• 한국조명전기설비학회지:조명전기설비
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• 제9권4호
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• pp.86-92
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• 1995

In the analysis of characteristic behaviors of a real transformer with coupling coefficient K is less than 1, this paper presents the more accurate and practical profits than the traditional analysis of the transformer treated as K∼1. This results from the use of the coupling coefficient type equivalent circuit of the transformer which includes K as positive parameter. Furthermore, a leakage transformer is analyzed in a unified method and the results of analysis are consistent with the practical measurements of the transformer. By using the above equivalent circuit, the characteristics referred to the load side are expressed as Thevenin voltage source and the leakage inductor (1-K2)L2. Therefore, these analysis about the output voltage and the damping factor in the transient state which are affected by the leakage inductor are confirmed to be an effective method.

• 한국안전학회지
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• 제31권5호
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• pp.149-157
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• 2016

This paper presents the traffic speed limit of heavy vehicles at each wind velocity region, which is based on their accident risk analysis under cross-wind. The variables for the accident risk analysis are overall height, overall length, intake weight, and friction coefficient of the road surface. It was confirmed from analysis results that the risk of overturning increased with higher overall height and length, and the risk of sliding decreased with higher intake weight. The risk of sliding was largest at the friction coefficient of 0.1, and the risk of overturning was lagest at friction coefficient more than 0.25. Finally, traffic speed limit was proposed by using the accident risk analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.426-431
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• 1998

This, paper describes formulation for time historical response analysis of vibration for tree structure. This method is derived from a combination of the transfer stiffness coefficient method and the Newmark-.betha. method. And This present method improves the computational accuracy of the transient vibration response analysis remarkably owing to several advantages of the transfer stiffness coefficient method. We regarded the structure as a lumped mass system here. The analysis algorithm for the time historical response was formulated for the tree structure. The validity of the present method compared with the transfer matrix method and the FEM(Finite Element Method) for transient vibration analysis is demonstrated through the numerical computations.

• Earthquakes and Structures
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• 제10권4호
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• pp.913-938
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• 2016

'Stepped building' frames, with vertical geometric irregularity, are now increasingly encountered in modern urban constructions. This paper proposes a new approach to determine the lateral load pattern, considering the contributions from the higher modes, suitable for pushover analysis of stepped buildings. Also, a modification to the displacement coefficient method of ASCE/SEI 41-13 is proposed, based on nonlinear time history analysis of 78 stepped frames. When the newly proposed load pattern is combined with the modified displacement coefficient method, the target displacement for the stepped building frame is found to match consistently the displacement demand given by the time history analysis.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.39-44
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• 2012

This paper deals with the characteristic analysis of small power brushless DC (BLDC) motor considering the rotor magnet overhang flux. In the driving characteristics analysis using 2D FEA (Finite Element Analysis), the rotor magnet overhang effect can't be considered and it should be neglected. To consider rotor magnet overhang effect, 3D FEA should be required. But 3D FEA requires very long calculation time even though the high specification computer is used. In this paper, the 3D electromagnetic model of BLDC motor is approximated as the 2D electromagnetic model considering overhang effect. In this paper, the concept of overhang coefficient is applied, and the coefficient according to load torque variance is deduced.

• 동력기계공학회지
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• 제1권1호
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• pp.91-97
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• 1997

Recently, it is increased by degrees to construct complex and large structures. In general, in order to solve the dynamic problem of these structures they have used finite element method(FEM). In this method, however, it is necessary to prove whether its results are correct or not. Therefore it requires much effort, time and many expenses for dynamic analysis of complex and large structures. Authors have developed the transfer dynamic stiffness coefficient method(TDSCM) which is the new vibration analysis method for complex and large structures on personal computer, and confirmed that the results of this method are good for these structures on personal computer. In this paper, TDSCM is applied to the torsional vibration analysis for the shaft system which consist of concentrated disks and shafts of continuous body. First, we formulate algorithms for torsional free and forced vibration analysis, and compare the results of TDSCM and FEM.

• Journal of Welding and Joining
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• 제20권3호
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• pp.129-137
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• 2002

This study presents a new method to derive the constraint coefficient from the degree of angular deformation caused by welding, as measured experimentally by varying the shape of welded joints and the magnitude of constraints and from analysis results given by the elastic FEM method. The equivalent load was then calculated with this constraint coefficient. The validity of the numerical analysis involved in this new method was confirmed by its agreement with the experimental results. As for the effects of the constraints based on the shape of the welded joints in the case of Butt welding when the constraint coefficients are not considered, the deformed quantity produced by analysis is larger that produced by experiment and consequently is largely affected by the constraints. However, in the case of Fillet welding, the deformed quantity is seldom affected regardless of constraint coefficient considerations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.477-482
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• 1989

In this paper, the effect of coefficient quantization error is analyzed for digital PID controllers. Stability margins are used as peformance criteria, and the statistical wordlength concept is adopted for coefficient wordlength selection. Finally, an illustrative example is given.

• 한국농공학회논문집
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• 제63권6호
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• pp.39-47
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• 2021

Reduction effect of the spread of odorant and fine dust through windbreak trees can be predicted through numerical analysis. However, there is a disadvantage that a large space and destructive experiments must be carried out each time to calculate the aerodynamic coefficient of the tree. In order to overcome these shortcomings, In this study, we aimed to estimate the aerodynamic coefficient (C₀, C₁, C₂) by using image processing. Thuja occidentalis, which can be used as windbreak were used as the material. The leaf area index was estimated from the leaf area ratio using image processing with leaf weight, and the optical porosity was calculated through image processing of photos taken from the side while removing the leaves step-by-step. Correlation analysis was conducted with the aerodynamic coefficient of Thuja occidentalis calculated from the wind tunnel test and leaf area index and optical porosity calculated from the image analysis. The aerodynamic coefficient showed positive and negative correlations with the leaf area index and optical porosity, respectively. The results showed that the possibility of estimating the aerodynamic coefficient using image processing.

• 한국지반공학회논문집
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• 제36권11호
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• pp.7-20
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• 2020

본 연구에서는 말뚝기초를 대상으로 지반조건을 고려한 동적 수평지반반력계수를 제안하기 위하여 수치해석을 수행하였다. 3차원 유한차분 프로그램을 사용하여, 다양한 지반의 전단파 속도에 따라 동적수치해석을 수행하였다. 수치해석 결과로부터 동적 p-y 곡선을 도출하여 동적 수평지반반력계수를 계산하는 데 필요한 보정계수(α)를 산정하였다. 분석결과, 본 연구에서 산정된 보정계수(α)는 기존 도로교 설계기준(2015)에 제시된 획일적인 값(α=2)이 아니라 지반의 전단파 속도와 구속압에 매우 큰 영향을 받는 것을 알 수 있었으며 이를 고려한 함수식으로 제안하였다. 제안된 α의 적용성 분석을 위해 서로 다른 해석 기법(등가정적해석방법과 동적해석방법)에서의 적용성을 비교하였다. 그 결과, 제안된 보정계수(α)를 사용하는 방법은 기존 동적 수평지반반력계수를 사용하는 방법에 비해 지반-말뚝 시스템의 수평거동 특성을 비교적 적절하게 예측함을 알 수 있었다.