• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1358-1368
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• 2006

This paper proposes a Pareto artificial life algorithm for solving multi-objective optimization problems. The artificial life algorithm for optimization problem with a single objective function is improved to handle Pareto optimization problem through incorporating the new method to estimate the fitness value for a solution and the Pareto list to memorize and to improve the Pareto optimal set. The proposed algorithm was applied to the optimum design of a journal bearing which has two objective functions. The Pareto front and the optimal solution set for the application were presented to give the possible solutions to a decision maker or a designer. Furthermore, the relation between linearly combined single-objective optimization problem and Pareto optimization problem has been studied.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.43-49
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• 1998

The deep hole drilling has an increasing demands because of its wide range applications and its good productivity. The BTA drills are capable of machining for having a large length to diameter ratio in single pass to higher degree of accuracy and surface finish. It's really necessary that the investigation for the deep hole drilling by the BTA drill because its required quality should be satisfied with single pass. This thesis deal with the experimental results obtained during single tube BTA system machining on SM55C steel for different machining conditions. The results of the investigation on the optimum cutting condition selecting and tool life reveals as follows. (1) The optimum cutting condition was cutting speed, V = 42 m/min and feed speed. F = 90 mm/min and the tool life was about 10 meters. (2) Surface roughness was $12\mum$ and the roundness was less using $16mum$single edge BTA drill in testing cutting condition.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.834-841
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• 2009

A study on the welding of electrogalvanized TRIP (Transformation-Induced Plasticity) steels was done to compare the life of the electrode and the alloying phenomena on the electrode tip surface using singlephase AC and inverter-DC resistance welding processes. A longer life of the electrode (>200 welds) was achieved using the inverter-DC welding process. The tensile shear strength was higher in the electrode life test when welded with the inverter DC welding machine it maintained a higher value even when the welding nugget diameter was smaller than specified. When spot-welding was conducted using the single-phase AC welding process, a higher wear rate of the electrode was observed compared to that with the inverter-DC process. An alloying layer used to determine the rate of electrode growth showed differences in the metallurgical features of the surface alloying and Zn penetration depending on whether the single-phase AC process or the inverter-DC welding process was used. Moreover, changes in the dynamic resistance during the electrode life test were correlated with the electrode wear (or growth) rate.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.29-34
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• 2004

To investigate characteristics and micro-explosion of single-droplets of emulsified fuel, water is mixed with diesel oil by using ultrasonic energy fuel feeding system. The fuel characteristics is analysed through H-NMR spectrum and micro-explosion phenomena of the emulsified fuel is also investigated. The life times of droplets of conventional diesel fuel, ultrasonic energy added diesel fuel and emulsified fuel we obtained additionally. According to this study, the micro-explosion phenomena of single-droplets happen in atmospheric pressure condition, a curve form of emulsified fuel's life tim is different from diesel fuel's one and the change of chemical structures is a cause of ultrasonic-energy-added diesel fuel effect.

• Journal of the Korean Home Economics Association
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• v.37 no.3
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• pp.127-142
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• 1999

The purposes of this research were to develop a family life education program for single-parent families in rural area and to investigate the effectiveness of education through continuous tests.For these objectives, the concurrent-type program for single-parent families that emphasized communication skills, psychological strategies, and the importance of social support system was constructed. The effectiveness of the program was evaluated by pre-, post- and delayed test through 88 single parents and their children and it was analyzed by paired t-test. The results suggested that the program was effective in improving self-esteem, self-confidence and in decreasing depression. This effectiveness was more in single-father families than single-mother families. But especially in children this effectiveness was diminished as times passed. For maintaining this effectiveness in program, more frequent and continuous following education was demanded.

• The Journal of Korean Society for School & Community Health Education
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• v.19 no.2
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• pp.43-52
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• 2018

Objects: In this study, we analyzed the correlation between stress and depression related to the quality of life of one elderly household, and analyzed the influence of stress and depression on the quality of life. In this study, I tried to make a plan for improving the quality of life for one elderly. Methods: In this study, the frequency and percentage according to the general characteristics of one elderly household were frequency analyzed. And the mean and standard deviation of stress, depression, quality of life were analyzed on average. And continuous analysis of stress, depression, quality of life, etc., conducted a technical analysis. Relationship to stress, depression, quality of life, correlation analysis was done. The effect of stress and depression on the quality of life was linear regression analysis. SPSS Version 23.0 was used for analysis. Result: Increased stress and increased depression in elderly single households was a static (+) correlation. And the results of the regression analysis showed that the higher the stress and depression of one elderly household, the lower the quality of life. Conclusion: For the improvement of the quality of life of one elderly household, the government should support stress and depression prevention programs according to sex, age, number of chronic diseases.

• Korean Journal of Community Nutrition
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• v.24 no.1
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• pp.1-17
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• 2019

Objectives: This study was performed to compare the dietary life of single- and non single-person households in the Korea National Health and Nutrition Examination Survey (KNHANES). Methods: A nationally representative sample of 20,421 19-64-year-olds who had 24-hour recall data was taken from the 2014-2016 Korea National Health and Nutrition Examination Survey (KNHANES). Single- and non single-persons were compared for nutrient intake, dietary behaviors, food consumption patterns, nutrition education and confirm nutrition label. Results: The dietary intakes of dietary fiber and iron were lower in single-person households than in non single-person households. The lower the level of education and income, the lower the nutrient intake of single-person households. In the case of those aged 19 to 29, the breakfast skipping rate was higher in single-person households than in non single-person households. The higher the education level, the higher the breakfast skipping rate and the eating out frequency in the single-person households. In the food intake survey, the frequency of healthy food intake in single-person households was much lower than that of non single-person households. The confirmation rate of nutrition labeling was lower in single-person households than in non single-person households. Conclusions: This study shows that single-person households have poorer health-nutritional behaviors than multi-person households. Therefore, a nutrition education program based on the data of this study needs to be developed for health promotion of single-person households.

• Human Ecology Research
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• v.60 no.2
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• pp.163-176
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• 2022

The purpose of this study is to understand the changes in the daily life and quality of life of the elderly due to the spread of COVID-19. This study attempted to supplement the limitations of quantitative analysis by performing both quantitative and qualitative analysis. A large-scale representative data, the Elderly Survey 2017 and 2020, were analyzed, and in-depth interviews were conducted with a total of 16 elderly people in Gwangju and Seoul. As a result, it was found that the overall quality of life was positively changed compared to before Corona. The frequency of contact and visits with family members decreased whereas the time spent watching TV increased. The elderly's adaptation to daily life has a series of processes since the first outbreak of COVID-19. At the beginning of the outbreak, there were fear, anxiety, and depression due to isolation, but gradually made efforts to adapt to the new situation. They reported that they realized the importance of human relationships, especially spouses, in a crisis situation and that there were some positive aspects as well. Finally, in all these results a difference was found between single-person households and multi-person households. Through the above research results, academic and policy measures were discussed.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.174-183
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• 2013

This study in the lives of single-parent female households demographic and economic variables and economic stress quality financial satisfaction and physical health status and psychological distressed affect were analyzed. The study took advantage of an analysis of a sample of 430 people living in care facilities nationwide cap material. Using SAS 9.1 (Statistical Analysis System) were analyzed by the research model to set a single-parent female head of household demographic and economic characteristics, economic satisfaction, physical health status, was found to have a negative effect on the quality of life psychologically distressed. Also was identified as a single-parent female households experience economic stress have a negative effect on their quality of life. Especially, showed the biggest influence on the psychologically distressed was a significant influence financial satisfaction and physical health status in.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.71-71
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• 2019

The genus Cenchrus (Poaceae), containing ca. 23 species, is distributed throughout Australia, Africa, Indian sub-continent, and America. In Korea, Cenchrus longispinus (Hack.) Fernald, especially introduced to Daecheong Island in 1999, is one of the most hazardous invasive plant which causes serious environmental threats, biodiversity damages and physically negative impact on humans and animals. Based on the next-generation sequencing (NGS) technology, we characterized the chloroplast (cp) genome sequences of C. longispinus which contains a large single copy (LSC; 80,223 bp), a small single copy (SSC; 12,449 bp), separated by a pair of inverted repeats (IRs; 22,236 bp). Additionally, we analyzed the cp genome sequences of Cenchrus echinatus L. which contains a large single copy (LSC; 80,220 bp), a small single copy (SSC; 12,439 bp), separated by a pair of inverted repeats (IRs; 22,236 bp). These cp genomes consist of 75 unique genes, 4 rRNA coding genes, 33 tRNA coding genes and 21 duplicated in the IR regions, of which the gene content and organization are similar to the other Poaceae cp genomes. We selected 40 potential regions in cp genomes of two Cenchrus species and one Korean Pennisetum species to develop new single nucleotide polymorphism (SNP) markers for identifying C. longispinus based on amplification-refractory mutation system (ARMS) technique. The markers, inferred from SNP in matK and ndhF genes, show effectiveness to recognize C. longispinus from C. echinatus and Korean native species Pennisetum alopecuroides (L.) Spreng.