• Title/Summary/Keyword: proof-error

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Machine Learning Based Prediction of Bitcoin Mining Difficulty (기계학습 기반 비트코인 채굴 난이도 예측 연구)

  • Lee, Joon-won;Kwon, Taekyoung
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.29 no.1
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    • pp.225-234
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    • 2019
  • Bitcoin is a cryptocurrency with characteristics such as de-centralization and distributed ledger, and these features are maintained through a mining system called "proof of work". In the mining system, mining difficulty is adjusted to keep the block generation time constant. However, Bitcoin's current method to update mining difficulty does not reflect the future hash power, so the block generation time can not be kept constant and the error occurs between designed time and real time. This increases the inconsistency between block generation and real world and causes problems such as not meeting deadlines of transaction and exposing the vulnerability to coin-hopping attack. Previous studies to keep the block generation time constant still have the error. In this paper, we propose a machine-learning based method to reduce the error. By training with the previous hash power, we predict the future hash power and adjust the mining difficulty. Our experimental result shows that the error rate can be reduced by about 36% compared with the current method.

A Comparative Study on bank's responsibilities in the Electronic Payment System -comparison between Korea and U.S.A- (국제 전자결제시스템에서 금융기관의 책임 및 정책적 시사점 -한국과 미국의 전자금융제도 비교-)

  • Lee, Byeong-Ryul
    • International Commerce and Information Review
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    • v.12 no.1
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    • pp.35-54
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    • 2010
  • This article explored the bank's responsibilities in electronic payment system between Korea and U.S.A. In order to complete my research object, I used Article 4A of the U.C.C. and EFTA of 1978 and by Electronic Financial Transaction Act of Korea as a analytic instruments. I also adapted America's various regulations to regulate concerned parties(banks). The system of this article is going to display as fellows; First, I presented recent trend and legal stabilities of electronic payment in this article. Second, I focuses on the allocation of risk of loss caused by ambiguous term in payment orders that do not express the subjective intention of the senders. I also did analyze the solution procession of error occurring in course of send of payment order. Third, In any action which involves a customers's liability for an unauthorized electronic fund transfer, the burden of proof is upon the financial institution to show that the electronic fund transfer was authorized. Forth, Customers have to report the error and unauthorized electronic fund transfer after awaring of it. Then bank will be liable for such a unauthorized electronic fund transfer. But If customer's failure to report, the bank has exemptions. Lastly, In order to prevent or detect the unauthorized electronic fund transfer, bank will agree with custom to establish a commercially reasonable security procedure, while bank has duties to notify in order to decrease the loss resulted from unauthorized payment order in korea law.

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Estimation of Hurst Parameter in Longitudinal Data with Long Memory

  • Kim, Yoon Tae;Park, Hyun Suk
    • Communications for Statistical Applications and Methods
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    • v.22 no.3
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    • pp.295-304
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    • 2015
  • This paper considers the problem of estimation of the Hurst parameter H ${\in}$ (1/2, 1) from longitudinal data with the error term of a fractional Brownian motion with Hurst parameter H that gives the amount of the long memory of its increment. We provide a new estimator of Hurst parameter H using a two scale sampling method based on $A{\ddot{i}}t$-Sahalia and Jacod (2009). Asymptotic behaviors (consistent and central limit theorem) of the proposed estimator will be investigated. For the proof of a central limit theorem, we use recent results on necessary and sufficient conditions for multi-dimensional vectors of multiple stochastic integrals to converges in distribution to multivariate normal distribution studied by Nourdin et al. (2010), Nualart and Ortiz-Latorre (2008), and Peccati and Tudor (2005).

OPTIMAL ERROR ESTIMATE FOR SEMI-DISCRETE GAUGE-UZAWA METHOD FOR THE NAVIER-STOKES EQUATIONS

  • Pyo, Jae-Hong
    • Bulletin of the Korean Mathematical Society
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    • v.46 no.4
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    • pp.627-644
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    • 2009
  • The gauge-Uzawa method which has been constructed in [11] is a projection type method to solve the evolution Navier-Stokes equations. The method overcomes many shortcomings of projection methods and displays superior numerical performance [11, 12, 15, 16]. However, we have obtained only suboptimal accuracy via the energy estimate in [11]. In this paper, we study semi-discrete gauge-Uzawa method to prove optimal accuracy via energy estimate. The main key in this proof is to construct the intermediate equation which is formed to gauge-Uzawa algorithm. We will estimate velocity errors via comparing with the intermediate equation and then evaluate pressure errors via subtracting gauge-Uzawa algorithm from Navier-Stokes equations.

A Second-Order Iterative Learning Algorithm with Feedback Applicable to Nonlinear Systems (비선형 시스템에 적용가능한 피드백 사용형 2차 반복 학습제어 알고리즘)

  • 허경무;우광준
    • Journal of Institute of Control, Robotics and Systems
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    • v.4 no.5
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    • pp.608-615
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    • 1998
  • In this paper a second-order iterative learning control algorithm with feedback is proposed for the trajectory-tracking control of nonlinear dynamic systems with unidentified parameters. In contrast to other known methods, the proposed teaming control scheme utilize more than one past error history contained in the trajectories generated at prior iterations, and a feedback term is added in the learning control scheme for the enhancement of convergence speed and robustness to disturbances or system parameter variations. The convergence proof of the proposed algorithm is given in detail, and the sufficient condition for the convergence of the algorithm is provided. We also discuss the convergence performance of the algorithm when the initial condition at the beginning of each iteration differs from the previous value of the initial condition. The effectiveness of the proposed algorithm is shown by computer simulation result. It is shown that, by adding a feedback term in teaming control algorithm, convergence speed, robustness to disturbances and robustness to unmatched initial conditions can be improved.

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Medico-legal Consideration of Gastric Lavage in Acute Intoxicated Patients -In the Supreme Court 2005.1.28, 2003da14119 (급성 약물중독 환자에서 위세척의 의료법학적 고찰 -대법원 2005.1.28, 2003다1419 판결을 중심으로-)

  • Bae, Hyun-A
    • Journal of The Korean Society of Clinical Toxicology
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    • v.3 no.1
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    • pp.1-10
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    • 2005
  • Gastric lavage is now known to be ineffective, unnecessary or hazardous in some circumstances where it used to be performed as a routine. This article concerns the medico-legal aspect of forced gastric lavage. The Supreme Court 2005.1.28, 2003da14119 is the case where a patient, who ingested the organophosphate insecticide to attempt suicide and refused lavage. At first we discuss the effectiveness or hazards of lavage because a very high degree of proof -of negligence, not error of clinical judgment - would be required. Lavage, with or without the informed consent, performed negligently which result in harm could, of course, give rise to a claim in negligence. A doctor might also be held negligent in failing to perform an act which he/she had a duty to perform.

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Fast Parallel Algorithm For Optimal Stack Filter Design (최적 스택필터 설계를 위한 고속병렬기법)

  • Yoo, Ji-Sang
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.36S no.2
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    • pp.88-95
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    • 1999
  • Stack filters are a class of digital nonlinear filters with excellent properties for signal restoration. Unfortunately, present algorithms for designing stack filters with large window size are limited in applications by their computational overhead and serial nature. In this paper, new, highly-parallel algorithm is developed for determining a stack filter which minimizes the mean absolute error criterion. It retains the iterative nature of the present adaptive algorithm, but significantly reduces the number of required to converge to an optima filter. A proof is also give that the proposed algorithm converges to an optimal stack filter.

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CONVERGENCE ANALYSIS ON GIBOU-MIN METHOD FOR THE SCALAR FIELD IN HODGE-HELMHOLTZ DECOMPOSITION

  • Min, Chohong;Yoon, Gangjoon
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.18 no.4
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    • pp.305-316
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    • 2014
  • The Hodge-Helmholtz decomposition splits a vector field into the unique sum of a divergence-free vector field (solenoidal part) and a gradient field (irrotational part). In a bounded domain, a boundary condition needs to be supplied to the decomposition. The decomposition with the non-penetration boundary condition is equivalent to solving the Poisson equation with the Neumann boundary condition. The Gibou-Min method is an application of the Poisson solver by Purvis and Burkhalter to the decomposition. Using the $L^2$-orthogonality between the error vector and the consistency, the convergence for approximating the divergence-free vector field was recently proved to be $O(h^{1.5})$ with step size h. In this work, we analyze the convergence of the irrotattional in the decomposition. To the end, we introduce a discrete version of the Poincare inequality, which leads to a proof of the O(h) convergence for the scalar variable of the gradient field in a domain with general intersection property.

A Design of Verification Framework for Java Bytecode (자바 바이트코드의 검증을 위한 프레임워크 설계)

  • Kim, Je Min;Park, Joon Seok;Yoo, Weon Hee
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.7 no.2
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    • pp.29-37
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    • 2011
  • Java bytecode verification is a critical process to guarantee the safety of transmitted Java applet on the web or contemporary embedded devices. We propose a design of framework which enables to analyze and verify java bytecode. The designed framework translates from a java bytecode into the intermediate representation which can specify a properties of program without using an operand stack. Using the framework is able to produce automatically error specifications that could be occurred in a program and express specifications annotated in intermediate representation by a user. Furthermore we design a verification condition generator which converts from an intermediate representation to a verification condition, a verification engine which verifies verification conditions from verification condition generator, and a result reporter which displays results of verification.

Stable Input-Constrained Neural-Net Controller for Uncertain Nonlinear Systems

  • Jang-Hyun Park;Gwi-Tae Park
    • KIEE International Transaction on Systems and Control
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    • v.2D no.2
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    • pp.108-114
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    • 2002
  • This paper describes the design of a robust adaptive controller for a nonlinear dynamical system with unknown nonlinearities. These unknown nonlinearities are approximated by multilayered neural networks (MNNs) whose parameters are adjusted on-line, according to some adaptive laws far controlling the output of the nonlinear system, to track a given trajectory. The main contribution of this paper is a method for considering input constraint with a rigorous stability proof. The Lyapunov synthesis approach is used to develop a state-feedback adaptive control algorithm based on the adaptive MNN model. An overall control system guarantees that the tracking error converges at about zero and that all signals involved are uniformly bounded even in the presence of input saturation. Theoretical results are illustrated through a simulation example.

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