• 제어로봇시스템학회논문지
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• 제22권1호
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• pp.53-58
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• 2016

Various jumping robot platforms have been developed to carry out missions such as rescues, explorations, or inspections of dangerous environments. We suggested a jumping robot platform using energy conversion of the elastic body like the bar of a pole vault, which is the main part in which elastic force occurs. The compliant link was optimized by an optimization method based on Taguchi methodology, and the robot's leaping ability was improved. Among the parameters, the length, width, and thickness of the link were selected as design variables first while the others were fixed. The level of the design variables was settled, and an orthogonal array about its combination was made. In the experiment, dynamic simulations were conducted using the DAFUL program, and response table and sensitivity analyses were performed. We found optimized values through a level average analysis and sensitivity analysis. As a result, the maximum leaping height of the optimized robot increased by more than 6.2% compared to the initial one, and these data will be used to design a new robot.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5860-5876
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• 2018

A single snapshot data can only provide limited amount of information so that the rank of covariance matrix is not full, which is not adopted to complete the parameter estimation directly using the traditional super-resolution method. Aiming at solving the problem, a joint time delay and angle estimation using matrix pencil method based on information reconstruction vector for orthogonal frequency division multiplexing (OFDM) signal is proposed. Firstly, according to the channel frequency response vector of each array element, the algorithm reconstructs the vector data with delay and angle parameter information from both frequency and space dimensions. Then the enhanced data matrix for the extended array element is constructed, and the parameter vector of time delay and angle is estimated by the two-dimensional matrix pencil (2D MP) algorithm. Finally, the joint estimation of two-dimensional parameters is accomplished by the parameter pairing. The algorithm does not need a pseudo-spectral peak search, and the location of the target can be determined only by a single receiver, which can reduce the overhead of the positioning system. The theoretical analysis and simulation results show that the estimation accuracy of the proposed method in a single snapshot and low signal-to-noise ratio environment is much higher than that of Root Multiple Signal Classification algorithm (Root-MUSIC), and this method also achieves the higher estimation performance and efficiency with lower complexity cost compared to the one-dimensional matrix pencil algorithm.

• 한국자동차공학회논문집
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• 제13권2호
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• pp.72-82
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• 2005

The objective of this paper is to describe the optimization of design parameters in a large-sized commercial bus heater system by using CFD(computational fluid dynamics) analysis and Taguchi method. In order to obtain the best combination of each control factor which results in a desired performance of heater system, the parameter design of the Taguchi method is adopted for the robust design considering the dynamic characteristic. The research activity may be divided into four phases. The first one is analyzing the problem, i.e., ascertaining the influential factors. In the second phase the levels were set in such a way that their variation would significantly influence the response. In the third phase the experimental runs were designed. In the final phase the planned runs were carried out numerically to evaluate the optimal combination of factors which is able to provide the best response. In this study, eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the $L_{18}(2^1{\times}3^7)$ orthogonal array. The results of this study can be summarized as follows ; (i)The optimum condition of control factor is a set of <$A_2\;B_1\;C_3\;D_3\;E_1\;F_2\;G_3\;H_2$> where A is shape of the outer fin, B is pitch of the outer fin, C is height of the outer fin, D is the inner fin number, E is the inner fin height, F is length of the flame guide, G is diameter of the heating element and H is clearance between air guide and heating element. (ii)The heat capacity of heated discharge air under the optimum condition satisfies the equation y=0.6M w here M is a signal factor. (iii)The warm-up rate improves about three times, more largely as com pared with the current condition, which results in about 9.2minutes reduction.

• 한국지능시스템학회논문지
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• 제19권1호
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• pp.145-151
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• 2009

유비쿼터스 네트워크의 실현을 위한 4세대 통신방식의 유력한 후보로 부상하는 OFDM (Orthogonal Frequency Division Multiplexing) 통신방식이 육상에서 주목받고 있으며, 고속 데이터 전송을 위한 Wireless LAN의 표준기술로 확정되어 있다. 해상통신의 경우에서도 OFDM 통신방식은 VHF 대역을 이용한 데이터 전송방식으로 제안되고 있으며 ITU (International Telecommunication Union)는 해상통신에서 32-point FFT (Fast Fourier Transform)를 사용하도록 권고하고 있다. 해상 통신에서는 해양사고 및 조난 시에도 통신이 이루어져야 하는 한계상황을 고려하면 OFDM 통신시스템의 중요 디바이스인 FFT는 저전력으로 동작되어야 한다. 따라서 본 논문에서는 OFDM 방식의 중요 디바이스인 32-point FFT를 저전력으로 동작시키기 위해 radix-2와 radix-4를 이용하여 저전력 32-point FFT 알고리즘을 제안한다. 최적화된 설계로 32-point FFT를 저전력 동작이 가능하도록 설계하였으며, 제안한 알고리즘은 VHDL (VHSIC hardware description language)로 구현하고 FPGA (field-programmable gate array) Spartan3 board에 장착하여 Matlab의 이론값과 비교, 검증하였다.

• 한국정밀공학회지
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• 제20권3호
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• pp.50-57
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• 2003

In this study, the structural optimal design was applied to the girder of over head crane. The optimization was carried out using ANSYS code fur the deadweight of girder, especially focused on the thickness of its upper, lower, reinforced and side plates. The weight could be reduced up to around 15% with constraints of its deformation, stress and buckling strength. The structural safety was also verified by the buckling analysis of its panel structure. It might be thought to be very useful to design the conventional structures fur the weight save through the structural optimization. The objective function and restricted function were estimated by the orthogonal array, and the sensitivity analysis of design variable fur that was operated.

• 대한기계학회논문집
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• 제16권3호
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• pp.514-526
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• 1992

본 연구에서는 Taguchi 방법에 사용된 직교배열 이용 실험 계획법에 의한 최 적화 방법으로 보강된 복합재 쉘 구조의 좌굴강도 최적화를 수행하고 타당성을 고찰하 였다.한 방향의 압축하중을 받는 단순 지지된 복합재 평판과 Cut-out을 가진 원통 형 판넬의 보강재 및 섬유방향 최적 설계에 본 방법을 적용시켜 본 결과, 현저한 설계 개선과 아울러 각 설계 변수가 좌굴강도에 미치는 영향을 파악할 수 있었다. 특히 이 방법은 함수의 미분값을 이용한 민감도 해석대신에 함수값의 평균치 분석(ANOM)및 분산 분석(ANOVA)을 사용하기 때문에 설계변수의 변화에 덜 민감한 설계를 얻을 수 있 다.

• 동력기계공학회지
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• 제17권6호
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• pp.95-101
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• 2013

A stereo PIV measurements in a circulating water channel has been performed to investigate the skin friction reduction mechanism of the outer-layer vertical blades first devised by Hutchins. In a recent PIV measurement study, considerable skin friction reduction was achieved as much as 2.73%~7.95% by outer-layer vertical blades array. In the present study, the influence of vertical blades array upon the characteristics of the turbulent coherent structures was analyzed by proper orthogonal decomposition method. It is observed that the vortical structures are cut and deformed by blades array and also the turbulent intensity and the Reynolds stress were weakened by the blades. These phenomena strongly associate the skin-friction drag reduction mechanism in the turbulent boundary layer flow.

• 산업경영시스템학회지
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• 제20권41호
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• pp.25-31
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• 1997

A study to analyze and solve problems of a biochemical process experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 춘계학술대회
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• pp.265-273
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• 2000

A study to analyze and solve problems of polyacetal resin cutting experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/H ratio.

• 대한안전경영과학회지
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• 제5권1호
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• pp.103-113
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• 2003

A study to analyze and solve problems of a stone surface process experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.