Sejong University

About: Sejong University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Graphene & Computer science. The organization has 5498 authors who have published 15236 publications receiving 330762 citations.

Application of convolutional neural networks featuring Bayesian optimization for landslide susceptibility assessment

Abstract: This study developed a deep learning based technique for the assessment of landslide susceptibility through a one-dimensional convolutional network (1D-CNN) and Bayesian optimisation in Southern Yangyang Province, South Korea. A total of 219 slide inventories and 17 slide conditioning variables were obtained for modelling. The data showed a complex scenario. Some past slides have spread over steep lands, while others have spread through flat terrain. Random forest (RF) served to keep only important factors for further analysis as a pre-processing measure. To select CNN hyperparameters, Bayesian optimization was used. Three methods contributed to overcoming the overfitting issue owing to small training data in our research. The selection of key factors by RF helped first of all to reduce information dimensionality. Second, the CNN model with 1D convolutions was intended to considerably decrease the number of its parameters. Third, a high rate of drop-out (0.66) helped reduce the CNN parameters. Overall accuracy, area under the receiver operating characteristics curve (AUROC) and 5-fold cross-validation were used to evaluate the models. CNN performance was compared to ANN and SVM. CNN achieved the highest accuracy on testing dataset (83.11%) and AUROC (0.880, 0.893, using testing and 5-fold CV, respectively). Bayesian optimization enhanced CNN accuracy by~3% (compared with default configuration). CNN could outperform ANN and SVM owing to its complicated architecture and handling of spatial correlations through convolution and pooling operations. In complex situations where some variables make a non-linear contribution to the occurrence of landslides, the method suggested could thus help develop landslide susceptibility maps.

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: a tomographic measurement of cosmic structure growth and expansion rate based on optimal redshift weights

Abstract: We develop a new method, which is based on the optimal redshift weighting scheme, to extract the maximal tomographic information of baryonic acoustic oscillations (BAO) and redshift space distortions (RSD) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 14 quasar (DR14Q) survey. We validate our method using the Extended Zel'dovich mocks, and apply our pipeline to the eBOSS DR14Q sample in the redshift range of 0.8 < z < 2.2. We report a joint measurement of fσ and two-dimensional BAO parameters D and H at four effective redshifts of zeff = 0.98, 1.23, 1.52, and 1.94, and provide the full data covariance matrix. Using our measurement combined with BOSS DR12, Main Galaxy Sample (MGS), and 6 degree Field Galaxy Survey (6dFGS) BAO measurements, we find that the existence of dark energy is supported by observations at a 7.4σ significance level. Combining our measurement with BOSS DR12 and Planck observations, we constrain the gravitational growth index to be γ = 0.580 ± 0.082, which is fully consistent with the prediction of general relativity. This paper is part of a set that analyses the eBOSS DR14 quasar sample.

The role of tumor microenvironment in therapeutic resistance.

Abstract: // Beomseok Son 1,* , Sungmin Lee 1,* , HyeSook Youn 2,* , EunGi Kim 1 , Wanyeon Kim 3,4 and BuHyun Youn 1,4 1 Department of Integrated Biological Science, Pusan National University, Busan 46241, Republic of Korea 2 Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul 05006, Republic of Korea 3 Integrative Graduate Program of Ship and Offshore Plant Technology for Ocean Energy Resource, Pusan National University, Busan 46241, Republic of Korea 4 Department of Biological Sciences, Pusan National University, Busan 46241, Republic of Korea * These authors have contributed equally to this work Correspondence to: BuHyun Youn, email: // Wanyeon Kim, email: // Keywords : tumor microenvironment, therapeutic resistance, myeloid cells, cancer-associated fibroblasts, mesenchymal stem cells Received : September 02, 2016 Accepted : December 01, 2016 Published : December 11, 2016 Abstract Cancer cells undergo unlimited progression and survival owing to activation of oncogenes. However, support of the tumor microenvironment is essential to the formation of clinically relevant tumors. Recent evidence indicates that the tumor microenvironment is a critical regulator of immune escape, progression, and distant metastasis of cancer. Moreover, the tumor microenvironment is known to be involved in acquired resistance of tumors to various therapies. Despite significant advances in chemotherapy and radiotherapy, occurrence of therapeutic resistance leads to reduced efficacy. This review highlights myeloid cells, cancer-associated fibroblasts, and mesenchymal stem cells consisting of the tumor microenvironment, as well as the relevant signaling pathways that eventually render cancer cells to be therapeutically resistant.

Very high gravity (VHG) ethanolic brewing and fermentation: a research update

Abstract: There have been numerous developments in ethanol fermentation technology since the beginning of the new millennium as ethanol has become an immediate viable alternative to fast-depleting crude reserves as well as increasing concerns over environmental pollution. Nowadays, although most research efforts are focused on the conversion of cheap cellulosic substrates to ethanol, methods that are cost-competitive with gasoline production are still lacking. At the same time, the ethanol industry has engaged in implementing potential energy-saving, productivity and efficiency-maximizing technologies in existing production methods to become more viable. Very high gravity (VHG) fermentation is an emerging, versatile one among such technologies offering great savings in process water and energy requirements through fermentation of higher concentrations of sugar substrate and, therefore, increased final ethanol concentration in the medium. The technology also allows increased fermentation efficiency, without major alterations to existing facilities, by efficient utilization of fermentor space and elimination of known losses. This comprehensive research update on VHG technology is presented in two main sections, namely VHG brewing, wherein the effects of nutrients supplementation, yeast pitching rate, flavour compound synthesis and foam stability under increased wort gravities are discussed; and VHG bioethanol fermentation studies. In the latter section, aspects related to the role of osmoprotectants and nutrients in yeast stress reduction, substrates utilized/tested so far, including saccharide (glucose, sucrose, molasses, etc.) and starchy materials (wheat, corn, barley, oats, etc.), and mash viscosity issues in VHG bioethanol production are detailed. Thereafter, topics common to both areas such as process optimization studies, mutants and gene level studies, immobilized yeast applications, temperature effect, reserve carbohydrates profile in yeast, and economic aspects are discussed and future prospects are summarized.