• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -1
• /
• pp.595-598
• /
• 2002

This paper proposes neighborhood reduction techniques in local search of the customer decomposition subproblem in the Multi Depots Vehicle Routing Problem with Time Windows (MDVRPTW) by using geospatial relation among depots and customers. The neighborhood of the customer decomposition subproblem can be simply and well defined but it should include excessively bad solution candidates. Our techniques find such candidates by using information of the problem domain, geographical relation. We use our techniques in Tabu Search and evaluate the effectiveness in computer experiment.

• 한국정밀공학회지
• /
• 제26권7호
• /
• pp.73-80
• /
• 2009

This paper describes a path planning algorithm, which is the minimal turning path based on the shape and size of the cell to clean up the whole area with two cleaning robots. Our method divides the whole cleaning area with each cell by cellular decomposition, and then provides some path plans among of the robots to reduce the rate of energy consumption and cleaning time of it. In addition we suggest how to plan between the robots especially when they are cleaning in the same cell. Finally simulation results demonstrate the effectiveness of the algorithm in an unknown area with multiple robots. And then we compare the performance index of two algorithms such as total of turn, total of time.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2010년도 하계학술대회
• /
• pp.9-11
• /
• 2010

Multiple-input multiple-output (MIMO) systems assisted by multi-relays with single antenna are considered. Signal transmission consists of two hops. In the first hop, the source node broadcasts the vector symbols to all relays, then all relays forward the received signals multiplied by each power gain to the destination simultaneously. Unlike the case of full cooperation between relays such as single relay with multiple antennas, in our case there is no closed form solution for optimal relay power gain with respect to minimum mean square error (MMSE). Thus we propose an alternative approach in which we use an approximation of the cost function based on rank-one matrix decomposition. As a cost function, we choose the trace of MSE matrix. We give several simulation results to validate that our proposed method obtains a negligible performance loss compared to optimal solution obtained by exhaustive search.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제50권3호
• /
• pp.121-129
• /
• 2001

In this paper, a new efficient feature extraction method based on Daubechies discrete wavelet transform is presented. This paper especially deals with the assessment of process statistical parameter using the features extracted from the wavelet coefficients of measured acoustic emission signals. Since the parameter assessment using all wavelet coefficients will often turn out leads to inefficient or inaccurate results, we selected that level-3 stage of multi decomposition in discrete wavelet transform. We make use of the feature extraction parameter namely, maximum value of acoustic emission signal, average value, dispersion, skewness, kurtosis, etc. The effectiveness of this new method has been verified on ability a diagnosis transformer go through feature extraction in stage of aging(the early period, the middle period, the last period)

• Geomechanics and Engineering
• /
• 제7권2호
• /
• pp.149-164
• /
• 2014

One of the most advanced classes of techniques for ground response analysis is based on the use of Transfer Functions. They represent the ratio of Fourier spectrum of amplitude motion at the free surface to the corresponding spectrum of the bedrock motion and they are applied in frequency domain usually by FFT method. However, Fourier spectrum only shows the dominant frequency in each time step and is unable to represent all frequency contents in every time step and this drawback leads to inaccurate results. In this research, this process is optimized by decomposing the input motion into different frequency sub-bands using Wavelet Multi-level Decomposition. Each component is then processed with transfer Function relating to the corresponding component frequency. Taking inverse FFT from all components, the ground motion can be recovered by summing up the results. The nonlinear behavior is approximated using an iterative procedure with nonlinear soil properties. The results of this procedure show better accuracy with respect to field observations than does the Conventional method. The proposed method can also be applied to other engineering disciplines with similar procedure.

• International Journal of Computer Science & Network Security
• /
• 제22권6호
• /
• pp.203-211
• /
• 2022

Multi-objective optimization problems (MOPs) arise in many real-world applications. MOPs involve two or more objectives with the aim to be optimized. With these problems improvement of one objective may led to deterioration of another. The primary goal of most multi-objective evolutionary algorithms (MOEA) is to generate a set of solutions for approximating the whole or part of the Pareto optimal front, which could provide decision makers a good insight to the problem. Over the last decades or so, several different and remarkable multi-objective evolutionary algorithms, have been developed with successful applications. However, MOEAs are still in their infancy. The objective of this research is to study how to use and apply machine learning (ML) to improve evolutionary multi-objective optimization (EMO). The EMO method is the multi-objective evolutionary algorithm based on decomposition (MOEA/D). The MOEA/D has become one of the most widely used algorithmic frameworks in the area of multi-objective evolutionary computation and won has won an international algorithm contest.

• 한국전산유체공학회지
• /
• 제20권2호
• /
• pp.7-15
• /
• 2015

This paper attempts to evaluate the accuracy and efficiency of a design optimization procedure by combining wavelets-based multi resolution analysis method and proper orthogonal decomposition (POD) technique. Aerodynamic design procedure calls for high fidelity computational fluid dynamic (CFD) simulations and the consideration of large number of flow conditions and design constraints. Thus, even with significant computing power advancement, current level of integrated design process requires substantial computing time and resources. POD reduces the degree of freedom of full system by conducting singular value decomposition for various field simulations. In this research, POD combined Design Optimization model is proposed and its efficiency and accuracy are to be evaluated. For additional efficiency improvement of the procedure, multi resolution analysis method is also being employed during snapshot constructions (POD training period). The proposed design procedure was applied to the optimization of wing aerodynamic performance. Throughout the research, it was confirmed that the POD/MRA design procedure could significantly reduce the total design turnaround time and also capture all detailed complex flow features as in full order analysis.

• 한국컴퓨터그래픽스학회논문지
• /
• 제25권3호
• /
• pp.21-29
• /
• 2019

본 논문에서는 구조-텍스처 분할 기법을 기반으로 위성영상을 분할 융합하여 공간 해상도를 개선시키는 프레임워크를 제시한다. 위성영상은 센서가 감지하는 파장에 따라 다양한 공간해상도를 가진다. 전정 영상 (panchromatic image)은 일반적으로 높은 공간해상도를 가지지만 단일 흑백컬러를 가지고 있는 반면, 다중분광 영상 (multi-spectral image)나 적외선 영상은 전정 영상에 비해 낮은 공간해상도를 가지지만 다양한 분광 밴드정보와 열 정보를 가지고 있다. 본 논문에서는 다중분광 영상이나 적외선 영상의 공간 해상도를 향상시키기 위해 영상의 디테일이 텍스처 영상에만 존재한다는 것에 착안하여 본 프레임워크를 고안하였다. 고안된 프레임워크에서는 저해상도 영상과 고해상도 영상이 구조 영상과 텍스처 영상으로 분할된 뒤, 저해상도 구조영상은 고해상도 구조 영상을 참조하여 가이디드 필터링 된다. 구조-텍스처 영상 모델에 따라 필터링된 저해상도 영상의 구조 영역과 고해상도 영상의 텍스처 영역을 픽셀 단위로 더해져서 최종 영상이 생성된다. 생성된 영상은 저해상도 영상의 밴드와 고해상도 영상의 디테일을 포함한다. 제시하는 방법은 분광해상도와 공간해상도를 모두 보존할 수 있음을 실험적으로 확인하였다.

• 한국정보통신학회논문지
• /
• 제26권6호
• /
• pp.842-849
• /
• 2022

딥러닝 기술의 발달로 무인 자동차, 드론, 로봇 등의 임베디드 시스템 분야에서 DNN을 활용하는 사례가 많아지고 있다. 대표적으로 자율주행 시스템의 경우 정확도가 높고 연산량이 큰 몇 개의 DNN들을 동시에 수행하는 것이 필수적이다. 하지만 상대적으로 낮은 성능을 갖는 임베디드 환경에서 다수의 DNN을 동시에 수행하면 추론에 걸리는 시간이 길어진다. 이러한 현상은 추론 결과에 따른 동작이 제때 이루어지지 않아 비정상적인 기능을 수행하는 문제를 발생시킬 수 있다. 이를 해결하기 위하여 본 논문에서 제안한 솔루션은 먼저 연산량이 큰 DNN에 터커 분해 기법을 적용하여 연산량을 감소시킨다. 그다음으로 DNN 모델들을 GPU 내부에서 은닉층 단위로 최대한 병렬적으로 수행될 수 있게 한다. 실험 결과 DNN의 추론 시간이 제안된 기법을 적용하기 전 대비 최대 75.6% 감소하였다.

• 경제분석
• /
• 제26권4호
• /
• pp.65-97
• /
• 2020

본 논문의 목적은 우리나라 수출의 고용파급효과와 그 변화 요인을 상세히 분석하는 데 있다. 이를 위해 가장 최근에 공표된 World Input-Output Database (WIOD)의 2000년부터 2014년까지의 세계산업연관표와 사회경제계정을 이용하여 다지역산업연관 및 구조적 요인 분해 분석을 실시하였다. 주요 분석 결과는 다음과 같다. 첫째, 우리나라 수출에 체화된 고용은 지속적으로 증가하였고, 우리나라 고용의 수출 의존도 역시 상승 추세를 보였다. 그러나 부가가치 수출의 고용유발계수는 전반적으로 하락하는 것으로 나타났다. 둘째, 우리나라 수출에 체화된 고용의 상당 부분은 중국, 미국, RoW(Rest of the World)의 최종수요에 기인한 것으로 분석되었다. 셋째, 우리나라 수출에 체화된 고용의 증대에 가장 큰 영향을 준 요인은 해외 최종수요의 변화 요인이었다. 이러한 실증분석 결과에 기초하여 우리나라의 국내 고용 확대를 위한 의미 있는 정책적 시사점을 논의하였다.