• Journal of Intelligence and Information Systems
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• v.16 no.3
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• pp.77-97
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• 2010

Market timing is an investment strategy which is used for obtaining excessive return from financial market. In general, detection of market timing means determining when to buy and sell to get excess return from trading. In many market timing systems, trading rules have been used as an engine to generate signals for trade. On the other hand, some researchers proposed the rough set analysis as a proper tool for market timing because it does not generate a signal for trade when the pattern of the market is uncertain by using the control function. The data for the rough set analysis should be discretized of numeric value because the rough set only accepts categorical data for analysis. Discretization searches for proper "cuts" for numeric data that determine intervals. All values that lie within each interval are transformed into same value. In general, there are four methods for data discretization in rough set analysis including equal frequency scaling, expert's knowledge-based discretization, minimum entropy scaling, and na$\ddot{i}$ve and Boolean reasoning-based discretization. Equal frequency scaling fixes a number of intervals and examines the histogram of each variable, then determines cuts so that approximately the same number of samples fall into each of the intervals. Expert's knowledge-based discretization determines cuts according to knowledge of domain experts through literature review or interview with experts. Minimum entropy scaling implements the algorithm based on recursively partitioning the value set of each variable so that a local measure of entropy is optimized. Na$\ddot{i}$ve and Booleanreasoning-based discretization searches categorical values by using Na$\ddot{i}$ve scaling the data, then finds the optimized dicretization thresholds through Boolean reasoning. Although the rough set analysis is promising for market timing, there is little research on the impact of the various data discretization methods on performance from trading using the rough set analysis. In this study, we compare stock market timing models using rough set analysis with various data discretization methods. The research data used in this study are the KOSPI 200 from May 1996 to October 1998. KOSPI 200 is the underlying index of the KOSPI 200 futures which is the first derivative instrument in the Korean stock market. The KOSPI 200 is a market value weighted index which consists of 200 stocks selected by criteria on liquidity and their status in corresponding industry including manufacturing, construction, communication, electricity and gas, distribution and services, and financing. The total number of samples is 660 trading days. In addition, this study uses popular technical indicators as independent variables. The experimental results show that the most profitable method for the training sample is the na$\ddot{i}$ve and Boolean reasoning but the expert's knowledge-based discretization is the most profitable method for the validation sample. In addition, the expert's knowledge-based discretization produced robust performance for both of training and validation sample. We also compared rough set analysis and decision tree. This study experimented C4.5 for the comparison purpose. The results show that rough set analysis with expert's knowledge-based discretization produced more profitable rules than C4.5.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.40-51
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• 2019

Ginseng has a unique production system that is different from those used for other crops. It is subject to the Ginseng Industry Act., requires a long-term cultivation period of 4-6 years, involves complicated cultivation characteristics whereby ginseng is not produced in a single location, and many ginseng farmers engage in mixed-farming. Therefore, to bring the production of Ginseng in line with GAP standards, it is necessary to better understand the on-site practices of Ginseng farmers according to established control points, and to provide a proper action plan for improving efficiency. Among ginseng farmers in Korea who applied for GAP certification, 77.6% obtained it, which is lower than the 94.1% of farmers who obtained certification for other products. 13.7% of the applicants were judged to be unsuitable during document review due to their use of unregistered pesticides and soil heavy metals. Another 8.7% of applicants failed to obtain certification due to inadequate management results. This is a considerably higher rate of failure than the 5.3% incompatibility of document inspection and 0.6% incompatibility of on-site inspection, which suggests that it is relatively more difficult to obtain GAP certification for ginseng farming than for other crops. Ginseng farmers were given an average of 2.65 points out of 10 essential control points and a total 72 control points, which was slightly lower than the 2.81 points obtained for other crops. In particular, ginseng farmers were given an average of 1.96 points in the evaluation of compliance with the safe use standards for pesticides, which was much lower than the average of 2.95 points for other crops. Therefore, it is necessary to train ginseng farmers to comply with the safe use of pesticides. In the other essential control points, the ginseng farmers were rated at an average of 2.33 points, lower than the 2.58 points given for other crops. Several other areas of compliance in which the ginseng farmers also rated low in comparison to other crops were found. These inclued record keeping over 1 year, record of pesticide use, pesticide storages, posts harvest storage management, hand washing before and after work, hygiene related to work clothing, training of workers safety and hygiene, and written plan of hazard management. Also, among the total 72 control points, there are 12 control points (10 required, 2 recommended) that do not apply to ginseng. Therefore, it is considered inappropriate to conduct an effective evaluation of the ginseng production process based on the existing certification standards. In conclusion, differentiated certification standards are needed to expand GAP certification for ginseng farmers, and it is also necessary to develop programs that can be implemented in a more systematic and field-oriented manner to provide the farmers with proper GAP management education.

• Journal of Popular Narrative
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• v.26 no.3
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• pp.45-86
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• 2020

In this article, the "modernization of the tradition" constructed on the cultural politics and the way in which it appropriated in the korean theatre in the 1970s were analyzed. It is trying to reveal its implications. It is also a work to critically review the aspects of self-censorship in the korean theatre in the 70s. To that end, we looked at the theatre company Minye Theatre, which preoccupied the traditional discussions in the 1970s by creating national dramas. Until now, the evaluation of the theatre company Minye Theatre in the 1970s has focused on the achievement on the directing of Heo Gyu, who promoted the succession and transformation of tradition. However, the traditional ideology constructed in the state-led cultural politics in the 70s and the way in which it was operated cannot be evaluated only in terms of artistic achievement. The ideology of tradition is selected according to the selective criteria of the subject to appropriate tradition. What's important is that certain objects are excluded, discarded, re-elected, re-interpreted and re-recognized in the selection process of selected traditional ideology. This is the situation in the '70s, when tradition was constantly re-recognized amid differences between the decadent and the disorder that were then designated as non-cultural, and led to a new way of appropriate. The nation-led traditional discussion of the '70s legalized the tradition with stable values, one of the its way was the national literary and artistic support. Under the banner of modernization of tradition, theatre company Minye preoccupied the discussions on the tradition and presented folk drama as a new theatre. As an alternative to the crisis of korean theatre at the time, the Minye chose the method of inheriting and transforming tradition. It is noteworthy that Heo Gyu, the representative director of the theatre company Minye, recognized the succession and transformation of traditional performance as both a calling and an experiment. For Heo Gyu, tradition was accepted as an irresistible stable value and an unquestionable calling, and as a result, his performance, filled with excessive traditional practices, became overambitious, especially when it failed to reflect the present-here reality, the repeated use of traditional expression tools resulted in skilled craftsmanship, not artistic creation. The traditional ideology of the 70s unfolds in a new aspect of appropriation in the 80s. In 1986, Son Jin-Cheok, Kim Seong-nyeo, and Yoon Mun-sik, who were key members of the theatre company Minye Theatre, left the theatre to create the theatre company Michu, and secured popularity through Madangnori(popular folk yard theatre). Son Jin-Cheok's Madangnori is overbearing through satire and humor. It gained popularity by criticizing and mocking state power. On the other hand, not only the form of traditional performance, but also the university-centered Madanggeuk movement, which appropriated on the spirit of resistance from the people to its traditional values, has rapidly grown. In the field of traditional discussions of the 70s, Madanggeuk was self-born through appropriation in which the spirit of resistance of the people is used as a traditional value. Madanggeuk as well as Michu that achieved the popularization of Madangnori cannot be discussed solely by the artistic achievement of the modernization of tradition. Critics of korean theatre in response to state-led traditional discussions in the 70s was focused only on the qualitative achievement of performing arts based on artistry. I am very sorry for that. As a result, the popular resistance of the Madanggeuk and the Madangnori were established in the 'difference' with the traditions of the theatre company Minye Theatre. Theatre company Minye Theatre was an opportunity for the modernization of tradition, but the fact that it did not continuously produce significant differences. This is the meaning and limitation of the "tradition" of the theatre company Minye Theatre in the history of korean theatre in the 1970s.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.4
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• pp.101-118
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• 2023

During the COVID-19 pandemic, the utilization rate of neighborhood parks and green spaces increased significantly, and the outbreak served as an opportunity to highlight the values and functions of neighborhood parks and green spaces for urban residents. This study aims to empirically analyze how citizens' movement and the use of neighborhood parks and green spaces changed before and after COVID-19 and examine the social and spatial characteristics that affected these changes. As a research method, first, people's mobility around neighborhood parks and green spaces before and after the COVID-19 pandemic were compared using signal data from telecommunication carriers. Through the analysis of changes in residence time and movement volume, the movement characteristics of citizens after COVID-19 and changes in walking-based park visits were examined. Second, the factors affecting the mobility change in neighborhood parks and green spaces were analyzed. The social and spatial characteristics that affect citizens' visits to neighborhood parks and green spaces before and after COVID-19 were examined through correlation and multiple regression analysis. Subsequently, through cluster analysis, the types of living areas for the post-COVID era were classified from the perspective of the supply and management of neighborhood parks and green spaces services, and directions for improving neighborhood parks and green spaces by type were presented. Major research findings are as follows: First, since the outbreak of COVID-19, activities within 500m of the residence have increased. The amount of stay and walking movement increased in both 2020 and 2021, which means that the need to review the quantitative standards and attractions of neighborhood parks and green spaces has increased considering the changed scope of the walking and living area. Second, the overall number of visits to neighborhood parks and green spaces by walking has increased since the outbreak of COVID-19. The number of visits to neighborhood parks and green spaces centered on the house and the workplace increased significantly. The park green policy in the post-COVID era should be promoted by discovering underprivileged areas, focusing on areas where residential, commercial, and business facilities are concentrated, and improving neighborhood parks and green services in quantitative and qualitative terms. Third, it was found that the higher the level of park green service, the higher the amount of walking movement. It is necessary to use indicators that contribute to improving citizens' actual park green services, such as walking accessibility, rather than looking at the criteria for securing green areas. Fourth, as a result of cluster analysis, five types of neighborhood parks and green spaces were derived in response to the post-COVID era. This suggests that it is necessary to consider the socioeconomic status and characteristics of living areas and the level of park green services required in future park green policies. This study has academic and policy significance in that it has laid the basis for establishing neighborhood parks and green spaces policy in response to the post-COVID era by using various analysis methodologies such as carrier signal data analysis, GIS analysis, and statistical analysis.