• 한국인터넷방송통신학회논문지
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• 제8권6호
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• pp.153-157
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• 2008

최근 산업사회에서 널리 쓰이는 전자소자들은 다층구조로 제작되고 있는 실정이며 이러한 소자의 보이지 않는 층에 대한 해석은 비파괴 검사에서 중요한 일이다. 따라서 본 논문에서는 접착층이 존재하는 다층구조물에 초음파를 입사시켰을 때 반사되는 신호를 디지털 신호처리하여 가시도를 개선하였다. 이를 위하여 다층구조물에서 반사된 신호를 전력 켑스트럼 처리하여 각층에서 나타난 첫 번째 피크와 두 번째 피크를 구할 수 있었다. 실험을 위하여 일정한 두께를 갖는 에폭시층이 존재하는 다층구조물을 형성하였고 초음파 펄스-에코 방법에 의하여 얻어진 반사신호의 가시도를 개선하기 위해 전력 켑스트럼 처리하였다.

• 한국수소및신에너지학회논문집
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• 제12권3호
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• pp.191-199
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• 2001

In this paper molecular dynamics simulations have been carried out to investigate energy and momentum transfer of hydrogen ions impacted on the Ni (100) surface with $45^{\circ}$ and $90^{\circ}$ incident angles. The initial kinetic energies of the hydrogen ion were ranged from 100 eV to 1,600 eV to study the layer-by-layer energy variation as a dependence of incident energies and angles. At low incident energies, the scattering energy transfer is dominated by the normal motion of surface layers due to thermal vibrations and multiple collision effects. For higher incident energies, the scattering energy transfer in a normal direction is greater than that in a parallel direction. In the case of penetration, the amount of transferred energies do not affect much on Ni layers at low incident energy. It was found channeling effects through Ni layers with increasing incident energies.

• Journal of Communications and Networks
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• 제14권5호
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• pp.554-565
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• 2012

In this paper, we study a cross-layer and end-to-end optimization problem for the integrated wireless and wireline network that consists of one wireline core network and multiple wireless access networks. We consider joint end-to-end flow control/distribution at the transport and network layers and opportunistic scheduling at the data link and physical layers. We formulate a single stochastic optimization problem and solve it by using a dual approach and a stochastic sub-gradient algorithm. The developed algorithm can be implemented in a distributed way, vertically among communication layers and horizontally among all entities in the network, clearly showing what should be done at each layer and each entity and what parameters should be exchanged between layers and between entities. Numerical results show that our cross-layer and end-to-end optimization approach provides more efficient resource allocation than the conventional layered and separated optimization approach.

• Structural Engineering and Mechanics
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• 제67권3호
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• pp.277-281
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• 2018

The analytical solution of two functionally graded layers with Volterra type screw dislocation is investigated under anti-plane shear impact loading. The energy dissipation of FGM layers is modeled by viscous damping and the properties of the materials are assumed to change exponentially along the thickness of the layers. In this study, the rate of gradual change ofshear moduli, mass density and damping constant are assumed to be same. At first, the stress fields in the interface of the FGM layers are derived by using a single dislocation. Then, by determining a distributed dislocation density on the crack surface and by using the Fourier and Laplace integral transforms, the problem are reduce to a system ofsingular integral equations with simple Cauchy kernel. The dynamic stress intensity factors are determined by numerical Laplace inversion and the distributed dislocation technique. Finally, various examples are provided to investigate the effects of the geometrical parameters, material properties, viscous damping and cracks configuration on the dynamic fracture behavior of the interacting cracks.

• 한국정보통신학회논문지
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• 제9권7호
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• pp.1452-1457
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• 2005

QR Decomposition-based (QRD) decoding class에서는, 시스템 성능이 에러 전송에 민감하다. 그러므로 이전의 layer들을 정확하게 디코딩하는 것이 중요하다. 에러 전송에 민감하지 않도록 하는 접근 방법 중의 하나가 layer들의 최적 디코딩 order를 제안하는 것이다. 본 논문에서는 새로운 extended-list Sorted QRD-based (SQRD) 디코딩 접근 방법을 제안한다. 제안되는 디코딩 방법에는 약간의 첫째 layer들의 solution이 상당히 가능성 있는 solution들의 list로 확장된다. 이렇게 함으로 가장 낮은 layer의 diversity가 증가된다. 결과적으로 시스템 성능이 다른 것들의 에러 전송보다 덜 민감하게 된다. 제안되는 방법은 컴퓨터 시뮬레이션 결과로 증명된다.

• Ocean Systems Engineering
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• 제8권4호
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• pp.409-426
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• 2018

This paper presents the strengthening of tubular joint by wrapping Carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP). In this study, total number of layers, stacking sequence and length of wrapping are the different parameters involved when fiber reinforced polymers (FRP) composites are used for strengthening. For this, parameters where varied and results were compared with the reference joint. The best stacking sequence was identified which has the highest value in ultimate load with lesser deflections. For determining the best stacking sequence, numerical investigation was performed on CFRP composites; length of wrapping and number of layers were fixed. Later, the studies were focused on CFRP and GFRP strengthened joint by varying the total number of layers and length of wrapping. An attempt was done to propose a parametric equation from multiple regression analysis, which can be used for CFRP strengthened joints. Hashin failure criteria was used to check the failure of composites. Results revealed that FRP was having a greater influence in the load bearing capacity of joints, and in reducing the deflections and stresses of joint under axial compressive loads. It was also seen that, CFRP was far better than GFRP in reducing the stresses and deflection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1246-1262
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• 2021

Recent studies have demonstrated the strong ability of deep convolutional neural networks (CNNs) to significantly boost the performance in single image super-resolution (SISR). The key concern is how to efficiently recover and utilize diverse information frequencies across multiple network layers, which is crucial to satisfying super-resolution image reconstructions. Hence, previous work made great efforts to potently incorporate hierarchical frequencies through various sophisticated architectures. Nevertheless, economical SISR also requires a capable structure design to balance between restoration accuracy and computational complexity, which is still a challenge for existing techniques. In this paper, we tackle this problem by proposing a competent architecture called Enhanced U-Net Network (EUN), which can yield ready-to-use features in miscellaneous frequencies and combine them comprehensively. In particular, the proposed building block for EUN is enhanced from U-Net, which can extract abundant information via multiple skip concatenations. The network configuration allows the pipeline to propagate information from lower layers to higher ones. Meanwhile, the block itself is committed to growing quite deep in layers, which empowers different types of information to spring from a single block. Furthermore, due to its strong advantage in distilling effective information, promising results are guaranteed with comparatively fewer filters. Comprehensive experiments manifest our model can achieve favorable performance over that of state-of-the-art methods, especially in terms of computational efficiency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.225-226
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• 2014

In multi-story buildings, heavy-weight floor impact noise propagates through multiple layers. In order to evaluate the influence of structural vibration and propagation, the actual twelve-story building was excited by an impact ball. Sound and vibration responses of each floor was measured using accelerometers and a microphone. Vibration characteristics and its transfer paths were different depending on the excitation floor locations due to differences in the structural characteristics. From the measurement result, transfer characteristics were quantified by statistical energy analysis. It was confirmed that the heavy-weight floor impact noise influence not only adjacent floor. The impact noise transferred and affected multiple layers.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.87-90
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• 1990

We compare the reflectivity spectrum and phase change of Bragg reflectors obtained by the matrix method and the coupled wave method. We show that the results obtained by the two methods agree well generally and the discrepancy between the results obtained by the two methods increases as the fractional refractive index difference between adjacent layers increases and/or the absorption loss increases, due to the approximations inherent in the coupled wave method for the analysis of multiple dielectric layers.

• 대한가정학회지
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• 제37권11호
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• pp.157-165
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• 1999

This study was carried out to examine the effect of clothing materials and multi-layered textiles on thermal resistance value. Cotton, polyester, wool, silk, rayon and acetate were selected for the specimens. Thermal resistance value was tested with 2 kinds of methods(thermo labo II and BK type tester). The results were as follows; 1. The effects of clothing materials for thermal resistance value were decreased by adding layers. 2. When the fabrics are measured with multiple layers, the fabric of the lowest thermal resistance value at single layer was showed the highest increasing tendency for all test methods.