• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.153-157
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• 1992

본 연구에서는 복합재료와 혼합적층 외팔형 삼각판의 동적거동을 실험을 통하여 파악하였다. 또한 실험 결과들의 비교를 위해서 FEM 해석을 수행하였다. 실험과 FEM의 결과들은 고유진동수(Hz)로 제시하였고, 또한 참고문헌과의 비교를 위해서 무차원 진동수매개 변수로 나타내었다. 그리고 외팔형 삼각판의 노달라인을 나타내었다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.9
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• pp.341-348
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• 1985

This paper deals with a surface charge simulation method of calculating three-dimensional electric fields and capacitance. The principle is to divide the electrode surface into rectangular or triangular elements of which charge density is the linear function of the electrode coordinate and to formulate a linear equation for the coefficients of charge density function and to determine those coefficients by boundary conditions. It has been shown that the method can give satisfactory results for thin rectangular plates where the other methods is difficult to be applied.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.141-152
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• 2018

The heating process such as line heating, triangular heating and so on is widely used in plate forming of shell plates found in bow and stern area of outer shell in a ship. Local shrinkage during heating process is main physical phenomenon used in plate forming process. As it is well appreciated, the heated plate undergoes the change in material and mechanical properties around heated area due to the harsh thermal process. It is, therefore, important to investigate the changes of physical and mechanical properties due to heating process in order to use them plate the design stage of shell plates. This study is concerned with the development of formula of plastic hardening constitutive equation for steel plate on which line heating is applied. In this study the stress correction formula for the heated plate has been developed based on the numerical simulation of tension test with varying plate thickness and heating speed through the regression analysis of multiple variable case. It has been seen the developed formula shows very good agreement with results of numerical simulation. This paper ends with usefulness of the present formula in examining the structural characteristic of ship's hull.

• Steel and Composite Structures
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• v.46 no.4
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• pp.471-483
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• 2023

This paper presents an analytical hyperbolic theory based on the refined shear deformation theory for mechanical stability analysis of the simply supported advanced composites plates (exponentially, sigmoidal and power-law graded) under triangular, trapezoidal and uniform uniaxial and biaxial loading. The developed model ensures the boundary condition of the zero transverse stresses at the top and bottom surfaces without using the correction factor as first order shear deformation theory. The mathematical formulation of displacement contains only four unknowns in which the transverse deflection is divided to shear and bending components. The current study includes the effect of the geometric imperfection of the material. The modeling of the micro-void presence in the structure is based on the both true and apparent density formulas in which the porosity will be dense in the mid-plane and zero in the upper and lower surfaces (free surface) according to a logarithmic function. The analytical solutions of the uniaxial and biaxial critical buckling load are determined by solving the differential equilibrium equations of the system with the help of the Navier's method. The correctness and the effectiveness of the proposed HyRPT is confirmed by comparing the results with those found in the open literature which shows the high performance of this model to predict the stability characteristics of the FG structures employed in various fields. Several parametric analyses are performed to extract the most influenced parameters on the mechanical stability of this type of advanced composites plates.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.259-262
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• 2009

The influence of pre-strain in low-cycle fatigue behavior of Fe-18Mn-0.05Al-0.6C TWIP steel was studied by conducting axial strain-controlled tests. As-received plates were deformed by rolling with reduction ratios of 10 and 30%, respectively. A triangular waveform with a constant frequency of 1 Hz was employed for low cycle fatigue test at the strain amplitudes in the range of ${\pm}0.4{\sim}{\pm}0.6$ pct. The results showed that low-cycle fatigue life was strongly dependent on the amount of pre-strain as well as the strain amplitude. Increasing the amount of prestrain, the number of reversals to failure was significantly decreased at high strain amplitudes, but the effect was negilgible at low strain amplitudes. A new model for predicting fatigue life of pre-strained body has been devised adding a correction term of ${\Delta}E_{pre-strain}$ to the energy-based fatigue damage parameter.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.3
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• pp.60-66
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• 1991

In this paper, circula and rectangular apertures arranged with triangular and rectangular lattices and having a certain thickness are considered for eddective electromagnctic wave shielding when the plane wave is incident normally to the perfectly conductingmaterrial. The shielding effectiveness is represented by the transmitted power which can be obtained by reflection and transmission coefficients using Floquet mode representation.

• Animal Systematics, Evolution and Diversity
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• v.29 no.2
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• pp.179-183
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• 2013

The perlid stonefly Brahmana flavomarginata Wu, originally described from China from the male adult, is described using reared male and female adults and nymphs from Vietnam. The male adult of B. flavomarginata is distinguished from its congeners by the blackish-brown body color and distinct head marking, hemitergal triangular chitin plates, and a median semicircular smooth subgenital plate (hammer) on the abdominal sternum IX. The female adult has a large and round subgenital plate which extends to the posterior margin of the abdominal sternum X. The nymph can be distinguished by the relatively small compound eyes and the body covered by many long stout setae and short golden brown hair-like setae. This species is known in southwestern China (Yunnan Province) and northern Vietnam (Lao Cai Province, Cao Bang Province).

• Smart Structures and Systems
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• v.26 no.3
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• pp.311-318
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• 2020

The goal of this study is to analytically and non-stochastically generate structural uncertainty behaviors of isotropic beams and laminated composite plates under plane stress conditions by using an interval finite element method. Uncertainty parameters of structural properties considering resistance and load effect are formulated by interval arithmetic and then linked to the finite element method. Under plane stress state, the isotropic cantilever beam is modeled and the laminated composite plate is cross-ply lay-up [0/90]. Triangular shape with a clamped-free boundary condition is given as geometry. Through uncertainties of both Young's modulus for resistance and applied forces for load effect, the change of structural maximum deflection and maximum von-Mises stress are analyzed. Numerical applications verify the effective generation of structural behavior uncertainties through the non-stochastic approach using interval arithmetic and immediately the feasibility of the present method.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.16-24
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• 2007

The high-frequency analysis method of back-scattering cross section spectrum of rotating targets is established. The time history of the back-scattering cross section is calculated using a quasi-stationary approach, based on a physical optics and a physical theory of diffraction, combining an adaptive triangular beam method to consider the shadow effect. And the spectra of back-scattering cross section by the Doppler effect are analyzed applying a simple fast Fourier transform method to its time history. The numerical calculation for rotating targets, such as rotating metal plates and underwater propeller, are carried out. The time history appears to be periodic with respect to the number of wings. The backscattering cross section spectrum level and its frequency shift are dependent on the rotating speed, direction, and the shape of the targets.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.289-292
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• 2021

Henricia specimen was collected from the East Sea of Korea using fishing nets. The specimen was identified as Henricia hayashii (Djakonov 1961), belonging to the family Echinasteridae of the order Spinulosida. This species can be distinguished from other Henricia species by slender arms (R/r=7.4), constricted arm base, six to thirty-five slender spinelets, open-meshed, reticulated abactinal skeleton comprising semi-triangular, rod-like form, and small ossicles present inside the papular areas. This species superficially resembles H. reniossa in terms of its body size but differs in the shape and arrangement of the abactinal and actinal plates. To date, two genera of Echinasteridae, Aleutihenricia and Henricia, including a total of 14 species, have been reported in Korea. Herein, the morphological characteristics of H. hayashii are described, and photographs are provided.