• Journal of Intelligence and Information Systems
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• v.25 no.3
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• pp.19-41
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• 2019

According to the rapidly increasing demand for text data analysis, research and investment in text mining are being actively conducted not only in academia but also in various industries. Text mining is generally conducted in two steps. In the first step, the text of the collected document is tokenized and structured to convert the original document into a computer-readable form. In the second step, tasks such as document classification, clustering, and topic modeling are conducted according to the purpose of analysis. Until recently, text mining-related studies have been focused on the application of the second steps, such as document classification, clustering, and topic modeling. However, with the discovery that the text structuring process substantially influences the quality of the analysis results, various embedding methods have actively been studied to improve the quality of analysis results by preserving the meaning of words and documents in the process of representing text data as vectors. Unlike structured data, which can be directly applied to a variety of operations and traditional analysis techniques, Unstructured text should be preceded by a structuring task that transforms the original document into a form that the computer can understand before analysis. It is called "Embedding" that arbitrary objects are mapped to a specific dimension space while maintaining algebraic properties for structuring the text data. Recently, attempts have been made to embed not only words but also sentences, paragraphs, and entire documents in various aspects. Particularly, with the demand for analysis of document embedding increases rapidly, many algorithms have been developed to support it. Among them, doc2Vec which extends word2Vec and embeds each document into one vector is most widely used. However, the traditional document embedding method represented by doc2Vec generates a vector for each document using the whole corpus included in the document. This causes a limit that the document vector is affected by not only core words but also miscellaneous words. Additionally, the traditional document embedding schemes usually map each document into a single corresponding vector. Therefore, it is difficult to represent a complex document with multiple subjects into a single vector accurately using the traditional approach. In this paper, we propose a new multi-vector document embedding method to overcome these limitations of the traditional document embedding methods. This study targets documents that explicitly separate body content and keywords. In the case of a document without keywords, this method can be applied after extract keywords through various analysis methods. However, since this is not the core subject of the proposed method, we introduce the process of applying the proposed method to documents that predefine keywords in the text. The proposed method consists of (1) Parsing, (2) Word Embedding, (3) Keyword Vector Extraction, (4) Keyword Clustering, and (5) Multiple-Vector Generation. The specific process is as follows. all text in a document is tokenized and each token is represented as a vector having N-dimensional real value through word embedding. After that, to overcome the limitations of the traditional document embedding method that is affected by not only the core word but also the miscellaneous words, vectors corresponding to the keywords of each document are extracted and make up sets of keyword vector for each document. Next, clustering is conducted on a set of keywords for each document to identify multiple subjects included in the document. Finally, a Multi-vector is generated from vectors of keywords constituting each cluster. The experiments for 3.147 academic papers revealed that the single vector-based traditional approach cannot properly map complex documents because of interference among subjects in each vector. With the proposed multi-vector based method, we ascertained that complex documents can be vectorized more accurately by eliminating the interference among subjects.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.23-33
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• 2021

In Korea, many reservoirs have been built for the purpose of solving the food shortage problem and supplying agricultural water. However, the current 75.6% of the reservoirs are in serious aged as more than 50 years have passed since the year of construction. In the case of such an aging reservoir, the stability due to scour and erosion inside the reservoir is very reduced, and if concentrated rainfall due to recent abnormal weather occurs, the aging reservoir may collapse, leading to a lot of damage to property and human life. Accordingly, each agency that manages aging reservoirs uses Ordinary Portland Cement (OPC) as an injection material and applies the grouting method. However, in the case of OPC, it may deteriorate over time and water leakage may occur again. And there are environmental problems such as consumption of natural resources and generation of greenhouse gases. So, there is a need to develop new materials and methods that can replace the OPC. In this study, an laboratory test and analysis were performed on the grout material developed to induce a curing reaction similar to that of OPC by recycling power plant byproduct. In addition, test in the field such as electric resistivity survey, Standard Penetration Test (SPT), and field permeability test were performed to analyzed to reinforcement effect and determine the possibility of using instead of OPC. As a results of the test, in the case of recycled power plant byproduct, the compressive strength was 2.9 to 3.2 times and the deformation modulus was 2.3 to 3.3 times higher, indicating that it is excellent in strength and can be used instead of OPC. And it was analyzed that the N value of the reservoir was increased by 1~2, and the coefficient of permeability (k) decreased to the level of 8.9~42.5%. showing sufficient reinforcing effect in terms of order.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.65-75
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• 2021

Coin cell is a basic testing platform for battery research, discovering new materials and concepts, and contributing to fundamental research on next-generation batteries. Li metal batteries (LMBs) are promising since a high energy density (~500 Wh kg^-1) is deliverable far beyond Li-ion. However, Li dendrite-triggered volume fluctuation and high surface cause severe deterioration of performance. Given that such drawbacks are strongly dependent on the cell parameters and structure, such as the amount of electrolyte, Li thickness, and internal pressure, reliable Li metal coin cell testing is challenging. For the LMB-specialized coin cell testing platform, this study suggests the optimal coin cell structure that secures performance and reproducibility of LMBs under stringent conditions, such as lean electrolyte, high mass loading of NMC cathode, and thinner Li use. By controlling the cathode/anode (C/A) area ratio closer to 1.0, the inactive space was minimized, mitigating the cell degradation. The quantification and imaging of inner cell pressure elucidated that the uniformity of the pressure is a crucial matter to improving performance reliability. The LMB coin cells exhibit better cycling retention and reproducibility under higher (0.6 MPa → 2.13 MPa) and uniform (standard deviation: 0.43 → 0.16) stack pressure through the changes in internal parts and introducing a flexible polymer (PDMS) film.

• (The)Study of the Eastern Classic
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• no.48
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• pp.253-287
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• 2012

This research aimed to discuss the necessity of education and evil through perspective of Sunja and Hannah Arendt. In case of Sunja, it was reviewed by his opinion about Sunja as the central figure. As for Arendt, it was researched with "Eichmann in Jerusalem" as the central figure which she wrote participating in the trial process of Eichmann who was a war criminal of Nazi. Sunja thought evil as the nature of people and understood that they all are originally selfish, envious, and seeking desire. Therefore, Sunja thought it is important to properly seek human desire. He claimed Haw Seong Gi Wi(化性起僞, changing evil human nature into goodness through manner) which changes human nature from evil to goodness. A teacher who leads evil into goodness is surely needed in the process of Haw Seong Gi Wi. At the same time, in the dimension of educational content it put stress on the role of Ye(禮, manner) which lets them realize discernment so that they properly seek human desire and Ak(樂, harmony) which harmoniously controls human emotion, and key point on education regarding Ye and Ak. As for Arendt, however, she recognized evil as normal one. Even though he thought that conforming the order of superior authority was the best value and then took evil of killing many Jews in thoughtlessness, Eichmann maintained that he did not take evil but only conformed the order. This way, people could take evil in thoughtlessness in totalitarianism, and it makes circumstance that they could not take goodness. Therefore they could take evil in thoughtlessness and experience the radical evil and the banality of evil. Accordingly, political praxis which guarantees people's plurality as the words and praxis is needed. It is named natality because the truth that they are born in this world is a starting point, and makes the essence of education. In this process, teachers have to be a representative of this generation for children as new social members, and be able to keep children's newness. Sunja and Arendt have the same equality and difference in that they referred to the necessity of education to overcome human evil. It is the same quality that goodness could recover the function of community and the practice of education is considered important in the goal of education and the dimension of directivity. It is different in methodical characteristic of education that Arendt, however, suggests praxis as the way that they express themselves in totalitarianism while Sunja thought that continuous practice piling up virtue for goodness is important.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.83-89
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• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.

• Clean Technology
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• v.27 no.1
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• pp.1-8
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• 2021

Due to the negative impacts of microplastics (MPs) on the ecosystem, the investigation of its occurrence and its treatment from sewage and wastewater treatment plants (WWTPs) have received a lot of attention in the recent years. Most MPs are precipitated and removed with the sludge during the treatment process. Proper sludge management is immensely necessary to avoid MP exposure in the environment. However, the domestic research on this aspect is limited. This study reviews appropriate sludge management approaches to decrease environmental MP exposure. This can be achieved through investigating sludge generation and treatment, regulation laws and government policy trends with an emphasis on WWTPs. The ratio of sludge in sewage treatment plants has been observed to be highest in recycling followed by incineration and landfills. Recycling is the highest in fuel followed by construction materials and composting. For WWTPs, the highest ratio is in recycling followed by fuel and landfills, and recycling is confirmed in the following order: incineration > after composting > after solidification > earthworm breeding. Treatment approaches that can increase the exposure of MPs to the ecosystem are considered to be used in landfills and agricultural fields. However, this method is not appropriate given the insufficient capacity of domestic landfills and the sufficient supply of existing chemical and animal manure fertilizers. Instead, it would be rational in terms of environmental preservation to expand the use of fuel and energy in connection with the new and renewable energy policy, and to actively seek the use of sub-materials for construction materials. In order to secure the basic data for the effectiveness of future planning and revision of related laws, it is required to perform an in-depth investigation of the sludge supply and demand status along with the environmental and economic effects.

• Journal of Science Education
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• v.45 no.3
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• pp.292-303
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• 2021

This study identifies the terms frequently used together with energy in online science news articles and topics of the news reports to find out how the term energy is used in everyday life and to draw implications for science curriculum and instruction about energy. A total of 2,171 online news articles in science category published by 11 major newspaper companies in Korea for one year from March 1, 2018 were selected by using energy as a search term. As a result of natural language processing, a total of 51,224 sentences consisting of 507,901 words were compiled for analysis. Using the R program, term frequency analysis, semantic network analysis, and structural topic modeling were performed. The results show that the terms with exceptionally high frequencies were technology, research, and development, which reflected the characteristics of news articles that report new findings. On the other hand, terms used more than once per two articles were industry-related terms (industry, product, system, production, market) and terms that were sufficiently expected as energy-related terms such as 'electricity' and 'environment.' Meanwhile, 'sun', 'heat', 'temperature', and 'power generation', which are frequently used in energy-related science classes, also appeared as terms belonging to the highest frequency. From a network analysis, two clusters were found including terms related to industry and technology and terms related to basic science and research. From the analysis of terms paired with energy, it was also found that terms related to the use of energy such as 'energy efficiency,' 'energy saving,' and 'energy consumption' were the most frequently used. Out of 16 topics found, four contexts of energy were drawn including 'high-tech industry,' 'industry,' 'basic science,' and 'environment and health.' The results suggest that the introduction of the concept of energy degradation as a starting point for energy classes can be effective. It also shows the need to introduce high-tech industries or the context of environment and health into energy learning.

• Journal of Popular Narrative
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• v.26 no.1
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• pp.135-174
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• 2020

The article focuses on the student activism experience of the 1990s and 2010s and on the accumulation of everyday experiences created by the conditions of the 2010s against the backdrop of differences in how the composition of 'we' is portrayed in oral narrative. What stands out in the 90s oral narratives on student activism experiences, which were compiled in the 2010s, is the distancing of the culture of student activism at that time. In the words of speakers who experienced university life in the 1990s, the culture of student activism at the university was created through private relationships, and was, needless to say, considered 'natural'. At the same time, however, the 'natural' is said to be 'abnormal' or 'strange' in the context of the 2010s in which it is being talked about, and is meant to be an experience with a certain distance from the present speakers. This aspect is associated with the conditions under which the experience of the 90s is being described in the 2010s. The present, which explains past experiences to speakers, was explained after the 2016 candlelight protest and Gangnam Station femicide protest, and is described as a world that is qualitatively different from before, and is located as an opportunity to create a critical distance from past experiences. This qualitative change, which raises suspicions about the homogenous "we", is based on a newly acquired sense of gender sensitivity, living since the mid-2010s, when gentler issues were the biggest topic in Korean society, among others. In the 2010s, the composition of 'we' is no longer understood as a community of people who share any commonality, but as individuals who unite despite numerous differences. This reveals the experiences of those who have already embodied this in their everyday senses in the 2010s. The 'we' they formed should have nothing to do with private relationships, nor was homogeneity considered the most prominent group, so it was nothing that could explain the 'me' at the time of the demonstration and outside of the venue. It was in that context that the relevant experience was described in a cautious manner throughout. This, in turn, raises the need to ask and understand a new sense of student activism and, moreover, social movements and the sense of unity as 'we'. It should also be asked who is the main body of the movement and what is the use of asking it. Soon, the need and meaning of defining the fixed identity of 'we' in the movement should be questioned. Therefore, it should be asked what fixed positions or coordinates can really represent someone's position.

• Korean Association of Arts Management
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• no.58
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• pp.5-47
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• 2021

This paper is a story about five middle-aged men in their 50s who suddenly began their photographic activities as they reached middle age. In the perspective of Borudieu's cultural capital theory, this study observes five men in their 50s by implementing in-depth interviews about the motivation behind taking photographs, the experience of photography activities, and the rewards of these activities. The theory has undergone a theoretical revision with the criticism that factors other than the class can be influential. Based on these ideas, I have proceeded my study by preferentially grasping the notion of the 'field' in accordance with the specific history of Korean society. Therefore, this study sought to more specifically understand the various photographic activities of middle-class men in their 50s by referring Coskuner-Balli and Thompson's argument(2013), which revised 2018's cultural captial theory and proposed the concept of 'subordinate cultural capital' and 'leisure capital' who proposed by Backlund, E. A. & Kuentzel, W. F.(2013). As a middle-class men in their 50s, research participants have grown up and worked in a social atmosphere where economic capital is recognized as an individual's ability. However, they are faced with the value that the knowledge and taste towards culture and arts is one's identity. In addition to the subjective deprivation that arises from this situation, the lifespan characteristic of their age that it is on the brink of the old age appeared to have influenced them to put their psychological motivation immediately into practice. Economic capital was the main conversion terms to move form interest to practice, which includes 'time' as a resource as well as money. With the cultural practices being expanded since their creation of photographs, the reason that these expansions can be maintained more actively lies in their identity as 'cultural artist' that is consolidated in new relationships in the sharing of photographic activities. In this way, photographic activities grant a symbolic status of 'a middle-aged man who actively builds and expresses his identity' through the conversion of accumulating cultural capital and the conversion into social capital. Furthermore, the recognized scope of the symbolic capital acquired by the research participants is in the domain of the private life that is family and acquaintance. Especially, they were gaining a great psychological reward from their children's recognition that they are not just a 'breadwinner' but 'dad who cultivates himself with a culture and arts'. Accordingly, by considering that 'generation' other than class can be a meaningful discussion point when understanding Korea society from the perspective of cultural theory, this study is meaningful that a more flexible understanding of cultural theory can give a glimpse into the possibility of a more specific and diverse approach that will arise in the discussion of culture and arts education.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.4
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• pp.67-76
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• 2021

Biogasification is a technology that produces environmentally friendly fuel using methane gas generated in the process of stably decomposing and processing organic waste. Biogasification is the most used method for energy conversion of organic waste with high moisture content, and is a useful method for organic waste treatment following the prohibition of direct landfill (2005) and marine dumping (2013). Due to African Swine Fever (ASF), which recently occurred in Korea, recycling of wet feed is prohibited, and consumers such as dry feed and compost are negatively recognized, making it difficult to treat food waste. Accordingly, biogasification is attracting more attention for the treatment and recycling of food waste. Korea's energy consumption amounted to 268.41 106toe, ranking 9th in the world. However, it is an energy-poor country that depends on foreign imports for about 95.8% of its energy supply. Therefore, in Korea, the Renewable Energy Portfolio Standard (RPS) is being introduced. The domestic RPS system sets the weight of the new and renewable energy certificate (REC, Renewable energy certificate) of waste energy lower than that of other renewable energy. Therefore, an additional incentive system is required for the activation of waste-to-energy. In this study, the operation of an anaerobic digester that treats food waste, food waste Leachate and various organic wastes was confirmed. It was intended to be used as basic data for preparing the waste-to-energy incentive system through precise monitoring for a certain period of time. Four sites that produce biogas from organic waste and use them for power generation and heavy gas were selected as target facilities, and field surveys and sampling were conducted. Basic properties analysis was performed on the influent sample of organic waste and the effluent sample according to the treatment process. As a result of the analysis of the properties, the total solids of the digester influent was an average of 12.11%, and the volatile solids of the total solids were confirmed to be 85.86%. BOD and CODcr removal rates were 60.8% and 64.8%. The volatile fatty acids in the influent averaged 55,716 mg/L. It can be confirmed that most of the volatile fatty acids were decomposed and removed with an average reduction rate of 92.3% after anaerobic digestion.