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Predicting the Performance of Recommender Systems through Social Network Analysis and Artificial Neural Network (사회연결망분석과 인공신경망을 이용한 추천시스템 성능 예측)

  • Cho, Yoon-Ho;Kim, In-Hwan
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.159-172
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    • 2010
  • The recommender system is one of the possible solutions to assist customers in finding the items they would like to purchase. To date, a variety of recommendation techniques have been developed. One of the most successful recommendation techniques is Collaborative Filtering (CF) that has been used in a number of different applications such as recommending Web pages, movies, music, articles and products. CF identifies customers whose tastes are similar to those of a given customer, and recommends items those customers have liked in the past. Numerous CF algorithms have been developed to increase the performance of recommender systems. Broadly, there are memory-based CF algorithms, model-based CF algorithms, and hybrid CF algorithms which combine CF with content-based techniques or other recommender systems. While many researchers have focused their efforts in improving CF performance, the theoretical justification of CF algorithms is lacking. That is, we do not know many things about how CF is done. Furthermore, the relative performances of CF algorithms are known to be domain and data dependent. It is very time-consuming and expensive to implement and launce a CF recommender system, and also the system unsuited for the given domain provides customers with poor quality recommendations that make them easily annoyed. Therefore, predicting the performances of CF algorithms in advance is practically important and needed. In this study, we propose an efficient approach to predict the performance of CF. Social Network Analysis (SNA) and Artificial Neural Network (ANN) are applied to develop our prediction model. CF can be modeled as a social network in which customers are nodes and purchase relationships between customers are links. SNA facilitates an exploration of the topological properties of the network structure that are implicit in data for CF recommendations. An ANN model is developed through an analysis of network topology, such as network density, inclusiveness, clustering coefficient, network centralization, and Krackhardt's efficiency. While network density, expressed as a proportion of the maximum possible number of links, captures the density of the whole network, the clustering coefficient captures the degree to which the overall network contains localized pockets of dense connectivity. Inclusiveness refers to the number of nodes which are included within the various connected parts of the social network. Centralization reflects the extent to which connections are concentrated in a small number of nodes rather than distributed equally among all nodes. Krackhardt's efficiency characterizes how dense the social network is beyond that barely needed to keep the social group even indirectly connected to one another. We use these social network measures as input variables of the ANN model. As an output variable, we use the recommendation accuracy measured by F1-measure. In order to evaluate the effectiveness of the ANN model, sales transaction data from H department store, one of the well-known department stores in Korea, was used. Total 396 experimental samples were gathered, and we used 40%, 40%, and 20% of them, for training, test, and validation, respectively. The 5-fold cross validation was also conducted to enhance the reliability of our experiments. The input variable measuring process consists of following three steps; analysis of customer similarities, construction of a social network, and analysis of social network patterns. We used Net Miner 3 and UCINET 6.0 for SNA, and Clementine 11.1 for ANN modeling. The experiments reported that the ANN model has 92.61% estimated accuracy and 0.0049 RMSE. Thus, we can know that our prediction model helps decide whether CF is useful for a given application with certain data characteristics.

Effect of Cognitive Affordance of Interactive Media Art Content on the Interaction and Interest of Audience (인터랙티브 미디어아트 콘텐츠의 인지적 어포던스가 관람자의 인터랙션과 흥미에 미치는 영향)

  • Lee, Gangso;Choi, Yoo-Joo
    • KIPS Transactions on Software and Data Engineering
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    • v.5 no.9
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    • pp.441-450
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    • 2016
  • In this study, we investigate the effect of the level of cognitive affordance which explains an explicit interaction method on the interest of viewers. Viewer's recognition of the interaction method is associated with cognitive affordance as a matter of visual-perceptual exposure of the input device and viewer's cognition of it. The final goal of the research on affordance is to enhance the audience participation rather than the smooth interation. Many interactive media artworks have been designed with hiding the explicit explanation to the artwork due to worry that the explicit explanation may also hinder the induction of impressions leading the viewer to an aesthetic experience and the retainment of interest. In this context, we set up two hypotheses for study on cognitive affordance. First, the more explicit the explanation of interaction method is, the higher the viewer' understanding of interaction method is. Second, the more explicit the explanation of interaction method is, the lower the interest of the viewer is. An interactive media art work was manufactured with three versions which vary in the degree of visual-perceptual information suggestion and we analyzed the participation and interest level of audience in each version. As a result of the experiments, the version with high explicitness of interaction was found to have long time spent on watching and high participation and interest of viewers. On the contrary, the version with an unexplicit interaction method was found to have low interest and satisfaction of viewers. Therefore, regarding usability, the hypothesis that a more explicit explanation of interaction would lower the curiosity and interest in exploration of the viewer was dismissed. It was confirmed that improvement of cognitive affordance raised the interaction of the work of art and interest of the viewer in the proposed interactive content. This study implies that interactive media art work should be designed in view of that the interaction and interest of audience can be lowered when cognitive affordance is low.

The Feasibility Study of MRI-based Radiotherapy Treatment Planning Using Look Up Table (Look Up Table을 이용한 자기공명영상 기반 방사선 치료계획의 타당성 분석 연구)

  • Kim, Shin-Wook;Shin, Hun-Joo;Lee, Young-Kyu;Seo, Jae-Hyuk;Lee, Gi-Woong;Park, Hyeong-Wook;Lee, Jae-Choon;Kim, Ae-Ran;Kim, Ji-Na;Kim, Myong-Ho;Kay, Chul-Seung;Jang, Hong-Seok;Kang, Young-Nam
    • Progress in Medical Physics
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    • v.24 no.4
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    • pp.237-242
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    • 2013
  • In the intracranial regions, an accurate delineation of the target volume has been difficult with only the CT data due to poor soft tissue contrast of CT images. Therefore, the magnetic resonance images (MRI) for the delineation of the target volumes were widely used. To calculate dose distributions with MRI-based RTP, the electron density (ED) mapping concept from the diagnostic CT images and the pseudo CT concept from the MRI were introduced. In this study, the look up table (LUT) from the fifteen patients' diagnostic brain MRI images was created to verify the feasibility of MRI-based RTP. The dose distributions from the MRI-based calculations were compared to the original CT-based calculation. One MRI set has ED information from LUT (lMRI). Another set was generated with voxel values assigned with a homogeneous density of water (wMRI). A simple plan with a single anterior 6MV one portal was applied to the CT, lMRI, and wMRI. Depending on the patient's target geometry for the 3D conformal plan, 6MV photon beams and from two to five gantry portals were used. The differences of the dose distribution and DVH between the lMRI based and CT-based plan were smaller than the wMRI-based plan. The dose difference of wMRI vs. lMRI was measured as 91 cGy vs. 57 cGy at maximum dose, 74 cGt vs. 42 cGy at mean dose, and 94 cGy vs. 53 at minimum dose. The differences of maximum dose, minimum dose, and mean dose of the wMRI-based plan were lower than the lMRI-based plan, because the air cavity was not calculated in the wMRI-based plan. These results prove the feasibility of the lMRI-based planning for brain tumor radiation therapy.

Theoretical Research for Unmanned Aircraft Electromagnetic Survey: Electromagnetic Field Calculation and Analysis by Arbitrary Shaped Transmitter-Loop (무인 항공 전자탐사 이론 연구: 임의 모양의 송신루프에 의한 전자기장 반응 계산 및 분석)

  • Bang, Minkyu;Oh, Seokmin;Seol, Soon Jee;Lee, Ki Ha;Cho, Seong-Jun
    • Geophysics and Geophysical Exploration
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    • v.21 no.3
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    • pp.150-161
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    • 2018
  • Recently, unmanned aircraft EM (electromagnetic) survey based on ICT (Information and Communication Technology) has been widely utilized because of the efficiency in regional survey. We performed the theoretical study on the unmanned airship EM system developed by KIGAM (Korea Institute of Geoscience and Mineral resources) as part of the practical application of unmanned aircraft EM survey. Since this system has different configurations of transmitting and receiving loops compared to the conventional aircraft EM systems, a new technique is required for the appropriate interpretation of measured responses. Therefore, we proposed a method to calculate the EM field for the arbitrary shaped transmitter and verified its validity through the comparison with analytic solution for circular loop. In addition, to simulate the magnetic responses by three-dimensionally (3D) distributed anomalies, we have adapted our algorithm to 3D frequency-domain EM modeling algorithm based on the edge-FEM (finite element method). Though the analysis on magnetic field responses from a subsurface anomaly, it was found that the response decreases as the depth of the anomaly increases or the flight altitude increases. Also, it was confirmed that the response became smaller as the resistivity of the anomaly increases. However, a nonlinear trend of the out-of-phase component is shown depending on the depth of the anomaly and the used frequency, that makes it difficult to apply simple analysis based on the mapping of the magnitude of the responses and can cause the non-uniqueness problem in calculating the apparent resistivity. Thus, it is a prerequisite to analyze the appropriate frequency band and flight altitude considering the purpose of the survey and the site conditions when conducting a survey using the unmanned aircraft EM system.

A Study on the Effects of CRM System Installment in Customer Performance of Hotel Business (호텔기업의 CRM 시스템 구축이 고객성과에 미치는 영향에 관한 연구)

  • Kim, Jeong-Seung
    • Journal of Global Scholars of Marketing Science
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    • v.11
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    • pp.147-163
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    • 2003
  • Recently it is necessary that Hotel business introduce Information Technology to enhance competitive advantage and cope with changeable business promptly in management. Thus in an effort of using Information Technology strategically, Many Hotel business tries to install CRM system (Customer Relationship Management). This study tries to analyze the effects on customer performance by installing CRM system if it is in charge of major strategic system, it can get successful customer performance. I hypothesize to resolve the problem, and search preceding study results concerning the elements of CRM Installment and Customer performance. The survey was taken to emplyees in the field of CRM installment in Luxury hotel to test the hypothesis. To summarize the results, first, CRM intallment affects CRM customer performance. in short, systematic feature, management environment, information intention, and technologic element affect it. Through this study, facing the limitation and future study are below. first, additional parameter should be considered though I reviewed the elements affecting CRM customer performance by searching and abstracting preceding studies. Second, There are lack of preceding studies because it has passed only a couple of years since Korean businesses deal with CRM system and there is the limitation to compare this result with others due to few empirical analysisses. Especilly, I can hardly find the preceding study concerning hotel industry but tries to search preceding parameter as to the customer performance of CRM system. Until now, It is needed to continual study its measurement later. I believe that more specific study and precise theoretical test be performed and they deal with current CRM system installment and facing problems in all of the korean hotels.

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The Mechanisms of Resistance to TNF in TNF-Sensitive Cancer Cells Transfected with TNF-$\alpha$ Gene Using Retroviral Vector (암세포에서 Retroviral Vector를 이용한 종양괴사인자 유전자 이입후 획득된 종양괴사인자 내성의 기전)

  • Lee, Hyuk-Pyo;Oh, Yeon-Mok;Yoo, Chul-Gyu;Kim, Young-Whan;Shim, Young-Soo;Han, Sung-Koo
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.3
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    • pp.547-558
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    • 1997
  • Background : Tumor necrosis factor(TNF) has been considered as an important candidate for cancer gene therapy based on its potent anti-tumor activity. However, since the efficiency of current techniques of gene transfer is not satisfactory, the majorities of current protocols is aiming the in vitro gene transfer to cancer cells and re-introducing genetically modified cancer cells to hoot. In previous study, it was shown that TNF-sensitive cancer cells transfected with TNF-$\alpha$ cDNA would become highly resistant to TNF. Understanding the mechanisms of TNF-resistance in TNF-$\alpha$ gene transfected cancer cells would be an important step for improving the efficacy of cancer gene therapy as well as for better understandings of tumor biology. This study was designed to evaluate the role of new protective protein synthesis in the acquired resistance to TNF of TNF-$\alpha$ gene transfected cancer cells. Method : We transfected TNF-$\alpha$ c-DNA to WEHI164, a murine fibrosarcoma cell line, using retroviral vector(pLT12SN(TNF)) and confirm the expression of TNF with PCR, ELISA, MIT assay. Then we determined the TNF resistance of TNF gene transfected cells(WEHI164-TNF) and the changes of TNF sensitivities after treatments with actinomycin D(transcription inhibitor) and cycloheximide ( translation inhibitor). Results : WEHI164 which was sensitive to TNF became resistant to TNF after being transfected with TNF-$\alpha$ gene and the resistance to TNF was partially reversed after treatment with actinomycin D, but not with cycloheximide. Conclusion : The acquired resistance to TNF after TNF-$\alpha$ gene transfection may be associated with synthesis of some protective proteins.

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The Role of MnSOD in the Mechanisms of Acquired Resistance to TNF (TNF에 대한 내성획득에서 MnSOD의 역할에 관한 연구)

  • Lee, Hyuk-Pyo;Yoo, Chul-Gyu;Kim, Young-Whan;Han, Sung-Koo;Shim, Young-Soo
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.6
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    • pp.1353-1365
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    • 1997
  • Background : Tumor necrosis factor(TNF) has been considered as an important candidate for cancer gene therapy based on its potent anti-tumor activity. However, since the efficiency of current techniques of gene transfer is not satisfactory, the majority of current protocols is aiming the in vitro gene transfer to cancer cells and re-introducing genetically modified cancer cells to host. In the previous study, it was shown that TNF-sensitive cancer cells transfected with TNF-$\alpha$ cDNA would become highly resistant to TNF, and the probability was shown that the acquired resistance to TNF might be associated with synthesis of some protective protein. Understanding the mechanisms of TNF -resistance in TNF-$\alpha$ cDNA transfected cancer cells would be. an important step for improving the efficacy of cancer gene therapy as well as for better understandings of tumor biology. This study was designed to evaluate the role of MnSOD, an antioxidant enzyme, in the acquired resistance to TNF of TNF-$\alpha$ cDN A transfected cancer cells. Method : We transfected TNF-$\alpha$ c-DNA to WEHI164(murine fibrosarcoma cell line), NCI-H2058(human mesothelioma cell line), A549(human non-small cell lung cancer cell line), ME180(human cervix cancer cell line) cells using retroviral vector(pLT12SN(TNF)) and confirm the expression of TNF with PCR, ELISA, MIT assay. Then we determined the TNF resistance of TNF-$\alpha$ cDNA transfected cells(WEHI164-TNF, NCIH2058-TNF, A549-TNF, ME180-TNF) and the changes of MnSOD mRNA expressions with Northern blot analysis. Results : The MnSOD mRNA expressions of parental cells and genetically modified cells of WEHI164 and ME180 cells(both are naturally TNF sensitive) were not significantly different The MnSOD mRNA expressions of genetically modified cells of NCI-H2058 and A549(both are naturally TNF resistant) were higher than those of the parental cells, while those of parental cells with exogenous TNF were also elevated. Conclusion : The acquired resistance to TNF after TNF-$\alpha$ cDNA transfection may not be associated with the change in the MnSOD expression, but the difference in natural TNF sensitivity of each cell may be associated with the level of the MnSOD expression.

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Quality Characteristics of Jochung Containing Various Level of Letinus edodes Powder (표고버섯 가루를 이용한 조청의 품질 특성)

  • Park, Jung-Suk;Na, Hwan-Sik
    • Korean Journal of Food Science and Technology
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    • v.37 no.5
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    • pp.768-775
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    • 2005
  • Lentinus edodes powder was added at 1-3%(w/w) to improve functional properties of jocheong. Content of crude protein, ash, crude lipids, total mineral, free sugar and reducing sugar increased with increasing amount of L. edodes powder, while viscosity and solid and carbohydrate contents decreased. Through amino acid analysis, 17 amino acids were identified and quantified, glutamic acid being the major amino acid. No significant differences were observed in fatty acid composition and pH between control and L. edodes powder-added jocheong. Addition of mushroom powder in jocheong decreased lightness, yellowness and redness in Hunter's color value. Sensor score of jucheong containing 1% of L. edodes powder was similar to that of control. Results showed jocheong containing less than 2% L. edodes powder gave highest scores in quality characteristics and sensory evaluation.

Antioxidant Activity of Rubus crataegifolius Bge. Fruit Extracts (Rubus crataegifolius Bge. 열매 추출물의 항산화 활성)

  • Moon, Kyoung-Mi;Kim, Ji-Eun;Kim, Hae-Young;Lee, Jae-Seol;Son, Gi-Ae;Nam, Soo-Wan;Kim, Byung-Woo;Lee, Jong-Hwan
    • Journal of Life Science
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    • v.21 no.9
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    • pp.1214-1218
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    • 2011
  • We investigated the fruits of Rubus crataegifolius Bge, a plant which has been traditionally used in Korea in phytotherapy, to describe antioxidant materials from plant sources. R. crataegifolius fruits were extracted with methanol and further fractionated into n-hexane, diethyl ether, and ethyl acetate. The antioxidant activity of each fraction and the residue was assessed using a 1,1-diphenyl-2-picrylhydrazyl (DPPH), $H_2O_2$ radical scavenging method, and their cytotoxicity on human primary kerationcyte (HK) was determined by an MTS assay. The R. crataegifolius fruit methanol extract showed strong antioxidant activity (75.04%, 50%) compared with vitamin C (79.9%, 54.1%) by the DPPH, and $H_2O_2$ method, respectively. The measured activity from the subsequent extracts of the methanol extract were 20.3% for n-hexane fraction (HF), 68.8% for diethyl ether fraction (DF), 67.1% for ethyl acetate fraction (EF), and 67.1% for the residue fraction (RE) by DPPH and 2.2% for HF, 1.6% for DF, 10% for EF, and 50% for the RE by $H_2O_2$ assay. An oxidative stress model of HK was established under a suitable concentration (1 mM). The cell viability of the RE treated group increased and the percentage of apoptotic cells decreased at concentrations of 0.005-0.02% RE compared with the $H_2O_2$ treated group. Fruit extracts of the medicinal plant R. crataegifolius showed potent antioxidant activity and the ability to relieve cell damage from $H_2O_2$ induced injury to HK.

Effect of Alkaline Ionized Water on Stabilization of Antioxidation, Antithrombosis and Antibacterial Activities (항산화, 항혈전 및 항세균 활성의 안정화에 미치는 알칼리 이온수의 영향)

  • Ahn, Seon-Mi;Kang, Mee-A;Kim, Moo-In;Sohn, Ho-Yong
    • Journal of Life Science
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    • v.20 no.7
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    • pp.1107-1112
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    • 2010
  • In this study, the stable maintenance of bioactivity in alkaline ionized water (AIW) and antibacterial effects of AIW were evaluated to confirm benefits of AIW. As controls, purified water (PW) and tap drinking water (DW) were used. The pH and ORP (oxidation-reduction potential) of AIW, PW and DW used were 9.5 and 120 mV, 7.2 and 144 mV, and 7.3 and 564 mV, respectively. High level of minerals was observed in DW (DW>AIW>PW of mineral contents). Concentrations of $Ca^{++}$ and $Na^+$ in DW were 14.5, and 8.4 mg/l, respectively, while no $Ca^{++}$, $Mg^{++}$, $K^+$, and $Na^+$ were detected in PW. Evaluation of antioxidant activities for AIW, PW and DW showed that the waters did not act as antioxidants. However, the DPPH (1,1-diphenyl-2-picryl hydrazyl) or superoxide radical scavenging activities or reducing power of vitamin C were stably maintained in AIW and PW, though not in DW, against heat treatment ($60^{\circ}C$) or vigorous shaking (120 rpm) at $37^{\circ}C$. Similarly, after aspirin treatment at $60^{\circ}C$ for 1 hr, the antithrombosis activity in PW and AIW was 62.6% and 55.3%, while that of DW was 52.1%. Furthermore, cell growth analysis and viable cell count of Escherichia coli H7:O157 in PW, AIW and DW showed that AIW and DW, not DW, have antibacterial activities. Our results suggest that the state of water, for example pH, ORP and mineral contents of water, should be considered in medicine or food industries, and that AIW has high potential for utilization in various fields.