• Journal of radiological science and technology
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• v.39 no.3
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• pp.323-328
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• 2016

The spatial dose distribution was measured with ionization chamber as preliminary study to evaluate operator dose and to study dose reduction during neuro-interventional procedures. The zone of operators was divided into four area (45, 135, 225, and 315 degree).We supposed that operator exist on the four area and indicated location of critical organs(eyes, breast, gonad). The spatial doses were measured depending on distance( 80, 100, 120, and 140 cm) and location of critical organs. The spatial doses of area of 225 degree were 114.5 mR/h (eyes location), 143.1 mR/h (breast location) and 147 mR/h (gonad location) in 80 cm. When changed location of x-ray generator, spatial dose increased in $18.1{\pm}10.5%$, averagely. We certified spatial dose in the operator locations, Using the results of this study, It is feasible to protect operator from radiation in neuro-interventional procedures.

• Journal of the Korean Magnetics Society
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• v.20 no.2
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• pp.52-60
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• 2010

The changes of magnetic flux density distribution and the degree of magnetic anomaly on the ground surface by underground fracture zones and empty spaces had been investigated through the variations of the measuring heights. The magnetic flux density distributions were monitored for the ground surfaces of fracture zones, empty spaces and tunnels by fluxgate-type magnetometer. The fracture zones showed the magnetic anomaly with (+) and (-) peak-pairs in the magnetic flux distribution measured at 0.15 m height from the ground surface, and this anomaly disappeared at the height of 1.15 m. The underground empty spaces and tunnels showed the decrease of magnetic flux densities, where the degree of this density decrease diminished with the increase of the underground depth. And, the existence and size of underground empty spaces, such as tunnels and sink holes, could be monitored by the phenomena of this decreasing flux density.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.927-934
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• 2022

This study attempted to find out the degree of agreement between ultrasound image findings along with analysis of attenuation index and scatter distribution index values within tissues through quantitative measurement analysis using liver ultrasound images. From August 2022 to October 2022, liver ultrasound was performed on 45 patients who were suspected of having fatty liver and who received a prescription for liver ultrasound. As a result of the study, as a result of analyzing the agreement between the ultrasound image findings and the tissue attenuation index, the Kappa value was 0.82 (p<0.05), showing a very high agreement between the two examination methods. In addition, as a result of the agreement analysis between the ultrasound image findings and the scatter distribution index in the tissue, the Kappa value was 0.642 (p<0.05), showing high agreement between the two examination methods. At the time of fat liver prediction, the use of liver ultrasound findings and quantitative ultrasonography techniques, such as intra-tissue attenuation index and intra-tissue scatter distribution index, may be helpful in determining the degree of progression of fatty liver patients.

• Journal of the Korean Geographical Society
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• v.40 no.5 s.110
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• pp.584-593
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• 2005

The spatial and temporal variations of heating degree-days (HDDs) and cooling degree-days (CDDs) are closely related with the temperature field. The spatial distribution of 30-year mean HDDs shows that the higher values locates in the northern part of South Korea while the lower values locates in the southern part. The 30-year mean CDDs shows a more randomized distribution than the HDDs. The changing trends of HDDs and CDDs show a different feature: HDDs have a distinct decreasing trend while CDDs have an insignificant change. The decreasing trends of HDDs are consistent over South Korea and most of stations have experienced the statistically significant change. As significant changing areas of HDDs are much broader than those of annual mean temperature, HDDs can be more useful than annual mean temperature to detect the climate change impact on a regional level. In other words, an insignificant change on the mean temperature field can induce the significant change of thermal climatology in a region. The temporal pattern of climatic departure index (CDI) for South Korea HDDs series shows a general decreasing, but a sharp increase during recent years. The drastic decrease of HDDs induces higher CDI indicating larger variability among stations. However, the decrease of South Korea HDDs series cannot totally attribute to the global warming due to urban effects. By the early 1980s, there were no big differences of HDDs between urban and rural series, but later the differences are getting larger. This was expected to be with the intensification of urbanization in South Korea. However, still there is a decreasing trend of HDDs for rural stations.

• Journal of IKEEE
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• v.24 no.2
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• pp.529-535
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• 2020

As the main technology of the 4th industrial revolution, immersive 360-degree video contents are drawing attention. The market size of immersive 360-degree video contents worldwide is projected to increase from $6.7 billion in 2018 to approximately $70 billion in 2020. However, most of the immersive 360-degree video contents are distributed through illegal distribution networks such as Webhard and Torrent, and the damage caused by illegal reproduction is increasing. Existing 2D video industry uses copyright filtering technology to prevent such illegal distribution. The technical difficulties dealing with immersive 360-degree videos arise in that they require ultra-high quality pictures and have the characteristics containing images captured by two or more cameras merged in one image, which results in the creation of distortion regions. There are also technical limitations such as an increase in the amount of feature point data due to the ultra-high definition and the processing speed requirement. These consideration makes it difficult to use the same 2D filtering technology for 360-degree videos. To solve this problem, this paper suggests a feature point extraction and identification technique that select object identification areas excluding regions with severe distortion, recognize objects using deep learning technology in the identification areas, extract feature points using the identified object information. Compared with the previously proposed method of extracting feature points using stitching area for immersive contents, the proposed technique shows excellent performance gain.

• 한국노년학
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• v.32 no.2
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• pp.649-668
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• 2012

The purpose of this study ahead of the aging society in Korea to prevent problems of the elderly aged new addiction Internet Addiction and identify factors affecting the quantitative increase and qualitative improvement beyond that aims to promote. To this end, residents in Seoul over the age of 60's targets, local welfare, cultural centers, senior centers and other research in the area through one-on-one interviews were conducted the survey. Findings The average degree of Internet addiction elderly 36.16 points (SD = 10.02) and the distribution of at least 20 points to 65 points, respectively. Factors affecting the degree of Internet addiction as a computer time (β = .248, p <.001), mon allowance (β = .180, p <.01), age (β = .139, p <.01) and social support (β = .087, p <.05), self-efficacy (β = - .078, p <.05), most used location (β = - .116, p <.05), degree of family relationship (β = - .147, p <.01), housing type (β = - .153, p <.01), were of the order, this factor was 17.6% of the variance. In other words, the more computer time, the higher the age, the more mon allowance, housing is not self, the lower the degree of family relationship, the house is not a place most used, lower self-efficacy, social support is high As increasing the degree of Internet addiction was thought to be the two predictor variables. Survey results to target the elderly through the Internet addiction group psychotherapy program implementation, and production and distribution of manuals related to Internet use and addiction-related factors, according to the case-by-case Case management services are tailored to be done, and the Internet in general for seniors potential risks related to use in training and preventive services for the elderly will need to be made.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1263-1274
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• 2013

VaR (value at risk), which represents the expectation of the worst loss that may occur over a period of time within a given level of confidence, is currently used by various financial institutions for the purpose of risk management. In the majority of previous studies, the probability of return has been modeled with normal distribution. Recently Chen et al. (2010) measured VaR with asymmetric Laplacian distribution. However, it is difficult to estimate the mode, the skewness, and the degree of variance that determine the shape of an asymmetric Laplacian distribution with limited data in the real-world market. In this paper, we show that the VaR estimated with (symmetric) Laplacian distribution model provides more accuracy than those with normal distribution model or asymmetric Laplacian distribution model with real world stock market data and with various statistical measures.

• The Mathematical Education
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• v.59 no.1
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• pp.47-62
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• 2020

Understanding the concept of probability distribution becomes more important. We considered probabilities defined in the sample space, the definition of discrete random variables, the probability of defined discrete probability distribution, and the relationship between them as knowledge of discrete probability distribution, and investigated the understanding degree of the mathematics preservice teachers. The results are as follows. Firstly, about 70% of preservice teachers who participated in this study expressed discrete probability distribution graphs in ordered pairs or continuous distribution. Secondly, with regard to the two factors for obtaining discrete probability distributions: probability for each element in the sample space and the concept of random variables that convert each element in the sample space into a real value, only 13% of the preservice teachers understood and addressed both factors. Thirdly, 39% of the preservice teachers correctly responded to whether different probability distributions can be defined for one sample space. Fourthly, when the probability of each fundamental event was determined to obtain the probability distribution of the discrete random variables defined in the undefined sample space, approximately 70% habitually calculated by the uniform probability. Finally, about 20% of preservice teachers understood the meaning and relationship of binomial distribution, discrete random variables, and sample space. In relation, clear definitions and full explanations of concept need to be provided from textbooks and a program to improve the understanding of preservice teachers need to be developed.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.429-438
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• 2022

This study evaluated the effect of the degree of weathering on the particle size distribution and the amount of fine particles generated in the aggregate production process during the crushing of igneous rock. Rock samples were collected from three areas with differences in strength from the Schmith hammer measurement at the aggregate quarry in Geochang, Gyeongsangbuk-do. After crushing with a jaw crusher under the same conditions in laboratory, particle size analysis, mineral analysis, chemical analysis, and weathering index were calculated. The Schmidt hammer measurements were 56, 28, and <10, and the CIA and CIW values of weathering index were also different, so the rock samples were classified into hard rock, soft rock, and weathered rock according to the weathering degree. It shows a smaller particle size distribution toward weathered rocks under the microscope, and the proportion of altered clay minerals such as sericite increased. The composition of feldspar and quartz was high for hard rock, and the ratio of muscovite and kaolinite was low. As a result of the crushing of the jaw crusher, hard rock produced a lot of coarse crushed material (13.2mm), while soft rock and weathered rock produced fine crushed material (4.75mm). The former showed the characteristics of the beta distribution curve, and the latter showed the bimodal distribution curve. The production of fine rock particles (based on 0.71mm of sieve, wt. %) increased to 13%<21%<22% in hard rock, soft rock, and weathered rock, and the greater the degree of weathering, the more fine rock particles were generated. The fine particles are recovered by the operation of the sand unit in the wet aggregate production process. Therefore, in order to minimize the amount of sludge generated in the aggregate production process, it was judged that a study on the optimal operation of cyclones could be necessary.

• Health Policy and Management
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• v.11 no.2
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• pp.85-122
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• 2001

This study compared and analyzed the effect of income-redistribution, collecting data on the basis of the estimated details of insurance contribution and individual money wage lists for each one year before and after the combination of medical insurance program for industrial workers, by systematic sampling, extracting 4,160 families(14,764 people) among people applied to medical insurance program for self employees in Taegu City on the basis of Oct. 1st in 1998 with 227 associations of medical insurance program for self employees and medical insurance program for government employees and private school teachers combined, comparing the effect of income redistribution of before and after the combination of medical insurance program for self employees. The insurance contribution by household after the combination of medical insurance program for self employees showed the increase rate of average 20.9%, among them households of 68.8% increased and 31.2% decreased. The effect of income-redistribution was more positive because the degree of inequality was more deepened from 0.64 of the before-combination to 0.45 of the after-one in decile distribution ratio, from 0.26 to 0.34 in Gini -coefficient. Decile distribution ratio on the basis of insurance benefits by household was from 0.09 in the before-combination to 0.14 in the after-one, Gini-coefficient from 0.16 in the before-combination to 0.57 in the after-one was a little lowered. And decile distribution ratio of insurance benefits on the basis of insurance contribution was higher from 1.08 in the before-combination to 1.23 in the after-one, concentration index was a little lowered from 0.14 to 0.11, the effect of income-redistribution was improved in the phase of insurance benefits. The income-transfer rate of medical insurance program for self employees (the occupied rate of insurance benefits/ the occupied rate of insurance contribution) showed a lower trend in all of the before and after-combination towards upper classes, it was known that the income-transfer rate was higher from 1st degree to 7th degree in the after-combination in comparison with the before-one, but the effect of income¬redistribution was high because the income-transfer rate was lowered from 8th degree to 10th degree. The rate of medical insurance benefits (insurance benefits/ insurance contribution) increased from 0.79 in the before-combination to 1.07 in the after-one, and showed over 1.0 under 3th degree before the combination, but all of it was higher than 1.0 under 7th degree after the combination, the after-combination was more improved than the before-one in view of the rate of insurance benefits. As the result of above, on the basis of Oct. 1st in 1998 that 227 associations of medical insurance program for self employees was combined into one, we could say that the equality of imposing medical insurance contribution was more re-considered in the after-combination than in the before-one. But this study analyzed with classes divided, anyway, on the basis of insurance contribution, we have limit in explaining the correct effect of income-redistribution, because it was not analyzed according to classes of income, though it helps to analogize the effect of income-redistribution. So there must be analysis about the effect of income-redistribution, on the basis of the system, building up the system to grasp the correct income of the insureds of medical insurance program for self employees.