• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 춘계학술발표대회
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• pp.760-762
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• 2011

Data centers are usually under provisioned. This is not a problem in corporate data networks, but it can be a problem in cloud data networks. If an application is being served by that cloud infrastructure, the application owner must know the infrastructure limitations and should take some special measures to ensure QoS/availability of that application and to prevent against possible threats. In this paper we have discussed a new form of DoS that could take place in a cloud data network using the vulnerability caused by under provisioned network. We have also proposed a solution for this DoS attack, by which not only this attack will be detected, but can also be avoided in a very short time.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3515-3524
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• 2023

A reinforcement learning framework is proposed for the control problem of outlet steam pressure of the once-through steam generator(OTSG) in this paper. The double-layer controller using Proximal Policy Optimization(PPO) algorithm is applied in the control structure of the OTSG. The PPO algorithm can train the neural networks continuously according to the process of interaction with the environment and then the trained controller can realize better control for the OTSG. Meanwhile, reinforcement learning has the characteristic of difficult application in real-world objects, this paper proposes an innovative pretraining method to solve this problem. The difficulty in the application of reinforcement learning lies in training. The optimal strategy of each step is summed up through trial and error, and the training cost is very high. In this paper, the LSTM model is adopted as the training environment for pretraining, which saves training time and improves efficiency. The experimental results show that this method can realize the self-adjustment of control parameters under various working conditions, and the control effect has the advantages of small overshoot, fast stabilization speed, and strong adaptive ability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.64.1-64
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• 2002

$\textbullet$ Introduction $\textbullet$ CRA method for transient response control $\textbullet$ Benchmark problem and specifications $\textbullet$ Controller design using CRA method $\textbullet$ Concluding Remark

• 호남수학학술지
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• 제26권4호
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• pp.589-608
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• 2004

We investigate the multiplicity of the periodic solutions of the nonlinear wave equation with jumping nonlinearity. By category theory we prove that the jumping problem has at least 2k+1 solutions for the positive source term.

• 한국공간구조학회논문집
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• 제3권4호
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• pp.59-67
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• 2003

Genetic algorithm is one of the best ways to solve a discrete variable optimization problem. Genetic algorithm tends to thrive in an environment in which the search space is uneven and has many hills and valleys. In this study, genetic algorithm is used for solving the design problem of gable structure. The design problem of frame structure has some special features(complicate design space, many nonlinear constrants, integer design variables, termination conditions, special information for frame members, etc.), and these features must be considered in the formulation of optimization problem and the application of genetic algorithm. So, 'FRAME operator', a new genetic operator for solving the frame optimization problem effectively, is developed and applied to the design problem of gable structure. This example shows that the new opreator has the possibility to be an effective frame design operator and genetic algorithm is suitable for the frame optimization problem.

• Structural Engineering and Mechanics
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• 제2권3호
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• pp.295-309
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• 1994

The present paper concerns the mathematical study and the numerical treatment of the problem of semirigid connections in bolted steel column base plates by taking into account the possibility of appearance of separation phenomena on the contact surface under certain loading conditions. In order to obtain a convenient discrete form to simulate the structural behaviour of a steel column base plate, the continuous contact problem is first formulated as a variational inequality problem or, equivalently, as a quadratic programming problem. By applying an appropriate finite element scheme, the discrete problem is formulated as a quadratic optimization problem which expresses, from the standpoint of Mechanics, the principle of minimum potential energy of the semirigid connection at the state of equilibrium. For the numerical treatment of this problem, two effective and easy-to-use solution strategies based on quadratic optimization algorithms are proposed. This technique is illustrated by means of a numerical application.

• 한국초등과학교육학회지:초등과학교육
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• 제33권1호
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• pp.105-114
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• 2014

The purpose of this study was to develop a teaching strategy focused on problem solving process and explore its effects on science creative problem solving ability, science process skills, science academic achievements and scientific attitudes of students after applying it. Teaching strategy focused on problem solving process employed brainstorming and PMI thinking strategies. The participants were the third grade students of both an experimental class(26 students) and a comparative class(25 students) at the S elementary school located in Goyang-City, Kyonggi Province. The developed strategy was applied to the experimental class for 9 periods of 'Separation of mixture' unit. The results of the tests on the science creative problem solving ability, the science process skills, scientific achievement and scientific attitude were statistically higher in the experimental class.

• 한국경영과학회지
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• 제19권1호
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• pp.53-67
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• 1994

Over the last decades, interest in the application of decision support systems (DSS) in organizations has increased rapidly. Despite the growing number of investigations exmaining decision support system, relatively few empirical studies have evaluated the effects of DSS on problem-solving processes. This study examined, using a computer simulation technique, the effects of recursion in problem-solving processes on the problem-solving time. Results indicate that the recursions at the early stage of problem-solving processes scarcely influenced the problem-solving time, which is contrasted with the case of the recursions at the final stage.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.17-27
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• 2021

Non-abelian group based cryptosystems are a latest research inspiration, since they offer better security due to their non-abelian properties. In this paper, we propose a novel approach to non-abelian group based public-key cryptographic protocols using semidirect products of finite groups. An intractable problem of determining automorphisms and generating elements of a group is introduced as the underlying mathematical problem for the suggested protocols. Then, we show that the difficult problem of determining paths and cycles of Cayley graphs including Hamiltonian paths and cycles could be reduced to this intractable problem. The applicability of Hamiltonian paths, and in fact any random path in Cayley graphs in the above cryptographic schemes and an application of the same concept to two previous cryptographic protocols based on a Generalized Discrete Logarithm Problem is discussed. Moreover, an alternative method of improving the security is also presented.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제21권2호
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• pp.177-197
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• 2007

본 연구에서는 문제해결력, 수학화 및 실생활 문제에 대한 이론적 배경을 살펴보고, 중학교 수학교사와 일반계 고등학교 1학년 학생들을 대상으로 중학교 수학의 도형 영역에 속하는 각 단계별 주요 내용과 관련하여 실생활 문제에 대한 인식을 조사하여 문제점을 알아본다. 그 결과에 따라 8단계와 9단계 수학의 도형 영역을 중심으로 교과서에 제시되어 있는 실생활 문제를 분석하여 문제점을 제시하고, 문제해결력 향상을 위한 실생활 문제의 개발과 함께 그 적용에 대해 제안한다.