• Journal of Intelligence and Information Systems
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• v.18 no.4
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• pp.19-42
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• 2012

Consumer consumption patterns are shifting rapidly as buyers migrate from offline markets to e-commerce routes, such as shopping channels on TV and internet shopping malls. In the offline markets consumers go shopping, see the shopping items, and choose from them. Recently consumers tend towards buying at shopping sites free from time and place. However, as e-commerce markets continue to expand, customers are complaining that it is becoming a bigger hassle to shop online. In the online shopping, shoppers have very limited information on the products. The delivered products can be different from what they have wanted. This case results to purchase cancellation. Because these things happen frequently, they are likely to refer to the consumer reviews and companies should be concerned about consumer's voice. E-commerce is a very important marketing tool for suppliers. It can recommend products to customers and connect them directly with suppliers with just a click of a button. The recommender system is being studied in various ways. Some of the more prominent ones include recommendation based on best-seller and demographics, contents filtering, and collaborative filtering. However, these systems all share two weaknesses : they cannot recommend products to consumers on a personal level, and they cannot recommend products to new consumers with no buying history. To fix these problems, we can use the information which has been collected from the questionnaires about their demographics and preference ratings. But, consumers feel these questionnaires are a burden and are unlikely to provide correct information. This study investigates combining collaborative filtering with the centrality of social network analysis. This centrality measure provides the information to infer the preference of new consumers from the shopping history of existing and previous ones. While the past researches had focused on the existing consumers with similar shopping patterns, this study tried to improve the accuracy of recommendation with all shopping information, which included not only similar shopping patterns but also dissimilar ones. Data used in this study, Movie Lens' data, was made by Group Lens research Project Team at University of Minnesota to recommend movies with a collaborative filtering technique. This data was built from the questionnaires of 943 respondents which gave the information on the preference ratings on 1,684 movies. Total data of 100,000 was organized by time, with initial data of 50,000 being existing customers and the latter 50,000 being new customers. The proposed recommender system consists of three systems : [+] group recommender system, [-] group recommender system, and integrated recommender system. [+] group recommender system looks at customers with similar buying patterns as 'neighbors', whereas [-] group recommender system looks at customers with opposite buying patterns as 'contraries'. Integrated recommender system uses both of the aforementioned recommender systems to recommend movies that both recommender systems pick. The study of three systems allows us to find the most suitable recommender system that will optimize accuracy and customer satisfaction. Our analysis showed that integrated recommender system is the best solution among the three systems studied, followed by [-] group recommended system and [+] group recommender system. This result conforms to the intuition that the accuracy of recommendation can be improved using all the relevant information. We provided contour maps and graphs to easily compare the accuracy of each recommender system. Although we saw improvement on accuracy with the integrated recommender system, we must remember that this research is based on static data with no live customers. In other words, consumers did not see the movies actually recommended from the system. Also, this recommendation system may not work well with products other than movies. Thus, it is important to note that recommendation systems need particular calibration for specific product/customer types.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.2
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• pp.33-41
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• 2019

Purpose: The purpose of this study is to improve the reduction of coverage of PTVs adjacent to organ at risk (OAR) by setting up overlapping Planning Target Volume (PTV) during Volumetric Modulated Arc Therapy(VMAT). Materials and Methods: In patients who received Whole Brain, Gall Bladder and Rectum radiation therapy, We compared the cover change, maximum dose, Homogenicity Index and Conformity Index of PTV and also compared the maximum dose and average dose change of Organ At Risk by organizing treatment plans that are not applied overlaped PTV and treatment plans that are applied overlaped PTV in areas where coverage is insufficient. Results: overage of treatment plans with overlapping PTVs was increased in all patients, and overall coverage was also increased in each of the four patients. The maximum dose for PTV was increased in five patients, and the Homogenicity Index and Conformity Index for all patients did not differ much. The maximum dose of the lens was increased by 1.12 times, and the maximum dose was decreased in two patients for brain stem. The mean dose of the eyeball was increased by a maximum of 1.15 times, and there was no significant difference between both parotid gland. In case of gallbladder cancer patients, the mean dose in the liver and colon was decreased, and the mean dose in the duodenum was increased. In the case of rectal cancer patients, the mean dose was reduced for both femur and bladder set as OARs. The overall MU was shown to be similar in four patients, excluding one. Conclusion: If the critical dose of OAR is considered and used properly, I think it is a useful way to improve coverage of PTV.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.57-68
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• 2017

Purpose: The purpose of this study was to compare volumetric modulated arc therapy(VMAT) with fixed-field intensity modulated radiation therapy(IMRT) using non-coplanar beam when the shape of target is irregular and the location is adjacent to organ at risk(OAR). Materials and Methods: The subjects of this study were a total of 6 patients who had radiation therapy for whole scalp(2 patients), partial scalp(2 patients), and whole ventricle(2 patients) by True Beam STX(Varian Medical Systems, USA). VMAT plans consisted of coplanar or non-coplanar arcs which can minimize the volume of OAR included in beamlets. All fixed-field IMRT plans consisted of non-coplanar beams using more than 2 angles of Couch. Results: The VMAT and IMRT plans were compared with regard to the maximum dose of both lens, both optic nerves, optic chiasm, and brain stem and the mean dose of both eyeballs and hippocampus. VMAT plans showed higher dose than ncIMRT plans at more than 6 of all OARs in every patient, and the ratio was from 1.1 times to 8.2 times. In case of total scalp and partial scalp, the volume of brain which received more than 20 Gy in the VMAT plans was 2 times larger than the volume in the ncIMRT plans. In case of whole ventricle, there was no significant difference. Target coverage was satisfied in both plans($PTV_{100%}=95%$). The maximum dose in target volume and required monitor unit(MU) of ncIMRT were higher than them of VMAT plans. Conclusion: Even though ncIMRT is less efficient than VMAT with regard to required MU and treatment time, the dose to OARs is much lower than VMAT and PTV Coverage is similar with VMAT. If the shape of target is irregular and location is adjacent to OAR, comparison VMAT plan with ncIMRT plan deserves to be considered.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.463-469
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• 2015

Purpose: A hydrogel including alginate and $CaCl_2$ extracted from seaweed was manufactured, and their physical properties were investigated. Also, its applicability as contact lenses was examined. Methods: A film-type sample used in this experiment was manufactured using 2-hydroxyethyl methacrylate (HEMA), which is the raw material of hydrogel contact lenses; azobisiobutyonitile (AIBN), which is an initiator and ethylenglycoldimethacrylate (EGDMA), which is a cross-linking agent. It was hydrated in a PBS solution for 24 hours, and an interpenetrating polymer network (IPN) was formed in 1% and 2% alginate and 1%, 3%, and 5% $CaCl_2$ solutions for 24 hours, respectively. Results: The measurement of the physical properties of the film after the IPN showed that the moisture content was 30.89~36.89%, the refractive index was 1.431~1.441, the contact angle was $62.98{\sim}80.45^{\circ}$, and the tensile strength was 2.378~4.215 ($gf/mm^2$). Also, the physical properties hardly changed as the content of alginate increased, and the moisture content decreased as the content of $CaCl_2$ increased. As a result of the IPN, the moisture content and contact angle decreased compared to those of basic HEMA, but the tensile strength increased. The tensile strength of the second IPN was higher than that of the first IPN. In the case of $CaCl_2$, for the sample polymerized for 24 hours and the second IPN sample with 2% alginate, the contact angle decreased as the content of $CaCl_2$ increased. Conclusions: In this study, the tensile strength increased as the content of $CaCl_2$ increased, and the wettability increased as a result of IPN of alginate and $CaCl_2$. The hydrogel containing the alginate and $CaCl_2$ was confirmed possible utilization as contact lens material.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.509-516
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• 2016

A dental panoramic radiography which usually uses low level X-rays is subject to the Nuclear Safety Act when it is installed for the purpose of education. This paper measures radiation dose and spatial dose rate by usage and thereby aims to verify the effectiveness of radiation safety equipment and provide basic information for radiation safety of radiation workers and students. After glass dosimeter (GD-352M) is attached to direct exposure area, the teeth, and indirect exposure area, the eye lens and the thyroid, on the dental radiography head phantom, these exposure areas are measured. Then, after dividing the horizontal into a $45^{\circ}$, it is separated into seven directions which all includes 30, 60, 90, 120 cm distance. The paper shows that the spatial dose rate is the highest at 30 cm and declines as the distance increases. At 30 cm, the spatial dose rate around the starting area of rotation is $3,840{\mu}Sv/h$, which is four times higher than the lowest level $778{\mu}Sv/h$. Furthermore, the spatial dose rate was $408{\mu}Sv/h$ on average at the distance of 60 cm where radiation workers can be located. From a conservative point of view, It is possible to avoid needless exposure to radiation for the purpose of education. However, in case that an unintended exposure to radiation happens within a radiation controlled area, it is still necessary to educate radiation safety. But according to the current Medical Service Act, in medical institutions, even if they are not installed, the equipment such as interlock are obliged by the Nuclear Safety Law, considering that the spatial dose rate of the educational dental panoramic radiography room is low. It seems to be excessive regulation.

• Anatomy & Biological Anthropology
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• v.31 no.4
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• pp.133-142
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• 2018

3D histology is a imaging system for the 3D structural information of cells or tissues. The synchrotron radiation propagation phase contrast micro-CT has been used in 3D imaging methods. However, the simple phase contrast micro-CT did not give sufficient micro-structural information when the specimen contains soft elements, as is the case with many biomedical tissue samples. The purpose of this study is to develop a new technique to enhance the phase contrast effect for soft tissue imaging. Experiments were performed at the imaging beam lines of Pohang Accelerator Laboratory (PAL). The biomedical tissue samples under frozen state was mounted on a computer-controlled precision stage and rotated in $0.18^{\circ}$ increments through $180^{\circ}$. An X-ray shadow of a specimen was converted into a visual image on the surface of a CdWO4 scintillator that was magnified using a microscopic objective lens(X5 or X20) before being captured with a digital CCD camera. 3-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed were performed using Amira software. In this study, We found that synchrotron phase contrast imaging of frozen tissue samples has higher contrast power for soft tissue than that of non-frozen samples. In conclusion, synchrotron radiation propagation phase contrast cryo-microCT imaging offers a promising tool for non-destructive high resolution 3D histology.

• Journal of Technology Innovation
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• v.26 no.4
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• pp.199-232
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• 2018

There are increasing needs for understanding and fathoming of business management environment through big data analysis at industrial and corporative level. The research using the company disclosure information, which is comprehensively covering the business performance and the future plan of the company, is getting attention. However, there is limited research on developing applicable analytical models leveraging such corporate disclosure data due to its unstructured nature. This study proposes a text-mining-based analytical model for industrial and firm level analyses using publicly available company disclousre data. Specifically, we apply LDA topic model and word2vec word embedding model on the U.S. SEC data from the publicly listed firms and analyze the trends of business topics at the industrial and corporate levels. Using LDA topic modeling based on SEC EDGAR 10-K document, whole industrial management topics are figured out. For comparison of different pattern of industries' topic trend, software and hardware industries are compared in recent 20 years. Also, the changes of management subject at firm level are observed with comparison of two companies in software industry. The changes of topic trends provides lens for identifying decreasing and growing management subjects at industrial and firm level. Mapping companies and products(or services) based on dimension reduction after using word2vec word embedding model and principal component analysis of 10-K document at firm level in software industry, companies and products(services) that have similar management subjects are identified and also their changes in decades. For suggesting methodology to develop analysis model based on public management data at industrial and corporate level, there may be contributions in terms of making ground of practical methodology to identifying changes of managements subjects. However, there are required further researches to provide microscopic analytical model with regard to relation of technology management strategy between management performance in case of related to various pattern of management topics as of frequent changes of management subject or their momentum. Also more studies are needed for developing competitive context analysis model with product(service)-portfolios between firms.

• Journal of The Korean Association For Science Education
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• v.41 no.3
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• pp.237-250
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• 2021

Teachers play a key role in designing a students' learning experience. Teachers are asked to interpret the context in which they are located and to adjust their practice to fit circumstantial needs based on their teacher agency. In this study, we explore the emergence of teacher agency in distance learning caused by COVID-19 and we analyze factors shaping the teacher agency. For this purpose, we interviewed six secondary science teachers who practiced distance learning in 2020. Semi-constructed interviews and their artifacts were collected and analyzed. This study shows that teacher agency is captured when they respond to circumstantial change and modify their practice to achieve their professional purpose or adjust their practice in space for maneuvering or keep their practice consistent. This study also analyzes the factors that affect the emergence of teacher agency in two dimensions. One is individual and the other is contextual. In the individual dimension, educational values shaped by his/her experiences and short/long-term goals for the future support the emergence of teacher agency. In the contextual dimension, there are collaborative and flexible culture shared by the community, co-operation within the teacher community, and material support. On the other hand, in the individual dimension, the teachers' sense of their role, and no reflection for own practice constrain the emergence of teacher agency, and in the contextual dimension, performativity discourse and strong requirement without guidance constrain the emergence of teacher agency. We suggest an effective lens for establishing a strategy that support teachers' professional practice and the emergence of teacher agency.

• Journal of the Daesoon Academy of Sciences
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• v.35
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• pp.39-71
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• 2020

Ever since gaining liberation in 1945, Korean society has constantly recalled memories of Japan's invasion and Korea's anti-Japanese movements for an independent state (AMIS). In the process, a small number of new religious groups were also identified as main subjects within AMIS. However, the logic necessary to connect these religious groups with AMIS was still weak. In order to solve this situation academically, the purpose of this article is to illuminate the activities of Mugeukdo (無極道) and Jo Jeongsan (趙鼎山) through the lens of AMIS and to reflect on the issues that will arise when linking the religion with AMIS. Regarding this purpose, this article analyzed the internal and external data collected by Daesoon Jinrihoe (大巡眞理會) about Jo Jeongsan and Mugeukdo's activities linked to AMIS. Later, this paper presents several tasks for future research on this subject matter. Specifically, according to Chapter II, the AMIS of Jo Jeongsan and Mugeukdo were generally centered on resistance at the family level, Jo Jeongsan's order to participate in the March 1st Movement, and Mugeukdo's industrial activities. In Chapter III, I reviewed the contents of Chapter II using Daesoon Jinrihoe's external materials. According to the results of the review, future research is required to discover and cross-check materials related to the AMIS of Jo Jeongsan and Mugeukdo believers. Likewise, further research is needed to highlight the theory of the enthronement of emperor (天子登極說) and the Great Opening of the later world (後天開闢) in terms of AMIS. These efforts can make contributions that increase the credibility of Daesoon Jinrihoe's internal data on the AMIS of Jo Jeongsan and Mugeukdo and expand the periphery of AMIS as it relates to certain religious groups. Subsequently, in Chapter IV, I present three items for reflecting upon the connection between certain religious groups and AMIS. The first is that criteria for establishing the category of AMIS is necessary to determine whether religious activities can be included. Second, reductionist approaches make it difficult to explain the reasons why some of the people who participated in AMIS did so while forming 'new religious movements,' and why these groups have maintained their religious identity even after liberation was achieved in 1945. Third, it is necessary to distinguish between the primary and the secondary dimensions to elaborate on the connection between these religions and AMIS. This means that researchers should be expected to look at whether the activities in question are based on a religious worldview and whether the goal of the activities is the realization of AMIS or the implementation of some aspect of that religious worldview. In the future, considering the mechanisms that make AMIS memorable in Korea, religious groups and religious studies should take greater interest in discovering and accumulating data that facilitates research on these topics. At the same time, effort should be made to find the basis for AMIS within religious worldviews. It can also be made possible through specific interest in further elaboration on the various AMIS-related activities of Jo Jeongsan and Mugeukdo.

• Korean Journal of Social Welfare Studies
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• v.42 no.4
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• pp.239-262
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• 2011

The Korean government's recent large-scale termination and modification of welfare benefits revealed a procedural problem under the National Basic Living Security Act. Under the Act, welfare recipients have a legal right to make complaints only after the termination or modification is enforced; the Act fails to provide the recipients with an opportunity for a hearing before termination or modification, and this creates serious threats to the recipients, whose livelihoods are dependent on welfare benefits. Korean jurisprudence has adopted the due process of law principle. The principle originated from the due process in US jurisprudence, and Korea has applied it broadly to any government actions that restrict individuals' constitutional or legal rights. This paper reviews the termination or modification procedure under the Act with the lens of the due process principle and criticizes that the current law is not in compliance with the principle. In supporting that such termination and modification procedure infringes on welfare recipients' protected rights, this paper discusses two theories as to what rights are protected. First, termination or modification of welfare benefits can be considered as deprivation of property. The 'property' theory may be weak under Korean jurisprudence, because the concept of property under the Korean Constitution is narrowly construed. Second, this paper relies on the constitutional provision that recognizes "the right to a life worthy of human beings," which requires the State to guarantee minimum standard of living for all. As welfare recipients are deemed to receive benefits as a right under the Constitution, any deviation from the minimum requirement would constitute a violation of constitutional rights. In any case, termination or modification of welfare benefits that are concretized under the Act should be protected under the due process principle, because the principle would cover any government actions that restrict established legal rights. This paper argues that the procedural due process requires the recipients be guaranteed an opportunity to have a hearing before the termination or modification is enforced. An independent decision-maker should hear the proceedings, and the recipients should have an option to orally present their opinions in front of the decision-maker. The hearing process under the Administrative Procedures Act of Korea offers elements that would satisfy these procedural requirements. Thus, this paper concludes that the National Basic Living Security Act should be amended to adopt the hearing process under the Administrative Procedures Act in its termination and modification procedure.