• Journal of the Korea Society for Simulation
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• v.19 no.2
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• pp.9-16
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• 2010

This study presents a system for validating the PLC code in the virtual environments of automobile trim line. There have been considerable efforts to develop standard PLC editors for saving human power and PLC test time. However, it was difficult to apply the PLC editor on a real shop floor environment. A virtual equipment was developed to communicate with the PLC module of a shop floor and to make up the connectivity environment by a special protocol. We can validate the code without launching real equipments because the PLC module and the virtual equipment is able to be controlled in real time by the OPC protocol. An experimental model is applied to the final assembly line of an automotive industry and validated by using DELMIA Automation. In conclusion, the system is valuable in the process of PLC codes validation and virtual equipments operation. This system would reduce the development time of the PLC codes and improve the productivity and the integrity of the PLC codes.

• Journal of the Korean Society of Physical Medicine
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• v.19 no.1
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• pp.131-142
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• 2024

PURPOSE: This study was a systematic review and meta-analysis of the literature comparing the differences between task-oriented treadmill training and general treadmill training for stroke patients. METHODS: Literature published in the Cumulated Index to Nursing and Allied Health Literature (CINAHL), Embase, Physiotherapy Evidence Database (PEDro), and PubMed was reviewed. A total of 1,163 studies were initially retrieved, of which eight articles were included in the final review. A quality assessment of the included studies was conducted using the Risk of Bias (RoB) 2.0 tool, and Duval and Tweedie's trim and fill method was used to evaluate publication bias. Data analysis was performed using R studio 4.2.1. RESULTS: According to the quality assessment using RoB 2.0, three articles were evaluated as low risk, two as of some concern, and three as high risk. The overall effect size of task-oriented tradmill training was .35. Regarding gait function, the values were .76, .25, and .40, respectively, for gait endurance, gait speed, and gait pattern. According to Duval and Tweedie's trim and fill method, no publication bias was observed. CONCLUSION: Study findings indicate that task-oriented treadmill training is the most effective intervention for improving gait endurance in patients with stroke. Therefore, applying this intervention to patients with stroke in the community is recommended.

• Journal of Aerospace System Engineering
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• v.18 no.4
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• pp.18-26
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• 2024

This paper describes the results of a study on Generic Quad Tilt Rotor UAM aircraft, focusing on nonlinear mathematical modeling and the development of real-time simulation software. In this research, we designed a configuration for a Generic Quad Tilt Rotor eVTOL UAM aircraft based on NASA's UAM mission requirements. We modeled the aerodynamics using a database, the prop-rotor dynamics with a thrust database, and included a ground reaction and atmospheric model in the flight model. We defined the control concept for various modes(helicopter mode, transition mode, and airplane mode), derived tilt angle corridors, and formulated flight control requirements. The resultant real-time flight simulation software not only performs trim analysis for Tilt Rotor UAM aircraft but also predicts handling qualities, optimizes tilt angle scheduling based on dynamic characteristics, designs and validates flight control laws for helicopter, transition, and airplane modes, and facilitates flight training through simulator integration.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.1
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• pp.1-10
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• 2013

This is a written version of the keynote speech delivered at the International Symposium on Hypersonic Aerothermodynamics - Recent Advances held in Bangalore, India, from December $6^{th}$ to $10^{th}$, 2012. In this document, what was accomplished in the past, the present status, and what is expected in the future in the field of hypersonic aerothermodynamics are reviewed. Solved problems are categorized into four items; unsolved problems into twelve items, and emerging problems into four items. Removing one degree uncertainty in trim angle of attack, studying the thermochemical phenomena in a hydrogen-helium-methane mixture, and entry flights of meteoroids are cited as the tasks for the future.

• Journal of computational fluids engineering
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• v.19 no.3
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• pp.62-68
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• 2014

The aerodynamic and noise calculations were performed through the CFD-CSD loose coupling methodology. In the loose coupling process, the trimmed rotor airloads were predicted by the in-house CFD code based on unstructured overset meshes, and the trim of the rotorcraft and the aeroelastic deformation of rotor blades were accounted with the CAMRAD II rotorcraft comprehensive code. The set of codes was used to analyze the HART-II baseline test condition. The effect of grid resolution and time step was examined and the loose coupling approach was found to be stable and convergent for the case. Comparison of the resulting sectional airloads, structural deformations, the noise carpets and the wake geometry with experimentally measured data was presented and showed the good agreement.

• Journal of the Korea Society of Computer and Information
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• v.22 no.4
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• pp.115-122
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• 2017

The purpose of this study was to evaluate the effect of job satisfaction on turnover intention and organizational commitment in nurses through a systematic literature review and meta-analysis. For the study purpose, 26 studies were selected through a systematic process of using several databases and used to estimate the effect size of correlation between 3 variables. Meta-analysis was applied by usingcrandom effects model, and effect sizes on three types were calculated. Results are as follows. First, the effect size of correlation between job satisfaction and turnover intention is -.58. Second, the effect size of correlation between job satisfaction and organizational commitment is .77. Third, for the organizational commitment and turnover intention relationship, the effect of correlation is -0.68. Furthermore, publication bias analysis were assessed the results by using the funnel plot, Egger's regression test, fail-safe N, and trim-and-fill test. Based on these results, implications for the study were discussed.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.1-8
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• 2009

This is a short review of how CFD contributed to hypersonic flights in the past 50 years. Two unexpected phenomena that occurred in the entry flights of the Apollo and Space Shuttle made us aware of the impact of the high temperature real-gas effects on hypersonic flights: pitching moment anomaly of up to 4 degrees, and radiation overshoot behind a shock wave. The so-called two-temperature nonequilibrium model was introduced to explain these phenomena. CFD techniques were developed to accommodate the two-temperature model. Presently, CFD can predict trim angle of attack to an accuracy of about 1 degree. A concerted effort was made to numerically reproduce the experimentally measured flow-field over a double-cone. As yet, perfect agreement between the experimental data and computation is not achieved. Scramjet technology development is disappointingly slow. The phenomenon of ablation during planetary entries is not yet predicted satisfactorily. In the future, one expects to see more research carried out on planetary entries and space tourism.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.177-181
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• 2003

Despite various forms have been developed and applied to ship hull forms, the superiority of hard chine type over other forms of fishing boat has been recognized so far. As one of the ways of forms for new concept fishing boat, this paper presents the result of a performance evaluation for newly developed forms of hull, appendage and deck house, which features that have esthetic forms.

• The KSFM Journal of Fluid Machinery
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• v.5 no.3 s.16
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• pp.25-32
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• 2002

Structural and dynamic analyses of inducer and impeller for an oxidizer turbopump are peformed to investigate the safety level of strength and vibration at a design point. Due to high rotational speed of turbopump, effects of centrifugal forces are carefully considered in the structural analysis. Hydrodynamic pressure is also considered as an external force applied to inducer and impeller blades. A three-dimensional Finite Element Method (FEM) is used for linear and nonlinear structural analyses with modified Newton-Raphson iteration method. After the nonlinear trim solution is obtained from the structural analysis, dynamic characteristics are obtained as a function of rotational speed from the linearized eigenvalue analysis at an equilibrium position. According to the results of numerical analysis, the safety margins of strength and vibration resonances are sufficient enough for safe operation within the requited life cycle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.2
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• pp.135-144
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• 2009

In this present work, spline FEA for the trimmed NURBS surface of the 2D linear elasticity problem is presented. The main benefit of the proposed method is that no additional efforts for modeling of trimmed NURBS surfaces are needed and the information of the trimming curves and trimmed surfaces exported from the CAD system can be directly used for analysis. For this, trimmed elements are searched by using NURBS projection scheme. The integration of the trimmed elements is performed by using the NURBS-enhanced integration scheme. The formulation of constructing stiffness matrix of trimmed elements is presented. In this formulation, the information of the trimming curve is used for calculating the Jacobian as well as for obtaining integration points. The robustness and effectiveness of the proposed method are investigated through various numerical examples.