• Journal of Intelligence and Information Systems
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• v.26 no.2
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• pp.43-56
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• 2020

Recommender systems help users make the best choice among various options. Especially, recommender systems play important roles in internet sites as digital information is generated innumerable every second. Many studies on recommender systems have focused on an accurate recommendation. However, there are some problems to overcome in order for the recommendation system to be commercially successful. First, there is a lack of transparency in the recommender system. That is, users cannot know why products are recommended. Second, the recommender system cannot immediately reflect changes in user preferences. That is, although the preference of the user's product changes over time, the recommender system must rebuild the model to reflect the user's preference. Therefore, in this study, we proposed a recommendation methodology using topic modeling and sequential association rule mining to solve these problems from review data. Product reviews provide useful information for recommendations because product reviews include not only rating of the product but also various contents such as user experiences and emotional state. So, reviews imply user preference for the product. So, topic modeling is useful for explaining why items are recommended to users. In addition, sequential association rule mining is useful for identifying changes in user preferences. The proposed methodology is largely divided into two phases. The first phase is to create user profile based on topic modeling. After extracting topics from user reviews on products, user profile on topics is created. The second phase is to recommend products using sequential rules that appear in buying behaviors of users as time passes. The buying behaviors are derived from a change in the topic of each user. A collaborative filtering-based recommendation system was developed as a benchmark system, and we compared the performance of the proposed methodology with that of the collaborative filtering-based recommendation system using Amazon's review dataset. As evaluation metrics, accuracy, recall, precision, and F1 were used. For topic modeling, collapsed Gibbs sampling was conducted. And we extracted 15 topics. Looking at the main topics, topic 1, top 3, topic 4, topic 7, topic 9, topic 13, topic 14 are related to "comedy shows", "high-teen drama series", "crime investigation drama", "horror theme", "British drama", "medical drama", "science fiction drama", respectively. As a result of comparative analysis, the proposed methodology outperformed the collaborative filtering-based recommendation system. From the results, we found that the time just prior to the recommendation was very important for inferring changes in user preference. Therefore, the proposed methodology not only can secure the transparency of the recommender system but also can reflect the user's preferences that change over time. However, the proposed methodology has some limitations. The proposed methodology cannot recommend product elaborately if the number of products included in the topic is large. In addition, the number of sequential patterns is small because the number of topics is too small. Therefore, future research needs to consider these limitations.

• Korean Journal of Food Science and Technology
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• v.46 no.5
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• pp.641-647
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• 2014

In this study, we evaluated the effect of Capsosiphon fulvescens extract (CFE) and its active compound, pheophorbide A (PhA), on diabetic kidney failure. Diabetes mellitus (DM) was induced by a single intraperitoneal injection of streptozotocin (STZ; 40 mg/kg body weight (BW)). After a week, the rats were orally administered CFE (4 and 20 mg/kg BW) or PhA (0.2 mg/kg BW) once a day for 9 weeks. After scarification, renal tissue samples were collected for biochemical and histochemical analyses. Our study showed that the treatment with CFE and PhA significantly decreased lipid peroxidation level and the activities of glutathione peroxidase and glutathione-S-transferase (p<0.05), but it increased glutathione level and the activities of glutathione reductase, superoxide dismutase, and catalase in the renal tissues (p<0.05). The CFE- and PhA-treated rats with DM showed improved histochemical appearance and decreased abnormal glycogen accumulation. Therefore, we suggest that PhA-containing CFE could exert renal protective effects against STZ-induced oxidative stress.

• Journal of Nutrition and Health
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• v.50 no.3
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• pp.225-235
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• 2017

Purpose: This study aimed to investigate the potential of freeze-dried persimmon powder (Diospyros kaki Thumb.) to protect against dyslipidemia induced by a high-fat/cholesterol diet (HFD) in a rat model. Methods: Fifty Wistar rats were randomly divided into five groups: normal control (NC), high-fat/cholesterol control (HC), tannin in HFD (HT, 1% of diet), immature persimmon in HFD (HI, 7% of diet), and mature persimmon in HFD (HM, 7% of diet). Tannin was used as a positive control. Biochemical, molecular, and histopathological changes were observed in the blood and liver. Results: We confirmed that a high fat/cholesterol diet successfully induced dyslipidemia, which was characterized by significantly altered lipid profiles in the plasma and liver. However, oxidized low-density lipoprotein levels, histopathological damage in the liver, and hepatic triglyceride levels were significantly reduced in all HT, HI, and HM groups compared to those in the HF group. In contrast, plasma apolipoprotein B level was significantly reduced only in the HT and HM groups, whereas reduction of the LDL-C level was detected only in the HI group. Although HF-induced sterol regulatory element-binding protein (SREBP) gene expression was significantly reduced in all treated groups, downstream gene expression levels varied among the different groups; significant reduction of fatty acid synthase (FAS) and 3-hydroxy-3-methylglutaryl-CoA (HMGCR) gene expression was detected only in the HI group, whereas cholesterol $7{\alpha}$-hydroxylase (CYP7A1) gene expression was significantly elevated only in the HM group. Conclusion: Taken together, the data suggest that protection of LDL oxidation and hepatic lipogenesis might be, at least partly, attributed to tannin in persimmons. However, the identified mechanisms varied up to the maturation stage of persimmon. In the case of immature persimmon, modulation of FAS and HMGCR gene expression was prominent, whereas in the case of mature persimmon, modulation of CYP7A1 gene expression was prominent.

• The Korean Journal of Archival Studies
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• no.16
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• pp.97-146
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• 2007

Those days when people used paper to make up and manage all kinds of documents in the process of their jobs are gone now. Today electronic types of documents have replaced paper. Unlike paper documents, electronic ones contribute to the maximum job efficiency with their convenience in production and storage. But they too have some disadvantages; it's difficult to distinguish originals and copies like paper documents; it's not easy to examine if there is a change or damage to the documents; they are also prone to alteration and damage by the external influences in the electronic environment; and electronic documents require enormous amounts of workforce and costs for immediate measures to be taken according to the changes to the S/W and H/W environment. Despite all those weaknesses, however, electronic documents increasingly account for more percentage in the current job environment thanks to their job convenience and efficiency of production costs. Both the government and private sector have made efforts to come up with plans to maximize their advantages and minimize their risks at the same time. One of the methods is the Authorized Retention Center which is described in the study. There are a couple of prerequisites for its smooth operation; they should guarantee the legal validity of electronic documents in the administrative aspects and first secure the reliability and authenticity of electronic documents in the technological aspects. Responding to those needs, the Ministry of Commerce, Industry and Energy and the Korea Institute for Electronic Commerce, which were the two main bodies to drive the Authorized Retention Center project, revised the Electronic Commerce Act and supplemented the provisions to guarantee the legal validity of electronic documents in 2005 and conducted researches on the ways to preserve electronic documents for a long term and secure their reliability, which had been demanded by the users of the center, in 2006. In an attempt to fulfill those goals of the Authorized Retention Center, this study researched technical standard for electronic record information package of the center and applied the ISO 14721 information package model that's the standard for the long-term preservation of digital data. It also suggested a process to produce and manage information package so that there would be the SIP, AIP and DIP metadata features for the production, preservation, and utilization by users points of electronic documents and they could be implemented according to the center's policies. Based on the previous study, the study introduced the flow charts among the production and progress process, application methods and packages of technical standard for electronic record information package at the center and suggested some issues that should be consistently researched in the field of records management based on the results.

• Clean Technology
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• v.27 no.3
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• pp.232-239
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• 2021

In order to develop a novel system named "thermal medium and gas circulation type pyrolysis system," this study was conducted to obtain basic data for process simulation before performing the pyrolysis experiment. Polypropylene (PP) was chosen as model material in the basic pyrolysis experiment instead of waste plastic and fluidized sand (hereinafter referred to as "sand"), and it was used as a heat transfer material in the "thermal medium and gas circulation type pyrolysis system." Ni was impregnated as an active catalyst on the sand to promote catalytic pyrolysis. The basic physical properties of PP were analyzed using a thermogravimetric analyzer, and pyrolysis was performed at 600 ℃ in an N₂ atmosphere to produce liquid oil. The distribution of the carbon number of the liquid oil generated through the catalytic pyrolysis reaction was analyzed using GC/MS. We investigated the effects of varying the pyrolysis space velocity and catalyst amount on the yield of liquid oil and the carbon number distribution of the liquid oil. Using Ni/sand, the yield of liquid oil was increased except with the pyrolysis condition of 10 wt% Ni/sand at a space velocity of 30,000 h^-1, and the composition of C₆ ~ C₁₂ hydrocarbons increased. With increases in the space velocity, higher yields of liquid oil were obtained, but the composition of C₆ ~ C₁₂ hydrocarbons was reduced. With 1 wt% Ni/sand, the oil yield obtained was greater than that obtained with 10 wt% Ni/sand. In summary, when 1 wt% Ni/sand was used at a space velocity of 10,000 h^-1, the oil yield was 60.99 wt% and the composition of C₆ ~ C₁₂ hydrocarbons was highest at 42.06 area%.

• Journal of Korea Water Resources Association
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• v.55 no.6
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• pp.393-404
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• 2022

Reliable terrestrial rainfall observations from satellites at finer spatial resolution are essential for urban hydrological and microscale agricultural demands. Although various traditional "top-down" approach-based satellite rainfall products were widely used, they are limited in spatial resolution. This study aims to assess the potential of a novel "bottom-up" approach for rainfall estimation, the parameterized SM2RAIN model, applied to the C-band SAR Sentinel-1 satellite data (SM2RAIN-S1), to generate high-spatial-resolution terrestrial rainfall estimates (0.01° grid/6-day) over Central South Korea. Its performance was evaluated for both spatial and temporal variability using the respective rainfall data from a conventional reanalysis product and rain gauge network for a 1-year period over two different sub-regions in Central South Korea-the mixed forest-dominated, middle sub-region and cropland-dominated, west coast sub-region. Evaluation results indicated that the SM2RAIN-S1 product can capture general rainfall patterns in Central South Korea, and hold potential for high-spatial-resolution rainfall measurement over the local scale with different land covers, while less biased rainfall estimates against rain gauge observations were provided. Moreover, the SM2RAIN-S1 rainfall product was better in mixed forests considering the Pearson's correlation coefficient (R = 0.69), implying the suitability of 6-day SM2RAIN-S1 data in capturing the temporal dynamics of soil moisture and rainfall in mixed forests. However, in terms of RMSE and Bias, better performance was obtained with the SM2RAIN-S1 rainfall product over croplands rather than mixed forests, indicating that larger errors induced by high evapotranspiration losses (especially in mixed forests) need to be included in further improvement of the SM2RAIN.

• Korean Journal of Plant Resources
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• v.35 no.4
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• pp.417-427
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• 2022

In this study, we investigated in vitro immuno-stimulatory and anti-obesity activity of fruit (LIF), leaves (LIL) and stems (LIS) from Lonicera insularis Nakai in mouse macrophages RAW264.7 cells and mouse pre-adipocytes 3T3-L1 cells. LIF, LIL and LIS increased the production of immunostimulatory factors such as nitric oxide (NO), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α) and activated phagocytosis in RAW264.7 cells. Inhibition of toll-like receptor 2/4 (TLR2/4) partly blocked LIF, LIL and LIS mediated production of immunostimulatory factors. In addition, inhibition of mitogen-activated protein kinases (MAPK) signaling attenuated the production of immunostimulatory factors induced by LIF, LIL and LIS. Based on these results of this study, LIF, LIL and LIS is thought to activate macrophages the production of immunostimulatory factors and phagocytosis through toll-like receptor 2/4 (TLR2/4) and MAPKs signaling pathway. In anti-obesity study, LIF reduced the lipid accumulation in 3T3-L1 cells. LIF increased the protein phosphorylation expressions such as AMP-activated protein kinase (AMPK), hormone sensitive lipase (HSL), adipose triglyceride lipase (ATGL) related to the lipolysis of the adipocytes. In addition, LIF increased the expression of proteins involved in energy metabolism and brown adipose tissues differentiation such as peroxisome proliferator-activated receptor gamma coativator 1α (PGC-1α) and PR domain-containing16 (PRDM16). These results suggest that LIF is involved in lipid accumulation inhibition through expressing the proteins such as lipolysis and differentiation of white adipocytes to brown adipocytes.

• Korean Journal of Culture and Arts Education Studies
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• v.5 no.1
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• pp.97-147
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• 2010

Under the recent trend of globalization, a new proposal on education has not been able to avoid the request for multi-cultural trend. Furthermore, education has been exposed to circumstances which are far different from the previous situations in which global cooperation and intercultural understanding have been more emphasized. 'Educational Nomadism'is a metaphor of creating new value and significance of education. In fact, transnational education which could be a crisis and opportunity at the same time has recently been the mainstream throughout the world. In terms of education, Korea has encountered base hollowing-out in which excessive dependence on the US education and autonomous education coexist. In fact, the world has spent a lot of time and money to have better educational background on a resume through redundant expense by the government and parents. Under this critical situation, it's urgent to change Korea's modern education into a creative educational system in connection with an advanced foreign educational system and further develop the advantage of Korea's education. A parent's investment in his/her child is a support to create new culture as well as an assistance for hope and better future of Korean education. A new direction of parents' education fever that has opened a door to global communitas can stir up infinite potential through which the flow of education fever can be changed to the resources of new civilization. The global cooperation and efforts for communitas means the communication with this world. Through this communication, the culture in which people are forced to zero-sum competition can leap into the education for change of civilization which creates pleasure of self sufficiency and donation.

• Journal of Nutrition and Health
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• v.56 no.6
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• pp.602-614
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• 2023

Purpose: The balance between synthesis and degradation of proteins plays a critical role in the maintenance of skeletal muscle mass. Mitochondrial dysfunction has been closely associated with skeletal muscle atrophy caused by aging, cancer, and chemotherapy. Polygalacin D is a saponin derivative isolated from Platycodon grandiflorum (Jacq.) A. DC. This study aimed to investigate the effects of polygalacin D on myoblast differentiation and muscle atrophy in association with mitochondrial function in in vitro and in zebrafish models in vivo. Methods: C2C12 myoblasts were cultured in differentiation media containing different concentrations of polygalacin D, followed by the immunostaining of the myotubes with myosin heavy chain (MHC). The mRNA expression of markers related to myogenesis, muscle atrophy, and mitochondrial function was determined by real-time quantitative reverse transcription polymerase chain reaction. Wild type AB^* zebrafish (Danio rerio) embryos were treated with 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) with or without polygalacin D, and immunostained to detect slow and fast types of muscle fibers. The Tg(Xla.Eef1a1:mitoEGFP) zebrafish expressing mitochondria-targeted green fluorescent protein was used to monitor mitochondrial morphology. Results: The exposure of C2C12 myotubes to 0.1 ng/mL of polygalacin D increased the formation of MHC-positive multinucleated myotubes (≥ 8 nuclei) compared with the control. Polygalacin D significantly increased the expression of MHC isoforms (Myh1, Myh2, Myh4, and Myh7) involved in myoblast differentiation while it decreased the expression of atrophic markers including muscle RING-finger protein-1 (MuRF1), mothers against decapentaplegic homolog (Smad)2, and Smad3. In addition, polygalacin D promoted peroxisome proliferator-activated receptor-gamma coactivator (Pgc1α) expression and reduced the level of mitochondrial fission regulators such as dynamin-1-like protein (Drp1) and mitochondrial fission 1 (Fis1). In a zebrafish model of FOLFIRI-induced muscle atrophy, polygalacin D improved not only mitochondrial dysfunction but also slow and fast muscle fiber atrophy. Conclusion: These results demonstrated that polygalacin D promotes myogenesis and alleviates chemotherapy-induced muscle atrophy by improving mitochondrial function. Thus, polygalacin D could be useful as nutrition support to prevent and ameliorate muscle wasting and weakness.

• Korean Journal of Remote Sensing
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• v.40 no.4
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• pp.387-396
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• 2024

Most very high-resolution (VHR) satellite images provide rational polynomial coefficients (RPC) data to facilitate the transformation between ground coordinates and image coordinates. However, initial RPC often contains geometric errors, necessitating correction through matching with ground control points (GCPs). A GCP chip is a small image patch extracted from an orthorectified image together with height information of the center point, which can be directly used for geometric correction. Many studies have focused on area-based matching methods to accurately align GCP chips with VHR satellite images. In cases with seasonal differences or changed areas, edge-based algorithms are often used for matching due to the difficulty of relying solely on pixel values. However, traditional edge extraction algorithms,such as canny edge detectors, require appropriate threshold settings tailored to the spectral characteristics of satellite images. Therefore, this study utilizes deep learning-based edge information that is insensitive to the regional characteristics of satellite images for matching. Specifically,we use a pretrained pixel difference network (PiDiNet) to generate the edge maps for both satellite images and GCP chips. These edge maps are then used as input for normalized cross-correlation (NCC) and relative edge cross-correlation (RECC) to identify the peak points with the highest correlation between the two edge maps. To remove mismatched pairs and thus obtain the bias-compensated RPC, we iteratively apply the data snooping. Finally, we compare the results qualitatively and quantitatively with those obtained from traditional NCC and RECC methods. The PiDiNet network approach achieved high matching accuracy with root mean square error (RMSE) values ranging from 0.3 to 0.9 pixels. However, the PiDiNet-generated edges were thicker compared to those from the canny method, leading to slightly lower registration accuracy in some images. Nevertheless, PiDiNet consistently produced characteristic edge information, allowing for successful matching even in challenging regions. This study demonstrates that improving the robustness of edge-based registration methods can facilitate effective registration across diverse regions.