• Korea journal of population studies
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• v.24 no.1
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• pp.67-90
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• 2001

Korea National Statistical Office(KNSO) estimated period birth rates, period death rates, and probability of dying for infant(q$q_{0}$) at period life table, considering the unregistered infant deaths. As Ministry of Health and Welfare(MHW) conducted 1993 and 1996 birth cohort infant death surveys. KNSO re-estimated infant mortality levels(especially q$q_{0}$). For the re-estimation, reference data were derived from death registration. MHW surveys, death registration of developed countries. Model Life Tables, and Life Table for Japan. Seventeen simulations were made by the combination of estimation methods and reference data. The final $q_{0}$ was estimated based on the relationship between $q_{0}$ of MHW 1993 survey and $q_{1-4}$ of registered deaths for the period of 1971~1997. For 1993, $q_{0}$ was calculated directly from the 1993 MHW survey and interpolation and extrapolation were made for 1995 and 1997 using the relative decrease rates of $q_{0}$ between 1993 and 1996 MHW surveys. Utilizing the formular of Coale-Demeny North Model, $q_{0}$ was transformed into $m_{0}$ for the period 1971~1997. Finally, cremation data are found to be very useful for the estimation of 1998 infant mortality level by supplementing unregistered infant deaths, especially neonatal deaths. Furthermore, they are found to be very useful to produce fetal and perinatal death statistics.

• Journal of Digital Convergence
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• v.12 no.7
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• pp.327-336
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• 2014

This study aims to identify factors to affect regular utilization status of medical care in cardio-cerebrovascular patients. The research selected 770 cardio-cerebrovascular patients among surveyees from the Korea Health Panel 2010. We analyzed states of medical care utilization using descriptive statistics. Logistic regression analysis was used to examine the main factors associated with regular utilization status of medical care in cardio-cerebrovascular patients. In result, the significant factors associated with regular utilization status of medical care in cardio-cerebrovascular patients were age, education level, household income level. CCI, presence or absence of high risk drinking, and presence or absence of obesity. There's a high probability that patients aged between 60 and 69, equal to and higher than those of high school graduate in education level, upper middle class in household income, the higher CCI, absence of high risk drinking, presence of obesity utilize medical care services more regularly. Therefore, it is necessary to develop effective program and individualized approach for patients using lesser periodical medical care and patients with high risk drinking problem. In the future, these findings can be used an important data for healthcare policy and assessment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.217-225
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• 2010

Most of the steel bridges in Korea are being currently designed by the allowable stress design method that uses the conventional deterministic factors of safety. However the limit state design based on the concept of probability, statistics and reliability engineering is becoming very popular as a global standard deign method, leading the rational and economic bridge design. As part of the fundamental research to establish the load and resistance factor design(LRFD) of steel bridges considering domestic environmental conditions and regional characteristics, an experimental design is conducted by applying AASHTO-LRFD specification especially to a steel closed-box girder, which occupies relatively a large portion of steel bridges in Korea. Throughout the experimental design according to various sectional changes, some of the issues to be considered in the LRFD design of a composite steel closed-box girder bridge are examined. In this process, an Excel-based design verification program is developed for easy computation and prevention of errors. Quantitative reliability levels of the bridge sections designed by LRFD are also estimated using a reliability analysis method, and compared with the target reliability indexes applied in the LRFD design to verify the validity of the procedure and methodology used in this study.

• Survey Research
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• v.11 no.2
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• pp.1-28
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• 2010

This paper reports the results of the 2009 Internet volunteer panel version of the social survey conducted by Statistics Korea (Korea National Statistical Office). Authors identify socio-psychological characteristics of Internet survey volunteers and present quantitative evaluation of the propensity adjustment weighting method intended to remove Internet sample bias. The nine criteria used for propensity adjustment were regions, urban/rural, gender, age, education, consumer satisfaction, views on income distribution, newspaper access and Internet news access. Propensity adjustment weighting based on the logit model and rim weights were applied to the online survey of 2,903 respondents using the face-to-face area sample data of 37,049 respondents as reference. A total of 106 items were used for evaluating the propensity adjustment weighting methods. The results showed that in 80% of survey items the propensity adjustment weighting yielded better estimates compared to simple demographic weighting. This suggests that Internet surveys by volunteer panels are useful for conducting the general social study in Korea. The reference survey data for this study contains several items on social-psychological behaviors and attitudes, is large in size and obtained by probability sampling. Thus it may be utilized in propensity adjustment of other Internet surveys.

• Communications of Mathematical Education
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• v.34 no.1
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• pp.1-15
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• 2020

Today's healthcare, intelligent robots, smart home systems, and car sharing are already innovating with cutting-edge information and communication technologies such as Artificial Intelligence (AI), the Internet of Things, the Internet of Intelligent Things, and Big data. It is deeply affecting our lives. In the factory, robots have been working for humans more than several decades (FA, OA), AI doctors are also working in hospitals (Dr. Watson), AI speakers (Giga Genie) and AI assistants (Siri, Bixby, Google Assistant) are working to improve Natural Language Process. Now, in order to understand AI, knowledge of mathematics becomes essential, not a choice. Thus, mathematicians have been given a role in explaining such mathematics that make these things possible behind AI. Therefore, the authors wrote a textbook 'Basic Mathematics for Artificial Intelligence' by arranging the mathematics concepts and tools needed to understand AI and machine learning in one or two semesters, and organized lectures for undergraduate and graduate students of various majors to explore careers in artificial intelligence. In this paper, we share our experience of conducting this class with the full contents in http://matrix.skku.ac.kr/math4ai/.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.443-450
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• 2004

This study developed a prediction model of debris flow to predict a landslide probability on natural terrain composed of the Tertiary sedimentary and volcanic rocks using a logistic regression analysis. The landslides data were collected around Pohang, Gyeongbuk province where more than 100 landslides were occurred in 1998. Considered with basic characteristics of the logistic regression analysis, field survey and laboratory soil tests were performed for both slided points and not-slided points. The final iufluential factors on landslides were selected as six factors by the logistic regression analysis. The six factors are composed of two topographic factors and four geologic factors. The developed landslide prediction model has more than $90\%$ of prediction accuracy. Therefore, it is possible to make probabilistic and quantitative prediction of landslide occurrence using the developed model in this study area as well as the previously developed model for metamorphic and granitic rocks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.245-258
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• 2016

In this study the geotechnical system response probabilities (SRP) of the failure modes caused by the interal erosion in three dams with different histories of defects in Korea were analyzed via the internal erosion toolbox developed by USACE. The calculated values of SRP were compared with the values reported for other dams in worldwide and also the statistics on the past failures of dams and embankments in Korea. The calculated values of SRP related to the internal erosion adjacent to the conduits or spillway structures are as high as in the order of $10^{-5}$ that is significantly greater than the SRP values related to other mechanisms of internal erosion. The statistical data showing that the interal erosion adjacent to the structure is the most frequent cause of the failure of the dam in Korea could be a collateral evidence of this finding. In contrast, the values of SRP related to the internal erosion through foundation, one of the major causes of dam failure in worldwide, are relatively as low as in the order of $10^{-7}$. This result could be comparable with the rareness of the failure cases of dam caused by the internal erosion through foundation in Korea.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.371-376
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• 2006

The initial radius of sphere decoder has great effect on the bit error rate performance and computational complexity. Until now, it has been determined either by considering the statistical property of channel or by using of MMSE solution. The initial radius obtained by using statistical property of channel includes the lattice point corresponding to the transmit signal vector with very high probability. The method using MMSE solution first calculates out the MMSE solution of the received signal, then maps the hard decision of this solution into the received signal space, and finally the distance between the mapped point and the received signal is selected as the initial radius of the sphere decoding. In this paper, we derive a simple equation for initial radius selection which uses statistical property of channel and compare it with the method using MMSE solution. To compare two methods we define new metric 'Tightness'. Through the simulation, we observe that in low and moderate SNR region, the method using MMSE solution provides more complexity reduction for decoding while in high SNR region, the method using channel statistics is better.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.161-169
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• 2020

This study investigated the effects and relationships of various stress, school life adjustment and happiness factors among middle school and high school adolescents. The structural model group effects between boy and girl groups were also investigated. Data was employed from the 'Korean Children and Youth Well-Being Index Survey, 2018' while subjects of the analysis included 5,144 students. Based on the education statistics data, the sample was collected by probability proportional to size. Results utilizing structural equation modeling and multigroup analysis showed that first, school stress, friend stress, and look stress had significant effects on adolescent happiness. School life adjustment had positive significant effects on adolescents' happiness. Parent stress, money stress and school stress had significant effects on school life adjustment. Second, the mediating effect of school life adjustment between stress and happiness was significant with parent, school stress, and financial stress. Third, results of the multi-group analysis by level and gender showed that the structure was similar between boys and girls, with the only differences among mediating effects. Boys had significant mediating effects by school stress, and financial stress, while girls had significant mediating effects by school stress, financial stress, and parent stress. Finally, based on the results of the study, practice and policy implications were suggested to support the promotion of adolescents' happiness.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.121-127
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• 2020

The era of the Fourth Industrial Revolution is increasingly demanding mathematical competencies for virtual reality (VR), artificial intelligence (AI) and the like. In this context, this study intended to identify the basic mathematical competency levels of university freshman students in radiology department and to provide basic data thereon. For this, the diagnostic assessment of basic learning competencies for the domain of mathematics was conducted from June 17, 2019 to June 28, 2019 among 78 freshman students of radiology department at S university and D university. As a result, the university students' overall basic mathematical competency levels were diagnosed to be excellent. However, their levels in the sectors of the geometry and vector and the probability and statistics were diagnosed to be moderate, with the mean scores of 2.61 points and 2.64 points, respectively, which were found to be lower than those of the other sections. As for basic mathematical competency levels according to genders, the levels of male students and female students were diagnosed to be excellent, with the mean scores of 17.48 points and 16.29 points, respectively, showing no statistically significant difference (p>0.05). Given the small number of subjects and regional restriction, there might be some limitations in the generalization of the findings of the present study to all university freshman students and all departments. The above results suggest that it is necessary to implement various programs such as student level-based special lectures for enhancing basic mathematical competencies relating to major in order to improve the basic mathematical competencies of freshman students in radiology department, and that it is necessary to increase the students' mathematical competencies by offering major math courses in the curriculum and applying teaching-learning methods matching students' levels.