• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2018년도 추계학술발표대회
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• pp.771-773
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• 2018

인공지능(AI), 사물인터넷(IoT)등의 4차 산업기술은 철도안전의 핵심수단으로 부상하고 있으며 차량, 위험관리, 운행관리, 보안관리 등의 점진적인 적용분야 확장을 통해 철도안전에 대한 신뢰성을 향상시킬 수 있는 방안에 대한 관심이 집중되고 있다. 본 논문에서는 IoT 기반의 다양한 철도인프라 데이터를 활용하여 열차주행상태에 영향을 줄 수 있는 이상상황 인식 모델 및 열차자율주행을 위한 제어기술에 필요한 정보로 인프라 상태를 제공하는 방식을 제안한다. 철도 인프라 상황인지에 필요한 데이터는 레일온도, 선로 지정물, 승객 수, 선로 적설량을 지정하였고, 제안 인식모델의 스게노 퍼지추론 방식을 적용한 후 철도차량 운전관련 취급규정 및 취급세척을 기반으로 퍼지규칙(Fuzzy Rule)을 15개 생성하였다. 인프라데이터셋을 활용하여 제안모델의 인식률 평가에 사용하였으며 인식률 결과는 약 86%의 정확성을 보였다. 퍼지추론 기반 방식의 철도인프라 이상상태 인식모델을 철도분야에 접목시킨다면 기존의 관제기반 방식보다 효율적인 철도인프라 상황인식이 가능할 것으로 판단된다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2019년도 제60차 하계학술대회논문집 27권2호
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• pp.113-114
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• 2019

다수의 센서 노드로 구성된 IoT 환경에서는 네트워크 수명, 센서 노드의 통신 범위 제한과 같은 제약 사항들이 있다. 이러한 한계점을 해결하기 위해 밀집된 센서 노드 간의 협력이 필요하다. 이때, 밀집된 센서 노드들은 에너지 낭비 및 전송 데이터의 정확도를 저하시킨다. 본 연구에서는 데이터 집중으로 인해 발생하는 네트워크의 에너지 낭비 및 전송 데이터의 정확도 문제를 해결하기 위해 자체조직지도(Self Organized Map, SOM)를 기반으로 한 클러스터링 기법을 제안한다. 결과적으로 제안된 기법을 통하여 클러스터링 된 노드들은 다른 클러스터링 기법과 비교했을 때 밀도 기반의 정확한 예측 값을 얻을 수 있다.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.212-218
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• 2021

Low-power and Lossy Networks (LLNs) have become the common network infrastructure for a wide scope of Internet of Things (IoT) applications. For efficient routing in LLNs, IETF provides a standard solution, namely the IPv6 Routing Protocol for LLNs (RPL). It enables effective interconnectivity with IP networks and flexibly can meet the different application requirements of IoT deployments. However, it still suffers from different open issues, particularly in large-scale setups. These include the node unreachability problem which leads to increasing routing losses at RPL sink nodes. It is a result of the event of memory overflow at LLNs devices due to their limited hardware capabilities. Although this can be alleviated by the establishment of multi-sink topologies, RPL still lacks the support for effective load balancing among multiple sinks. In this paper, we address the need for an efficient multi-sink load balancing solution to enhance the performance of PRL in large-scale scenarios and alleviate the node unreachability problem. We propose a new RPL objective function, Multi-Sink Load Balancing Objective Function (MSLBOF), and introduce the Memory Utilization metrics. MSLBOF enables each RPL node to perform optimal sink selection in a way that insure better memory utilization and effective load balancing. Evaluation results demonstrate the efficiency of MSLBOF in decreasing packet loss and enhancing network stability, compared to MRHOF in standard RPL.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권6호
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• pp.1849-1876
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• 2022

Wireless Sensor Network (WSN) is considered as an integral part of the Internet of Things (IoT) for collecting real-time data from the site having many applications in industry 4.0 and smart cities. The task of nodes is to sense the environment and send the relevant information over the internet. Though this task seems very straightforward but it is vulnerable to certain issues like energy consumption, delay, throughput, etc. To efficiently address these issues, this work develops a cross-layer model for the optimization between MAC and the Network layer of the OSI model for WSN. A high value of duty cycle for nodes is selected to control the delay and further enhances data transmission reliability. A node measurement prediction system based on the Kalman filter has been introduced, which uses the constraint based on covariance value to decide the scheduling scheme of the nodes. The concept of duty cycle for node scheduling is employed with a greedy data forwarding scheme. The proposed Duty Cycle-based Greedy Routing (DCGR) scheme aims to minimize the hop count, thereby mitigating the energy consumption rate. The proposed algorithm is tested using a real-world wastewater treatment dataset. The proposed method marks an 87.5% increase in the energy efficiency and reduction in the network latency by 61% when validated with other similar pre-existing schemes.

• Journal of Information Processing Systems
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• 제18권1호
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• pp.115-129
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• 2022

Adopting Internet of Things (IoT)-based technologies in smart homes helps users analyze home appliances electricity consumption for better overall cost monitoring. The IoT application like smart home system (SHS) could suffer from large missing values gaps due to several factors such as security attacks, sensor faults, or connection errors. In this paper, a novel framework has been proposed to predict large gaps of missing values from the SHS home appliances electricity consumption time-series datasets. The framework follows a series of steps to detect, predict and reconstruct the input time-series datasets of missing values. A hybrid convolutional neural network-long short term memory (CNN-LSTM) neural network used to forecast large missing values gaps. A comparative experiment has been conducted to evaluate the performance of hybrid CNN-LSTM with its single variant CNN and LSTM in forecasting missing values. The experimental results indicate a performance superiority of the CNN-LSTM model over the single CNN and LSTM neural networks.

• 드라이브 ㆍ 컨트롤
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• 제20권1호
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• pp.41-47
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• 2023

The aim of this study was to develop a method for installing strain gauges on moving, lubricating oil-filled, and sealed parts, such as drive shafts of equipment, including construction machinery. A measuring device was constructed using an embedded CPU and an IoT sensor to measure the strain of the strain gauge, which allowed for the measurement of axial torque and axial force, and subsequent analysis. To verify the performance of the developed device, the axial torque and axial force of the forklift were measured during operation using a strain gauge attached to the inside of the drive shaft. This study confirmed the possibility of measuring and analyzing the strain of a moving part, such as the inside of a drive shaft, which is sealed and filled with hydraulic oil.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2020년도 추계학술발표대회
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• pp.292-295
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• 2020

현대 사회에 들어서 급속도로 발달한 대중교통 서비스와 위치 정보시스템을 이용하여 사람들은 손쉽게 목적지로 이동할 수 있다. 최근 들어 네트워크를 이용하여 위치 정보를 제공하고 있지만 네트워크 취약계층과 같은 교통약자에게 이러한 서비스는 큰 효용이 없다. 본 논문에서는 위치 정보에 기반을 둔 대중 버스의 도착 정보와 거리측정 센서를 장착한 버스 알리미 단말 시스템을 제안한다. 제안한 시스템을 활용하여 대중교통 이용에 있어 소외된 교통약자에게 더욱 편리하고 접근성 높은 서비스를 제공할 수 있기를 기대한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3003-3029
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• 2023

The rapid evolution of the IoT has paved the way for new opportunities in smart city domains, including e-health, smart homes, and precision agriculture. However, this proliferation of services demands effective SLAs between customers and service providers, especially for critical services. Difficulties arise in maintaining the integrity of such agreements, especially in vulnerable wireless environments. This study proposes a novel SLA management model that uses an SDN-Enabled WSN consisting of wireless nodes to interact with smart contracts in a straightforward manner. The proposed model ensures the persistence of network metrics and SLA provisions through smart contracts, eliminating the need for intermediaries to audit payment and compensation procedures. The reliability and verifiability of the data prevents doubts from the contracting parties. To meet the high-performance requirements of the blockchain in the proposed model, low-cost algorithms have been developed for implementing blockchain technology in wireless sensor networks with low-energy and low-capacity nodes. Furthermore, a cryptographic signature control code is generated by wireless nodes using the in-memory private key and the dynamic random key from the smart contract at runtime to prevent tampering with data transmitted over the network. This control code enables the verification of end-to-end data signatures. The efficient generation of dynamic keys at runtime is ensured by the flexible and high-performance infrastructure of the SDN architecture.

• 한국농공학회논문집
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• 제66권3호
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• pp.53-62
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• 2024

The purpose of this study is to examine the methodology for applying digital twin technology to pumping station, identify the factors to be determined at each stage, and present its applicability. When analyzing the requirements for developing a digital twin for pumping station, they were categorized into service requirements, IoT device requirements, and gateway requirements, with a total of 39 requirements established. In system design, it was structured according to the principles of modularity, abstraction, stepwise decomposition, and information hiding, allowing the implementation of planned items for diagnosis and operational management. There are difficulties in setting communication-related protocols and applying them in the field due to the complexity of overseeing the entire system with data. Therefore, it is necessary to clarify the purpose of the system, and there are challenges in identifying the characteristics of individual facilities, such as pumps in pumping station, and fully incorporating them into the system process. Thus, the framework of the initial design is crucial for implementing a digital twin.

• 한국정보통신학회논문지
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• 제21권6호
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• pp.1121-1126
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• 2017

최근 스마트 게이트웨이의 중요성이 커지고 있다. 유무선 공유기와 라우터 같은 네트워크 기능이 복합 내재되어 있다. 사물인터넷 시장이 확대되면서 네트워크 안정성과 보안문제가 발생했고 이러한 보안 문제를 해결할 방법 중 하나로 VPN 기술이 제시 되었다. 회선품질이 나쁜 SOHO 환경에서 VPN 구현을 위해서는 효율적인 설계가 필요하다. 본 논문에서는 OpenWRT기반으로 개발한 사물인터넷 지원 스마트 게이트웨이에서 VPN 터널링의 구현방법과 인터넷 회선 상황에 따른 실시간 트래픽 쉐이핑 방법에 대해 개념 및 원리를 제시하며 이에 대한 구현 및 측정한 성능지표를 제시한다.