• Title/Summary/Keyword: cross correlation functions

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Flux Monitoring of Intraday Variable Source with the KVN Ulsan Radio Telescope

  • Lee, Jee-Won;Sohn, Bong-Won;Byun, Do-Young;Kim, Sug-Soo S.
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.60.2-60.2
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    • 2011
  • We introduce the preliminary results of flux monitoring of BL Lac object 0716+714 with the KVN Ulsan 21m radio telescope. This radio source is well known as the intraday variable (IDV) source which is characterized by the rapid flux variation on the time scale of a day or less. In general, the IDV phenomenon is interpreted as the effect of refractive scintillation in the interstellar medium or the evidence of intrinsic flux variation. In previous observations that took a few days, however, it had not been detected the flux variation of short time scale but the monotonic increase and decrease. Therefore, to investigate the longer time scale of 0716+714, we had the flux variation monitoring at 22GHz and 43GHz simultaneously for 9 months from October 2010 to June 2011. We present here the structure functions and the cross correlation functions between different frequencies as well as the light curves.

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Validity of the Self-efficacy for Interprofessional Experimental Learning Scale in Korea (한국판 전문직 간 학습에 대한 자기 효능감 척도의 타당화)

  • Kwon, Oh Young;Park, Kyung Hye;Park, Kwi Hwa;Kang, Youngjoon
    • Korean Medical Education Review
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    • v.21 no.3
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    • pp.155-161
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    • 2019
  • Interprofessional education (IPE) can promote high-quality patient care and good medical outcomes through teamwork among health professionals. However, there are no valid measurements to prove the effectiveness of IPE in Korea. This study aimed to develop and test a Korean version of the Self-efficacy for Interprofessional Experimental Learning Scale (SEIEL). The original SEIEL was translated into Korean by two experienced medical professors, and 368 questionnaires were collected from medical and nursing students (third and fourth year). To analyze the validity of the Korean version of the SEIEL, an exploratory and confirmatory factor analysis was conducted. Cronbach's ${\alpha}$ was used to evaluate reliability. Results from the exploratory factor analysis identified two functions: "interprofessional collaboration" and "interprofessional team evaluation." A significant cross-correlation was found between the two functions (r=0.690, p<0.001), with a Cronbach's ${\alpha}$ value of 0.932. The reliability and validity of the Korean version of the SEIEL was identified in this study. This tool can be helpful in measuring the effectiveness of IPE in Korea.

Correlation and Hysteresis Analysis between Air and Water Temperatures in the Coastal Zone - Masan Bay (연안해역 기온과 수온의 상관관계 및 이력현상 분석)

  • Cho, Hong-Yeon;Lee, Khil-Ha;Cho, Kyung-Jun;Kim, Jun-Sung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.3
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    • pp.213-221
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    • 2007
  • In response to anthropogenic global warming due to a buildup greenhouse gas, the effect of the air temperature on water temperature has been noticed and some efforts have been made to build an air/water temperature relationship at the Masan Bay area by the Ministry of Maritime Affairs & Fisheries (MOMAF). As a result of analyzing the auto- and cross-correlation coefficient between air/water temperature, high correlation $(\sim0.9)$ is shown and the correlation coefficient of air temperature is higher than that of water temperature at the lag time less than approximately 10 days. Separate functions are fitted to the air/water relationship at the Masan Bay to take hysteresis into account. The slopes of the straight line for the rising limb are 0.829 and 0.774 for MA1 and MA2 station respectively, while 1.385 and 1.444 ($\sim1.75$ times larger) for the falling limb. Consequently, the seasonal hysteresis should be considered in order to determine an air/water relationship and accurately estimate the water temperature using the air temperature at Masan Bay.

Cluster analysis for highway speed according to patterns and effects (고속도로 구간별 통행속도의 패턴과 영향에 따른 군집분석)

  • Kim, Byungsoo;An, Soyoung;Son, Jungmin;Park, Hyemi
    • The Korean Journal of Applied Statistics
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    • v.29 no.5
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    • pp.949-960
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    • 2016
  • This paper uses all sections of highway data (VDS) for two years (Jan. 2014-Dec. 2015), with 15 minute units. The first purpose of this study is to find clusters with similar patterns that appear repeatedly with time variables of month, week and hour. The cluster analysis results indicate a variety of patterns of average traffic speeds by time variables depending on the clusters; subsequently, these can be utilized to model for the forecast of the speed at a specific time. The second purpose is to do cluster analysis for grouping sections by effect nets that are closely related to each other. For the similarity measure we use cross-correlation functions calculated after pre-whitening the speed of each section. The cluster analysis gets 19 clusters, and sections within a cluster are geographically close. These results are expected to help to forecast a real-time speed.

Deep learning-based approach to improve the accuracy of time difference of arrival - based sound source localization (도달시간차 기반의 음원 위치 추정법의 정확도 향상을 위한 딥러닝 적용 연구)

  • Iljoo Jeong;Hyunsuk Huh;In-Jee Jung;Seungchul Lee
    • The Journal of the Acoustical Society of Korea
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    • v.43 no.2
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    • pp.178-183
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    • 2024
  • This study introduces an enhanced sound source localization technique, bolstered by a data-driven deep learning approach, to improve the precision and accuracy of direction of arrival estimation. Focused on refining Time Difference Of Arrival (TDOA) based sound source localization, the research hinges on accurately estimating TDOA from cross-correlation functions. Accurately estimating the TDOA still remains a limitation in this research field because the measured value from actual microphones are mixed with a lot of noise. Additionally, the digitization process of acoustic signals introduces quantization errors, associated with the sampling frequency of the measurement system, that limit the precision of TDOA estimation. A deep learning-based approach is designed to overcome these limitations in TDOA accuracy and precision. To validate the method, we conduct comprehensive evaluations using both two and three-microphone array configurations. Moreover, the feasibility and real-world applicability of the suggested method are further substantiated through experiments conducted in an anechoic chamber.

An Analysis of Factors Influencing Job Satisfaction among Nurses Working in College Health Centers (대학보건소 간호사의 직무만족 영향요인 분석)

  • Cha, Kyu Jung;Song, Mi Ryeong
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.20 no.3
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    • pp.259-268
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    • 2013
  • Purpose: The purpose of this study was to identify factors influencing job satisfaction among nurses working in college health centers in order to enhance their role functions and to increase their work capabilities. Method: In this study a cross-sectional survey was used to collect data from 106 nurses working in college health centers. Collected data were analyzed using frequency, Pearson correlation coefficients, independent t-test, one-way ANOVA and multiple regression with the SPSS 20.0. Results: Mean scores for self-efficacy, job stress and job satisfaction for the participants were 3.86 (5-point scale), 2.51 (5-point scale) and 3.37 (5-point scale) respectively. There was a negative correlation between self-efficacy and job satisfaction (r=-.653, p<.001). Factors influencing job satisfaction were job stress (${\beta}$=-.58, p=<.001), level of perception among the nurses that they were contributing to the health promotion of students (${\beta}$=-.21, p=.005) and marital status (${\beta}$=.17, p=.029). These 3 elements accounted for 47.7% of the variance in job satisfaction. Conclusions: The results indicate that reduction in job stress and increase in the perception that nurses are contributing to the promotion of students' health are important to reinforce the role function of nurses and to increase their work capabilities.

Output only structural modal identification using matrix pencil method

  • Nagarajaiah, Satish;Chen, Bilei
    • Structural Monitoring and Maintenance
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    • v.3 no.4
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    • pp.395-406
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    • 2016
  • Modal parameter identification has received much attention recently for their usefulness in earthquake engineering, damage detection and structural health monitoring. The identification method based on Matrix Pencil technique is adopted in this paper to identify structural modal parameters, such as natural frequencies, damping ratios and modal shapes using impulse vibration responses. This method can also be applied to dynamic responses induced by stationary and white-noise inputs since the auto- and cross-correlation function of the two outputs has the same form as the impulse response dynamic functions. Matrix Pencil method is very robust to noise contained in the measurement data. It has a lower variance of estimates of the parameters of interest than the Polynomial Method, and is also computationally more efficient. The numerical simulation results show that this technique can identify modal parameters accurately even if the noise level is high.

Analysis of Cochlear Characteristics Using Evoked Otoacoustic Emission (유발이음향 방사현상을 이용한 와우각 특성 해석)

  • Lee, Nam-Ho;Choi, Jin-Young;Cho, Jin-Ho;Lee, Kuhn-Il
    • Proceedings of the KOSOMBE Conference
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    • v.1992 no.05
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    • pp.133-138
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    • 1992
  • Evoked otoacoustic emission (e-OAE) signals are measured from adult and analyzed by computer. Stimulation and detection are repeated and averaged 1000 times for noise cancellation. e-OAE signals are analyzed on frequency domain and time domain. The frequency domain analysis reveals that frequency of stimulus and emission has lineal relationship in 50 dB input sound amplitude. This result altos the cross correlation method to be applied for latency calculation. As the stimulus frequency grows higher, the latency tine is shorter and the gain or emission signal becomes greater. We introduced two mathmatical functions to identify these latecy and gain. These results can be utilized for cochlear modeling.

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Characteristic of Frost Growth on a Cold Cylinder Surface in Cross Flow (직교류 내 원관 표면에서의 서리층 성장 특성)

  • Yang Dong-Keun;Kim Min-Soo;Lee Kwan-Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.2
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    • pp.122-128
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    • 2006
  • In this paper, frosting experiments were conducted with variations of frosting parameters in order to obtain the correlations of frost properties. As a result, the local thickness, density, and surface temperature of the frost layer were presented. The dimensionless correlations for the frost thickness, frost density, frost surface temperature and heat transfer coefficient were derived as functions of dimensionless frosting parameters by using a dimensional analysis.

Preliminary Study on Joint Inversion of Geophysical Data (물리탐사자료 복합역산을 위한 예비연구)

  • Kim, Jung-Ho
    • 한국지구물리탐사학회:학술대회논문집
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    • 2007.06a
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    • pp.54-57
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    • 2007
  • Recently, multidimensional joint inversion of geophysical data based on fundamentally different physical properties has been actively studied. Joint inversion can provide a way to much more accurately image the subsurface structure. Through the joint inversion, furthermore, it is possible to directly estimate non-geophysical material properties from geophysical measurements. In this study, I derive the objective functions and normal equations of three different joint inversion approaches: one approach based on the structural similarity using cross-gradient, and the other two using the a priori information on the model parameters and the correlation between material properties. Since all the equations derived in this study are based on the same inversion method (smoothness constrained least-squares), it is possible to mix the joint inversion methods so as to produce a new joint inversion algorithm.

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