• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.261-264
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• 2011

유한 요소 기법을 이용한 허니콤 구조물의 해석은 모델링 작업 및 격자 생성의 어려움뿐만 아니라 과도한 해석 시간이 요구되기 때문에 균질화 기법은 계산상의 효율성을 증대시킬 수 있는 매우 유용한 방법이라 할 수 있다. 그러나 나노 크기의 구조물에서는 표면 효과로 인하여 거시적인 구조물에서와는 매우 상이한 기계적 거동 양상을 띠게 되며 균질화 기법을 나노 크기의 허니콤 구조물에 적용하기 위해서는 이러한 표면 효과를 반영해야만 한다. 본 논문에서는 표면 효과를 고려한 유한 요소를 제안하고 이를 이용하여 나노 크기의 3차원 허니콤 구조물을 균질화 기법을 이용하여 등가의 2차원 판으로 대체하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.4
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• pp.413-419
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• 2011

The nano-size hoenycomb structures have the higher ratio of the surface to the volume than macro-size honeycomb structures, and they can maximize the functionality of the electrical and chemical catalyst. The mechanical behaviors of the nano-sized structures are different from ones of the macro-size structure, and it is caused by the surface effect. This surface effect can be investigated by the atomistic simulation; however, the prediction of mechanical behaviors of the nano-sized honeycombs are practically impossible due to excessive computational resources and computation time. In this paper, by combining the bridging method considering the surface stress elasticity model with homogenization method, the mechanical behaviors of the nano-sized honeycombs are predicted efficiently.

• Composites Research
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• v.37 no.1
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• pp.53-57
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• 2024

Numerous studies have explored structural antennas for integrating advanced wireless systems into aircraft without altering their external form. However, much of the research on structural antennas has focused on patch antennas, which are characterized by limitations such as narrow frequency bands and low directivity. In contrast, the Vivaldi antenna, widely utilized in wireless applications, offers the advantages of a wide frequency band and high directivity. Nevertheless, its application to aircraft has been challenging due to radiation direction constraints. In this study, we endeavor to address this issue by proposing the application of the antenna patch onto the honeycomb wall, thus enabling the use of the Vivaldi antenna on aircraft. The impact of the honeycomb structure on antenna radiation performance was analyzed, and the potential of the honeycomb Vivaldi antenna was validated through simulation.

• Journal of the Korean Society for Railway
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• v.11 no.1
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• pp.1-6
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• 2008

Sound transmission characteristics are investigated on the test specimen for the railway vehicle's floor section. Transmission loss on the honeycomb structure has been examined experimentally with the reverberation chamber. Predicted transmission loss values using NASTRAN, AUTOSEA2, are compared with measured Haloes and the effect of resonance on the transmission loss is identified. Transmission loss of different shapes of honeycomb structure are predicted.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.18-25
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• 2019

Studies on the fabrication of UAV by using 3D printer have been actively carried out. However, research on structural load characteristics in low temperature environment is insufficient. In this study, a composite sandwich structure with ordinary orbs structure was proposed, and the load characteristics for temperature condition changes were analyzed. The ordinary orbs and honeycomb structures were fabricated by using a FDM type 3D printer. The bending load test was carried out at room temperature and low temperature condition. The low temperature condition was classified into four cases. Bending load tests were performed in a low temperature chamber to maintain the required temperature conditions. As a result of the test, it was confirmed that the proposed ordinary orbs structure had better load characteristics at low temperatures than the existing honeycomb structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.697-702
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• 2017

A preliminary study was carried out to investigate the feasibility of replacing honeycomb cores with pyramidal truss cores in the doors of urban transit railway vehicles. The doors in current operation are sandwich structures comprising a honeycomb core and reinforcements between two facesheets. The structural requirements of doors for urban transit vehicle are specified in the KRS and KRT and standards, according to which the deflections from three-point bending tests must be limited. To this end, two types of pyramidal truss cores with equivalent mass to a honeycomb core were designed. The structural stiffness of doors with pyramidal truss cores and honeycomb cores were numerically calculated via finite element analysis. The three-point bending models were constructed and simulated, and then the calculated deflections were compared with the requirements specified in the regulations. The results show that doors with pyramidal truss cores satisfied the stiffness requirements, although their deflections were 2.5% larger than that of the honeycomb cores. Therefore, the pyramidal truss cores could replace the aluminum honeycomb cores, and their multi-functional capability could be exploited.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.555-563
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• 2012

In earth orbit, a great number of orbital debris move around in extremely high velocity, and they become serious threats to satellites. In this study, smoothed particle hydrodynamics(SPH) is used to analyze the damage of a low earth orbit satellite due to the hypervelocity impact with orbital debris. The damage of honeycomb sandwich panel(HC/SP) used for walls of a satellite is analyzed with respect to impact velocities. For the additional analysis to examine the safety of interior components of the satellite, an attached electronic box and an offset electronic box are considered. As a result of the analysis considering the orbital debris having a probability of collision more than 2% at altitude of 685km, it is shown that the HC/SP can be perforated but only small craters are formed on both the attached electronic box and the offset electronic box.

• Composites Research
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• v.36 no.3
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• pp.230-240
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• 2023

The deployable reflector antenna consists of 24 unit main reflectors, and is mounted on a launch vehicle in a folded state. This satellite reaches the operating orbit and the antenna of satellite is deployed, and performs a mission. The deployable reflector antenna has the advantage of reduce the storage volume of payload of launch vehicle, allowing large space structures to be mounted in the limited storage space of the launch vehicle. In this paper, structural analysis was performed on the main reflector constituting the deployable reflector antenna, and through this, the initial conceptual design was performed. Lightweight composite main reflector was designed by applying a carbon fiber composite and honeycomb core. The laminate pattern and shape were selected as design variables and a design that satisfies the operation conditions was derived. Then, the performance of the lightweight composite reflector antenna was analyzed by performing detailed structural analysis on modal analysis, quasi-static, thermal gradient, and dynamic behavior.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.184-192
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• 2006

Synthetic Aperture Radars(SAR) are used mainly for high-resolution imaging of the terrain. This paper describes the $16{\times}16$ array antenna designed for an X-band, automobile-based SAR(AutoSAR) system. This antenna has the structure of several layers such as radome, radiators, slots, feed network, and honeycomb cores. Each layer is adhesively bonded to meet different combination of structural and electrical design requirements. Using the Strip-Slot-Foam-Inverted-Patch(SSFIP) structure and honeycomb cores, a wide bandwidth and a structural hardness were achieved. Measurement results were compared with simulation results. It was observed that this antenna had a bandwidth of 1.7 GHz, side-lobe levels of less than -20 dB, half-power beamwidth of $5^{\circ}$ and $5^{\circ}$, and gains of 25.0 dBi. The observed results show that the designed array antenna will be applicable to the wideband SAR system.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.74-77
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• 2001

The impact response and damage of CLAS panel was investigated experimentally. The facesheet material used was RO4003 woven-glass hydrocarbon/ceramic and the core material was Nomex honeycomb with a cell size of 3.2mm and a density of 96 kg/$\textrm{m}^{3}$. The shield plane used was RO4003 and 2024-T3 aluminum. Static indentation and impact test was conducted to characterize the type and extent of the damage observed in two CLAS panels, and the performance of antenna used in a wireless LAN system. Correlation of peak contact force, residual indentation and the delamination area shows impact damage of the panel with an aluminum shield plane is larger than that of the panel with RO4003 shield plane, although tile former is more penetration resistant. The damage was observed by naked eye, ultrasonic inspection and cross sectioning. The shape and size of delamination was estimated by ultrasonic inspection, and the area of delamination linearly increases as impact energy increases. The performance of impact damaged antenna was estimated by measuring return loss and radiation pattern.