• Sleep Medicine and Psychophysiology
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• v.27 no.2
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• pp.67-76
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• 2020

Objectives: Brain maturation involves brain lateralization and asymmetry to achieve efficient information processing and cognitive controls. This study elucidates normal brain maturation change during the gap between ages 6-9 and age 14-17 using resting EEG. Methods: An EEG dataset was acquired from open source MIPDB (Multimodal Resource for Studying Information Processing in the Developing Brain). Ages 6-9 (n = 24) and ages 14-17 (n = 26) were selected for analysis, and subjects with psychiatric illness or EEG with severe noise were excluded. Finally, ages 6-9 (n = 14) and ages 14-17 (n = 11) were subjected to EEG analysis using EEGlab. A 120-sec length of resting EEG when eyes were closed was secured for analysis. Brain topography was compartmentalized into nine regions, best fitted with brain anatomical structure. Results: Absolute power of the delta band and theta band in ages 6-9 was greater than that of ages 14-17 in the whole brain, and, also is relative power of delta band in frontal compartment, which is same line with previous studies. The relative power of the beta band of ages 14-17 was greater than that of ages 6-9 in the whole brain. In asymmetry evaluation, relative power of the theta band in ages 14-17 showed greater power in the left than right frontal compartment; the opposite finding was noted in the parietal compartment. For the alpha band, a strong relative power distribution in the left parietal compartment was observed in ages 14-17. Absolute and relative power of the alpha band is distributed with hemispheric left lateralization in ages 14-17. Conclusion: During the gap period between ages 6-9 and ages 14-17, brain work becomes more complicated and sophisticated, and alpha band and beta band plays important roles in brain maturation in typically developing children.

• Journal of Intelligence and Information Systems
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• v.27 no.1
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• pp.65-82
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• 2021

Stock market investors are generally split into foreign investors, institutional investors, and individual investors. Compared to individual investor groups, professional investor groups such as foreign investors have an advantage in information and financial power and, as a result, foreign investors are known to show good investment performance among market participants. The purpose of this study is to propose an investment strategy that combines investor-specific transaction information and machine learning, and to analyze the portfolio investment performance of the proposed model using actual stock price and investor-specific transaction data. The Korea Exchange offers daily information on the volume of purchase and sale of each investor to securities firms. We developed a data collection program in C# programming language using an API provided by Daishin Securities Cybosplus, and collected 151 out of 200 KOSPI stocks with daily opening price, closing price and investor-specific net purchase data from January 2, 2007 to July 31, 2017. The self-organizing map model is an artificial neural network that performs clustering by unsupervised learning and has been introduced by Teuvo Kohonen since 1984. We implement competition among intra-surface artificial neurons, and all connections are non-recursive artificial neural networks that go from bottom to top. It can also be expanded to multiple layers, although many fault layers are commonly used. Linear functions are used by active functions of artificial nerve cells, and learning rules use Instar rules as well as general competitive learning. The core of the backpropagation model is the model that performs classification by supervised learning as an artificial neural network. We grouped and transformed investor-specific transaction volume data to learn backpropagation models through the self-organizing map model of artificial neural networks. As a result of the estimation of verification data through training, the portfolios were rebalanced monthly. For performance analysis, a passive portfolio was designated and the KOSPI 200 and KOSPI index returns for proxies on market returns were also obtained. Performance analysis was conducted using the equally-weighted portfolio return, compound interest rate, annual return, Maximum Draw Down, standard deviation, and Sharpe Ratio. Buy and hold returns of the top 10 market capitalization stocks are designated as a benchmark. Buy and hold strategy is the best strategy under the efficient market hypothesis. The prediction rate of learning data using backpropagation model was significantly high at 96.61%, while the prediction rate of verification data was also relatively high in the results of the 57.1% verification data. The performance evaluation of self-organizing map grouping can be determined as a result of a backpropagation model. This is because if the grouping results of the self-organizing map model had been poor, the learning results of the backpropagation model would have been poor. In this way, the performance assessment of machine learning is judged to be better learned than previous studies. Our portfolio doubled the return on the benchmark and performed better than the market returns on the KOSPI and KOSPI 200 indexes. In contrast to the benchmark, the MDD and standard deviation for portfolio risk indicators also showed better results. The Sharpe Ratio performed higher than benchmarks and stock market indexes. Through this, we presented the direction of portfolio composition program using machine learning and investor-specific transaction information and showed that it can be used to develop programs for real stock investment. The return is the result of monthly portfolio composition and asset rebalancing to the same proportion. Better outcomes are predicted when forming a monthly portfolio if the system is enforced by rebalancing the suggested stocks continuously without selling and re-buying it. Therefore, real transactions appear to be relevant.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.6
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• pp.27-42
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• 2020

Startup accelerators have emerged as new investment entities that help early startups, which are not easy to survive continuously due to lack of funds, commercialization capabilities, and experiences. As their positive performance on early startups and the ecosystem has been proven, the number of early startups which want to receive their investment is also increasing. However, they are vaguely preparing to attract accelerators' investment because they do not have any information on what factors the accelerators consider important. In addition, researches on startup accelerators are also at an early level, so there are no remarkable prior studies on factors that decide on investment. Therefore, this study aims to help startups prepare for investment attraction by looking at what factors are important for accelerators to invest, and to provide meaningful implications to academia. In the preceding study, we derived five upper level categories, 26 lower level accelerators' investment determinants through the qualitative meta-synthesis method, secondary data analysis, observation on US accelerators and in-depth interviews. In this study, we want to derive important implications by deriving priorities of the accelerators' investment determinants. Therefore, we used AHP that are evaluated as the suitable methodology for deriving importance and priority. The analysis results show that accelerators value market-related factors most. This means that startups that are subject to investment by accelerators are early-stage startups, and many companies have not fully developed their products or services. Therefore, market-related factors that can be evaluated objectively seem to be more important than products (or services) that are still ambiguous. Next, it was found that the factors related to the internal workforce of startups are more important. Since accelerators want to develop their businesses together with start-ups and team members through mentoring, ease of collaboration with them is very important, which seems to be important. The overall priority analysis results of the 26 investment determinants show that 'customer needs' and 'founders and team members' understanding of customers and markets' (0.62) are important and high priority factors. The results also show that startup accelerators consider the customer-centered perspective very important. And among the factors related to startups, the most prominent factor was the founder's openness and execution ability. Therefore, it can be confirmed that accelerators consider the ease of collaboration with these startups very important.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.111-132
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• 2022

The comprehensive examination on tendering system has been introduced to the Cultural Heritage repair and restoration field since 2016 to remedy the repair issues of South Gate in 2014. The Cultural Heritage Administration tried to attain the high performance of the cultural heritage repair and restoration works securing the proper payment for the repair and restoration works. It is high time to review the operating performance of the comprehensive examination on tendering system (hereinafter referred to as the "CEOTS"), as the system has been run for over 5 years to correspond with its original goal, i.e., "The Proper Payment in return for the High Performance of Repair and Restoration works." This study intends to analyze 114 tenders of CEOTS from 2016 to 2020. As a result of the analysis of 114 tenders, firstly, more than half of bid winners were in the top 20% of repair & restoration capacity disclosure amount list, which mostly fulfilled the goal of 'attaining high performance.' Secondly, as the winning bid rate is decreasing from 86.847% in 2017 to 85.488% in 2020, the goal of 'guarantee of a proper payment' is not achieved yet. Thirdly, the influence of Economic Evaluation section in CEOTS has been grown since the change of scoring system in CEOTS in 2019. This study identifies two reasons why the winning bid rate of CEOTS has decreased. Firstly, it is caused by the fact that 'the group that got more than 1st place' and 'the first place group' that are more than half of the total bidders have the decreasing bidding rate trend as the years go by. Secondly, the exclusion rate of 'the group that got more than 1st place' is higher than the exclusion rate of 'the group that got less than 1st place', which means the expected winning rate would be lowered. It is proposed that the revision of CEOTS code is needed, i.e. easing the strict rule concerning the exclusion rate as well as setting up the lower bidding limit to prevent the excessive decreasing winning bid rate.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.770-788
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• 2021

This study aimed to determine whether middle school students could understand global warming and the greenhouse effect, and explain them in terms of global radiative equilibrium. From July 13 to July 24 in 2021, 118 students in the third grade of middle school, who completed a class module on 'atmosphere and weather', participated in an online assessment consisting of multiple-choice and written answers on radiative equilibrium, the greenhouse effect, and global warming; 97 complete responses were obtained. After analysis, it was found that over half the students (61.9%) correctly described the meaning of radiative equilibrium; however, their explanations frequently contained prior knowledge or specific examples outside of the presented data. The majority of the students (92.8%) knew that the greenhouse effect occurs within Earth's atmosphere, but many (32.0%) thought of the greenhouse effect as a state in which the radiative equilibrium is broken. Less than half the students (47.4%) answered correctly that radiative equilibrium occurs on both Earth and the Moon. Most of the students (69.1%) understood that atmospheric re-radiation is the cause of the greenhouse effect, but few (39.2%) answered correctly that the amount of surface radiation emitted is greater than the amount of solar radiation absorbed by the Earth's surface. In addition, about half the students (49.5%) had a good understanding of the relationship between the increase in greenhouse gases and the absorption of atmospheric gases, and the resulting reradiation to the surface. However, when asked about greenhouse gases increases, their thoughts on surface emissions were very diverse; 14.4% said they increased, 9.3% said there was no change, 7.2% said they decreased, and 18.6% gave no response. Radiation equilibrium, the greenhouse effect, and global warming are a large semantic network connected by the balance and interaction of the Earth system. This can thus serve as a conceptual system for students to understand, apply, and interpret climate change caused by global warming. Therefore, with the current climate change crisis facing mankind, sophisticated program development and classroom experiences should be provided to encourage students to think scientifically and establish scientific concepts based on accurate understanding, with follow-up studies conducted to observe the effects.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.6
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• pp.49-63
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• 2021

The Forest Visitor Centers for Little Children who means preschoolers is an educational facility that achieves holistic growth by experiencing forests, and it should not be completed by installing specific facilities in the forest environment, but should be a space where preschoolers can play freely in the forest environment themselves. This study comprehensively evaluated the current status of Seoul Forest Visitor Centers for Little Children and suggested space improvement measures to enhance the effectiveness of forest experience. Through the theoretical review, seven spatial elements that enhance the effect of forest experience and six areas composing outdoor play areas were derived to prepare an analysis table for current status evaluation, and field survey studies were conducted on 24 centers in Seoul. Through expert interviews, the physical status was examined from the perspective of childhood education and the experiences of the users were summarized. As a result of the study, the Seoul Forest Visitor Center for Little Children is classified into six types according to the location characteristics and spatial structure, and has the characteristics of each type. The effectiveness of forest experience can be enhanced by identifying and revealing the environmental strengths of individual centers. In the case of outdoor experience learning zones, the proportion of exercise play areas was very large. By evenly organizing the forest experience space for each area, it will be possible to provide more diverse experiences to preschoolers. However, the status of uniform facility-oriented cannot be viewed as a fragmentary factor that lowers the effect of forest experience. The key to increasing the effect of forest experience by inducing creative activities is the spatial composition that considers the surrounding natural environment. Facilities should be a medium to help preschoolers' interest move into the forest. This study prepared data to understand the average physical status of the Seoul Forest Visitor Center for Little Children and suggested space improvement measures to increase the effectiveness of forest experience. This can be used as basic data for research to improve the quality level of the Seoul Forest Visitor Center for Little Children about 10 years after the project was implemented.

• Maritime Security
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• v.3 no.1
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• pp.141-185
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• 2021

The growing U.S.-China rivalry has placed the countries of Southeast Asia in exceedingly precarious positions. The Republic of Korea (ROK) likewise has been tasked with the challenge of "navigating the waters" between deepening geopolitical divides. It is in this context that the "New Southern Policy" (hereafter NSP) has become a key word in Korea's foreign policy circles. Through NSP, ROK aims to diversify its economic and security interests by strengthening ties with its southern partners, focusing on three key areas (termed as the "3 Ps"): People, Prosperity, and Peace. At the same time, the NSP seeks cooperation with other key diplomatic agendas such as the U.S.'s "Free and Open Indo-Pacific," rendering it crucial for the overall stability of the region. Considering such strategic significance, deeper analysis of the policy is more timely than ever. A brief assessment of the policy's outcome so far, however, reveals that relatively, the "Peace" pillar has been insufficient in achieving satisfactory outcomes. Here, this paper asks the question of: 1) How can the "Peace" pillar of South Korea's New Southern Policy be strengthened? Based on an analysis on the causes of the "Peace" pillar's weakness, this paper identifies counter-piracy cooperation as a solution. This paper then proceeds to answer the next question of: 2) How can ROK and ASEAN cooperate on counter-piracy, and how can these efforts be integrated into ROK's NSP? To answer the above question, this paper conducts in-depth case studies on ASEAN's and ROK's approaches to counter-piracy and identifies specific mechanisms of cooperation. In Chapter I, the paper begins with an overview of the NSP's strategic significance and an evaluation of its "Peace" pillar. Chapter II conducts a literature review on the causes of, and prescriptions for, the weakness of the "Peace" pillar. The paper then justifies why counter-piracy may be a solution. Chapter III examines ASEAN's and ROK's approaches to counter-piracy. By analyzing the general framework and each region's cases, the paper displays the strengths and weaknesses of each region's piracy responses. Based on this analysis, Chapter IV suggests ways to incorporate counter-piracy cooperation into the "Peace" pillar of the NSP. This research bears significance in that it identifies a specific area of cooperation (counter-piracy) to strengthen the "Peace" pillar of ROK's NSP. Such identification is based on a comprehensive study into the two parties' past and current experience in counter-piracy, making it contextual in nature. Furthermore, the study suggests practical mechanisms of cooperation, and considers ways of incorporation into the existing framework of NSP. This approach differs from existing literature that failed to generate case-specific, policy-oriented solutions. The COVID-19 pandemic has exacerbated piracy issues and deepened geopolitical divides. Turbulent seas such as these call for careful navigation. When it comes to promoting "peace," the key lies in combating the pirates that sail those very waters.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.15-24
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• 2021

This study is about the introduction and usefulness evaluation of the manufacturing method of the bolus-helmet. Helmet-production for the treatment of scalp tumor patients has been tried and will continue in many creative and various ways. However, Most of the research data did not significantly reduce the psychological burden and physical and physical discomfort that the patient had to bear due to the time and economic cost required for the production of the helmet, the convenience of production, and the complexity of the process. In addition, recently, studies using more advanced technologies and equipment such as 3D-printer technology, which are being studied as a way to increase the treatment effect, are being introduced, but the time, economic cost, and psychological and physical burden are still the sole responsibility of the patient. Isn't it getting worse? The reality is that the thoughts of concern cannot be erased. Therefore, by maintaining the physical properties of the bolus and manufacturing a helmet without incurring additional costs, the physical and physical discomfort aggravated to the patient was reduced and the procedure and time for helmet manufacturing were minimized. In this way, it was possible to reduce the time, economic cost, and physical discomfort required for the production of the helmet, and it was also possible to minimize the psychological burden of the patient, although it is invisible. Additionally, in evaluating the usefulness of helmets, we are able to continuously seek and develop ways to reduce the air-gap interval, and as a result, we will be able to introduce a method to keep it within 2.0mm along with the manufacturing method through this study. I feel very welcome. Finally, I hope that anyone working in the Department of Radiation Oncology will be able to easily manufacture the helmet required for radiation therapy using a bolus through the guide-line on helmet manufacturing provided by this institute. I hope and hope that if you have any questions or inquiries that arise during the production process, please feel free to contact us through the researcher's e-mail or mobile phone at any time.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.234-244
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• 2021

Purpose: To date, studies of firearm and explosive injuries in the Korean military have been limited compared to its importance. To overcome this, this study examined the characteristics of musculoskeletal damages in soldiers who have suffered firearm and explosive injuries over the past four years. Materials and Methods: From January 2015 to July 2019, military forces who had suffered musculoskeletal injuries from firearms or explosive substances were included. The medical records and radiographs were reviewed retrospectively, and telephone surveys about Short Musculoskeletal Functional Assessment (SMFA) for this group were conducted. To compare the functional outcomes, statistical analysis was performed using a t-test for the types of weapons, and ANOVA for others. Results: Of the 61 patients treated for firearms and explosives injuries, 30 patients (49.2%) were included after undergoing orthopedic treatment due to musculoskeletal injury. The average age at injury was 26.4 years old (21-52 years old). The number of officers and soldiers was similar. Eleven were injured by gunshot and 19 by an explosive device. Sixteen were treated in the Armed Forces Capital Hospital and 10 at private hospitals. More than half of the 16 patients (53.3%) with a fracture had multiple fractures. The most common injury site was the hand (33.3%), followed by the lower leg (30.0%). There were 14 patients (46.7%) with Gustilo-Anderson classification 3B or higher who required a soft tissue reconstruction. Fifteen patients agreed to join the SMFA survey for the functional outcomes. Between officers and soldiers, officers had better scores in the Bother Index compared to soldiers (p=0.0045). Patients treated in the Armed Forces Capital Hospital had better scores in both the Dysfunction and Bother Index compared to private hospitals (p=0.0008, p=0.0149). Conclusion: This is the first study to analyze of weapons injuries in the Korean military. As a result of the study, the orthopedic burden was high in the treating patients with military weapon injuries. In addition, it is necessary to build a military trauma registry, including firearm and explosive injuries, for trauma treatment evaluation and development of military trauma system.

• Journal of Korea Port Economic Association
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• v.37 no.4
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• pp.127-144
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• 2021

The purpose of this study is to derive service factors based on the "Rail Statistical Yearbook" data of railroad service providers from 1990 to 2019, and to analyze the effect of the service factors on the operating profit ratio(OPR), a representative management performance variable of railroad transport service providers. In particular, it has academic significance in terms of empirical research to evaluate whether the management innovation of the KoRail has changed in line with the purpose of establishing the corporation by dividing the research period into the first period (1990-2003) and the latter (2004-2019). The contents of this study investigated previous studies on the quality of railway passenger transportation service and analyzed the contents of government presentation data related to the management performance evaluation of the KoRail. As an empirical analysis model, a research model was constructed using OPR as a dependent variable and service factor variables of infrastructure, economy, safety, connectivity, and business diversity as explanatory variables based on the operation and management activity information during the analysis period 30 years. On the results of research analysis, OPR is that the infrastructure factor is improved by structural reform or efficiency improvement. And economic factors are the fact that operating profit ratio improves by reducing costs. The safety factor did not reveal the significant explanatory power of the regression coefficient, but the sign of influence was the same as the prediction. Connectivity factor reveals a influence on differences between first period and latter, but OPR impact direction is changed from negative in before to positive in late. This is an evironment in which connectivity is actually realized in later period. On diversity factor, there is no effect of investment share in subsidiaries and government subsidies on OPR.