• Bulletin of the Korean Mathematical Society
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• v.52 no.5
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• pp.1423-1431
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• 2015

A clique-transversal set D of a graph G is a set of vertices of G such that D meets all cliques of G. The clique-transversal number is the minimum cardinality of a clique-transversal set in G. For every cubic graph with at most two bridges, we first show that it has a perfect matching which contains exactly one edge of each triangle of it; by the result, we determine the exact value of the clique-transversal number of line graph of it. Also, we present a sharp upper bound on the clique-transversal number of line graph of a cubic graph. Furthermore, we prove that the clique-transversal number of line graph of a triangle-free graph is at most the chromatic number of complement of the triangle-free graph.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.19-26
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• 2015

This paper proposes a design method for improving the frequency-domain performance reliability of dynamic systems with uncertain and degrading components. Discrete frequencies are used in this method as surrogates for the frequency band of interest, and the conformance of the frequency responses to the specification at these frequencies is utilized to model the frequency-domain performance reliability. A meta-model for the frequency responses, an extreme-value event, and the set-theory are integrated to improve the computational efficiency of the reliability estimation. In addition, a sample-based approach is presented to evaluate and optimize the estimated performance reliability. A case study of a vibration absorber system showed that the proposed design method has engineering applications.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.2
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• pp.137-145
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• 1990

Six commercial rice varieties were cultivated at different locations in 1987 and 1988. Rice samples harvested from 8 to 20 locations for a variety each year were used to measure or observe grain appearance, amylose content and alkali digestibility, cooked rice texture using rheometer, gelatinization and viscosity of rice flour using amylograph, and eating Quality of cooked rice by sensory evaluation. Relationship between Quality characteristics showing large locational variation were analized to approach the long-term objective, rice grain Quality standardization. Percent white-center and white-belly grain of the same variety showed great variation between locations, but did not affect on 1000-grain weight, amylose content and alkali digestibility, amylogram and rheogram characteristics, and eating Quality of cooked rice. Positive correlationship were obtained between maximum viscosity and break down, and maximum viscosity and alkali digestibility. Set back was correlated negatively with maximum viscosity, break down and alkali digestibility. Rice samples having significantly lower values of maximum viscosity and break down and higher set back value at the same time showed higher ADV and lower texture palatability index (TPI) and viscousness/hardness ratio (Vi/H), and lower sensory evaluation score of cooked rice compared with those of rices having typically higher values of maximum viscosity and break down and lower set back value. When TPI, Vi/H and overall sensory eating score of cooked rices measured were divided into three categories, high, medium and low using deviation from locational mean value of a variety, many of rice samples having high TPI or high Vi/H showed medium or high in overall sensory eating score of cooked rice.

• Tuberculosis and Respiratory Diseases
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• v.86 no.3
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• pp.203-215
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• 2023

Background: Surgical resection is the standard treatment for early-stage lung cancer. Since postoperative lung function is related to mortality, predicted postoperative lung function is used to determine the treatment modality. The aim of this study was to evaluate the predictive performance of linear regression and machine learning models. Methods: We extracted data from the Clinical Data Warehouse and developed three sets: set I, the linear regression model; set II, machine learning models omitting the missing data: and set III, machine learning models imputing the missing data. Six machine learning models, the least absolute shrinkage and selection operator (LASSO), Ridge regression, ElasticNet, Random Forest, eXtreme gradient boosting (XGBoost), and the light gradient boosting machine (LightGBM) were implemented. The forced expiratory volume in 1 second measured 6 months after surgery was defined as the outcome. Five-fold cross-validation was performed for hyperparameter tuning of the machine learning models. The dataset was split into training and test datasets at a 70:30 ratio. Implementation was done after dataset splitting in set III. Predictive performance was evaluated by R² and mean squared error (MSE) in the three sets. Results: A total of 1,487 patients were included in sets I and III and 896 patients were included in set II. In set I, the R² value was 0.27 and in set II, LightGBM was the best model with the highest R² value of 0.5 and the lowest MSE of 154.95. In set III, LightGBM was the best model with the highest R² value of 0.56 and the lowest MSE of 174.07. Conclusion: The LightGBM model showed the best performance in predicting postoperative lung function.

• Korean Management Science Review
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• v.23 no.1
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• pp.75-85
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• 2006

The rectilinear Steiner tree problem (RSTP) is to find a minimum-length rectilinear interconnection of a set of terminals in the plane. It is well known that the solution to this problem will be the minimal spanning tree(MST) on some set Steiner points. The RSTP is known to be NP-complete. The RSTP has received a lot of attention in the literature and heuristic and optimal algorithms have been proposed. A key performance measure of the algorithm for the RSTP is the reduction rate that is achieved by the difference between the objective value of the RSTP and that of the MST without Steiner points. A hybrid evolutionary strategy on RSTP based upon nodes set is presented. The computational results show that the hybrid evolutionary strategy is better than the previously proposed other heuristic. The average reduction rate of solutions from the evolutionary strategy is about 11.14%, which is almost similar to that of optimal solutions.

• Bulletin of the Korean Mathematical Society
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• v.59 no.1
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• pp.167-177
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• 2022

A vertex v of a graph G = (V, E) is said to ve-dominate every edge incident to v, as well as every edge adjacent to these incident edges. A set S ⊆ V is called a double vertex-edge dominating set if every edge of E is ve-dominated by at least two vertices of S. The minimum cardinality of a double vertex-edge dominating set of G is the double vertex-edge domination number γ_dve(G). In this paper, we provide an upper bound on the double vertex-edge domination number of trees in terms of the order n, the number of leaves and support vertices, and we characterize the trees attaining the upper bound. Finally, we design a polynomial time algorithm for computing the value of γ_dve(T) for any trees. This gives an answer of an open problem posed in [4].

• Fashion & Textile Research Journal
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• v.12 no.1
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• pp.60-67
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• 2010

The purposes of this study were to investigate the impacts of shopping value, customer satisfaction, and switching barrier on consumer loyalty to website. For this purpose, the study tested covariance structural model which set relationships among independent variable(shopping value), meditated variables(customer satisfaction and switching barrier), and dependent variable(website loyalty). The data were collected from a sample of 239 internet shopper of college female students. The covariance structural model and research hypothesis analyzed by using SPSS 16.0 and AMOS 5.0 program. The results are as follows: First, the structural model is accepted significantly. Second, shopping value had a positive influence on customer satisfaction and switching barrier. Third, shopping value, shopping satisfaction of customer, and switching barrier had a positive impact on website loyalty. Forth, shopping value had a positive impact on website loyalty directly, it was found to have a indirect effect on website loyalty through customer satisfaction and switching barrier.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.143-146
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• 2004

In a situation that rank order information on attribute weights is captured, two solution approaches are presented. An exact solution approach via interaction with a decision-maker pursues progressive reduction of a set of non-dominated alternatives by narrowing down the feasible attribute weights set. In approximate solution approach, on the other hand, three categories of approximate methods such as surrogate weights method, the dominance value-based decision rules, and three classical decision rules are presented and their efficacies in terms of choice accuracy are evaluated via simulation analysis. The simulation results indicate that a method, which combines an exact solution approach through interactions with the decision-maker and the dominance value-based approach is recommendable in a case that a decision is not made at a single step under imprecisely assessed weights information.

• Journal of Nutrition and Health
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• v.31 no.9
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• pp.1508-1521
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• 1998

The purpose of this study was to analyze and evaluate the menu served in business & industry contract foodservice by assessing nutritional value and by using menu-engineering technique from managers' view point. CAN-Pro program and Kasavana k Smith's Menu Engineering technique were used to evaluate the nutritional value and menu analysis, respectively. The data were analyzed using the SAS package program for descriptive analysis, t-test, ANOVA, and Pearson Correlation Analysis. As the result of nutritional value of lunch menu, all nutrient contents per meal were higher than a third of Korean recommended dietary allowances(RDA), But there was no problem when 20∼30% of plate waste was considered. Carbohydrate : Protein fat ratio was 62.7 : 16.4 : 20.8. Because animal : vegetable source ratios of protein, fat, calcium, iron were 44 : 56, 42 : 58, 22 : 78, 24 : 76, respectively, animal sources of calcium and iron needed to be supplemented. Plural set menus of A site were classified as STAR, PUZZLE, PLOWHORSE, DOG by Menu engineering technique. Set menus and soups & pot-stews among cafeteria menus in C site were operated properly without DOG and PUZZLE item. Side dishes of fishes, meats 8t eggs among cafeteria menus in C site were, for the most part, classified as STAR item, and side dishes of vegetables & salads and noodles among cafeteria menus in C site were STAR, PUZZLE, and DOG items. (Korean J Nutrition 31(9) : 1508-1521, 1998)

• Journal of the Korean Society for Railway
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• v.15 no.3
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• pp.278-285
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• 2012

The Service Availability (SA) in the viewpoint of passenger is used as the key performance indicator (KPI) of quality of service in Light Rail Transit (LRT) Public-Private Partnerships projects. But there are many disputes on the target value of SA because of the lack of experience in SA. The target value of SA should be set at an early stage of the project to be specified on the system specifications and operation plan. Therefore, this paper developed the quantitative prediction model of SA to set the reasonably achievable target value of SA at an early stage of the LRT project. Also this paper analyzed the relationship and differentiation of SA and Train Punctuality (TP) that is mostly compared with SA.