• 한국지반공학회논문집
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• 제21권2호
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• pp.145-150
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• 2005

사면 붕괴를 예측하기 위해서 적당한 수학적 모델을 선택하는 것은 매우 유용하다. 시간열로 실시간 계측된 자료를 통하여 합리적인 사면붕괴 예측용 수학모델을 선정할수 있다. 3차 방정식을 이용한2가지 형태의 이론적 모델이 이 연구에서 사용되었다(Polynomial 및 Growth형). 사면의 변위각 및 침하를 계측할 수 있는 계측기가 느릅재 및 북실 현장에 적용되어 모델의 적용가능성을 점검하였다. 그 결과 계측 자료와 두 가지 수학모델과 아주 높은 일치성을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권9호
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• pp.4197-4219
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• 2017

Cloud computing is a new service to provide dynamic, scalable virtual resource services via the Internet. Cloud market is available to multiple cloud computing resource providers and users communicate with each other and participate in market transactions. However, since cloud computing is facing with more and more security issues, how to complete the allocation process effectively and securely become a problem urgently to be solved. In this paper, we firstly analyze the cloud resource allocation problem and propose a mathematic model based on combinatorial double auction. Secondly, we introduce a trust evaluation mechanism into our model and combine genetic algorithm with simulated annealing algorithm to increase the efficiency and security of cloud service. Finally, by doing the overall simulation, we prove that our model is highly effective in the allocation of cloud resources.

• 한국지능시스템학회논문지
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• 제14권4호
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• pp.481-486
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• 2004

이족 로봇은 기존의 바퀴로 움직이는 로봇에 비해 더 큰 이동성을 가지고 있다. 하지만 현실적으로는 쉽게 넘어지는 경향이 있어서, 보행 시 동적인 안정성을 확보해야 할 필요성이 있다. 이를 위해서는 다양한 지면 조건에 대해 로봇 발의 움직임과 몸체의 움직임을 일치시키고, 기구학적 해석이나 동역학적 해석을 통하여 안정성을 확보해야 한다. 하지만 그 수학적 모델이 너무 난해하다는 단점이 있다. 본 논문에서는, 이족 로봇의 동적 보행에 있어서 안정성을 확보하기 위해 퍼지 모델을 설계하고, 시뮬레이션을 실현함으로써 본 논문에서 제안된 보행 알고리즘이 실현 가능한 것임을 확인한다.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.169-175
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• 2014

This paper presents an improved direct power control (DPC) strategy for grid-connected voltage source inverter (VSI) under unbalanced and harmonic grid voltage conditions. Based on the mathematic model of VSI with the negative sequence, 5th and 7th harmonic voltage components consideration, a PI controller is used in the proposed DPC strategy to achieve the average output power regulation. Furthermore, vector PI controller with the resonant frequency tuned at the two times and six times grid fundamental frequency is adopted to regulate both negative and harmonic components, and then two alternative targets of the balanced/sinusoidal current and smooth active/reactive output power can be achieved. Finally, simulation results based on MATLAB validate the availability of the proposed DPC strategy.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
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• pp.448-451
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• 2000

Fuzzy control has been researched for application of industrial processes which have no accurate mathematical model and could not controlled by conventional methods because of a lack of quantitative input-output data. Intelligent control approach based on fuzzy logic could directly reflex human thinking and natural language to controller comparing with conventional methods. In this paper, the tested system is constructed for sending a ball to the goal position using wind from two DC motors in the path. This system contains non-linearity and uncertainty because of the characteristic of aerodynamics inside the path. The system used in this experiment could be hardly modeled by mathematic methods and could not be easily controlled by linear control manners. The controller, in this paper could control the system containing non-linearity and uncertainty because it is designed based on the input-output data and experimental knowledge obtained by trials.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.164-166
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• 2006

Wien Automatic System Planning Package (WASP) which is used to draw out generation expansion planning applies Dynamic Programming in Korea power system panning. While this package has an advantage that computes annual capacity, it has a disadvantage that can't consider environmental constraints. With the effectuation of the Kyoto Protocol in February, 2005, it is expected that CO2 emission has a severe effect on Korean power system. Therefore, as the most important issue, the generation expansion planning considering environmental constraints is rising in power system. This paper develops a mathematic model including not only generation expansion planning but transmission planning and considering regional supply-demand and environmental constraints, especially CO2 emission, and verifies propriety through the case study.

• 대한기계학회논문집A
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• 제33권1호
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• pp.42-48
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• 2009

A design methodology for control strategy and control structure gives a direct impact on wind turbine's performance and life cycle. A baseline control law which is a variable rotor speed and variable pitch control strategy is introduced, and a mathematic performance model of a wind turbine dynamics is derived. By using a numeric optimization algorithm, the steady state operating conditions of wind turbines are identified. Because aerodynamic interaction of winds with rotor blades is basically nonlinear, a linearization procedure is applied to analyze wind turbine dynamic variations for whole operating conditions. It turns out the wind turbine dynamics vary much depending on its operating condition.

• 대한수학교육학회지:학교수학
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• 제3권1호
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• pp.45-74
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• 2001

In this paper, an analysis of survey questions relating to educational technology which was extracted from a more general survey of 1-12 mathematics teachers in Korea is reported. The general survey was conducted to provide a baseline for evaluating and developing recommendations for mathematics curriculum that is consistent with the knowledge based information society model of the future. The basic requirements for technology based education are availability of hardware and the ability of teachers to use technology for education. Therefore, the availability and use of technology by mathematics teachers in today’s curriculum was analyzed. The computer ability of teachers, the amount of computer use in the classroom, and the attitude of teachers about the use of technology for education was analyzed. The analysis is intended to provide a baseline of information for understanding and developing plans for better implementing technology for mathematic education.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.563-566
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• 2002

This paper presents the modeling and analysis of wind turbine generating system(WTGS) using doubly fed induction machine as a generator Generally, wind turbine generating system is composed of complicated machinery. So it is very difficult to present the mathematic model. This means that WTGS has a nonlinear system. Using the real output data from the WTGS for one year, it is simply possible to express the rotor and gear coupling system as a torque generator according to wind speed. Also, the modeling of electrical system can be able to present using the data sheet from the company. To analyze the proposed method, computer simulation using Psim program are presented to support the discussion.

• 대한수학교육학회지:학교수학
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• 제4권4호
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• pp.539-554
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• 2002

Mathematics is constructed by many signs, and learning mathematics involves the understanding and uses of them. This study reflects mathematical signs and their meanings, and considers how they can be introduced in learning. For these, we first investigated epistemological positions as Piaget, Vygotsky, anthropology, and interactionism. And we investigated semiotic models that Saussure and Peirce built each. Among these we adopted Peirce' triadic model that is consisted of interpretant, object (referent), and represen tamen(sign). In mathematic learning process, representations are transformed by translations and meanings are growed to the representation of another sign. And the meaning of sign grows by learner's interpretation. In terms of theoretical grounds, we settled that the understanding of mathematical signs involved the understanding of their representations and their meanings. On the foundation of above contents, we searched how we introduced signs to students and there were methods that approached to students representationally or inquiringly.