• Structural Engineering and Mechanics
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• 제70권6호
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• pp.703-710
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• 2019

While fiber-reinforced plastic (FRP) materials have been largely used in the retrofitting of concrete buildings, its application has been limited because of some problems such as de-bonding of FRP layers from the concrete surface. This paper is the part of a wide experimental and analytical investigation about flexural retrofitting of reinforced concrete (RC) columns using FRP and mechanical fasteners (MF). A new generation of MF is proposed, which is applicable for retrofitting of RC columns. Furthermore, generally, to evaluate a retrofitted structure the nonlinear static and dynamic analyses are the most accurate methods to estimate the performance of a structure. In the nonlinear analysis of a structure, accurate modeling of structural elements is necessary for estimation the reasonable results. So for nonlinear analysis of a structure, modeling parameters for beams, columns, and beam-column joints are essential. According to the concentrated hinge method, which is one of the most popular nonlinear modeling methods, structural members shall be modeled using concentrated or distributed plastic hinge models using modeling parameters. The nonlinear models of members should be capable of representing the inelastic response of the component. On the other hand, in performance based design to make a decision about a structure or design a new one, numerical acceptance should be determined. Modeling parameters and numerical acceptance criteria are different for buildings of different types and for different performance levels. In this paper, a new method was proposed for FRP retrofitted columns to avoid FRP debonding. For this purpose, mechanical fasteners were used to achieve the composite behavior of FRP and concrete columns. The experimental results showed that the use of the new method proposed in this paper increased the flexural strength and lateral load capacity of the columns significantly, and a good composition of FRP and RC column was achieved. Moreover, the modeling parameters and acceptance criteria were presented, which were derived from the experimental study in order to use in nonlinear analysis and performance-based design approach.

• 한국통신학회논문지
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• 제27권2A호
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• pp.116-123
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• 2002

자켓 행렬(Jacket matrix)은 왈쉬 하다마드(Walsh Hadamard) 행렬 구조를 바탕으로 확장한 행렬이다. 왈쉬 하다마드 행렬이 +1, -1을 기본 원소로 하고 있는 반면 자켓 행렬은 $\pm$1과 $\pm$$\omega$($\pm$j, $\pm$$_2$$^{n}$ )를 각각 원소로 가질 수 있다. 이 행렬은 중앙 부근에 무게(weight)를 갖는데, 하다마드 행렬 크기의 1/4 크기로 부호 부분과 무게 부분으로 구성된다. 본 논문에서는 기존에 행렬 중앙에 강제적으로 무게를 할당하여 자켓 행렬을 구성하였으나, 어떠한 크기의 행렬도 크기와 무게만 정해주면 생성해낼 수 있는 이진 인덱스를 이용한 간단한 비트열 형태의 일반식이 제시된다. 무게는 행과 열의 이진 인덱스의 최상위 두 비트를 Exclusive-OR 연산한 결과가 1인 원소에 부여된다. 또한 분산연산(Distributed Arithmetic:DA) 알고리즘을 이용한 고속자켓변환(Fast Jacket Transform)의 VLSI 구조를 제시한다. 자켓 행렬은 cyclic한 특성을 가지고 있어서 암호화, 정보 이론 및 WCDMA의 복소수 확산 QPSK 변조부에 응용될 수 있다.

• 한국해양환경ㆍ에너지학회지
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• 제13권1호
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• pp.12-17
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• 2010

OWC 파력발전장치는 에너지 변환장치로 널리 사용되고 있고 공기실의 작동성능을 향상시키기 위하여 파랑집중장치를 고안 하였다. 본 논문에서 사용된 수치조파수조는 two-phase VOF모델을 기반으로 하여 구현되었고 재생된 규칙 입사파는 공기실까지 전달되어 내부의 왕복 유동장을 형성하게 하였다. 수치조파수조는 연속방정식, Reynolds-averaged Navier-Stokes방정식, two-phase VOF 법으로 구성 되였고 standard k- 난류모델, 유한체적법, NITA-PISO 알고리즘 그리고 dynamic mesh기능을 채택하였다. OWC 공기실 파랑집중장치의 성능에 대하여 수치적으로 고찰하였다.

• 한국경영과학회지
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• 제32권4호
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• pp.51-60
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• 2007

In this study, we consider the minimum ADM problem which is the fundamental problem for the cost-effective design of SONET ADM embedded in WDM ring networks. To minimize the number of SONET ADMs, efficient algorithms for the routing and wavelength assignment are needed. We propose a mathematical model based on the graph theory for the problem and propose a branch-and-price approach to solve the suggested model effectively within reasonable time. By exploiting the mathematical structure of ring networks, we developed polynomial time algorithms for column generation subroutine at branch-and-bound tree. In a computer simulation study, the suggested approach can find the optimal solution for sufficient size networks and shows better performance than the greedy heuristic method.

• 산업공학
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• 제23권4호
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• pp.365-371
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• 2010

In this study, we propose a novel remote health monitoring system to accurately predict Parkinson's disease severity using a signomial regression method. In order to characterize the Parkinson's disease severity, sixteen biomedical voice measurements associated with symptoms of the Parkinson's disease, are used to develop the telemonitoring model for early detection of the Parkinson's disease. The proposed approach could be utilized for not only prediction purposes, but also interpretation purposes in practice, providing an explicit description of the resulting function in the original input space. Compared to the accuracy performance with the existing methods, the proposed algorithm produces less error rate for predicting Parkinson's disease severity.

• 한국정보통신학회논문지
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• 제16권1호
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• pp.133-142
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• 2012

본 논문에서는 홀로그램의 기본 원리인 빛의 간섭현상을 수학적 연산을 통하여 획득하는 컴퓨터 생성 홀로그램의 고속 알고리즘을 제안하고, 이를 하드웨어로 구현한다. 컴퓨터 생성 홀로그램을 고속화하기 위하여 연산 식을 변형하여 병렬 연산이 가능하도록 하며, 이를 두 종류의 (초기 연산 셀과 추가 연산 셀) 구조로 하드웨어를 구현한다. 병렬 연산 알고리즘은 홀로그램의 화소 맨 좌측 열의 값만 연산한 후 나머지 열의 화소 값은 모두 동시에 구할 수 있는 알고리즘으로, 초기 연산 셀은 화소 맨 좌측 값을 연산하고, 나머지 열의 값은 추가 연산 셀로 연산하는 방법이다. 최대 동작 주파수는 약 215MHz이었으며, 이 동작 주파수를 기준으로 기존의 방법들 중 가장 우수한 성능을 보이는 방법과 동일하게 환경을 설정하여 실험을 수행하였다. 그 결과 초당 62.9 CGH 프레임을 연산하는 기존의 방법에 비해 제안한 방법은 초당 81.75 CGH 프레임을 연산하여 약 1.3배의 속도가 향상됨을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제35권5호
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• pp.661-666
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• 2011

최근 해양교통시설물의 전력원으로 태양광발전과 파력발전을 이용한 하이브리드 발전 형태에 대한 연구가 진행 중이다. 그러나 해상에서 장기간 해양교통시설물을 운용할 경우 해양교통시설물 수주의 유입구에 해조류 증착 문제가 발생하였다. 이러한 문제의 해결을 위해 AFS (Anti-Fouling System)의 연구가 진행되고 있다. 단일채널 방식의 AFS를 이용하였으나 구리 전극봉의 이온화가 각기 다르게 되어 구리 전극봉의 교환주기를 앞당기는 문제가 발생하였다. 본 논문에서는 다채널 전류제어 방식을 이용한 해양 교통시설물용 AFS를 제안하고 시뮬레이션을 하였다. 시뮬레이션의 신뢰성을 높이기 위하여 실제 해양교통시설물의 전극봉 용해결과를 시뮬레이션 프로그램에 반영하였다. 시뮬레이션 결과 제안된 다채널 전류 제어 방식의 AFS의 전극봉이 균일하게 이온화 되는것을 확인할 수 있었다.

• 한국환경보건학회지
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• 제29권4호
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• pp.27-34
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• 2003

Bisphenol A is used in the manufacture of epoxy, polycarbonate, and corrosion-resistant unsaturated polyester-styrene resins required for food packaging materials in industrial processing. Some reports indicated the possibility of harmful effects on rats. In this study was used a method for the determination of bisphenol A in blood according to the OSHA High Performance Liquid Chromatography (HPLC) guideline. The method involved blood extraction using methylene chloride. And it was evaluated developmental and teratogenic effects in pregnant rats and second generation. The results obtained were as follows. There was a significant increase in the body weights and treated groups F1 female in liver, spleen, kidney, but according to dose-response. F1 female rat's relative body weight and absolute body weight are not different. There was a significant increase liver, spleen, kidney organ weight and reproductive organ weight epididymis, prostate gland in F1 male rats. There was a proestrous in pregnant rat, group 200 $\mu\textrm{g}$/kg, 2000 $\mu\textrm{g}$/kg, 20,000 $\mu\textrm{g}$/kg. The effect on rat treated with bisphenol A decrease organ weight and reproductive organ weight. Identification and quantitation were performed with using HPLC C18 column and using at retention time 5.5 min. The results of the detection of bisphenol A were at 20,000 $\mu\textrm{g}$/kg in average 1 $\mu\textrm{g}$/ml, 200 $\mu\textrm{g}$/kg average in 0.9 $\mu\textrm{g}$/ml blood samples. From those results, it could be concluded that the effects of pregnant rat and second generation(F1) by bisphenol A treatment during lactational period were estrogenic and bisphenol A was remained in serum at low level.

• Interaction and multiscale mechanics
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• 제1권2호
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• pp.231-250
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• 2008

The statistical two-order and two-scale method is developed for predicting the mechanics parameters, such as stiffness and strength of core-shell particle-filled polymer composites. The representation and simulation on meso-configuration of random particle-filled polymers are stated. And the major statistical two-order and two-scale analysis formulation is briefly given. The two-order and two-scale expressions for the strains and stresses of conventionally strength experimental components, including the tensional or compressive column, the twist bar and the bending beam, are developed by means of their classical solutions with orthogonal-anisotropic coefficients. Then a new effective mesh generation algorithm is presented. The mechanics parameters of core-shell particle-filled polymer composites, including the expected stiffness parameters, minimum stiffness parameters, and the expected elasticity limit strength and the minimum elasticity limit strength, are defined by means of the stiffness coefficients and elasticity strength criterions for core, shell and matrix. Finally, the numerical results for predicting both stiffness and elasticity limit strength parameters are compared with the experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.366-371
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• 2007

In many CAD systems, NURBS has been employed to construct exact geometries. Recently, NURBS finite element analysis methods were proposed by some authors for convenient connection between CAD and finite element analysis. Additional advantages of NURBS FEA, such as exact geometry and no mesh generation, are obtained. However, NURBS is inefficient in local refinement and merging patches. For refinement of local region in interest, additional control points should be inserted into the entire row or column which contains the local region. There is another inefficiency of NURBS during merging patches into a large structure due to propagation of control points. In order to overcome these inefficiencies of NURBS, T-spline was proposed by Sederberg. In this work, T-spline based finite element method is proposed for efficient local refinement and merging patches. At first, accuracy and efficiency of NURBS FEA is verified and efficiency of T-spline FEA is verified by comparing with NURBS FEA.