• Earthquakes and Structures
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• v.14 no.5
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• pp.411-424
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• 2018

This study explores the inelastic behavior of systems with flexible base. The use of a single degree of freedom system (ESDOF) with equivalent ductility to represent the response of flexible base systems is discussed. Two different equations to compute equivalent ductility are proposed, one which includes the contribution of rigid body components, and other based on the overstrength of the structure. In order to asses the accuracy of ESDOF approach with the proposed equations, the behavior of a 10-story regular building with reinforced concrete (RC) moment resisting frames is studied. Local and global ductility capacity and demands are used to study the modifications introduced by base flexibility. Three soil types are considered with shear wave velocities of 70, 100 and 250 m/s. Soil-foundation stiffness is included with a set of springs on the base (impedance functions). Capacity curves of the building are computed with pushover analysis. In addition, non linear time history analysis are used to asses the ductility demands. Results show that ductility capacity of the soil-structure system including rigid body components is reduced. Base flexibility does not modify neither yield and maximum base shear. Equivalent ductility estimated with the proposed equations is fits better the results of the numerical model than the one considering elastoplastic behavior. Modification of beams ductility demand due to base flexibility are not constant within the structure. Some elements experience reduced ductility demands while other elements experience increments when flexible base is considered. Soil structure interaction produces changes in the relation between yield strength reduction factor and structure ductility demand. These changes are dependent on the spectral shape and the period of the system with fixed and flexible base.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.5
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• pp.387-392
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• 2017

There is a constant demand for hull variation related to ship design. Various input variables are generally given to achieve the objective functions assigned by each variation process. When dealing with geometric shapes accompanied by nonlinear operations during the variation process, vague relationships or uncertainties among input variables are commonly observed. Therefore, it is strongly recommended to identify those uncertainty factors in advance. A method to modify the shape of a closed hull form with a new area and a centroid had been introduced as a new process of hull variation. Since uncertainty between input variables still existed in the method, however, it was not easy for the user to enter the area and the corresponding centroid. To overcome this problem, a method is presented in this paper to provide the feasible region of centroids for a given area. By utilizing the concept and techniques used in the statistics such as the number of samples, probability, margin error, and level of confidence, this method generates the distribution of possible centroids along the regression curve. The result shows that the method helps the user to choose an appropriate input value following his or her design intention.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.743-749
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• 2015

In this paper, we describe the dynamic tumble-stability analysis of a seabed-walking robot named Crabster (CR200) in forward-incident currents. CR200 is designed to be operated in tidal-current conditions, and its body shape is also designed to minimize hydrodynamic resistances considering hydrodynamics. To analyze its tumble stability, we adopt the dynamic stability margin of a ground-legged robot and modify the definition of the margin to consider tidal-current effects. To analyze its dynamic tumble stability, we use the estimated hydrodynamic forces that act on the robot in various tidal-current conditions, and analyze the dynamic tumble-stability margin of the robot using the estimated results obtained for the various tidal-current conditions. From the analyses, we confirm the improved tumble stability of the robot according to the movement of the tumble axis caused by the supporting points of the legs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.694-699
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• 2002

As the demand for slim laptops requires ion'-height optical disc drives, vibration problems of optical disc drives are of great concern. Additionally, with the decrease of a track width and a depth of focus in high density drives, studies on vibration resonance between mechanical parts become more important. From the vibration point of view, the performance of optical disc drives is closely related with the relative displacement between a disc and an objective lens which is controlled by servo mechanism. In other words, to read and write data properly, the relative displacement between an optical disc and an objective lens should be within a certain limit. The relative displacement is dependent on not only an anti-vibration mechanism design but also servo control capability. Good servo controls can make compensation for poor mechanisms, and vice versa. In a usual development process, robustness of the anti-vibration mechanism is always verified with the servo control of an objective lens. Engineers partially modify servo gain margin in case of a data reading error. This modification cannot correct the data reading error occasionally and the mechanism should be redesigned more robustly. Therefore it is necessary to verify a mechanism with respect to the possible servo gain plot. In this study we propose the experimental verification method far anti-vibration mechanism with respect to the existing servo gain plot. This method verifies axial vibration characteristics of optical disc drives on the basis of transmissibility. Using this method, we verified our mechanism and modified the mechanism for better anti-vibration characteristics.

• Journal of Fashion Business
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• v.24 no.4
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• pp.130-143
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• 2020

The development of three-dimensional (3D) printing technology is bringing new innovations to various fields such as health care, architecture, and fashion. 3D printing can be manufactured to suit the size of the consumer's body, modify the design to meet their tastes, and produce small quantities of various products. Therefore, 3D printing in the field of fashion has great potential. The purpose of this study was to investigate various application models of 3D printing for fashion design and analyze their characteristics after developing the fashion garment samples. First, the background of 3D printing was reviewed then, fashion designed by a 3D printing application was analyzed. As a result, four types of 3D printing applications were developed: object-attached, linkage, kinematics, and assembly. The object-attached type was the method of printing 3D material as an object in the intended shape and form and was attached to the garment by sewing. The linkage type referred to printing 3D material in small pieces of certain shapes that could be linked. The kinematics type was structures with hinges that could flex to fit the human body. The assembly type referred to developing 3D materials in female and male pieces such as nuts and bolts. By providing the advantages, disadvantages, trial-and-errors, and challenges of the 3D printing fashion design process, this study contributes to the effective applications and possibilities of future design.

• Journal of the Korean Society of Costume
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• v.56 no.9 s.109
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• pp.66-82
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• 2006

Clothes and human body are inseparably related. Aesthetic consciousness of the body determines the form of clothing, reflecting the time and culture as well as the individual and society. Clothes can even reorganize the meaning of the body, while transcending their instrumental functions of protecting, expanding and deforming the body. Using 'body' to analyze the clothing form, my study develops a framework by which to classify the representation of the body in fashion focusing on the representation of physicality. In order to inquire the formative style and aesthetic values expressed in representing body in fashion, my study examines subjects from the 14th century European costumes to fashion collections of the 20th century. In fashion, representation of the body is visually analogous to the ideal boily shape and structure, including a realistic presentation of the body as well as reflection of aesthetic ideals. Manipulation of physicality entails the reconstruction of the ideal body image through the clothes that modify physicality into unnatural body. Ruff collar, gigot sleeve, crinoline, bustle, stomacher, and corset were all used to materialize the fictitious curves symbolizing femininity, authority, healthiness, maternity, virginity, socioeconomic status, and fertility. Accentuating specific clothing parts represents emphasizing the symbolism of the correspondent body parts. Consequently, in this phase signifiant is $signifi\'{e}$. Aesthetic ideal of the body is visualized in the firm of a dress. Fashion continues to explore forms and images that transcend the traditional representations of the clothed body. As a type of intimate architecture, fashion always mediates the dialogue between clothes and body, or fashion and figure. My study suggests a framework to analyze bodily representation in fashion, focusing on the relationship between the clothes and body.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.599-612
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• 1998

Numerical analysis of convection-dominated transport problems are challenging because of dual characteristics of the governing equation. In the finite element method, a strategy is to modify the test function to weight more in the upwind direction. This is called as the Petrov-Galerkin method. In this paper, both N+1 and N+2 Petrov-Galerkin methods are applied to transport problems at high grid Peclet number. Frequency fitting algorithm is used to obtain optimal levels of N+2 upwinding, and the results are discussed. Also, a new Petrov-Galerkin method, named as "Optimal Test Function Petrov-Galerkin Method," is proposed in this paper. The test function of this numerical method changes its shape depending upon relative strength of the convection to the diffusion. A numerical experiment is carried out to demonstrate the performance of the proposed method.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.1
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• pp.1-14
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• 2018

In this study, we develop and propose damping correction factors for the Korean standard design spectra. The newly proposed Korean standard design spectra has been given only for 5% damping ratio. But in practice, engineers need design spectra for damping values other than 5%. To obtain design spectra for various damping values from the standard spectra, damping correction factors are derived. These factors modify the shape of design spectra in accordance with the damping ratio. Response spectra for various damping values are calculated from the earthquake records that had been used to calculate standard design spectra. They consist of 55 records from 18 earthquakes occurred in overseas intraplate regions and Korea. The regressed spectra for the damping values ranging from 0.5% to 50 % are compared with standard spectra at three regions acceleration, velocity and displacement sensitive regions. The regression analysis of these data rendered formula for damping correction factors. Finally, a single formula for damping correction factors is recommended that is valid for both horizontal and vertical design spectra and that is applicable to the entire range of periods. One thing to note that recommended damping correction factors is valid for the design spectrum of the rock grounds because the design spectra was developed based on the earthquake records of the rock ground.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.581-588
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• 2020

Reducing CO₂ into high value fuels and chemicals is considered a great challenge in the 21st century. Efficiently activating CO₂ will lead to an important way to utilize it as a resource. This article reviews the latest progress of g-C₃N₄ based catalysts for CO₂ reduction. The different synthetic methods of g-C₃N₄ are briefly discussed. Article mainly introduces methods of g-C₃N₄ shape control, element doping, and use of oxide compounds to modify g-C₃N₄. Modified g-C₃N₄ has more reactive sites, which can significantly reduce the probability of photogenerated electron hole recombination and improve the performance of photocatalytic CO₂ reduction. Considering the literature, the hydrothermal method is widely used because of its simple equipment and process and easy control of reaction conditions. It is foreseeable that hydrothermal technology will continue to innovate and usher in a new period of development. Finally, the prospect of a future reduction of CO₂ by g-C₃N₄-based catalysts is predicted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.1
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• pp.1-4
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• 2002

A short shot is a molded part that is incomplete because insufficient material was injected into the mold. Any factors that increase the resistance of polymer melt to flow or prohibit delivery of sufficient material into the cavity can cause a short shot. Inappropriate injection pressure is one of the most common factors which cause a short shot. Conventionally, domain experts in injection molding decide and modify the pressure based on their experience. It is difficult for a non-expert to decide the pressure properly with the considerations such as a part dimension, shape, and other processing variables. In this study, fuzzy algorithm is proposed to standardize the empirical determination of the pressure so that not only the experts but also non-experts can find the appropriate injection pressure easily. To acquire the more accurate results. domain experts should be interviewed and then technical documents which are collected from the experts should be restored in the fuzzy rule base. But in this study, simulations have been done by using C-MOLD to settle the rule base because it takes much time and also it's difficult to meet and interview the experts.