• Advances in nano research
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• v.9 no.3
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• pp.133-145
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• 2020

In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.44-45
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• 2022

The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) has been developing the S-201 Aids to Navigation information standard since 2019 for the purpose of exchanging Aids to Navigation data. In this study, the navigation information managed in Korea was modeled using the IALA S-201 navigation information standard system for the management and service of smart navigation. By using the S-201 Aids to Navigation information standard system, the basis for reflecting the information standard system was prepared in the production, exchange, and collection of domestic navigational data. It also intends to contribute to the establishment of an information exchange system between the Aids to Navigation organization, IALA, and countries.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.473-480
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• 2019

The smart home is a technology that can monitor and control by connecting everything to a communication network in various fields such as home appliances, energy consumers, and security devices. The Smart home is developing not only automatic control but also learning situation and user's taste and providing the result accordingly. This paper proposes a model that can provide a comfortable indoor environment control service for the user's characteristics by detecting the user's behavior as well as the automatic remote control service. The whole system consists of ESP 8266 with sensor and Wi-Fi, Firebase as a real-time database, and a smartphone application. This model is divided into functions such as learning mode when the home appliance is operated, learning control through learning results, and automatic ventilation using indoor and outdoor sensor values. The study used moving averages for temperature and humidity in the control of home appliances such as air conditioners, humidifiers and air purifiers. This system can provide higher quality service by analyzing and predicting user's characteristics through various machine learning and deep learning.

• Journal of information and communication convergence engineering
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• v.18 no.1
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• pp.61-68
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• 2020

In the era of the fourth industrial revolution, many production plants are gradually evolving into smart factories that apply information and communication technology to manufacturing, distribution, production, and quality management. The conversion from conventional factories to smart factories has resulted in the automation of production sites using the internet and the internet of things (IoT) technology. Thus, labor-intensive production can easily collect necessary information. However, implementing a smart factory required a significant amount of time, effort, and money. In particular, labor-intensive production industries are not automated, and productivity is determined by human skill. A representative industry of such industries is sewing the industry. In the sewing industry, wherein productivity is determined by the operator's skills. This study suggests that production performance, inventory management and product delivery of the sewing industries can be managed efficiently with existing production method by using smart buttons incorporating IoT functions, without using automated machinery.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.542-546
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• 2007

In the vision of ubiquitous computing environment, smart objects would communicate each other and provide many kinds of information about user and their surroundings in the home. This information enables smart objects to recognize context and to provide active and convenient services to the customers. However in most cases, context-aware services are available only with expert systems. In this paper, we present generalized activity recognition application in the smart home based on a naive Bayesian network(BN) and fuzzy clustering. We quantize continuous sensor data with fuzzy c-means clustering to simplify and reduce BN's conditional probability table size. And we apply mutual information to learn the BN structure efficiently. We show that this system can recognize user activities about 80% accuracy in the web based virtual smart home.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.87-90
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• 2011

Smart Grid는 전기 공급자와 수요자를 이어주는 전기 네트워크를 설치하여, 전기기기와 IT기술이 융합된 형태로 사용자내에서 Bluetooth, Zigbee를 이용한 전기기기를 통제하는 효율적인 에너지 네트워크의 일종이다. 하지만 Bluetooth, Zigbee는 인증과 키관리 문제가 있어 보안의 문제가 일어날 수 있다. 본 논문에서는 스마트 그리드에서 사용될 전기IT기기를 응용하여 제어하는 Bluetooth, Zigbee의 인증과 키관리, 키 생성 프로토콜을 통한 보안성 문제를 연구한다. 또한 Bluetooth, Zigbee에 대한 키 생성 프로토콜을 연구한다. 본 연구는 Smart Grid 시스템의 보안성과 안전성을 강화하여 Smart Grid 기술 발전에 기여할 것이다.

• The Journal of Economics, Marketing and Management
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• v.10 no.6
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• pp.17-26
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• 2022

Purpose: This study analyzes advanced cases of overseas smart cities and examines policy implications related to the creation of smart cities in Korea. Research design, data, and methodology: Analysis standards were established through the analysis of best practices. Analysis criteria include Technology, Privacy, Security, and Governance. Results: In terms of technology, U-City construction experience and communication infrastructure are strengths. Korea's ICT technology is inferior to major countries. On the other hand, mobile communication, IoT, Internet, and public data are at the highest level. The privacy section created six principles: legality, purpose limitation, transparency, safety, control, and accountability. Security issues enable urban crime, disaster and catastrophe prediction and security through the establishment of an integrated platform. Governance issues are handled by the Smart Special Committee, which serves as policy advisory to the central government for legal system, standardization, and external cooperation in the district. Conclusions: Private technology improvement and participation are necessary for privacy and urban security. Citizens should participate in smart city governance.

• Smart Structures and Systems
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• v.3 no.4
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• pp.475-494
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• 2007

This paper deals with the development of an innovative distributed construction system based on smart prefabricated concrete elements for the real-time condition assessment of civil infrastructure. So far, two reduced-scale prototypes have been produced, each consisting of a $0.2{\times}0.3{\times}5.6$ m RC beam specifically designed for permanent instrumentation with 8 long-gauge Fiber Optic Sensors (FOS) at the lower edge. The sensing system is Fiber Bragg Grating (FBG)-based and can measure finite displacements both static and dynamic with a sample frequency of 625 Hz per channel. The performance of the system underwent validation in the laboratory. The scope of the experiment was to correlate changes in the dynamic response of the beams with different damage scenarios, using a direct modal strain approach. Each specimen was dynamically characterized in the undamaged state and in various damage conditions, simulating different cracking levels and recurrent deterioration scenarios, including cover spalling and corrosion of the reinforcement. The location and the extent of damage are evaluated by calculating damage indices which take account of changes in frequency and in strain-mode-shapes. The outcomes of the experiment demonstrate how the damage distribution detected by the system is fully compatible with the damage extent appraised by inspection.

• Korean System Dynamics Review
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• v.16 no.3
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• pp.97-107
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• 2015

본 논문은 최근 다양한 사회 분야에 있어서 IT 기술이 적용되는 과정을 SD 모델링 방식을 사용하여 연구한 경험과 발견을 서술하고자 한다. 모델의 초기 단계에서 우리는 다양한 사회 분야마다 다른 SD 모델을 만들 것이냐 아니면 기본적으로 유사한 모델 구조를 취할 것이냐를 선택해야 했다. 사회 분야마다 다른 구조의 SD 모델을 만들면, 상호간의 구조와 시뮬레이션 결과를 비교하기 어렵다. 하지만 상호 모델 구조를 유사하게 구축하려고 하니, 서로 다른 모델링 팀들간의 의사소통에 노력과 시간 소비가 지나치게 커져 갔다. 이러한 어려움을 극복하기 위하여 본 연구에서는 시스템 다이내믹스 모델링에도 시스템 사고의 원형적 피드백 루프에서와 같은 원형적 SD 모델을 만들고, 이를 사회 각 분야에 적용하는 방식을 취하고자 하였다. 먼저 최근 IT 기술 발전을 이끌어 가는 핵심적인 요소로서 클라우드 컴퓨팅, 스마트 기기, 사물 인터넷을 선정하고 이들간의 상호 관계성을 표현하는 SD 모델을 만들었다. 이를 원형(archetype)으로 하여, 교육, 의료, 원격 근무 등 사회 각 분야의 IT 확산 과정에 적용하여 모델링을 하고 시뮬레이션을 하여 상호 비교하면서 정책 시사점을 논의할 수 있었다. 본 논문에서는 이 중에서 원격 근무(smart work)에 관한 적용 사례를 제시함으로써, SD 모델링에 있어서 원형적 접근 방법의 가능성을 탐색한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.3
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• pp.547-560
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• 2014

Smart Grid, which maximize the efficiency of energic utilization by applying Information and Communication Technology to Power Grid, requires high availability. Attacks, such as DDoS, which cause suspension of service and lead to social disruptions have recently been increasing so that systematic management over availability becomes more important. In this paper, we presents a new evaluation criteria of Korean Smart Grid by comparing availability assessment items of international standards specified in management system and then overcome the limitations of availability evaluation of existing information security management system.