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The tension field of the energy functional on Riemannian submersion
최부용 충청수학회 2011 충청수학회지 Vol.24 No.2
In this paper, we will study the tension field of the function related to a Riemannain submersion : N → M with totally geodesic fibres. In case that the Riemannain submersion π : N → M particularly has a smooth map f:M → N which happens to be a section, we will show that tension field τ(f) of the energy functional can be decomposed into the horizontal and vertical parts.
Analysis of the Vlasov-Poisson equation by using a viscosity term
최부용,강순부,이문식 충청수학회 2013 충청수학회지 Vol.26 No.3
The well-known Vlasov-Poisson equation describes plasma physics as nonlinear first-order partial differential equations. Because of the nonlinear condition from the self consistency of the Vlasov-Poisson equation, many problems occur: the existence, the numerical solution, the convergence of the numerical solution, and so on. To solve the problems, a viscosity term (a second-order partial differential equation) is added. In a viscosity term, the Vlasov-Poisson equation changes into a parabolic equation like the Fokker-Planck equation. Therefore, the Schauder fixed point theorem and the classical results on parabolic equations can be used for analyzing the Vlasov-Poisson equation. The sequence and the convergence results are obtained from linearizing the Vlasove-Poisson equation by using a fixed point theorem and Gronwall's inequality. In numerical experiments, an implicit first-order scheme is used. The numerical results are tested using the changed viscosity terms.
RSA 알고리즘에 기반한 효율적인 공모자 추적 암호 시스템
최부용,이문식 한국국방경영분석학회 2011 한국국방경영분석학회지 Vol.37 No.3
Traitor Tracing schemes deter traitors from sharing their private keys by tracing at least one of the subscribers who were implicated in the construction of a pirate decoder. In this paper, we propose an efficient traitor tracing scheme based on the RSA cryptosystem using the ElGamal encryption system. The proposing system which applies RSA cryptosystem is k-collusion resilient scheme. It revoke traitor's key or unauthorized subscribers from system network without key updating, and can trace the colluders using black box tracing method. The security of this paper is based on the RSA's. The communication cost of the center is O(k+l), the storage of private key is O(k+2logN). and it requires modulo multiplication, one exponentiation for calculation, if we choose the small parameter , it will be effective, since there is no difference from RSA cryptosystem. Furthermore, proposing scheme which can be applied for the broadcast encryption system of the futuer defense millitary has merits for managing the secret document system and will contribute to administering an organization of the military in the information security.
최재동,최부용 외 1인 空軍士官學校 2001 論文集 Vol.48 No.-
이 논문에서는 로버트슨 와커의 시공간에서의 곡률을 연구한 논문으로 곡률 중에서 시간축과 공간축의 벡터로 이뤄지는 단면곡률의 일반적인 형태를 구하였으며 우주의 한 모델인 로버트슨-와커 공간에서 빅뱅에 대응되는 빅클런치 점을 갖지 않는 조건을 구하였다.
G-induced Loss of Consciousness(G-LOC) 예측을 위한 신체 부위별 Electromyogram(EMG) 신호 분석
김성호,김동수,조태환,이용균,최부용,Kim, Sungho,Kim, Dongsoo,Cho, Taehwan,Lee, Yongkyun,Choi, Booyong 한국군사과학기술학회 2017 한국군사과학기술학회지 Vol.20 No.1
G-induced Loss of Consciousness(G-LOC) can be predicted by measuring Electromyogram(EMG) signals. Existing studies have mainly focused on specific body parts and lacked of consideration with quantitative EMG indices. The purpose of this study is to analyze the indices of EMG signals by human body parts for monitoring G-LOC condition. The data of seven EMG features such as Root Mean Square(RMS), Integrated Absolute Value(IAV), and Mean Absolute Value(MAV) for reflecting muscle contraction and Slope Sign Changes(SSC), Waveform Length (WL), Zero Crossing(ZC), and Median Frequency(MF) for representing muscle contraction and fatigue was retrieved from high G-training on a human centrifuge simulator. A total of 19 trainees out of 47 trainees of the Korean Air Force fell into G-LOC condition during the training in attaching EMG sensor to three body parts(neck, abdomen, calf). IAV, MAV, WL, and ZC under condition after G-LOC were decreased by 17 %, 17 %, 18 %, and 4 % comparing to those under condition before G-LOC respectively. Also, RMS, IAV, MAV, and WL in neck part under condition after G-LOC were higher than those under condition before G-LOC; while, those in abdomen and calf part lower. This study suggest that measurement of IAV and WL by attaching EMG sensor to calf part may be optimal for predicting G-LOC.