• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.1-3
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• 2019

본 논문에서는 전차원 관측기를 이용한 유도기의 센서리스 운전에서 제정수 오차가 제어 성능에 미치는 영향을 수식적으로 분석하였다. 주파수 응답 함수를 이용해 실제 자속과 추정 자속의 관계를 운전 속도와 슬립 주파수의 함수로 나타내었다. 적응(adaptive) 법칙을 이용하여 추정 속도를 수식에서 제거하였다. 또한 각오차가 존재하는 상황에서 전류 운전점 변화를 고려하여 슬립 주파수를 토크 지령으로 변환하였다. 결과적으로 모든 운전 속도와 토크 지령에 대해서 임의의 제정수 오차가 시스템의 안정도, 속도 오차 및 토크 오차에 미치는 영향을 계산할 수 있는 수식을 구하였다. 기존의 분석 방법들이 많은 시뮬레이션과 실험을 통해 제정수의 영향을 평가했던 것과 달리, 구해진 수식에 근거하여 계산을 통해 빠르게 주어진 센서리스 운전 방법을 평가할 수 있는 방법을 제공하였다. 제안된 분석 방법은 시뮬레이션과 실험을 통해 검증되었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.886-890
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• 2011

Induction motors are relatively cheap and rugged machines. For the vector control of induction motors, a position or speed sensor is needed. But a speed sensor increases motor cost and reduces reliability in harsh environment. Recently, many studies have been performed for sensorless speed control. This paper investigates an improved flux observer with the parameter error compensation for a sensorless induction motor. The proposed algorithm is verified through simulation and experiment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.6
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• pp.409-416
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• 2019

An improved numerical model for non-linear analysis of reinforced concrete (RC) slabs subjected to blast loading is proposed. This approach considers a strain rate dependent orthotropic constitutive model that directly determines the stress state using the stress-strain relation acquired from the data obtained using the biaxial strength envelope. Moreover, the bond-slip between concrete and reinforcing steel is gradually enlarged after the occurrence of cracks and is concentrated in the plastic hinge region. The bond-slip model is introduced to consider the crack direction of the concrete under a biaxial stress state. Correlation studies between the numerical analysis and the experimental results were performed to evaluate the analytical model. The results show that the proposed model can effectively be used in dynamic analyses of reinforced concrete slab members subjected to explosive loading. Moreover, it was determined that it is important to consider biaxial behavior in the material model and the bond-slip effect.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.51-57
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• 2011

Information of the lateral velocity and the sideslip angle in a vehicle is very useful in many active vehicle safety applications such as yaw stability control and rollover prevention. Because cost-effective sensors to measure the lateral velocity and the sideslip angle are not available, reliable algorithms to estimation them are necessary. In this paper, a sliding mode observer is designed to estimate the lateral velocity. The side slip angle is estimated using the recursive least square with the disturbance observer and the pseudo integral. The estimated parameters from the combined estimation method are updated recursively to minimize the discrepancy between the model and the physical plant, and any possible effects caused by disturbances. The performance of the proposed monitoring system is evaluated through simulations and experiments.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.65-66
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• 2017

본 논문은 자기부상열차 시스템의 부상 신뢰도 향상을 위한 선형 유도전동기의 순시 제어기법을 제안한다. 선형 유도전동기는 자기부상열차의 추진을 담당하며, 운전 속도와 입력 주파수에 따른 슬립 특성이 존재한다. 이 슬립 특성은 전동기에서 발생되는 수직력과 밀접한 관련을 보이며, 이는 부상 시스템에 외란으로 작용된다. 따라서 본 논문에서는 선형 유도전동기의 특성을 FEM 해석을 통해 정확히 분석하고, 이를 반영한 최적 슬립 주파수 간접벡터제어 기법을 통해 부상 신뢰도 향상을 위한 새로운 순시 제어기법을 제안 하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.60-60
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• 2004

광디스크 미디어 저장기기에 있어서 음악과 영상을 재생하는 광디스크 플레이어의 기구부품 중 턴테이블은 디스크를 장착, 고정하여 디스크에 기록된 신호를 재생케 하는 광디스크 메커니즘의 중요기능 부품이다. 특히 별도의 클램퍼 없이 턴테이블에 부설된 탄지력만으로 디스크를 장착, 고정하는 슬림형 플레이어에서 스핀들 모터의 회전 시 턴테이블에 장학된 광디스크의 슬립은 재생에러를 야기한다. 스피닝 회전속도가 증가할수록 디스크의 슬립을 방지하기 위해서는 디스크와 턴테이블의 증가된 마찰력이 요구된다.(중략)

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.207-213
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• 1999

In this study, the possibility of estimation of friction coefficient between tire and road surface using running car data are checked. To get necessary data, such as tire and car velocities and braking force, a test car is driven with certain magnitude of decelerations from pre-set initial velocities to stop . The data are used to estimate friction coefficient with property chosen parameters , e.g,, driving stiffness, pressure distribution functions, etc. Experimental results show that running data car be used with properly chosen parameters to estimate friction coefficient.

• Journal of Korean Society of Steel Construction
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• v.16 no.6 s.73
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• pp.747-757
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• 2004

With steel and concrete composite beams, the incomplete interaction between the steel and the concrete slab leads to an appreciable increase in beam deflections. Moreover, encased composite beams using a deep deck plate or hollow-core PC slabs are critical to deflection due to their inherent geometry. In this paper, by using the calculation tools that were developed for a previous study on the deflection of encased composite beams considering the slip effects and load-slip curve, the shear bond stress and additional deflection induced due to interface slip of the encased composite beam are presented. It was found that the slip effects significantly contribute to the encased composite beam deflections and result in stiffness reduction of up to 30% compared to that of full shear interaction beams. The predicted results were compared with the measurement of 18 specimens tested in this study, and comparisons show a high degree of accuracy, within 6%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.90-97
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• 2002

Wall slip models are essential to the study of nonequilibrium gas transport in rarefied and microscale condition that can be found in gas flows associated with aerospace vehicle, propulsion system, and MEMS. The Maxwell slip model has been used for this type of problem, but it has difficulty in defining the so-called accommodation coefficient and has not been very effective in numerical implementation. In the present study, on the basis of Langmuir's theory of the adsorption of gases on metals, a physical slip model is developed. The concept of the accommodation coefficient and the difference of gas particles are clearly explained in the new model. It turned out that the Langmuir model recovers the Maxwell model in the first-order approximation. The new models are also applied to various situations including internal flow in a microchannel. Issues of validation of models are treated by comparing analytic results with experiment.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.2
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• pp.7-12
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• 2011

Presently, composite method for steel and concrete is often used the stud. Steel properties of composite column could be changed by increasing of welding. The changed properties is possibly to cause local-buckling. Composite column had a large effect by slip instead of pull-out force in comparison composite girder. Improvement of adhesive force had effect by contact area rather than height of stud in composite column. This paper proposed new type of stud and analyzed performance through experimental study. This method would be effect steel structure with curvature.