In general, a large mirror without weight reduction in large optical or space telescope systems can increase the system’s weight or lead to significant deformation of the mirror surface. Thus, it is imperative to pursue lightweight design strategies. In this paper, the structure design of a spherical mirror, a diameter of 600mm and a mirror radius of 2,000mm, was investigated to reduce weight and minimize deformation. To establish load paths for internal and external loads, stiffeners were added across the lateral supports. This approach effectively reduced both weight and deformation caused by gravity. Weight reduction and reduction percentages were quantified, and the mirror deformation was evaluated by using finite element analysis (FEA). The proposed structures were compared with honeycomb structures for weight reduction. This evaluation allowed to assess the deformation characteristics and the potential advantages of the proposed structures for lightweight mirrors.

Zerodur, one of the optical materials, was used for large spherical mirrors in this study. For weight reduction, several types of honeycomb structures were investigated. The finite element simulation was used for deformation and mode analysis. It was revealed that the weight reduction rate and maximum deflection due to the gravity effect vary depending on the honeycomb structures. Additionally, this study highlights the potential of spline-shaped honeycomb structures as an alternative for weight reduction, and triangular honeycomb structures demonstrated the less deformation by the gravity effect. The findings from this study provide valuable insights for designing lightweight and high-performance spherical mirrors in optical systems.

The objective of this study is to analysis the seismic response of 200m spanned honeycomb lattice domes under horizontal and up-down ground motion of El Centro earthquake. For the analysis of seismic response of the honeycomb lattice domes by rise/span ratio, the time history analysis is used for the estimation of the dynamic response. The low rise lattice dome is less deformed and less stressed than the high rise lattice dome for the earthquake ground motion. The 3-dimensional earthquake response is not significantly different the dynamic response of one directional ground motion. The earthquake response of domes with LRB isolation system is significantly reduced for the asymmetric vertical deformation and the horizontal and vertical accelerations.

현재 해양플랜트용 패널의 주요한 중심재는 다공성재료(미네랄울) 이지만, 뛰어난 차음성능에도 불구하고 환경적인 이유로 이 를 대체할 재료가 요구되고 있다. 허니컴 구조는 무게 대비 강도가 우수하여 산업전반에서 많이 쓰이고 있다. 하지만 소음진동 측면에서의 연구는 미미하다. 다공성재료를 대체하기 위한 연구로서 허니컴의 음향학적 연구가 필요하다. 본 논문에서는 허니컴패널을 대칭모드와 비 대칭모드의 중첩으로 가정하여 수치해석을 진행하였다. 이러한 이론을 통한 수치해석과 실험결과를 비교하여 수치해석의 신뢰성을 검증 하였다. 그리고 수치해석을 통해 허니컴패널의 차음특성을 연구하고 중심재로서의 가능성을 평가하였다. 패널두께를 키울수록 일치주파 수가 저주파수로 이동하였다. 셀사이즈와 셀벽의 사이각이 감소함에 따라 차음성능이 개선되었고, 셀벽두께의 경우 증가할수록 차음성능 이 향상되었다.

A simulation method to estimate microstructure dependent material properties and their influence on performance for a honeycomb structured SiC heating element has been established. Electrical and thermal conductivities of a porous SiC sample were calculated by solving a current continuity equation. Then, the results were used as input parameters for a finite element analysis package to predict temperature distribution when the heating element was subjected to a DC bias. Based on the simulation results, a direction of material development for better heating efficiency was found. In addition, a modified metal electrode scheme to decelerate corrosion kinetics was proposed, by which the durability of the water heating system was greatly improved.

본 연구에서는 허니컴 패널의 지배방정식을 이용하여 경계행렬식을 유도하였고, 이를 전달행렬법에 적용하여 허니컴 패널을 적용한 차음패널에 대한 해석 이론을 정립하였다. 또한, 허니컴 패널을 선박용 차음패널의 표면재로 적용하여 차음성능을 분석하였고, 철판을 표면재로 적용한 기존의 선박용 차음패널과 차음성능을 무게 당 감음량 기준으로 비교 분석하였다. 그 결과, 허니컴 패널의 차음성능이 0.35 mm 철판에 비해 STC 기준으로 2dB 높게 나와 허니컴 패널을 적용한 차음패널의 차음성능이 철판을 사용한 차음패널에 비해 무게 당 감음량을 고려할 시 우수하다는 것을 확인하였다. 또한, 허니컴 패널을 표면재로 사용한 차음패널의 면밀도가 철판을 사용한 차음패널에 비해 약 5.2 kg/㎡ 가볍게 나타났고, 이는 약 31.7 % 무게 감소를 의미한다.

In this study, the impact properties of aluminum honeycomb core composite are investigated through simulation analysis. The specimens are applied with different impact energies of 50 J, 70 J, and 100 J. The maximum load occurs at 3.7 ms for 50 J, 3.7 ms for 70 J and 2.3 ms for 100 J. The maximum load occurs when the striker is penetrating the upper face sheet in all cases. In case of 50 J impact energy, striker does not penetrate the lower face sheet and honeycomb core sandwich can be stable as the energy of 38 J happens. In case of 70 J impact energy, the striker penetrates into the specimen. The striker then causes the damage to the lower face sheet after penetrating the upper face sheet and the core as the energy of 53 J happens. In case of 100 J impact energy, the striker penetrates through all of the upper face sheet, core and lower face sheet as the energy of 65 J happens. This study can be utilized at the design of aluminum honeycomb core sandwich composite structure by understanding stability through the impact property.

The rheological behavior of a cordierite honeycomb extrusion paste was investigated by measuring torque values in a Brabender plastograph. The extrusion pastes were formulated using binder (methy cellulose, MC), solvent (water), plasticizer (ploy ethylene glycol, PEG) and lubricants (oleic acid, OA). The mixing sequence and optimum organic binder, at least for homogeneous mixed state, can be determined from the rheological point of view. 3%MC-30%-1.5%PEG-1.0%OA with respect to the cordierite powder was chosen as a binder composition for the extrusion process of cordierite powder.