• 전기의세계
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• v.28 no.4
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• pp.47-52
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• 1979

Total number of resonant modes in a microwave oven cavity may be maximized for a given frequency bandwidth to obtain more uniform power distribution by choosing proper size of the cavity. The total number of modes is calculated for a dielectrically loaded rectangular cavity and its size is suggested here for which the change in the number of modes is less sensitive to the change of dielectric layer thickness and its total number of modes is maximized in a given range of cavity sizes. A prove coupled rectangular cavity is constructed and the total existing modes are measured to see the change of modes depending on the dielectric layer thickness and the cavity size. Surface wave mode existing in the dielectric layer is confirmed by measuring Q and the input impedance of the cavity for this mode, which closely compares with the calculation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.7
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• pp.924-929
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• 2000

This paper addresses a new technique of measuring the mean flow velocity over the cross sectional area of the pipe using sound field reconstruction. When fluid flows in the pipe and two plane waves propagate oppositely through the medium, the flow velocity causes the change of wave number of the plane waves. The wave number of the positive going plane wave decreases and that of negative going one increases in comparison to static medium in the pipe. Theoretical backgrounds of this method are introduced in detail and the measurement of mean flow velocity using the sound field reconstruction is not affected by velocity profile upstream of microphones.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.444-450
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• 2024

Based on multiple measurements of ionization loss, the Time Projection Chamber (TPC) combines strong tracking ability with particle identification ability in a large momentum range, which is an important advantage of TPC detection technology over traditional ionization measurement technology. According to these two characteristics of TPC, applying it to the measurement of fission cross-section can greatly improve the measurement accuracy. During the measurement of the fission cross-section, the number of target nuclei is required to be accurately measured. So this paper introduces a method for measuring the number of ²³⁵U target nuclei using a fission TPC system. The measurement result agrees with the reference value, and relative error is around 1 %.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.185-192
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• 2011

Pearson's correlation was used to determine relations between infiltration and affecting factors using flow monitoring data measured in 24 areas with different characteristics. Factors showed relatively high correlations than others were indexed to determine infiltration rates of the study area. Among 8 factors(service area, sewer length, sewer diameter, multiplier of sewer length and diameter, number of manholes, population, number of properties, number of households) tested, the multiplier of sewer length and diameter, the number of population and the number of household in each service area indicated higher correlation coefficient(>0.8) than others. The goodness of fitness of linear regressions between infiltration and the factors followed the order: sewer length and diameter(0.68)> population(0.65)> number of household(0.60). Infiltration rates calculated by the multiplier of sewer length and diameter, the number of population and the number of household in each service area were 0.046~1.0396 $m^{3}/d{\cdot}mm-km$, 0.0917~1.7355 $m^{3}/capita{\cdot}d$, 0.196~4.529 $m^{3}/household {\cdot}d$ respectively. After sewerage rehabilitation work of the area, the infiltration rates calculated by above factors with high correlations are expected to be used for comparing effectiveness of the work once they are estimated under the same flow measuring conditions.

• Journal of KIISE:Software and Applications
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• v.35 no.8
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• pp.463-478
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• 2008

Due to the high dimensional problem, typically machine learning algorithms have relied on feature selection techniques in order to perform effective classification in microarray gene expression datasets. However, the large number of features compared to the number of samples makes the task of feature selection computationally inprohibitive and prone to errors. One of traditional feature selection approach was feature filtering; measuring one gene per one step. Then feature filtering was an univariate approach that cannot validate multivariate correlations. In this paper, we proposed a function for measuring both class separability and correlations. With this approach, we solved the problem related to feature filtering approach.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.200-207
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• 2005

This study compares two different methods of measuring brain-BOLD activation. By comparing two different methods of measurement i.e., one method calculating the neural activation area (the number of activated voxels), while the other measured the neural activation intensity (the mean intensity of selected activated yokels), this study identified the more precise method of measuring brain activation which results from the completion of a visuospatial task. 16 right-handed male college students (mean age 23.2 years) participated in this study as subjects. Functional brain images were scanned on them using a 3T MRI single-shot EPI method. No correlation was found between the levels of cognitive performance and number of activated yokels in the activated brain areas. However, a significant correlation was found between the levels of cognitive performance and the mean intensity of selected activated yokels in the parietal, frontal, and other areas. In conclusion, the method of mean intensity was considered a better index of brain activity rather than the activated yokels measurement method.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.137-145
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• 2016

The explosive growth of social networking services based on smart devices popularize these relationships and activities online in accordance with the far larger impact of this on the real life offline, the interest and importance for the online activity is increasing. In this study, factors affecting the SNS activity are defined by object, user, influence direction, influence distance and proposed a method to measure organic terms in effect between the SNS users. Influence Direction and Influence Strength (or Distance) are elaborated by using the existing influence measurement element such as structured data - the number of friends, the difference between the number of contacts - and the new influence measurement element such as unstructured data - gap between the former time and the latter time, preference and type of response behavior - that occur in social network service. In addition, the system for collecting and analysing data for measuring influence from social network service and the process model on the method for measuring influence is tested by using sample data on Facebook and explained the implementation probability.

• Korean Journal of Health Education and Promotion
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• v.15 no.1
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• pp.151-163
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• 1998

The purpose of this study is to find options which reduce the job stress and to enhance morale through a variable analysis, and also apply this data in the legal and administration fields. The data for the research was obtained from 217 dental hygienists working in the dental clinics, dental hospitals and university's dental hospitals' in Seoul. The tool used by this study was a Questionnaire measuring on-the-job stress of dental hygienists, was a modified and revised. The Questionnaire version used to measure bank's job stress and used to suggest options by Dae-ha Yoon(1991). Classification of items for measuring job stress was based on Theoretical Study on Job Stress by Dae-hyon Song(1986). The scale used in study was the two points (yes or no in the job stress) scale measuring for variables. The period of data collection was 30 days from December 4, 1995 to January 5, 1996. The methods of data collection were self-writing, direct visit, and postal Questionnaire answering, 224 copies of Questionnaire data were collected, but only 217 copies were used. 7 copies could not be analyzed, were not used for this study. The data analysis was conducted by SPSS after coding the collected raw data. The general characteristics was obtained from real digits and percentages. In order to analyze the difference of sub-variables against the job stress based on general characteristics. Mean, Standard Deviation, and F test (ANDVA) were conducted. The following were the results of job stress variables: 1. Meaningful variable affecting the working organization, is compensation system(p〈0.03). 2. Meaningful variable affecting the working period, is work overload(p〈0.02). 3. Meaningful variable affecting average patients per day, is the career management and payment(p〈0.04, p〈0.01). 4. Meaningful variable affecting number of staff, is the comrade relationship, role conflict among patients, work overload, and job overload(p〈0.000, p〈0.05, p〈0.04, p〈0.01). The comrade relationship is most affected to the number of staffs aides. 5. Meaningful variables affecting job diversion, are the desire and value, the non-role play, and the environment(p〈0.003, p〈0.02, p〈0.005).

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1121-1129
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• 1988

An economic and efficient system for measuring drop sizes was developed. Pattern recognition technique was used with conventional oil-bath sampling and photographic method. The system was designed to measure and count relatively large number of drops in a very short time, and also to filter out abnormal images such as drops in contact or overlap as well as odd-shaped foreign materials. In this measuring system, most important error originates from the process of converting the original image to the binary image. If the photograph contains a large number of spray drops, the relative size of the pixel to the drops is not infinitesimally small; thus the proper choice of threshold level to convert the original image to the binary image becomes very important. In present case, most of the images lay in one of the two separate bands of brightness level and the arithmetic mean of the most popular brightness levels from each band was chosen as the threshold level. Present image processing system reduces the subjective error by the observers in counting and measuring drops and turns out to be substantially effective. The processing time can be further reduced by improving the hardware system concerned with the digital image coding.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.184-190
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• 2012

Objectives: This study aimed to characterize the nanoparticles produced by welding and grinding processes. Methods: The number concentrations of particles were mapped to determine the distribution of welding fumes in a workplace atmosphere using a hand-held condensation particle counter. An electrical low-pressure impactor was used for measuring the number concentration and particle size distribution. Results: High number concentrations were found around arc cutting and welding (grinding) processes. In the worker's breathing zone, the mean number concentration was 655,000 particles/cm3 and the count median diameter (CMD) was 84 nm with several multi peak distributions (~20, 70, 300 nm). However, at a distance of 3 m from the welding position, the number concentration decreased to 153,000 particles/cm3 with a 70 nm single peak size distribution. During a grinding process, peaks with high concentrations of nanoparticles were temporarily observed. The mean number concentration was 1,520,000 particles/cm3, and the CMD was 30 nm. Nanoparticles (<100 nm) made up 58% and 92% of the aerosols produced by welding and grinding processes, respectively.