• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.187-188
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• 2009

본 연구는 유한요소해석을 통해 I-슬래브의 내력 및 거동을 예측하기 위한 기초자료를 제시하는 데에 그 목적을 두고 있다. 2개의 실험체를 선정하고 해석을 위한 3차원 모델을 작성하여 해석을 수행하여 해석 결과와 실험 결과의 비교를 통해 해석모델의 적합성을 검토하였다.

• 한국건축시공학회지
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• 제12권5호
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• pp.528-538
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• 2012

With domestic construction projects becoming bigger, more specialized and more advanced, the construction industry is striving to improve quality and quantity, and is diversifying functions and shapes. Nevertheless, the process of a construction project causes problems when we estimate construction price, because the cost breakdown structures are different in each step. The primary aim of this study was to estimate building life cycle cost using the Delphi method. The cost breakdown structure for life cycle cost was classified into planning, design, construction, maintenance and waste disposal, and each detailed classification was determined by estimating life cycle cost. Moreover, the developed cost breakdown structure is verified by consulting with experts to secure objectivity and validity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1656_1657
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• 2009

This paper presents a new method for estimating rotor resistance of induction motor. The rotor resistance changes dramatically with temperature and frequency. Speed is controlled by PID as it is simplest and most intuitive control method. The change in rotor resistance has a great influence on the performance of IM. In this paper rotor resistance is estimated using Non Linear Disturbance Observer. The model uncertainty and system non linearity are treated as disturbance in this method. Using NDO it does not require an accurate dynamic model to achieve high precision motor control. Controller with NDO has more superior tracking performance. Simulation results are presented to show the validity of the proposed controller.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.619-628
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• 2015

In this paper, we consider a method for estimating a stripe-type defect and the reconstruction of a defect-free L/S type mask used in lithography. Comparing diffraction patterns of defected and defect-free masks, we derive equations for the estimation of the location and size of the defect. We construct an analytical model for this problem and derive closed form equations to determine the location and size using phase retrieval problem solving techniques. Consequently, we develop an algorithm that determines a defect-free mask pattern. An example shows the validity of the equations.

• Journal of applied mathematics & informatics
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• 제23권1_2호
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• pp.57-71
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• 2007

This paper considers how to detect structure change in persistence from I(1) to I(0) with innovations in the domain of attraction of a K-stable law. We derive the asymptotic distribution of test statistic and find that the asymptotic distribution of test statistics depends on the stable index K, which is often typically unknown and difficult to estimate. Therefore the subsampling method is proposed to detect changes without estimating K. We establish the asymptotic validity of this method and assess its performance in finite samples by means of simulation study.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.749-754
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• 1989

This paper describes a remote measurement method for estimating unsteady flowrate through a pipeline. By this method, instantaneous flowrate at the remote location along a pipeline (distance L) from flowmeters is measured by making use of dynamic characteristics between two cross sections of the circular pipeline. Using this method, instantaneous flowrate is accurately measured at a location where it is difficult to setup flowmeters. The estimated flowrate waveforms by the method are compared with directly measured ones by cylindrical choke-type instantaneous flowmeter. The validity of the method is established.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1124-1127
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• 2003

This paper proposes a sensorless vector control of interior permanent magnet synchronous motor(IPMSM) using a Luenberger observer. Linearizeng the motor model, we can construct the linear reduced order observer for estimating rotor position and disturbance torque. The validity of the proposed scheme is confirmed by various response characteristics.

• 벤처창업연구
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• 제2권2호
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• pp.49-68
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• 2007

본 연구는 인터넷 쇼핑몰 창업 시 활용할 수 있는 비즈니스 모델 사전 자가 평가 방법론을 개발하는 것이다. 자가 평가 방법론은 Bruce Merrifield 박사가 제안한 BMO 모형을 인터넷 쇼핑몰에 맞도록 재구성하였으며, 평가 항목이 변형을 위해 인터넷 비즈니스의 특징, 인터넷 비즈니스 모델의 사업성 평가에 관한 이론, e-business의 성공 실패요인, 벤처기업의 성공 실패요인, 기술가치 평가 요인, 인터넷 쇼핑몰의 성공 실패요인 등에 관한 선행연구들을 고찰하였다. 재구성된 사업매력도 평가항목은 매출규모, 시장성장성, 경쟁력, 위험분산도, 업계 재구축 가능성, 특별한 사회적 상황이며, 자사회의 적합성 평가항목은 경영자특성, 컨텐츠제공력, 상호작용성 구현 및 운영, Commerce, Fulfillment, 마케팅력이다. 재구성된 BMO모형으로 인터넷 쇼핑몰 사업을 진출하고자 하는 I사, D사, G사를 대상으로 사례연구를 하였다. 본 연구는 자가평가를 통한 부적격한 인터넷 쇼핑미로 비즈니스 모델의 사업화 방지, 인터넷쇼핑몰 비즈니스 모델의 평가를 통해 사업을 점검하고 실행할 수 있는 지침 제공, 인터넷 쇼핑몰 비즈니스 모델이 실행에 필요한 자원의 수준과 확보의 용이성 평가에 활용될 수 있다.

• 한국정보통신학회논문지
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• 제16권6호
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• pp.1235-1241
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• 2012

본 논문에서는 4족 보행로봇 TITAN-VIII의 모든 관절각과 로봇 본체의 자세각을 계측하여 발바닥의 위치를 추정하고 각 관절의 구동모터를 제어하였다. 네 발바닥에 로드셀을 설치하여 주기, 한주기당 이동거리와 발바닥이 들어 올려지는 높이를 변경하여 8가지 서로 다른 조건에서 보행실험을 수행하고 보행 중 발바닥에 가해지는 힘과 각 관절을 구동하는 모터의 소비전력을 구한 후 비교 분석하여 자세제어의 타당성을 평가하였다. 분석결과 새로운 주기가 시작되는 구간에서 발바닥이 지면을 늦게 떠나는 슬립현상을 확인했는데 이것은 관절각과 본체의 자세각을 계측하여 발바닥의 위치를 추정하고 보행계획을 수립하여 제어하는 것만으로 보행 중 발생하는 로봇 본체의 기울어짐과 기계적인 에러를 완벽하게 극복하지 못함을 확인했다.

• Computers and Concrete
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• 제23권3호
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• pp.161-170
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• 2019

This paper aims at presenting a numerical method for estimating the elastic modulus of recycled concrete with crushed aggregates. In the method, polygonal aggregates following a given sieve curve are generated, and placed into a square simulation element with the aid of the periodic boundary condition and the overlap criterion of two polygonal aggregates. The mesostructure of recycled concrete is reconstructed by embedding an old interfacial transition zone (ITZ) layer inside each recycled aggregate and by coating all the aggregates with a new ITZ layer. The square simulation element is discretized into a regular grid and a representative point is selected from each sub-element. The iterative method is combined with the fast Fourier transform to evaluate the elastic modulus of recycled concrete. After the validity of the numerical method is verified with experimental results, a sensitivity analysis is conducted to evaluate the effects of key factors on the elastic modulus of recycled concrete. Numerical results show that the elastic modulus of recycled concrete increases with the increase of the total aggregate content and the elastic moduli of old and new ITZ but decreases with increasing the replacement ratio of recycled aggregate and the thicknesses of old and new ITZ. It is also shown that, for a replacement ratio of recycled aggregate smaller than 0.3, the elastic modulus of recycled concrete is reduced by no more than 10%.