• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.192-197
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• 2017

Typical materials including concrete behaves with positive poisson's ratio when external force is applied. However, it is also available to manufacture a grating system which has negative poisson's ratio(Auxetic). In this study, double arrow type 2-D auxetic mesh was manufactured and mechanical behaviors were observed. Also, direct tensile tests of cementitious composites reinforced by auxetic mesh were performed and the results were compared with composites reinforced by typical mesh. The results showed that auxetic mesh more effectively restrained the deformation(shortening) of cementitious composites perpendicular to the load direction comparing with typical mesh.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.297-299
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• 2007

본 논문은 유한한 유전체 격자구조에 입사되는 TE필드가 유전체 내부에 발생시키는 모드의 필드 분포와 방출하는 필드를 분석하였다. 입사되는 필드는 유전체 격자구조에 일정한 패턴의 모드를 형성한다. 유한한 길이의 격자구조의 영향을 받아 유전체 내부에 유한개의 모드가 만들어지며 모드들은 각기 독립적인 방사패턴을 갖는다. 이러한 방사패턴을 분석함으로써 실제로 제작되는 유전체 격자구조의 분석에 도움이 될 것으로 사료된다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.198-203
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• 2017

This study observed the effects of auxetic mesh reinforcement in concrete on the mechanical characteristics under compression. Series of double arrow type 2-D auxetic mesh were manufactured and embedded into concrete specimens. Compression tests were performed and results showed that the application of auxetic mesh as concrete reinforcement can restrain the deformation of concrete resulting in the enhancement of stiffness of composites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.116-123
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• 2017

This study has been investigated the applicability of auxetic mesh for the reinforcement of structural members. Typical materials including concrete behaves with positive poisson's ratio when external force is applied. In this study, it has been theoretically verified that metallic auxetic mesh restrains as such mechanical behaviors of concrete resulting in the stiffness increase. Also, regarding the applicability to construction field, a type of auxetic mesh has been suggested and the mechanical characteristics were numerically analyzed.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.74-86
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• 2021

The composite lattice structure is a structure that supports the required load with the minimum weight and thickness. Composite lattice structure is manufactured by the filament winding process using impregnating high-strength carbon fiber with an epoxy resin. Filament winding process can laminate and manufacture only structurally necessary parts, composite lattice structure can be applied to aircraft fuselages, satellite and launch vehicles, and guided weapons to maximize weight reduction. In this paper, the development and evaluation of the composite lattice structure corresponding to the entire process from design, analysis, fabrication, and evaluation of large-scale cylindrical and conical composites lattice structure were performed. To be applicable to actual projectiles and guided weapons, we developed a cylindrical lattice structure with a diameter of 2,600 mm and a length of 2,000 mm, and a conical lattice structure with an upper diameter of 1,300 mm, a lower diameter of 2,500 mm, and a length of 900 mm. The performance of the developed composite lattice structure was evaluated through a load test.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.703-708
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• 1995

지진 및 냉각재상실사고와 같은 외력에 대한 집합체 구조적 건전성 분석을 위한 해석시 필요한 지지격자의 동적 특성치들을 얻기 위해 17$\times$17 JDFA 중간지지격자에 대한 충격시험을 수행하였으며, 지지격자에 대한 허용충격하중값(Crush Strength)을 구하고 Impact Duration Method를 이용하여 집합체 구조해석에 필요한 지지격자의 동적 강성도 (Dynamic Stiffness)를 구하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1175-1183
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• 2010

A spacer grid assembly is one of the most important structural components in a Light Water Reactor(LWR) nuclear fuel assembly. In the case of the Zircaloy spacer grid assembly, the primary design consideration is to ensure that lateral dynamic crush strength of the spacer grid assembly is sufficient to resist design basis loads and thereby prevent seismic accidents, without a significant increase in the hydraulic head loss for the reactor coolant in the reactor core. In this study, factors affecting the lateral dynamic crush strength of a spacer grid assembly were analyzed by performing lateral dynamic crush tests and finite element analyses. Further, an effective and economical method to enhance the lateral dynamic crush strength of the spacer grid assembly is proposed.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.130-140
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• 1997

원형주상체 주위의 유동을 규명하기 위해 회류수조에서 원주방향으로 24개의 위치에 대하여 압력을 계측하였으며, laser sheet을 이용하여 유동을 가시화 하였다. Reynolds수가 4800에서 40000인 범위에 대하여 실험을 수행하였다. 또한, 원형단면체 주위의 비정상 층류유동에 대한 Navier-Stokes방정식의 해를 구하는 수치해석기법을 개발하였다. 효과적인 격자배치를 위하여 H와 O-type의 중첩격자를 사용하였고, 이산화 방법으로는 정규격자시스템에서 유한차분법을 적용하였다. 실험과 수치해석결과에서 뚜렷한 와류박리현상을 볼 수 있었으며, 압력계수 (C$_{p}$ ), 항력계수(C$_{D}$), 스트로얼수(St)를 정량적으로 비교하였을 때, 비교적 잘 일치하는 것을 확인하였다.다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.835-837
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• 2017

In this paper, manufacturing processes of cylindrical composite lattice structures using filament winding method was described. Cylindrical composite lattice structures were manufactured in accordance with four major steps. Silicon mold of lattice shape was installed on mandrel and then continuous fiber was wound on silicon mold. After winding process, in order to ensure the same thickness for all regions, compression process was done for its intersection parts. Finally, the composite lattice structure was demoulded after curing in oven. It was found that the manufactured cylindrical composites lattice structure had 2.4% of dimensional error compared to the design requirements.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.123-125
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• 2007

본 논문에서는 유한한 유전체 격자구조에 수직으로 입사되는 전자기파가 갖는 유효 굴절율을 구하고자 한다. 유전체 격자구조를 다층구조로 모델링하여 모드에 따른 전파상수를 계산하면 주어진 주파수에 따른 유효 굴절율을 계산할 수 있다. 다층구조에서 유효 굴절율을 계산을 응용하면 유전체 모양이나 구조에 따른 유효굴절율을 계산할 수 있으며 주파수 선택특성이나 도파관등에 진행모드 계산에 도움이 될 것으로 사료된다.