• 대한기계학회논문집A
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• 제39권12호
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• pp.1199-1206
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• 2015

본 연구는 경유와 바이오디젤(대두유) 혼합연료의 디젤엔진 배기특성을 조사하였고, 연료 혼합비는 BD(biodiesel)3, BD5, BD20, BD50 및 BD100이며, 분사압력 조건을 400 bar, 600 bar, 800 bar, 1000 bar 및 1200 bar로 변화시켰다. 그리고 연료 혼합비 및 분사압력에 따른 엔진배출물인 NOx와 Soot의 정량적인 분석을 위해 통계학에 기초한 피어슨 상관계수와 스피어만 상관계수를 이하였다. 본 연구의 결과로서 실험변수인 혼합비와 분사압력에 대한 NOx 및 Soot 발생량의 피어슨 상관계수는 -0.811이며, 스피어만 상관계수는 -0.884로 NOx와 Soot 발생량 관계가 선형적이며, 이것은 trade-off관계를 나타낸다. 또한 각각의 분사압력 조건에서 피어슨 상관계수가 음의 상관 관계를 나타내며 이것은 NOx와 Soot 배출관계가 반비례적인 것을 나타낸다.

• 동력기계공학회지
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• 제19권1호
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• pp.56-63
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• 2015

In this study, the exhaust characteristics of the diesel engine for the change of the mixing ratio of biodiesel fuel were quantitatively analyzed by using the numerical analysis method. As the fuel used in the experiment, the diesel and biodiesel(waste oil, soybean oil), the mixed fuel BD2(Diesel only), BD3, BD5, BD20, BD50 and BD100 were used. The injection pressure($p_{inj}$) was set to 400bar, 600bar, 800bar, 1000bar and 1200bar as the experimental variable. Also the concept of the standard deviation, Pearson's correlation coefficient and Spearman rank-order correlation coefficient based on the statistics was introduced in order to analyze the exhaust characteristics of the quantitative NOx and Soot according to the injection pressure and the mixing ratio variation of biodiesel blending fuel. It is considered that as a result of studies, for the waste oil, NOx and Soot can be simultaneously reduced through control of the mixing ratio at the regions of $p_{inj}=400bar$ and $p_{inj}=600bar$, and the Soot can be reduced without affecting on the emission of NOx at more than $p_{inj}=800bar$. For the soybean oil, NOx and Soot can be simultaneously reduced at $p_{inj}=400bar$ and the Soot can be reduced without affecting on the emission of NOx at $p_{inj}=600bar$.

• 대한지역사회영양학회지
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• 제3권2호
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• pp.273-280
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• 1998

This study was designed to estimate the improvement of Validity for food frequency questionnaire(FFQ) by offering multiple choice portion size in developing a questionnaire. Validity of the two methods(food frequency questionnaire I=FFQ I & Food frequency questionnaire II=FFQ II) was tested in comparison with reference method of the 7-day weighed record(7DWR). Dietary consumption data of the three methods(FFQ I, FFQ II & 7DWR) were collected from 101 female university students for the analysis. Validity was measured in two categories : One was the nutrient intake value from the three methods, the other was the identification of between individual variation within the group. Spearman's rank order correlation test and distribution graphs were used for the analysis. The result showed that individual intake value of the FFQII was closer to that of the 7DWR than that of the FFQ I.Spearman's rank order correlation between the FFQII and the 7DWR did not show any improved correlation. The distribution graphs of nutrient intake derived from both the FFQ I and the FFQII were different from that of the 7DWR. Therefore, it could be suggested that single one portion size food frequency questionnaire is an equally efficient method as a multiple choice food frequency questionnaire to be adopted in epidemiologic studies.

• Journal of Astronomy and Space Sciences
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• 제23권3호
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• pp.167-176
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• 2006

We investigate the correlation between the peak energy and the burst duration using available long GRB data with known redshift, whose circumburst medium type has been suggested via afterglow light curve modeling. We find that the peak energy and the burst duration of the observed GRBs are correlated both in the observer frame and in the GRB rest frame. For our total sample we obtain, for instance, the Spearman rank-order correlation values ${\sim}0.75\;and\;{\sim}0.65$ with the chance probabilities $P=1.0{\times}10^{-3}\;and\;P=6.0{\times}10^{-3}$ in the observer frame and in the GRB rest frame, respectively. We note that taking the effects of the expanding universe into account reduces the value a bit. We further attempt to separate our GRB sample into the 'ISM' GRBs and the 'WIND' GRBs according to environment models inferred from the afterglow light curves and apply statistical tests, as one may expect that clues on the progenitor of GRBs can be deduced directly from prompt emission properties other than from the ambient environment surrounding GRBs. We find that two subsamples of GRBs show different correlation coefficients. That is, the Spearman rank-order correlation are ${\sim}0.65\;and\;{\sim}0.57$ for the 'ISM' GRBs and 'WIND' GRBs, respectively, after taking the effects of the expanding universe into account. It is not yet, however, statistically very much significant that the GRBS in two types of circumburst media show statistically characteristic behaviors, from which one may conclude that all the long bursts are not originated from a single progenitor population. A larger size of data is required to increase the statistical significance.

• 대한지역사회영양학회지
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• 제7권4호
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• pp.548-558
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• 2002

The purpose of this study was to develop a computer software program for nutritional assessment using a Semi-Quantitative Food Frequency Questionnaire (SQFFQs) and the 24-hour Recall Method. The software for the SQFFQ was divided into input, output, and database. For dietary analyses, recipe and food databases were used. The recipe database included 25 items and the food database was divided into 18 food groups. The food database was composed of 19 general nutrient items, 33 fatty acids, and 18 amino acids. The software developed in this study can be summarized as follows: 1) input items related to the individual s ages information, lifestyle, biological values, and dietary habits; 2) individualized data in percent of the Korean RDA, the energy ratios of carbohydrates, proteins and fats, the ratio of animal to plant source intakes, and the distribution of food group intakes; 3) Statistical data on the individual's information, lifestyle, biological values, and dietary intakes including the frequency of intake of cooked foods, the amounts of food, and the number of food groups, and nutrients. In the 24-hour Recall Method, the input and output consisted of the individual s information and cooked dish intakes. The individual s report included the amounts of nutrient intake according to number of meal and days, in comparison to the Korean RDA, the energy ratio for carbohydrates, proteins and fats, the ratio of animal to plant source intakes, and the distribution of food group intakes. The statistical report presented the number of food groups and foods, and the nutrient intakes. To evaluate the validity of the SQFFQ, the Spearman Rank Order Correlation and kappa values were used. As a result, correlation coefficients comparing the 24-hour Recall Method appeared to be more than 0.5, except for vitamin $B_1, B_2$, niacin, and vitamin E. The kappa values for energy and carbohydrate intakes were both 0.7, and protein, fat, vitamin C, folate, Ca, and iron intakes ranged from 0.3 to 0.7.

• 대한기계학회논문집B
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• 제38권2호
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• pp.129-137
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• 2014

본 연구에서는 바이오디젤연료 혼합비변화에 대한 디젤엔진의 배기특성에 대해 조사하였다. 실험에 사용된 연료는 경유와 바이오디젤(폐식용유) 혼합연료 BD3, BD5, BD20, BD50 및 BD100을 사용하였으며, 실험변수로서 분사압력(${\Delta}p_{inj}$)을 400bar, 600bar, 800bar, 1000bar 및 1200bar로 설정하였다. 분사압력과 바이오디젤 혼합연료 혼합비에 따른 정량적인 NOx와 Soot의 배기특성 해석을 위하여 통계학에 기초한 피어슨 상관계수와 스피어만 상관계수의 개념을 도입하였다. 본 연구의 결과로서 실험 조건 전체에 대한 피어슨 상관계수는 -0.732, 스피어만 상관계수는 -0.724로 NOx와 Soot 발생의 상관관계가 선형적이다. 특히 분사압력 800bar 조건에서 피어슨 상관계수가 -0.089으로 NOx와 Soot 배출량 상관관계가 0에 가깝기 때문에, 바이오디젤 연료 혼합비 제어를 통한 NOx와 Soot의 동시저감이 가능하다고 판단된다.

• 영어어문교육
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• 제9권1호
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• pp.131-152
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• 2003

The purpose of this study is to investigate the correlation between the introduction order of 9 English morphemes in the English textbook used in the middle school and the learning order of the morphemes by the 7th graders learning English as a foreign language. The subjects are 139 students in two middle schools, who learn English with different textbooks. The introduction order of each morpheme in two textbooks was examined according to its quantity and frequency. Data on the real learning order were collected through the written SLOPE test, and each morpheme was ranked by its group score. The introduction order of each morpheme in the textbook and the real learning order were analyzed by Spearman rank order correlation. It was shown that the correlation between the two was very low. This means that those textbooks do not take the learning order of English morphemes into account. Also it was shown that in the earlier stage of learning English the introduction order of each morpheme in the textbook had much influence on its learning order, but in the later stage such influence reduced gradually. This means that the learning order of English morphemes approaches the natural order as time passes by.

• 대한지역사회영양학회지
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• 제8권2호
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• pp.149-159
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• 2003

The purpose of this study was to develop and evaluate the validity of a food frequency questionnaire for Korean adolescents (FFQ-A) which could be used in clinical and epidemiological studies of the lifestyle and health of young people. The FFQ-A was designed to reflect the eating pattern of Korean adolescents, and was based on the 1998 Korean National Health and Nutrition Survey Reports. The FFQ-A had 25 (food categories. A total of 125 subjects (aged 13 to 15 years) was recruited from a randomly chosen middle school in a middle-income neighborhood in Anyang, South Korea. Each subject completed a FFQ-A, as well as a three-day dietary record. Data from 117 subjects (boys 47, girls 70) was used in the final analyses. Data on the nutrients was analyzed to estimate the Pearson correlations, Spearman rank-order correlations and agreement with categories. The validity of the FFQ-A was assessed relative to a three-day dietary record. The Pearson correlation coefficients for all the subjects were 0.94, 0.87, 0.77, 0.79, 0.49 and 0.68 for energy, carbohydrate, protein, fat, calcium, and iron, respectively. Similarly the Spearman rank-order correlation coefficients were 0.94, 0.85, 0.79, 0.81, 0.46, and 0.77 for energy, carbohydrate, protein, fat, calcium and iron, respectively. The Kappa values for energy, carbohydrate, protein, fat, calcium, and iron were 0.88, 0.67, 0.63, 0.67, 0.26, and 0.59, respectively. The percentage for misclassification of the lowest quartile into the highest quartile or vice versa ranged from 0% (energy, carbohydrate, or fat) to 16.7% (Vitamin C). Therefore the FFQ-A has a reasonable ability to assess the energy, carbohydrate, protein and fat intakes as estimated from a three-day dietary record of Korean adolescents. (Korean J Community Nutrition 8(2) : 142∼159, 2003)

• Journal of Applied Biological Chemistry
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• 제62권4호
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• pp.407-415
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• 2019

들깻잎에 살포된 triazole계 살균제 6종에 대하여 생물학적 반감기를 산출하고 분해 및 소실 속도를 확인하였으며, 통계분석으로 생물학적 반감기와 농약의 물리화학적 특성간의 상관관계를 확인하였다. 확립된 분석법으로 6종 농약의 회수율 시험 결과 84.8-104.9%로 잔류농약분석법 기준을 만족하였다. 들깻잎에 살포한 농약 6종의 생물학적 반감기는 first-order kinetics model으로 산출하였으며, 그 결과 6.4-15.1일로 나타났다. 산출된 생물학적 반감기와 6종의 농약의 물리화학적 특성을 주성분 분석으로 상관성을 확인하였을 때, pKa, Log P 및 생물학적 반감기가 PC1에 영향을 받아 상관성이 있는 것으로 나타났다. Spearman rank-order correlation으로 생물학적 반감기와 물리화학적 특성간의 상관계수를 산출하였을 때, 생물학적 반감기와 pKa는 R² = -0.928, p <0.01로 나타나, 생물학적 반감기는 pKa와 상관성이 있는 것으로 나타났다.

• 산업공학
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• 제24권4호
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• pp.314-322
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• 2011

This study analyzes a relationship between Data Envelopment Analysis(DEA) efficiency scores and a normalization index in order to examine the validity of DEA models. A normalization index concerned in this study is 'sales per R&D project fund' which is regarded as a crucial R&D project performance evaluation index in practice. For this correlation analysis, three distinct DEA models are selected such as DEA basic model, DEA/AR-I revised model(i.e. DEA basic model with Acceptance Region Type I constraints) and Super-Efficiency(SE) model. Especially, SE model is adopted where efficient R&D projects(i.e. Decision Making Units, DMU's) with DEA efficiency score of unity from DEA basic model can be further differentiated in ranks. Considering the non-normality and outliers, two rank correlation coefficients such as Spearman's ${\rho}_s$ and Kendall's ${\tau}_B$ are investigated in addition to Pearson's ${\gamma}$. With an up-to-date empirical massive dataset of n = 482 R&D projects associated with R&D Loan Program of Korea Information Communication Promotion Fund in the year of 2011, statistically significant (+) correlations are verified between the normalization index and every model's DEA efficiency scores with all three correlation coefficients. Especially, the congruence verified in this empirical analysis can be a useful reference for enhancing the practitioner's acceptability onto DEA efficiency scores as a real-world R&D project performance evaluation index.