• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.07a
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• pp.299-302
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• 2003

본 논문에서는 패스워드 검증자(verifier) 기반의 인증 및 키 교환 프로토콜을 제안한다. 제안한 프로토콜은 패스워드 기반 프로토콜들의 가장 큰 문제점인 패스워드 추측공격과 중간 침입자 공격, 그리고 Denning-Sacco 공격에 안전하며, 완전한 전방향 보안성을 제공할 수 있다. 그리고 패스워드 검증자를 기반으로 하기 때문에 서버의 패스워드 파일의 노출에도 안전하다. 제안된 프로토콜의 안전성은 이산대수 문제와 Diffie-Hellman 문제의 어려움, 그리고 해쉬 함수의 암호학적 강도에 기반을 두고 있다. 또한 제안한 프로토콜은 구조가 간단하고 병렬 처리가 가능하기 때문에 안전하다고 알려진 기존의 프로토콜들과 비교하여 효율적이다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.07a
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• pp.89-92
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• 2003

Diffie-Hellman(DH) 키공유 기법［1］이 제안된 후 많은 종류의 키공유 기법들이 연구되었으며, 특히 특정한 그룹 내의 구성원들이 안전한 통신을 할 수 있게 하기 위한 그룹 기반의 키공유 기법들에 대한 많은 방식들이 제안되었다. 이러한 방식들은 PKI 기반 구조 등을 사용하는 여러 응용들에서 쉽게 사용될 수 있지만, Ad-hoc 통신망이라는 특정한 기반구조를 사용할 수 없는 환경에서는 적용하기가 쉽지 않다. ［2］에서는 Ad-hoc 환경에서의 그룹(conference) 기반의 키공유 기법을 제안하였지만, (n＋2)-라운드의 통신량이 요구되며, 그룹 구성원들의 위치정보를 알고 있어야 한다. 본 논문에서는 ad-hoc 환경에서의 효율적이며, 그룹 구성원들의 위치정보를 알 필요 없는 2-라운드 키공유 기법을 제안한다.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.4
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• pp.28-34
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• 2010

W e performed a geometrical nonlinear dynamic analysis of laminated skew plates made of advanced composite materials (ACM ) based on the first-order shear deformation plate theory (FSDT). The Newmark method and Newton-Raphson iteration are used for the nonlinear dynamic solution. The effects of skew angles and layup sequences on the nonlinear dynamic response for various parameters are studied using a nonlinear dynamic finite element program developed for this study. The several numerical results were in good agreement with those reported by other investigators for square composite and skew plates, and the new results reported in this paper show the significant interactions between the skew angle and layup sequence in the skew laminate. Key observation points are discussed and a brief design guideline is given.

• Journal of the Korean Society for Advanced Composite Structures
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• v.4 no.1
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• pp.9-14
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• 2013

The dynamic analysis of poles made of advanced composite materials is carried out for different length-thickness ratios and layup sequences. The numerical results using ABAQUS obtained for plates and shells are in good agreement with those reported by other investigators. The new results for laminated composite pole structures in this study mainly show the effect of the interactions between the radius-length ratio and other various parameters. The effect of fiber angles of long composite poles also investigated. Key observation points are discussed and a brief design guideline is given.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.202-202
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• 2011

Diagnostics of plasma density is a key factor for monitoring plasma processing. Various probes are invented to measure plasma density and cut-off probe is a one of the most promising diagnostics tool for measuring plasma density. However, at the low density or high pressure the cut-off probe cannot clearly resolve the cut-off peak. Several reasons make this problem: Cut-off likes peaks caused by cavity resonances and weaken transmission spectrum signal at high pressure. Recently, You et al., have researched mechanism of cut-off probe and we improve the cut-off reliability and sensitivity base on that research. Modified cut-off antenna is adapted and bias cut-off probe method is tried. These experiment results have good agreement with the previous study and show good measurement characteristics.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.669-671
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• 1998

Engine immobilizer is the automobile security system which disables the engine if the secrete code in the transponder embedded in the key knob is not in agreement with the code in ECU of the car. There are many types of immobilizer systems, however, the encryption transponder type system is the most secure system due to the code verification method using an encryption method. As an example of the industry-university cooperation, the software development in the system is introduced in this paper.

• Earthquakes and Structures
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• v.9 no.6
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• pp.1313-1336
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• 2015

The self-centering prestressed concrete (SCPC) bridge pier with external dissipators is a novel structure, aiming at reducing residual deformation and facilitating the post-earthquake repair. This paper presents the configuration and mechanical behaviors of the pier. A theoretical model for the lateral force-displacement relationship under cyclic loading is developed. The proposed model comprises an iterative procedure which describes the deformation of dissipators under different conditions. Equations of pier stiffness after gap opening, as well as the equivalent viscous damping ratio, etc., are derived based on the proposed model. Existing cyclic load test results were used to validate the proposed model, and good agreement is observed between the analytical and test results.

• Journal of Biomedical Engineering Research
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• v.34 no.1
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• pp.40-45
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• 2013

The conventional simulators used the expensive commercial artificial heart with a limited performance, and focused on replicating the heart function. The arterial pressure is the key factor of the cardiovascular disease. The purpose of this study is to develop a simulator focused on the pressure wave. The simulator is composed of a step motor, slider-crank mechanism, piston-cylinder, two check valves, a elastic tube, and two reservoirs. With the changes of design parameters, the functions of the simulator were evaluated. The simulator shows the good agreement of the characteristics of the cardiovascular system.

• International Journal of Contents
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• v.11 no.3
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• pp.63-68
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• 2015

A novel unit cell for a high pass filter was designed based on a composite right/left-handed structure that uses a folded coplanar waveguide. The equivalent circuit model for the unit cell was extracted from the geometry of the unit cell, and the effect of each main parameter of the unit cell was analyzed. The equations to calculate the immittance values of the equivalent circuit elements were formulated, and moreover, the dispersion characteristics and energy the distributions of the electromagnetic fields were simulated to determine the characteristics of the composite right/left-handed structure. Finally, the high pass filters were implemented as a series of the proposed unit cells. We show that the experimental results were in good agreement with those obtained from the simulation. Thus, the high pass filter was found to achieve a baseband insertion loss of 3 dB and a stopband attenuation of 70 dB.

• International Journal of Contents
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• v.11 no.3
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• pp.34-38
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• 2015

A band stop filter is proposed with cascading unit cells that are based on a dual composite right/left-handed (D-CRLH) conductorbacked coplanar waveguide. The parameters of the unit cell have been analyzed to confirm the behavior of each component for the equivalent circuit of the cell. We simulated the dispersion characteristics and energy distribution and have determined that the unit cell has a D-CRLH property. The band stop filter was implemented by symmetrically cascading two of the proposed unit cells. The experimental results for the band stop filter revealed a band rejection performance of 32 dB and a return loss of 0.35 dB in the stopband frequency range from 869MHz to 954MHz. Finally, we show that there is a good agreement in the experimental results and those obtained through the simulations.