• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.123-126
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• 2001

This study presents the simulation of the traction return current based on 2${\times}$25kV power supply system in order to determine the impedance bond intensity of impulse type track circuit on the Kyoungbo electrification line. The results of simulation enables us to measure the precise intensity of catenary current, returning to the substation through KTX (Korean Train Express) operated by 2${\times}$25kV power supply system with common earth network. In the wake of establishing 2${\times}$25kV and common earth network used in Korea for the first time, in particular, it is possible to determine the impedance bond intensity of impulse type track circuit, which is applicable to the Kyoungbo electrification line by specifying the relations among the traction return current, earth current, and catenary current.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1207-1214
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• 2001

The paper deals with the computational approach in analysis and design of pantograph panhead strips of high-speed railway in aerodynamic and aeroacoustic concerns. Pantograph is an equipment such that the electric power is supplied from catenary system to train. Due to the nature of complexity in high-speed fluid flow, turbulence and downstream vortices result in the instability in the aerodynamic contact between panhead strips and catenary system, and consequently generate the considerable levels of flow-induced sound. In this paper, based on the preceding low speed wind-tunnel test and simulations, the aerodynamic and aeroacoustic characteristics in low speed are analyzed.

• International Journal of Precision Engineering and Manufacturing
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• 제5권4호
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• pp.50-60
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• 2004

A very flexible beam can be used to model various types of continuous mechanical parts such as cables and wires. In this paper, the dynamic properties of a very flexible beam, included in a multibody system, are analyzed using absolute nodal coordinates formulation, which is based on finite element procedures, and the general continuum mechanics theory to represent the elastic forces. In order to consider the dynamic interaction between a continuous large deformable beam and a rigid multibody system, a combined system equations of motion is derived by adopting absolute nodal coordinates and rigid body coordinates. Using the derived system equation, a computation method for the dynamic stress during flexible multibody simulation is presented based on Euler-Bernoulli beam theory, and its reliability is verified by a commercial program NASTRAN. This method is significant in that the structural and multibody dynamics models can be unified into one numerical system. In addition, to analyze a multibody system including a very flexible beam, formulations for the sliding joint between a very deformable beam and a rigid body are derived using a non-generalized coordinate, which has no inertia or forces associated with it. In particular, a very flexible catenary cable on which a multibody system moves along its length is presented as a numerical example.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1347-1352
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• 2004

• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.209-217
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• 2013

This paper presents a mooring design procedure for a floating offshore wind turbine. Offshore environmental data for Jeju are taken from KHOA (Korea Hydrographic and Oceanographic Administration) and used for the environmental conditions in numerical analyses. A semi-submersible-type floating wind system with a 5-MW-class wind turbine studied by the DeepCwind Consortium is applied. Catenary mooring with a studless chain is chosen as the mooring system. Design deliverables such as the nominal sizes of chain and length of the mooring line are decided by considering the long-term prediction of the breaking strength of the mooring lines where a 100-year return period is used. The designed mooring system is verified using a fatigue calculation based on rain-flow cycle counting, an S-N curve, and a Miner's damage summation of rule. The mooring tension process is obtained from time-domain motion analyses using ANSYS/AQWA.

• Coupled systems mechanics
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• 제1권3호
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• pp.247-268
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• 2012

A finite element model is developed for dynamic response prediction of floating offshore wind turbine systems considering coupling of wind turbine, floater and mooring system. The model employs Morison's equation with Srinivasan's model for hydrodynamic force and a non-hydrostatic model for restoring force. It is observed that for estimation of restoring force of a small floater, simple hydrostatic model underestimates the heave response after the resonance peak, while non-hydrostatic model shows good agreement with experiment. The developed model is used to discuss influence of heave plates and modeling of mooring system on floater response. Heave plates are found to influence heave response by shifting the resonance peak to longer period, while response after resonance is unaffected. The applicability of simplified linear modeling of mooring system is investigated using nonlinear model for Catenary and Tension Legged mooring. The linear model is found to provide good agreement with nonlinear model for Tension Leg mooring while it overestimates the surge response for Catenary mooring system. Floater response characteristics under different wave directions for the two types of mooring system are similar in all six modes but heave, pitch and roll amplitudes is negligible in tension leg due to high restraint. The reduced amplitude shall lead to reduction in wind turbine loads.

• 전기학회논문지
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• 제64권12호
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• pp.1818-1823
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• 2015

In this paper, we analyzed the optimal configuration of protection wire that have been installed in the electric railway power supply system. Protection wires are to suppress the ground potential rise when the short circuit fault between contact wire-rail(C-F), and protect the electronics equipments(signalling and communication) that are facility the wayside. The role of protection wires must be feed back quickly the fault current to the substation when a short circuit fault occurs. In this paper, we proposed that only one line to install the protection wire. Comparing how to newly proposed and existing system, most of the performance is similar. The reason is that most of the current flowing in the protection wire near the location where the fault occurred. There is no problem even if in one line for human safe and the low impedance of the return circuit in dimension to ensure the safety of the facility during the fault. To ensure safety during an fault occurs, it is sufficient even by one line. But, In the protection wire of facilities planning it is necessary to design taking into account the potential utility.

• 대한기계학회논문집A
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• 제35권7호
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• pp.827-833
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• 2011

본 논문에서는 상용 유한 요소 해석 프로그램인 SAMCEF 를 이용하여 고속 철도 차량의 집전성능을 예측할 수 있는 해석 모델을 개발하였다. 3 자유도 스프링-댐퍼-질량의 판토그래프 모델을 생성하였고, 실제 시스템과의 리셉턴스를 비교함으로써 신뢰성을 검증하였다. UIC 799 OR 기준에서 제시한 가선계의 이론적 파동전파 속도와 가선계 유한 요소 해석 모델에서 측정한 파동 전파 속도를 비교 하였다. 드로퍼의 길이를 조절하여 전차선의 중력에 의한 초기 처짐 현상을 구현하였다. 가선계와 판토그래프를 접촉 요소를 이용하여 연성하였으며, 판토그래프가 300 km/h 및 370 km/h 로 주행할 때의 접촉력 변화를 도출하였다. 접촉력의 평균, 표준편차, 최대 및 최소값 등을 분석함으로써 본 논문에서 제시한 해석모델의 유효성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.411-413
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• 2006

This paper presents a novel fault location scheme on Korean AC electric railway systems. On AC railway system, because there is a long distance, 40 km or longer, between two railway substations, a fault location technique is very important. Since the fault current flows through the catenary system, the catenary system must be modeled exactly to analyze fault current magnitude and fault location. In this paper, before suggestion for the novel scheme of fault location, a 9-conductor modeling technique that includes boost wires and impedance bonds is introduced, based on the characteristics of Korean AC electric railway. After obtaining a 9-conductor modeling, the railway system is constructed for computer simulation by using PSCAD/EMTDC. By case studies, we can verify superiority of a new fault location scheme and suggest a powerful model for fault analysis on electric railway systems.

• 한국철도학회논문집
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• 제9권6호
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• pp.701-704
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• 2006

The catenaries must guarantee the constant electricity to the trains, so that the safety and the estimate of fatigue degree and the inspection of abrasion degree should be done rapidly. This thesis proposes the system that can manage the performance/failure of the catenaries using the image process as the solution for the weak points of the existing inspection such as the decrease of immediateness and the lack of constancy in the human resources. This study simulates the ALD using VHSV (Virture HSV) which is the unreal HSV images, not getting the real HSV in ages to the image processing technique that repeats the erosion and the expansion of the images as the methods that can monitor the slight/critical defects of the catenaries as dealing with the result of the catenaries inspection images. The final ALD (Abnormal Line Detection) system is designed based on this simulation. I have demonstrated it with the VHSV (Virture HSV) virtual images as the materials of the test and inspected it through testing the defects of the catenaries for the thesis.