• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.77-80
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• 2005

Local probe techniques such as scanning probe microscopy (SPM) or atomic force microscopy (AFM) extended our perception into ultra small world. Specially, the sense of touching was extended by AFM into the micro- and nanoworld and has provided complementary new insights of the microscopic world. In addition, touching objects is an essential step before trying to manipulate things. SPM as a touch sensor not only measure the mechanical properties but also detect different properties such as magnetic, electrical, ionic, thermal, chemical and biophysical properties in nanoscale and even less. Obtaining biophysical measurements, monitoring dynamics and processes together with high-resolution imaging of the biomolecules and cells with rather simpler sample preparation than any other techniques give great attractions to the scientists experimenting with biological samples. Among the many AFM capabilities we will specifically introduce the force plot which is used to measure tip-sample interactions and its application this time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.1004-1014
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• 2001

The fully automatic algorithm from initial finite element mesh generation to remeshing in two dimensional geometry is introduced using bubble packing method (BPM) for finite element analysis. BPM determines the node placement by force-balancing configuration of bubbles and the triangular meshes are made by Delaunay triangulation with advancing front concept. In BPM, we suggest two node-search algorithms and the adaptive/recursive bubble controls to search the optimal nodal position. To use the automatically generated mesh information in FEA, the new enhanced bandwidth minimization scheme with high efficiency in CPU time is developed. In the remeshing stage, the mesh refinement is incorporated by the control of bubble size using two parameters. And Superconvergent Patch Recovery (SPR) technique is used for error estimation. To verify the capability of this algorithm, we consider two elasticity problems, one is the bending problem of short cantilever beam and the tension problem of infinite plate with hole. The numerical results indicate that the algorithm by BPM is able to refine the mesh based on a posteriori error and control the mesh size easily by two parameters.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.487-492
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• 2009

This study was performed FE numerical analysis under 120-minute fire conditions, using the ABAQUS, a wide use software, on the basis of the test results by concrete tunnel lining fire strengths (ISO, RWS, and MHC). The concrete material test was to secure the material properties of concrete linings, which were numerical analysis input conditions. And then built the material properties, such as specific heat, heat transfer rate, heat expansion rate, density, elasticity coefficient and compression strength under high temperature conditions, as database at 20 $^{\circ}C$ to 800 $^{\circ}C$, applying them to analysis as input values. As a result, the tunnel linings under RWS fire conditions saw fire temperature rose to maximum 1119 $^{\circ}C$at the location of 5 mm above a thermal surface, and saw surface temperature amount to 1214 $^{\circ}C$ in the middle part.

• Journal of Fashion Business
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• v.10 no.6
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• pp.122-130
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• 2006

The purpose of this study is to develop the appropriate brassiere pattern for women. Total of 6 brands with same design and 75A, 80A size brassieres(total 12 brassieres) were compared and analyzed for pattern, cup size and patterns. SPSS 10.1 statistic process was used for data analysis. The outcom of this study is summarized as follows. Total length of brassiere by grade were performed smaller than the standard difference 5cm. For 1/2 front cover length, There were no significant differences between 75 and 80. The reason for lower line of wing is shorter than upper line of wing is because side support is cut side ways considering lower line of wing is sewn more toward front than upper line of wing. Even it is same A cup size most cup related sizes become larger according to underbust comparing with cup capacity, they range from 146.67cc to 172.83cc for same A cups. Among same A cups with difference underbust there was average of 26.16cc differences. For relations of material, sewing technology and expansion rate, all 6 brands had zigzag type sewing for upper line tape. For every 0.3cm height, there were $17{\sim}21$ stitches. When urethane mixture is similar expansion rate is higher while number of 1 inch zigzag are high. For elasticity, zigzag stitch expand side ways for more expansion.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.377-382
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• 2011

Poly(vinyl alcohol) (PVA) is an interesting material with good biocompatibility, high elasticity and hydrophilic chacrateristics. In this study, crosslinked hydrogels based on PVA, and poly(acrylic acid) (PAAc) were prepared by gamma-ray irradiation. PVA and PAAc powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make hydrogels. The hydrogels were then annealed in an oven at $120^{\circ}C$ for 10 min, 30 min and 50 min under nitrogen atmosphere. The properties of a hydrogel such as gel fraction, swelling behavior, thermogravimetric analysis (TGA) and adhesive strength as a function of PAAc content and annealing time were investigated. The gel fraction decreases with decreasing PAAc content and increasing annealing time. The thermal behaviors have shown different patterns according to the annealing time. The adhesive strength increases with increasing PAAc content.

• Biomaterials and Biomechanics in Bioengineering
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• v.4 no.1
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• pp.33-44
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• 2019

This paper presents a novel structural composition for artificial bone scaffolds with an appropriate biocompatibility and biodegradability capability. To achieve this aim, carbon nanotubes, due to their prominent mechanical properties, high biocompatibility with the body and its structural similarities with the natural bone structure are selected in component of the artificial bone structure. Also, according to the piezoelectric properties of natural bone tissue, the barium titanate, which is one of the biocompatible material with body and has piezoelectric property, is used to create self-healing ability. Furthermore, due to the fact that, most of the bone tissue is consists of hydroxyapatite, this material is also added to the artificial bone structure. Finally, polycaprolactone is used in synthetic bone composition as a proper substrate for bone growth and repair. To demonstrate, performance of the presented composition, the mechanical behaviour of the bone scaffold is simulated using ANSYS Workbench software and three dimensional finite element modelling. The obtained results are compared with mechanical behaviour of the natural bone and the previous bone scaffold compositions. The results indicated that, the modulus of elasticity, strength and toughness of the proposed composition of bone scaffold is very close to the natural bone behaviour with respect to the previous bone scaffold compositions and this composition can be employed as an appropriate replacement for bone implants.

• Wind and Structures
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• v.28 no.1
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• pp.49-62
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• 2019

In this paper, an analytical analysis for the study of vibratory behavior and wave propagation of functionally graded plates (FGM) is presented based on a high order shear deformation theory. The manufacture of these plates' defects can appear in the form of porosity. This latter can question and modify the global behavior of such plates. A new shape of the distribution of porosity according to the thickness of the plate was used. The field of displacement of this theory is present of indeterminate integral variables. The modulus of elasticity and the mass density of these plates are assumed to vary according to the thickness of the plate. Equations of motion are derived by the principle of minimization of energies. Analytical solutions of free vibration and wave propagation are obtained for FGM plates simply supported by integrating the analytic dispersion relation. Illustrative examples are given also to show the effects of variation of various parameters such as(porosity parameter, material graduation, thickness-length ratio, porosity distribution) on vibration and wave propagation of FGM plates.

• The Journal of Information Systems
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• v.30 no.3
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• pp.201-216
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• 2021

Purpose The purpose of this study is to analyze the trend of patent technology in textile materials using text mining methodology based on Dynamic Embedded Topic Model and Structural Topic Model. It is expected that this study will have positive impact on revitalizing and developing textile materials industry as finding out technology trends. Design/methodology/approach The data used in this study is 866 domestic patent text data in textile material from 1974 to 2020. In order to analyze technology trends from various aspect, Dynamic Embedded Topic Model and Structural Topic Model mechanism were used. The word embedding technique used in DETM is the GloVe technique. For Stable learning of topic modeling, amortized variational inference was performed based on the Recurrent Neural Network. Findings As a result of this analysis, it was found that 'manufacture' topics had the largest share among the six topics. Keyword trend analysis found the fact that natural and nanotechnology have recently been attracting attention. The metadata analysis results showed that manufacture technologies could have a high probability of patent registration in entire time series, but the analysis results in recent years showed that the trend of elasticity and safety technology is increasing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.85-91
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• 2022

The demand for electric vehicles has increased because of environmental regulations. The lithium-ion battery, the most widely used type of battery in electric vehicles, is composed of a cathode, an anode, and an electrolyte. It is manufactured according to the pole plate, assembly, and formation processes. To improve battery performance and increase manufacturing efficiency, the manufacturing process must be optimized. To do so, simulation can be used to reduce wasted resources and time, and a finite-element method can be utilized. For high simulation quality, it is essential to reflect the material properties of the electrode by considering the pores. However, the material properties of electrodes are difficult to derive through measurement. In this study, the representative volume element method, which is a homogenization method, was applied to estimate the representative material properties of the electrode considering the pores. The representative volume element method assumes that the strain energy before and after the conversion into a representative volume is conserved. The method can be converted into one representative property, even when nonhomogeneous materials are mixed in a unit volume. In this study, the material properties of the electrode considering the pores were derived. The results should be helpful in optimizing the electrode manufacturing process and related element technologies.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.505-513
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• 2022

Minor orthodontic treatment using a thin wire with high elasticity can shorten the treatment period and reduce the load on the anchorage by the application of light force. Since it can be applied immediately without a dental laboratory procedure and does not require the patient's cooperation, it can be clinically useful. The cases reported here have led to positive results in short periods of treatment, using only a segmented straight 0.012 inch NiTi wire and flowable resin to address various locations within the oral cavity, such as the anterior teeth, premolars, and molars.