• Journal of Information Processing Systems
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• v.12 no.1
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• pp.73-82
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• 2016

In cognitive radio networks (CRNs), the performance of the transmission control protocol (TCP) at the secondary user (SU) severely drops due to the mistrigger of congestion control. A long disruption is caused by the transmission of primary user, leading to the mistrigger. In this paper, we propose a cross-layer approach, called a CR-aware scheme that enhances TCP performance at the SU. The scheme is a sender side addition to the standard TCP (i.e., TCP-NewReno), and utilizes an explicit cross-layer signal delivered from a physical (or link) layer and the signal gives an indication of detecting the primary transmission (i.e., transmission of the primary user). We evaluated our scheme by implementing it onto a software radio platform, the Universal Software Radio Peripheral (USRP), where many parts of lower layer operations (i.e., operations in a link or physical layer) run as user processes. In our implementation, we ran our CR-aware scheme over IEEE 802.15.4. Furthermore, for the purpose of comparison, we implemented a selective ACK-based local recovery scheme that helps TCP isolate congestive loss from a random loss in a wireless section.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.436-439
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• 2005

As mobile computers and embedded systems are becoming popular recently, we need to study how to utilize the resources such as power, space, CPU clocks, and memory efficiently. In traditional embedded system development, we were interested in resource usage based on hardware but, as software is becoming more important, we need to study how to analyze the resource usage based on software. In this research, we propose a new method called 'Instruction Level Resource Usage Analysis Method' and implement it as a resource usage analysis tool called 'I-Debugger'. I-Debugger is constructed on three layers: debugging layer which controls the execution of software on instruction level, statistic layer which gathers real-time data and convert to useful information, and analysis layer which generate useful information to specific applications. We have applied the debugger to some simple problem and found that our method is useful in developing resource efficient embedded systems.

• Journal of Internet of Things and Convergence
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• v.9 no.2
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• pp.71-76
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• 2023

In this paper, we propose a smoothed received signal strength indicator (RSSI)-based distance estimation using deep neural network (DNN) for accurate distance estimation in an environment where a single receiver is used. The proposed scheme performs a data preprocessing consisting of data splitting, missing value imputation, and smoothing steps to improve distance estimation accuracy, thereby deriving the smoothed RSSI values. The derived smoothed RSSI values are used as input data of the Multi-Input Single-Output (MISO) DNN model, and are finally returned as an estimated distance in the output layer through input layer and hidden layer. To verify the superiority of the proposed scheme, we compared the performance of the proposed scheme with that of the linear regression-based distance estimation scheme. As a result, the proposed scheme showed 29.09% higher distance estimation accuracy than the linear regression-based distance estimation scheme.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.337-341
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• 1991

Fieldbus is a low level serial digital network which will be used for factory automation. This paper describes lower layer implementation of a Fieldbus network interface. Physical layer provides hardware interface between IBM-PC and Fieldbus. Also, physical layer uses manchester coding, shielded twisted pair lines and RS-485 electrical standard. Data link layer includes Intel's iDCX96 real time executive for 8797 one chip microcontroller and Fieldbus data link protocol software.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.254-254
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• 2004

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.52-55
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• 2004

VMS (virtual manufacturing system) may be defined as a transparent interface/control mechanism to support human decision-making via simulation and monitoring of real operating situation through modeling of all activities in RMS (real manufacturing system). The three main layers in VMS are business process layer, manufacturing execution layer, and facility operation layer, and each layer is represented by a specific software system having its own input modeler module. The current version of these input modelers has been implemented based on its own 'local' framework, and as a result, there are no information sharing mechanism, nor a common user view among them. Proposed in this paper is a unified modeler framework covering the three VMS layers, in which the concept of PPR (product-process-resource) model is employed as a common semantics framework and a 2D graphic network model is used as a syntax framework. For this purpose, abstract class PPRObject and GraphicObject are defined and then a subclass is inherited from the abstract class for each application layer. This feature would make it easier to develop and maintain the individual software systems. For information sharing, XML is used as a common data format.

• The KIPS Transactions:PartA
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• v.12A no.7 s.97
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• pp.621-626
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• 2005

Recently, flash memory is widely used in various embedded applications since it has many advantages in terms of non-volatility, fast access speed, shock resistance, and low power consumption. However, it requires a software layer called FTL(Flash Translation Layer) due to its hardware characteristics. We present a new FTL algorithm named LSTAFF(Large State Transition Applied Fast flash Translation Layer) which is designed for large block flash memory The presented LSTAFF is adjusted to flash memory with pages which are larger than operating system data sector sizes and we provide performance results based on our implementation of LSTAFF and previous FTL algorithms using a flash simulator.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.9
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• pp.3870-3884
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• 2020

The proposed framework of Four Layer Robust Storage in Cloud (FLRSC) architecture involves host server, local host and edge devices in addition to Virtual Machine Monitoring (VMM). The goal is to protect the privacy of stored data at edge devices. The computational intelligence (CI) part of our algorithm distributes blocks of data to three different layers by partially encoded and forwarded for decoding to the next layer using hash and greed Solomon algorithms. VMM monitoring uses snapshot algorithm to detect intrusion. The proposed system is compared with Tiang Wang method to validate efficiency of data transfer with security. Hence, security is proven against the indexed efficiency. It is an important study to integrate communication between local host software and nearer edge devices through different channels by verifying snapshot using lamport mechanism to ensure integrity and security at software level thereby reducing the latency. It also provides thorough knowledge and understanding about data communication at software level with VMM. The performance evaluation and feasibility study of security in FLRSC against three-layered approach is proven over 2³² blocks of data with 98% accuracy. Practical implications and contributions to the growing knowledge base are highlighted along with directions for further research.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.367-370
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• 2002

In this paper, we propose a new node architecture LonWorh control Network for home network system environmint using power line communications. Using conventional Lon Work technology is a many disputable points for home network. LonWork network system needs high-cost development equipment. Moreover, conventional Lon Work system can not implement high-grade algorithms and variety application operation. because of the limitation of processing ability in Neuron chip. For that reason, the proposed structure is applicable to low-cost and more complex applications which are impossible in home network using conventional Lonworks structure. The proposed structure is implemented with some hardware and かone software for power line home network. The physical layer and the MAC layer of the LonTalk protocol within ton Work are implemented in hardware, which decreases the development costs communication processor. The upper of link layer of the LonTalk protocol is implemented with software, which decreases the development costs of software and increases the flexibility of tile system and increases the extension of the system. We verified the commercial feasibility of the proposed system through the power line tests with the existing LonWorks network in home network. As a result, it is concluded that the proposed architecture provides increasing flexibility and decreasing cost of the system.

• The Journal of Korean Association of Computer Education
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• v.21 no.6
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• pp.27-37
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• 2018

In this paper, we propose a design and development method of an elevator simulator that can be used as an embedded application layer software learning tool and a teaching and learning method using it. The simulator provides students with an environment to implement the operating principle and control method of the elevator system in the application layer excluding the issues of hardware and embedded OS layer. This allows students to have a reactive and real-time embedded application development experience. In addition, we present a four-week embedded application software training course with hands-on exercises that add step-by-step functionality using a simulator. As a result of training for actual students, we obtained 83.3 points of learning achievement score and proved that the curriculum has a significant effect on embedded application learning.