• 한국정밀공학회지
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• 제27권12호
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• pp.92-98
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• 2010

The design of press bonding tool in LCD module equipment is a very complex and difficult task because many design able variables are involved while their effects are not known. It takes longtime experiments and much expenses to verify the effects of these design variables. However the optimization of bonding tool using OLB(outer lead bonding) and PCB Bonding is a very important problem in LCD manufacturing process, so much design efforts have been made for improving the bonding tool performance. In this paper, a reasonable and fast process which gives optimized solution under the design requirements has been presented. Both analytical and statistical methods are employed in this process. A reliable analytic model using experiment-oriented FE analysis can be obtained, in which the regression equations that predict the tool efficiency from various DOE method are found. Improvement of tool efficiency could be estimated by the regression equations using meaningful factors converged by RSM(Response Surface Method). With this process a reasonable optimized solution that meets a variety of design requirements can be easily obtained.

• 한국세라믹학회지
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• 제43권9호
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• pp.519-526
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• 2006

A full-factorial design of experiments with three input factors and two levels for each factor including center points was utilized for the preparation and characterization of twelve types of $BaTiO_3$ slips for tape casting. Ceramic powders with different particle sizes, different milling methods such as high energy milling and conventional ball milling, and two types of dispersant with different polymeric species were chosen as input factors in order to investigate their effects on slip and on green tape properties. Tape casting, a small rectangular-shaped K-square preparation, characterization and quantitative data analysis using statistical software were followed. Ceramic powder was the most significant among three input factors for the output responses of slip viscosity and green tape density, showing more favorable results with large particles than with very fine ones. In addition, high energy milling for only 30 min was more efficient than 24h of conventional ball milling in terms of powder dispersion and milling. The optimum condition based on the experimental results was a slip exposed to high energy milling with large ceramic particles along with a methylethyl acetate dispersant.

• 한국지반공학회논문집
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• 제16권1호
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• pp.227-234
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• 2000

Soilcrete는 도로포장과 연약지반개량공사에 널리 활용되고 있는 전통적인 재료이지만 내구성이 떨어지고 품질이 불균질하기 때문에 용도확대에 제약을 받아왔다. 그러나 최근 환경친화적인 수요가 증가하면서 공원의 산책로, 골프장의 보도 등에 고강도 소일크리트의 적용사례가 증가하고 있다 본 연구의 목적은 포졸란 시멘트를 이용한 고강도 소일크리트에 대해서 통계적인 실험계획법을 적용하여 참고 배합설계를 실시하고자 하였다. 시험토질은 국내 현장에서 흔히 볼 수 있는 점토를 대상으로 하였으며, 연구결과 압축강도$50~150kg/cm^2$수준의 고강도 소일크리트에 대한 실용적인 참고 배합표를 제안할 수 있었다.

• Structural Engineering and Mechanics
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• 제73권5호
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• pp.501-513
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• 2020

In the present work, the optimization of machining parameters to achieve the desired technological parameters such as surface roughness, tool radial vibration and material removal rate have been carried out using response surface methodology (RSM). The hard turning of EN19 alloy steel with coated carbide (GC3015) cutting tools was studied. The main problem faced in manufacturer of hard and high precision components is the selection of optimum combination of cutting parameters for achieving required quality of surface finish with maximum production rate. This problem can be solved by development of mathematical model and execution of experiments by RSM. A face centred central composite design (FCCD), which comes under the RSM approach, with cutting parameters (cutting speed, feed rate and depth of cut) was used for statistical analysis. A second-order regression model were developed to correlate the cutting parameters with surface roughness, tool vibration and material removal rate. Consequently, numerical and graphical optimization were performed to obtain the most appropriate cutting parameters to produce the lowest surface roughness with minimal tool vibration and maximum material removal rate using desirability function approach. Finally, confirmation experiments were performed to verify the pertinence of the developed mathematical models.

• Communications for Statistical Applications and Methods
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• 제29권2호
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• pp.177-191
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• 2022

This paper addresses the use of machine learning methods for causal estimation of treatment effects from observational data. Even though conducting randomized experimental trials is a gold standard to reveal potential causal relationships, observational study is another rich source for investigation of exposure effects, for example, in the research of comparative effectiveness and safety of treatments, where the causal effect can be identified if covariates contain all confounding variables. In this context, statistical regression models for the expected outcome and the probability of treatment are often imposed, which can be combined in a clever way to yield more efficient and robust causal estimators. Recently, targeted maximum likelihood estimation and causal random forest is proposed and extensively studied for the use of data-adaptive regression in estimation of causal inference parameters. Machine learning methods are a natural choice in these settings to improve the quality of the final estimate of the treatment effect. We explore how we can adapt the design and training of several machine learning algorithms for causal inference and study their finite-sample performance through simulation experiments under various scenarios. Application to the percutaneous coronary intervention (PCI) data shows that these adaptations can improve simple linear regression-based methods.

• Computers and Concrete
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• 제21권5호
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• pp.485-493
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• 2018

Statistical analysis has found useful application in the design of experiments (DOE) especially optimization of concrete ingredients however, to be able to apply the concept properly using computer aided applications there has to be an upper and lower limits of responses fed to the system. In this study, the production of high-performance steel fiber concrete (HPSFC) at five different fiber addition levels by volume with two aspect ratios of 60 and 83 were studied under two curing methods completely dry cured (DC) and moist cured (MC) conditions. In other words, this study was carried out for those limits based on material properties available in North Cyprus. Specimens utilized were cubes 100 mm size casted and cured for 28 days and tested for compressive strength. Minitab 18 statistical software was utilized for the analysis of results at a 5 per cent level of significance. Experimentally, it was observed that, there was fluctuation in compressive strength results for the two aspect ratios and curing regimes. On the other hand P-value hypothesis evaluation of the response showed that at the stated level of significance, there was a statistically significant difference between dry and moist curing conditions. Upper and lower limit values were proposed for the response to be utilized in DOE for future studies based on these material properties. It was also suggested that for a narrow confidence interval and accuracy of the system, future study should increase the sample size.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.274-278
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• 2003

통계실험계획법 중 하나인 Plackette-Burman법을 사용하여 실험을 설계하였으며, 수행된 실험을 통하여 6가지 인자 중 main effect의 절대값이 높은 당, nitrogen, 온도를 최종 선정할 수 있었으며, main effect 값이 양의 값을 가지는 당과 nitrogen은 첨가 농도가 높을수록, 음의 값을 가지는 온도는 낮을수록 실험에 유리하다는 것을 확인할 수 있었다.

• 대한산업공학회지
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• 제33권4호
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• pp.393-401
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• 2007

Affective aspects of design attributes such as color, Pattern, and texture are important to the overall impression and the success of interior products. Among all the interior materials, wallpapers and flooring materials take up largest construction area and they are main components in creating affective impression for customers. This study aims to investigate the relationship between luxuriousness and related affective variables and design elements of wallpapers and flooring materials. The approach consists of 3 steps: (1) selecting related affective features and product design attributes through a literature survey, opinion of expert panel, and focus group interview, (2) conducting evaluation experiments, and (3) developing Kansei models using multivariate statistical analysis and analyzing critical attributes. Evaluation experiment was conducted using a questionnaire made up of 7-point scale and 100-point scale and 30 housewives and 20 interior designers participated in the evaluation experiment. The result of evaluation was analyzed through principal component regression and quantification I analysis. As a result of analyzing the survey data, the relationship between luxuriousness and related affective features and product design attributes was identified, moreover a optimal combination of the design component was identified. Consequently, it is expected that the results of the study would be a basis of the concept of emotion-based design by giving insights about how customers perceive the luxuriousness and suggesting the optimal combination, and providing specific quantitative design guidelines.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2150-2158
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• 2002

A recent research and development has the requirement for the optimization to shorten design time of modified or new product model and to obtain more precise engineering solution. General optimization problem must consider many conflicted objective functions simultaneously. Multi-objective optimization treats the multiple objective functions and constraints with design change. But, real engineering problem doesn't describe accurate constraint and objective function owing to the limit of representation. Therefore this study applies variance analysis on the basis of structure analysis and DOE to the vertical roller mill fur portland cement and proposed statistical design model to evaluate the effect of structural modification with design change by performing practical multi-objective optimization considering mass, stress and deflection.

• 대한인간공학회지
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• 제28권4호
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• pp.61-69
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• 2009

With increasing needs for affective design, it became an essential part in a product development process to look up quantitative ergonomic data that reflects customers' preferences on design factors in various products. This study looked at wide LCD monitors and analyzed customers' affective preferences regarding monitor's bezel frame size and shape. The monitor's bezel frame depth, size and ratio were selected as independent variables among many design parameters. As dependent variables, customer's subjective preferences were measured. A statistical analysis revealed that monitor's bezel frame depth, size and ratio had significant effects on customer's preferences. Also, it was possible to find a different tendency on affective variables and their levels for 19" and 24" wide LCD monitors. In general, experiments revealed that customers reacted more sensitively in 24" wide LCD monitors to all variables. In 19" wide LCD monitors, only the lower frame bezel size had a significant effect, otherwise, lower, upper and side frame bezels appeared to be effective variables in 24" monitors. In order to reflect customer's affective preferences to new design of wide LCD monitors, this study is expected to provide quantitative ergonomic data and guidelines for the design of wide LCD monitor's bezel frame depth and size.