• Title/Summary/Keyword: Two-point correlation

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Relations of Near-Wall Streamwise Vortices to Wall Pressure Fluctuations in a Turbulent Boundary Layer (난류경계층내 주유동방향 와구조와 벽압력 변동간의 상관관계)

  • Seong, Hyeong-Jin;Kim, Jung-Nyeon;Choe, Jeong-Il
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.8
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    • pp.1068-1076
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    • 2001
  • The relations between wall pressure fluctuations and near-wall streamwise vortices are investigated in a spatially-developing turbulent boundary layer using the direct numerical simulation. The power spectra and two-point correlations of wall pressure fluctuations are presented to validate the present simulation. Emphasis is placed on the identification of the correlation between wall pressure fluctuations and streamwise vorticities. It is shown that wall pressure fluctuations are directly linked with the upstream streamwise vortices in the buffer region of the turbulent boundary layer. The maximum correlation occurs with the spanwise displacement from the location of wall pressure fluctuations. The conditionally-averaged vorticity field and the quadrant analysis of Reynolds shear stress indicate that the sweep events due to streamwise vortices generate positive wall pressure fluctuations, while negative wall pressure fluctuations are created beneath the ejection events and vortex cores. The instantaneous flow field and time records reveal that the rise of high wall pressure fluctuations coincide with the passages of the upstream streamwise vortices.

A Study on the Measurement of Heart Rate Variability using the Modified Laplacian Electrodes (수정된 라플라시안 센서를 이용한 심박변이도 측정에 관한 연구)

  • Lee, Chung-Keun;Shin, Hang-Sik;Kim, Hong-Rae;Lee, Jeong-Whan;Kim, Yong-Jun;Lee, Myoung-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.5
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    • pp.1050-1056
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    • 2009
  • Heart Rate Variability(HRV) is a parameter that represents monitoring variability of time intervals between R-peak in electrocardiography. HRV serves to various applications, such as indices of autonomic functions, prediction of cardiac sudden death, assessment of stress and emotional, etc. However, as measuring R-peak in ECG needs at least 3-electrodes, and it is inconvenient for end users. In this paper, we suggested the modified laplacian electrodes for measuring HRV at one-point, which are producted by MEMS fabrication and have the two circular electrodes on the pad. For optimal position and direction, we performed an experiment that compared with pearson correlation coefficient and the amplitude of signals, between standard lead II and proposed electrodes. We analyzed the HRV parameters, such as standard deviation of the NN interval(SDNN), high frequency(HF), low frequency(LF), LF/HF ratio. The result showed that the average correlation coefficient and amplitude are 0.967 and 0.685 mVpp at the position 2. The coeffiecient correlation between the standard HRV and proposed electrode-HRV is 0.999

A comparison of women's pattern between the Bunka and the Secoli (신문화식과 세꼴리식 여성복 원형 비교)

  • 최영림;김희은
    • Journal of the Korean Society of Clothing and Textiles
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    • v.27 no.11
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    • pp.1190-1197
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    • 2003
  • The purpose of this study is to compare and analyze methods of women's apparel prototypes and provide for some useful fundamental data to improve the apparel prototype suitable for Korean women. Two different drafting methods, the Bunka pattern of Japan Bunka Women's University and the Secoli pattern of Italy istituto carlo secoli, an italian pattern drafting institute, were selected. The result and discussion are as follows; In the calculation formula, the Bunka was shown more comfort at arm-hole part, because of it's lower arm-hole depth, wider arm-hole width and lower cap height in comparison with the Secoli. At the shoulder angle, the Bunka is inclined more in front shoulder than the back shoulder, whereas the Secoli is inclined more in back shoulder than the front shoulder. It could explain that the Bunka is suitable for bendforward type and the Secoli is suitable for lean-back type. In the sensory test, the one-piece pattern of the Secoli with 4cm ease was highly estimated in ease. It seems young women's preference to body conscious clothes which reflected in many new elastic fabrics. At the bust point to neck, the Bunka was highly estimated, compared with the Secoli. It seems like to be caused that for the bust point to neck formula, the Bunka used bust girth, the Secoli used stature which has low correlation with the bust point to neck.

A Study on Self-leadership, Fall Attitude, and Nurses' Behavior to Prevent Patient Falls (간호사의 셀프리더십과 낙상에 대한 태도 및 낙상예방행위에 관한 연구)

  • Choi, Ae Shin;Oh, Pok Ja
    • Journal of Korean Academy of Nursing Administration
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    • v.19 no.3
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    • pp.394-403
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    • 2013
  • Purpose: The purpose of this study was to identify self-leadership and attitude to patient falls and fall prevention behavior in nurses. Methods: The participants were 178 nurses from two general hospitals in Seoul. Data were collected from March 20 to May 10, 2012 using structured questionnaires which included a Self-leadership scale, Fall attitude scale, and Fall prevention scale. Data were analyzed using descriptive statistics, Pearson correlation and Hierarchial multiple regression with the SPSS/WIN 20.0 program. Results: The mean score for nurses' self-leadership was 3.48 (5 point scale). The average reported fall attitude was 3.59 (5 point scale) and fall prevention behavior was 3.26 (4 point scale). Self-leadership had a 18% explanatory power in fall attitude and a 5% explanatory power in fall prevention behavior. The factors which influenced fall prevention behavior were nurses' fall attitude (${\beta}$=.21, p=.009), fall prevention education (${\beta}$=.20, p=.007) and self-leadership (${\beta}$=.16, p=.047). All of the factors together had a 13.1% explanatory power. Conclusion: The results of this study suggest that provision of regularly fall prevention education to nurses is required and should include a program to activate their positive attitude and self-leadership in order to improve fall prevention behavior in nurses.

A COMPARATIVE STUDY ON THE POSTSURGICAL CHANGES BETWEEN ONE JAW SURGERY AND TWO-JAW SURGERY IN SKELETAL CLASS III PATIENTS (골격성 III급 부정교합자의 편악수술과 양악수술시 술후동태에 대한 비교연구)

  • Choi, Yang Sook;Son, Won-Sung
    • The korean journal of orthodontics
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    • v.27 no.2
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    • pp.297-313
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    • 1997
  • The purposes of this study were to compare the soft tissue changes following hard tissue change after surgery between the one jaw and two-jaw surgery in skeletal class III patients and to get the reference of the incisal inclination at presurgical orthodontics. For this study 24 patients for the two-jaw surgery group and 18 patients for one jaw surgery group were selected. Lateral cephalograms were taken at pretreatment, after presurgical orthodontic treatment, immediately after surgical treatment and at least 6 months after surgery. They were traced and analyzed on skeletodental structure and soft tissue. The results were as follows: 1. After surgery, maxilla, maxillary incisors and upper lip were moved anteriorly and superiorly in two-jaw surgery group. Mandible and mandibular incisors were moved posteriorly and superiorly, and thickness of lower lip was increased in both group but there were no statistically significant difference. Anterior facial height was more decreased in two-jaw surgery group (p<0.05). At least 6 months after surgery, by the postorthodontic treatment, maxillary incisors were moved labially 1.44mm, mandible and mandiibular incisors were moved lingually 1.43mrn, 1.26mm respectively in one jaw surgery group. But there was no statistically significant changes of hard tissue in two :jaw surgery group. 2. The correlation coefficients of maxillary hard and soft tissue horizontal changes were high in two jaw surgery group and the ratios for soft tissue to A point were 19% at Sri, 80% at SLS, 82% at LS. The ratios for soft tissue to B point were 92% at LI, 104% at ILS in one jaw surgery group, 89% at LI, 101% at ILS in two-jaw surgery group. 3. The correlation coefficients and change ratios of mandibular incisors and LL HS on lower lip horizontal changes were 0 0.89 and 75%, 85% in one jaw surgery group, 0.93, 0.90 and 76%, 87% in two-jaw surgery group. The correlation coefficients of maxillary incisors and Sn, SLS and LS on upper lip horizontal changes were 072, 0.76 and 0.75 in two jaw surgery group and ratios of changes were 57%, 58% and 59%. 4. The regression equations between skeletal horizontal discrepancy and incisal inclinaton were taken in one jaw surgery group. Those were FMIA=57.48-2.17ANB, U1-SN=-75.02+2.17SNB and $R^2$ were 0.63, 063 respectively. So if there is skeletal horizontal discrepancy by mandibular prognathism in one jaw surgery case, we consider attaining more labial inclination of maxillary incisors than normal and more lingual inclination of mandibular incisors than normal. But correlation coefficient of the regression equations in two jaw surgery group was low, so, that equation was not reliable.

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Comparative Analysis of the Correlation Between Local Meteorological Elements and the Concentration of Airborne Fungi in the Beopjusa and Seonamsa Temples

  • Kim, Myoung Nam;Lim, Bo A;Hong, Jin Young;Lee, Jeung Min;Park, Ji Hee;Jeong, So Young
    • Journal of Conservation Science
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    • v.34 no.4
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    • pp.283-293
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    • 2018
  • This study involved a comparative analysis of the correlation between meteorological elements and the concentration of airborne fungi(CFU) in relation to biological damage to two temples on piedmonts, which is a cultural heritage building. The work compared Beopjusa temple in Boeun(Chungcheongbuk-do Province) and Seonamsa temple in Suncheon(Jeollanam-do Province). Twelve meteorological elements and the CFU were measured and the Pearson correlation analysis was used to determine the degree of the relationship between them. The results showed that Beopjusa temple had high wind speed, high total horizontal radiation, high evaporation, and large number of days with precipitation. Seonamsa temple had high air temperature, high relative humidity, high dew point temperature, high sea level pressure, high precipitation, and high CFU. The CFU at Beopjusa temple did not have a linear correlation with meteorological elements, but at Seonamsa temple it was highly positive correlated with the number of days with precipitation, relative humidity, and precipitation, and was highly negative correlated with total horizontal radiation. In addition, Beopju and Seonamsa temple had a common linear relationship between factors not affected by the topographical conditions, and had a individual linear correlation between factors affected by the topographical conditions.

Comparison of the bovine blood gas parameters produced with three types of portable blood gas analyzers

  • Ro, Younghye;Choi, Woojae;Hong, Leegon;Kim, Eunkyung;Choe, Eunhui;Kim, Danil
    • Journal of Veterinary Science
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    • v.23 no.4
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    • pp.60.1-60.6
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    • 2022
  • Background: A definite diagnosis should be made in the bovine practice field, however, it was difficult to perform laboratory analysis immediately. Currently, three types of portable blood gas analyzers are available in Korea. Objectives: This study aimed to evaluate the correlations among these three analyzers. Methods: Seventy-two plasma samples from Holstein-Friesian cows were used for blood gas analysis, and three instruments (EDAN i15 Vet, VETSCAN i-STAT, and EPOC) were operated simultaneously. Moreover, plasma calcium levels were compared between these portable analyzers and blood chemistry device, which is usually used in a laboratory environment. Pearson analysis was performed to confirm the correlation of each parameter produced with the three instruments and blood chemistry analyzer. Results: As results, high correlation was observed in parameters of pH, pO2, potassium ion, ionized calcium, and glucose (p < 0.001, r > 0.7). In addition, pCO2 showed a moderate correlation among the three analyzers (p < 0.001, r > 0.5), and there was no correlation among all instruments for sodium ions. There was also a high correlation between ionized calcium from the three portable devices and total calcium from the biochemistry analyzer (p < 0.001, r > 0.9). Conclusions: In conclusion, there was a high correlation between results from the three different blood gas analyzers used in the bovine clinical field in Korea. Thus, a consistent diagnosis can be made even with different equipment if the operator is aware of the strengths and weaknesses of each piece of equipment and operates it properly.

A Study on the Correlation Lee Jae Ma's Four Types of Essential Physical Constitution and From index - Concerning Male and Female 3rd Year High School Student in Some Urban and Rural Areas - (사상체질류형(四象體質類型)과 체격(體格) 및 신체형태지수(身體形態指數)와의 비교연구(比較硏究) - 도시(都市)와 농촌(農村)의 일부지역(一部地域) 남녀고등학교(男女高等學校) 3학년(學年) 학생(學生)을 대상(對象)으로 -)

  • Lee, Moon-Ho;Hong, Sun-Yong
    • Journal of Sasang Constitutional Medicine
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    • v.2 no.1
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    • pp.71-85
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    • 1990
  • 673 third-year students of boy's and girl's high schools in Taegu city and Kuni-gun and Youngyang-gun and Euisung-gun in Kyongbuk province were selected and investigated as the subject, of this study on the correlation between Lee Jae Ma's Four Types of Essential Physical Constitution and Physical Form index. The result of the study was found as follows. First, as for Height, the findings were not identical with the expression that "person of shaoyin(minor Yin) Type are short and small -- while person of Taiyin (major Yin) Type are tall and big," cited in classification of four different constitutions in a document named "Dong-Eu-Su-Se-Bo-Won". Comparison of persons of Shaoyang (minor Yang) - Type proved infitness due to the lack of data on Height in documents concerning Lee Jae Ma's four types of essential physical constitution. Second, as for Sitting Height, the correlation was prored between the findings of this study and the expression in the above document describing external physical characteristics of shaoyin-Type persons that "The upper part and' the lower part of the body are well balanced", but in point of Relative Sitting Height, none between the two. Third, as for Chest-Girth and Relative Chest-Girth plus Weight and Relative Weight, the expression that "Persons of Taiyin(major Yin) Type have the largest physique of the lour types of persons in the characteristics of external physical features, and that they also tend to have continental(widechest or large-scaled) character and strong nerve, that they are stoutly-built and fal." proved to have the correlation with the findings of this study. Fourth, in point of Chest-Girth and Relative Chest-Girth, this study found that its findings have the correlation with the phrase that "Chests are well developed upwar -- and sturdy and solid." in describing the characteristics of Shaoyang (minor Yang)-Type person' external physical features, and that with the phrase that "Chests are narrow" in the case of Shaoyin(minor Yin)-Type persons. Fifth, as for Weight and Relative Weight, the correlation was found between the findings and the expression that "shaoyin-Type persons have comparatively less flesh" as a sign of external physical characteristics of Shaoyin-Type persons. The above-cited findings proved that there exist some correlations between external physique of the Lee Jae Ma's four types of essential constitution and physical Form Indexes. Actually, however, in clinical classification, it is desirable that this approach should be consulted only after carefull consideration based on Lee Jae Ma's theory, and it seems imperative to continue the study of objectivization of Lee's theory.

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A Fast Digital Elevation Model Extraction Algorithm Using Gradient Correlation (Gradient Correlation을 이용한 고속 수치지형표고 모델 추출 방법)

  • Chul Soo Ye;Byung Min Jeon;Kwae Hi Lee
    • Korean Journal of Remote Sensing
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    • v.14 no.3
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    • pp.250-261
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    • 1998
  • The purpose of this paper is to extract fast DEM (Digital Elevation Model) using satellite images. DEM extraction consists of three parts. First part is the modeling of satellite position and attitude, second part is the matching of two images to find corresponding points of them and third part is to calculate the elevation of each point by using the results of the first and second part. The position and attitude modeling of satellite is processed by using GCPs. A area based matching method is used to find corresponding points between the stereo satellite images. The elevation of each point is calculated using the exterior orientation parameters obtained from modeling and conjugate points from matching. In the DEM generation system, matching procedure holds most of a processing time, therefore to reduce the time for matching, a new fast matching algorithm using gradient correlation and fast similarity measure calculation method is proposed. In this paper, the SPOT satellite images, level 1A 6000$\times$6000 panchromatic images are used to extract DEM. The experiment result shows the possibility of fast DEM extraction with the satellite images.

On correlation and causality in the analysis of big data (빅 데이터 분석에서 상관성과 인과성)

  • Kim, Joonsung
    • Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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    • v.8 no.8
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    • pp.845-852
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    • 2018
  • Mayer-Schönberger and Cukier(2013) explain why big data is important for our life, while showing many cases in which analysis of big data has great significance for our life and raising intriguing issues on the analysis of big data. The two authors claim that correlation is in many ways practically far more efficient and versatile in the analysis of big data than causality. Moreover, they claim that causality could be abandoned since analysis and prediction founded on correlation must prevail. I critically examine the two authors' accounts of causality and correlation. First, I criticize that corelation is sufficient for our analysis of data and our prediction founded on the analysis. I point out their misunderstanding of the distinction between correlation and causality. I show that spurious correlation misleads our decision while analyzing Simpson paradox. Second, I criticize not only that causality is more inefficient in the analysis of big data than correlation, but also that there is no mathematical theory for causality. I introduce the mathematical theories of causality founded on structural equation theory, and show that causality has great significance for the analysis of big data.