• Journal of the Korean Society of Combustion
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• v.9 no.3
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• pp.19-26
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• 2004

This paper presents results of experimental study of flame chemiluminescence from turbulent premixed flames in a dump combustor. A detailed spectroscopic measurement of chemiluminescence over the wavelength of 405-495 nm is made for various flow conditions. No effect of turbulence on the relationship between chemiluminescence and heat release is found, suggesting the overall chemiluminescence intensity collected be used as a measure of overall heat release for non-oscillating stable flame. The background-$CO_2^*$ subtracted $CH^*$ chemiluminescence is found to be more sensitive to the equivalence ratio and premixedness of fuel-air mixture than $CO_2^*$ chemiluminescence.

• The Journal of the Korea Contents Association
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• v.19 no.11
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• pp.122-131
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• 2019

This study analyzed the moderating effect according to school levels in the structural relationship between stressful interpersonal relationships at work and rumination in teachers' depression. For this study, a research model was formed based on theoretical understandings and a literature review. The researchers surveyed 811 teachers at primary and secondary schools to measure scales of depression, rumination, and stress in interpersonal relationships at work. Primary education and secondary education were the grouping variables for the school levels, and the collected data was analyzed using multi-group structural equation modeling. Also, to affirm equivalence between the two models, the data was investigated using the constrained model of measurement equivalence. The research results verified the equivalence between the two models and the moderating effect by comparing the path coefficients of the two models on the assumption of equivalence constraint. As a result, the moderating effect according to school levels was revealed on the path from stressful interpersonal relationships at work to depression. Grounded on this analysis, stress in interpersonal relationships at work mediates the impact of rumination in teachers' depression. In addition, the research revealed that the moderating effects on stressful interpersonal relationships at work varied according to school level, and the moderating effect of stress in interpersonal relationships at work affected middle school teachers but not primary school teachers.

• Journal of Korean Academy of Nursing
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• v.39 no.6
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• pp.781-787
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• 2009

Purpose: The purpose of this study was to evaluate a computerized touch-screen version of the asthma-specific quality-of-life (cA-QOL) questionnaire against the conventional paper-and-pencil version (pA-QOL) for equivalence, time for completion, user preference, and ease of use. Methods: A total of 261 patients were recruited. A randomized cross-over design was used. Patients in group A completed the cA-QOL first while waiting to see a physician, and completed the pAQOL version after seeing the physician. Patients allocated in group B completed these questionnaires in the reverse order. The patients were asked questions about user preference and ease of use of the cA-QOL. The time taken to complete both versions of the questionnaire was measured. Results: Weighted kappa coefficients of all items showed almost perfect agreement. The time required to complete the pA-QOL is faster than the time for cA-QOL. The patients who preferred the cA-QOL were 37.5%, while those who preferred the pA-QOL were 29.9%. Most patients reported that the cA-QOL was "easy" or "very easy" to complete. Conclusion: The cA-QOL is the computerized equivalent of the pA-QOL. The findings herein demonstrate that the cA-QOL can be helpful to nurses in busy practices for assessing, collecting, and evaluating their patients' health related quality of life.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.37-42
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• 2010

The measurement of heat release rate is of great importance in the study of thermo-acoustic instability occurring in lean premixed combustion and the chemiluminescence emission has been used as an indicator of heat release in combustion instability studies primarily for its relative simplicity. This paper presents results of experimental study of flame chemiluminescence from an atmospheric, swirl-stabilized, turbulent lean premixed flame with a main emphasis on the effect of $CO_2^*$ background level in the $CH^*$ and $OH^*$ band. The test results show that the effect of $CO_2^*$ level in the $CH^*$ band is greater than that in the $OH^*$ band. Also, the background to peak ratio for both $CH^*$ and $OH^*$ bands can be expressed as a function of equivalence ratio, almost regardless of a change in the inlet velocity.

• Child Health Nursing Research
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• v.15 no.4
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• pp.335-342
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• 2009

Purpose: This study, using a pre-post test design of non-equivalence comparative group, was done to determine effects of Kangaroo care (KC) on growth in premature infants and on maternal attachment (MA). Methods: Fifty-three premature infants were assigned to the KC (24) or control group (CG) (29). Data were collected from July 2007 to June 2008. KC was given for 60 min at a time, Monday, Wednesday, and Friday for 10 times. Weight, height, and head circumference (HC) of premature infants were checked before the program started. Following the initial measurement, the program was given and measurements were taken again at the end of the program. For measurement of attachment between mother and infant, data collection was done using structured self-reported questionnaires. Results: KC group had a higher weight (t=2.565, p=.013), height (t=2.182, p=.034) and HC (t=2.468, p=.017) than the CG. Compared to the CG, the KC had significantly higher scores in MA (t=2.026, p=.048). Conclusion: The results of this study suggest that the practice of KC in the nursing environment might actively promote attachment between mother and infant as well as acceleration of growth for premature infants as one of the most efficient nursing intervention.

• Journal of the Korean Society of Combustion
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• v.22 no.3
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• pp.35-40
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• 2017

Jet aviation fuel is one of liquid fuel which are used in aircraft engines. Korean domestic jet fuel, called Jet A-1, is tested for measurement of ignition delay time by using a shock tube manufactured recently. The temperature varies from 680 to 1250 K and the pressure and equivalence ratio of Jet A-1/air are fixed 20 atm and 1.0, respectively, for this experiment. The ignition delay time data of Jet A-1 are compared with those of Jet A, which has similar properties to Jet A-1. The behavior of negative-temperature-coefficient (NTC) is observed in the temperature range 750-900 K. In addition, ignition delay time of iso-octane is measured, which is one of the surrogate components for jet aviation fuel. The experimental data are compared and validated with the previous results from the literatures. A surrogate fuel for the present Jet A-1 consists of 45.2% n-dodecane, 32.1% iso-octane, and 22.7% 1,3,5-trimethylbenzene. The predicted ignition delay time for the surrogate agrees well with the measured one for Jet A-1.

• Journal of Korean language education
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• v.28 no.4
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• pp.87-119
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• 2017

The purpose of this study is to classify research methods used in Korean language education studies with a focus on identifying how and what quantitative research methods are utilized in these studies. Analyzing articles published in the Journal of Korean Language Education from 2005 to 2016, we found a trend that as a replacement for secondary research, primary research played a more prominent role after 2010, as the number of quantitative studies and studies using mixed methods increased. We also found that within quantitative studies of Korean language education, research themes and statistical analyses became diversified after 2010. In order for quantitative research to contribute continuously to Korean language education, the quality of research has to improve. In particular, quantitative researchers in this area should: (a) increase their general understanding of statistical methods, (b) conduct "power analysis" to determine the appropriate sample size for hypothesis testing, and (c) be aware of measurement issues such as measurement equivalence and DIF when measuring latent psychological constructs. It is also important to notice that these points above should be considered carefully in the planning and designing stage for researchers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.187-199
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• 2011

The main objective of this study was investigation of natural gas flames in a lean premixed swirl-stabilized dump combustor with an attention focused on the effect of the various fuel-air mixing section geometry on the combustion instability characteristics. The multi-channel dynamic pressure transducers were located on the combustor and inlet mixing section region to observe combustion pressure oscillation and difference phase at each dynamic pressure measurement results. Dynamic pressures were also measured to investigate characteristics of combustion at the same time. The combustor and mixing section length was varied in order to have different acoustic resonance characteristics from 800 to 1800 mm in combustor and 470, 550, 870 mm in mixing section. We observed two dominant instability frequencies in this study. Lower frequencies were obtained at lower equivalence ratio region and it was associated with a fundamental longitudinal mode of combustor length. Higher frequencies were observed in higher equivalence ratio conditions. It was related to secondary longitudinal mode of coupled with the combustor and mixing section. In this instability characteristics, pressure oscillation of mixing section part was larger than pressure oscillation of combustor. As a result, combustion instability was strongly affected by acoustic characteristics of combustor and mixing section geometry.

• Journal of ILASS-Korea
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• v.10 no.2
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• pp.1-9
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• 2005

An experimental study was carried out to obtain the fundamental data about the effects of radical ignition on premixture combustion. A CVC(constant volume combustor) divided into the sub-chamber and the main chamber was used. Numerous narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in tile sub-chamber derives the simultaneous multi-point ignition in the main chamber. We have examined the effects of the sub-chamber volume, the diameter and number of passage holes, and the equivalence $ratio({\Phi})$ on the combustion characteristics by means of burning pressure measurement and flame visualization. In a CVC, the overall burning time including the ignition delay became very short and the maximum burning pressure was slightly increased by the radical ignition(RI) method in comparison with those by the conventional spark ignition(SI) method. Combustible lean limit by RI method is extended by ${\Phi}=0.25$ compared with that by SI method. Also, In cases of charging the number and the diameter for the fixed total cross section of the passage holes, combustion period increased significantly at a sub-chamber with a single hole, but those of the other conditions had almost a similar tendency in the sub-chamber with 4 or more holes. regardless of equivalence ratio. Therefore, it was Proved that a critical cross section exists with the number of passage holes.

• Fashion & Textile Research Journal
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• v.17 no.4
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• pp.574-587
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• 2015

This quantitative study helps develop a measurement tool for consumer experiences inside and outside of a fashion brand store in a large shopping center along with a previous qualitative study that utilized a consumer interview. An expert group interview was conducted to verify the result of the previous qualitative study. Subjects were selected through convenient sampling. A self-administered questionnaire was developed to collect the data. We used 666 questionnaires for data analysis. To analyze data, reliability analysis, factor analysis, correlation analysis and measurement equivalence verification were conducted with a statistical package of SPSS 21.0 and Amos 18.0. We used 27 questions in 8 factors for consumer experience inside of the fashion brand store: fashion product, VMD, salesperson responsiveness, salesperson specialty, salesperson's special treatment, salesperson's respect for customers, and positive/negative emotion. We used 27 questions concerning seven factors for the consumer experience outside of a fashion brand store that encompasses a large shopping center: experience with brand and product category diversity, experience with promotion and event, esthetic experience, experience with culture and entertainment, experience with recreational behavior, experience with reputation and sense of pride, and experience with customers.