to the CP-FEM, for the low slip-plane inclination angle. The shear deformation controlled by the SGCP-FEM reduced the overall crystal rotation of the micro-pillar and limited the evolution of the primary slip system, even at 10% compression.
The purpose of this study was to examine the effects of communitybased rehabilitation (CBR) program on activities of daily livings (ADLs), quality of life and assistive technology satisfaction for disabled adults in South Korea. Fourteen community-dwelling subjects were participated in a home-based rehabilitation program which performed once a month for 2 months. The outcome measures included Modified Barthel Index (MBI) for assessing ADLs, EuroQol five-dimensions questionnaire (EQ- 5D) for quality of life (QoL) and Quebec User Evaluation of Satisfaction with assistive Technology 2.0 (QUEST 2.0) for assistive technology. Significant improvements in ADLs, quality of life and assistive technology satisfaction were observed after the program. This study indicated that community-based rehabilitation program is an effective method for improving ADLs, quality of life and assistive technology satisfaction for adults with disabilities.
A strain-gradient crystal plasticity constitutive model was developed in order to predict the Hall Petch behavior of a Ni-base polycrystalline superalloy. The constitutive model involves statistically stored dislocation and geometrically necessary dislocation densities, which were incorporated into the Bailey-Hirsch type flow stress equation with six strength interaction coefficients. A strain-gradient term (called slip-system lattice incompatibility) developed by Acharya was used to calculate the geometrically necessary dislocation density. The description of Kocks-Argon-Ashby type thermally activated strain rate was also used to represent the shear rate of an individual slip system. The constitutive model was implemented in a user material subroutine for crystal plasticity finite element method simulations. The grain size dependence of the flow stress (viz., the Hall- Petch behavior) was predicted for a Ni-base polycrystalline superalloy NIMONIC PE16. Simulation results showed that the present constitutive model fairly reasonably predicts 0.2%-offset yield stresses in a limited range of the grain size.