• 제목/요약/키워드: Spearman rank-order correlation coefficient

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바이오디젤 혼합연료의 배기특성 실험결과에 대한 통계학적 해석 (Statistical Analysis of Experimental Results on Emission Characteristics of Biodiesel Blended Fuel)

  • 염정국;윤정환
    • 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.

The Study of Emission Characteristics of Biodiesel Fuel in Diesel Engines

  • Yeom, Jeong-Kuk
    • 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 $p_{inj}=600bar$.

디젤엔진에서 바이오디젤의 배기가스 특성 평가 (Estimation of the Exhaust Characteristics of Biodiesel Used in Diesel Engine)

  • 백석흠;윤정환;정우성;하형수;정성식;염정국
    • 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.

공공도서관 사서의 평생교육업무에 대한 인식 연구 - 인천지역을 중심으로 - (An Analysis on the Perception of Public Librarians about Lifelong Education Tasks: Focus on Incheon Metropolitan City)

  • 김남지;조재인
    • 한국비블리아학회지
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    • 제27권3호
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    • pp.51-73
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    • 2016
  • 본 연구는 공공도서관 사서들이 어려움을 느끼고 있는 평생교육 단위직무를 파악하고 동시에 재교육이 필요한 교육 내용에 대한 우선 순위를 맨휘트니(Mann Whitney U-test), 다중회귀분석(Multiple regression analysis)과 AHP(Analytic Hierarchy Process) 분석을 통해 제시하였다. 첫번째, 조사 대상 사서의 87%가 평생교육 직무는 보통이거나 어렵다고 인식하고 있었으며, 단위 업무별로는 운영계획수립을 가장 어려운 직무로 생각하고 있었다. 두번째, 평생교육사 자격이 있는 사서가 없는 경우에 비해 업무를 수월하게 인식하고 있었으며(P=0.04), 단위업무별로는 강사섭외(P=0.04), 운영계획수립(P=0.05)에 있어 유의한 차이가 검증되었다. 또한 평생교육관련 경력이 길수록 업무를 수월하게 (R=-0.217) 느끼는 것으로 나타났으며, 특히, 일정편성(R=-0.33), 진행업무(R=-0.22)에 있어, 통계적으로 유의한 상관성을 보였다. 세번째, 다중회귀분석 결과, 공공도서관 사서들이 평생교육업무 전반에 대하여 느끼는 체감 난이도에 유의한 영향을 주는 단위 직무는 운영계획수립(P=0.04)과 홍보(P=0.05) 업무인 것으로 나타났으며, 그중 운영계획수립(${\beta}=0.233$)이 체감 난이도 형성에 가장 많은 영향을 주는 요인인 것으로 판명되었다. 한편, 91%의 사서가 평생교육 직무 관련 재교육이 필요하다고 느끼고 있으며, 스피어만(Spearman rank-order correlation coefficient) 분석 결과(R=-0.210), 평생교육 업무에 대한 체감 난이도가 높은 사서일수록 재교육 필요성을 더욱 많이 느끼고 있는 것으로 나타났다. AHP 분석 결과 평생교육 직무 관련 재교육 내용은 이용자와의 소통(CU P=0.310), 기획(PL P=0.246), 마케팅(LM P=0.173) 순의 가중치를 보였으며, 도출된 CR(Consistency Ratio) 비율은 0.146으로 계산돼, 응답에 대한 일관성은 허용할 수 있는 수준인 것으로 나타났다.

Active Days around Solar Minimum and Solar Cycle Parameter

  • Chang, Heon-Young
    • Journal of Astronomy and Space Sciences
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    • 제38권1호
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    • pp.23-29
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    • 2021
  • Utilizing a new version of the sunspot number and group sunspot number dataset available since 2015, we have statistically studied the relationship between solar activity parameters describing solar cycles and the slope of the linear relationship between the monthly sunspot numbers and the monthly number of active days in percentage (AD). As an effort of evaluating possibilities in use of the number of active days to predict solar activity, it is worthwhile to revisit and extend the analysis performed earlier. In calculating the Pearson's linear correlation coefficient r, the Spearman's rank-order correlation coefficient rs, and the Kendall's τ coefficient with the rejection probability, we have calculated the slope for a given solar cycle in three different ways, namely, by counting the spotless day that occurred during the ascending phase and the descending phase of the solar cycle separately, and during the period corresponding to solar minimum ± 2 years as well. We have found that the maximum solar sunspot number of a given solar cycle and the duration of the ascending phase are hardly correlated with the slope of a linear function of the monthly sunspot numbers and AD. On the other hand, the duration of a solar cycle is found to be marginally correlated with the slope with the rejection probabilities less than a couple of percent. We have also attempted to compare the relation of the monthly sunspot numbers with AD for the even and odd solar cycles. It is inconclusive, however, that the slopes of the linear relationship between the monthly group numbers and AD are subject to the even and odd solar cycles.

한.미 대학도서관의 구성요소와 직원규모와의 관계에 관한 비교 연구 (A comparative study on correlations between the related factors and the staff size of university libraries in Korea and United States of America)

  • 손정표
    • 한국도서관정보학회지
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    • 제24권
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    • pp.1-44
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    • 1996
  • This study is to analyze correlations between 10 factors related to university libraries and the number of professional staff, nonprofessional staff, and total library staff of university libraries in Korea and United States of America. The results of this study are summarized as follows: 1. In the case of Korea, there are high positive correlations between the number of total library staff and 7 of 10 variables (coefficient : 0.76-0.99) ; between the number of professional staff and 7 of 10 variables, same as the above (coefficient : 0.76-0.99) ; between the number of nonprofessional staff and 4 of 10 variables (coefficient 0.73-0.93). In the case of America, there are high positive correlations between the number of total library staff and 6 of 10 variables (coefficient : 0.74-0.97) ; between the number of professional staff and 5 of 10 variables (coefficient : 0.78-0.87): between the number of nonprofessional staff and 6 of 10 variables (coefficient : 0.73-0., 96). 2. All the. rank orders of correlation coefficients of two countries show little significant difference, by the results of the Spearman's Rank Order Correlation analysis (coefficient : total staff, 0.9152: professional staff, 0.8667 ; nonprofessional staff, 0.9030) 3. In the case of Korea, among the above factors, correlations of the total university expenditure and the library expenditure show a significant difference more than ones of the other factors. On the other hand, in the case of American professional staff, the correlations of the library expenditure, the library materials expenditure and the volumes in library show a significant difference more than ones of the other factors, while in the case of American nonprofessional staff, only the library expenditure shows a significant difference more than the others. 4. In the results of the correlation analysis between the professional staff and nonprofessional staff in Korea, the number of graduate enrollments, volumes in library, library expenditure and total university expenditure show higher positive correlation to the professional staff than the nonprofessional staff. However, in the case of America, the library expenditure and the library materials expenditure show higher positive correlation to the nonprofessional staff than the professional staff, while the university expenditure per student shows higher positive correlation to the professional staff. 5. In the results of the correlation analysis between Korea and America, in the case of the total library staff, the undergraduate enrollments, the total university expenditure and the library expenditure show higher positive correlation to Korea than America, and in the case of the professional staff, the graduate, enrollments, the volumes in library and the above 3 factors also show higher positive correlation to Korea than America. But in the case of the nonprofessional staff, the graduate enrollments, the volumes in library and library materials expenditure show higher correlation to America than Korea, while the total university expenditure shows the o n.0, pposit phenomenon of the above. And the other factors by the type of staff are little significant difference between two countries.

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들깻잎에서 Triazole계 살균제의 생물학적 반감기와 물리화학적 특성과의 상관관계 (Correlation between physicochemical properties and biological half-life of triazole fungicides in perilla leaf)

  • 이상협;곽세연;황정인;김효정;김태화;김장억
    • 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.

Maximum Sunspot Numbers and Active Days

  • Chang, Heon-Young
    • Journal of Astronomy and Space Sciences
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    • 제30권3호
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    • pp.163-168
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    • 2013
  • Parameters associated with solar minimum have been studied to relate them to solar activity at solar maximum so that one could possibly predict behaviors of an upcoming solar cycle. The number of active days has been known as a reliable indicator of solar activity around solar minimum. Active days are days with sunspots reported on the solar disk. In this work, we have explored the relationship between the sunspot numbers at solar maximum and the characteristics of the monthly number of active days. Specifically, we have statistically examined how the maximum monthly sunspot number of a given solar cycle is correlated with the slope of the linear relationship between monthly sunspot numbers and the monthly number of active days for the corresponding solar cycle. We have calculated the linear correlation coefficient r and the Spearman rank-order correlation coefficient $r_s$ for data sets prepared under various conditions. Even though marginal correlations are found, they turn out to be insufficiently significant (r ~ 0.3). Nonetheless, we have confirmed that the slope of the linear relationship between monthly sunspot numbers and the monthly number of active days is less steep when solar cycles belonging to the "Modern Maximum" are considered compared with rests of solar cycles. We conclude, therefore, that the slope of the linear relationship between monthly sunspot numbers and the monthly number of active days is indeed dependent on the solar activity at its maxima, but that this simple relationship should be insufficient as a valid method to predict the following solar activity amplitude.

The Relationship between Functional Movement Screen and Ankle Dysfunctions with Chronic Ankle Instability

  • Choi, Ho-Suk;Shin, Won-Seob;Shim, Jae-Kwang;Choi, Sung-Jin;Bang, Dae-Hyouk
    • The Journal of Korean Physical Therapy
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    • 제26권6호
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    • pp.459-463
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    • 2014
  • Purpose: The purpose of this study was to investigate the correlations between functional movement screen (FMS) and ankle dysfunctions in subjects with chronic ankle instability (CAI). Methods: This study was a cross-sectional study of 20 participants with CAI. The ankle dorsiflexion range of motion (ROM), Foot and Ankle Disability Index (FADI), center of pressure (COP) path length, and COP velocity for ankle dysfunction were measured in all the subjects. All the subjects underwent the FMS concerned with ankle functions consisted of deep squats, hurdle steps and in-line lunges. The Spearman rank-order correlation coefficient was used to determine relationship between the ankle ROM, FADI, COP and FMS. Results: The results of the deep squat and in-line lunge exercises revealed a significant correlation with the ankle dorsiflexion ROM, FADI, COP path length, and COP velocity. The hurdle step showed no correlation with the ankle dorsiflexion ROM and FADI but a significant relationship with the COP path length and COP velocity. Conclusion: The results of this study showed that relationship deep squat and in-line lunge and it is suggested that an assessment tool using ankle dorsiflexion ROM and ankle instability would be clinically effective.

여자대학생의 BMI와 신체상평정척도(CDRS) 분류기준에 대한 일치도 검정 (The Measures of Agreement between the Classification Standard of BMI and that of CDRS in Women university students)

  • 남덕현
    • 디지털융복합연구
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    • 제14권2호
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    • pp.519-527
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    • 2016
  • 이 연구는 BMI 분류기준과 9점-신체상평정척도 분류기준의 일치도를 조사하여 현장적용의 유용성을 확인하고, 여대생들이 체형에 대해 실제로 인식하고 정도를 파악하여 체형인식의 왜곡에 대한 올바른 정보와 비만의 기준에 대한 정보 제공에 목적이 있다. BMI 분류기준과 신체상평정척도 분류기준의 일치도, 그리고 여대생의 BMI에 따른 신체상 인식 정도를 알아보기 위하여 교차분석, Spearman의 등위차상관계수 및 카파통계량을 산출하였다. 분석결과 일반 여자대학생이 판정한 신체상 평정척도 분류기준과 BMI 분류기준은 통계적으로 ${\rho}=.719$(p<.001)로 높은 상관과 ${\kappa}=.506$(p<.001)로 보통 수준의 일치도를 나타냈다. 이러한 결과를 바탕으로 차후 신체상과 관련하여 인종의 특성에 따른 크기와 형태를 조정할 필요가 있으며 인구통계학적 특성이 다르거나 비만도가 높은 대상자를 선별하여 그들의 체형인식과 심리적인 측면에 관한 추가적인 연구가 필요하다.