• Journal of Korean Society for Quality Management
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• v.39 no.3
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• pp.400-411
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• 2011

Process variables are factors in an experiment that are not mixture components but could affect the blending properties of the mixture ingredients. For example, the effectiveness of an etching solution which is measured as an etch rate is not only a function of the proportions of the three acids that are combined to form the mixture, but also depends on the temperature of the solution and the agitation rate. Efficient designs for the mixture components-process variables experiments depend on the mixture components-process variables model which is called a combined model. We often use the product model between the canonical polynomial model for the mixture and process variables model as a combined model. In this paper we propose three starting models for the mixture components-process variables experiments. One of the starting model we are considering is the model which includes product terms up to cubic order interactions between mixture effects and the linear & pure quadratic effect of the process variables from the product model. In this paper, we propose a method for finding robust designs and practical designs with respect to D-, G-, and I-optimality for the various starting combined models and then, we find practically efficient and robust designs for estimating the regression coefficients for those models. We find the prediction capability of those recommended designs in the case of three components and three process variables to be good by checking FDS(Fraction of Design Space) plots.

• Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.268-281
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• 2023

Coral reef fisheries are prominent for the archipelagic countries' food sufficiency and security. Studies showed that fish abundance and biomass are affected by biophysical variables. The present study determines which biophysical variables are important predictors of fish diversity, abundance, and biomass. The study used available monitoring data from the Indonesian Research Center for Oceanography, the National Board for Research and Innovation. Data were collected from 245 transects in 19 locations distributed across the Indonesian Archipelago, including the eastern Indian Ocean, Sunda Shelf (Karimata Sea), Wallacea (Flores and Banda Seas), and the western Pacific Ocean. Principal component analysis and multiple regression model were administered to 13 biophysical metrics against 11 variables of coral reef fishes, i.e., diversity, abundance, and biomass of coral reef fishes at three trophic levels. The results showed for the first time that the covers of other fauna, coral rubbles, and soft corals were the three most important predictor variables for nearly all coral reef fish variables. Other fauna cover was the important predictor for all 11 coral reef fish variables. Coral rubble cover was the predictor for ten variables, but carnivore fish abundance. Soft coral cover was a good predictor for corallivore, carnivore, and targeted fishes. Despite important predictors for corallivore and carnivore fish variables, hard coral cover was not the critical predictor for herbivore fish variables. The other important predictor variables with a consistent pattern were dead coral covered with algae and rocks. Dead coral covered with algae was an important predictor for herbivore fishes, while the rock was good for only carnivore fishes.

• Journal of Engineering Education Research
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• v.16 no.3
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• pp.10-19
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• 2013

Recently, Korean universities have increased the number of English Medium Instruction (EMI) lectures in order to allow students to gain both specialized knowledge and enhanced English ability. Previous researches on effective EMI lectures have focused on exploring the effects of learners' cognitive and affective characteristics on learning outcomes. Whereas the input variables of learning have been investigated as predicting variables of effects in EMI lectures, there has been a few research for investigating process variables to yield learning outcomes. The purpose of this study is to analyze the structural relationships among variables affecting on learner satisfaction and effects. The participants are 209 engineering students from various majors. Independent variables are defined as English motivation, English competency, and English confidence, a mediated variable is Cognitive engagement, and dependent variables are Learning satisfaction and Educational effect perception. The results show that the relationships are statistically significant: learners' English competency & English confidence ${\rightarrow}$ Cognitive engagement ${\rightarrow}$ Learning satisfaction ${\rightarrow}$ Educational effect perception. Especially, the structural model confirms that the effect of learners' English confidence on Learning satisfaction and Educational effect perception is mediated by the level of learners' Cognitive engagement. Further, the implication for effective EMI lectures is discussed based on the observed research results.

• Journal of the Ergonomics Society of Korea
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• v.19 no.2
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• pp.87-99
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• 2000

This study aims to examine a fuzzy logic-based human expert EMG prediction model (FLHEPM) for predicting electromyographic responses of trunk muscles due to manual lifting based on two task (control) variables. The FLHEPM utilizes two variables as inputs and ten muscle activities as outputs. As the results, the lifting task variables could be represented with the fuzzy membership functions. This provides flexibility to combine different scales of model variables in order to design the EMG prediction system. In model development, it was possible to generate the initial fuzzy rules using the neural network, but not all the rules were appropriate (87% correct ratio). With regard to the model precision, the EMG signals could be predicted with reasonable accuracy that the model shows mean absolute error of 8.43% ranging from 4.97% to 13.16% and mean absolute difference of 6.4% ranging from 2.88% to 11.59%. However, the model prediction accuracy is limited by use of only two task variables which were available for this study (out of five proposed task variables). Ultimately, the neuro-fuzzy approach utilizing all five variables to predict either the EMG activities or the spinal loading due to dynamic lifting tasks should be developed.

• Computers and Concrete
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• v.14 no.4
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• pp.445-462
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• 2014

To solve structural optimization problems, it is necessary to integrate a structural analysis package and an optimization package. There have been many packages that can be employed to analyze reinforced concrete plane frames. However, because most structural analysis packages suffer from closeness of systems, it is very difficult to integrate them with optimization packages. To overcome the difficulty, we proposed a possible alternative, DAMDO, which integrates Design, Analysis, Modeling, Definition, and Optimization phases into an integration environment as follows. (1) Design: first generate many possible structural design alternatives. Each design alternative consists of many design variables X. (2) Analysis: employ the structural analysis software to analyze all structural design alternatives to obtain their internal forces and displacements. They are the response variables Y. (3) Modeling: employ artificial neural networks to build the models Y=f(X) to obtain the relationship functions between the design variables X and the response variables Y. (4) Definition: employ the design variables X and the response variables Y to define the objective function and constraint functions. (5) Optimization: employ the optimization software to solve the optimization problem consisting of the objective function and the constraint functions to produce the optimum design variables. The RC frame optimization problem was examined to evaluate the DAMDO approach, and the empirical results showed that it can be solved by the approach.

• The Korean Journal of Community Living Science
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• v.18 no.1
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• pp.63-70
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• 2007

The purpose of this study is to find out how family, school and community variables influence internet behavior problems in adolescents. By focusing on sex differences, this study analyzes female as well as male behavior problems. The data used in this study are gathered from 1,046 middle and high school students in a national sampling. The results are as follows. Internet addiction is the most frequently occurring problem. A chi-square test shows that male students have higher experience rates than female students in obscene chatting and violent games. A series of logistic regressions are performed to blow the relative influence of independent variables controlling for each other. In the case of male students' internet behavior problems, region, communications with their parents, interactions with their close friends, and satisfaction with community facilities are significant variables. Interactions with friends are significant in predicting behavior problems of both female and male students. Suggestions and implications with regard to intervention strategies for adolescents are discussed.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.3
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• pp.238-243
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• 2001

Purpose : The purpose of this study was to determine radiologic variables affecting extraction of impacted mandibular third molar. Materials and Methods : This study was investigated on 44 consecutive extractions of unilateral impacted mandibular third molars (Male;34, Female;10, Mean age;24.98, Age range;19-35). Fourteen radiologic variables, which were actual value except only one, were evaluated to establish their relation to the operation time. The Pearson correlation coefficient and Stepwise procedures for regression analysis were carried out. Results : Eight variables (depth, angulation, ramus width, relationship to the second molar, distal ramus depth, mesial ramus depth, mesial periodontal ligament width and follicle) showed a statistically significant relation to the operation time(Pearson correlation coefficient, p<0.05). Two variables, depth and mesial periodontal ligament width, showed the most powerful and just relation to the operation time($r^2$ = 0.349, p<0.05). Conclusion : This study shows that our results can help general practioner to estimate the operation time of extraction of impacted mandibular third molars by measuring two radiologic variables ; depth and mesial periondontal ligament width.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.5
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• pp.653-660
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• 2007

The purpose of this study was to measure the causal relationships among such variables as moral concerns for animals, meat texture, meat color, satiety from meat, disgust with meat and pork consumption. A total of 250 questionnaires were completed. Structural equation models were used to measure the causal effects of the constructs. The study outcomes demonstrated that the structural analysis results of the data were an excellent model fit. The effects of moral concerns for animals, meat texture and satiety from meat on the disgust with meat were statistically significant. As expected, disgust with meat had a significant effect on pork consumption. Moreover, moral concerns for animals and satiety from meat had a significant indirect effect on pork consumption through disgust with meat. Also, satiety from meat alone had a significant indirect effect on pork consumption through disgust with meat. By developing and testing conceptual models that integrated the relationships among ideational variables, sensory affective variables, anticipated consequences variables, emotional variables, and behavioral variables, this study may approach a deeper understanding of the complex relationships among pork consumption-related variables. A greater understanding of these complex relationships can improve the managerial diagnosis of problems as well as opportunities for different marketing strategies, including pork production and pork product development, and marketing communications.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.303-310
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• 2010

The purpose of this study was (a)to compare electromyographic (EMG) activities and physiological variables on the development of fatigue induced by ergometer test, (b)to determine investigate the differences in the stage of fatigue between the electromyographic characteristics and physiological variables. Nine male university students who have no musculoskeletal disorder were recruited as the subjects. The electromyographic characteristics(peak IEMG, average IEMG, median frequency, mean edge frequency) and physiological variables(HR, RPE, blood lactate) were determined for each stage(15, 30, 45, 60 minutes, all out). For each dependent variable, one-way analysis of variance(ANOVA) with repeated measures and correlation analysis were performed to test if significant difference existed(p<.05). The results showed that peak IEMG, average IEMG from low extremity and physiological variables were significantly increased during the all-out stage. EMG parameters in VL, VM show significantly correlation with physiological variables during whole stages. This indicated that IEMG values may be proper parameters to determine muscle fatigue rather than physiological variables.

• Journal of the Korean Home Economics Association
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• v.39 no.6
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• pp.61-78
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• 2001

The objectives of this study were to examine the propensity of job related variables, self-esteem, overall job satisfaction, satisfaction about six categories in the job(task, boss, payment, co-workers, promotion, job environment) of life insurance planners, to investigate the effects of self-esteem, demographic variables, job characteristics variables on the overall job satisfaction and the satisfaction of six categories in the job. The survey of this study was conducted by means of self-administered questionnaire with 275 life insurance planners located in Taegu. Major findings were as follows:(1) The propensity of self-esteem and overall job satisfaction of life insurance planners averages 3.75 and 3.35 points(5 Likert scale). The propensity of satisfaction about task, boss, payment, co-workers, promotion, job environment of life insurance planners averages 4.22, 2.67, 1.68, 2.09, 1.71, 2.65 points separately(5 Likert scale). (2) According to the results for examining the relative influences of variables affecting overall satisfaction of life insurance planners, the relative importance of related variables are in the order of , self-esteem in the job, social dignity of the job, the prospect about the dignity of life insurance planner, the motive of having job. Explanatory power of these variables totaled 43.5%.