• Steel and Composite Structures
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• v.32 no.3
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• pp.293-304
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• 2019

In the present paper, the element free Galerkin (EFG) method is developed for geometrically nonlinear analysis of deep beams considering small scale effect. To interpret the behavior of structure at the nano scale, the higher-order gradient elasticity nonlocal theory is taken into account. The radial point interpolation method with high order of continuity is used to construct the shape functions. The nonlinear equation of motion is derived using the principle of the minimization of total potential energy based on total Lagrangian approach. The Newmark method with the small time steps is used to solve the time dependent equations. At each time step, the iterative Newton-Raphson technique is applied to minimize the residential forces caused by the nonlinearity of the equations. The effects of nonlocal parameter and aspect ratio on stiffness and dynamic parameters are discussed by numerical examples. This paper furnishes a ground to develop the EFG method for large deformation analysis of structures considering small scale effects.

• Korean Journal of Human Ecology
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• v.4 no.1
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• pp.63-74
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• 1995

Urben wage workers' education expenditure among different social classes from 1979 to 1993 has been compared. Eduction expenditure has increased much more than that of income resulting from income increase and government policy. Education expenditure gaps among social classes have showed to be an increasing trend although the ratio of education expense to the income has increased among low class families. Average income elasticity was 1.1 and this result showed that education expense was luxury good. Income elasticity of education expense among low class families have fluctuated more than any other classes resulting from construction business cycle and housing rent increase. Average Gini coefficient was 0.38 and turned out to be highest among 9 household expenditures, however it was in the trend of improvement from 81. But from 91 Gini Coefficient went up high again. Main reason for this increase was due to high social class families' eucation expenditure increase. Government's strong policies to enhance equality level of education opportunity and to support low class families are urged.

• Journal of Fashion Business
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• v.24 no.6
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• pp.120-134
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• 2020

Recently, the beauty industry has implemented personalized services based on skin big data. To increase competitiveness in the beauty industry, systematic data measurement and evaluation indicators are necessary to select data and obtain necessary knowledge. In response, this study sought to stably enhance the accuracy of skin diagnosis based on satisfaction and reliability. To this end, the research was conducted through focus group interviews (FGI), a case study of brands, and analysis of prior research results. In particular, as a result of analyzing keywords that classify skin types by brand, common survey items for skin types were oiliness and using moisturizer, cosmetic use and vascular of skin, external stimulus and blemish & freckles, facial wrinkle, outside activities, self-consciousness, and smoke. In additioin to the common questions of the preceding study and the brand survey items, the questions concerning complex skin types, seasonal change, facial color, wrinkles and elasticity were added, and the questions were presented in a total of 40 items. In particular, it suggested that skin measurement could be conducted by focusing on elasticity and pigmentation items by reflecting the results of prior research and the opinions of FGI, and based on this, a customized service with high satisfaction and high accuracy of beauty care based on this could be proposed. We hope that this study will facilitate active self-care by providing more satisfying skin stones and personalized cosmetics proposals, thus laying the foundation for the further development of the cosmetics industry.

• Structural Engineering and Mechanics
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• v.85 no.1
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• pp.29-53
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• 2023

High-strength shielding concrete against gamma radiation is a priority for many medical and industrial facilities. This paper aimed to investigate the gamma-ray shielding properties of high-strength hematite concrete mixed with silica fume (SF) with nanoparticles of lead dioxide (PbO₂), tungsten oxide (WO₃), and bismuth oxide (Bi₂O₃). The effect of mixing steel fibres with the aforementioned binders was also investigated. The reference mixture was prepared for high-strength concrete (HSCC) containing 100% hematite coarse and fine aggregate. Thirteen mixtures containing 5% SF and nanoparticles of PbO₂, WO₃, and Bi₂O₃ (2%, 5%, and 7% of the cement mass, respectively) were prepared. Steel fibres were added at a volume ratio of 0.28% of the volume of concrete with 5% of nanoparticles. The slump test was conducted to workability of fresh concrete Unit weight water permeability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity tests were conducted to assess concrete's engineering properties at 28 days. Gamma-ray radiation of 137Cs emits photons with an energy of 662 keV, and that of 60Co emits two photons with energies of 1173 and 1332 keV were applied on concrete specimens to assess radiation shielding properties. Nanoparticles partially replacing cement reduced slump in workability of fresh concrete. The compressive strength of mixtures, including nanoparticles was shown to be greater, achieving 94.5 MPa for the mixture consisting of 7.5 PbO2. In contrast, the mixture (5PbO₂-F) containing steel fibres achieved the highest values for splitting tensile, flexural strength, and modulus of elasticity (11.71, 15.97, and 42,840 MPa, respectively). High-strength shielded concrete (7.5PbO2) showed the best radiation protection. It also showed the minimum concrete thickness required to prevent the transmission of radiation.

• The Journal of the Acoustical Society of Korea
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• v.29 no.3E
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• pp.107-110
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• 2010

In this paper, the rationale and contents of the special issue of the Journal of the Acoustical Society of Korea regarding comprehensive reviews on past, present and future of biomedical ultrasound are described. Brief descriptions of invited articles are given, and efforts by all contributing authors are gratefully acknowledged.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.152-152
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• 2004

카본나노튜브(Carbon Nanotube)는 다른 물질과 구별되는 날카로움(Sharpness), 고세장비(High Aspect Ratio), 높은 기계적 강성(Stiffness), 고탄성(high Elasticity), 그리고 반도체(semi-conducting)와 도체(Metallic) 성질 때문에, 카본나노튜브는 많은 연구에 적용되고 있으며, 카본나노튜브가 부착된 AFM(Atomic Force Microscope) 팁을 이용한 AFM 측정은 CNT 응용에 있어서 매우 큰 효과를 내는 응용분야 중 하나이다. AEM 팁에 카본나노튜브를 붙이는 이전 연구는 대부분 화학증착법(Chemical Vapor Deposition)에 의해 이루어 졌으며, 매우 효과적인 방법이지만 고가의 장비와 고온의 챔버내에서 이루어진다는 문제점을 가지고 있다.(중략)

• Advances in Computational Design
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• v.9 no.1
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• pp.53-71
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• 2024

Owing to these mechanical properties, carbon nanotubes have the potential to be employed in many future devices and nanostructured materials. As an example, high Young modulus accompanied by their low density, makes them a good choice for reinforcing material in composites. Therefore, we empathize and manually derive the results which shows the utilized lemma and criterion are believed effective and efficient for aircraft structural analysis of composite and nonlinear scenarios. To be fair, the experiment by numerical computation and calculations were explained the perfectness of the methodology we provided in the research.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.213-222
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• 1996

This paper presents the improved elastic modulus equation more appropriate to predict the modulus of elasticity of structural elements designed and made by high- and ultra high-strength concrete under domestic situation in Korea. To justify and assess the proposed elastic modulus equation, more than 400 laboratory test data domestically available in the literature and having the range of 400 to 1.000kg/$\textrm{cm}^2$ in concrete compressive strength were collected and analyzed statistically. Comparison of the proposed elastic modulus equation with the previously suggested equations in the ACI363R. CEB-FIP, NS3473 and New-RC were also presented to demonstrate the applicability to practice.

• Advances in concrete construction
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• v.1 no.2
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• pp.151-162
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• 2013

The performance characteristics of high-strength and high-performance concrete are discussed in this review. Recent developments in the field of high-performance concrete marked a giant step forward in high-tech construction materials with enhanced durability, high compressive strength and high modulus of elasticity particularly for industrial applications. There is a growing awareness that specifications requiring high compressive strength make sense only when there are specific strength design advantages. HPC today employs blended cements that include silica fume, fly ash and ground granulated blast-furnace slag. In typical formulations, these cementitious materials can exceed 25% of the total cement by weight. Silica fume contributes to strength and durability; and fly ash and slag cement to better finish, decreased permeability, and increased resistance to chemical attack. The influences of various mineral admixtures such as fly ash, silica fume, micro silica, slag etc. on the performance of high-strength concrete are discussed.

• Science of Emotion and Sensibility
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• v.12 no.1
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• pp.77-86
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• 2009

A comfort evaluation of car seat clothing has been proposed for high comforts interior seat clothing. Car seat covers have received wide spread attention due to their man-machine interface working. And then, it will be necessary for measurements on delicate basic mechanical-properties, which closely relate with human touch feeling of its materials. In this research, we have utilized $KES-FB^{(R)}$(Kawabata Evaluation System) series, $^ST300{(R)}$ analogue softness tester and friction tester for measurement a physical properties. In order to consider both kansei and physical properties on interior seat covers, we firstly have established subjective words of judgement for the seat covers. Secondly, related them to the objective measurement of physical properties. Each kansei-language has clearly defined as 'Softness', 'Elasticity', 'Volume' and 'Stickiness' for the adjectives of leather car seat covers. These technical terms have correlated to physical properties in other words, h (mm), bending moment ($gf^*$cm/cm), To-Tm (mm) and ${\mu}$. At this time, fuzzy logic has utilized to predict the value of kansei language through physical values. On the basis of this result, finally it is possible to predict quality index of car seat covers using neural networks technique. In short, we develop a quality evaluation system of car seat clothing combining four physical quantities with kansei engineering.