• Korean Institute of Interior Design Journal
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• v.23 no.4
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• pp.32-41
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• 2014

The purpose of this study is providing a systematic method of exterior, interior finish materials and color scheme for elementary school and the actual color plans of elementary schools in Busan was analyzed to support the study. As a powerful design tool, a finish materials and a color are very effective to alter the perception of a building and a view. Most of the school, a shape and a material of elevations are monotonous and uniform and it makes students are hard to attach to their schools. As a place for learning and school life, the inner space of elementary classroom needs to be considered very important. The new basic guideline for developing and planning of architectural design could be achieved by researching a current plan and a finish material in elementary school. As a result, this study will benefit in planning both the exterior and interior environments of color.

• Steel and Composite Structures
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• v.11 no.4
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• pp.341-358
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• 2011

This paper presents the effects of thermal environment and temperature-dependence of the material properties on axisymmetric bending of functionally graded (FG) circular and annular plates. The material properties are assumed to be temperature-dependent and graded in the thickness direction. In order to accurately evaluate the effect of thermal environment, the initial thermal stresses are obtained by solving the thermoelastic equilibrium equations. Governing equations and the related boundary conditions, which include the effects of initial thermal stresses, are derived using the virtual work principle based on the elasticity theory. The differential quadrature method (DQM) as an efficient and robust numerical tool is used to obtain the initial thermal stresses and response of the plate. Comparison studies with some available results for FG plates are performed. The influences of temperature rise, temperature-dependence of material properties, material graded index and different geometrical parameters are carried out.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.448-451
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• 2005

It was observed that after unloading or removal of the load from the specimen subjected to bending stress, partial or full elastic spring back occurred and considerable stresses have resulted while plastic deformation was considered. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, it was used as the main tool to analyze elastic and plastic deformations of hi-material metal joint. In the case of elastic deformations, the results were comparable to the theoretical data. Plastic deformations and residual stresses of hi-material metal joint under bending moment were obtained by ABAQUS; where the theory needs to be studied and improved further to verify the results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.2
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• pp.143-148
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• 2004

This paper discussed on the stability of elastic material subjected to dry friction force for low boundary conditions: clamped free, clamped-simply supported, simply supported-simply supported, clamped-clamped. It is assumed in this paper that the dry frictional force between a tool stand and an elastic material can be modeled as a distributed follower force. The friction material is modeled for simplicity into a Winkler-type elastic foundation. The stability of beams on the elastic foundation subjected to distribute follower force is formulated by using finite element method to have a standard eigenvalue problem. It is found that the clamped-free beam loses its stability in the flutter type instability, the simply supported-simply supported beam loses its stability in the divergence type instability and the other two boundary conditions the beams lose their stability in the divergence-flutter type instability.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.155-160
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• 2018

The materials used for 3D printing are mainly plastic and metal. These materials are usually used in the powdered form. In order to improve the surface roughness of a manufactured product, these powders should consist of small uniform spherical particles. However, the powdered forms are sold at a considerably higher price than bulk or wired materials. When a wire-type material is used instead of a powder, we can supply a relatively large amount of the material at one time as well as reduce the cost. Moreover, the use of this form of the material will increase the process efficiency. This paper deals with the technology required to feed a wire material in front of the tool movement and discusses the examples used for the verification.

• Progress in Superconductivity
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• v.6 no.1
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• pp.1-6
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• 2004

Melt-textured YBCO in high quantity and good quality is prepared in a batch process. A mean trapped field >1. IT at 77K is achieved in batch processed material. Studying the microstructure is a necessary tool to understand the growth mechanisms and thus to opimise the material. From the growth induced structures in the material the anisotropy in growth speed is 1.37. From batch processed material function elements for different cryomagnetic applications are constructed. Motors with an output power > 200 kW at 77 K and bearings that can lift more than 200 kg were equipped with melt-textured YBCO.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.120-130
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• 1993

Generally, the machinability of materials that have a good mechanical properties is poor. For materials having a high strength, high toughness, high strength in high temperature and wear resistance, it is difficult to remove a chip from work materials. These properties are well shown in a Nickel, so this metal is used in machine materials, semi-conductor industry, metal mold and optical fields etc. But it is limitted in use because of high cost and poor machinability. In this study, the cutting of pure Nickel was conducted to examine wear of CBN, poly crystal diamond (PCD) and single crystal diamond (SCD) tools. From the result, the CBN tool is superior to poly crystal diamond tools or single crystal diamond tools in terms of tool wear and tool wear is predictable from experimental data base.

• Design & Manufacturing
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• v.16 no.4
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• pp.1-6
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• 2022

Fine blanking is a press processing technology that can process most of the product thickness into a smooth surface with a single stroke. In this fine blanking process, shear is an essential step. The punches and dies used in the shear are subjected to impacts of tens to hundreds of gravitational accelerations, depending on the type and thickness of the material. Therefore, among the components of the fine blanking mold (dies), punches and dies are the parts with the shortest lifespan. In the actual production site, various types of tool damage occur such as wear of the tool as well as sudden punch breakage. In this study, machine learning algorithms were used to predict these problems in advance. The dataset used in this paper consisted of the signal of the vibration sensor installed in the tool and the measured burr size (tool wear). Various features were extracted so that artificial intelligence can learn effectively from signals. It was trained with 5 features with excellent distinguishing performance, and the SVM algorithm performance was the best among 33 learning models. As a result of the research, the vibration signal at the time of imminent tool replacement was matched with an accuracy of more than 85%. It is expected that the results of this research will solve problems such as tool damage due to accidental punch breakage at the production site, and increase in maintenance costs due to prediction errors in punch exchange cycles due to wear.

• Safety and Health at Work
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• v.15 no.2
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• pp.192-199
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• 2024

Background: Safety data sheets (SDSs) are hazard communication materials that accompany chemicals/hazardous products in the workplace. Many SDSs contain dense, technical text, which places considerable comprehension demands on workers, especially those with lower literacy skills. The goal of this study was to assess SDSs for readability, comprehensibility, and suitability (i.e., fit to the target audience). Methods: The Suitability Assessment of Materials (SAM) tool assessed SDSs for suitability and readability. We then amended the SAM tool to further assess SDSs for comprehensibility factors. Both the original and amended SAM tool were used to score 45 randomly selected SDSs for content, literacy demand, graphics, and layout/typography. Results: SDSs performed poorly in terms of readability, suitability, and comprehensibility. The mean readability scores were Flesch-Kincaid Grade Level (9.6), Gunning Fog index (11.0), Coleman-Liau index (13.7), and Simple Measure of Gobbledygook index (10.7), all above the recommended reading level. The original SAM graded SDSs as "not suitable" for suitability and readability. When the amended SAM was used, the mean total SAM score increased, but the SDSs were still considered "not suitable" when adding comprehensibility considerations. The amended SAM tool better identified content-related issues specific to SDSs that make it difficult for a reader to understand the material. Conclusions: In terms of readability, comprehensibility, and suitability, SDSs perform poorly in their primary role as a hazard communication tool, therefore, putting workers at risk. The amended SAM tool could be used when writing SDSs to ensure that the information is more easily understandable for all audiences.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.501-509
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• 2013

To evaluate the development of the microstructure and mechanical properties on surface modified and post-heattreated Inconel 718 alloy, this study was carried out. A friction stir process as a surface modification method was employed, and overlap welded Inconel 718 alloy as an experimental material was selected. The friction stir process was carried out at a tool rotation speed of 200 rpm and tool down force of 19.6-39.2 kN; post-heat-treatment with two steps was carried out at $720^{\circ}C$ for 8 h and $620^{\circ}C$ for 6 h in vacuum. To prevent the surface oxidation of the specimen, the method of using argon gas as shielding was utilized during the friction stir process. As a result, applying the friction stir process was effective to develop the grain refinement accompanied by dynamic recrystallization, which resulted in enhanced mechanical properties as compared to the overlap welded material. Furthermore, the post-heat-treatment after the friction stir process accelerated the formation of precipitates, such as gamma prime (${\gamma}^{\prime}$) and MC carbides, which led to the significant improvement of mechanical properties. Consequently, the microhardness, yield, and tensile strengths of the post-heat-treated material were increased more than 110%, 124% and 85 %, respectively, relative to the overlap welded material. This study systematically examined the relationship between precipitates and mechanical properties.