• 한국정밀공학회지
• /
• 제28권7호
• /
• pp.814-820
• /
• 2011

It takes long time in numerical simulation because structural design for tire requires the nonlinear material property. Neural networks has been widely studied to engineering design to reduce numerical computation time. The numbers of hidden layer, hidden layer neuron and training data have been considered as the structural design variables of neural networks. In application of neural networks to optimize design, there are a few studies about arrangement method of input layer neurons. To investigate the effect of input layer neuron arrangement on neural networks, the variables of tire contour design and tension in bead area were assigned to inputs and output for neural networks respectively. Design variables arrangement in input layer were determined by main effect analysis. The number of hidden layer, the number of hidden layer neuron and the number of training data and so on have been considered as the structural design variables of neural networks. In application to optimization design problem of neural networks, there are few studies about arrangement method of input layer neurons. To investigate the effect of arrangement of input neurons on neural network learning tire contour design parameters and tension in bead area were assigned to neural input and output respectively. Design variables arrangement in input layer was determined by main effect analysis.

• 한국컴퓨터정보학회논문지
• /
• 제16권8호
• /
• pp.39-47
• /
• 2011

다층퍼셉트론의 계층별 학습 방법의 하나인 Ergezinger 방법은 출력 노드가 1개로 구성되어 있고, 출력층의 가중치를 최소자승법으로 학습하기 때문에 출력층의 가중치에 조기포화 현상이 발생할 수 있다. 이런 조기 포화현상은 학습 시간과 수렴 속도에 장애가 된다. 따라서, 본 논문은 Ergezinger의 학습 방법을 출력층에서 벡터 형태로 학습할 수 있는 알고리즘으로 확대하고 학습 시간과수렴 속도를 개선하기 위해서 학습 상수를 도입한다. 학습상수는 은닉층 가중치 조정 시, 새로이 계산된 가중치와 기존 가중치의 상관 관계를 계산하여 학습 상수에 반영하는 가변적인 방법이다. 실험은 제안된 방법과 기존 방법의 비교를 위해서 iris 문제와 비선형 근사화 문제를 대상으로 실험하였다. 실험에서, 제안 방법은 기존 Ergezinger 방법보다 학습 시간과 수렴 속도에서 우수한 결과를 얻었으며, 상관 관계를 고려한 CPU time 측정에서도 제안한 방법이 기존 방법보다 약 35%의 시간을 절약할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.1039-1042
• /
• 2001

A method for designing antireflection (AR) and antistatic (AS) films by the use of conducting polymer as an electrically conductive transparent layer is proposed. The conducting AR film is composed of four-layer with alternating high and low refractive index layer: silicon dioxide (n=1.44) and titanium dioxide (n=2.02) prepared at low temperature by sol-gel method are used as the low and high refractive index layer, respectively. The 3,4-polyethylenedioxythiophene (PEDOT) which has the sheet resistance of 10$^4$$\Omega$/$\square$ is used as a conductive layer. Optical constant of ARAS film was measured by the spectroscopic ellipsometer and from the measured optical constants the spectral properties such as reflectance and transmittance were simulated in the visible region. The reflectance of ARAS films on glass substrate was below 0.8 %R and the transmittance was higher than 95 % in the visible wavelength (400-700 nm). The measured AR spectral properties was very similar to its simulated results.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제55권10호
• /
• pp.492-498
• /
• 2006

A novel surface plasmon resonance(SPR) multisensing method, which does not require imaging apparatus such as CCD, has been proposed and implemented experimentally. The proposed method is based on the multichannel SPR and the separation of signals by use of additional layers whose thickness is controlled. SPR signals are influenced by the thickness of sensing layer as well as the optical condition of sensing surface. As the SPR signals from different ligands are usually positioned closely, the reflected light from sensing surface does not provide us with the clear differences of resonance signal depending on the kinds of ligands. It was found from our experiments that SPR signals from each ligand that is located on the additional layer with different thickness can be separated clearly enough to identify various signals from different ligands. Proposed method with theoretical design and simulation has been verified experimentally by using $SiO_2$ thin film layer as additional layer.

• ETRI Journal
• /
• 제36권4호
• /
• pp.564-571
• /
• 2014

Sphere decoding (SD) for multiple-input and multiple-output systems is a well-recognized approach for achieving near-maximum likelihood performance with reduced complexity. SD is a tree search process, whereby a large number of nodes can be searched in an effort to find an estimation of a transmitted symbol vector. In this paper, a simple and generalized approach called layer pruning is proposed to achieve complexity reduction in SD. Pruning a layer from a search process reduces the total number of nodes in a sphere search. The symbols corresponding to the pruned layer are obtained by adopting a QRM-MLD receiver. Simulation results show that the proposed method reduces the number of nodes to be searched for decoding the transmitted symbols by maintaining negligible performance loss. The proposed technique reduces the complexity by 35% to 42% in the low and medium signal-to-noise ratio regime. To demonstrate the potential of our method, we compare the results with another well-known method - namely, probabilistic tree pruning SD.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.119-121
• /
• 2002

$Bi_2Sr_2CuO_x$ thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method, 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
• /
• pp.208-211
• /
• 2002

$Bi_2Sr_2CuO_x$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• 한국수소및신에너지학회논문집
• /
• 제20권6호
• /
• pp.485-491
• /
• 2009

In present work, NiO/YSZ anode functional layer was prepared by nano NiO powder and 8YSZ powder. The nano NiO powders were made by Pulsed wire evaporation (PWE) method. Nano NiO- YSZ functional layer was sintered at the temperature of $900-1400^{\circ}C$. The prepared functional layer was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. The nano NiO- YSZ anode functional layer sintered at $1300^{\circ}C$ shows the lowest polarization resistance. Nano NiO- YSZ anode functional layer shows about two times smaller polarization resistance than the anode functional layer made by commercial NiO-YSZ powders. Based on these experimental results, it is concluded that the nano NiO-YSZ cermet is suitable as a anode functional layer operated at $800^{\circ}C$.

• Transactions on Electrical and Electronic Materials
• /
• 제8권4호
• /
• pp.182-187
• /
• 2007

The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about $205C/m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}=2.5V$, while the positively charged density became the maximum, about $61.1C/m^3$ at the region where it was located around the cathode layer. The performance of the best sample was found to be better in terms of the charge density (Cs) and specific energy ($E_s$) with a maximum value of ${\sim}8.4F/g$ and 26 Wh/kg. The $C_s$ obtained from the PEA method agreed well with that from the energy conversion method. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

• 한국소음진동공학회논문집
• /
• 제16권7호
• /
• pp.690-696
• /
• 2006

Thickness of damping layer in sandwich plate needs to be optimized in order to make modal loss factor of the sandwich plate maximum. Since previous studies were interested in noise reductions over high frequency range, the modal properties were derived based on simply supported boundaries. This conventional formula is approximately applicable to other boundary conditions over high frequency range only. The purpose of this study is to propose a method to determine optimum damping layer thickness of sandwich plate for maximum modal damping in low frequency range when the boundary condition is not a simple support. The conventional RKU equation based on simply supported boundary is modified to reflect other boundary conditions and the modified RKU equation is subsequently applied to determine the optimum damping layer thickness for arbitrary conditions. In order to reflect frequency-dependent characteristics of elastic modulus of the damping layer, an iteration method is proposed in determining the modal properties. Test results on sandwich plates for optimum damping layer thickness are compared with predictions by the proposed method and conventional method.