• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.87-97
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• 2008

The purpose of this study is to analyse and compare experimentally flexural behavior of RC beams strengthened with CFRP plates by different methods, and finally develop the nonlinear analysis model with the aim of predicting the improving effects of structural capacity and the structural behaviors of RC beams. From this study, the characteristics of bond and flexural behavior of the prestressed CFRP plates were analyzed and examined. In deed, the beams were tested with experimental parameters of strengthening methods and prestressing level, and the developed analysis model was evaluated with the testing results. From this study, it is concluded that the developed analysis model have a good reliability and can be applied to the strengthening design of beams using CFRP plates.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.975-982
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• 2024

This paper optimally designs the shape of the rotor notch to improve the efficiency and reduce torque ripple of a 30kW EV traction IPMSM. To improve torque ripple, notches were applied to the IPMSM rotor and the optimal design was performed. Elliptical, square, and triangular notches were applied to the IPMSM rotor and sample points of the IPMSM were generated within the specified design range using OLHD. Fifty sample points were generated for each of the three types of notches, and five metamodels were generated. The model with the lowest RMSE among the generated metamodels was selected, and parameter sensitivity analysis and optimal design were performed using this. The results of the optimal design were verified by FEA and compared with the torque characteristics of the existing IPMSM. As a result, the torque ripple was reduced by 62.5% to 1.376Nm compared to the initial model, the peak-to-peak cogging torque was reduced by 34% to 0.547Nm, and the efficiency was 96.742%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.1-9
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• 2004

This study concentrates on the upwind schemes for convergence acceleration of the multigrid method for the Navier-Stokes equations. Comparative study of the upwind schemes in the Fourier space has been performed to identify why the second-order upwind scheme with enlarged stencil can be preconditioned better than the classical second-order upwind scheme. The full-coarsening multigrid method with implicit preconditioned multistage scheme has been implemented for verification of analysis. Numerical simulations on the inviscid and turbulent flows with the Spalart-Allmaras turbulent model have been performed. The results showed consistent trend with the analysis.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.132-137
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• 2017

This paper proposes a transformation method of the zero moment point (ZMP) and the center of mass (CoM) from one walking pattern to other patterns by considering the structure of a robot or walking situations in real time. In general, a humanoid robot has own structure characteristics like height and mass. The structure characteristics make the given CoM/ZMP walking pattern of one human or one humanoid robot to be difficult to apply to other robot directly. For this purpose, we analyze the characteristics of walking patterns according to the step length, duration of walking support phase and the CoM height by using the cart-table model as the simple humanoid robot model. A transformation equation is derived from the analyzation and it is verified with simulation.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.483-489
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• 2006

The purpose of this study is to suggest logical foundation and points which are necessary for establishing E-commerce cf Korean shipping companies' development strategy and activation plan. In order to do empirical analysis, two step analyses are adopted. Firstly, this study examines the effects of the shipping company character and the shipping environment character on the usage of E-commerce in the shipping companies. Secondly, this study examines the effects of usage of E-commerce on the performance in shipping companies. In the empirical analysis, research hypotheses are being tested mainly by a structural equation model(SEM).

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.208-208
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• 2011

우리나라의 하천은 산악지역이 많은 지형적인 특성상 만곡이 많은 산지하천의 특성을 가지고 있다. 따라서 집중호우가 많이 발생하는 홍수시에는 급격한 수위상승과 함께 하천 인근 지역에서 많은 재해가 발생하게 된다. 본 연구에서는 남한강의 지류인 평창강의 수리 수문의 경향성을 분석하고, 만곡부에서의 수리학적 특성을 분석하기 위해 평창강 상류에 위치한 지방하천인 속사천과 흥정천 합류부를 중심으로 4곳의 수위관측소에서 유량측정을 실시하였으며, 속사천의 2개 지점과 흥전천의 2개 지점의 만곡부에서 홍수시 수위상승으로 인한 편수위를 측정하고자 하였다. 수위관측소는 속사천에 장평교와 의풍포교 관측소가 있으며, 흥정천에 백옥포 관측소 그리고 합류부 이후에 평창강의 상안미 관측소가 있다. 본 연구에서는 2010년 3월부터 12월까지 측정된 유량측정 자료의 정량적 분석과 불확실도 해석을 실시하여 시험유역 운영 자료에 대한 정확성을 분석하고자 하였다. 이와 같은 시험유역의 운영은 유역의 수문순환 특성분석의 순환구조의 이해와 모델개발 검정 및 검증 기반의 자료를 구축하여 산지지형의 해석을 위한 기초자료로 활용할 수 있을 것이다.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.339-345
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• 2010

This study has purpose of minimizing damage from fire incident as analyzing the fire characteristic about fire incident of multi-use hostels, which is increasing recently. For this, CFAST, a verified analysis program for the fire incident was employed to prove the logicality of the study by comparing with a established result of the research work and working the fire simulation for an apartment house. On the basis of this, the study will help to improve safety of fire by analyzing the fire characteristic of Karaoke and Gosiwon which are typical model of multi-use hostels and by establishing how to deal with the fire incident.

• Journal of the Korean Magnetics Society
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• v.26 no.3
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• pp.81-85
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• 2016

This paper introduces a performance integration method to predict variation characteristic of a performance function of electromagnetic machines or devices due to manufacturing tolerances. A normalized performance function space and a hybrid mean value technique are adapted to effectively predict mean and variance, which can identify probabilistic distribution of the performance function. To verify the effectiveness and accuracy of the proposed method, a mathematical problem and a loudspeaker model are tested, and numerical results are compared with those of existing methods such as Monte Carlo simulation and univariate dimension reduction method.

• Journal of the Korean Magnetics Society
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• v.6 no.5
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• pp.281-286
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• 1996

For the accurate analysis of motional characteristics of electrical machines, it is needed to solve the motion equations together with the electromagnetic field equations. In this paper the sequential coupling of systems, the spring mass system and the electromagnetic system, is adopted. The induced current and the magnetic fields are calculated by finite element method(FEM) with given speed. And then, with the computed elec-tromagnetic force, the mechanical equations are solved by the Runge-Kutta method. The above two processes are repeated sequentially to obtain the time domain solutions. The resultant values are applied to the energy conservation law to prove the usefulness of the proposed sequential method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.97-103
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• 2004

Nowadays, many kinds of research for airship are studying with increasing of interests of airship. But these are far from perfect. The data acquisition from the actual flight test has lots of difficulties because of the characteristics from the slow dynamic response and high sensitivity for external environment. In this paper, through the actual flight test, appropriateness of the mathematical dynamic model applied here was verified by comparing the test data with simulation data in same control conditions.