• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.603-608
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• 2008

A simple equation to find a optimum speed of desiccant rotor is presented in this theoretical study. Usually the determination of optimum speed of desiccant rotor requires tedious and lengthy procedures by solving governing differential equations with many complicated parameters. The determining equation of optimal rotating speed is derivated from governing differential equations with three linearization assumptions, which simplify temperature profile linear along the desiccant rotor depth, psychrometric chart within a proper range, and relative humidity-sorption capacity relation. This study shows that the dominant parameters of optimal rotating speed of desiccant rotor are NTU, flow velocity, desiccant rotor depth, and temperature different between dehumidification and regeneration. The comparison shows the good agreement between complicated calculation results and simple theoretical equation prediction.

• Journal of computational fluids engineering
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• v.12 no.4
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• pp.38-43
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• 2007

Owing to the rapid progress in manufacturing technology of microscale devices, there are active research works in developing microscale propulsion systems. In this study, gas flows in nozzles with size of milli and sub-millimeter are investigated by using a CFD code based on the Navier-Stokes equations. The prediction results were compared with theoretical results of quasi-one-dimensional nozzle flow and experiment data. In general, theoretical values agree very well with the CFD results. However, theoretical values begin to deviate from the CFD and experimental data for relatively small Reynolds numbers and the nozzle shape with rectangular cross section. The primary reason for this discrepancy is due to the existence of the thick boundary layer at the wall in low Reynolds flows.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.28-38
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• 1990

The study is concerned with the theoretical and experimental investigation of axisymmetric fluid pressure-driven hydroforming of sheet metal by forming over the die cavity. The rigid-plastic finite element method is employed to calculate the stress and strain distribution. The effect of blank size and die radius is also studied in the finite element analysis. Experiments are carried out for hydroforming of cold-rolled steel sheets under various process conditions. The computational results are compared with the experimental results for the forming pressure vs. pole displacement relations and strain distributions. Comparison has shown that theoretical predictions by the finite element method are in good agreement with the experiment with the experimental observations. Thus, it is shown that the rigid-plastic finite element method is effectively used in the analysis of axisymmetric fluid pressure-driven hydroforming process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.336-345
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• 1996

A theoretical and experimental study was conducted in order to design highly efficient solar air heaters using porous material. Radiative characteristics of glass windows and porous absorbing media were correlated through spectral transmittances measured by the UV-Visible and the FT-IR spectrometers. Using those characteristics the efficiencies of collectors were numerically calculated with the use of the two-flux radiation model. Based on the theoretical results, an experimental solar collector was designed and constructed. Experimental results under various conditions show that the daily efficiencies are over 60% in general and agree well with the theoretically calculated ones.

• Journal of ILASS-Korea
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• v.26 no.1
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• pp.26-32
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• 2021

In this study, the thickness of the liquid sheet formed by two low speed impinging jets was measured by the direct contact method. The effects of jet velocity and liquid viscosity on the thickness were analyzed and the results were compared with theoretical modeling and optical thickness measurement results. The liquid film thickness decreased as the radius and circumferential angle increased. The jet velocity did not affect the liquid film thickness as predicted in theoretical modeling. In the theoretical modeling, there was no influence of the fluid properties on thickness, but in the case of low viscosity liquids, the thickness was predicted high, and it was well matched in high viscosity liquids. The direct measurement results showed no significant difference from the optical measurement results, thus confirming the reliability of the optical measurement method.

• Geomechanics and Engineering
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• v.30 no.4
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• pp.337-343
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• 2022

The electrical resistivity method is a well-known geophysical method for observing underground conditions, (such as anomalies) and the properties of soil and rock (such as porosity, saturation, and pore fluid characteristics). The shape of electrodes used in an electrical resistivity survey depends on the purpose of the survey and installation conditions. Most electrodes for field applications are cylindrical for sufficient contact with the ground, while some are conically sharpened at their tips for convenient penetration. Previous study only derived theoretical equations for rod-shaped electrodes with spherical tips. In this study, the theoretical resistance for two cylindrical electrodes with conical tips is derived and verified experimentally. The influence of the penetration depth and tip on the measurement is also discussed.

• Corrosion Science and Technology
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• v.21 no.1
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• pp.21-31
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• 2022

Potentiodynamic polarization, EIS measurements, quantum chemical calculations, and molecular dynamic simulations were used to investigate the corrosion behavior of mild steel in 0.5 M aqueous hydrochloric acid medium in the presence or absence of nystatin drug. Potentiodynamic tests suggested that this molecule could act as a mixed inhibitor due to its adsorption on the mild steel surface. The objective of this study was to exploit theoretical calculations to gain a better understanding mechanism of inhibition. Calculating the adsorption behavior of the investigated molecule on Fe (1 1 0) surface was accomplished using Monte Carlo simulation. Molecules were also investigated using Density Functional Theory (DFT), specifically PBE functional, in order to identify the link between molecular structure and corrosion inhibition behavior of the compound under investigation. Adsorption energies between nystatin and iron were estimated more accurately by utilizing Molecular Mechanics calculation with Periodic Boundary Conditions (PBC). Estimated theoretical parameters significantly assisted our understanding of the corrosion inhibition mechanism exhibited by this molecule. They were found to be in accord with experimental results.

• Educational Technology International
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• v.16 no.2
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• pp.249-272
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• 2015

This study is a theoretical exploration of project-based service-learning and its application in designing pre-dental curricula. As a response to the limitation of community service courses, service-learning has been implemented as pedagogy in higher education practices. Service-learning connects service and learning by engaging students in activities that address community needs with intentionally designed learning opportunities while adding value to and transforming both service and learning. Project-based service-learning is an extended and more active version of service-learning. Whereas service activities are arranged by instructors in the original service-learning, project-based service-learning provides students with opportunities for exploring problems and root causes on site and then devising and implementing solutions of their own using their talents and creativity. This study proposes a theoretical approach to project-based service-learning and suggests six design components, namely, related curriculum, reflection, reciprocity, service and community engagement, evaluation and recognition, and creative problem solving. Based on the components, 20 design strategies are formulated. The exploration is aimed to provide design guides for professionals attempting to implement project-based service-learning in higher education.

• Journal of architectural history
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• v.33 no.2
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• pp.29-39
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• 2024

In contemporary architectural discourse, the concept of space is ubiquitous, yet its historical genesis and theoretical underpinnings in Gottfried Semper's seminal theoretical work remain under explored. This study investigates the reception and integration of Semper's architectural theory into modern discourse, tracing its trajectory from August Schmarsow, to Nikolaus Pevsner, to Sigfried Giedion. While Semper's "cladding theory" had initially been understood in terms of both its relation to physical properties and structural and functional values, leading to an expansion of cladding as a new genre of art, i.e. arts and crafts, Semper's "architectural theory" instead explained cladding theory in terms of space. In disseminating Semper's theoretical work, Schmarsow was especially important as he himself played an increasingly prominent role in expanding the boundaries of modernist architectural theory and practice from the beginning of the 20th century on.

• Korean Journal of Social Welfare
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• v.59 no.2
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• pp.39-64
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• 2007

The purpose of this study is to find out implications which can be useful for the development of user empowerment and involvement in Korean disability services. Suggested implications are based on the earlier studies about the concept and areas of user involvement. In the theoretical review, this study compared several terminologies related to user involvement. For the depth explanation, this study described wide range of earlier studies. In addition to these descriptions, this study is exploring to show integrated theoretical framework including diverse areas, major initiatives, participation levels, models of purpose on user involvement. And to grasp ostensive understanding on specific mechanisms on participation practice, this study discussed various issues on basic assumptions, areas of involvement and supportive alternatives. Based on these theoretical examination, this study introduced concrete tasks related to policy, service organization, professional education and research to activate user participation in Korean disability services.