• Smart Structures and Systems
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• 제13권1호
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• pp.111-135
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• 2014

Based on the Reissner mixed variational theorem (RMVT), finite rectangular layer methods (FRLMs) are developed for the three-dimensional (3D) linear buckling analysis of simply-supported, fiber-reinforced composite material (FRCM) and functionally graded material (FGM) sandwich plates subjected to bi-axial compressive loads. In this work, the material properties of the FGM layers are assumed to obey the power-law distributions of the volume fractions of the constituents through the thickness, and the plate is divided into a number of finite rectangular layers, in which the trigonometric functions and Lagrange polynomials are used to interpolate the in- and out-of-plane variations of the field variables of each individual layer, respectively, and an h-refinement process is adopted to yield the convergent solutions. The accuracy and convergence of the RMVT-based FRLMs with various orders used for expansions of each field variables through the thickness are assessed by comparing their solutions with the exact 3D and accurate two-dimensional ones available in the literature.

• Journal of information and communication convergence engineering
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• 제1권4호
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• pp.169-173
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• 2003

The performance of modern mainframe computers keeps increasing due to the advances in the semiconductor technology. However, the quest for the faster computer has never been satisfied. To overcome the discrepancy in the supply and demand, we studied a high performance computer architecture utilizing a three-dimensional Holographic Data Storage Systems (HDSS) as a secondary storage system. The HDSS can achieve a high storage density by utilizing the third dimension. Furthermore, the HDSS can exploit the parallelism by processing the two-dimensional data in a single step. To compare the performance of the HDSS with the conventional hard disk based storage system, we modeled the HDSS using the DiskSim simulation engine and performed the simulation study. Results showed that the HDSS can improve the access time by 1.7 times.

• Nuclear Engineering and Technology
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• 제45권1호
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• pp.89-98
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• 2013

In recent years steel-concrete composite shear walls have been widely used in enormous high-rise buildings. Due to high strength and ductility, enhanced stiffness, stable cycle characteristics and large energy absorption, such walls can be adopted in the auxiliary building; surrounding the reactor containment structure of nuclear power plants to resist lateral forces induced by heavy winds and severe earthquakes. This paper demonstrates a set of nonlinear numerical studies on I-shaped composite steel-concrete shear walls of the nuclear power plants subjected to reverse cyclic loading. A three-dimensional finite element model is developed using ABAQUS by emphasizing on constitutive material modeling and element type to represent the real physical behavior of complex shear wall structures. The analysis escalates with parametric variation in steel thickness sandwiching the stipulated amount of concrete panels. Modeling details of structural components, contact conditions between steel and concrete, associated boundary conditions and constitutive relationships for the cyclic loading are explained. Later, the load versus displacement curves, peak load and ultimate strength values, hysteretic characteristics and deflection profiles are verified with experimental data. The convergence of the numerical outcomes has been discussed to conclude the remarks.

• 한국융합학회논문지
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• 제8권11호
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• pp.413-421
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• 2017

본 연구는 심각해지는 대기 중 미세먼지 현실에 따라 우리나라 사람들의 미세먼지 관련 건강 인식과 행동에 대해 탐색하였다. 개인 위생적 차원에서 미세먼지에 대한 우리나라 사람들의 인식과 건강행동 사이의 관계를 탐색하기 위해 개인의 건강 인식과 관련 있는 다차원 건강통제소재, 질병에 대한 취약성과 심각성 지각 및 건강행동의도 사이의 구조적 관계를 분석하였다. 다차원 건강통제소재의 3가지 성향 중 내적 성향을 제외한 우연성향과 타인의존성향이 취약성과 심각성 지각에 영향을 미치고 있었고, 두 변인은 다시 미세먼지로 인한 질병 예방행동의도에 긍정적인 영향을 미치고 있었다. 이러한 결과에 따라 미세먼지 관련 질병 예방행동을 장려하기 위해 정확한 정보를 시의성 있게 제공하고 피해 최소화를 위한 방안을 제안하여 미세먼지에 대한 막연한 공포감이나 불확실성을 제거하고 이를 통해 내적 통제소재화를 자극할 수 있도록 독려할 필요가 있다. 끝으로 후속연구를 위한 제언을 제안했다.

• 소음진동
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• 제8권2호
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• pp.267-273
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• 1998

This study aims at performing sensitivity analysis of piezoelectric smart structure for minimizing radiated noise from the structure, The structure consists of a flat plate on which disk shaped piezoelectric actuator is mounted, and finite element modeling is used for the structure. The finite element modeling uses a combination of three dimensional piezoelectric, flat shell and transition elements so thus it can take into account the coupling effects of the piezoelectric device precisely and it can also reduce the degrees of freedom of the finite element model. Electric potential on the piezoelectric actuator is taken as a design variable and total radiated power of the structure is chosen as an objective function. The objective function can be represented as Rayleigh's integral equation and is a function of normal displacements of the structure. For the convenience of computation, all degrees of freedom of the finite element equation is condensed out except the normal displacements of the structure. To perform the design sensitivity analysis, the derivative of the objective function with respect to the normal displacements is found, and the derivative of the norma displacements with respect to the design variable is calculated from the finite element equation by using so called the adjoint variable method. The analysis results are compared with those of the finite difference method, and shows a good agreement. This sensitivity analysis is faster and more accurate than the finite difference method. Once the sensitivity analysis program is used for gradient-based optimizations, one could achieve a better convergence rate than non-derivative methods for optimal design of piezoelectric smart structures.

• 한국융합학회논문지
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• 제9권10호
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• pp.237-242
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• 2018

마이크로 믹서는 랩-온-어-칩이나 마이크로 유체 기기의 하나의 구성품으로 두 가지의 화학 물질을 혼합(융합)하는 장치이다. 본 연구는 다양한 형상의 패시브 마이크로 믹서의 성능을 평가하는 것을 목적으로 한다. 다양한 형상의 마이크로 믹서는 총 6가지의 형상을 비교하였고, 서로 동일한 수력 직경을 갖도록 3차원 모델링하였다. 내부 혼합 유동을 전산모사하기 위해여 상용 유동해석 프로그램인 ANSYS Fluent를 사용하였다. 수치해석 방법은 본 논문에 자세하게 기술하였다. 마이크로 믹서의 성능 평가는 혼합 지수와 압력 강하로 비교하였고, 결론적으로 CDM-8T은 합리적인 혼합성능과 상대적으로 낮은 압력 강하를 갖는 것으로 나타났다.

• 한국기계가공학회지
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• 제17권6호
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• pp.170-176
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• 2018

Recently, weapon system requires personal protection products due to the explosion of rapid-fire explosion, which is considered to be multi threat in modernization, complication and war against terrorism. However, the conventional Korean military bullet protection helmets are not suitable for wearing convenience and combatant interoperability in terms of ergonomic. In this paper, we propose a suitable 3D Scanning method for the head, and compare the measured 3D dimension with the existing 2D measurement value to identity the reliability. Reverse engineered soldier head using the quick surface method was realized with a perfect free-form surface and satisfactory tolerance range (${\pm}0.2mm$). Through the comparison of 3D and 2D measured head dimensions, the absolute error value was 0.73 mm on average and relative error was 0.35 %, confirming the high accuracy of the 3D scan modeling. Also, quick surface method using 3D scanner is suggested a fast and accurate skill for ergonomics in obtaining the head modeling needed for military's personal bullet protection helmet design.

• 한국전자통신학회논문지
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• 제16권5호
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• pp.879-888
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• 2021

정보통신기술의 발달로 실감미디어를 활용한 간접 체험 콘텐츠의 수요가 증가하고 있다. 실감미디어는 만들 때 모델들의 전체적인 느낌이 일정하게 유지되어야 콘텐츠를 즐길 때 몰입감을 유지하게 해 준다. 관광지에 대한 간접 체험을 제공하는 실감미디어의 경우 관광지의 실제 정보를 반영한 모델링이 되어야 정확한 체험을 제공할 수 있다. 본 논문에서는 남해안의 대표적인 관광자원인 섬을 실제 데이터를 반영하여 3차원으로 모델링하는 방법을 제안한다. 제안하는 방법에서는 구조화된 절차에 따라 모델링을 하기 때문에 여러 사람이 공동으로 작업하여 콘텐츠를 제작하여도 쉽게 전체 모델의 일관성을 유지하게 해 준다. 우도 섬의 정보를 이용한 모델링 결과를 보면 제안하는 방법이 단순히 높이 정보를 이용한 모델링 방법 보다 사실적인 결과를 만드는 것을 보여준다.

• Structural Engineering and Mechanics
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• 제66권4호
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• pp.487-494
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• 2018

The purpose of the present paper is to study the bending and free vibration of Functionally Graded Material (FGM) plate using user-defined material subroutine on the finite element software ABAQUS. The FGM plate is simply supported and subjected to sinusoidal and uniform load. The Poisson's ratio is kept constant. The results obtained compared to those available in the literature show the convergence, the exactitude and the efficiency of the method used with various power index of the materials.

• International journal of advanced smart convergence
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• 제6권1호
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• pp.9-17
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• 2017

Recent development in virtual and augmented reality increases the demand for content in many different fields. One of the fast ways to create content for VR is 3D modeling of real objects. In this paper we propose a system to reconstruct three-dimensional models of real objects from the set of two-dimensional images under the assumption that the subject does not has distinct features. We explicitly consider an object that is made of one or more surfaces and radiant constant energy isotropically. We design a low cost portable multi camera rig system that is capable of capturing images simultaneously from all cameras. In order to evaluate the performance of the proposed system, comparison is made between 3D model and a CAD model. A simple algorithm is also proposed to acquire original texture or color of the subject. Using best pattern found after the experiments, 3D model of the Pyeongchang Olympic Mascot "Soohorang" is created to use as VR content.