• 한국산학기술학회논문지
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• 제22권3호
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• pp.199-207
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• 2021

본 연구는 한국형고속철도(KTX)의 제동장치의 국산화를 통한 성능 개선을 위한 목적으로 수행되었다. 본 연구에서 기존 수입에 의존하고 있는 고속철도용 제동 디스크 허브를 국산화하기 위하여 유한요소 해석을 통해 성능을 분석하고 제동 시험결과와 상관도 분석을 통해 모델의 검증을 수행하였다. 또한, 제동시 발생할 수 있는 기계적인 특성을 검토하기 위하여 마찰열에 의한 열전달-열응력 해석, 고유진동해석 및 강도해석을 수행하였다. 디스크 허브 국산화 신규 모델의 개발을 위해 형상에 따른 설계 인자를 도출하고 파라미터 해석을 수행하여 방열성능을 향상시키고 경량화를 위한 최적 사양을 도출하고자 하였다. 개발 모델을 기존 모델과 비교한 결과 기존 모델 대비 제동시 발생하는 허브의 최고 온도가 낮아졌으며, 냉각 효율이 향상되었음 확인할 수 있었다. 또한, 고유진동수 및 강도 특성 또한 동등 수준 이상의 성능을 확보한 설계임을 확인하였다. 본 연구 결과는 철도차량 및 수송기기 분야의 제동 디스크 시스템 개발에 활용될 수 있을 것으로 기대된다.

• 자동차안전학회지
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• 제9권1호
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• pp.19-24
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• 2017

This paper present a performance evaluation scenarios to assess the safety performance of autonomous emergency braking (AEB) system for cyclist collision. To guarantee the safety performance of AEB for cyclist, AEB system should be tested in various scenarios which can be occurred in real driving condition. For this, real-traffic car-to-cyclist collision data are analyzed to classify the real traffic collision scenarios. Using this information, typical car-to-cyclist collision scenarios are selected. Also, in order to develop the detail features of these collision scenarios, several accident cases related with these scenarios are explained. Based on these information, test scenarios which can describe the car-to-cyclist collisions occurred in Korea are proposed. For practicality and feasibility of the test scenarios, proposed scenarios should be designed to assess the safety performance of AEB system effectively. For this, some test scenarios are combined or removed based on the consideration about the effectiveness of each scenario to the assessment of the performance of AEB system. To confirm that the proposed test scenarios are realistic and physically meaningful, simulation is conducted using simple AEB system in proposed test scenarios.

• 동력기계공학회지
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• 제8권4호
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• pp.57-63
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• 2004

Conventionally, 2WS is used for vehicle steering, which can only steering front wheel. In case of trying to high speed lane change or cornering through this kind of vehicle equipped 2WS, it may occur much of Yaw moment. On the other hand, 4WS makes decreasing of Yawing Moment, outstandingly, so it is possible to support vehicle movement stable. And conventional ABS and TCS can only possible to control the longitudinal movement of braking equipment and drive which can only available to control of longitudinal direction. There after new braking system ESP was developed, which controls both of longitudinal and lateral, with adding of the function of controlling Active Yaw Moment. On this paper, we show about not only designing of improved braking and steering system through establishing of the integrated control system design of 4WS and ESP but also designing of the system contribute to precautious for advanced vehicle stability problem.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.541-549
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• 2018

본 연구에서는 국내 화물 및 여객차량들을 견인하는 디젤전기 기관차의 제동에 따른 동적 거동을 분석하기 위하여 제동장치에 영향을 미치는 마찰계수, 제동압력, 주행저항 등을 시험하였다. 마찰계수는 UIC 541-4를 참고로 Dynamo 시험을 수행하였으며 시험결과는 다변량 회귀분석을 통해 제동하중, 제동초기 속도와의 관계를 분석하여 제시하였다. 제동압력은 상용제동과 비상제동으로 구분하였으며, 제동밸브와 배관의 특성을 반영하기 위하여 시간에 따른 제동압력 변화를 대상 차량에서 측정하였다. 차량에 작용하는 외력을 반영하기 위하여 EN 14067-4의 타행시험을 수행하고 2차 다항식 형태의 주행저항을 제시하였다. 도출한 주행저항을 동일 차종에 대하여 각 국가별로 사용하고 있는 주행저항들과 비교하였다. 차량의 재원, 마찰계수, 제동압력, 주행저항을 바탕으로 직선 평탄 선로를 주행하는 디젤전기기관차의 동적 거동을 EN 14531-1에서 제시된 시간적분을 이용하여 해석하였다. 해석 결과는 상용제동과 비상제동에 대하여 각각 차량의 속도이력 시험결과와 비교 검증하였으며 상당히 합리적인 결과를 도출하였다. 본 연구의 결과들은 철도차량들을 연결하여 운행하는 열차의 동적 거동해석에 활용할 수 있을 뿐 아니라 차량 설계에서 제동에 영향을 미치는 다양한 파라미터들을 분석하고 성능향상의 기초자료로 활용할 수 있을 것으로 기대된다.

• 센서학회지
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• 제16권1호
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• pp.68-76
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• 2007

In general, the braking system of a high speed train has an important role for the safety of the train. To stop safely the train at its pre-decided position, it is necessary to properly combine the various brakes. The train has adopted a combined electrical and mechanical (friction) braking systems. In order to design a good brake system, it is essential for designers to predict the brake performance. In this paper, the braking performance analysis program has been developed and verified by comparing the simulation results with the brake test results of HSR-350x; both results match very well. Also, the brake performances of high speed trains can be predicted by using this program under various conditions.

• International Journal of Automotive Technology
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• 제8권2호
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• pp.249-258
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• 2007

This paper proposes a method that can be used for the resistance estimation of a PWM (Pulse Width Modulation)-driven solenoid. By using estimated solenoid resistance, the PWM duty ratio was compensated to be proportional to the solenoid current. The proposed method was developed for use with EHB (Electro-Hydraulic Braking) systems, which are essential features of the regenerative braking system of many electric vehicles. Because the HU (Hydraulic Unit) of most EHB systems performs not only ABS/TCS/ESP (Electronic Stability Program) functions but also service braking function, the possible duration of continuous solenoid driving is so long that the generated heat can drastically change the level of solenoid resistance. The current model of the PWM-driven solenoid is further developed in this paper; from this a new resistance equation is derived. This resistance equation is solved by using an iterative method known as the FPT (fixed point theorem). Furthermore, by taking the average of the resistance estimates, it was possible to successfully eliminate the effect of measurement noise factors. Simulation results showed that the proposed method contained a sufficient pass-band in the frequency response. Experimental results also showed that adaptive solenoid driving which incorporates resistance estimations is able to maintain a linear relationship between the PWM duty ratio and the solenoid current in spite of a wide variety of ambient temperatures and continuous driving.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.238-241
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• 2008

A brake system in automobile is one of the important parts that directly affect the safety of passengers. Particularly, disk brake module is applied to almost all kinds of automobile brake system due to its remarkable braking power and braking distance. In the disk brake module of an automobile, the bolt for tire wheel is assembled to the disk brake hub by interference fit (bolt pressing process). The process induces small deformation whose range is within tens of ${\mu}m$ and this deformation may cause the runout badness of the whole disk brake module, and even braking problems such as judder or squeal phenomena which makes the loss of braking efficiency. In this study, bolt pressing fit into hub was simulated by $ANSYS^{TM}$, a commercial structure analysis program. Also, the aspect and the cause of hub displacement were analyzed and the solution for decreasing runout of hub was proposed.

• 자동차안전학회지
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• 제14권3호
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• pp.41-47
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• 2022

Composite material is recently very important material for eco-friendly vehicles because of its excellent mechanical property and lightweight effect. So, many research results have been recently published for developing the composite material to apply vehicles. In this paper, new brake system is presented using composite material to response this situation. And advantages in terms of performance compared to competitive company will be discussed in depth to verify superiorities of the new composite brake. To do so, composite brake systems which have the same size as the competitive company to the same vehicle is applied. And superiorities through a variety of test results are presented. First, normal braking performances are compared with competitive company through braking effect, heat capacity and friction test, Second, circuit driving and high speed fade test are also verified with competitive company to confirm harsh braking performances for the new composite brake system. Finally, the effects of applying the composite brake to automobile industry like electric car are analyzed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.280-281
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• 2011

Special Protection Scheme(SPS) that operates scenarios about faults beyond the normally protective action is wide system protection technology for the purpose of wide areas protection. Therefore, the SPS focuses on the improvement of the power supply capability by protecting the system rather than protecting the system equipments. Since the SPS requires emergency operation, the operation schedule is set up in advance by analyzing various scenarios. Since the SPS's action scheme uses generator tripping and is a classical method it is presently the most powerful one. However, as the setting of SPS is set to the most severe disturbance, the scheme tends to trip more generators than required to prevent fault propagation. It is highly likely that tripping generator units to prevent fault propagation would result in difficulty of system management and possibility of load shedding. Accordingly, it is desirable that generators are connected to the system within the range that ensures system stability and intelligent SPS is currently under development to solve the problem being stated. In this paper, as a part of developing the intelligent SPS, application of the fast-valving and braking resistor scheme to the generators is being proposed and analysed to reduce the number of tripped generators.

• Tribology and Lubricants
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• 제22권3호
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• pp.149-154
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• 2006

This paper presents the braking friction and wears on the rubbing surfaces of a friction pad-disk brake. In this study, four friction disk specimens are sampled from unused and used disks in which are taken from the disk brake system when the friction induced vibration and noise problems have been occurred during a braking period at a running period of 10,000 km, 20,000 km, and 30,000 km in random. The experimental results indicate that the tribological characteristics of an unused disk brake shows equal and stable as a friction coefficient and temperature distributions during a braking friction/wear test period including a total friction mode from the start to running periods. But the used disk brake shows unstable and uneven friction modes between an outside and inside rubbing surfaces of a disk brake in terms of a friction coefficient and wears. This may lead to a friction induced friction vibration and noise problems of a used disk brake.