• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.528-533
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• 2015

In the construction of USN environment, the implementation of a safe sensor network using wireless communications can be said to be the most important factor in the entire system. Although USN communication uses wireless communications to enhance accessability and non-contact capability, this results in the security vulnerability, thus endangering the system. In this regard, we propose a security protocol that can be effectively applied to USN, a multi-sensor network. The proposed protocol is a method using an individual chaotic system, and it is a security protocol to synchronize the main chaotic system mounted on each sensor and prepared key values into the initial values, and to communicate with the use of the synchronized values as symmetric keys. The communication protocol proposed in this paper is expected to yield good results as a new method to resolve security problems of USN and program capacity limitations of sensor nodes if subsequent studies continue to be carried out.

• Journal of IKEEE
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• v.21 no.1
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• pp.39-45
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• 2017

Image compression is now essential for applications such as transmission and storage in data bases. For video and digital image applications the use of long tap filters, while not providing any significant coding gain, may increase the hardware complexity. We use a wavelet transform in order to obtain a set of bi-orthogonal sub-classes of images; First, the design of short kernel symmetric analysis is presented in 1-dimensional case. Second, the original image is decomposed at different scales using a subband filter banks. Third, this paper is presented a technique for obtaining 2-dimensional bi-orthogonal filters using McClellan transform. It is shown that suggested wavelet bases is well used on wavelet transform for image compression. From performance comparison of bi-orthogonal filter, we actually use filters close to ortho-normal filters on application of wavelet bases to image analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.653-663
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• 2002

The signature-then-encryption based on RSA scheme provides forward secrecy, but requires 4 modulo exponentiation operations in total, and the signcryption scheme proposed by Zheng simultaneously fulfills both the functions of digital signature and symmetric key encryption in a logically single step, and with a computational cost significantly smaller than that required by the current standard signature-then-encryption, but it can not provide forward secrecy. In this paper, we propose an enhanced signcryption scheme which can provide forward secrecy with lower computational cost and lower communication overhead comparing with those of the signature-then-encryption based on RSA, and with a similar communication overhead of Zheng's scheme. The proposed scheme can be also easily modified to the direct signature verification scheme by the recipient without using the recipient's private key. Additionally, we suggest a new design protocol with server-supported signatures which solves the CRLs(Certificate Revocation Lists) burden and provides non-repudiation of origin. This protocol with server-supported signatures also can be applied to the original signcryption scheme proposed by Zheng in order to improve security.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.843-850
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• 2006

This is devoted to first, to propose a hash chain algorithm that generates more secure key than conventional encryption method. Secondly, we proposes encryption method that is more secure than conventional system using a encryption method that encrypts each block with each key generated by a hash chain algorithm. Thirdly, After identifying the user via wired and wireless network using a user authentication method. We propose a divided session key method so that Although a client key is disclosed, Attackers cannot catch a complete key and method to safely transfer the key using a divided key method. We make an experiment using various size of digital contents files for performance analysis after performing the design and implementation of system. Proposed system can distribute key securely than conventional system and encrypt data to prevent attacker from decrypting complete data although key may be disclosed. The encryption and decryption time that client system takes to replay video data fie is analogous to the conventional method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.57-62
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• 2009

In this paper, we proposed the metal tag antenna of PIFA structure with an isotropic radiation pattern when tag attached the metal material. The antenna consist of antenna body, horizontal patch and ground, and inserted a substrate with high dielectric constant between the antenna body and ground in order to miniaturize the antenna size. The antenna body with symmetric structure is designed to produce an oppositely directed currents. The simulation shows the impedance bandwidth has 20 MHz (900 ~ 920 MHz) and the maximum radiation gain satisfy the -10 dBi and -15 dBi when the tag is in air and attach the metal material. Also, the proposed antenna operates with an isotropic radiation pattern due to satisfy the gain deviation lower than 6 dB, respectively.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.1-8
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• 2008

The security of wireless sensor networks is a challenging research area where the resources constraints are a bottleneck for any successful security design. Due to their computational feasibility, symmetric key algorithms that require key pre-distribution are more desirable for use in these networks. In the pre-distribution scheme, keys or keying materials are assigned to each node prior deployment to guarantee a secure communication within the entire network. Though several works are introduced on this issue, yet the connectivity and resiliency are imperfectly handled. In this paper, we revisit the grid based key pre-distribution scheme aiming to improve the connectivity, introduce a higher resiliency level, simplify the logic of key establishment and maintain same level of used of resources usage. The core of our modification relies on introducing the novel plat-based polynomial assignment and key establishment mechanism. To demonstrate the advantageous properties of our scheme over the revisited one, details of consumed resources, resulting connectivity, security and comparisons with relevant works are introduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.21-26
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• 2016

This study evaluates the magnitudes and distributions of contact tangential forces with the swaging depth of punch acting at the contact surfaces between a rotor core slot and a Cu bar during a sequential rotor core swaging process. The effects of the core slot shape on the magnitudes and distributions of the total contact forces were investigated to improve the productivity of the rotor core swaging process. Parametric elastic-plastic numerical analyses were performed using simplified two-dimensional cyclic symmetric plane strain models to evaluate the contact force distributions at the contact surfaces. The numerical analysis results show that the total contact tangential forces increased by about 55% with the adjacent Cu bar swaging process. The length of the core slot is a dominant factor in the core slot design as result of the increased total contact tangential forces during the swaging process of the rotor core.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.9
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• pp.465-474
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• 2005

For high density SoC design, on-chip communication based on bus interconnection encounters bandwidth limitation while an NoC(Network-on-Chip) approach suffers from unacceptable complexity in its Implementation. This paper introduces a new on-chip communication protocol, SNP (SoC Network Protocol) to overcome these problems. In SNP, conventional on-chip bus signals are categorized into three groups, control, address, and data and only one set of wires is used to transmit all three groups of signals, resulting in the dramatic decrease of the number of wires. SNP efficiently supports master-master communication as well as master-slave communication with symmetric channels. A sequencing rule of signal groups is defined as a part of SNP specification and a phase-restoration feature is proposed to avoid redundant signals transmitted repeatedly over back-to-back transactions. Simulation results show that SNP provides about the same bandwidth with only $54\%$ of wires when compared with AMBA AHB.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.299-304
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• 2008

Starting characteristics of the axi-symmetric second throat exhaust diffuser (STED) with zero-secondary flows are numerically investigated. Renolds-Average Navier-Stokes equations with a standard ${\kappa}-{\varepsilon}$ turbulence model incorporated with enhanced wall treatment are solved to simulate the diffusing evolutions of the nozzle plume. Minimum (optimum) starting pressure difference of 20$\sim$25% between 1-D theory and the measured data validated from previous results[5] is also applied to predict the range of an effective diffuser expansion ratio (Ad/At) in this system.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.697-702
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• 2010

A WIG(Wing-In-Ground effect) craft flies close to the water surface by utilizing a cushion of relatively high pressurized air between its wing and water surface. This implies that when one designs such craft it is important to have lightweight structures with adequate strength to resist external loads with some margins. To investigate this requirement, this paper deals with the structural analysis of the bottom plate of small WIG craft having a design landing weight of 1.2-ton. As building materials for the WIG craft, pre-preg carbon/epoxy composites are considered. The strength information of the bottom plate is obtained using the first-ply-failure analysis in conjunction with a mid-plane symmetric laminated plate theory. As a result, the first-ply-failure location, load and deflection of the bottom plate are obtained. The calculated strength information is compared with the water reaction load for the bottom plate of seaplanes considered when they land on the water surface -the same fluid-structure interaction mechanism as that of WIG craft. In the calculation of seaplane water reaction load information, the rules shown in FAR(Federal Aviation Regulations) Part 25 are used. Through the comparison, the structural integrity of the bottom plate for the WIG craft is checked.