• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.155-160
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• 2002

This study is performed to analyze of reinforced concrete beams under fire and to calculate remaining strength. The analysis is based on the assumption that plane section remains plane after bending due to load and non-linear temperature increases. Finite difference method is used to find temperature field in a section. The residual strength is attained considering the effect of temperature rise on the mechanical properties of concrete, self-equilibrium stress and reduced section. Further research in much needed on the material models of concrete since it governs temperature distribution and theoretical results.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.403-405
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• 1988

Recently, Power change devices using thyristor and transistor have grown with the rapid development of power electronics. But the devices using these semiconductors generate harmonics from the non-linear load, which gives rise to various obstacles. In this paper, therefore, as 3 taps are connected in input line, we can multiply the pulse in input line, by which harmonics is reduced.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.519-524
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• 1999

A bulb-tee sectioned girder is proposed for long span bridge exceeding 40 meters. The proposed bulb-tee girder is developed by non-linear analysis process. This study investigates the structural behavior and efficiency of proposed bulb-tee sectioned girder using 1/2 scaled prototype beam specimen. Three specimens are tested under three point static loading system. The crack patterns, failure mode and ultimate load capacity of each specimen are reported in this paper and they are compared to each other.

• 전기의세계
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• v.22 no.4
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• pp.11-16
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• 1973

This paper presents an optimum control of the field resistance for the self-excited DC shunt generator to keep a constant terminal voltage in case of the load change or the torque variation in the system. The non-linearity of the system is linearized by applying the small signal technique and the linearized equation is solved by the maximum principle with the digital computer. The optimal control value of the field resistance for the step error of the generator output voltage is obtained and the transient voltage characteristics in the system are investigated.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.47-49
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• 2005

This paper presents a robust speed control method of induction motors(IM) using a Non-linear PI controller(NPI), NPI is high gain controller in region of small error, and low gain controller in region of large error. so in steady state, system will be robust against variation of load torque. The simulation and experiment results confirm the validity of proposed control scheme.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.227-231
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• 2006

This paper presents a robust speed control method of induction motors(IM) using a Non-linear PI controller(NPI). NPI is high gain controller in region of small error, and low gain controller in region of large error. So in steady state, system will be robust against variation of load torque. The simulation and experiment results confirm the validity of proposed control scheme.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.199-201
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• 2002

This paper showed that there exists a non-linear relationship between MVAR and MW, and the rage of the threshold value of MVAR is 56 to 67. Also, we tried the one-hour ahead forecasting model of MVAR using the MW as the explanary variable.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.222-223
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• 2016

본 논문에서는 계통연계 인버터에서 비선형부하의 위치에 따라서 발생되는 고조파를 보상하기위한 전류제어 방식을 사용하였다. 비선형부하로 인해 발생되는 고조파는 계통 전압 및 전류의 THD에 많은 영향을 미치기 때문에 이를 보상하는 것이 본 논문의 목적이다. 비선형부하의 위치에 따라서 각각의 경우에 대해 두가지의 고조파 지령값을 선택하는 방식을 사용하였다.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.171-172
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• 2015

본 논문은 변압기에 부하가 연결 되었을 때 발생하는 전류 고조파에 의한 변압기 손실을 분석한다. 3상 변압기에 대해서 선형 부하와 비선형 부하가 연결되었을 경우 변압기 손실 값을 계산한다. PSIM을 이용하여 부하를 모델링하고 시뮬레이션 수행한다. 시뮬레이션을 통하여 얻어진 데이터를 이용하여 변압기의 손실값을 계산한다.

• Computers and Concrete
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• v.20 no.4
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• pp.369-380
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• 2017

The effects of the vertical component of a ground motion on the earthquake performances of semi-ductile high-rise R/C structures were investigated in the present study. Linear and non-linear time-history analyses were conducted on an existing in-service R/C building for the loading scenarios including and excluding the vertical component of the ground motion. The ratio of the vertical peak acceleration to the horizontal peak acceleration (V/H) of the ground motion was adopted as the main parameter of the study. Three different near-source earthquake records with varying V/H ratio were used in the analyses. The linear time-history analyses indicated that the incorporation of the vertical component of a ground motion into analyses greatly influences the vertical deflections of a structure and the overturning moments at its base. The lateral deflections, the angles of rotation and the base shear forces were influenced to a lesser extent. Considering the key indicators of vertical deflection and overturning moments determined from the linear time-history analysis, the non-linear analyses revealed that the changes in the forces and deformations of the structure with the inclusion of the vertical ground motion are resisted by the shear-walls. The performances and damage states of the beams were not affected by the vertical ground motion. The vertical ground motion component of earthquakes is markedly concluded to be considered for design and damage estimation of the vertical load-bearing elements of the shear-walls and columns.