• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.889-896
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• 2007

Advances in wireless networking, micro-fabrication and integration, and embedded microprocessors have enabled a new generation of massive-scale sensor networks. Because each sensor node is limited in size and capacity, it is very important to design a new simple and energy efficient protocol. Among conventional sensor networks' routing protocols, the directed diffusion scheme is widely blown because of its simplicity. This scheme, however, has a defect in that sending interest and exploratory data messages while setting connection paths consumes much energy because of its flooding scheme. Therefore, this paper proposes a new sensor network routing protocol, called sequenced directed diffusion with a threshold control, which compromises the conventional directed diffusion scheme's defect and offers an energy efficient routing idea. With a computer simulation, its performance is evaluated and compared to the conventional directed diffusion scheme. Numerical results show that the proposed scheme offers energy efficiency while routing packets, and resolves ill-balanced energy consumption among sensor nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.5
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• pp.863-869
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• 2008

In this paper, a system with sensor network security mechanism which can be applied to home network structure is designed and it is implemented on a virtual network of a home network middleware. The basic structure of home networking middleware supports one-to-one (unicast) or broadcast communication mode between the lookup server and service nodes on the network. Confidentiality and authentication are key security factors of the one-to-one communication and user authentication is crucial for broadcasting mode. One of the sensor network's security techniques SPINS consists of SNEP and ${\mu}TESLA$. The SNEP ensures confidentiality and authentication, and ${\mu}TESLA$ provides broadcast authentication. We propose a SPIN based home network middleware and it is implemented by using the CBC-MAC for MAC generation, the counter mode (CTR) for message freshness, the pseudo random function (PRF) and RC5 as encryption algorithm. The implementation result shows that an attacker cannot decrypt the message though he gets the secure key because of CTR mode. In addition, we confirmed that a received message of the server is authenticated using MAC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1442-1449
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• 2007

Shadows are important elements for realistic rendering of the 3D scene. We cannot recognize the distance of objects in the 3D scene without shadows. Two methods, image-based medthods and object-based methods, are largely used for the rendering of shadows. Object based methods can generate accurate shadow boundaries. However, it cannot be used to generate the realtime shadows because the time complexity defends on the complexity of the 3D scene. Image based methods which are techniques to generate shadows are widely used because of fast calculation time. However, this algorithm has aliasing problems. PCF is a method to solve the aliasing problem. Using PCF technique, antialiased shadow boundaries can be generated. However, PCF with large filter size requires more time to calculate antialiased shadow boundaries. This paper proposes an improved PCF technique which generates antialiased shadow boundaries similar to that of PCF. Compared with PCF, this technique can generate antialiased shadows in less time.

• Journal of the Korea Society for Simulation
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• v.29 no.3
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• pp.9-18
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• 2020

The development of a large-scale thermal power plant control simulator consists of water/steam systems, air/combustion systems, pulverizer systems and turbine/generator systems. Modeling is possible for all systems except mechanical turbines/generators. Currently, there have been attempts to develop neural network simulators for some systems of a boiler, but the development of simulator for the whole system has never been completed. In particular, autoTuning, one of the key technology developments of all power generation companies, is a technology that can be achieved only when modeling for all systems with high accuracy is completed. The simulation results show accuracy of 95 to 99% or more of the actual boiler system, so if the field PID controller is fitted to this simulator, it will be available for fault diagnosis or auto-tuning.

• Journal of Broadcast Engineering
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• v.26 no.2
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• pp.167-174
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• 2021

Recently, deep learning technology is widely used in various computer vision applications, such as object recognition, classification, and image generation. In particular, the deep learning-based super-resolution has been gaining significant performance improvement. Fast super-resolution convolutional neural network (FSRCNN) is a well-known model as a deep learning-based super-resolution algorithm that output image is generated by a deconvolutional layer. In this paper, we propose an FPGA-based convolutional neural networks accelerator that considers parallel computing efficiency. In addition, the proposed method proposes Optimal-FSRCNN, which is modified the structure of FSRCNN. The number of multipliers is compressed by 3.47 times compared to FSRCNN. Moreover, PSNR has similar performance to FSRCNN. We developed a real-time image processing technology that implements on FPGA.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.719-728
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• 2019

Recently, there has been a growing market for shared mobility businesses that share 'transport' such as cars and bikes, and many operators offer a variety of services. However, if the fare can not be charged normally because of security vulnerability, the operator can not continue the business. So there should be no security loopholes. However, there is a lack of awareness and research on shared mobility security. In this paper, we analyzed security vulnerabilities exposed in application log of shared bike service in Korea. We could easily obtain the password of the bike lock and the encryption key of the AES-128 algorithm through the log, and confirmed the data generation process for unlocking using software reverse engineering. It is shown that the service can be used without charge with a success rate of 100%. This implies that the importance of security in shared mobility business and new security measures are needed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.211-223
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• 2018

Mobile relay systems have been adopted by $4^{th}$ generation mobile systems as an alternative method to extend cell coverage as well as to enhance the system throughput at cell-edges. In order to achieve such performance gains, the mobile relay systems require path selection and resource allocation schemes that are specifically designed for these systems which make use of additional radio resources not needed in single-hop systems. This paper proposes an integrated path selection and resource allocation scheme for LTE-Advanced relay systems using collaborative communication. We first define the problem of maximizing the downlink throughput of LTE-Advanced relay systems using collaborative communication and transform it into a multi-dimensional multi-choice backpacking problem. The proposed Lagrange multiplier-based heuristic algorithm is then applied to derive the approximate solution to the maximization problem. It is shown through simulations that the approximate solution obtained by the proposed scheme can achieve a near-optimal performance.

• Journal of the Korean Society for information Management
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• v.36 no.3
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• pp.131-148
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• 2019

This study constructed a cognitive model of information processing to understand the topic of a sound material and its characteristics. It then proposed methods to generate sound summaries, by incorporating anterior-posterior N400/P600 components of event-related potential (ERP) response, into the language representation of the cognitive model of information processing. For this end, research hypotheses were established and verified them through ERP experiments, finding that P600 is crucial in screening topic-relevant shots from topic-irrelevant shots. The results of this study can be applied to the design of classification algorithm, which can then be used to generate the content-based metadata, such as generic or personalized sound summaries and video skims.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.207-213
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• 2019

Recently, the importance for internet of things (IoT) security has increased enormously and hardware-based compact chips are needed in IoT communication industries. In this paper, we propose low-complexity crypto-processor that unifies advanced encryption standard (AES), academy, research, institute, agency (ARIA), and CLEFIA protocols into one combined design. In the proposed crypto-processor, encryption and decryption processes are shared, and 128-bit round key generation process is combined. Moreover, the shared design has been minimized to be adapted in generic IoT devices and systems including lightweight IoT devices. The proposed crypto-processor was implemented in Verilog hardware description language (HDL) and synthesized to gate level circuit in 65nm CMOS process, which results in 11,080 gate counts. This demonstrates roughly 42% better than the aggregates of three algorithm implementations in the aspect of gate counts.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.82-96
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• 2019

A semi-submersible structure has been widely used for offshore drilling and production of oil and gas. The small water plane area makes the structure very sensitive to weight increase in terms of payload and stability. Therefore, it is necessary to lighten the substructure from the early design stage. This study aims at an optimization of hull structure based on a sophisticated yield and buckling strength in accordance with classification rules. An in-house strength assessment system is developed to automate the procedure such as a generation of buckling panels, a collection of required panel information, automatic buckling and yield check and so on. The developed system enables an automatic yield and buckling strength check of all panels composing the hull structure at each iteration of the optimization. Design variables are plate thickness and stiffener section profiles. In order to overcome the difficulty of large number of design variables and the computational burden of FE analysis, various methods are proposed. The steepest descent method is selected as the optimization algorithm for an efficient search. For a reduction of the number of design variables and a direct application to practical design, the stiffener section variable is determined by selecting one from a pre-defined standard library. Plate thickness is also discretized at 0.5t interval. The number of FE analysis is reduced by using equations to analytically estimating the stress changes in gradient calculation and line search steps. As an endeavor to robust optimization, the number of design variables to be simultaneously optimized is divided by grouping the scantling variables by the plane. A sequential optimization is performed group by group. As a verification example, a central column of a semi-submersible structure is optimized and compared with a conventional optimization of all design variables at once.