• Structural Engineering and Mechanics
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• 제57권3호
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• pp.569-585
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• 2016

This paper highlights a case study that investigates the behaviour of existing bridge, West Terrace Bridge, induced by horizontal seismic loading. Unfortunately the lack of past information related to seismic activity within the NSW region has made it difficult to understand better the capacity of the structure if Earthquake occurs. The research was conducted through the University of Western Sydney in conjunction with Railcorp Australia, as part of disaster reduction preparedness program. The focus of seismic analyses was on the assessment of stress behaviour, induced by cyclic horizontal/vertical displacements, within the concrete slab and steel truss of the bridge under various Earthquake Year Return Intervals (YRI) of 1-100, 1-200, 1-250, 1-500, 1-800, 1-1000, 1-1500, 1-2000 and 1-2500. Furthermore the stresses and displacements were rigorously analysed through a parametric study conducted using different boundary conditions. The numerical analysis of the concrete slab and steel truss were performed through the finite element software, ABAQUS. The field measurements and observation had been used to validate the results drawn from the finite element simulation. It was illustrated that under a YRI of 1/1000 the bottom chord of the steel truss failed as the stress induced surpassed the ultimate stress capacity and the horizontal displacement exceeded the allowable displacement measured in the field observations whereas the vertical displacement remained within the previously observed limitations. Furthermore the parametric studies in this paper demonstrate that a change in boundary conditions alleviated the stress distribution throughout the structure allowing it to withstand a greater load induced by the earthquake YRI but ultimately failed when the maximum earthquake loading was applied. Therefore it was recommended to provide a gap of 50mm on the end of the concrete slab to allow the structure to displace without increasing the stress in the structure. Finally, this study has proposed a design chart to showcase the failure mode of the bridge when subjected to seismic loading.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.169-172
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• 2008

Land-use or land-cover classification of satellite images is one of the important tasks in remote sensing application and many researchers have been tried to enhance classification accuracy. Previous studies show that the classification technique based on wavelet transform is more effective than that of traditional techniques based on original pixel values, especially in complicated imagery. Various wavelets can be used in wavelet transform. Wavelets are used as basis functions in representing other functions, like sinusoidal function in Fourier analysis. In these days, some basis functions such as Haar, Daubechies, Coiflets and Symlets are mainly used in 2D image processing. Selecting adequate wavelet is very important because different results could be obtained according to the type of basis function in classification. However, it is not easy to choose the basis function which is effective to improve classification accuracy. In this study, we computed the wavelet coefficients of satellite image using 10 different basis functions, and then classified test image. After evaluating classification results, we tried to ascertain which basis function is the most effective for image classification. We also tried to see if the optimum basis function is decided by energy parameter before classifying the image using all basis function. The energy parameter of signal is the sum of the squares of wavelet coefficients. The energy parameter is calculated by sub-bands after the wavelet decomposition and the energy parameter of each sub-band can be a favorable feature of texture. The decision of optimum basis function using energy parameter in the wavelet based image classification is expected to be helpful for saving time and improving classification accuracy effectively.

• Earthquakes and Structures
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• 제14권2호
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• pp.103-115
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• 2018

In this work, a simple but accurate hyperbolic plate theory for the free vibration analysis of functionally graded material (FGM) sandwich plates is developed. The significant feature of this formulation is that, in addition to including the shear deformation effect, it deals with only 3 unknowns as the classical plate theory (CPT), instead of 5 as in the well-known first shear deformation theory (FSDT) and higher-order shear deformation theory (HSDT). A shear correction factor is, therefore, not required. Two common types of FGM sandwich plates are considered, namely, the sandwich with the FGM face sheet and the homogeneous core and the sandwich with the homogeneous face sheet and the FGM core. The equation of motion for the FGM sandwich plates is obtained based on Hamilton's principle. The closed form solutions are obtained by using the Navier technique. The fundamental frequencies are found by solving the eigenvalue problems. Numerical results of the present theory are compared with the CPT, FSDT, order shear deformation theories (HSDTs), and 3D solutions. Verification studies show that the proposed theory is not only accurate and simple in solving the free vibration behaviour of FGM sandwich plates, but also comparable with the higher-order shear deformation theories which contain more number of unknowns.

• 대한수학회지
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• 제55권6호
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• pp.1381-1388
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• 2018

Let ${\Delta}$ be a simplicial complex, $I_{\Delta}$ its Stanley-Reisner ideal and $K[{\Delta}]$ its Stanley-Reisner ring over a field K. Assume that ${\Gamma}(R)$ denotes the zero-divisor graph of a commutative ring R. Here, first we present a condition on two reduced Noetherian rings R and R', equivalent to ${\Gamma}(R){\cong}{\Gamma}(R{^{\prime}})$. In particular, we show that ${\Gamma}(K[{\Delta}]){\cong}{\Gamma}(K^{\prime}[{\Delta}^{\prime}])$ if and only if ${\mid}Ass(I_{\Delta}){\mid}={\mid}Ass(I_{{{\Delta}^{\prime}}}){\mid}$ and either ${\mid}K{\mid}$, ${\mid}K^{\prime}{\mid}{\leq}{\aleph}_0$ or ${\mid}K{\mid}={\mid}K^{\prime}{\mid}$. This shows that ${\Gamma}(K[{\Delta}])$ contains little information about $K[{\Delta}]$. Then, we define the squarefree zero-divisor graph of $K[{\Delta}]$, denoted by ${\Gamma}_{sf}(K[{\Delta}])$, and prove that ${\Gamma}_{sf}(K[{\Delta}){\cong}{\Gamma}_{sf}(K[{\Delta}^{\prime}])$ if and only if $K[{\Delta}]{\cong}K[{\Delta}^{\prime}]$. Moreover, we show how to find dim $K[{\Delta}]$ and ${\mid}Ass(K[{\Delta}]){\mid}$ from ${\Gamma}_{sf}(K[{\Delta}])$.

• 응용통계연구
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• 제33권5호
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• pp.569-578
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• 2020

분위수 회귀모형은 반응변수의 조건부 분위수 함수를 추정함으로써 반응변수와 예측변수의 관계에 대한 포괄적인 정보를 제공한다. 특히 커널 분위수 회귀모형은 비선형 관계식을 고려하기 위하여 양정치 커널함수(kernel function)에 의해 만들어지는 재생 커널 힐버트 공간(reproducing kernel Hilbert space)에서 비선형 조건부 분위수 함수를 추정한다. 그러나 KQR은 이차계획법으로 공식화되어 많은 계산비용을 필요로 하므로 컴퓨터 메모리 능력의 제한으로 대용량 자료의 분석은 불가능하다. 이러한 문제점을 해결하기 위하여 본 논문에서는 분할정복(divide and conquer) 알고리즘을 활용한 KQR 추정법(DC-KQR)을 제안한다. DC-KQR은 먼저 전체 훈련자료를 몇 개의 부분집합으로 무작위로 분할(divide)한 후, 각각의 부분집합에 대하여 KQR 분위수 함수를 추정하고 이들의 산술 평균을 이용하여 최종적인 추정량으로 통합(conquer)하는 기법이다. 본 논문에서는 모의실험과 실제자료 분석을 통해 제안한 DC-KQR의 효율적인 성능과 활용 가능성을 확인하였다.

• 대한기계학회논문집A
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• 제35권10호
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• pp.1205-1210
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• 2011

척추 불안정성은 요통과 관련되어 있다고 알려져 있다. 하지만 척추 불안정성과 관련된 임상적 연구가 충분하지 않아서 불안정성의 정의가 정량적으로 확립되어 있지 않다. 또한 추간판 퇴행 및 손상, 인대 결손, 협부 결손 등이 불안정성을 발생시키는 요인으로 알려져 있으나, 척추 불안정성에 미치는 영향이 명확하게 분석되어 있지 않다. 본 연구에서는 요추 단분절의 3 차원 유한요소 모델을 이용하여 인대 결손과 협부 결손이 단독 또는 복합적으로 척추 불안정성에 미치는 영향을 정량적으로 분석하였다. 여기서 굽힘 및 신전 시 척추의 시상각과 전위거리가 척추 불안정성을 나타내는 지표라고 가정하였다. 본 연구의 결과는 척추 불안정성의 원인과 기전을 이해하는데 도움이 될 수 있을 것이다.

• Smart Structures and Systems
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• 제26권4호
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• pp.403-418
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• 2020

In recent years, the use of Fiber Reinforced Polymers (FRPs) as one of the most common ways to increase the strength of concrete samples, has been introduced. Evaluation of the final strength of these specimens is performed with different experimental methods. In this research, due to the variety of models, the low accuracy and impact of different parameters, the use of new intelligence methods is considered. Therefore, using artificial intelligent-based models, a new solution for evaluating the bond strength of FRP is presented in this paper. 150 experimental samples were collected from previous studies, and then two new hybrid models of Imperialist Competitive Algorithm (ICA)-Artificial Neural Network (ANN) and Artificial Bee Colony (ABC)-ANN were developed. These models were evaluated using different performance indices and then, a comparison was made between the developed models. The results showed that the ICA-ANN model's ability to predict the bond strength of FRP is higher than the ABC-ANN model. Finally, to demonstrate the capabilities of this new model, a comparison was made between the five experimental models and the results were presented for all data. This comparison showed that the new model could offer better performance. It is concluded that the proposed hybrid models can be utilized in the field of this study as a suitable substitute for empirical models.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제29권4호
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• pp.699-722
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• 2015

본 연구의 목적은 라그랑주의 방정식론을 바탕으로 한 방정식의 해법을 고등학교 1학년 수업에 적용하여 방정식의 해법과 관련한 근과 계수의 관계와 대칭성의 의의를 인식하게 하는 것이다. 대칭성은 라그랑주의 방정식론의 핵심 아이디어이며, 근과 계수의 관계는 그의 해법에 있어 중요한 수단이다. 학생들은 수업을 통해 근과 계수의 관계에 대한 학습 의의를 인식하였고, 대칭성의 아이디어를 이해하였으며, 새로운 해법에 흥미를 나타내었다. 이러한 연구는 학교수학에서 다루는 국소적인 방정식의 해법만이 아닌 교수학적 조직화에 의한 체계적인 방정식론에 대한 경험을 주며, 방정식의 해법과 관련한 지식들의 연결성을 이해하게 한다.

• 한국가정과교육학회지
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• 제1권1호
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• pp.33-42
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• 1989

By the comparative analysis of high school Home Economics curricula in the U.S., Japan and Taiwan, this study first attempts to understand the current Home Economics education and to access its treads for each country. Based on the findings of the analysis, the study also seeks to get the major implications of the analysis for the betterment of the Korea Home Economics Education. The main sources of information and data analyzed here are： 1) curricula for both Oklahoma and Ohio state as representatives of the U.S.； 2) Home Economics Teaching Guidelines in Japan； and 3) Home Economics curriculum in Taiwan. Content Analysis technique is applied in this study. The major elements of contents include：1) structure of the curriculum； 2) subject name； 3) unit (time) allotment； 4) goals； 5) subject areas and content composition； and 6) other related characteristics for the implementation of the curriculum. Summarized results of the study outline as follows： 1) Home Economics is offered as independently required subject with equal status to Mathematics, Science, and Social Studies subject in all three countries； 2) Sex discrimination is prohibited both in the U.S. and Taiwan, while in Japan sex equity is not secured for Home Economics educations； 3) Time allotment for Home Economics in Japan and Taiwan is similiar to that in Korea；4) Subject areas cover such fields as Foods and Nutrition, Clothing and Textiles, Home Management, and Human Development in all three countries, which is similiar to those of Korea. In addition, Consumer Education and Career Education are also covered in the U.S., whereas in Japan Child Care is offered； and 5) Curriculum can be utilized as instructional planning material due to the clear specification of instructional methods, materials, and evaluation methods on the curriculum, especially in the U.S. and Taiwan.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제21권3호
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• pp.407-430
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• 2007

수학적 지식의 개인화/배경화, 탈개인화/탈배경화의 과정이 간과되거나 지나치게 강조됨으로써 발생하는 극단적 교수 현상은 항상 우리의 교수 실제에 내재하고 있으며, 사실 교사들을 심리적으로나 교수학적으로 압박하는 현상이라 볼 수 있다. 그러나 학생들이 수학 수업에서 보이는 오류나 오개념, 장애등에 관한 문제는 많은 연구가 이루어져 있지만 교사에 의해 나타나는 극단적 교수 현상에 대한 연구는 거의 이루어지지 않고 있다고 해도 과언은 아니다. 이에 본 연구에서는 네 가지 극단적 교수 현상에 대해 설명하고, 여러 가지 사례연구에서 다양한 예문들을 제시한 후 분석하는 방법으로 이들 극단적 교수 현상에 대한 이해를 도울 것이다. 또한 이러한 분석을 토대로 수학교실에서 나타나는 극단적 교수현상을 극복할 수 있는 방법에 대해서도 논의 할 것이다. 이 연구 논문은 교사들이 자기 자신의 수업을 반성하게 함으로써 극단적으로 진행되는 교수학적 현상의 기준이 될 것이고, 나아가 보다 나은 교수학적 상황을 고려하기 위한 자료를 제공할 것이다.