• Journal of the Korea Society of Computer and Information
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• v.20 no.11
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• pp.39-46
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• 2015

In this paper, we propose a performance-aware workload model for efficient implementation of control systems. When implementing a control algorithm as an embedded computer system, the control code executes periodically. For such systems, its control performance depends on not only the accuracy of the control algorithm itself but also temporal parameters such as control period and sensing to actuation delay. In this regard, this paper studies the relation between control period and delay by measuring and analyzing the control performance of LKAS (Lane Keeping Assist System) with varying period and delay combinations. Through this experimental study, this paper shows that the two timing parameters, i.e.,control period and delay, has a tradeoff relation in terms of control performance.

• Information and Communications Magazine
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• v.30 no.10
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• pp.79-85
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• 2013

By interacting with external wireless sensors, smartphones can gather high-fidelity data on the surrounding environment to develop various environment-aware, personalized applications. In this work we introduce the sensor virtualization module (SVM), which virtualizes external sensors so that smartphone applications can easily utilize a large number of external sensing resources. Implemented on the Android platform, our SVM simplifies the management of external sensors by abstracting them as virtual sensors to provide the capability of resolving conflicting data requests from multiple applications and also allowing sensor data fusion for data from different sensors to create new customized sensors elements. We envision our SVM to open the possibilities of designing novel personalized smartphone applications.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.225-234
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• 2012

In Wireless Sensor Networks (WSNs) where deployed sensors are not stationary, the most important demand of is to design a cost effective and reliable network. This paper proposes an energy aware network construction and routing scheme, which is based on the hierarchical approach to distribute the task in some sensors in order to prolong the network lifetime. It aims to make even the energy consumption on constitute nodes. With the node hierarchy, the sink initiates the construction by electing gateway nodes in the network and the elected gateway nodes participate to form logical clusters by electing a cluster head in each cluster. Then, the cluster heads aggregate data from the sensing sensors and transmit the data to the sink through the gateway. Our simulation result illustrates that the proposed scheme provides a basement to reduce the source of energy dissipation in network construction, and as well as in data routing.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.12
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• pp.1051-1061
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• 2005

This paper proposes a ubiquitous robot, Ubibot, as an integration of three forms of robots: Software robot (Sobot), Embedded robot (Embot) and Mobile robot (Mobot). A Sobot is a virtual robot, which has the ability to move to any place or connect to any device through a network in order to overcome spatial limitations. It has the capacity to interpret the context and thus interact with the user. An Embot is embedded within the environment or within physical robots. It can recognize the locations of and authenticate the user or robot, and synthesize sensing information. Also it has the ability to deliver essential information to the user or other components of Ubibot by using various types of output devices. A Mobot provides integrated mobile service. In addition, Middleware intervenes different protocols between Sobot, Embot, and Mobot in order to incorporate them reliably. The services provided by Ubibot will be seamless, calm and context-aware based on the combination of these components. This paper presents the basic concepts and structure of Ubibot. A Sobot, called Rity, is introduced in order to investigate the usability of the proposed concepts. Rity is a 3D synthetic character which exists in the virtual world, has a unique IP address and interacts with human beings through Vision Embot, Sound Embot, Position Embot and Voice Embot. Rity is capable of moving into a Mobot and controlling its mobility. In doing so, Rity can express its behavior in the virtual world, for example, wondering or moving about in the real world. The experimental results demonstrate the feasibility of implementing a Ubibot in a networked environment.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.56-61
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• 2017

Recently, the satellite development project in Korea has been changing from demand to focus on various purposes. Especially, it is proposed to process satellite data from a simple terrestrial image observation satellite and to produce high value added information. In order to expand demand for satellite information, it is necessary to develop customized information and to provide information that reflects the needs of the final target population. In this study, we conducted a questionnaire survey and analyzed the results to analyze the requirements for the customized services of environmental satellites. As a result, the environmental satellites were found to have a low awareness due to the launch and operation, but they were highly aware of the recent environmental issues such as fine dust. In addition, they are aware of the necessity of developing independent environmental satellites because they have a strong desire for environmental security, and they prefer to provide materials through media that are easy to publicize and access through the media.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.93-96
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• 2015

In this paper, we introduce a fire detection system using context-aware sensor. In existing weather and based on vision sensor of fire detection system case, acquired image through sensor of camera is extracting features about fire range as processing to convert HSI(Hue, Saturation, Intensity) model HSI which is color space can have durability in illumination changes. However, in this case, until a fire occurs wide range of sensing a fire in a single camera sensor, it is difficult to detect the occurrence of a fire. Additionally, the fire detection in complex situations as well as difficult to separate continuous boundary is set for the required area is difficult. In this paper, we propose an algorithm for real-time by using a temperature sensor, humidity, Co2, the flame presence information acquired and comparing the data based on multiple conditions, analyze and determine the weighting according to fire it. In addition, it is possible to differential management to intensive fire detection is required zone dividing the state of fire.

• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1779-1785
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• 2018

In this paper, we propose an error correction method to improve the accuracy of human activity recognition using sensor event data obtained by smart devices such as wearable and smartphone. In the context awareness through the smart device, errors inevitably occur in sensing the necessary context information due to the characteristics of the device, which degrades the prediction performance. In order to solve this problem, we apply Kalman filter's error correction algorithm to compensate the signal values obtained from 3-axis acceleration sensor of smart device. As a result, it was possible to effectively eliminate the error generated in the process of the data which is detected and reported by the 3-axis acceleration sensor constituting the time series data through the Kalman filter. It is expected that this research will improve the performance of the real-time context-aware system to be developed in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4883-4901
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• 2016

Energy efficiency in Wireless Sensor Networks (WSNs) is very appealing research area due to serious constrains on resources like storage, processing, and communication power of the sensor nodes. Due to limited capabilities of sensing nodes, such networks are composed of a large number of nodes. The higher number of nodes increases the overall performance in data collection from environment and transmission of packets among nodes. In such networks the nodes sense data and ultimately forward the information to a Base Station (BS). The main issues in WSNs revolve around energy consumption and delay in relaying of data. A lot of research work has been published in this area of achieving energy efficiency in the network. Various techniques have been proposed to divide such networks; like grid division of network, group based division, clustering, making logical layers of network, variable size clusters or groups and so on. In this paper a new technique of group based WSNs is proposed by using some features from recent published protocols i.e. "Energy-Efficient Multi-level and Distance Aware Clustering (EEMDC)" and "Energy-Efficient Multi-level and Distance Aware Clustering (EEUC)". The proposed work is not only energy-efficient but also minimizes the delay in relaying of data from the sensor nodes to BS. Simulation results show, that it outperforms LEACH protocol by 38%, EEMDC by 10% and EEUC by 13%.

• Journal of the Korean housing association
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• v.26 no.4
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• pp.55-62
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• 2015

The international concern on the inhalable fine dust is continuing to increase. In addition to the toxic properties of the fine dust itself, it can be more dangerous than other environmental factors since the dust pollution is hard to be detected by human sense. Although the information on outdoor air condition can be acquired easily, the indoor dust concentration is another problem because the indoor air condition is influenced by the architectural environment and human activity. It means occupants may be exposed to indoor dust pollution over a long period without being aware. Therefore the indoor dust concentration should be measured separately and visualized as an intuitive information. By visualizing, the indoor dust concentration in each space can be recognized practically in compare with the degree of pollution in adjacent spaces. Besides the visualization outcome can be used as base data for related research such as an analysis of the relation between indoor dust concentration and architectural environment. Meanwhile, with the development of network and micro sensing devices, it became possible to collect wide range of indoor environment data. In this regards, this paper suggests a system for visualization of indoor dust concentration and demonstrates it on an actual space.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.4
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• pp.243-249
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• 2016

Energy-harvesting nodes in wireless sensor networks(WSNs) can be exhausted due to a heavy workload even though they can harvest energy from their environment. On contrast, they can sometimes fully charged, thus waste the harvested energy due to the limited battery-capacity. In order to utilize the harvested energy efficiently, we introduce a selective data compression and transmission range control scheme for energy-harvesting nodes. In this scheme, if the residual energy of a node is expected to run over the battery capacity, the node spends the surplus energy to exploit the data compression or the transmission range expansion; these operations can reduce the burden of intermediate nodes at the expanse of its own energy. Otherwise, the node performs only basic operations such as sensing or transmitting so as to avoid its blackout time. Simulation result verifies that the proposed scheme gathers more data with fewer number of blackout nodes than other schemes by consuming energy efficiently.