• Smart Structures and Systems
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• v.15 no.6
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• pp.1521-1542
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• 2015

The use of shape memory alloys (SMAs) in dynamical systems has an increasing importance in engineering especially due to their capacity to provide vibration reductions. In this regard, experimental tests are essential in order to show all potentialities of this kind of systems. In this work, SMA springs are incorporated in a dynamical system that consists of a one degree of freedom oscillator connected to a linear spring and a mass, which is also connected to the SMA spring. Two types of springs are investigated defining two distinct systems: a pseudoelastic and a shape memory system. The characterisation of the springs is evaluated by considering differential calorimetry scanning tests and also force-displacement tests at different temperatures. Free and forced vibration experiments are made in order to investigate the dynamical behaviour of the systems. For both systems, it is observed the capability of changing the equilibrium position due to phase transformations leading to hysteretic behaviour, or due to temperature changes which also induce phase transformations and therefore, change in stiffness. Both situations are investigated by promoting temperature changes and also pre-tension of the springs. This article shows several experimental tests that allow one to obtain a general comprehension of the dynamical behaviour of SMA systems. Results show the general thermo-mechanical behaviour of SMA dynamical systems and the obtained conclusions can be applied in distinct situations as in rotor-bearing systems.

• Journal of the Korean Society of Costume
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• v.59 no.2
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• pp.29-41
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• 2009

Perception between real object and recognized subject of human on objective subject is not the same. The reason Is that individual perception of visual design components are transmitted as the image of whole. It is required process of visual perception. Therefore, I developed the vision of seeing image of pattern which is based on Gestalt visual perception theory in clothes. The summary of this study's results is like followings. Extremely antagonistic terms which are specialized by formative characteristics of formative components are clearness and blur of outline/ fixed shape and non-fixed shape/ visuality and tangibility of representation/ simplicity and complexity of structure/ invariability and variability of mobility/ symmetry and asymmetry of arrangements singularity and plurality of group number. The expression of motive shows that clearness, fixed shape, visuality and simplicity pursuit Determination image, and blur, non-fixed shape, tangibility and complexity pursuit Ambiguity image. The arrangements of motive shows that invariability, symmetry and singularity pursuit Order image, and variability asymmetry and plurality pursuit Disorder image. Therefore, the standard of the coordinator of Pattern image positioning is established as Determination and Ambiguity of motive are X-axis, and Order and Disorder of pattern are Y-axis. As the frame of Pattern image positioning, four separated dimensions have made.

• Journal of Mechanical Science and Technology
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• v.14 no.2
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• pp.197-206
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• 2000

A boundary integral equation method in the shape design sensitivity analysis is developed for the elasticity problems with axisymmetric non-homogeneous bodies. Functionals involving displacements and tractions at the zonal interface are considered. Sensitivity formula in terms of the interface shape variation is then derived by taking derivative of the boundary integral identity. Adjoint problem is defined such that displacement and traction discontinuity is imposed at the interface. Analytic example for a compound cylinder is taken to show the validity of the derived sensitivity formula. In the numerical implementation, solutions at the interface for the primal and adjoint system are used for the sensitivity. While the BEM is a natural tool for the solution, more generalization should be made since it should handle the jump conditions at the interface. Accuracy of the sensitivity is evaluated numerically by the same compound cylinder problem. The endosseous implant-bone interface problem is considered next as a practical application, in which the stress value is of great importance for successful osseointegration at the interface. As a preliminary step, a simple model with tapered cylinder is considered in this paper. Numerical accuracy is shown to be excellent which promises that the method can be used as an efficient and reliable tool in the optimization procedure for the implant design. Though only the axisymmetric problem is considered here, the method can be applied to general elasticity problems having interface.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.45-54
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• 2012

Optimization of the asymmetric trapezoidal fin with various upper lateral surface slope is made using a two-dimensional analytic method. For the fixed fin base height, the optimum heat loss, fin length and effectiveness are represented as inner fluid convection characteristic number, fin base thickness, fin base height, fin shape factor and ambient convection characteristic number. For this optimum procedure, the optimum heat loss is defined as 95% of the maximum heat loss from the fin. One of the results shows that optimum heat loss and effectiveness seems independent of the fin shape factor while optimum fin length decreases almost linearly as the fin shape factor increases.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.1-8
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• 2018

BACKGROUND: Different physical and chemical properties of biochar, which is made out of a variety of biomass materials, can impact water movement through amended soil. The objective of this research was to develop a decision support tool evaluating the impact of the shape and the size distribution of biochar on soil saturated hydraulic conductivity ($K_{sat}$). METHODS AND RESULTS: Plastic beads of different size and morphology were compared with biochar to assess impacts on soil $K_{sat}$. Bead and biochar were added at the rate of 5% (v/w) to coarse sand. The particle size of bead and biochar had an effect on the $K_{sat}$, with larger and smaller particle sizes than the original sand grain (0.5 mm) decreasing the $K_{sat}$ value. The equivalent size bead or biochar to the sand grains had no impact on $K_{sat}$. The amendment shape also influenced soil hydraulic properties, but only when the particle size was between 3-6 mm. Intra-particle porosity had no significant influence on the $K_{sat}$ due to its small pore size and increased tortuosity compared to the inter-particle spaces (macro-porosity). CONCLUSION: The results supported the conclusion that both particle size and shape of the amended biochar impacted the $K_{sat}$ value.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.47-52
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• 2010

The proper surface pressure on the pistons rings in the diesel engine of a ship is very important, because the pressure controls the oil that is needed to maintain friction at acceptable levels between the pistons and the cylinders. In this paper, basic and theoretical concepts to compute the ring pressure were formulated and applied to obtain the proper surface pressures on selected sample piston rings. During the calculation of the pressure on the piston rings, the computation of the accurate free shape of the piston ring was required. Earlier, Arnold and Prescott introduced theories to compute the free shapes of piston rings, and their approach used rectangular and polar coordinates. In this paper, the free shapes of piston rings using two different theories were computed and compared. The results were quite close, representing the free shape of the piston ring. Ring pressure was computed using the Arnold's free shape that was obtained. A simple GUI was made to compute the surface pressure on the piston rings.

• The Research Journal of the Costume Culture
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• v.12 no.5
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• pp.743-756
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• 2004

The purpose of this study is to set measurement parts which are important to identify the size and shape of the head in order to produce tightly fitted hats, and to identify detailed sizes and the major factors of head shape classifications of Korean women. A total of 285 Korean women's in the age group of 18 to 35 years old. It were measured through the direct measurement method by selecting 67 measurement items. Materials were analyzed by SPSS Ver.10 and technology statistics and factor analysis were performed according to the agenda. An attempt was made to conduct factor analysis of the measured region of the head in women's. Here, this study drew the head and the facial parts horizontal size as Factor 1, the head and facial parts vertical size as Factor 2, the circumference and width item as Factor 3, the factor representing the form of head height as Factor 4, the factor expressing the proportion of the facial form as Factor 5 and the factor about the frontal and back head form on the plan of the middle as Factor 6. Through this study, we will be able to systemize head measurement materials that can differentiate Korean's head from other peoples' and can use the results in developing head shape models according to Korean's head shape by selecting major head parts needed to identify the sizes and shapes.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.99-108
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• 2006

Aerospace applications use pyrotechnic devices with many different functions. Functional shock, safety, overall system cost issue, and availability of new technologies, however, question the continued use of these mechanisms on aerospace applications. Release device is an important example of a task usually executed by pyrotechnic mechanisms. Many aerospace applications like satellite solar panels deployment or weather balloon separation need a release device. Several incidents, where pyrotechnic mechanisms could be responsible for spacecraft failure, have been encouraging new designs for these devices. The Frangibolt is a non explosive device which comprises a commercially available bolt and a small collar made of shape memory alloy (SMA) that replace conventional explosive bolt systems. This paper presents the modeling and simulation of Frangiblot by the change of bolt size and notch geometry. This analysis may contribute to improve the Frangibolt design.

• The Research Journal of the Costume Culture
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• v.23 no.3
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• pp.439-453
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• 2015

This research is regarding Park Ki-Jong's Western-style court costume and emphasizes the shape and style peculiarities of Western-style court costumes in the Korean Empire from the 1876 Port Opening to the 1910 annexation of Korean to Japan. Park Ki-Jong's frock coat was made during the period of the established law from 1900 to 1910. 1) The brand was ASADA TAILOR from Kyung-Sung. 2) The shape was long at the front and back, and it featured a picked lapel and double breast with six buttons to fasten and two buttons for decoration on the upper part. 3) The frock coat's materials were black wool fabric and black ridged silk. The lining's material was black plain silk and the sleeve's lining was white with blue striped silk. 4) The front separated the upper and bottom parts. The bottom was composed of a one-piece A-line skirt that continued from the front to back. The top of the back was separated by the princess line and the center-back seam was also separated with a vent. However, the center-back of the waistline was not separated, and it continued to one piece. The sleeve shape was a two-piece sleeve style with a phony vent and two wrapping buttons.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.617-623
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• 1990

Cracks present in pressure vessels have been reported to be mostly semi-elliptic surface cracks. The fatigue crack growth rates(FCGR) of surface cracks in the pressure vessel materials, API5A-K55 and SPV 500, used in this study were showed to be different depending on the direction of propagation of the surface crack. An equation for the prediction of the shape change of the surface crack was obtained by combining the Paris' relations for each direction of surface crack extension and agreed well with the experimental data. And also FGGR in both materials were evaluated and prediction of the shape change of surface crack were made using averaged stress intensity factor.