• Journal of Intelligence and Information Systems
• /
• v.19 no.2
• /
• pp.125-140
• /
• 2013

We call a data set in which the number of records belonging to a certain class far outnumbers the number of records belonging to the other class, 'imbalanced data set'. Most of the classification techniques perform poorly on imbalanced data sets. When we evaluate the performance of a certain classification technique, we need to measure not only 'accuracy' but also 'sensitivity' and 'specificity'. In a customer churn prediction problem, 'retention' records account for the majority class, and 'churn' records account for the minority class. Sensitivity measures the proportion of actual retentions which are correctly identified as such. Specificity measures the proportion of churns which are correctly identified as such. The poor performance of the classification techniques on imbalanced data sets is due to the low value of specificity. Many previous researches on imbalanced data sets employed 'oversampling' technique where members of the minority class are sampled more than those of the majority class in order to make a relatively balanced data set. When a classification model is constructed using this oversampled balanced data set, specificity can be improved but sensitivity will be decreased. In this research, we developed a hybrid model of support vector machine (SVM), artificial neural network (ANN) and decision tree, that improves specificity while maintaining sensitivity. We named this hybrid model 'hybrid SVM model.' The process of construction and prediction of our hybrid SVM model is as follows. By oversampling from the original imbalanced data set, a balanced data set is prepared. SVM_I model and ANN_I model are constructed using the imbalanced data set, and SVM_B model is constructed using the balanced data set. SVM_I model is superior in sensitivity and SVM_B model is superior in specificity. For a record on which both SVM_I model and SVM_B model make the same prediction, that prediction becomes the final solution. If they make different prediction, the final solution is determined by the discrimination rules obtained by ANN and decision tree. For a record on which SVM_I model and SVM_B model make different predictions, a decision tree model is constructed using ANN_I output value as input and actual retention or churn as target. We obtained the following two discrimination rules: 'IF ANN_I output value <0.285, THEN Final Solution = Retention' and 'IF ANN_I output value ${\geq}0.285$, THEN Final Solution = Churn.' The threshold 0.285 is the value optimized for the data used in this research. The result we present in this research is the structure or framework of our hybrid SVM model, not a specific threshold value such as 0.285. Therefore, the threshold value in the above discrimination rules can be changed to any value depending on the data. In order to evaluate the performance of our hybrid SVM model, we used the 'churn data set' in UCI Machine Learning Repository, that consists of 85% retention customers and 15% churn customers. Accuracy of the hybrid SVM model is 91.08% that is better than that of SVM_I model or SVM_B model. The points worth noticing here are its sensitivity, 95.02%, and specificity, 69.24%. The sensitivity of SVM_I model is 94.65%, and the specificity of SVM_B model is 67.00%. Therefore the hybrid SVM model developed in this research improves the specificity of SVM_B model while maintaining the sensitivity of SVM_I model.

• Journal of Digital Convergence
• /
• v.14 no.10
• /
• pp.455-461
• /
• 2016

This study intends to provide basic evidence needed to establish plans to help disabled children and youth adapt to school by analyzing factors to influence on their school adjustment. To accomplish this goal, raw data of Survey of Disabled People in 2014 conducted by the Ministry of Health and Welfare was utilized for analysis to identify determining factors among level of school, type of school, type of disability, severity of disability, subjective health status, experience of discrimination on disabled children's school adjustment. Results of the analysis are as follows. Level of school, type of school and severity of disability are influencing factors on disabled children's school adjustment. This result shows that the introduction of peer support programs and expansion of special class and auxiliary personnel are needed to assist disabled students' school adjustment.

• Journal of Gifted/Talented Education
• /
• v.20 no.1
• /
• pp.61-77
• /
• 2010

The purpose of this study was to analyze the items that were used in entrance examination for science gifted education center for middle school students by using content analysis and classical item analysis. In content analysis, objective type items exhibited mathematics and physics were dominant. Science giftedness & creativity items were dominant. And essay type items consisted of physics items, have evaluated creative problem solving ability. Item difficulty and discrimination index, on the whole, were appropriate. Comparing with objective type, essay type has higher discrimination index. In correlation analysis between total score and score of each type of items, total score has the highest correlation with essay type items and science giftedness & creativity. It was recommended that mathematics, physics and chemistry items with focusing giftedness & creativity could give some implications for future selection methods of science gifted education center.

• Fire Science and Engineering
• /
• v.29 no.2
• /
• pp.13-19
• /
• 2015

Real scale fire tests was carried out for extinguishing performance evaluation of the wetting agent. The experiment was conducted in accordance with a Class A fire extinguishing test methods specified in the 'Type Approval of the Manual System Fire Extinguisher and Technical Standards of Test'. In addition, the subjects of this experiment were the wood flour and rice husk. Fire-fighting water, the three kinds of wetting agents used in the country and this study was used, was undertaken to determine a clear discrimination of the water and wetting agent. In the experimental results, it was confirmed that the internal temperature is maintained long time in the case of water. The internal temperature were rapidly lowered in the experiment of wetting agents. Therefore, the discrimination of extinguishing ability was confirmed by the temperature distribution in accordance with time. Based on the results of this experiment, this study is expected to be used as a underlying material on presenting a method of optimized performance evaluation of wetting extinguishing agent.

• The Journal of Korean-Japanese National Studies
• /
• no.32
• /
• pp.215-275
• /
• 2017

In the absence of the alternative public space of women in Japan, the experience of the "Bongseonhwa" was interpreted as the public domain of Japanese society as a public domain, a confession that focused on gender discrimination in the patriarchal system of Japan, Most of the enemy discourse is. These alienated discourses are the product of the efforts of women in Japan who do not want to forget about the traces and memories that can not be incorporated into the big narrative. It can not be denied that the women in the society of Japan have been excessively excluded and alienated by national ideology and patriarchal ideology. The meaning of presenting them through "Bongsinghwa" is the resistance of the minority, and it is the expression way of reconstructing and strengthening the identity of the women, and it is said to be a space of symbolic meaning. It is further clarified that it is based on a narrative that creates a new life area for coexistence with Japanese society, on the other hand, by constantly searching for the linkage with the motherland, held by women in Japan. As a result, between public social phenomena and private living space, confirmed that it conflicts with repetitive internal contradiction of controlling power and confirmed that complicated and detailed material of women living in Japan who undergo double discrimination What has been expressed over a period is considered to be a resistance expression and a will of expression of reconciliation to coexist with Japanese society. I have attempted to analyze the confessed alienated discourse of "Bongsinghwa" by classifying it as . As a result, it is confirmed that the public social phenomenon and the private life space are confronted with the repetitive internal contradictions of the power of domination, and the expression of the complex and detailed material of the discriminated women in Japan over a long period of time is a resistance to symbiosis with Japanese society And the will of the conversation.

• Journal of Korean Society of Forest Science
• /
• v.83 no.2
• /
• pp.175-190
• /
• 1994

In order to get fundamental information for prediction of landslide hazard, both forest and site factors affecting slope stability were investigated in many areas of active landslides. Twelve descriptors were identified and quantified to develop the prediction model by multivariate statistical analysis. The main results obtained could be summarized as follows : The main factors influencing a large scale of landslide were shown in order of precipitation, age group of forest trees, altitude, soil texture, slope gradient, position of slope, vegetation, stream order, vertical slope, bed rock, soil depth and aspect. According to partial correlation coefficient, it was shown in order of age group of forest trees, precipitation, soil texture, bed rock, slope gradient, position of slope, altitude, vertical slope, stream order, vegetation, soil depth and aspect. The main factors influencing a landslide occurrence were shown in order of age group of forest trees, altitude, soil texture, slope gradient, precipitation, vertical slope, stream order, bed rock and soil depth. Two prediction models were developed by magnitude and frequency of landslide. Particularly, a prediction method by magnitude of landslide was changed the score for the convenience of use. If the total store of the various factors mark over 9.1636, it is evaluated as a very dangerous area. The mean score of landslide and non-landslide group was 0.1977 and -0.1977, and variance was 0.1100 and 0.1250, respectively. The boundary value between the two groups related to slope stability was -0.02, and its predicted rate of discrimination was 73%. In the score range of the degree of landslide hazard based on the boundary value of discrimination, class A was 0.3132 over, class B was 0.3132 to -0.1050, class C was -0.1050 to -0.4196, class D was -0.4195 below. The rank of landslide hazard could be divided into classes A, B, C and D by the boundary value. In the number of slope, class A was 68, class B was 115, class C was 65, and class D was 52. The rate of landslide occurrence in class A and class B was shown at the hige prediction of 83%. Therefore, dangerous areas selected by the prediction method of landslide could be mapped for land-use planning and criterion of disaster district. And also, it could be applied to an administration index for disaster prevention.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.27 no.3
• /
• pp.129-149
• /
• 2016

The purpose of this study is to examine in depth the personal experience of Instructor during National Competence Standards (NCS) Curriculum at Department of Library and Information Science. We conducted in depth interview (FGI) with participants who had recently experienced and data analysis was undertaken. We hope this study that an application of NCS would be activated fully in Library, educational institutes and qualifying examination institutes and that diverse feedbacks from related parties would makes leading to a better updated version of NCS development. As a result, First, The instructor had generally familiar with the background and purpose of the NCS. and they issued the inadequacies of job elements, non-reflection of the opinion on field education, the problems of classification of NCS. second, In the experience of NCS curriculum operating, There were the paperwork burden, Problems of methods of evaluation, evaluation period discrimination, the need to well communication with students. Third, In the problems on the NCS Curriculum operating, we found that there were The need on the proper Class size/hour, additional education, re-evaluation, Support system for NCS Curriculum operation, tools for practice, discrimination between relative evaluation and NCS evaluation, Enhancement for Competence/Standards. Fourth, On The ways of improving for NCS curriculum, We found that There were Class size, Support tools for practice, The improvement Competence/elements/standards based on LIS characteristic. The result of this study may contribute for improving the overall environment Based upon FGI analysis, several new directions for NCS education in the filed LIS curriculum are suggested.

• 한국사회정책
• /
• v.23 no.2
• /
• pp.141-172
• /
• 2016

This study examines the employment conditions and labour experience of elementary after-school care teachers in South Korea. Based on the empirical data collected through in-depth interviews with after-school care teachers in Gwangju Metropolitan City, the study considers multifaceted problems faced by after-school care teachers in their workplace. The after-school care class is part of educational policies initiated and rapidly expanded by the Ministry of Education, resulting in the substantial increase of non-regular school workers. The irregularization of after-school care teachers illustrates that the common problems faced by female non-regular workers, such as social discrimination, exclusion and inequality, are also transplanted into the typical public sector. In the case of Gwangju Metropolitan City, during the past two years there have been evident increases both in under 15-hour short time contract care teachers and outsourcing of care classes. Temporary part-time contract care teachers suffer relentless job insecurity and experience poor working conditions, exclusion and discrimination within the workplace and labour alienation. In order to minimize the organized resistance of care teachers, school authorities implicitly individualize and isolate care teachers through hierarchization, the division of labour and the spatial division of classes between indefinite and temporary contract teachers.

• Journal of the Economic Geographical Society of Korea
• /
• v.13 no.1
• /
• pp.111-125
• /
• 2010

For a shift to a new paradigm that allows restoring solidarity among class, gender, and race, it is necessary to closely investigate the differences between Marxist view and poststructuralist view which provide theoretical basis for labor movement and for feminist movement, respectively. However, little effort has been devoted to this task. This paper critically compares two best wellknown geographers; Harvey's class-centered theory and Gibson-Graham's post-structuralist feminist approach by focusing on their understandings of "difference". David Harvey argues that racial/gender discrimination is another form of class-exploitation and puts priority on the solidarity based on the commonality of labor. On the contrary Gibson-Graham argues that the privileging of class above all else marginalizes other political dimension, and proposes the deconstruction of hegemonic discourse of capitalism and the construction of "community economies", Based on the critical survey of both theories, I propose that understanding the role that spatiality plays in capital accumulation process is the key to compromise two different approaches.

• Journal of the Korean Chemical Society
• /
• v.52 no.3
• /
• pp.295-302
• /
• 2008

In this study, the test that were used in entrance examination for chemistry class in a Science-Gifted Education Center for middle school students were analyzed by using criteria for identification and measurement of scientific giftedness and a classical test theory. The result of analysis exhibited that most of problems measured more than two elements of scientific giftedness and required applications of scientific knowledge of middle school level to solve problems. In the analysis of sub-elements of scientific giftedness, originality, fluency in creativity and finding problems/formulating hypothesis, planning inquiry, interpreting data in science process skills were dominant while drawing conclusion and generalization processes were lacking. In correlation analysis between total score and each type of problems, total score was most influenced by the problems measuring science inquiry linked with scientific knowledge. Item difficulty is moderately high and item discrimination is moderate.