• Particle and aerosol research
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• v.12 no.3
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• pp.73-80
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• 2016

Bioaerosol inactivation becomes important as people recognize the significance on the health effects of bioaerosols. There are several ways to inactivate such bioaerosols such as antimicrobial filters, UV, etc. For the on-filter-inactivation, proper antimicrobial materials coating should be applied. Recently, air ions are adopted to effectively reduce germ and virus activity. Limitations arise when each method is applied separately. Coating materials can experience chemical instability over time and temperature. Ionizers can generate ozone to prepare high ion concentrations. Combinations of developed techniques to enhance the inactivation efficiency were suggested. Researches on the air sterilization are reviewed and outlook is highlighted. Proper techniques such as combinations of filter material coating and air ion generation can be used to make air quality better for human living.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.65-70
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• 2003

The weight-of-evidence model one of the Bayesian probability model was applied to the task of evaluating landslide susceptibility using GIS. Using the location of the landslides and spatial database such as topography, soil, forest, geology, land use and lineament, the weight-of-evidence model was applied to calculate each factor's rating at Boun area in Korea where suffered substantial landslide damage fellowing heavy rain in 1998, The factors are slope, aspect and curvature from the topographic database, soil texture, soil material, soil drainage, soil effective thickness, and topographic type from the soil database, forest type, timber diameter, timber age and forest density from the forest map, lithology from the geological database, land use from Landsat TM satellite image and lineament from IRS satellite image. Tests of conditional independence were performed for the selection of the factors, allowing the 43 combinations of factors to be analyzed. For the analysis, the contrast value, W$\^$＋/and W$\^$-/, as each factor's rating, were overlaid to map laudslide susceptibility. The results of the analysis were validated using the observed landslide locations, and among the combinations, the combination of slope, curvature, topographic, timber diameter, geology and lineament show the best results. The results can be used for hazard prevention and planning land use and construction

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.1990-1995
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• 2012

This paper presents design methodology to determine the design parameters that affect the manufacture of aluminum forging piston using the FE simulation and the Taguchi method. Maximum forging load is used as the objective function, and preform, material temperature and draft angle are selected as the design parameters. Their combinations are implemented by orthogonal array, and forging load is evaluated through the simulation. From the analytic results of design parameters to minimize the load using signal to noise ratio, their optimal combinations are proposed. The proposed design methodology will be able to help in selecting proper preform among preforms and to be used in determining the optimal combination of the parameters in metal forming process.

• Journal of the Korean Wood Science and Technology
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• v.48 no.1
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• pp.22-31
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• 2020

In this study, rice straw and bagasse are used as raw materials to produce binderless particleboard (BPB). This study aims to evaluate the mechanical and physical properties of BPB. We identify the raw material that would be better for the production of BPB from the viewpoint of their basic properties. The BPBs are made from rice straw, bagasse, and combinations of both in ratios of 50:50 and 40:60, respectively. The modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) strength, water absorption, and thickness swelling properties of the different BPBs are determined and compared. Results showed that all the properties are significantly influenced by the type of particles or particle combinations in the BPB. BPBs made from bagasse alone have the highest MOR, MOE, and IB mean values, whereas BPBs made from rice straw alone exhibit the lowest MOR, MOE, and IB values. Meanwhile, BPBs made from a combination of rice straw and bagasse at 40:60 ratio by weight have the second highest values for properties such as MOR, MOE, and IB, followed by BPBs made from a combination of rice straw and bagasse at 50:50 ratio by weight.

• Structural Engineering and Mechanics
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• v.86 no.1
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• pp.69-83
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• 2023

Analytical solutions to problems are crucial because they provide high-quality comparison data for assessing the accuracy of numerical solutions. Benchmark analytical solutions for the vibrations of cracked functionally graded material (FGM) plates are not available in the literature because of the high level of complexity of such solutions. On the basis of first-order shear deformation plate theory (FSDT), this study proposes analytical series solutions for the vibrations of FGM rectangular plates with side or internal cracks parallel to an edge of the plates by using Fourier cosine series and the domain decomposition technique. The distributions of FGM properties along the thickness direction are assumed to follow a simple power law. The proposed analytical series solutions are validated by performing comprehensive convergence studies on the vibration frequencies of cracked square plates with various crack lengths and under various boundary condition combinations and by performing comparisons with published results based on various plate theories and the theory of three-dimensional elasticity. The results reveal that the proposed solutions are in excellent agreement with literature results obtained using the Ritz method on the basis of FSDT. The paper also presents tabulations of the first six nondimensional frequencies of cracked rectangular Al/Al2O3 FGM plates with various aspect ratios, thickness-to-width ratios, crack lengths, and FGM power law indices under six boundary condition combinations, the tabulated frequencies can serve as benchmark data for assessing the accuracy of numerical approaches based on FSDT.

• Structural Engineering and Mechanics
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• v.90 no.3
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• pp.287-299
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• 2024

Composite skew plates are aesthetically appealing light weight structural units finding wide applications in floors and roofs of commercial buildings. Although bending and vibration characteristics of these units have received attention from researchers but the domain of first and progressive failure has not been explored. Confident use of these plates necessitates comprehensive understanding of their failure behavior. With this objective, the present paper uses an eight noded isoparametric finite element together with von-Kármán's approach of nonlinear strains to study first ply and progressive failure up to ultimate damage of skew plates being subjected to uniform surface pressure. Parameters like skew angles, laminations and boundary conditions are varied and the results are practically analyzed. The novelty of the paper lies in the fact that the stiffness matrix of the damaged plate is calculated by considering material degradation locally only at failed points at each stage of first and progressive failure and as a result, the present outputs are so close to experimental findings. Interpretation of results from practical angles and proposing the relative performances of the different plate combinations in terms of ranks will be of much help to practicing engineers in selecting the best suited plate option among many combinations.

• KIEAE Journal
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• v.16 no.5
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• pp.73-79
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• 2016

Purpose: In order to improve the energy performance of existing buildings, so actively promoted green remodeling business. Also, improvement of the performance of envelope system of apartment housing is an absolute. The purpose of implementation of the data base and application plan of the envelope system for green remodeling of apartment housing. Method: For this study, It proposed a classification system of green remodeling envelope system constructed actual to select the applicable representative method and input material of apartment housing for green remodeling. In this study, divided into construction waste processing stage and production phase of the material for the boundary of the system, and implementation the classification system of the envelope system for applicable green remodeling. For this, established 6 environmental impact categories database. Result: As a result of various suggestions were available for case study research, alternative combinations of existing combinations than six kinds of environmental impact insulation system with superior input materials combining 96 kinds, window system, 12 kinds for determining the applicability of the established database. Depending on the account for a large proportion if compared to the detailed analysis of the environmental impact resulting from the production phase and disposal phase was analyzed that the operating management of the necessary input materials. Is considered that the economic performance and integrated energy performance required by the applicable public housing green remodeling evaluation techniques considered for future improvements insulation sheath.

• Land and Housing Review
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• v.11 no.2
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• pp.95-104
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• 2020

This study aims to explore a purely mechanistic pavement analysis approach where viscoelasticity and fracture of asphalt mixtures are considered to accurately predict deformation and damage behavior of flexible pavements. To do so, the viscoelastic and fracture properties of designated pavement materials are obtained through experiments and a fully mechanistic damage analysis is carried out using a finite element method (FEM). While modeling crack development can be done in various ways, this study uses the cohesive zone approach, which is a well-known fracture mechanics approach to efficiently model crack initiation and propagation. Different pavement configurations and traffic loads are considered based on three main functional classes of roads suggested by FHWA i.e., arterial, collector and local. For each road type, three different material combinations for asphalt concrete (AC) and base layers are considered to study damage behavior of pavement. A concept of the approach is presented and a case study where three different material combinations for AC and base layers are considered is exemplified to investigate progressive damage behavior of pavements when mixture properties and layer configurations were altered. Overall, it can be concluded that mechanistic pavement modeling attempted in this study could differentiate the performance of pavement sections due to varying design inputs. The promising results, although limited yet to be considered a fully practical method, infer that a few mixture tests can be integrated with the finite element modeling of the mixture tests and subsequent structural modeling of pavements to better design mixtures and pavements in a purely mechanistic manner.

• Clean Technology
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• v.15 no.1
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• pp.16-22
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• 2009

In this study, a fiber reinforced plastic (FRP) pipe with superior wear resistance was developed to replace the fly ash pipe of cast iron. Wear test was performed with various combinations of SiC filler and resin materials of unsaturated polyester, vinylester, epoxy, and phenol. Test results of ASTM D4060 showed the optimal combinations of resin, filler size, and resin/filler ratios. Test results of comparison between FRP and cast iron showed the possibility to replace cast iron pipe with the FRP pipe. Field test executed to compare the wear resistance between cast iron pipe and developed FRP pipe showed the superiority of the FRP pipe.

• Journal of Periodontal and Implant Science
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• v.53 no.3
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• pp.194-206
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• 2023

Purpose: A novel attachment system for implant-retained overdentures (IRODs) with novel material combinations for improved mechanical resilience and prosthodontic success (Novaloc) has been recently introduced as an alternative to an existing system (Locator). This study investigated whether differences between the Novaloc and Locator attachment systems translate into differences in implant survival, implant success, and patient-centered outcomes when applied in a real-world in-practice comparative setting in patients restored with mandibular IRODs supported by 2 interforaminal implants (2-IRODs). Methods: This prospective, intra-subject crossover comparison compared 20 patients who received 2 intra-foraminal bone level tapered implants restored with full acrylic overdentures using either the Locator or Novaloc attachment system. After 6 months of function, the attachment in the corresponding dentures was switched, and the definitive attachment system type was delivered based on the patient's preference after 12 months. For the definitive attachment system, implant survival was evaluated after 24 months. The primary outcomes of this study were oral health-related quality of life and patient preferences related to prosthetic and implant survival. Secondary outcomes included implant survival rate and success, prosthetic survival, perceived general health, and patient satisfaction. Results: Patient-centered outcomes and patient preferences between attachment systems were comparable, with relatively high overall patient satisfaction levels for both attachment systems. No difference in the prosthetic survival rate between study groups was detected. The implant survival rate over the follow-up period after 24 months in both groups was 100%. Conclusions: The results of this in-practice comparison indicate that both attachment systems represent comparable candidates for the prosthodontic retention of 2-IRODs. Both systems showed high rates of patient satisfaction and implant survival. The influence of material combinations of the retentive system on treatment outcomes between the tested systems remains inconclusive and requires further investigations.