• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.512-514
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• 2003

본 논문은 신뢰할 수 없는 네트워크를 통해서 사용자를 인증하거나 키를 교환하는 것에 적합한 패스워드 기반 프로토콜을 제안한다. 기존의 패스워드 기반의 프로토콜들은 클라이언트와 서버 사이에 인증기관(CA)을 통하여 사용자를 인증하는 반면, 본 논문에서는 사용자와 서버가 독립적으로 키 교환 및 인증을 하는 패스워드 기반 프로토콜을 제안한다. 충분하지 않은 패스워드의 랜덤성과 짧은 길이로 인하여 패스워드를 사용해 인증 및 키 교환을 하는 것은 많은 주의를 요한다. 그러므로 Diffie-Hellman 키 교환 방식에 기반한 SRP 프로토콜과 ECDSA의 서명 기법을 적용하여 안전성이 높은 프로토콜을 제안한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.297-297
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• 2006

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.689-692
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• 2001

본 논문에서는 주어진 제약조건을 만족하며 저비용 고효율의 목적물 합성을 위하여 어느 부분을 하드웨어로 또는 소프트웨어로 구현할 것인지를 결정하는 분할 알고리즘을 제안한다. 논문[6]에서 제시한 시뮬레이티드 어닐링의 후보자 선택은 랜덤한 방식에 의해 노드의 이동이 이루어지기 때문에 중복된 후보자의 선택으로 인하여 시간이 오래 걸리는 단점이 있다. 이러한 단점을 극복하기 위해, 본 논문에서는 비용 함수를 구성하는 변수들 중에서 시스템 실행시간과 구현 비용에 영향을 미칠 수 있는 부분들을 고려해 후보자를 선택하도록 하여 최적해 탐색을 위한 분할 알고리즘의 실행 시간을 단축시켰다. 실험 결과는 대상 노드가 많아질수록 기존의 방법보다 빠른 시간에 최적의 해를 탐색한다.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.59-64
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• 2006

Harn al proposed a GKRS(Global Key Recovery System) that combines the functions of the key recovery authorities and the public key certification authorities(CA), Among other features, user dominance(i.e, a user is allowed to select his own public-private key pair and especially a public element for verifying the validity of the public-private key pair)is proposed by [1] for wide acceptance of GKRS. In this paper, we attack the RSA version of GKRS by showing that its user-dominance feature and the corresponding key verification scheme employed by the CA allow for fraud by users against CA. We propose more secure GKPS than original GKPS, The proposed system makes the probability of user fraud negligible small.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.5
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• pp.370-376
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• 2020

In this study, we consider a group-based random access method for group connection and delivery by grouping devices when H2H devices and large-scale M2M devices coexist in a cell in NB-IoT environment. H2H devices perform individual random access, but M2M devices are grouped according to a NPRACH transmission period, and a leader of each group performs random access. The preamble is allocated using the variable preamble allocation algorithm of the Disjoint Allocation(DA) method. The proposed preamble allocation algorithm is an algorithm that preferentially allocates preambles that maximizes throughput of H2H to H2H devices and allocates the rest to M2M devices. The access distribution of H2H and M2M devices was set as Poisson distribution and Beta distribution, respectively, and throughput, collision probability and resource utilization were analyzed. As the random access transmission slot is repeated, the proposed preamble allocation algorithm decreases the collision probability from 0.93 to 0.83 and 0.79 when the number M2M device groups are 150. In addition, it was found that the amount of increase decreased to 33.7[%], 44.9[%], and 48.6[%] of resource used.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.8
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• pp.22-33
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• 2009

Mobile Ad Hoc Networks (MANETs) are self-organized networks that do not rely in their operation on wired infrastructure. As in any networking technology, security is an essential element in MANET as well, for proliferation of this type of networks. But supporting secure communication in MANETs proved to be a significant challenge, mainly due to the fact that the set of nodes in the network can change frequently and rapidly and due to the lack of access to the wired infrastructure. In particular, the trust model and the authentication protocols, which were developed for wired and infrastructure-based networks, cannot be used in MANETs. In [1], we addressed the problem of efficient authentication of distributed mobile users in geographically large networks and proposed a new authentication scheme for this case of MANETs. The proposed scheme exploits randomized groups to efficiently share authentication information among nodes that together implement the function of a distributive Certification Authority(CA). In this paper, we analyze numerically the performance of authentication method using randomized groups and compare with the simulation result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.1
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• pp.17-30
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• 1985

The error rate performances of digital modulation systems in fluenced by impulsive noise have been investigated and discussed in the enviroment of electromagnetic interference(EMI). Using the derived equations for the probabilities of error of L-level ASK, M-ary PSK, MSK, QAM, and APK signals, the error rate performance of each system has been evaluated and compared each other. The results show that, in the case of gaussian noise enviornment, PSK system is superior to the other systems and the digital amplitude modulation systems are inferior on the contrary. In the environment of impulsive noise, the MSK at low interfere level shows the best error rate performance but in the high level interferer environment, the PSK shows the best error rate performance. Also it is known that the digital amplitude modulation systems are scarcely influenced by the variation of interfere level.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.487-492
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• 2022

Universities are looking for various methods to enhance educational competence level suitable for the rapidly changing social environment. This study suggests a method to promote academic and educational achievements by reducing drop-out rate from their majors through implementation of pre-survey of satisfaction that revised and complemented survey items. To supplement the CQI method implemented after a general satisfaction survey, a pre-survey of satisfaction was carried out. To consolidate students' competences, this study made prediction and analysis of data with more importance possible using the Random Forest of the machine learning technique that can be applied to AI Medici platform, whose design is underway. By pre-processing the pre-survey of satisfaction, the students information enrolled in classes were defined as an explanatory variable, and they were classified, and a model was created and learning was conducted. For the experimental environment, the algorithms and sklearn library related in Jupyter notebook 3.7.7, Python 3.7 were used together. This study carried out a comparative analysis of change in educational satisfaction survey, carried out after classes, and trends in the drop-out students by reflecting the results of the suggested method in the classes.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.364-371
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• 2004

This thesis is proposing novel RPWM(Random PWM) techniques that can locate PWM pulse to do random. RPWM techniques to propose locates SVPWM(Space Vector PWM) pulse by number of each random and principle to locate of pulse applies different random function and locate pulse. For propriety verification of proposed techniques, achieve an simulation and experiment that use MATLAB/SIMULINK about proposed RPWM techniques algorithm and IGBT inverter composition that use DSP(TMS320C31). Specially, analyze harmonic spectra of inverter output current when the induction motor speed is more than 10,000 rpm, confirm that RPWM's effect in high speed degree appears. Proposed RPWM techniques propriety prove from reduction effect of harmonic magnitude that corresponds to an integer times of switching frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.727-734
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• 2004

Collision Management Protocol (CMP) efficiently resolves collisions when data frames are transmitted in networks consisting of HomPNA 3.0 asynchronous MAC mode device with random access. Unlike Distributed Fair Priority Queueing (DFPQ) algorithm in HomePNA 2.0 or Binary Exponential Backoff (BEB) algorithm in IEEE 802.11, order of retransmission is decided according to Collision Signaling Sequence (CSS) values allocated to each device. Thus, CMP can minimize the number of mean collisions because order of retransmission is decided in a deterministic way. In this paper. we evaluate the saturation performance of CMP in HomePNA 3.0 using an analytic method.