• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.1
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• pp.55-61
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• 2020

Social infrastructure facilities that have been under construction since the country's high-growth period are undergoing rapid aging, and, thus, safety assessments of large structures such as bridge tunnels, which can be directly linked to large-scale casualties in the event of an accident, are necessary. It is difficult to construct economical and efficient wireless smart sensor networks that improve structural health monitoring (SHM) because the existing wire sensors have a short signal reach. However, low-power wide-area networks (LPWANs) are becoming popular within the Internet of Things, and enable economical and efficient SHM. In this study, the technology trends of a wireless measuring sensor based on LoRa LPWANs were investigated, and an installation and maintenance plan for this type of sensor is proposed.

• Wind and Structures
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• v.36 no.4
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• pp.237-247
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• 2023

The emergence of high-rise buildings has necessitated frequent structural health monitoring and maintenance for safety reasons. Wind causes damage and structural changes on tall structures; thus, safe structures should be designed. The pressure developed on tall buildings has been utilized in previous research studies to assess the impacts of wind on structures. The wind tunnel test is a primary research method commonly used to quantify the aerodynamic characteristics of high-rise buildings. Wind pressure is measured by placing pressure sensor taps at different locations on tall buildings, and the collected data are used for analysis. However, sensors may malfunction and produce erroneous data; these data losses make it difficult to analyze aerodynamic properties. Therefore, it is essential to generate missing data relative to the original data obtained from neighboring pressure sensor taps at various intervals. This study proposes a deep learning-based, deep convolutional generative adversarial network (DCGAN) to restore missing data associated with faulty pressure sensors installed on high-rise buildings. The performance of the proposed DCGAN is validated by using a standard imputation model known as the generative adversarial imputation network (GAIN). The average mean-square error (AMSE) and average R-squared (ARSE) are used as performance metrics. The calculated ARSE values by DCGAN on the building model's front, backside, left, and right sides are 0.970, 0.972, 0.984 and 0.978, respectively. The AMSE produced by DCGAN on four sides of the building model is 0.008, 0.010, 0.015 and 0.014. The average standard deviation of the actual measures of the pressure sensors on four sides of the model were 0.1738, 0.1758, 0.2234 and 0.2278. The average standard deviation of the pressure values generated by the proposed DCGAN imputation model was closer to that of the measured actual with values of 0.1736,0.1746,0.2191, and 0.2239 on four sides, respectively. In comparison, the standard deviation of the values predicted by GAIN are 0.1726,0.1735,0.2161, and 0.2209, which is far from actual values. The results demonstrate that DCGAN model fits better for data imputation than the GAIN model with improved accuracy and fewer error rates. Additionally, the DCGAN is utilized to estimate the wind pressure in regions of buildings where no pressure sensor taps are available; the model yielded greater prediction accuracy than GAIN.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.2
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• pp.113-120
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• 2015

Under the penetration of smartphones equipped with a variety of features grows globally, the efficient using of a variety of functions of smartphones has been increased. In accordance with this trend, a lot of researches on the remote control method using the smart phone for consumer products in home networks. Input methods of the current smpartphoes are typically button-based inputs through touching. The button input methods are inconvenient for people who are not familiar touch. Therefore, the researches on the different input schemes to replace the touch methods are required. In this paper, we propose a gesture based input method to replace the touch-sensitive input that of the existing smartphone applications, and a way to apply it to home networks. The proposed method uses three-axis acceleration sensor which is built into smatphones, and it also defines six kinds of gestures patterns that may be applied to home network systems by measuring the recognition rates.

• Journal of Korean Society of Disaster and Security
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• v.9 no.1
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• pp.19-24
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• 2016

In this study, we conducted a study on the development of Internet of Things-based disaster response system. We researched the method of building the network-based disaster prevention system using a client machine that the sensor network and the keeper. Also, we developed the algorithm for optimal evacuation shelter based on spanning tree algorithm. The system is tested actually in Seoul Gaepo station, and we verified the usability of the system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.838-839
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• 2016

IEEE 802.15.4 is the standard wireless link technology for low power, low cost, but long lifetime applications including wireless sensor network (WSN). Currently, whether or not IP architecture should be used in WSN over its 802.15.4 link is under dispute. Such kind of arguments may last for a long time without some convincing experimental measurements of real case performances of IP over 802.15.4 implementation, and thus prevent the advance of related research. In RFC4944, IETF proposed the 6LoWPAN specification to enable IPv6 communication over low power, wireless personal area networks. We try to alleviate the dispute and make the direction clearer to the community so as to promote further valuable research in this topic.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.296-299
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• 2022

The rapid urban expansion and the increase in natural disasters due to the increase of population after industrialization and climate change are causing numerous urban management problems. The IP based hyper-connectivity caused by the initiation of the 4th industrial revolution enables a variety of technologies and services that produce vast amounts of data and solve urban management problems based on this. Especially, the quality of life is improved by providing the necessary information for life that are produced through a sensor network on wired and wireless communication. In this study, we intend to propose the method of optimal communcation network composition for innovative and futuristic city management technology through the case of K-water Smart Village Communication System

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.8 no.4
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• pp.288-298
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• 2008

We introduce new type of networked robot, Ubiquitous Robotic Companion (URC), embedded with ATLAS Service-oriented architecture for enhancing the space sensing capability. URC is a network-based robotic system developed by ETRI. For years of experience in deploying service with ATLAS sensor platform for elder and people with special needs in smart houses, we need networked robots to assist elder people in their successful daily living. Recently, pervasive computing technologies reveals possibilities of networked robots in smart spaces, consist of sensors, actuators and smart devices can collaborate with the other networked robot as a mobile sensing platform, a complex and sophisticated actuator and a human interface. This paper provides our experience in designing and implementing system architecture to integrate URC robots in pervasive computing environments using the University of Florida's ATLAS service-oriented architecture. In this paper, we focus on the integrated framework architecture of URC embedded with ATLAS platform. We show how the integrated URC system is enabled to provide better services which enhance the space sensing of URC in the smart space by applying service-oriented architecture characterized as flexibility in adding or deleting service components of Ubiquitous Robotic Companion.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.6
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• pp.482-490
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• 2023

With the advent of the Fourth Industrial Revolution, many companies are developing Smart Ships to enable autonomous navigation, unmanned operation, and cost-effective shipping. In order to facilitate the operation of these Smart Ships, significant emphasis is being placed on improving external communication capabilities and developing autonomous navigation systems. Moreover, unmanned ship operation necessitates replacing of all visually observed conditions with sensors, leading to an inevitable increase in the number of sensors and actuators compared to traditional methods. However, in South Korea, the communication network for sensors and actuators primarily relies on the conventional 1:1 hardwired wiring, with the use of higher-level communication networks when necessary. Therefore, in this paper, we introduce the AS-Interface protocol, which is used for monitoring and controlling sensors and actuators, with the expectation that it will greatly contribute to the development of future Smart Ships by reducing production time, costs, and maintenance duration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.133-135
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• 2015

This paper is about the design of flowerpot management system which allows you to manage the flowerpot more efficiently and conveniently using Internet of Things when you start to grow plants. IoT connects all things to the network to provide various services to users, it has recently been focused on the center of the IT convergence techniques. So by using the realization sensor based IoT technology the need for research and development of IoT technologies were designed for the system. Basically, Device is using soil humidity sensor and Arduino, Android smart phone and smart light bulb. Transmit the humidity value of the flowerpot that measured by the sensor in a wireless communication, by controlling the state according to the value of the humidity, users can be provided a visual information and set up a flowerpot management and plan.

• Smart Structures and Systems
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• v.6 no.8
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• pp.939-951
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• 2010

A low-cost wireless sensor network (WSN) solution with highly expandable super and simple nodes was developed. The super node was designed as a sensing unit as well as a receiving terminal with low energy consumption. The simple node was designed to serve as a cheaper alternative for large-scale deployment. A 12-bit ADC inputs and DAC outputs were reserved for sensor boards to ease the sensing integration. Vibration and thermal field tests of the Chi-Lu Bridge were conducted to evaluate the WSN's performance. Integral acceleration, temperature and tilt sensing modules were constructed to simplify the task of long-term environmental monitoring on this bridge, while a star topology was used to avoid collisions and reduce power consumption. We showed that, given sufficient power and additional power amplifier, the WSN can successfully be active for more than 7 days and satisfy the half bridge 120-meter transmission requirement. The time and frequency responses of cables shocked by external force and temperature variations around cables in one day were recorded and analyzed. Finally, guidelines on power characterization of the WSN platform and selection of acceleration sensors for structural health monitoring applications were given.