• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.310-316
• /
• 2016

We propose a novel contact-free transportation system in which an axial electrodynamic wheel is applied as an actuator. When the electrodynamic wheel is partially overlapped by a fixed conductive plate and rotates over it, three-axis magnetic forces are generated on the wheel. Among these forces, those in the gravitational direction and the lateral direction are inherently stable. Therefore, only the force in the longitudinal direction needs to be controlled to guarantee spatial stability of the wheel. The electrodynamic wheel consists of permanent magnets that are repeated and polarized periodically along the circumferential direction. The basic geometric configuration and the pole number of the wheel influence the stability margin of a transportation system, which would include several wheels. The overlap region between the wheel and the conductive plate is a dominant factor affecting the stiffness in the lateral direction. Therefore, sensitivity analysis for the major parameters of the wheel mechanism was performed using a finite element tool. The system was manufactured based on the obtained design values, and the passive stability of a moving object with the wheels was verified experimentally.

• Journal of Korean Orthopaedic Sports Medicine
• /
• v.9 no.2
• /
• pp.91-97
• /
• 2010

Purpose: The purpose of this study was to evaluate the results of treatment for longitudinal meniscal tear in ACL rupture patients by clinical evaluation and $2^{nd}$ look arthroscopy. Materials and Methods: Among the patients who underwent surgery due to ACL rupture and longitudinal meniscal tear between 2002~2009, 32 patients were selected for the study. The patients were devided into three groups; group 1 had repair, group 2 had partial menisectomy due to impossible to repair, group 3 had conservative treatment due to stable meniscus. Comparative retrospective analysis was applied with KT 1000 arthrometer, Lysolm' score, Tegner activity score, IKDC subjective score, and $2^{nd}$ look arthroscopy. Results: Lysolm' score, Tegner activity score, IKDC subjective score showed no statistical difference in all three groups. KT-1000 side to side difference improved from 6.2, 6.15, 6.38 before surgery to 2.56, 2.49, 2.58 after surgery in group 1, 2, and 3, respectively. In group 1, second-look arthroscopy revealed complete healing in 12 patients, incomplete healing without any clinical symptoms in 2, and healing failure in 1. In group 2, second-look arthroscopy showed partial regeneration on margin of meniscectomy. In group 3, second-look arthroscopy revealed complete healing in 2 patients, while 4 showed incomplete healing so that have repaired. Conclusion: In the study, the outcome was better when the stable longitudinal meniscal tear on posterior horn with ACL rupture had active treatment.

• Journal of Periodontal and Implant Science
• /
• v.52 no.2
• /
• pp.91-115
• /
• 2022

Purpose: This systematic review aimed to compare the efficacy, defined in terms of the mean percentage of root coverage (mRC), of surgical treatment approaches combined with adhesive restorations of non-carious cervical lesions (NCCLs) to that of root coverage alone in patients with a single gingival recession (GR) and NCCL. Methods: A literature search was conducted to identify longitudinal studies reporting the mRC following treatment for the correction of GR defects associated with NCCLs using a combination of surgical and restorative techniques in systemically and periodontally healthy patients. Results: The search resulted in the retrieval of 12,409 records. Seven publications met the inclusion criteria for the qualitative synthesis of data. The mRCs ranged from 69% to 97%. In the medium term, the gingival margin position was more stable when a connective tissue graft (CTG) was used, independently of whether restoration of teeth with NCCLs was performed. Conclusions: The strength of the evidence was limited by methodological heterogeneity in terms of study design as well as the unit and period of analysis, which precluded a metaanalysis. Although no definitive conclusion could be drawn due to the lack of sufficient evidence to estimate the effectiveness of the interventions, CTG-based procedures contributed to gingival margin stability regardless of the performance of restoration to treat NCCLs.

• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.3
• /
• pp.219-231
• /
• 2014

We develop a preliminary design optimization procedure in this paper regarding the wing planform in a solar-powered high-altitude long-endurance unmanned aerial vehicle. A high-aspect-ratio wing has been widely adopted in this type of a vehicle, due to both the high lift-to-drag ratio and lightweight design. In the preliminary design, its characteristics need to be addressed correctly, and analyzed in an appropriate manner. In this paper, we use the three-dimensional Euler equation to analyze the wing aerodynamics. We also use an advanced structural modeling approach based on a geometrically exact one-dimensional beam analysis. Regarding the structural integrity of the wing, we determine detailed configuration parameters, specifically the taper ratio and the span length. Next, we conduct a multi-objective optimization scheme based on the response surface method, using the present baseline configuration. We consider the structural integrity as one of the constraints. We reduce the wing weight by approximately 25.3 % from that in the baseline configuration, and also decrease the power required approximately 3.4 %. We confirm that the optimized wing has sufficient flutter margin and improved static longitudinal/directional stability characteristics, as compared to those of the baseline configuration.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.5
• /
• pp.18-27
• /
• 2005

Airfoils with improved longitudinal static stability were designed for a WIG craft through aerodynamic design optimization. The response surface method is coupled with NURBS-based shape functions and Navier-Stokes flow analysis. The procedure runs in the network-distributed design framework of commercial-code based automated design capability to enhance computational efficiency and robustness.Lift maximization design maintaining similar static margin to a DHMTU airfoil successfully produced a new airfoil shape characterized by pronounced front-loading and the well-known reflexed aft-camber line. Another airfoil design of lower variation in pitching moment during take-off showed weakened front-loaded characteristics and hence decreased lift slightly. Investigations using the present design methodology on an existing optimization result based on potential flow analysis and NACA-type geometry generation demonstrated significance of carrying various geometry generations and more realistic flow analysis with optimization.