• 한국정밀공학회지
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• 제15권9호
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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.

• 대한금속재료학회지
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• 제47권12호
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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.

• 한국분무공학회지
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• 제9권3호
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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.

• 대한가정학회지
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• 제37권3호
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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.

• 한국학교ㆍ지역보건교육학회지
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• 제19권2호
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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.

• 대한지역사회영양학회지
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• 제24권1호
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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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• 제60권2호
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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.

• 한국콘텐츠학회논문지
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• 제13권3호
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• pp.174-183
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• 2013

본 연구는 한부모여성가구주의 인구사회학적 변인 및 경제적 스트레스가 삶에 질 즉 경제적 만족도와 신체적 건강상태 그리고 심리적 디스트레스가 어떻게 영향을 미치는가를 분석하였다. 연구대상은 전국 모자보호시설에 거주하는 430명의 표본을 분석자료 활용했다. SAS 9.1(Statistical Analysis System)을 이용하여 한부모여성가구주의 인구사회학적 특성을 설정된 연구모형에 의해 분석한 결과, 경제적 만족도, 신체적 건강상태, 심리적 디스트레스 즉 삶의 질에 부정적인 영향을 미치는 것으로 나타났다. 또한 한부모여성가구주가 경험하는 경제적 스트레스는 그들의 삶의 질에 부정적인 영향을 미치는 것으로 파악되었다. 특히 심리적 디스트레스에 가장 큰 영향력을 미치는 것으로 나타났으며, 경제적 만족도와 신체적 건강 상태에도 유의미한 영향을 미치는 것으로 나타났다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 춘계학술대회
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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.

• 한국유체기계학회 논문집
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• 제14권6호
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• pp.18-25
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• 2011

A boundary-layer pump with a single disk has been experimented to obtain its characteristic curve by changing the impeller of a centrifugal pump to a single disk. The primary objective to use of these types of pumps is to avoid hurting water life during transportation unnecessarily. The change of impeller should degrade the performance of pump, so we used the method to increase the roughness on the disk with sandpaper and mesh. The enhancement of shear force from the rotation of disk to the internal flow brought an augmentation of momentum transport, and the characteristics were far improved from the original single-disk pump without decreasing the survival rate of water life in the case of Pseudobagrus fulvidraco (bullhead fish). However, in the case of Artemia cyst (zooplankton), the survival rate was very degraded due to the micro scale smaller than turbulent eddy size. The result of this study could be used for the design of transportation and bio-filtering of water lying on a specific bandwidth of its scale of size.