• 한국철도학회논문집
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• 제14권3호
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• pp.203-210
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• 2011

본 논문에서는 열차 충돌로 발생되는 충격으로 차축에 큰 수직하중 및 수평하중이 부과될 때 플랜지가 레일을 타고 오르는 탈선현상을 예측할 수 있는 단일 윤축의 이론적 탈선 모델을 연구하였다. 철도차량 충돌 시 크게 타고오름(wheel-climbing), 들려오름(lift-up), 전복(roll-over) 등과 이들의 복합유형탈선이 발생할 수 있다. 타고오름 및 복합 유형의 탈선은 세 가지(Climb-over, Climb/roll-over, Roll-over)로 정의할 수 있다. 본 논문에서는 충돌 후 탈선거동을 예측하기 위하여 타고오름 및 복합 유형 탈선에 대한 단일윤축 이론모델을 제안하고, 정의한 세 가지 탈선거동이 발생하기 위한 조건을 제시하였다. 타고오름 및 복합 유형의 탈선거동을 예측하기 위하여 제안된 단일윤축 이론모델의 타당성을 단순플랜지 형상 윤축모델을 사용한 동역학 시뮬레이션을 통하여 검증하고, 타당성을 보인다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1144-1148
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• 1991

The problems occurred when developing a automatic wheel deburring system are to make effective flexibility in model change and the irregularity of the position/shape of the burr, to select optimal robotic manufacturing process and to develope optimal end effector. The locations where burr exists are on flange, rim and spoke. Here will be discussed the optimal solution for the removal of rim burr by using robot. The research can be summarized as the automatic robot path generation by recognizing rim contour and automatic deburring process technique. Various rim contour data is generated automatically when the sensor which is fixed to robot is moving with the parallel motion to the wheel center axis and this generated data is transferred to the data storage system and converted to the robot path data. The robotic tool system which is suitable to the rim deburring process is developed by integrating tool, compliance function and sensor. And factory automation system controlled by robot controller and PC is developed. This system shows good productivity and flexibility.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.179-186
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• 2001

As the freight traffic becomes heavier, the high speed of existing freight cars is essential instead of the construction of a new railway. The high speed can be achieved by the design modifications of the freight bogie. In this paper, an analytical model of freight bogie including the lateral force between rail and the flange of wheel is developed to decide the critical speed, which activates a hunting motion and tells the running safety of freight bogie. The dynamic responses of the analytical model were compared with an experimental data from a running test of a freight bogie and showed good agreements between them. The analytical model is used to find the design modifications of the freight bogie by parameter studies. The results show that the reduction of wheelset mass ratio and the increase of the axle distance of the freight bogie can increase the critical speed, but the primary lateral stiffness has little effects on the critical speed. And this also study shows that smaller wheel conicity deteriorates the running safety of the freight car, which means the overhauling of the wheel of freight bogie should be done regularly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.1093-1098
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• 2002

Dynamic behaviors of the Korean High-speed Train(KHST) have been analyzed to investigate the performance on the stability, the safety and the ride comfort. Multi-body dynamics analysis program using Recursive method, called RecurDyn, have been employed in the numerical simulation. To model the wheel-rail contact, the RecurDyn uses its built-in module which uses the square root creep law. The accuracy of the rail module in RecurDyn. however, decreases in the analysis of flange contact because it linearizes the shape of the wheel and rail. To solve this problem, a nonlinear contact theory have been developed that considers the profiles of the wheel and rail. The results show that the KHST still needs more stability. The problem should be solved by the examinations of module and modeling.

• 한국철도학회논문집
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• 제19권5호
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• pp.565-575
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• 2016

철도차량 영업 운행 중 빈번히 발생하는 차륜 마모, 손상 등의 결함을 제거하기 위하여 실시되는 차륜 전삭 공정과 관련하여 전삭 전후의 차량 동적성능을 분석하였다. 전동차를 대상으로 차륜 전삭 전후의 차륜답면형상을 계측, 분석하였으며 진동 및 승차감 특성을 분석하고자 차량 주행시험을 실시하였다. 시험결과, 차륜 전삭 후 차량 진동 RMS값은 전삭 전에 비하여 저감되었으며 철도차량 기술기준에 의거 분석한 차체 진동성능은 전삭 전에 비하여 개선되었다. 승차감레벨은 전삭 전에 비하여 전삭 후 좌우, 상하방향 모두 최대 약 3dB의 개선 효과를 보였으며 주행안전성 또한 개선됨을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.174-177
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• 2007

In this paper the noise characteristics of metro train is investigated experimentally. It is primarily aimed at observing the squealing noise radiation of each wheel when the vehicle pass the curve sections. This will be used to understand the noise excitation mechanism at the contact area between squealing wheels and rails which induce squeal noise at curve sections. To identify the related key parameters and boundary conditions on-board monitorings of the noise, vibration of the wheel and bogie and displacement behaviour of the wheels and rails have been done. In this paper only noise measurement and results are discussed. From spectrogramms squeal noise due to creepage and noise due to flange contact of the wheels could be identified. At the moment of the curve passing the highest squeal levels are found on the front inner wheel. However since curve noise depends on variable factors more analyses will be followed to identify the squealing wheels and the noise excitation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.434-437
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• 2006

Due to the shape of spindle with small diameter and heavy section, rapid cooling is difficult. It is difficult to fabricate the tapered wheel bearings with fine microstructure. Thus, their mechanical characteristics, such as yield strength and fatigue resistance, decrease. Producing the tapered wheel bearings with good workability during orbital forming after hot forging, hot forging process with several process parameters was optimized by means of statistical technique of Six-Sigma scheme. As a result, the lower heating temperature is, the lower the hardness and yield strength of forgings are. Also, the faster conveyer velocity is, the lower the hardness and yield strength of forgings are. To avoid therefore occurrence of the surface rupture during orbital forming, the heating temperature should be controlled as low as possible and the conveyer velocity should be controlled as fast as possible.

• Design & Manufacturing
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• 제15권1호
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• pp.14-20
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• 2021

The objective of this study is to introduce the new possibility of sensing technology based on inductive displacement sensors to monitor the status of wheel position in the hot forging process. In order to validate effectiveness of proposed sensing technology, the indirect forging force measurement with displacement sensor was applied into a typical closed hot forging die-set used for the manufacturing of flange bolts. The locations to implement the displacement sensor were selected carefully by simulating forming process and static structural. From the measurement results of the forging force change during one hot forging cycle, it was found that the proposed monitoring system can provide useful information to understand the detailed behaviors of die-set in the closed hot forging process.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.4963-4967
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• 2012

본 연구에서는 마그네슘 합금 AZ91D를 소재로 18인치 휠을 개발하고 동일사양의 알루미늄 휠과 해외 시판중인 마그네슘 휠과 기계적인 성질을 비교하였다. 저압주조 방식에 의해 18인치 마그네슘 휠 시제품을 제작하여 동일 사양의 알루미늄 휠 대비 26% 의 경량화를 이룩하였고, 신판 마그네슘 휠 대비 동등 수준의 연신율, 인장강도, 경도를 달성하였다. 향 후 주조와 열처리 공정 개선을 통해 항복강도 향상이 필요한 것으로 판단된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.143-150
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• 2000

Like conventional railways, improving running performance of vehicle in curve is more effective than improving maximum speed to reduce traveling time. But some vehicles have problems concerning running performance in cure because of insufficient study for our conventional railway characteristics. So, these problems brought about increasement of maintenance cost. This study was started to deliberate several plans to solve problems concerning running performance in curve. Some modifications of primary suspension and tests were carried out to improve curve negotiation. Here, we describe some results.