• Ocean Systems Engineering
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• 제4권1호
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• pp.21-37
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• 2014

This paper provides a practical stochastic method by which the burial and scour depths of truncated cones exposed to long-crested (2D) and short-crested (3D) nonlinear random waves can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall (2000) wave crest height distribution representing both 2D and 3D nonlinear random waves. Moreover, the formulas for the burial and the scour depths for regular waves presented by Catano-Lopera et al. (2011) for truncated cones are used. An example of calculation is also presented.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.235.1-235.1
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• 2015

Artificially-engineered materials, whose electromagnetic properties are not available in nature, such as negative reflective index, are called metamaterials (MMs). Although many scientists have investigated MMs for negative-reflective-index properties at the beginning, their interests have been extended to many other fields comprising perfect lenses. Among various kinds of MMs, metamaterial absorbers (MM-As) mimic the blackbody through minimizing transmission and reflection. In order to maximize absorption, the real and the imaginary parts of the permittivity and permeability of MM-As should be adjusted to possess the same impedance as that of free space. We propose a dual-wide-band and polarization-independent MM-A. It is basically a triple-layer structure made of metal/dielectric multilayered truncated cones. The multilayered truncated cones are periodically arranged and play a role of meta-atoms. We realize not only a wide-band absorption, which utilizes the fundamental magnetic resonances, but also another wide-band absorption in the high-frequency range based on the third-harmonic resonances, in both simulation and experiment. In simulation, the absorption bands with absorption higher than 90% are 3.93 - 6.05 GHz and 11.64 - 14.55 GHz, while the experimental absorption bands are in 3.88 - 6.08 GHz and 9.95 - 13.84 GHz. The physical origins of these absorption bands are elucidated. Additionally, it is also polarization-independent because of its circularly symmetric structures. Our design is scalable to smaller size for the infrared and the visible ranges.

• Advances in Computational Design
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• 제1권4호
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• pp.345-356
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• 2016

Notwithstanding a considerable body of references in the literature on the buckling response of conical shell structures, it seems imperative to provide further insight on the buckling response of locally imperfect steel cones. This paper contains different simulations including non-linear FE analysis and discusses the influence of dent imperfection on the buckling load of these structures subject to external pressure. Data of the present work are evaluated against available experimental results, codes and recommendations and the effect of the local damages is exhaustively set forth. It is also found that the employed FE program can reliably predict the structural response of locally damaged conical shells.

• 한국의류학회지
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• 제21권5호
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• pp.807-820
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• 1997

This exploratory research was intended to develop and test a slacks pattern based upon conic model. Data came from measurements of photograph of three subjects. Silhouette of slacks was close fit on waist and hip and loose under hip level. This three-dimensional form was modeled with truncated cones. This conic model was truncated by plane of the waist level, the abdomen level, the hip level, the crotch level and the ankle level parallel to the floor. Two models that have differences in back part of the model were tested. Drafted patterns from two models were taken for each subject. Drafted experimental pattern was operated for slacks pattern. The first step was to make sideseam. Parts over crotch level were moved to both sides. And then to make waistdarts. Experimental pattern had two darts each in front and back. Each experimental slacks was evaluated by sensory test to appearance and comfort by five judges. The results can be summarized as follows. 1) Appearance and comfort of experimental pattern were judged to be satisfactory. Especially these patterns were fitted we18 in waist darts front and back. So we evaluated that was proper pattern for slacks. 2) Model 2 was better in appearance than model 1. But Model 1 was more comfortable in non significant difference. This was supposed to be resulted from fit more closely of model 2. 3) considering preceding results, this geometric model based upon truncated cone was applicable for slacks pattern.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권4호
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• pp.268-272
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• 2002

This paper presents a novel microfabrication technology of 3D microstructures with inclined/rotated UV lithography using negative photoresist, SU-8. In some cases, reflected UV as well as incident UV is used to form microstructures. Various 3D microstructures are simply fabricated such as embedded channels, bridges, V-grooves, truncated cones, and so on.

• Structural Engineering and Mechanics
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• 제54권4호
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• pp.649-664
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• 2015

In this study, the authors present an analytical approach to find the axisymmetric buckling load of two joined isotropic conical shells under axial compression. The problem of two joined conical shells may be considered as the generalized form of joined cylindrical and conical shells with constant or stepped thicknesses. Thickness of each cone is constant; however it may be different from the thickness of the other cone. The boundary conditions are assumed to be simply supported with rigid rings. The governing equations for the conical shells are obtained and solved with an analytical approach. A simple closed-form expression is obtained for the buckling load of two joined truncated conical shells. Results are compared and validated with the numerical results of finite element method. The variation of buckling load with changes in the thickness and semi-vertex angles of the two cones is studied. Finally, application of the results in practical design and range of engineering validity are investigated.

• 한국수학교육학회지시리즈A:수학교육
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• 제63권3호
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• pp.451-466
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• 2024

본 연구는 학교 수학에서 다소 모호한 개념을 보이는 모선에 대한 초등 예비교사들의 인식을 조사하였다. 예비교사의 모선에 대한 인식은 '원뿔에만 모선이 있다는 인식', '원뿔과 원기둥에만 모선이 있다는 인식', '회전체에 모선이 있다는 인식', '옆면에 있는 직선이 모선이라는 인식'의 4가지 유형으로 크게 구분되었다. 원뿔에만 모선이 있다는 인식은 전체 예비교사의 22.1%로, 이 유형의 예비교사들은 초등학교 교과서에 제시된 모선의 정의를 대부분 따르고 있었다. 원뿔과 원기둥에만 모선이 있다는 인식은 가장 낮은 비율로 조사된 유형이었지만, 도선을 이용한 방법으로 모선을 정의한 사례가 있었다는 점에서 원뿔대의 모선과 같은 심화된 내용을 고안할 필요가 있었다. 회전체에 모선이 있다는 인식은 전체 예비교사의 27.9%로, 이 유형의 예비교사들은 구에 모선이 있는지에 대한 의견이 나뉜다는 특징이 있었다. 옆면에 있는 직선이 모선이라는 인식은 가장 높은 비율로 조사된 유형으로, 도선을 이용한 방법을 함의하여 모선을 정의한다는 점에서 학교 수학의 관점과는 차별화된 인식을 보였다. 이와 같은 연구 결과를 바탕으로 예비교사의 교과 내용 지식과 교수학적 내용 지식을 고려한 구체적인 교사교육 방안을 마련하였다. 나아가 수학교육 관점에서 합의된 모선의 정의를 제안하였다.