• Title/Summary/Keyword: Time-frequency correlation

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A Study of Ionospheric Time Delay for Single-Frequency GPS Systems (단일 주파수 GPS 시스템에서의 전리층 전파지연 연구)

  • Park, Sung-Kyung
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.9
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    • pp.1-9
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    • 1994
  • Through the low orbit GPS satellite for a 3-dimensional real time position detechtion can be achieved anywhere. Utilizing the GPS sate llite detection values an analysis of the varing characteristics of the ionosphere can be achieved, and by calculating the correlation relationship of the position detection error and the ionospheric time delay characteristics, an advanced algorithm technique can be developed. Computer simulation of the developed algorithm for defining the corelation between the position detection error and the varing ionospheric time delay charcteristics has been proceeded. The results of simulation reveal the fact that the varing characteristics of the ionosphere nearly match the actual ionospheric time delay characteristics.

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Analysis and Research of 119 Silver Ambulance Activities and Its Development Methods (일부지역 119 노인전용구급차(Silver Ambulance)의 활동분석 및 발전방안)

  • Kwon, Hay-Rran
    • The Korean Journal of Emergency Medical Services
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    • v.11 no.3
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    • pp.191-204
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    • 2007
  • This study analyzes use and operation of silver ambulance with 110 patients who had used silver ambulance in Gwangju and Jeonnam regions from June of 2006 to June of 2007 and 53 paramedics who are involved directly in ambulance operation and the results of this analysis are as follows. 1. Users' health conditions, 69.1% of users answered as bad and 67.3% suffered from chronic diseases over 3 months and it was found that they used silver ambulance due to their bad health conditions. 2. Cronbach's alpha was 0.630 and family function index was generally reliable and solution was high as 1.60, but total points were low as 7.11 and it was considered that they had family troubles. 3. On the question of ambulance use, 44.5% answered they used it because it is free, 53.6% used it for appointed medical examination and treatment and 18.1% used it for emergency. 4. Degrees of satisfaction with ambulance and paramedics were 95.4% and 76.4% respectively and 80.0% of ambulance users answered ambulance arrived quickly within 15 min. 5. Correlation($x^2 $) between family or relative's residence and frequency of visits was 86.367 and its significance probability was 0.00 and it was found that it was significant in the level of 0.1%, but correlation($x^2 $) between visitors other than family or relatives and frequency of visits was 14.768 and its significance probability was 0.25 and it was found that it was not significant in the level of 5%. 6. Correlation($x^2 $) between transfer operation speed and mobilization time was found that it was not significant in the level of 5%. Correlation($x^2 $) between their own health condition purpose of ambulance use was 13.802 an 5.696 and its significance probability was 0.93 and it was found that it was not significant in the level of 1%, and it was considered because paramedics carried patients with safe operation.

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Text mining on internet-news regarding climate change and food (기후변화 및 식품 관련 뉴스기사의 텍스트 마이닝)

  • Hyun, Yoonjin;Kim, Jeong Seon;Jeong, Jin-Wook;Yun, Simon;Lee, Moon-Soo
    • Journal of the Korean Data and Information Science Society
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    • v.26 no.2
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    • pp.419-427
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    • 2015
  • Despite of correlation between climate changes and food-related information, it is still not easy for many users to get access to the information with interest. This study investigated how much climate change and food-related information are correlated with each other and how often they are exposed through frequency and correlation analysis on news articles on the internet portals. Through analysis on the frequency of climate change and food-related news articles, this study was able to figure out how often they are exposed at the same time by the internet news portals. In addition, a total of 59 correlation rules regarding the climate change and food-related vocabularies were derived from these news articles using the climate change and food-related glossaries. Then, a correlation between certain climate change-related and food-related words was analyzed in order to package the related words.

Improved Heat Transfer Coefficient in Heat Exchanger by the Use of Specialized Heating Surface (전열면의 특수표면화에 의한 열기기의 효율향상에 관하여)

  • Yim, Chang-Soon
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.8 no.3
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    • pp.131-150
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    • 1979
  • Recently only a few correlations between various factors due to the different grades of surface roughness for the nucleate pool boiling have been proposed. The main purpose of this work is to test the validity of these types of correlations between related factors to nucleate pool boiling phenomena. The boiling experiments using distilled water were carried out at the heat flux ranging from $7.4\times10^4\;to\;2.4\times10^5kcal/m^2h$ on the sintered porous metal surface with the cavity diameter of 10, n, 40, 70, $100{\mu}$, respectively, at the atmospheric pressure, To determine the bubble sizes, number of nucleation sites, delay and growth time, frequency of bubble emission and rising velocities of bubbles, the high speed motion picture technique was employed. In the correlation $f{\propto}D_b^n$, where f denotes frequency of bubble emission and $D_b$ departure diameter, n, the power factor of $D_b$, have been found to be from -2 to -10/3. The correlation C in the correlation between heat flux q and density of nucleation sites $\frac{N}{A}$, $q=C(\frac{N}{A})^n$, was appeared to be more crucial than the power factor n. The correlation of the heat flux q to the temperature difference ${\Delta}T$ and the density of nucleation sites$\frac{N}{A}$, was proposed to be $$q-460{\Delta}T^{\frac{5}{4}}=K{\Delta}T{\frac{5}{3}}(\frac{N}{A})^{\frac{2}{3}}$$. The values of heat transfer coefficient obtained in this experiments for the porous sintered metal surface appeared to be very high in comparison with the formerly obtained results for the other surfaces.

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Correlations among Internet Games Addiction, Self-esteem and Physical Health in Middle School Students (중학생의 인터넷게임중독, 자아존중감 및 신체건강간의 관계)

  • Joo, Ae-Ran
    • Research in Community and Public Health Nursing
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    • v.18 no.2
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    • pp.331-339
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    • 2007
  • Purpose: This study was conducted to identify correlations among internet games addiction (IGA), self-esteem and physical health in middle school students. Methods: A total of 428 middle school students were selected through simple random sampling. Data were collected from the $15^{th}$ to $30^{th}$ of March, 2006. Data were analyzed using SPSS/PC program by frequency, $\chi^2$-test, t-test, ANOVA, Duncan test, Pearson's correlation coefficient, and Stepwise Multiple Regression. Results: 1. According to the results of analyzing the degree of IGA, the addicted group was 1.9% 2. Analysis of IGA according to the general characteristics showed that there were statistically significant differences in on-line friend, using time and major leisure. 3. Analysis of physical health according to the general characteristics showed that there were statistically significant differences in on-line friend and off-line friend. 4. IGA was in a significantly negative correlation with self-esteem. 5. In the results of regression, using time was identified as a factor influencing the IGA. Conclusion: Considering the results above, we need to develop IGA prevention programs to enhance physical health and self-esteem and to control using time.

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Introduction to Chaos Analysis Method of Time Series Signal: With Priority Given to Oceanic Underwater Ambient Noise Signal (시계열 신호의 흔돈분석 기법 소개: 해양 수중소음 신호를 중심으로)

  • Choi, Bok-Kyoung;Kim, Bong-Chae;Shin, Chang-Woong
    • Ocean and Polar Research
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    • v.28 no.4
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    • pp.459-465
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    • 2006
  • Ambient noise as a background noise in the ocean has been well known for its the various and irregular signal characteristics. Generally, these signals we treated as noise and they are analyzed through stochastical level if they don't include definite sinusoidal signals. This study is to see how ocean ambient noise can be analyzed by the chaotic analysis technique. The chaotic analysis is carried out with underwater ambient noise obtained in areas near the Korean Peninsula. The calculated physical parameters of time series signal are as follows: histogram, self-correlation coefficient, delay time, frequency spectrum, sonogram, return map, embedding dimension, correlation dimension, Lyapunov exponent, etc. We investigate the chaotic pattern of noises from these parameters. From the embedding dimensions of underwater noises, the assesment of underwater noise by chaotic analysis shows similar results if they don't include a definite sinusoidal signal. However, the values of Lyapunov exponent (divergence exponent) are smaller than that of random noise signal. As a result we confirm the possibility of classification of underwater noise using Lyapunov analysis.

Real-Time Harmonic Parameters Analyzer for Evaluating Induction Motor Drive System (유도전동기 구동시스템 평가를 위한 실시간 고조피 파라미터 분석장치)

  • Lim, Young-Cheol;Jung, Young-Gook
    • Proceedings of the KIEE Conference
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    • 1997.11a
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    • pp.479-483
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    • 1997
  • In general, motor parameters can be divided into mechanical/electrical parameters and harmonic parameters. Mechanical/electrical parameters identification of motor have been studying systematically for a long time. But, systematical study on harmonic parameters analysis for efficient motor drive system are very poor. The goal of this paper is to propose analyzing method of harmonic parameters for motor drive system with various experimental graphic screens and numerical results and to develope harmonic parameters analyzer. A developed analyzer is made up 586-PC and DSP (digital signal processor) board, motor drive system, power and harmonic parameters analyzing software for windows. Harmonic parameters are analyzed using correlation signal processing techniques based on the correlation between voltage and current waveforms. Analysis results are visualized by 3-D current coordinates, and it is compared and evaluated with conventional time/frequency domain. To verify the validity of the proposed system, 1/4HP capacitor run type single phase induction motor and thyristor speed controller is used for analyzing. Harmonic parameters of motor drive system is analyzed and verified, with varying fire angle of thyristor speed controller, and the proposed approach is to confirm validity.

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Study on the Transfer Functions for Detecting Windings Displacement of Power Transformers with Impulse Method

  • Shon, Chae-Hwa;Yi, Sang-Hwa;Lee, Heun-Jin;Kang, Dong-Sik
    • Journal of Electrical Engineering and Technology
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    • v.7 no.6
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    • pp.876-883
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    • 2012
  • The paper investigates three types of transfer function methods for detecting displacements of winding in a model transformer. To acquire these transfer functions, the measuring method of input voltage, current and its response is used in impulse method. The applied impulse voltages had three rising times, which were short rising time (less than 0.6 ${\mu}s$), medium rising time (about 0.8 ${\mu}s$) and long rising time (about 1 ${\mu}s$) in front waves. Every 10 measurements of voltage and current waves were averaged from 50 measurements of voltage and current waves. These transfer functions were tested in normal, 24mm elevated and 48mm elevated windings conditions and were analyzed with correlation coefficients and spectrum deviations. In the analysis, the results depend on the types of transfer functions and the rising times of input voltages.

Self-care and Physical Symptom by Gender in Korean Type2 Diabetic Patients (제2형 당뇨병 환자의 성별 자가관리와 자각증상 차이)

  • Kim, Hee-Seung;Park, Chai-Soon
    • Women's Health Nursing
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    • v.9 no.3
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    • pp.270-276
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    • 2003
  • Purpose: The purpose of this study was to investigate the self-care and the physical symptom and to analyse the correlation between self-care and physical symptom in type2 diabetic patients. Method: 201 Participants were recruited from the endocrinology outpatient department of a tertiary care hospital in an urban city. The data were collected by self report self-care and physical symptom questionnaire. Results: The alcohol drinking frequency was lower in female than in male patients. The frequency of nausea or vomiting, morning headaches, lightheadedness, weakness, pain in the heart, pain in the back, stiffness in any join or muscle, and getting very tired in a short time were higher in female than in male diabetic patients. The exercise frequency was negatively correlated with physical symptom in female patients. Conclusion: The alcohol drinking frequency was lower in female than in male patients. The female patients had more physical symptoms than the male patients. The exercise frequency was negatively correlated with physical symptom in female patients.

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Analysis of Natural Frequency According to Span of Foot-bridges (보도교의 구조시스템별 고유진동수 분석)

  • Do, Ki Young;Yoon, Sung Won
    • Journal of Korean Society of Steel Construction
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    • v.26 no.5
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    • pp.375-383
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    • 2014
  • In Seoul, total 166 places of foot-bridges were constructed but a study on correlation between resonance occurrence status by gait vibration and natural frequency by each span and that between span based on structural system and natural frequency is very unsatisfactory in reality. Consequently in this study, time series wave form, power spectrum and natural frequency were analyzed based on resonance occurrence by targeting 65 places of foot-bridges being constructed in Seoul through convenient and simple portable vibration meter.