• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.447-453
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• 2006

The major objective of this study is to investigate the fatigue behavior evaluation of immovability crossing for railway turnout by the field test. In railway engineering, an appliance is necessary to allow a vehicle to move from one track to another. This appliance came to be known technically as turnout. So, turnout is required very complex railway technologies such as rolling stock, track. Due to the plan under the application of high speed train, turnout are needed more stable for fatigue behaviors. It analyzed the mechanical behaviors of turnout crossing with propose its advanced technical type on the field test and fatigue evaluation for the dynamic fatigue characteristics. As a result, the advanced type crossing are obviously effective for the fatigue damage ratio and dynamic response which is non-modified type. The analytical and experimental study are carried out to investigate the passing path of contact surface and fatigue damage trend decrease dynamic stresses and deflections on advanced crossing type. And the advanced type reduce dynamic fatigue damage ratio and increase fatigue life(about each 38%)more than non-modified type. From the field test results of the servicing turnout crossing, it is evaluated that the modification of contact angle, weight, material and sectional properties is very effective for ensure against fatigue risks.

• 열처리공학회지
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• 제32권4호
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• pp.161-167
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• 2019

Impact toughness and fracture behavior were studied in five kinds of non-heat treating steels containing bainite; standard(0.25C-1.5Mn-0.5Cr-0.2Mo-0.15V), high V(0.3V), Ni(0.5Mn-2Ni), W(0.4W instead of Mo), and high C-Ni(0.35C-0.5Mn-2Ni) steels. The good hardness and impact toughness balance was exhibited in the $1100^{\circ}C$-rolled condition, while the impact toughness was deteriorated due to coarse grained microstructure in the $1200^{\circ}C$-rolled condition. The impact toughness decreased with increasing the hardness in all steels studied. The fracture behavior was also basically identical, that is, the fracture area was divided into 3 zones; shear and fibrous zone, fracture transition zone with ductile dimples and cleavage cracks, where the cracks initiate and grow to critical size, unstable cleavage fracture propagation zone. The energy absorbed for the critical crack formation through the plastic deformation inside the plastic zone in front of the notch root contributed to a mostly significant portion of the total impact energy.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.67-76
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• 2012

In this paper, collision analysis of the full rake for the Next Generation High-speed EMU is conducted using a 3D/1D hybrid model, which combines 3-dimensional (3D) front-end structure of finite element model and 1-dimensional (1D) multi-body dynamics model in order to analyze train collision with a standard 3D deformable obstacle. The crush forces, passengers' accelerations and energy absorptions of a full rake train can be easily obtained through a simulation of a 1D dynamics model composed of nonlinear springs, dampers and masses. Also the obtained simulation results are very similar to those of a 3D model if an overriding behavior does not occur during collision. The standard obstacle in TSI regulation has been changed from a rigid body to a deformable body, and therefore 3D collision simulations should be conducted because their simulation results depends on the front-end structure of a train. According to the obstacle collision analysis of this study, the obstacle collides with the driver's upper structure after overriding over the front-end module. The 3D/1D hybrid model is effective to evaluate a main energy-absorbing module that is frequently changed during design process and reduce the need time of the modeling and analysis when compared to a 3D full car body.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1370-1378
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• 2007

고속철도 교량은 고속주행 열차의 차축 주기하중 효과와 교량 고유의 동적특성에 의한 동적 증폭 효과로 인하여 구조물의 안전성에 영향을 받는다. 그리고 교량의 과도한 변형으로 인하여 차륜과 레일의 접촉력 감소, 궤도틀림 등의 윤중 변동이 일어나 열차의 주행안전성 및 승차감을 저해할 수 있다. 이러한 궤도 안전성을 확보하기 위하여 동적거동에 대한 교량상판수준의 수직가속도 제한, 차륜-레일간의 접촉과 열차주행 안전성 확보를 위한 상판 면틀림 제한, 단부 회전각 변위 제한, 차량하중에 의한 교량의 수직 처짐 제한을 반드시 만족시켜야 하며, 필수적으로 공진에 대한 검토도 이루어져야 한다. 신설되는 호남고속철도에서는 기존의 경부고속철도와 다른 콘크리트 도상을 적용하고, 궤도간격, 설계열차하중 등이 변경되어 적용되므로 새로운 동적안정성 요구조건을 적용하게 된다. 본 연구에서는 콘크리트교량에 비해 진동특성이 취약한 것으로 알려진 강합성 거더 고속철도 교량의 동적거동 분석을 수행하였다.

• 대한유전성대사질환학회지
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• 제11권1호
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• pp.88-98
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• 2011

Lesch-Nyhan syndrome is a X-linked recessive disorder caused by a deficiency of the enzyme hypoxanthine-guanidine phosphoribosyltransferase (HPRT), enzyme to recycle purines. Case history: born induced vaginal delivery at 40 weeks complicated by premature membrane ruputure, body weight 2.820 gm. He showed failure to thrive showing severe protein aversion like milk products and pink daper. Developmental delay revealing rolling over at 10.5 month, followed by regression. Seizure at 2 months, His poor oral feeding was lifelong problem. Weak crying, spastic, choreoathetoid movement. Self mutilating behavior noted and diagnosed at age 3 years. No family history of consanguinity and neurological disorders. Method: Laboratory test, physical exam, imaging study and molecular. Clinical follow up Treat ment with allopurinol. Result: uric acid 10.5 mg/dL (N 3.5-7.9), APRT 151.1uM/ min/ml pro(25.7-101), HPRT 7.6 (N 233.5-701) and c.151C>T hemizygote (p,Arg51X). Abdominal sonogram showed staghorn calculi in both kidneys, brain MRI brain atrophy. Clinical follow up showed, seizure at 2 mo, developmental delay (head control and, rolling over at at 11mo, pointing body part at 2 yr 7 mo, eye hand coordination at 2 y 11mo,creeping at 3 y 7 mo, speaking words at 6 y 6 mo ),and developmental regression at 3 yr of age. Sleeping problem including insomnia and severe constipation. Self mutilating behavior (lip bite) started at 2.5 yr, neurologic sx including intermittent upward gaze accompanied by swallowing difficulty at 3 y 7 mo grand mal seizure at 4.5 yr and spastic extremity and trunchal hypotonia and choleoathetoid movement and ataxia at 6.5 yr. Scoliosis with severe spasticity at 9 yr 9 mo. Acute life threatening episode with irregular breathing at 9 yr and 9 mo, Emaciation and nephrolithiasis and recurrent pneumonia. Died suddenly at 10 yr 3 mo. Conclusion: life long feeding problem, chronic gut motility dysfunction, sleeping difficulty and progressing neurologic deterioration and nephrolithiasis despite normal serum uric acid maintence by allopurinol treatment.

• 한국산학기술학회논문지
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• 제16권8호
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• pp.5039-5044
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• 2015

본 연구에서는 철도차량의 차축소재로 사용되는 RSA1 소재에 대한 해수 부식특성 평가를 하였다. 미국재료시험협회에서 규정한 ASTM-D1141에 해당하는 인공해수를 사용하여 3전극 셀 구조를 이용한 동전위 분극법과 임피던스 분광법을 바탕으로 산출된 부식전류밀도와 부식속도는 각각 $18.3{\mu}A/cm2$와 0.217 mm/yr이다. 이 결과에 따르면 철도차량의 일반적인 내구연한인 25년을 가정할 때 한 면에서의 차축부식량은 5mm정도로 예상된다. 패러데이법칙을 바탕으로 한 정전류 부식 가속화 시험을 통해 1,3,4년의 부식양을 인위적으로 형성하였고, 단면적 감소분을 고려하여 인장시험을 시행하였다. 탄성구간에서는 부식에 의한 기계적 특성변화가 관찰되지 않았지만 소재의 연성 값은 부식이 진행 될수록 감소되는 경향을 보였다. 본 연구 결과는 향후 해수환경에서 사용될 철도차량 설계 시 고려할 기초 부식데이타로 활용될 것으로 기대된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.350-353
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• 2009

In the present study, the effect of initial microstructure, cold reduction ratio, and annealing temperature on the spherodization rate of SK85 high carbon steel sheet was investigated. High carbon steel sheet fabricated by POSCO was soaked at $800^{\circ}C$ for 2 hr in a box furnace and then treated at $570^{\circ}C$ for 5 min in a salt bath furnace followed by water quenching to obtain a fine pearlite structure. Cold rolling was conducted on the sheets of fine pearlite by reduction ratios of 20, 30, and 40% and heat treatment for spheroidization was carried out at 600 and $720^{\circ}C$ for the various time intervals from 0.1 to 32 hrs. Area fraction of spheroidized cementite was measured with an image analyzer as a function of cold reduction ratios and duration times.

• 열처리공학회지
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• 제30권6호
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• pp.251-257
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• 2017

The effect of annealing temperature on the martensitic transformation behavior, tensile deformation chracteristics and shape recovery etc., has been studied in TiNi based shape memory ribbon fabricated by coldrolling of wire. TiNi based shape memory wire (${\phi}=500{\mu}m$) of which structure is intermetallic compound could be cold-rolled without process annealing up to the reduction rate in thickness of 50%, but a few cracks appear in cold-rolled ribbon in the reduction rate in thickness of 65%. The $B2{\rightarrow}R{\rightarrow}B19^{\prime}$ martensitic transformation or $B2{\rightarrow}B19^{\prime}$ martensitic transformation occurs in annealing conditions dissipating lattice defects introduced by coldrolling. However, in case of higher reduction rate or lower annealing temperature, martensitic transformation in cold-rolled and then annealed ribbons does not occur. The maximum shape recovery rate of cold-rolled ribbons with the reduction rate of 35 and 65% could be achieved at annealing temperatures of 250 and $350^{\circ}C$, respectively. The shape recovery rate seems to be related to the stress level of plateau region on stress-strain curve.

• 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.

• Wind and Structures
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• 제9권2호
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• pp.109-124
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• 2006

This paper describes the characteristics of the fluctuating lift forces when a circular cylinder vibrates in the cross-flow direction. The response characteristics on elastically supported the circular cylinder was first examined by a free-vibration test. Next, flow-induced vibrations obtained by the free-vibration test were reproduced by a forced-vibration test, and then the characteristics of the fluctuating lift forces, the work done by the fluctuating lift, the behavior of the rolling-up of the separated shear layers were investigated on the basis of the visualized flow patterns. The main findings were that (i) the fluctuating lift forces become considerably large than those of a stationary circular cylinder, (ii) negative pressure generates on the surface of the circular cylinder when the rolling-up of separated shear layer begins, (iii) the phase between the fluctuating lift force and the cylinder displacement changes abruptly as the reduced velocity $U_r$ increases, and (iv) whether the generating cross-flow vibration becomes divergent or convergent can be described based on the work done by the fluctuating lift force. Furthermore, it was found that the generation of cross-flow vibration can be perfectly suppressed when the small tripping rods are installed on the surface of the circular cylinder.