• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.4
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• pp.376-384
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• 2009

In this article, we demonstrate that the asymmetric key-based architecture for securing wireless sensor networks recently introduced by Haque et al. is insecure under impersonation attack, since it does not provide authentication semantics. In addition, we show that, for the scheme to work correctly, the resulting key distribution construction should be symmetric and group-wise.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.259-262
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• 2005

This paper addresses the problem of protecting security policies in security mechanisms, such as the detection policy of an Intrusion Detection System. Unauthorized disclosure of such information might reveal the fundamental principles and methods for the protection of the whole network. In order to avoid this risk, we suggest two schemes for protecting security policies in Snort using the symmetric cryptosystem, Triple-DES.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.1918-1925
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• 1989

A method for computing the capacitance and inductance matrix for 2-D multiconductor transmission lines with arbitrary cross section in dielectric medium is presented. The integral equation is obtained by using a free space Green function in conjunction with free and bound charges existing on boundary surfaces. The numerical analysis is based on the moment method using point matching and Galerkin method. And kthe scheme to reduce memory and computation time is presented for symmetric structure.

• East Asian mathematical journal
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• v.37 no.1
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• pp.1-7
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• 2021

In modern block ciphers, S-box plays a very important role in the secrets of symmetric encryption algorithms. Many popular block ciphers have adopted various S-Boxes to design better S-Boxes. Among the researches, Jin et al. proposed a simple scheme to create a new S-box from Rijndael S-box. Only one of the new S-boxes for 29 is a bijection with a better algebraic representation than the original. Therefore, they asked a few questions. In this paper, we answer the following question : When the resulting S-box is bijection?

• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.3
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• pp.1-8
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• 1987

In this paper, the localized finite element method(LFEM) is applied to 3-dimensional ship motion problems in water of infinite depth. The LFEM used here is based on the functional constructed by Bai & Yeung(1974). To test the present numerical scheme, a few vertical axisymmetric bodies are treated by general 3-dimensional formulation. The computed results of hydrodynamic coefficients for a few vertical spheroids and vertical circular cylinders show good agreement with results obtained by others. The advantages of the present numerical method compared with the method of integral equation are as follows; (i) The cumbersome existence of irregular frequencies in the method of conventional integral equation is removed. (ii) The final matrix is banded and symmetric and the computation of the matrix elements is comparatively easier, whereas the size of the matrix in the present scheme is much larger. (iii) In the future research, it is possible to accommodate with the nonlinear exact free surface boundary condition in the localized finite element subdomain, whereas the linear solution is assumed in the truncated(far field) subdomain.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.1-11
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• 1999

The three-dimensional laminar mixed convection flow between the conductive printed circuit boards. on which the heat generating rectangular blocks are uniformly distributed, has been examined in the present study. The flow and heat-transfer characteristics are assumed to be pseudo periodic in the streamwise direction and symmetric in the cross-stream direction. Using an algorithm of SIMPLER, the continuity equation. the Navier-Stokes equations and the energy equation are solved numerically in the three-dimensional domain Inside the channel. The convective derivative terms are discretized by the QUICK scheme to accurately capture the flow field. The flow and the heat transfer characteristics are thoroughly examined for various Re and Gr.

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.469-481
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• 2004

In this paper, we investigate the mean queue length and the mean packet delay of a dynamic bandwidth allocation(DBA) scheme in an Ethernet passive optical network(EPON). We focus on the interleaved polling system with a gated service discipline. We assume that input packets arrive at an optical network unit(ONU) according to Poisson process. We use a continuous time queueing model in order to find the queue length distribution of the gated interleaved polling system with the first stage input queue and the second stage transmission queue. We give some numerical results to investigate the mean queue lengths and mean packet delays for the symmetric polling system with statistically identical stations.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.11
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• pp.133-140
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• 1982

In recent years, a number of thyristor-controlled shunt compensators have been used in industrial and utility systems for phase balancing, power-factor correction and flicker reduction. This paper describes a simple and basic control scheme and circuits for shunt compensator with a fixed capacitor and thyristor-controlled reactor. Feedforward-control scheme is applied, and compensating currents are computed from the symmetrical components of the disturbed system. A 8 bit microprocessor is used for the computation of the compensating currents as well as for the measurements of the symmetric components. A 3-phase 1 KVA compensator is developed and a good reduction of the unbalance factor of the power source is achieved using it.

• Current Optics and Photonics
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• v.5 no.2
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• pp.155-163
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• 2021

We propose a novel optical encryption scheme for cipher-feedback-block (CFB) mode, capable of encrypting two-dimensional (2D) page data with the use of two-step phase-shifting digital interferometry utilizing orthogonal polarization, in which the CFB algorithm is modified into an optical method to enhance security. The encryption is performed in the Fourier domain to record interferograms on charge-coupled devices (CCD)s with 256 quantized gray levels. A page of plaintext is encrypted into digital interferograms of ciphertexts, which are transmitted over a digital information network and then can be decrypted by digital computation according to the given CFB algorithm. The encryption key used in the decryption procedure and the plaintext are reconstructed by dual phase-shifting interferometry, providing high security in the cryptosystem. Also, each plaintext is sequentially encrypted using different encryption keys. The random-phase mask attached to the plaintext provides resistance against possible attacks. The feasibility and reliability of the proposed CFB method are verified and analyzed with numerical simulations.

• ETRI Journal
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• v.41 no.4
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• pp.465-472
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• 2019

The major challenge in wireless body area networks (WBAN) is setting up a protected communication between data consumers and a body area network controller while meeting the security and privacy requirements. This paper proposes efficient and secure data communication in WBANs using a Twofish symmetric algorithm and ciphertext-policy attribute-based encryption with constant size ciphertext; in addition, the proposed scheme incorporates policy updating to update access policies. To the best of the author's knowledge, policy updating in WBAN has not been studied in earlier works. The proposed scheme is evaluated in terms of message size, energy consumption, and computation cost, and the results are compared with those of existing schemes. The result shows that the proposed method can achieve higher efficiency than conventional methods.