• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.5820-5834
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• 2017

This paper investigates the channel selection problem with dynamic users and the asymmetric interference relation in distributed opportunistic spectrum access systems. Since users transmitting data are based on their traffic demands, they dynamically compete for the channel occupation. Moreover, the heterogeneous interference range leads to asymmetric interference relation. The dynamic users and asymmetric interference relation bring about new challenges such as dynamic random systems and poor fairness. In this article, we will focus on maximizing the tradeoff between the achievable utility and access cost of each user, formulate the channel selection problem as a directional graphical game and prove it as an exact potential game presenting at least one pure Nash equilibrium point. We show that the best NE point maximizes both the personal and system utility, and employ the stochastic learning approach algorithm for achieving the best NE point. Simulation results show that the algorithm converges, presents near-optimal performance and good fairness, and the directional graphical model improves the systems throughput performance in different asymmetric level systems.

• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.121-125
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• 2022

This paper deals with the development of a deep-learning-based robot that recognizes various types of stairs and performs a mission to go up to the target floor. The overall motion sequence of the robot is performed based on the ROS robot operating system, and it is possible to detect the shape of the stairs required to implement the motion sequence through rapid object recognition through YOLOv4 and Cuda acceleration calculations. Using the ROS operating system installed in Jetson Nano, a system was built to support communication between Arduino DUE and OpenCM 9.04 with heterogeneous hardware and to control the movement of the robot by aligning the received sensors and data. In addition, the web server for robot control was manufactured as ROS web server, and flow chart and basic ROS communication were designed to enable control through computer and smartphone through message passing.

• 인터넷정보학회논문지
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• 제23권5호
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• pp.17-23
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• 2022

Network slicing is a promising paradigm and significant evolution for adjusting the heterogeneous services based on different requirements by placing dynamic virtual network functions (VNF) forwarding graph (VNFFG) and orchestrating service function chaining (SFC) based on criticalities of Quality of Service (QoS) classes. In system architecture, software-defined networks (SDN), network functions virtualization (NFV), and edge computing are used to provide resourceful data view, configurable virtual resources, and control interfaces for developing the modified deep reinforcement learning agent (MDRL-A). In this paper, task requests, tolerable delays, and required resources are differentiated for input state observations to identify the non-critical/critical classes, since each user equipment can execute different QoS application services. We design intelligent slicing for handing the cross-domain resource with MDRL-A in solving network problems and eliminating resource usage. The agent interacts with controllers and orchestrators to manage the flow rule installation and physical resource allocation in NFV infrastructure (NFVI) with the proposed formulation of completion time and criticality criteria. Simulation is conducted in SDN/NFV environment and capturing the QoS performances between conventional and MDRL-A approaches.

• 한국전자통신학회논문지
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• 제17권6호
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• pp.1283-1292
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• 2022

현재 보건의료 분야에서 여러 인공지능 프로젝트가 서로 경쟁하고 있어서 시스템 간 인터페이스의 통일된 사양이 부족한 상황이다. 이에 본 연구에서는 보건의료 부문 관련 응용 알고리즘, 모델 및 서비스 지원을 제공할 수 있는 하나의 보건의료 인공지능 서비스 플랫폼을 제안한다. 제안된 플랫폼은 다수의 이기종 데이터 처리, 지능형 서비스, 모델 관리, 일반 응용 시나리오 및 다양한 수준의 비즈니스를 위한 기타 서비스를 제공할 수 있다. 플랫폼 적용과 관련해서 최근 대두되고 있는 행위 인터넷 개념을 바탕으로 보건의료 분야의 사물 인터넷 서비스 관련 환자 행위 분석을 통해 보건의료 소비 행위에 대해 신뢰할 수 있고, 이해 가능한 추적 및 분석 시나리오를 나타낸다.

• Korean Journal of Radiology
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• 제25권6호
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• pp.550-558
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• 2024

Hepatocellular carcinoma (HCC) is a biologically heterogeneous tumor characterized by varying degrees of aggressiveness. The current treatment strategy for HCC is predominantly determined by the overall tumor burden, and does not address the diverse prognoses of patients with HCC owing to its heterogeneity. Therefore, the prognostication of HCC using imaging data is crucial for optimizing patient management. Although some radiologic features have been demonstrated to be indicative of the biologic behavior of HCC, traditional radiologic methods for HCC prognostication are based on visually-assessed prognostic findings, and are limited by subjectivity and inter-observer variability. Consequently, artificial intelligence has emerged as a promising method for image-based prognostication of HCC. Unlike traditional radiologic image analysis, artificial intelligence based on radiomics or deep learning utilizes numerous image-derived quantitative features, potentially offering an objective, detailed, and comprehensive analysis of the tumor phenotypes. Artificial intelligence, particularly radiomics has displayed potential in a variety of applications, including the prediction of microvascular invasion, recurrence risk after locoregional treatment, and response to systemic therapy. This review highlights the potential value of artificial intelligence in the prognostication of HCC as well as its limitations and future prospects.

• 정보처리학회논문지D
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• 제18D권5호
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• pp.385-392
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• 2011

최근 농업 분야에 IT를 접목시킨 농업-IT 융합 기술에 대한 연구가 주목 받고 있다. 특히, 공간 데이터 마이닝(spatial data mining, SDM)을 이용한 농작물 관련 예측 서비스들을 통해 자연재해에 대한 피해를 줄이고 농작물의 생산성을 높이고자 하는 연구들이 있어 왔다. 그러나 예측 서비스를 위한 SDM에 필요한 학습 데이터는 분산되어 있는 데이터간의 이질성으로 인해 데이터 변환과 통합과정에 많은 비용과 시간이 발생한다. 또한 공간 데이터와 비공간 데이터 간의 공간적 이웃 관계를 연산하기 위해 대용량의 데이터에 대한 복잡한 연산과정이 필요하다. 본 논문에서는 각각의 데이터 소스를 하나의 서비스 단위로 취급함으로써 분산된 이질적인 데이터를 효과적으로 통합 관리할 수 있고 SDM을 위한 학습 데이터의 생산성을 향상시켜 최적의 예측 서비스의 발견을 지원해 주는 SOA 기반의 데이터 통합 프레임워크를 제안한다. 실험을 통해 경기도 이천시의 복숭아나무의 동해 피해지역에 대한 최적의 예측 서비스의 발견을 위해 제안 프레임워크를 효과적으로 적용할 수 있음을 확인하였다.

• Journal of Information Processing Systems
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• 제16권6호
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• pp.1238-1249
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• 2020

Throughout the world, aging populations and doctor shortages have helped drive the increasing demand for smart healthcare systems. Recently, these systems have benefited from the evolution of the Internet of Things (IoT), big data, and machine learning. However, these advances result in the generation of large amounts of data, making healthcare data analysis a major issue. These data have a number of complex properties such as high-dimensionality, irregularity, and sparsity, which makes efficient processing difficult to implement. These challenges are met by big data analytics. In this paper, we propose an innovative analytic framework for big healthcare data that are collected either from IoT wearable devices or from archived patient medical images. The proposed method would efficiently address the data heterogeneity problem using middleware between heterogeneous data sources and MapReduce Hadoop clusters. Furthermore, the proposed framework enables the use of both fog computing and cloud platforms to handle the problems faced through online and offline data processing, data storage, and data classification. Additionally, it guarantees robust and secure knowledge of patient medical data.

• Smart Structures and Systems
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• 제29권1호
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• pp.63-75
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• 2022

The raw data collected by structural health monitoring (SHM) systems may suffer multiple patterns of anomalies, which pose a significant barrier for an automatic and accurate structural condition assessment. Therefore, the detection and classification of these anomalies is an essential pre-processing step for SHM systems. However, the heterogeneous data patterns, scarce anomalous samples and severe class imbalance make data anomaly detection difficult. In this regard, this study proposes a convolutional neural network-based data anomaly detection method. The time and frequency domains data are transferred as images and used as the input of the neural network for training. ResNet18 is adopted as the feature extractor to avoid training with massive labelled data. In addition, the focal loss function is adopted to soften the class imbalance-induced classification bias. The effectiveness of the proposed method is validated using acceleration data collected in a long-span cable-stayed bridge. The proposed approach detects and classifies data anomalies with high accuracy.

• 디지털융복합연구
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• 제18권3호
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• pp.189-194
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• 2020

최근 IoT 네트워크는 이기종의 IoT 장치에서 발생하는 데이터를 효율적으로 처리하기 위해서 다양한 클러스터링 기법들이 연구되고 있다. 그러나, 기존 클러스터링 기법들은 정적으로 네트워크를 분할하는데 초점을 맞추고 있어서 이동이 가능한 IoT 장치에는 기존 클러스터링 기법들이 적합하지 않다. 본 논문에서는 에지 네트워크를 이용하여 IoT 장치의 정보를 수집·분석하기 위한 확률적 딥러닝 기반의 동적 클러스터링 모델을 제안한다. 제안 모델은 수집된 정보의 속성값의 빈도수를 확률적으로 딥러닝에 적용하여 서브넷을 구축한다. 구축된 서브넷은 시드로 추출된 연계 정보를 계층적 구조로 그룹핑할 때 사용하며, IoT 장치에 대한 동적 클러스터링의 속도 및 정확도를 향상시킨다. 성능평가 결과, 제안모델은 기존 모델에 비해 데이터 처리 시간이 평균 13.8% 향상되었고, 서버의 오버헤드는 기존 모델보다 평균 10.5% 낮게 나타났다. 서버에서 IoT 정보를 추출할 때의 정확도는 기존모델보다 평균 8.7% 향상되었다.

• Geomechanics and Engineering
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• 제9권4호
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• pp.465-481
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• 2015

Three-dimensional simulation of flow through dam foundation is performed using finite element (Seep3D model) and artificial neural network (ANN) models. The governing and discretized equation for seepage is obtained using the Galerkin method in heterogeneous and anisotropic porous media. The ANN is a feedforward four layer network employing the sigmoid function as an activator and the back-propagation algorithm for the network learning, using the water level elevations of the upstream and downstream of the dam, as input variables and the piezometric heads as the target outputs. The obtained results are compared with the piezometric data of Shahid Abbaspour's Dam. Both calculated data show a good agreement with available measurements that demonstrate the effectiveness and accuracy of purposed methods.