• Wind and Structures
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• v.34 no.6
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• pp.499-510
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• 2022

Computational Wind Engineering has rapidly grown in the last decades and it is currently reaching a relatively mature state. The prediction of wind loading by means of numerical simulations has been proved effective in many research studies and applications to design practice are rapidly spreading. Despite such success, caution in the use of simulations for wind loading assessment is still advisable and, indeed, required. The computational burden and the know-how needed to run high-fidelity simulations is often unavailable and the possibility to use simplified models extremely attractive. In this paper, the applicability of some well-known 2D unsteady RANS models, particularly the k-ω SST, in the aerodynamic characterization of extruded bodies with bluff sections is investigated. The main focus of this paper is on the drag coefficient prediction. The topic is not new, but, in the authors' opinion, worth a careful revisitation. In fact, despite their great technical relevance, a systematic study focussing on sections which manifest a fully detached flow configuration has been overlooked. It is here shown that the considered 2D RANS exhibit a pathological behaviour, failing to reproduce the transition between reattached and fully detached flow regime.

• New & Renewable Energy
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• v.20 no.2
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• pp.17-25
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• 2024

In this study, the effect of the time step specified in a computational fluid dynamics (CFD) simulation on load response is analyzed and the drag coefficients of the floating body of floating offshore wind turbines (FOWTs) are estimated. By evaluating the error in the FOWT load response and the change in the drag-coefficient values based on the density of the time intervals, this study aims to establish a time-interval setting that minimizes the time and cost of CFD simulations for selecting drag-coefficient values. Practical CFD utilization strategies necessary for the calibration of medium-to high-fidelity analysis tools are presented. Based on a comparative analysis of CFD simulations conducted at various time intervals, the results confirmed that under a certain time interval that sufficiently considers various factors, the accuracy of the FOWT response with respect to density shows minimal differences, thereby providing an efficient utilization method for CFD simulations in FOWT design and analysis.

• Archives of design research
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• v.19 no.1 s.63
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• pp.225-234
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• 2006

Product designers sketch various ideas of foreground figures(detail design) onto background figures(basic form) and evaluate numerous combinations of them in the late stages of design process. Designers have to test their ideas elaborately with a high-fidelity physical model that looks like a real product. However, due to the requirements of time and expense in making high-fidelity design models, it is impossible to evaluate such a number of combinatorial solutions of background and foreground figures. Contrary to digital models, physical design models are not easily modifiable and so designers cannot easily develope ideas through iterative design-evaluation process. To address these problems, we proposed a new concept 'Augmented Plasticity' that gives morphological editability to a rigid physical object using Augmented Reality technology and implemented the idea as Digital Skin system. Digital Skin system figures out the position and orientation of object surface with ARToolKit visual marker and superimposes a deformed surface image seamlessly using differential rendering method. We tried to apply Digital Skin system to detail design, redesign of product, and material exploration task. In consequence, it was found that Digital Skin system has potential to allow designers to implement and test their ideas very efficiently in the late stages of design process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.177-189
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• 2016

This study examined the effectiveness of maternity nursing simulations using a high-fidelity simulator for undergraduate nursing students. One-group pretest-posttest design was used. The simulation-based education program consisted of three sessions, including the clinical scenarios about prenatal, childbearing and postpartum care. The program provided for 3 weeks in November 2014. Data was collected before and after the simulation education using self-reported questionnaires, which included simulation effectiveness, problem solving ability, communication skills and self-confidence in maternity nursing. The data of 83 participants were analyzed using the IBM SPSS 20.0 program. After simulation education, the overall score of the simulation effectiveness was 17.4 out of 26.0. Communication skill (t=4.58, p=<.001) and self-confidence in maternity nursing (t=9.70, p=<.001) increased significantly in the posttest. On the other hand, there was no significant change in the problem solving ability. The simulation effectiveness correlated significantly with the problem solving ability (r=.494, p<.001), communication skill (r=.361, p<.001), and self-confidence in maternity nursing (r=.497, p<.001) after simulation-based education. These findings suggest that the high-fidelity simulation in maternity nursing education could be used not only to enhance the nursing competency, but also to deal with the limitations of the clinical practicum in the current situation.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.241-250
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• 2007

In case of retrofitting a concrete structure subjected to blast load by using retrofit materials such as FRP (fiber-reinforced polymer), appropriate ductility as well as raising stiffness must be obtained. But the previous approximate and simplified models, which have been generally used in the design and analysis of structures subjected to blast load, cannot accurately consider effects on retrofit materials. Problems on the accuracy and reliability of analysis results have also been pointed out. In addition, as the response of concrete and reinforcement on dynamic load is different from that on static load, it is not appropriate to use material properties defined in the previous static or quasi-static conditions to in calculating the response on the blast load. In this study, therefore, an accurate HFPB (high fidelity physics based) finite element analysis technique, which includes material models considering strength increase, and strain rate effect on blast load with very fast loading velocity, has been suggested using LS-DYNA, an explicit analysis program. Through the suggested analysis technique, the behavior on the blast load of retrofitted concrete walls using CFRP (carbon fiber-reinforced polymer) and GFRP (glass fiber-reinforced polymer) have been analyzed, and the retrofit capacity analysis has also been carried out by comparing with the analysis results of a wall without retrofit. As a result of the analysis, the retrofit capacity showing an approximate $26{\sim}28%$ reduction of maximum deflection, according to the retrofit, was confirmed, and it is judged ate suggested analysis technique can be effectively applicable in evaluating effectiveness of retrofit materials and techniques.

• Journal of The Korea Institute of Healthcare Architecture
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• v.26 no.3
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• pp.17-26
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• 2020

Purpose: This paper presents research evidence that the environmental design of the doffing area in a biocontainment unit (BCU) can have a measurable impact on increasing the safety of frontline healthcare workers (HCW) during doffing of high-level personal protective equipment (PPE), and proposes optimized biocontainment unit design. Methods: From 2016 to 2019, The SimTigrate Design Lab conducted 3 consecutive studies, focusing on ways in which the built environment may support or hinder safe doffing. In the first study, to identify the risky behaviors, we observed 56 simulation exercises with HCWs in 4 BCUs and 1 high-fidelity BCU mockup. In the second study, we tested the effectiveness of a redesigned doffing area on improving the HCWs performance and used simulation, observation, and rapid prototyping in 1 high-fidelity mockup of a doffing area. In a follow-up study, we used simulation and co-design with HCWs to optimize the design of a safer doffing area in a full-size pediatric BCU mock-up. Results: We identified 11 specific risky behaviors potentially leading to occupational injury, or contamination of the PPE, or of the environment. We developed design strategies to create a space for safer doffing. In the second study, in a redesigned doffing area, the overall performance of HCW improved, and we observed a significant decrease in the number of risky behaviors; some risky behaviors were eliminated. There was a significant decrease in physical and cognitive load for the HCWs. Finally, we propose an optimized layout of a BCU for a safer process of PPE doffing. Implications: The proposed BCU design supports better staff communication, efficiency, and automates safer behaviors. Our findings can be used to develop design guidelines for spaces where patients with other highly infectious diseases are treated when the safety of the patient-facing HCWs is of critical importance.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.496-499
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• 1997

This paper describes the operating software of a motion system developed for a driving simulator, consisting of a six degree of freedom Stewart platform driven hydraulically. The drive logic, consisting of an washout algorithm, inverse kinematic analysis, and a control algorithm, has been developed and applied for creating high fidelity motion cues. The basic environment of the operating software is based on LabVIEW 4.0 and DLL modules compiled by Fortran.

• Proceedings of the IEEK Conference
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• summer
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• pp.233-236
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• 2004

This paper proposes new method for the enhancement of nonexistent high frequency spectral contents from low sample rate audio signal. For example, Due to the protocol constraint, the audio bandwidth of MP3 is restricted to 16Khz. Although band-restricted MP3 audio provide savings of storage space and network bandwidth, it suffers a major problem of a loss in high frequency fidelity such as localization, ambient information, and bright nature of audio. This paper provides a new mathematical analysis for the adaptive estimation of the high frequency contents based on the nature of the input low sample rate audio. Proposed method can be worked globally to any kind of audio such as speech and music that are restricted by sampling rate and bandwidth.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1036-1042
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• 2003

The hot embossing process has been mentioned as one of major nanoreplication techniques. This is due to its simple process, low cost, high replication fidelity and relatively high throughput. As the initial step of quantitating the embossing process , simple parametric study about embossing time have been carried out using high-resolution masters which patterned by the DRIE process and laser machining. Under the various embossing time, the viscous flow of thin PMMA films into microcavities during compression force has been investigated. Also, a study about simulating the viscous flow during embossing process has planned and continuum scale FDM analysis was applied on this simulation. With currently available test data and condition, simple FDM analysis using FLOW3D was made attempt to match simulation and experiment.

• Journal of computational fluids engineering
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• v.14 no.1
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• pp.53-61
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• 2009

The objective of this research is to design blade planform to reduce high speed impulsive(HSI) noise from a non-lifting helicopter rotor using CFD method and optimization techniques. As for the aero-acoustic analysis, CFD technique for aerodynamic analysis and Kirchhoff's method for the acoustic analysis were used. As for the optimization method, Kriging-based genetic algorithm(GA) model as a high-fidelity optimization method was chosen. Design variables and constraints are determined for arbitrary blade planform. The result shows that the optimized blade planform with high swept-back and taper ratio can reduce HSI noise by suppressing generation of the strong shock wave on blade surface and propagation of the noise to the farfield flow region.