• ETRI Journal
• /
• v.17 no.3
• /
• pp.45-63
• /
• 1995

This paper proposes an algorithm to improve the correlation between giga-hertz transverse electromagnetic (GTEM) cell and open area test site (OATS). It is based on the dipole modeling process of an unknown source object in a GTEM cell and on the evaluation of the approximate far field equations correlated with measured GTEM powers at output port of the GTEM cell. In this algorithm, the relative phase differences between dipole moments play an important part in modeling the test object as a set of dipoles and offer stable calculation of emission values. The radiated emission test using this algorithm requires fifteen orientations of equipment under test, but the increased orientations as compared with the previous method have little effect on the time needed for testing. Radiation from a notebook computer has been tested for statistical analysis of the correlation between GTEM data and OATS data. The emission test results of the notebook computer show that the mean, the standard deviation, and the correlation coefficient are -0.62, 1.99, and +0.85, respectively. These figures indicate that this algorithm provides improved accuracy in the measurement of electromagnetic emissions over the previous method.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.10
• /
• pp.54-62
• /
• 1994

The optical JTC system has the advantage of being applied to the real-time correlation system, but it has some difficulties that its amplitude and phase signals cannot be separately processed. Recently to solve those problems the BPEJTC and HPEJTC systemshaving the same characteristics of that of the POC and POF have been proposed. But there is no quantitive analysis how much the amplitude and phase signals are contributed to the correlation outputs respectively. In this paper, a new ACJTC system based on the conventional ACMF is proposed and discussed through the mathematical analysis. The good correlation discrimination of the proposed system is also analyzed by changing the relative contributions of the phase and amplitude signals for some similar targets. From the successful computer simulation results on the scenario where three same targets are periodically located on the natural backgrround, the possibility of the high performance real-time correlation system based on the optical ACJTC is suggested.

• Journal of Mechanical Science and Technology
• /
• v.16 no.5
• /
• pp.583-590
• /
• 2002

When a mechanical structure is driven by stationary wide band random point forces, the resulting vibration depends upon the number, location, and joint statistical properties of the exciting forces. In this study, under the assumption of light damping, an approximate procedure for analyzing plates is briefly outlined. The effects of number, location and correlation of the force field on the vibration level are then investigated for various cases in which random point forces with band limited white noise are applied, and the optimal spacing between input forces that produces a relative minimum in the vibration response is predicted.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1736-1740
• /
• 2003

There have been various studies to find out the correlation between subjective and objective evaluation ride comfort in vehicle. To be proper, subjective evaluation considers the signal pattern of vibration generated by vehicle. In this study, driving test is carried out to extract the correlation between subjective evaluation by subjects and vibration signals measured on the seat when a test vehicle is passing over test bumpers, which have two sorts of width change and height change respectively. A unique reference bumper is used to be compared with the relative comfort of test bumpers.

• International Journal of High-Rise Buildings
• /
• v.8 no.4
• /
• pp.313-324
• /
• 2019

This paper presents the analysis of wind speeds data measured on top of three neighboring high-rise buildings close to a beach in Xiamen city, China, during Typhoon "Usagi" 2013. Wind tunnel simulation was carried out to validate the field measurement results. Turbulence intensity, turbulence integral scale, power spectrum and cross correlation of recorded wind speed were studied in details. The low frequency trend component of the typhoon speed was also discussed. The field measurement results show turbulence intensity has strong dependence to the wind speed, upwind terrain and even the relative location to the Typhoon center. The low frequency fluctuation could severely affect the characteristics of wind. Cross correlation of the measured wind speeds on different buildings also showed some dependence on the upwind terrain roughness. After typhoon made landfall, the spatial correlation of wind speeds became weak with the coherence attenuating quickly in frequency domain.

• Journal of the Korean Society for Precision Engineering
• /
• v.11 no.1
• /
• pp.166-176
• /
• 1994

The problem of reducing the vibration level of elastic plates driven by multiple random point forces is analyzed in this study. First, the analytical solution for the vibration level of finite thin plates with four simply supported edges under the action of multiple random point force is derived. By assuming the plates to be lightly damped, an approximate solution for the vibration level of the plate is obtained. A numerical study is carried out to determine an optimal spacing distance between the multiple point forces in order to produce a relative minimum in the plate's vibration level. The optimal spacing distance is shown to depend on the given excitation band. The effects of wave cancellation in the near field of the multiple point forces are discussed by using the equivalence of certain stationary random responses and deterministic pulse responese.

• KIEAE Journal
• /
• v.12 no.6
• /
• pp.93-98
• /
• 2012

The concerns on high ozone concentration phenomenon is significantly growing in Seoul metropolitan area including the industry complex area, like Shiwha Banwol area. The aims of this research is the analysis of relationship between high concentrations of $O_3$ and solar radiation parameters in atmosphere. The understanding of the effects of solar radiation intensity, humidity, high air temperature on ozone concentration in a day is very useful to provide a direction for reducing of the high ozone concentration to a local government or a metropolitan government. The correlation analysis between maximum ozone concentration and various meteorological parameters in 2009 - 2011 carried out using IBM's SPSS program. The results showed that the mean correlations coefficient (R) between daily Ozone maximum and solar radiation resulted R = 0.64 during 2011. May - September in 10 air pollution stations. In case of correlations between daily ozone maximum and relative humidity showed negative correlation R = -0.61. The correlation analysis with mean air temperature during 1-3 PM resulted R = 0.29. This low correlation coefficient could be corrected by using of categorized data of ozone concentration. The daily maximum ozone concentration is more dependent on peak solar radiation and high air temperature during 1-3 PM than its simple daily maximum values. The results of this research would be used to develop the high ozone alert system around Seoul metropolitan area. This correlation analysis could be partially integrated to prediction of ozone peak concentration in connection with other methods like classification and regression tree(CART).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.05a
• /
• pp.704-706
• /
• 2022

In this study, we analyzed the correlation between the amount of photovoltaic power generation and the factors of meteorological changes. A total of 52,561 data were used in the correlation analysis from January 2018 to January 2020, and the variables used in the correlation analysis were time, horizontal plane scattering solar radiation, direct solar radiation, wind velocity, and relative humidity. The temperature was used. Based on this data, we used the Google Colab platform to analyze the correlation, and the analysis revealed whether there was a correlation between solar power and meteorological change factors.

• Korean Journal of Child Education & Care
• /
• v.19 no.1
• /
• pp.15-26
• /
• 2019

Objective: The purpose of the study was, first, to look for the correlation among child care teacher's job burnout, their empowerment, and their flourishing. The second aim was to find out the relative effects of job burnout and empowerment on the flourishing of child care teachers. Methods: The participants were 296 child care teachers from Seoul, Gyeonggi and Jeon-nam districts among whom questionnaires were distributed. Correlation and hierarchical regression analyses were used for the analysis with SPSS 21.0 program. Results: The results revealed that, first, while there was significant correlation in child care teacher's job burnout, their empowerment, and their flourishing. Child care teacher's job burnout showed a significant negative correlation with their empowerment and their flourishing, and child care teacher's empowerment had a significant positive correlation with their flourishing. Second, the relative influence on the flourish of child care teachers was in the order of empowerment and job burnout. In terms of sub-factors, the relative influence on the flourish of child care teachers was in the order of professionalism, autonomy, self-efficacy and job dissatisfaction. This study is meaningful in that it provided the basic data for improving the quality level of the child care. Conclusion/Implications: This study suggests that basic data for improving the quality of the child care. In order to improve the flourishing of child care teacher, it is necessary to find effective ways to eliminate the job burnout and increase the empowerment.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.6 no.1
• /
• pp.125-137
• /
• 1996

This study was designed to investigate effects of relative humidity on the breakthrough of charcoal tubes at a fixed vapor concentration and sampling time during mixed organic vapor sampling. A vapor generator was used to generate three different concentrations of mixed organic vapor and a stainless steel chamber was fabricated and utilized to maintain three different percentages of relative humidity while maintaining a constant temperature. The results were as follows; 1. At high relative humidity, breakthrough of mixed organic vapor occurred quickly at low vapor concentration than at high vapor concentration because of the reduced adsorption volume of charcoal tube due to humidity. 2. Breakthrough by competitive adsorption of vapors onto charcoal tube was observed at first from n-hexane having the lowest boiling point and highest vapor pressure among the three organic vapors investigated, followed by TCE. No breakthrough was observed from toluene under all experimental conditions. 3. For n-hexane, breakthrough was observed after 2 hours of sampling and breakthrough rates were increased as relative humidity increased. For TCE, breakthrough was found after 3 hours of sampling and breakthrough rates by sampling time were increased as vapor concentration increased. 4. The adsorbed amount of mixed organic vapor at breakthrough was shown to have statistically significant correlations with sampling time, relative humidity, and vapor concentration in descending order of correlation. Relative humidity and sampling time for n-hexane and sampling time and concentration for TCE were both statistically significantly correlated. 5. Relative humidity was found to affect the amount of breakthrough of mixed organic vapor and n-hexane. Among three percentages of relative humidity investigated, the amount of breakthrough at 85 % relative humidity was significantly larger than those of at lower percentages of relative humidity. No statistically significant difference was found between 25 % and 55 % relative humidity. 6. The results of multiple regression analysis between breakthrough and relative humidity, vapor concentrations showed that the coefficient of determination of mixed organic vapor was 0.263 and those of n-hexane and TCE were 0.275 and 0.189, respectively. 7. Flow rates of sampling pumps used were found to be affected by relative humidity present. At 25 %, 55 %, and 85 % relative humidity, the relative errors of sampling pump were 1.4 %, 13.4 %, and 18.6 %, respectively. In conclusion, the results of this study showed that high relative humidity could reduce the adsorption volume of charcoal tubes and subsequently increase breakthrough rates. Therefore, to prevent breakthrough when sampling mixed organic vapors, it is suggested that either sampling volume be reduced on the flow rate be lowered so as to minimize breakthrough of the most volatile organic vapor in the mixture. In addition, since the flow rates of a sampling pump can be adversely affected by high relative humidity, it is recommended to use a constant flow mode pump when sampling in the highly humid environment.