• 한국통신학회논문지
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• 제26권9B호
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• pp.1226-1235
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• 2001

The convergence analysis of the improved multiplication free adaptive digital filter (IMADF) with a fractionally-spaced equalizer (FSE) to remove the intersymbol interference (ISI) in fast data transmission is presented. The IMADF structure use the one-step predicted filter in the multiplication-free adaptive digital filter (MADF) structure using the DPCM and Sign algorithm. In the experimental results, the IMADF algorithm has reduced the computational complexity by use of only the addition operation without a multiplier. Also, under the condition of identical stationary-state error, it could obtain the stabled convergence characteristic that the IMADF algorithm is almost same as the sign algorithm, but is better than the MADF algorithm. Here, this algorithm has effective characteristics when the correlation of the input signal is highly.

• 융합정보논문지
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• 제11권6호
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• pp.120-130
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• 2021

본 연구는 유아의 자유놀이를 지원하는 융합인재교육(STEAM)기반 스마트 앱 활용 교육 프로그램을 개발하고 이의 효과를 검증하기 위한 목적으로 실시되었다. 연구의 목적을 달성하기 위하여 관련 분야 문헌 및 자료수집, 현장조사를 통하여 유아의 자유놀이에 STEAM기반 스마트 앱을 활용하기 위한 내용을 도출하고, 이에 기반하여 프로그램을 개발하였다. 본 프로그램은 스마트 폰에 개발된 'Free Play' 앱을 설치하고 자유놀이 시작, 중간, 종료 단계에서 유아의 놀이에 대해 교사와 유아가 상호작용하는 교수전략이다. 이러한 유아의 자유놀이를 지원하는 스마트 앱 활용 교육 프로그램의 효과를 검증하기 위하여 실험연구를 실시하였다. 연구결과, 본 프로그램의 적용으로 유아의 자기조절력과 자기조절력 하위요인이 향상됨을 확인하였다. 본 연구는 유아교육의 핵심인 자유놀이 시간에 교사와 유아 모두를 지원하기 위한 교수전략이자 공학과 교육이 융합된 발상으로 프로그램을 개발하고 적용하였으며 추후 교육현장에서 스마트 앱 활용 교육을 활성화하는 단초가 되길 기대한다.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.117-121
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• 2018

Perovskite solar cells have received increasing attention in recent years because of their outstanding power conversion efficiency (exceeding 22%). However, they typically contain toxic Pb, which is a limiting factor for industrialization. We focused on preparing Pb-free perovskite films of Ag-Bi-I trivalent compounds. Perovskite thin films with improved optical properties were obtained by applying an anti-solvent (toluene) washing technique during the spin coating of perovskites. In addition, the surface condition of the perovskite film was optimized using a multi-step thermal annealing treatment. Using the optimized process parameters, $AgBi_2I_7$ perovskite films with good absorption and improved planar surface topography (root mean square roughness decreased from 80 to 26 nm) were obtained. This study is expected to open up new possibilities for the development of high performance $AgBi_2I_7$ perovskite solar cells for applications in Pb-free energy conversion devices.

• 한국지능시스템학회논문지
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• 제15권5호
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• pp.552-559
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• 2005

실시간 순환형 훈련 알고리즘(RTRL)과 같이 경사법에 의해 훈련되는 순환형 뉴럴 네트웍(RNN)은 수렴속도가 매우 느린 단점을 지니고 있다. 이 알고리즘은 또한 오차 역전달 처리과정에서 결코 쉽지 않은 미분 계산을 필요로 한다. 본 논문에서는 완전하게 결합된 RNN의 훈련을 위하여 소위 언센티드 칼만필터라고 불리우는 미분없는 칼만필터 훈련 알고리즘을 시스템의 상태공간 상에서 표현하였다. 미분없는 칼만필터 훈련 알고리즘은 순환형 뉴럴 네트웍 훈련시 미분 계산 없이 매우 빠른 수렴속도와 좋은 추정 성능을 보여준다. 비선형 채널 등화 실험을 통하여 미분 없는 칼만필터 훈련 알고리즘을 이용한 RNN의 성능이 향상되었음을 보였다.

• 식품보건융합연구
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• 제6권6호
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• pp.1-7
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• 2020

We compared the fermentation of 0 to 4 weeks by manufacturing a rapid low salt-fermented seahorse with a commercial Protamex added to the functional food, Hippocampus abdominalis. We studied amino acid composition, content and major amino acids related to flavor during the fermentation process of salt-fermented seahorse. In the enzyme-free group, it showed little change in the content of non-protein nitrogenous compounds, the content of amino acids and degree of hydrolysis. The Protamex enzyme treatment group was rapidly hydrolyzed in one week of ripening, resulting in increased non-protein nitrogenous compounds content, amino acid content and degree of hydrolysis, and minimal changes in the four weeks. The total amino acid contents ratio showed the highest content of glutamic acid in the enzyme additive group, glycine, alanine, which indicates sweet taste, and serine, the content of glycine, alanine, serine, and lysine, indicating sweet taste, has increased significantly over the enzyme-free group. Twenty species of free amino acid in the four-week of salt-fermented seahorse were detected. It detected 43.0% (6 species) in the enzyme-free group and 63.96% (7 species) in the enzyme additive group.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.223-235
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• 2006

By applying the Landau-type transformation, we transform a Stefan problem with nonlinear free boundary condition into a system consisting of a parabolic equation and the ordinary differential equations. Fully discrete finite element method is developed to approximate the solution of a system of a parabolic equation and the ordinary differential equations. We derive optimal orders of convergence of fully discrete approximations in $L_2,\;H^1$ and $H^2$ normed spaces.

• Structural Engineering and Mechanics
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• 제8권6호
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• pp.547-560
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• 1999

In this paper an asymptotic iteration method is adopted to analyze non-linear free vibration of reticulated circular plates composed of beam members placed in two orthogonal directions. For the resulting linear ordinary differential equations in the process of iteration, the power series with rapid convergence has been applied to obtain an analytical solution for non-linear characteristic relation between the amplitude and frequency of the structure. Numerical examples are given, and the phenomena indicating hardening of such structures have been presented for the (immovable or movable) simply-supported and clamped circular plates.

• Journal of Theoretical and Applied Mechanics
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• 제1권1호
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• pp.1-27
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• 1995

In this paper a finite element method for free-surface problems is described. the method is based on two different forms of Hamilton's principle. To test the present computational method two specific wave problems are investigated; the dispersion relations and the nonlinear effect for the well-known solitary waves are treated. The convergence test shows that the present scheme is more efficient than other existing methods, e.g. perturbation scheme.

• Current Photovoltaic Research
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• 제5권2호
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• pp.59-62
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• 2017

Surface texturing is affected the uniformity and size of pyramid with saw mark defect density. To analysis the influence of the saw mark defect density, we textured various si wafer. When the texturing process proceeds without the saw mark removal, silicon wafer of low-saw mark defect density showed small pyramid size of $3.5{\mu}m$ with the lowest average value of the reflectance of 10.6%. When texturing carried out after removal of the saw mark using the TMAH solution, we obtained a reflectance of about 11% and the large pyramid size of $5{\mu}m$. As a result, saw mark wafers showed a better pyramid structure than saw mark-free wafer. This result showed that saw mark can take place more smooth etching by the KOH solution and saw mark-free wafer is determined to be a factor that have a higher reflectance and a large pyramid.

• 한국기계가공학회지
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• 제20권3호
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• pp.53-59
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• 2021

In vibration-free vehicles such as limousine buses, the vibration is minimized by installing an air spring instead of the leaf spring used in the existing freight cars to prevent the damage to the loaded cargo from shocks generated during movement. In the existing vehicles, steel structures support the air spring system. This study was aimed at replacing the steel structures used in the Z-spring by carbon fiber and glass fiber reinforced plastics. In addition, the mechanical properties (elastic modulus, tensile strength, and shear strength) of carbon fiber and glass fiber prepreg were derived using specimens molded with the corresponding prepreg. The final goal was to develop a material lighter than the conventional steel material but with enhanced mechanical properties. Although the CF prepreg exhibited excellent mechanical properties, the production cost was extremely high. To overcome this limitation, hybrid composites with GF prepreg were examined, which are expected to be promising future materials.