• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.680-689
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• 2011

A dynamic analysis procedure is developed to provide a comprehensive estimation of the dynamic response spectrum for locomotive's wheels running over a Pre-Stressed Concrete (PSC) box girder bridge on the Korea high speed railway. The wheel force spectrum with the bridge behavior are analyzed as the dynamic procedure for various running speeds (50~450km/h). The high-speed railway locomotive (KTX) is used as 38-degree of freedom system. Three displacements(vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing). For one car-body and two bogies as well as five movements except pitching rotation components for four wheel axes forces are considered in the 38-degree of freedom model. Three dimensional frame element is used to model of the PSC box girder bridges, simply supported span length of 40m. The irregulation of rail-way is derived using the exponential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic responses of bridge passing through the railway locomotive with high-speed analyzed by Newmark-${\beta}$ method and Runge-Kutta method are compared and contrasted considering the developed models of bridge, track and locomotive comprehensively. The dynamic analyses of wheel forces by Runge-Kutta method which are able to analyze the forces with high frequency running on the bridge and ground rail-way are conducted. Additionally, wheel forces spectrum and three rotational components of vehicle body for three typical running speeds is also presented.

• 한국산학기술학회논문지
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• 제11권4호
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• pp.1178-1185
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• 2010

철도차량의 고속화가 가속화되면서 화물을 운송하던 컨테이너 차량이 차륜의 파손에 의하여 탈선하는 사고가 발생하여 많은 물적 피해가 발생하고 있으며, 이러한 철도차량의 사고는 많은 인명 피해와 물적 피해를 가져오는 대형 사고로 발전할 수 있다. 따라서 이에 대한 재발 방지를 위한 차륜의 파손 해석에 대한 연구가 필요한 실정이다. 철도차량의 차륜은 기계적 하중과 열하중를 동시에 받으며, 기계적 하중으로는 철도차량의 무게에 의한 수직하중과 곡선 구간을 운행할 때 차륜과 레일의 접촉부에 수평하중이 발생하며, 철도차량의 제동시 답면제동에 의한 반복적인 열하중을 받는다. 이러한 차륜에 발생하는 기계적 하중과 열하중은 차륜의 균열과 잔류응력 등을 발생시키는 것으로 알려져 있다. 따라서, 본 연구에서는 차량 주행 시의 브레이크 이력과 하중 조건을 고려한 열 구조 연성해석을 수행하여 차륜에 부하되는 최대응력을 추정하였으며, 이 값을 파괴역학 파라미터인 응력확대계수에 적용하여 차륜의 안전성을 평가하였다.

• 대한기계학회논문집A
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• 제34권10호
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• pp.1385-1391
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• 2010

본 논문에서는 폰 카메라 응용을 위해 H 형 비틀림 스프링으로 지지된 한 쌍의 사다리꼴 셔터 블레이드를 이용하는 초소형, 저전력, 고속 전자기력 Flapping 셔터를 제안한다. 기존의 정전기력 Rolling 셔터와 Flapping 셔터는 폰 카메라 응용을 위해 큰 입력 전압이 필요하며, 기존의 전자기력 Rotating 셔터는 큰 부피로 인해 폰 카메라에 사용하기 어렵다. 본 논문에서 제안하는 전자기력 Flapping 셔터는 폰 카메라에 사용 가능한 작은 크기로 회전 구동을 위해 저강성 H 형 비틀림 스프링과 저관성 사다리꼴 블레이드로 설계하여 제작된다. 실험에서 전자기력 Flapping 셔터는 입력전류 60 mA 에서 자기장 0.15 T 와 0.30 T 에 대하여 각각 최대 오버슈트 회전각 $80.2{\pm}3.5^{\circ}$와 $90.0{\pm}1.0^{\circ}$와, 정상 상태 회전각 $48.8{\pm}1.4^{\circ}$와 $64.4{\pm}1.0^{\circ}$ 성능을 보인다. 응답 시간 성능에서는 셔터 개방의 경우, 1.0 ms/20.0 ms 의 상승/정착 시간을 보이며, 셔터 폐쇄의 경우는 1.7 ms/10.3 ms 의 하강/정착 시간을 보인다. 본 논문에서는 폰 카메라용 셔터 응용을 위해 제안하는 전자기력 Flapping 셔터의 초소형(${\sim}8{\times}8{\times}2\;mm^3$), 저전력(${\leq}60\;mA$), 고속(~1/370 s) 성능을 실험적으로 검증하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.310-313
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• 2009

오스테나이트계 고질소 스테인레스강 4 가지 후보강종인 HNS C1, C2, C3, C4에 대해 질소함량, 가압조건 따른 단조재와 온도 및 동일한 가압조건에서 Ni 합금원소 첨가유무에 따른 용체화 처리재(HNS C1, C3)의 물성평가와 실제 냉연 공정의 pass schedule 검증을 위한 모사실험을 통해 다음과 같이 요약 하였다. 1) 가압증가에 따른 질소함량의 증가로 강도 및 경도가 동시 상승하며, 결정립의 미세화 및 기계적 쌍정 발생이 많았다. 동일한 가압조건에서 Ni 첨가된 HNS C3가 Ni 미첨가한 HNS C1 보다 강도-연성 조합평가에서 열/냉간 가공성 등의 특성이 우수하였다. 2) 고질소강 스테인레스강의 적정한 용체화 처리온도 범위는 상용화된 AIS1304와 유사한 $1050^{\circ}C{\sim}1100^{\circ}C$이며, 용체화처리 후냉각방법의 변경(수냉과 공냉)에 따른 경도의 편차는 없었다. 냉연 pass schedule 검증을 위한 모사실험에서 초기 압연의 최적조건은 roll 속도 5mpm, pass당 압연율 $15{\sim}17%$였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.595-602
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• 1994

PERISTOR-3000 loaded with 32 bit DSP(Digital Signal Processor) is a technically advanced versatile dc motor controller in applications with very high requirements for rapid response, control accuracy and reliability. The current controller of PERISTOR-3000 is of the predictive type and gives fast control with both discontinuous and continuous current compared to the conventional PI current control. The speed controller gain is compensated to improve response behavior. PERISTOR-3000 communicates with its host computer, POSTAR-3200, or any IBM or compatible PC and can be controlled. Dedicated monitoring system for MMI is introduced.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.780-788
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• 2008

As a railway is receiving attention as an environment-friendly transportation mode, many high speed, inter-city and urban railway are constructed and remodeled in the world. With this trend, railway RAMS was included in the international standard IEC 62278 in 2002. RAMS activity in domestic market is also increased with this international trend. However, IEC 62278 does not describe the methodology of substantial contents like how reliability target is set although it can be used as an overall guideline when RAMS requirements are included in the purchase specification. That is because RAMS requirements should be set with the specific railway condition. It is required to fully understand the meaning of railway RAMS parameters and apply those correspond to the specific railway system and environment condition especially when a quantitative RAMS requirement is set. In this study, the meaning and characteristics of RAMS parameters applicable to the development of quantitative RAMS requirement of rolling stock is described. And the basic concept of RAMS and the definition of failure that IEC 62278 describes is modified and suggested in order to make more suitable to the development of quantitative RAMS requirement.

• 한국기계가공학회지
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• 제15권2호
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• pp.57-65
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• 2016

The suspension system of a subway vehicle is composed of $1^{st}$ and $2^{nd}$ springs. The suspension system is the most important parameter in determining the vibration ride comfort. If the $1^{st}$ suspension spring is designed as a spring with strong stiffness to improve the running stability at high speed, it causes vehicle vibrations. In this paper, by testing and analyzing changes of the characteristics of Chevron springs, which have been the primary suspension springs used for about 20 years, we study how changing the characteristics affects vehicle acceleration and ride comfort. The lateral and longitudinal vibrational ride comfort index levels were lower than the vertical ones. Therefore, as increasing the stiffness of Chevron springs has the greatest effect on the vertical vibrational ride comfort index level, a countermeasure for vertical vibration reduction is needed when the stiffness increases owing to aging. Finally, maintenance guidelines, including the replacement time for the Chevron rubber, were proposed based on these findings.

• 전기학회논문지
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• 제64권12호
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• pp.1804-1809
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• 2015

The study in railway system to apply a fuel cell system with high efficiency and mobility than other renewable energy is being actively conducted. It is needed a analysis on load characteristics and control method of rolling stock in order to apply to rolling stock. This paper presents study on control small-scale prototype power converter electric railway vehicle using fuel cell generation system. Experiment is conducted through real fuel cell generation system and reference speed applying the driving curve of the actual electric railway vehicle was applied. Also, output voltage of boost converter is controlled considering characteristic of fuel cell. And it was confirmed characteristic according to powering and regeneration of inverter.

• 한국정밀공학회지
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• 제31권9호
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• pp.783-790
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• 2014

Railway wheels and axles are the most critical parts of the railway rolling stock. The wheel carry axle loads and guide the vehicles on the track. Therefore, the contact surface of wheel are subjected to wear and fatigue process. The wheel damage can be divided into three types; wear, contact fatigue failure and thermal crack due to braking. Therefore, in the contact surface between the wheel and the rail, the materials are heat treated to have a specific hardness. The manufacturing quality of the wheel have a considerable influence on the formation of tread wear and damage. Also, the residual stress on wheel is formed during the manufacturing process is one of the main sources of the damage. In this paper, the mechanical characteristic and the residual stress according to wheel material have been evaluated by applying finite element analysis and conducting mechanical tests.

• 대한기계학회논문집A
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• 제24권7호
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• pp.1650-1660
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• 2000

Continuous casting process has been adopted increasingly in recent years to save both energy and labor. It has experienced a rapid development in the production of semi-finished steel products, rep lacing the conventional route of ingot casting and rolling. In order to achieve this merit, however, more studies about the mechanism between roll and slab are needed. In this paper, a dynamic bulging in steel cast slabs was simulated by considering the solidification and heat transfer. This study is to prevent internal cracks of a slab in a bending and unbending zone. The value of moving strand shell bulging between two supporting rollers under the ferrostatic pressure and slab-self weight has been calculated in terms of creep and elasto-plasticity. The strain and strain rate distributions in solidified shell undergoing a series of bulging are calculated with working boundary conditions.