• Journal of Mechanical Science and Technology
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• 제14권7호
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• pp.789-795
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• 2000

Free-surface flows with an arbitrary deformation, induced by a submerged hydrofoil, are simulated numerically, considering two-fluid flows of both water and air. The computation is performed by a finite volume method using unstructured meshes and an interface capturing scheme to determine the shape of the free surface. The method uses control volumes with an arbitrary number of faces and allows cell wise local mesh refinement. The integration in space is of second order, based on midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation in time through three time levels. The linear equations are solved by conjugate gradient type solvers, and the non-linearity of equations is accounted for through Picard iterations. The solution method is of pressure-correction type and solves sequentially the linearized momentum equations, the continuity equation, the conservation equation of one species, and the equations for two turbulence quantities. Finally, a comparison is quantitatively made at the same speed between the computation and experiment in which the grid sensitivity is numerically checked.

• Advances in nano research
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• 제8권4호
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• pp.283-292
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• 2020

In the present research, differential quadrature (DQ) method has been utilized for investigating free vibrations of porous functionally graded (FG) micro/nano beams in thermal environments. The exact location of neutral axis in FG material has been assumed where the material properties are described via porosity-dependent power-law functions. A scale factor related to couple stresses has been employed for describing size effect. The formulation of scale-dependent beam has been presented based upon a refined beam theory needless of shear correction factors. The governing equations and the associated boundary conditions have been established via Hamilton's rule and then they are solved implementing DQ method. Several graphs are provided which emphasis on the role of porosity dispersion type, porosity volume, temperature variation, scale factor and FG material index on free vibrational behavior of small scale beams.

• Steel and Composite Structures
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• 제19권5호
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• pp.1259-1277
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• 2015

In this work, a trigonometric refined beam theory for the bending, buckling and free vibration analysis of carbon nanotube-reinforced composite (CNTRC) beams resting on elastic foundation is developed. The significant feature of this model is that, in addition to including the shear deformation effect, it deals with only 3 unknowns as the Timoshenko beam (TBM) without including a shear correction factor. The single-walled carbon nanotubes (SWCNTs) are aligned and distributed in polymeric matrix with different patterns of reinforcement. The material properties of the CNTRC beams are assessed by employing the rule of mixture. To examine accuracy of the present theory, several comparison studies are investigated. Furthermore, the effects of different parameters of the beam on the bending, buckling and free vibration responses of CNTRC beam are discussed.

• 한국기계연구소 소보
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• 통권19호
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• pp.93-115
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• 1989

Cerebellar Model Arithmetic Controller(CMAC) has been introduced as an adaptive control function generator. CMAC computes control functions referring to a distributed memory table storing functional values rather than by solving equations analytically or numerically. CMAC has a unique mapping structure as a coarse coding and supervisory delta-rule learning property. In this paper, learning aspects and a convergence of the CMAC were investigated. The efficient training algorithms were developed to overcome the limitations caused by the conventional maximum error correction training and to eliminate the accumulated learning error caused by a sequential node training. A nonlinear function generator and a motion generator for a two d. o. f. manipulator were simulated. The efficiency of the various learning algorithms was demonstrated through the cpu time used and the convergence of the rms and maximum errors accumulated during a learning process; A generalization property and a learning effect due to the various gains were simulated. A uniform quantizing method was applied to cope with various ranges of input variables efficiently.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
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• 한국정보과학회언어공학연구회 2009년도 제21회 한글 및 한국어 정보처리 학술대회
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• pp.231-236
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• 2009

본 논문에서는 통계적으로 추출한 수정규칙을 이용하여 구 기반 한-중 통계기계번역 시스템(PBSMT)의 단어정렬 결과를 개선하는 방법을 제안한다. 논문에서 제안하는 수정규칙은 단어정렬의 결과를 사람이 만든 정답과 비교하여 통계적으로 추출하였다. 본 논문에서는 위에서 추출한 수정규칙을 이용하여 한-중 통계기계번역 시스템의 단어정렬의 결과에서 한국어 기능어(functional word)에 나타나는 오류를 수정함으로써 단어정렬의 결과를 개선하였고 최종적으로 기계번역의 성능을 제고하였다.

• Geomechanics and Engineering
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• 제9권3호
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• pp.361-372
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• 2015

In this paper, a refined exponential shear deformation theory for free vibration analysis of functionally graded beam with considering porosities that may possibly occur inside the functionally graded materials (FGMs) during their fabrication. For this purpose, a new displacement field based on refined shear deformation theory is implemented. The theory accounts for parabolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. Based on the present refined shear deformation beam theory, the equations of motion are derived from Hamilton's principle. The rule of mixture is modified to describe and approximate material properties of the FG beams with porosity phases. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions. Illustrative examples are given also to show the effects of varying gradients, porosity volume fraction, aspect ratios, and thickness to length ratios on the free vibration of the FG beams.

• Advances in materials Research
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• 제9권1호
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• pp.33-48
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• 2020

With the use of differential quadrature method (DQM), forced vibrations and resonance frequency analysis of functionally graded (FG) nano-size beams rested on elastic substrate have been studied utilizing a shear deformation refined beam theory which contains shear deformations influence needless of any correction coefficient. The nano-size beam is exposed to uniformly-type dynamical loads having partial length. The two parameters elastic substrate is consist of linear springs as well as shear coefficient. Gradation of each material property for nano-size beam has been defined in the context of Mori-Tanaka scheme. Governing equations for embedded refined FG nano-size beams exposed to dynamical load have been achieved by utilizing Eringen's nonlocal differential law and Hamilton's rule. Derived equations have solved via DQM based on simply supported-simply supported edge condition. It will be shown that forced vibrations properties and resonance frequency of embedded FG nano-size beam are prominently affected by material gradation, nonlocal field, substrate coefficients and load factors.

• International Journal of Internet, Broadcasting and Communication
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• 제16권3호
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• pp.228-235
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• 2024

Battery use is increasing worldwide to achieve carbon neutrality and improve energy efficiency, but batteries are a finite resource and their application is determined by capacity and specifications. Battery performance deteriorates as the number of uses increases. A certain level of battery performance degradation has become an issue in the field of reuse and recycling, and various studies are being conducted on reuse to solve power shortages. Waste batteries from electric vehicles are suitable for building ESS based on reusable batteries, and for stable use, technical skills are needed to accurately predict battery life and determine status information. Predicting battery life and determining status information are difficult due to non-linearity due to internal structure or chemical changes. In this paper, we manufactured a modular internal resistance measuring device and compared the measured values with Hioki equipment to minimize the error rate through a correction method. As a result of testing Hioki equipment and modular measuring instruments to ensure efficiency and safety based on reusable batteries, an accuracy of over 95% was confirmed.

• Computers and Concrete
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• 제25권6호
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• pp.485-495
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• 2020

This paper, presents the dynamic and stability analysis of the simply supported single walled Carbon Nanotubes (SWCNT) reinforced concrete beam on elastic-foundation using an integral first-order shear deformation beam theory. The condition of the zero shear-stress on the free surfaces of the beam is ensured by the introduction of the shear correction factors. The SWCNT reinforcement is considered to be uniform and variable according to the X, O and V forms through the thickness of the concrete beam. The effective properties of the reinforced concrete beam are calculated by employing the rule of mixture. The analytical solutions of the buckling and free vibrational behaviors are derived via Hamilton's principle and Navier method. The analytical results of the critical buckling loads and frequency parameters of the SWCNT-RC beam are presented in the form of explicit tables and graphs. Also the diverse parameters influencing the dynamic and stability behaviors of the reinforced concrete beam are discussed in detail.

• 한국안광학회지
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• 제8권1호
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• pp.41-45
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• 2003

노인성 백내장의 세 가지 형태학이 굴절이상에 미치는 영향에 관하여 연구하기 위해 세 가지 형태의 백내장 특성에 따른 구면 굴절력과 원주 굴절력의 변화를 백내장의 형태적인 위치에서 나타내었고 또한 백내장 수술 전후의 안압이 굴절이상에 어떠한 영향을 주는가에 대하여 연구하였다. 등가 구면 굴절력에서 핵 백내장은 근시성 전환, 피질 백내장은 원시성 전환을 보였고 낭 백내장은 양쪽의 전환 폭이 적은 것으로 나타났다. 수정체 내 백액내장의 해부학적 위치를 확인하기 위해 광학단면(세극등)을 이용하여 관찰하였고 굴절이상을 측정하기 위해 타각적, 그리고 자각적 방법을 사용하여 등가 구면 굴절력으로 나타내었다. 안압 측정은 수술전과 수술 후 인공수정체가 삽입된 일주일 뒤에 다사 각각의 상태에서 안압을 자동 안압계를 사용하여 측정하였다. 원주 굴절력의 변화는, 일반적으로 나이가 증가함에 따라 안축의 길이가 감소하는 경향을 보였지만, 백내장의 진행으로 안압이 높아져 안축의 길이가 증가하게되고 그 영향으로 직난시에서 도난시로의 전환에 영향을 주기도 하고 또한 이것이 안압으로 인해 더욱 증가하기도 함을 알 수 있었다.