• 제목/요약/키워드: Time-frequency correlation

검색결과 875건 처리시간 0.023초

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

  • Park, Sung-Kyung
    • 전자공학회논문지A
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    • 제31A권9호
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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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일부지역 119 노인전용구급차(Silver Ambulance)의 활동분석 및 발전방안 (Analysis and Research of 119 Silver Ambulance Activities and Its Development Methods)

  • 권혜란
    • 한국응급구조학회지
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    • 제11권3호
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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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기후변화 및 식품 관련 뉴스기사의 텍스트 마이닝 (Text mining on internet-news regarding climate change and food)

  • 현윤진;김정선;정진욱;윤시몬;이문수
    • Journal of the Korean Data and Information Science Society
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    • 제26권2호
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    • pp.419-427
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    • 2015
  • 기후변화와 식품 관련 정보가 유기적인 관련이 있음에도 불구하고, 사실상 현실에서는 사용자들이 직접 그 관련성에 대한 관심을 가지고, 해당 정보에 대한 접근이 용이하다고 말하기는 어렵다.본 연구는 실제 사용자들이 직접적으로 노출되는 인터넷 포털 사이트의 뉴스 기사에 대한 빈도분석 및 연관관계 분석을 통해 기후변화 및 식품 관련 정보가 어느 정도의 연관성을 가지고 얼마나 자주 나타나고 있는지에 대해 파악하였다. 또한 추출된 기후변화 및 식품 관련 뉴스를 대상으로 기후변화 용어 사전과 식품 관련 용어 사전을 활용하여 기후변화 관련 용어와 식품 관련 용어의 총 59개의 연관관계 규칙을 도출함으로써, 특정 기후변화 관련 용어가 어떠한 식품 관련 용어와 연관관계를 갖는지 파악하여, 추후 두 용어를 패키징해 제공할 수 있는 발판을 마련하였다.

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

  • 임장순
    • 대한설비공학회지:설비저널
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    • 제8권3호
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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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중학생의 인터넷게임중독, 자아존중감 및 신체건강간의 관계 (Correlations among Internet Games Addiction, Self-esteem and Physical Health in Middle School Students)

  • 주애란
    • 지역사회간호학회지
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    • 제18권2호
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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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시계열 신호의 흔돈분석 기법 소개: 해양 수중소음 신호를 중심으로 (Introduction to Chaos Analysis Method of Time Series Signal: With Priority Given to Oceanic Underwater Ambient Noise Signal)

  • 최복경;김봉채;신창웅
    • Ocean and Polar Research
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    • 제28권4호
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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.

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

  • 임영철;정영국
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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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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    • 제7권6호
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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.

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

  • 김희승;박재순
    • 여성건강간호학회지
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    • 제9권3호
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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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보도교의 구조시스템별 고유진동수 분석 (Analysis of Natural Frequency According to Span of Foot-bridges)

  • 도기영;윤성원
    • 한국강구조학회 논문집
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    • 제26권5호
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    • pp.375-383
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    • 2014
  • 최근 자전거나 보행자들이 쉽고 편리하게 이동 할 수 있는 보도교와 미관중심의 보도교가 가설되고 있다. 그러나 보행자의 보행이 보도교의 고유진동수와 근접할 경우 공진현상에 의해 큰 진폭이 발생하여 보행자에게 보행시 불안감을 조성시킨다. 그러나 보행시 진동에 따른 연구는 매우 미약하다. 따라서 휴대용 진동계측기를 통하여 서울시에 가설된 65개소의 보도교를 대상으로 공진발생에 따른 고유진동수를 분석하였고 경간별 고유진동수 상관관계와 구조시스템에 따른 경간과 고유진동수의 상관관계를 분석하였다.