• Title/Summary/Keyword: edge analysis

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Validation of GOCI-II Products in an Inner Bay through Synchronous Usage of UAV and Ship-based Measurements (드론과 선박을 동시 활용한 내만에서의 GOCI-II 산출물 검증)

  • Baek, Seungil;Koh, Sooyoon;Lim, Taehong;Jeon, Gi-Seong;Do, Youngju;Jeong, Yujin;Park, Sohyeon;Lee, Yongtak;Kim, Wonkook
    • Korean Journal of Remote Sensing
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    • v.38 no.5_1
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    • pp.609-625
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    • 2022
  • Validation of satellite data products is critical for subsequent analysis that is based on the data. Particularly, performance of ocean color products in turbid and shallow near-land ocean areas has been questioned for long time for its difficulty that stems from the complex optical environment with varying distribution of water constituents. Furthermore, validation with ship-based or station-based measurements has also exhibited clear limitation in its spatial scale that is not compatible with that of satellite data. This study firstly performed validation of major GOCI-II products such as remote sensing reflectance, chlorophyll-a concentration, suspended particulate matter, and colored dissolved organic matter, using the in-situ measurements collected from ship-based field campaign. Secondly, this study also presents preliminary analysis on the use of drone images for product validation. Multispectral images were acquired from a MicaSense RedEdge camera onboard a UAV to compensate for the significant scale difference between the ship-based measurements and the satellite data. Variation of water radiance in terms of camera altitude was analyzed for future application of drone images for validation. Validation conducted with a limited number of samples showed that GOCI-II remote sensing reflectance at 555 nm is overestimated more than 30%, and chlorophyll-a and colored dissolved organic matter products exhibited little correlation with in-situ measurements. Suspended particulate matter showed moderate correlation with in-situ measurements (R2~0.6), with approximately 20% uncertainty.

Major Class Recommendation System based on Deep learning using Network Analysis (네트워크 분석을 활용한 딥러닝 기반 전공과목 추천 시스템)

  • Lee, Jae Kyu;Park, Heesung;Kim, Wooju
    • Journal of Intelligence and Information Systems
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    • v.27 no.3
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    • pp.95-112
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    • 2021
  • In university education, the choice of major class plays an important role in students' careers. However, in line with the changes in the industry, the fields of major subjects by department are diversifying and increasing in number in university education. As a result, students have difficulty to choose and take classes according to their career paths. In general, students choose classes based on experiences such as choices of peers or advice from seniors. This has the advantage of being able to take into account the general situation, but it does not reflect individual tendencies and considerations of existing courses, and has a problem that leads to information inequality that is shared only among specific students. In addition, as non-face-to-face classes have recently been conducted and exchanges between students have decreased, even experience-based decisions have not been made as well. Therefore, this study proposes a recommendation system model that can recommend college major classes suitable for individual characteristics based on data rather than experience. The recommendation system recommends information and content (music, movies, books, images, etc.) that a specific user may be interested in. It is already widely used in services where it is important to consider individual tendencies such as YouTube and Facebook, and you can experience it familiarly in providing personalized services in content services such as over-the-top media services (OTT). Classes are also a kind of content consumption in terms of selecting classes suitable for individuals from a set content list. However, unlike other content consumption, it is characterized by a large influence of selection results. For example, in the case of music and movies, it is usually consumed once and the time required to consume content is short. Therefore, the importance of each item is relatively low, and there is no deep concern in selecting. Major classes usually have a long consumption time because they have to be taken for one semester, and each item has a high importance and requires greater caution in choice because it affects many things such as career and graduation requirements depending on the composition of the selected classes. Depending on the unique characteristics of these major classes, the recommendation system in the education field supports decision-making that reflects individual characteristics that are meaningful and cannot be reflected in experience-based decision-making, even though it has a relatively small number of item ranges. This study aims to realize personalized education and enhance students' educational satisfaction by presenting a recommendation model for university major class. In the model study, class history data of undergraduate students at University from 2015 to 2017 were used, and students and their major names were used as metadata. The class history data is implicit feedback data that only indicates whether content is consumed, not reflecting preferences for classes. Therefore, when we derive embedding vectors that characterize students and classes, their expressive power is low. With these issues in mind, this study proposes a Net-NeuMF model that generates vectors of students, classes through network analysis and utilizes them as input values of the model. The model was based on the structure of NeuMF using one-hot vectors, a representative model using data with implicit feedback. The input vectors of the model are generated to represent the characteristic of students and classes through network analysis. To generate a vector representing a student, each student is set to a node and the edge is designed to connect with a weight if the two students take the same class. Similarly, to generate a vector representing the class, each class was set as a node, and the edge connected if any students had taken the classes in common. Thus, we utilize Node2Vec, a representation learning methodology that quantifies the characteristics of each node. For the evaluation of the model, we used four indicators that are mainly utilized by recommendation systems, and experiments were conducted on three different dimensions to analyze the impact of embedding dimensions on the model. The results show better performance on evaluation metrics regardless of dimension than when using one-hot vectors in existing NeuMF structures. Thus, this work contributes to a network of students (users) and classes (items) to increase expressiveness over existing one-hot embeddings, to match the characteristics of each structure that constitutes the model, and to show better performance on various kinds of evaluation metrics compared to existing methodologies.

Text Mining and Association Rules Analysis to a Self-Introduction Letter of Freshman at Korea National College of Agricultural and Fisheries (1) (한국농수산대학 신입생 자기소개서의 텍스트 마이닝과 연관규칙 분석 (1))

  • Joo, J.S.;Lee, S.Y.;Kim, J.S.;Shin, Y.K.;Park, N.B.
    • Journal of Practical Agriculture & Fisheries Research
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    • v.22 no.1
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    • pp.113-129
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    • 2020
  • In this study we examined the topic analysis and correlation analysis by text mining to extract meaningful information or rules from the self introduction letter of freshman at Korea National College of Agriculture and Fisheries in 2020. The analysis items are described in items related to 'academic' and 'in-school activities' during high school. In the text mining results, the keywords of 'academic' items were 'study', 'thought', 'effort', 'problem', 'friend', and the key words of 'in-school activities' were 'activity', 'thought', 'friend', 'club', 'school' in order. As a result of the correlation analysis, the key words of 'thinking', 'studying', 'effort', and 'time' played a central role in the 'academic' item. And the key words of 'in-school activities' were 'thought', 'activity', 'school', 'time', and 'friend'. The results of frequency analysis and association analysis were visualized with word cloud and correlation graphs to make it easier to understand all the results. In the next study, TF-IDF(Term Frequency-Inverse Document Frequency) analysis using 'frequency of keywords' and 'reverse of document frequency' will be performed as a method of extracting key words from a large amount of documents.

The Irradiated Lung Volume in Tangential Fields for the Treatment of a Breast (유방암의 접선 조사시 피폭 폐용적)

  • Oh Young Taek;Kim Juree;Kang Haejin;Sohn Jeong Hye;Kang Seung Hee;Chun Mison
    • Radiation Oncology Journal
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    • v.15 no.2
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    • pp.137-143
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    • 1997
  • Purpose : Radiation pneumonitis is one of the complications caused by radiation therapy that includes a Portion of the lung tissue. The severity of radiation induced pulmonary dysfunction depends on the irradiated lung volume, total dose, dose rate and underlying Pulmonary function. It also depends on whether chemotherapy is done or not. The irradiated lung volume is the most important factor to predict the pulmonary dysfunction in breast cancer Patients following radiation therapy. There are some data that show the irradiated lung volume measured from CT scans as a part of treatment Planning with the tangential beams. But such data have not been reported in Korea. We planned to evaluate the irradiated lung volume quantitatively using CT scans for the breast tangential field and search for useful factors that could Predict the irradiated lung volume Materials and Methods : The lung volume was measured for 25 patients with breast cancer irradiated with tangential field from Jan.1995 to Aug.1996. Parameters that can predict the irradiated lung volume included; (1) the peruendicular distance from the Posterior tangential edge to the posterior part of the anterior chest wall at the center of the field (CLD) ; (2) the maximum perpendicular distance from the posterior tangential field edge to the posterior Part of the anterior chest wall (MLD) ; (3) the greatest perpendicular distance from the Posterior tangential edge to the posterior part of anterior chest wall on CT image at the center of the longitudinal field (GPD) ; (4) the length of the longitudinal field (L). The irradiated lung volume(RV), the entire both lung volume(EV) and the ipsilateral lung volume(IV) were measured using dose volume histogram. The relationship between the irradiated lung volume and predictors was evaluated by regression analysis. Results :The RV is 61-279cc (mean 170cc), the RV/EV is $2.9-13.0\%\;(mean\;5.8\%)$ and the RV/IV is $4.9-29.0\%\;(mean\;12.2\%)$. The CLD, the MLD and the GPD ave 1.9-3.3cm, 1.9-3.3cm and 1.4-3.1cm respectively. The significant relations between the irradiated lung volume such as RV. RV/EV, RV/IV and parameters such as CLD, MLD, GPO, L. $CLD\timesL,\;MLD\timesL\;and\;GPD\timesL$ are not found with little variances in parameters. The RV/IV of the left breast irradiation is significantly larger than that of the right but the RV/EVS do not show the differences. There is no symptomatic radiation pneumonitis at least during 6 months follow up. Conclusion : The significant relationship between the irradiated lung volume and predictors is not found with little variation on parameters. The irradiated lung volume in the tangential held is liss than $10\%$ of entire lung volume when CLO is less than 3cm. The RV/IV of the left tangential field is larger than that of the right but there was no significant differences in RV/EVS. Symptomatic radiation pneumonitis has not occurred during minimum 6 months follow up.

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Text Mining and Association Rules Analysis to a Self-Introduction Letter of Freshman at Korea National College of Agricultural and Fisheries (2) (한국농수산대학 신입생 자기소개서의 텍스트 마이닝과 연관규칙 분석 (2))

  • Joo, J.S.;Lee, S.Y.;Kim, J.S.;Shin, Y.K.;Park, N.B.
    • Journal of Practical Agriculture & Fisheries Research
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    • v.22 no.2
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    • pp.99-114
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    • 2020
  • In this study we examined the topic analysis and correlation analysis by text mining from the self introduction letter of freshman at Korea National College of Agriculture and Fisheries(KNCAF) in 2020. The analysis items of the 3rd question were and the 4th question were the motivation for applying to college, the academic plan and the career plan. The text mining to the 3rd question showed that the frequency of 'friends' was overwhelmingly high, followed by keywords such as 'thought', 'time', 'opinion', 'activity', and 'club'. In the 4th question, keyword frequency such as 'thought', 'agriculture', 'KNCAF', 'farm', 'father' was high. The result of association rules analysis for each question showed that the relationship with the highest support level, which means the frequency and importance of the rule, was the {friend} <=> {thought}, {thought} <=> {KNCAF}. The confidence level of a correlation between keywords was the highest in the rules of {teacher}=>{friend}, {agriculture, KNCAF}=>{thought}. Also the lift level that indicates the closeness of two words was the highest in the rules of {friend} <=> {teacher}, {knowledge} <=> {professional}. These keywords are found to play a very important roles in analyzing betweenness centrality and analyzing degree centrality between keywords. The results of frequency analysis and association analysis were visualized with word cloud and correlation graphs to make it easier to understand all the results.

Genetic Diversity and Structure of the Korean Endemic Species, Coreanomecon hylomeconoides Nakai, as Revealed by ISSR markers (한국 특산식물 매미꽃(Coreanomecon hylomeconoides Nakai) 집단의 유전다양성 및 구조)

  • Son, Sung-Won;Chung, Jae-Min;Kim, Eun-Hye;Choi, Kyoung-Su;Park, SeonJoo
    • Korean Journal of Plant Resources
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    • v.26 no.2
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    • pp.310-319
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    • 2013
  • The genetic diversity and structure of eight populations of Coreanomecon hylomeconoides Nakai, an endemic Korean plant, were investigated using 50 ISSR loci from eight primers. The average percentage of polymorphic loci was 47.3%. The Shannon's index (SI=0.218) and gene diversity (h=0.142) were relatively lower than those of other long-lived perennials. The Sancheong (SI=0.233, h=0153), Gwangyang (SI=0.263, h=0.171), and Suncheon (SI=0.241, h=0.159) populations showed greater genetic diversity than the Namhae and Gwangju populations, which are on the edge of the distribution. Analysis of molecular variance (AMOVA) showed that 18% of the total variation could be attributed to differences among populations, and 82% to differences within populations, indicating moderate gene flow among adjacent populations. These results were supported by value of Nm (2.184). The UPGMA conducted using the genetic distance and Bayesian cluster analysis showed a remarkable geographic trend structured into east and west regions. Overall, the results indicate that the Sancheong and Gwangyang populations, which had a large population size and higher degree of genetic diversity, should be the focus of in situ conservation.

A Study on the Extraction of a River from the RapidEye Image Using ISODATA Algorithm (ISODATA 기법을 이용한 RapidEye 영상으로부터 하천의 추출에 관한 연구)

  • Jo, Myung-Hee
    • Journal of the Korean Association of Geographic Information Studies
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    • v.15 no.4
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    • pp.1-14
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    • 2012
  • A river is defined as the watercourse flowing through its channel, and the mapping tasks of a river plays an important role for the research on the topographic changes in the riparian zones and the research on the monitoring of flooding in its floodplain. However, the utilization of the ground surveying technologies is not efficient for the mapping tasks of a river due to the irregular surfaces of the riparian zones and the dynamic changes of water level of a river. Recently, the spatial information data sets are widely used for the coastal mapping tasks due to the acquisition of the topographic information without human accessibility. In this research, we tried to extract a river from the RapidEye imagery by using the ISODATA(Iterative Self_Organizing Data Analysis) classification algorithm with the two different parameters(NIR (Near Infra-Red) band and NDVI(Normalized Difference Vegetation Index)). First, the two different images(the NIR band image and the NDVI image) were generated from the RapidEye imagery. Second, the ISODATA algorithm were applied to each image and each river was generated in each image through the post-processing steps. River boundaries were also extracted from each classified image using the Sobel edge detection algorithm. Ground truths determined by the experienced expert are used for the assessment of the accuracy of an each generated river. Statistical results show that the extracted river using the NIR band has higher accuracies than the extracted river using the NDVI.

Spatio-temporal Change Detection of Forest Landscape in the Geumho River Watershed using Landscape Metrics (경관메트릭스를 이용한 금호강 유역 산림경관의 시·공간적 변화탐지)

  • Oh, Jeong-Hak;Park, Kyung-Hun;Jung, Sung-Gwan;Lee, Jong-Won
    • Journal of the Korean Association of Geographic Information Studies
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    • v.8 no.2
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    • pp.81-94
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    • 2005
  • The purpose of this study is to test the applicability of landscape metrics for quantifying and monitoring the landscape structure in the Geumho River watershed, which has undergone heavy environmental disturbances. Landscape metrics were computed from land cover maps(1985, 1999) for the forest patches. The number of variables were reduced from 12 metrics to 3 factors through factor analysis. These factors accounted for above 91% of the variation in the original metrics. We also determined the relative effects of land development on the changes of forest landscape structure using multiple linear regression analysis. At the forest patches, the conversion of forest to urban areas and agriculture resulted in increased fragmentation. Patch area and patch size decreased. and patch density increased as a result of the conversion of forest to agriculture($R^2=0.696$, p<0.01). The heterogeneity of patch size and complexity of patch shape mainly decreased as a result of the conversion of forest to urban areas($R^2=0.405$, p<0.01). The density of core area and edge showed the tendency increase, but there was no relationship with the conversion of forest to urban area and agriculture The future research will be needed to analyze correlations between landscape structures and specific environmental and socioeconomic landscape functions.

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Regenerative capacity of augmented bone in rat calvarial guided bone augmentation model

  • Kubota, Tatsuya;Hasuike, Akira;Ozawa, Yasumasa;Yamamoto, Takanobu;Tsunori, Katsuyoshi;Yamada, Yutaka;Sato, Shuichi
    • Journal of Periodontal and Implant Science
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    • v.47 no.2
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    • pp.77-85
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    • 2017
  • Purpose: Guided bone regeneration (GBR) is the most widely used technique to regenerate and augment bones. Even though augmented bones (ABs) have been examined histologically in many studies, few studies have been conducted to examine the biological potential of these bones and the healing dynamics following their use. Moreover, whether the bone obtained from the GBR procedure possesses the same functions as the existing autogenous bone is uncertain. In particular, little attention has been paid to the regenerative ability of GBR bone. Therefore, the present study histologically evaluated the regenerative capacity of AB in the occlusive space of a rat guided bone augmentation (GBA) model. Methods: The calvaria of 30 rats were exposed, and plastic caps were placed on the right of the calvaria in 10 of the 30 rats. After a 12-week healing phase, critical-sized calvarial bone defects (diameter: 5.0 mm) were trephined into the dorsal parietal bone on the left of the calvaria. Bone particles were harvested from the AB or the cortical bone (CB) using a bone scraper and transplanted into the critical defects. Results: The newly generated bone at the defects' edge was evaluated using micro-computed tomography (micro-CT) and histological sections. In the micro-CT analysis, the radiopacity in both the augmented and the CB groups remained high throughout the observational period. In the histological analysis, the closure rate of the CB was significantly higher than in the AB group. The numbers of cells positive for runt-related transcription factor 2 (Runx2) and tartrate-resistant acid phosphatase (TRAP) in the AB group were larger than in the CB group. Conclusions: The regenerative capacity of AB in the occlusive space of the rat GBA model was confirmed. Within the limitations of this study, the regenerative ability of the AB particulate transplant was inferior to that of the CB particulate transplant.

Experimental and numerical disbond localization analyses of a notched plate repaired with a CFRP patch

  • Abderahmane, Sahli;Mokhtar, Bouziane M.;Smail, Benbarek;Wayne, Steven F.;Zhang, Liang;Belabbes, Bachir Bouiadjra;Boualem, Serier
    • Structural Engineering and Mechanics
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    • v.63 no.3
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    • pp.361-370
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    • 2017
  • Through the use of finite element analysis and acoustic emission techniques we have evaluated the interfacial failure of a carbon fiber reinforced polymer (CFRP) repair patch on a notched aluminum substrate. The repair of cracks is a very common and widely used practice in the aeronautics field to extend the life of cracked sheet metal panels. The process consists of adhesively bonding a patch that encompasses the notched site to provide additional strength, thereby increasing life and avoiding costly replacements. The mechanical strength of the bonded joint relies mainly on the bonding of the adhesive to the plate and patch stiffness. Stress concentrations at crack tips promote disbonding of the composite patch from the substrate, consequently reducing the bonded area, which makes this a critical aspect of repair effectiveness. In this paper we examine patch disbonding by calculating the influence of notch tip stress on disbond area and verify computational results with acoustic emission (AE) measurements obtained from specimens subjected to uniaxial tension. The FE results showed that disbonding first occurs between the patch and the substrate close to free edge of the patch followed by failure around the tip of the notch, both highest stress regions. Experimental results revealed that cement adhesion at the aluminum interface was the limiting factor in patch performance. The patch did not appear to strengthen the aluminum substrate when measured by stress-strain due to early stage disbonding. Analysis of the AE signals provided insight to the disbond locations and progression at the metal-adhesive interface. Crack growth from the notch in the aluminum was not observed until the stress reached a critical level, an instant before final fracture, which was unaffected by the patch due to early stage disbonding. The FE model was further utilized to study the effects of patch fiber orientation and increased adhesive strength. The model revealed that the effectiveness of patch repairs is strongly dependent upon the combined interactions of adhesive bond strength and fiber orientation.