• Journal of Applied Reliability
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• v.13 no.2
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• pp.141-151
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• 2013

The study of environmental stress cracking (ESC) by contact with plastic rulers and PVC erasers which was artificially added to the external stress was carried out in order to accelerate the chemicals crack. To analyze a blooming plasticizer that migrates from the inside of blended eraser to the surface of the eraser, the ESC experiments were carried out at room temperature and $50^{\circ}C$ conditions. The chemicals crack shape caused by the plasticizer and the brittle fracture shape resulted from the external stress were observed in consequence with the cross-sectional surface analysis of the ruler crack by the ESC. The bending strength of the plastic rulers were fractured prior to the yield point and it had low bending flexure stress. We presented that ESC of polymer materials was affected by the polarity of the chemicals and polymer, the exposure time to chemicals, the exposure temperature and the level of strain on the polymer.

• Smart Structures and Systems
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• v.7 no.1
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• pp.41-57
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• 2011

A deeper understanding of the effectiveness of adopting devices mounting shape memory alloy (SMA) elements in applications targeted to the mitigation of vibrations is pursued via an experimental approach. During a seismic event, less than 1000 loading-unloading cycles of the alloy are required to mitigate the earthquake effects. However, the aging effects during the time of inactivity prior to the oscillations (several decades characterized by the yearly summer-winter temperature wave) should be considered in order to avoid and/or minimize them. In this paper, the results obtained by carrying out, in different laboratories, fatigue tests on SMA specimens are compared and discussed. Furthermore, the effects of seismic events on a steel structure, with and without SMA dampers, are numerically simulated using ANSYS. Under an earthquake excitation, the SMA devices halve the oscillation amplitudes and show re-centering properties. To confirm this result, an experimental campaign is conducted by actually installing the proposed devices on a physical model of the structure and by evaluating their performance under different excitations induced by an actuator.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.1
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• pp.75-83
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• 1995

The purpose of this study is to investigate the effect of heat treatments on the martensite transformation and tensile deformation behavior in Ti-Ni-B alloys with various boron concentration. Three types of heat treatment are given to the specimens; i) solution treatment ii) aging iii) thermo-mechanical treatment. In solution treated specimens. R-phase transition which is related to abnormal increase of electrical resistance prior to martensitic transformation has been formed at a boron content of 0.2at % and the $M_s$ temperature has been decreased with the increasing of boron content. However. It has not been affected by aging, while that of thermo-mechanically treated specimens has been remarkably increased in the vicinity of recrystallization temperature. The thermo-mechanically treated specimen has showed a good thermal fatigue characteristics, shape memory effect and superelasticity in comparison with the solution treated specimen.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.904-907
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• 2014

In this work we present a robust and fast approach to estimate 3D vehicle pose that can provide results under a specific traffic surveillance conditions. Such limitations are expressed by single fixed CCTV camera that is located relatively high above the ground, its pitch axes is parallel to the reference plane and the camera focus assumed to be known. The benefit of our framework that it does not require prior training, camera calibration and does not heavily rely on 3D model shape as most common technics do. Also it deals with a bad shape condition of the objects as we focused on low resolution surveillance scenes. Pose estimation task is presented as PnP problem to solve it we use well known "POSIT" algorithm [1]. In order to use this algorithm at least 4 non coplanar point's correspondence is required. To find such we propose a set of techniques based on model and scene geometry. Our framework can be applied in real time video sequence. Results for estimated vehicle pose are shown in real image scene.

• Journal of Korean Association for Spatial Structures
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• v.21 no.1
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• pp.105-112
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• 2021

In this paper, the dynamic response was analyzed by performing linear dynamic analysis using historic earthquake loads on twisted-shaped structures and fixed structure among free-form high-rise structures with atypical elevation shape following prior studies. In addition, the dynamic characteristics of the analysis models according to the plane rotation angle of the twisted structure were compared and analyzed. As a result of the analysis, as the plane rotation angle of the twisted structure increased, the interlayer deformation rate increased in the high-rise part of 50th floors or more. The story shear force and the story absolute acceleration were similar in the entire structure. In the case of the story shear force, the response of the twisted shape model was rather reduced in the middle part. As a result of analyzing the dynamic response, the vulnerable layer where the response amplification of the twisted structure occurs was found to be 31st story.

• Journal of Elementary Mathematics Education in Korea
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• v.24 no.1
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• pp.151-168
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• 2020

The use of software is effective in developing mathematical understanding that provides mathematical problems and ensures mathematical communication. In particular, various software may provide all of the skills and conceptual activities students need to understand mathematical concepts. Based on these arguments, I analyze domestic prior studies based on the perspective of how the shape education using software affects mathematics learning. Based on the five categories of visualization, manipulation, cognitive tools, discourse promoters, and ways of thinking, domestic studies have shown that the number and categories of research related to shape education using software are limited. In addition, it was confirmed that previous studies in South Korea have been focused on the application of software rather than analysis of the changing aspects of learners' mathematics learning. These implications might be used as a basis for setting the direction of research on mathematics education related to the education of software utilization in the future.

• Journal of the Ergonomics Society of Korea
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• v.36 no.4
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• pp.305-323
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• 2017

Objective: The purpose of this study was to determine breast shape and ratio of breast enlargement women prior to development of breast enlargement patient's bra. Background: Although there are many previous studies on women's breast that did not undergo breast augmentation surgery, no studies have examined the breast type and proportion of women with breast augmentation. Method: In this study, we analyzed ratios and angles with photographs taken before and after breast augmentation on the frontal and lateral views of the breast, UPF and projection were analyzed too. We also compared the pre-operative and post-operative rates with those of previous breast studies, as well as the post-operative breast types for the desirable breast types. Results: The length and width of the breast base and the height of the breast projection increased after the operation. The rate of increase in width is larger than the vertical distance in the breast base, and the rate of increase in height of the projection is larger than the increase in the width. Specifically, in the vertical distance, the rate of increase in the lower portion is larger than that in the upper portion. In the width, the rate of increase on the inside is larger than that on the outside. Conclusion: The angles of the static relationship with the projection increased and the angles of the minor relation decreased. The changes in the size of the breast were visually observed in the overlapping of the triangle shape before and after the surgery. The changes were composed of the line connecting the angle and the measurement points. The pre-operative upper pole fullness (UPF) was mostly 0 and - 1, but after the surgery, +1, 0, -1, +2 were distributed, while post-operative levels of projection were distributed in the order of level 3> level 1> level 2. In comparison with the desirable breast type, it was found that the anatomical type was a more natural breast type than the round type of implant. Application: These results can be useful as basic data for the breast analysis of breast enlargement patients and their bra patterns.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1201-1206
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• 2008

This study is focused on the investigation of the modal characteristics of the preliminary models of science technology satellite-3 (STSAT-3). Prior to the final decision of the composite structure model, several candidate structure models have been developed so as to find the most qualified structures with respect to the satellite structure systems' requirements and then utilize the information achieved to a real design. The main structure is composed of fiber reinforced composite faced honeycomb sandwich panel whose modal characteristics are found and compared to each other by means of finite element numerical analyses. Results from the current study demonstrate that a rectangular box shape having supporting inner panel shows relatively higher fundamental mode frequencies than octagonal box shape and etc., and regardless of the structure model shape tested herein, the fundamental mode turns out lateral bending mode.

• The Research Journal of the Costume Culture
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• v.28 no.3
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• pp.356-375
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• 2020

The purpose of this study is to understand the characteristics and cultural values of the headdress among Chinese minorities with diverse ethnic cultures, and to provide various data on the design of clothing accessories. Theoretical considerations about ethnic minorities were addressed through literature and prior research, with data being collected using literature and websites. The results are as follows. First, the most common type of headdress is the horizontal type, which includes the head style, headband, and head scarf. The second most common is the cylinder type, which is a headdress with variations in the shape of a round hat, and has is evident among various minorities. Third, the pagoda type is decorated with ornaments mounted on top of a round shape. Fourth, the square crown type is a piece of wood as a material for a form of the material and for a variety of jewelry and the production of up to meet the women's head of the jewelry. Fifth, head belt-type ornaments consist of a headband and fancy bead ornaments from the bottom of the head. Mongol women usually wear an exaggerated form of this type. Sixth, the head cover type is a head decoration influenced by the dress code of Muslim women. Seventh is the disc type of crown shape worn by the Dai. Next, the ogival type is a cone-shaped headdress hat most commonly seen as head ornament hat among the Dai. Lastly, the sailboat type is the most exaggerated form of hair ornaments found among ethnic minorities.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.71-74
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• 2005

In manufacturing automotive parts, such as engine cradles, frame rails, subframes, cross-members, and other parts from circular tubes, pre-bending and pre-forming operations are often required prior to the subsequent tubular hydroforming process. During some pre-forming operations, the cross section of a bent circular tube is crushed into an oval-like shape to ensure proper geometry and sufficient clearance in the hydroforming dies. For such applications, the use of oval Instead of circular tubes could be an effective means of eliminating the pre-forming step. The oval tube could also be produced with less thinning and with less strain on the outside of the bend when controlled by a booster system without the use of mandrel. Hence, the understanding of the issues that occur in the bending of oval tubes is worthy of Investigation. This paper presents parametric studies on the bending of oval tubes without a mandrel. The finite element modeling technique is used to examine the deformation characteristics for both circular and oval tubes. In the simulations, the bending process parameters of bend radius, aspect ratio of the tube ovalness, and tube wall thickness are varied. Observations are made to obtain a hoop-buckle limit diagram in terms of a non-dimensional shape degradation factor. Suggestions based upon developed criteria are made on the acceptability of bend tubes suitable for hydroforming applications without the need ofa pre-forming step or the used of a mandrel.