• Title/Summary/Keyword: Design of experiments

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Experimental Investigations of Accuracy Improvement in Wind Tunnel Testing Using Design of Experiments (실험설계법 기반 풍동실험 정밀도 향상 실험연구)

  • Oh, Se-Yoon;Park, Seung-O;Ahn, Seung-Ki
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.4
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    • pp.291-297
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    • 2014
  • A Design of Experiments(DOE) approach to an experimental study of fuselage drag and stability characteristics of a helicopter configuration was applied to achieve an accuracy improvement in the wind tunnel testing. The impact of blocking the test was assessed by comparing the ANOVA table for the blocked and unblocked cases. For a second-order response model, the role of blocking resulted in a substantial increase in the accuracy of test results. These accuracy improvement could be achieved through randomization, blocking, and replication of the data points i.e. a re-ordering of the test sequence where the data were acquired.

Correlation Analysis of Parameters affecting Pressure Distributions in Vertical Shafts by Design of Experiments (실험계획법에 의한 수직샤프트내 압력분포에 영향을 미치는 인자간 상관관계 분석)

  • Han, Hwa-Taik;Shin, Chul-Yong
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.883-888
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    • 2008
  • Various effluents generated in cooking processes contribute a great deal to indoor air pollution among many other indoor pollutants such as dusts from outdoor and carbon dioxide from human body. Kitchen exhaust hoods are not believed to exhaust indoor contaminants properly in many cases, while generating too much noise. Instead of focusing on individual products of kitchen hoods, we should address the problem by attacking the ventilation system as a whole including vertical shafts and building air-tightness. In this study, it is intended to investigate the pressure distribution along the vertical shaft depending on various system parameters, such as shaft size, concurrent hood usage rate, roof fan, inlet pressure loss, and outdoor temperature. The maximum static pressure in the vertical shaft has been obtained using the method of design of experiments and analyzed by the analysis of variance. The results can be used for the design of kitchen exhaust systems by analyzing the pressure distributions in vertical shafts.

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Methodology of Ni-base Superalloy Development for VHTR using Design of Experiments and Thermodynamic Calculation (실험 계획법 및 열역학 계산법을 이용한 초고온가스로용 니켈계 초합금 설계 방법론)

  • Kim, Sung-Woo;Kim, Dong-Jin
    • Corrosion Science and Technology
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    • v.12 no.3
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    • pp.132-141
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    • 2013
  • This work is concerning a methodology of Ni-base superalloy development for a very high temperature gas-cooled reactor(VHTR) using design of experiments(DOE) and thermodynamic calculations. Total 32 sets of the Ni-base superalloys with various chemical compositions were formulated based on a fractional factorial design of DOE, and the thermodynamic stability of topologically close-packed(TCP) phases of those alloys was calculated by using the THERMO-CALC software. From the statistical evaluation of the effect of the chemical composition on the formation of TCP phase up to a temperature of 950 oC, which should be suppressed for prolonged service life when it used as the structural components of VHTR, 16 sets were selected for further calculation of the mechanical properties. Considering the yield and ultimate tensile strengths of the selected alloys estimated by using the JMATPRO software, the optimized chemical composition of the alloys for VHTR application, especially intermediate heat exchanger, was proposed for a succeeding experimental study.

Characterization of Microscale Drilling Process for Functionally Graded M2-Cu Material Using Design of Experiments (실험계획법을 이용한 M2-Cu 기능성 경사 재료의 마이크로 드릴링 특성 평가)

  • Sim, Jongwoo;Choi, Dae Cheol;Shin, Ki-Hoon;Kim, Hong Seok
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.5
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    • pp.502-507
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    • 2015
  • In this study, a microscale drilling process was conducted to evaluate the cutting characteristics of functionally graded materials. A mixture of M2 and Cu powders were formed and sintered to produce disk specimens of various compositions. Subsequently, a microscale hole was created in the specimen by using a desktop-size micro-machining system. By using design of experiments and analysis of variance, it was found that the M2-Cu composition, spindle speed, and the interactions between these two factors had significant effects on the magnitude of cutting forces. However, the influence of feed rate on the cutting force was negligible. A mathematical model was established to predict the cutting force under a wide range of process conditions, and the reliability of the model was confirmed experimentally. In addition, it was observed that increasing the wt% of Cu in an M2-Cu specimen increased the high-frequency amplitude of cutting forces.

A Study on the Optimum Design of the Automotive Side Member to Maximize the Crash Energy Absorption Efficiency (충돌에너지 흡수효율 최대화를 위한 자동차 사이드 멤버 최적 설계에 관한 연구)

  • Lee, Jung Hwan;Jeong, Nak Tak;Suh, Myung Won
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.11
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    • pp.1179-1185
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    • 2013
  • In this study, the design optimization of the automotive side member is performed to maximize the crash energy absorption efficiency per unit weight. Design parameters which seriously influence on the frontal crash performance are selected through the sensitivity analysis using the Plackett-Burman design method. And also the design variables, which are determined from the sensitivity analysis, are optimized by two methods. One is conventional approximate optimization method which uses the statistical design of experiments (DOE) and response surface method (RSM). The other is a methodology derived from previous work by the authors, which is called sequential design of experiments (SDOE), to reduce a trial and error procedure and to find an appropriate condition for using micro-genetic algorithm. The proposed optimization technique shows that the automotive side member structure can be designed considering the frontal crash performance.

Process Optimization for Thermal-sprayed Ni-based Hard Coating by Design of Experiments (실험계획법에 의한 니켈기 경질 용사코팅의 최적 공정 설계)

  • Kim, K.T.;Kim, Y.S.
    • Journal of Power System Engineering
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    • v.13 no.5
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    • pp.89-94
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    • 2009
  • In this work, the optimal process has been designed by $L_9(3^4)$ orthogonal array and analysis of variance(ANOVA) for thermal-sprayed Ni-based hard coating. Ni-based hard coatings were fabricated by flame spray process on steel substrate. Then, the hardness test and observation of microstructure of the coatings were performed. The results of hardness test were analyzed by ANOVA. The ANOVA results demonstrated that the acetylene gas flow had the greatest effect on hardness of the coatings. The oxygen gas flow was found to have a neglecting effect. From these results, the optimal combination of the flame spray parameters could be predicted. The calculated hardness of the coatings by ANOVA was found to lie close to that of confirmation experimental result. Thus, it was considered that design of experiments design using orthogonal array and ANOVA was useful to determine optimal process of thermal-sprayed Ni-based hard coating.

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Optimal Design of A Quick-Acting Hydraulic Fuse Using Design of Experiments and Complex Method (실험계획법과 콤플렉스법에 의한 고성능 유압휴즈의 최적 설계)

  • Lee, Seong Rae
    • Journal of Drive and Control
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    • v.12 no.4
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    • pp.8-14
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    • 2015
  • A quick-acting hydraulic fuse, which is mainly composed of a poppet, a seat, and a spring, must be designed to minimize the leaked oil volume during fuse operation on a line rupture. The optimal design parameters of a quick-acting hydraulic fuse were searched using the design of experiments method and the complex method. First, the $L_{50}(5^4)$ orthogonal array is used to find the robust minimum point among the 625 points of design variables. The search range can then be narrowed around the robust minimum point. Second, the $L_{25}(5^4)$ orthogonal array is used to obtain the variations of the design variables in the narrowed search range. The variations of design variables are used to set the structure of a polynomial equation representing the leakage oil volume of the quick-acting hydraulic fuse. The least squares method is then applied to obtain the coefficients of polynomial equation. Finally, the complex method is used to find the optimal design parameters where the objective function is described by the polynomial equation.

Experimental Investigations of Systematic Errors in Wind Tunnel Testing Using Design of Experiments (실험설계법 기반 풍동시험 시스템 오차 검출 실험연구)

  • Oh, Se-Yoon;Park, Seung-O;Ahn, Seung-Ki
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.5
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    • pp.335-341
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    • 2013
  • The variation of systematic bias errors in the wind tunnel testing has been studied. A Design of Experiments(DOE) approach to an experimental study of fuselage drag and stability characteristics of a helicopter configuration was applied. When forces and moments measured in one time block differ significantly from measurements made in another time block under assumption that sample observations can be expected to yield same results within permissible measuring errors. The practical implication of this paper is that the systematic error can not be assumed not to exist. The those error reduction could be achieved through the process of randomization, blocking, and replication of the data points.

A Study on Spindle Shape Design using Design of Experiments (실험계획법을 이용한 주축 형상 설계에 관한 연구)

  • Shin, Jae-Ho;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.4
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    • pp.120-127
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    • 2009
  • Spindle units of machine tool are very important part in the manufacturing area. Recently high speed machining has become the main issue of metal cutting. To develop high speed machine tools, a lot of studies have been carried out for high speed spindle. Due to increase of the rotational speed of the spindle, there has been renewal of interest in vibration of spindle. This paper concerns the improvement of spindle design using design of experiments. To improve the design of critical speed and weight of spindle, the experiments using central composite method have been carried out. The targets are critical speed and weight of spindle. For optimization of critical speed and weight and optimization of only critical speed by operation of all area search through response optimizer, the result of analysis has improved design of each factor. Finite element analyses are performed by using the commercial codes ARMD, CATIA V5 and ANSYS workbench. From the results, it has been shown that the proposed method is effective for modification of spindle design to improve critical speed and weight.

Microstructure Characterization of TiO2 Photoelectrodes for dyesensitized Solar Cell using Statistical Design of Experiments

  • Lee, Sung-Joon;Cho, Il-Hwan;Kim, Hyun-Wook;Hong, Sang-Jeen;Lee, Hun-Yong
    • Transactions on Electrical and Electronic Materials
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    • v.10 no.5
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    • pp.177-181
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    • 2009
  • Employing statistical design of experiments, we have performed studies on the characterization of electrodes using $TiO_2$ and process variables in the fabrication process of nanocrystalline dye sensitized solar cell. Systematic experiment to identify the effects of process variables on cell's efficiency has based on broad-band absorption of light by tailor made organometallic dye molecules dispersed on a high surface of $TiO_2$. Employing statistical design of experiment on $TiO_2$ photoelectrode forming process, structural characterization of electrodes and process variable have been investigated. Through the statistical analysis we have found that the particle size of $TiO_2$ and the amount of PEG/PEO are significantly affecting on the cell efficiency. In addition, a significant amount of interaction exists between the particle size and the amount of PEG/PEO.