In this study, when manufacturing a rectangular plate with a pinhole, the following conclusions were obtained as a result of analyzing the shape characteristics of the unit cell that fills the interior of the plate and the effect of changes in the size of the pinhole on the stress concentration coefficient. 1. The stress value generated in the case of the completely empty model was 13.9 MPa, which is an 18.8% increase in stress compared to the stress value 11.7 MPa generated in the fully filled model. However, since the weight of the empty model is 43.6% lower than that of the filled model, it is believed to be very advantageous in terms of cost. 2. The stress concentration coefficient value is lowest for the solid model and highest for the hollow model at the same d/H value. In other words, you can see that the values are changing within the boxes of the solid model and hollow model. However, the grid matching model is closest to the solid model and the filling rate is as low as 33.4-9.1%, showing the most stable strength when filling empty space.

본 논문에서는 15차 bézier 곡선을 사용하여 기존의 연구보다 더 유연한 빔 형상을 설계하고, 더 넓은 설계 공간에서 최적 설계를 수 행하여 최적의 열전도도를 갖는 빔 형상을 설계한다. 설계 공간이 넓어지면 그 만큼 계산양이 증가하게 되는데, 고차원 변수 공간에서 효율적으로 작동하는 인공신경망을 사용하여 최적 설계를 가속화하여 계산 한계를 극복하였다. 더 나아가 최적의 탄성계수를 갖는 빔의 형상과 비교하였으며 열전도와 탄성학 사이의 수학적 유사성을 이용하여 빔 형상을 설명한다. 본 연구에서는 인공지능을 활용 한 형상 최적설계를 통해 기존의 한계를 뛰어넘는 격자구조의 빔 형상을 제안한다. 먼저, SC(Simple Cubic), BC(Body Centered Cubic) 격자 구조 빔 형상을 bézier 곡선으로 모델링하고 bézier 곡선의 제어점 좌표를 무작위로 설정하여 학습데이터를 확보하였다. NN(Neural Network) 및 GA(Genetic Algorithm)를 통해 우수한 유효 열전도도를 가진 빔 형상을 생성하여 최적의 빔 형상을 설계하였 다. 본 연구를 통해 추후 다양한 열 조건에서 격자구조의 적절한 구조적 해답을 제시할 수 있을 것으로 기대된다.

Reliable, inexpensive, environment-friendly, and durable properties of carbon materials with unique and outstanding photoelectric performance is highly desired for myriad of applications such as catalysis and energy storage. Since lattice modulation is a vital method of surface modification of materials, which form by an external force during the synthesis process, causing the internal compression and stretching, leading to lattice sliding event. In this review, we present a summary of different methods to tailor the lattice modulation in 2D carbon-based materials, including grain/twin boundary, lattice strain, lattice distortion, and lattice defects. This overview highlights the implication control of the diverse morphologies of nanocrystals and how to tailor the materials properties without adding any polymers. The improvement in the performance of 2D carbon materials ranges from the enhancement of charge transport and conductivity, structural stability, high-performance of light absorption capacity, and efficient selectivity promote the future prospect of 2D carbon materials broaden their applications in terms of energy conversion and storage. Finally, some perspectives are proposed on the future developments and challenges on 2D carbon materials towards energy storage applications.

The Ti-6Al-4V lattice structure is widely used in the aerospace industry owing to its high specific strength, specific stiffness, and energy absorption. The quality, performance, and surface roughness of the additively manufactured parts are significantly dependent on various process parameters. Therefore, it is important to study process parameter optimization for relative density and surface roughness control. Here, the part density and surface roughness are examined according to the hatching space, laser power, and scan rotation during laser-powder bed fusion (LPBF), and the optimal process parameters for LPBF are investigated. It has high density and low surface roughness in the specific process parameter ranges of hatching space (0.06–0.12 mm), laser power (225–325 W), and scan rotation (15°). In addition, to investigate the compressive behavior of the lattice structure, a finite element analysis is performed based on the homogenization method. Finite element analysis using the homogenization method indicates that the number of elements decreases from 437,710 to 27 and the analysis time decreases from 3,360 to 9 s. In addition, to verify the reliability of this method, stress–strain data from the compression test and analysis are compared.

A timber lattice roof, which has around 30m span, was constructed. In order to figure out the realistic buckling load level, the structural analysis of this roof structure was performed especially by stiffness of connection with various asymmetric snow load. Due to the characteristics of application of snow load, the load combinations of snow should be considered not only global area but also local part so that the critical buckling load could be observed as easy as possible. Geometrical imperfection was simulated to consider inaccurate shape of structure. And then nonlinear analysis were performed. Finally, this paper could investigate that the asymmetric snow load with the lower level stiffness of connection decreased the level of buckling load significantly.

A single-layerd steel lattice roof, which has 50m span, was constructed. In order to figure out the realistic buckling load level, the structural analysis of this roof structure was performed especially by local snow load. Due to the characteristics of application of snow load, the load combinations of snow should be considered not only global area but also local part so that the critical buckling load could be observed as easy as possible. Geometrical imperfection was simulated to consider inaccurate shape of structure. And then nonlinear analysis were performed. Finally, this paper could investigate that the local snow load with geometrical imperfection decreased the level of buckling load significantly.

Solar cells have been more intensely studied as part of the effort to find alternatives to fossil fuels as power sources.The progression of the first two generations of solar cells has seen a sacrifice of higher efficiency for more economic use ofmaterials. The use of a single junction makes both these types of cells lose power in two major ways: by the non-absorptionof incident light of energy below the band gap; and by the dissipation by heat loss of light energy in excess of the band gap.Therefore, multi junction solar cells have been proposed as a solution to this problem. However, the 1st and 2nd generation solarcells have efficiency limits because a photon makes just one electron-hole pair. Fabrication of all-silicon tandem cells using anSi quantum dot superlattice structure (QD SLS) is one possible suggestion. In this study, an SiOx matrix system was investigatedand analyzed for potential use as an all-silicon multi-junction solar cell. Si quantum dots with a super lattice structure (Si QDSLS) were prepared by alternating deposition of Si rich oxide (SRO; SiOx (x=0.8, 1.12)) and SiO2 layers using RF magnetronco-sputtering and subsequent annealing at temperatures between 800 and 1,100oC under nitrogen ambient. Annealing temperaturesand times affected the formation of Si QDs in the SRO film. Fourier transform infrared spectroscopy (FTIR) spectra and x-rayphotoelectron spectroscopy (XPS) revealed that nanocrystalline Si QDs started to precipitate after annealing at 1,100oC for onehour. Transmission electron microscopy (TEM) images clearly showed SRO/SiO2 SLS and Si QDs formation in each 4, 6, and8nm SRO layer after annealing at 1,100oC for two hours. The systematic investigation of precipitation behavior of Si QDsin SiO2 matrices is presented.

왁스 또는 긴사슬을 가지는 탄화수소는 동물, 식물, 광물 또는 합성에 의해 만들어 진다. 오일-왁스 겔은 립스틱과 같은 다양한 화장품 분야에 사용되어지고 있다. 예를 들면, 립스틱의 사용감촉은 오일-왁스 겔의 광택 정도에 크게 영향을 받는다. 여러 논문에서 단일 용매 또는 혼합된 용매에서의 왁스 구조에 대해서 연구가 진행되었다. 그러나 왁스 구조에 대한 연구 논문은 극히 소수에 불과하다. 이 논문의 목적은 세레신 왁스와 또 다른 왁스를 사용하여 오일-왁스겔에서의 광택과 왁스 구조에 대한 관계를 연구하였다. 최근 들어 입술피부에서의 광택 효과는 아름다움의 척도로 알려지고 있다. 광택효과는 오일-왁스 메트릭스가 형성될 때 메트릭스 구조의 변화와 오일의 성질에 의해 좌우된다. 최근 연구에서는 세레신 왁스와 마이크로크리스탈린 왁스로부터 얻어진 오일-왁스 겔에서의 왁스 구조변화와 그에 따른 광택에 대한 영향을 보고하고 있다.