• 한국정보전자통신기술학회논문지
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• 제9권2호
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• pp.243-247
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• 2016

본 논문은 급가속, 급 감속, 급제동, 급출발, 그리고 과속 등과 같은 여러 운행 이벤트 데이터는 운전자의 운행습관과 운전자의 사고위험성을 예측 또는 분석하는데 중요한 정보를 제공한다. 일반적인 자료의 분포는 정규분포, 로그정규분포, 감마분포 등을 이용하지만 운전자 운행습관을 나타내는 자료에서 사고위험성을 추정 할 수 있는 극단적인 부분에서는 언급한 분포로 적합하지 않은 경우가 발생한다. 특히 왜도가 발생하여 정규분포에 적합하지 않은 영역이 생겨난다. 본 논문에서는 이 영역에서 적합한 분포 함수와 사고를 유발하는 위험군을 분리 할 수 있고 운전자 운행 시 사전경고로 사고율을 줄 일수 있는 임계점을 분포함수의 quantile값과 군집분석 결과와 비교하여 제시하였다.

• Tribology and Lubricants
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• 제24권4호
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• pp.163-169
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• 2008

Tribological properties of ceramic brake discs were investigated using a commercial friction material. The discs were manufactured by liquid silicon infiltration (LSI) into a C-C preform. The disc surface was modified by two different methods, producing sliding surfaces with chopped carbon fibers and carbon felt. In addition, the composition of the surface was also changed. Friction characteristics of the discs were examined using a 1/5 scale dynamometer. Results showed that the type and composition of the disc surface significantly affected the level of braking effectiveness and high temperature brake performance. The discs with felt surfaces showed higher friction levels than those with chopped fiber surfaces and SiC tended to increase the friction level while C lowered the friction coefficient. The ceramic disc was more sensitive to the deceleration rate than gray iron, showing high speed sensitivity.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.174-179
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• 2007

The transient brake time or distance is one of very important factors to guess the vehicle speed to inspect an automobile accident. But, it is usual that the vehicle speed is estimated by using only skid mark without considering the transient brake distance. Deceleration and the friction coefficients of tire and road surface play an important role in calculating the brake distance. In this paper, a scheme is presented to estimate more accurate automobile speed. The scheme contains the effect of the transient brake distance on the speed. Experiment was carried out on the asphalt, unpacked road to get relationships between the speeds and the skid mark distances, and to get the transient brake time. The experimental results were utilized to construct the equation to approximate more realistic vehicle speeds.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.38-46
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• 2012

This paper discusses the energy consumption for a mid-size electric vehicle(EV) under various conditions. In order to analyze which driving style is more efficient in terms of the system of the EV, we develop the electric vehicle model and apply several types of speed profiles such as different steady speeds, acceleration/deceleration, and a real world driving cycle including the elevation profile obtained from a GPS device. The results show that the energy consumption of the EV is affected by the operating efficiency of components when driving at low speed, while it depends on required power at wheels when driving at high speed. Also this paper investigates the effect of the elevation of a road and the rate of electrical braking on the energy consumption as well as the fuel economy of a conventional vehicle model under the same conditions.

• 전기학회논문지
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• 제68권1호
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• pp.44-51
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• 2019

Tunnel Boring Machine's Technology has depends mostly on imports, currently domestic technology development was proceeding. There are many technologies in this field, above all, the large-capacity motor drive technology required for excavation is one of the core technologies. In particular, when several large motors are simultaneously starting, there are many problems due to a large starting current at that time, and it is difficult to design and operate a power receiving facility. In this paper, A method of reducing the starting current by using the regenerative power generated by the deceleration of the motor has been studied. To verify this proposal, we designed the induction motor controller using CAE based power simulation tool and verified the results of the proposed method by applying the reduced model. As a result, it is possible to reduce the maximum starting current and shorten the start-up time. Moreover, even if several motors are connected to one bank, it is proved that the method can be efficiently operated by using the sequential braking / starting sequence. In the case of a power system in which a large capacity electric motor such as a tunnel excavation system is driven, the results of this study are expected to be a stable and effective method for solving the start-up current problem and designing the power receiving facility.

• 대한교통학회지
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• 제31권1호
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• pp.3-13
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• 2013

본 연구는 신호기 위치 조정이 도시지역의 교차로 신호등에 접근하는 운전자들의 운전행태에 미치는 영향을 분석하여 딜레마 존의 특성을 분석하였다. 접근속도의 분석은 신호등의 위치 조정이 이루어진 3개 지점에서 측정된 사전-사후 비교를 통해 이루어졌다. 본 연구에서는 황색신호시 정지차량의 경우 지점속도를 낮춰, 딜레마존 시작점을 앞당김으로써 딜레마존의 크기를 작게 하는 반면에 통과차량의 경우 교차로에 근접하여 지점속도를 높임으로써 딜레마존 끝점을 뒤로 이동시키게 됨을 발견하였다. 결국 신호기 위치조정은 딜레마존의 크기를 줄임으로써 교차로 안전성을 증진하는 데 기여한다고 볼 수 있다. 동일한 속도로 진입한 차량군의 운행특성을 볼 때, 감속을 하기 위한 감속도가 반영되어 지점별 속도가 상당히 크게 변화했는데 이것은 딜레마존에서 사용되는 접근속도의 개념에 대한 보다 엄밀한 규정이 필요하며, 일반적으로 사용되는 접근속도의 개념이 접근구간속도임을 고려할 때 딜레마존의 계산식은 접근속도 보다 지점속도를 사용하는 것이 더 정확할 수 있음을 보여준다.

• 한국철도학회논문집
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• 제15권1호
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• pp.37-41
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• 2012

경부고속철도는 운영환경(차량,구배,곡선,시설물 등)에 따라 궤도회로를 여러 개의폐색으로 분할하여 운행하는 고정폐색방식의 열차제어시스템으로 운행된다. 고정폐색방식 열차제어시스템은 선행열차의 점유폐색을 기준으로 진입/진출폐색속도, 목표거리, 감속도와 같은 운행정보를 차상열차제어장치로 전송하여 연속적으로 열차를 제어하는 방식으로, 경부고속철도 열차제어시스템은 열차가 해당 폐색의 진입/진출속도를 초과할 경우, 비상제동명령을 내려 열차의 안전한 운행을 보장한다. 본 논문에서는 안전한 운행을 위해 폐색에 할당되는 속도제어코드의 생성원리를 분석하여, 최고운행속도와 운행차량특성에 따른 속도제어코드를 도출하고, 도출된 속도제어코드에 따른 운행시격 분석을 통해 열차 운행효율을 분석하였다. 이와 같은 연구는 기존 고속철도의 증속 및 신규 고속철도 열차제어시스템 설계 자료로 활용될 수 있다.

• 전력전자학회논문지
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• 제17권2호
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• pp.166-173
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• 2012

Plug-in Hybrid Electric Vehicle is driven by the engine, the primary traction motor, and the secondary auxiliary motor generating the electric power for battery charging. Secondary auxiliary motor should be connected to the engine or separated from the engine by the clutch system. This paper presents the position controller of the BLDC motor for the clutch system of Plug-in Hybrid Electric Vehicle. The BLDC motor can be applied to the clutch system in spite of it's low accuracy of the position control due to high gear ratio between the clutch and the motor. Since the attachment and the detachment between the motor and the engine should be carried out within 0.3 seconds, the position controller with fast acceleration and deceleration is implemented. For the torque control with braking operation for the BLDC motor, the modified bipolar PWM method with low current ripple compared to the conventional unipolar PWM is presented. The position control performance of the BLDC motor for the clutch system is verified through the simulation and experiments.

• International Journal of Railway
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• 제2권3호
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• pp.124-126
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• 2009

Energy savings can be achieved with optimum energy consumptions, brake energy regeneration, efficient energy storage (onboard, line side), and primarily with light weight vehicles. Over the last few years, the rolling stock industry has experienced a marked increase in eco-awareness and needs for lower life cycle energy consumption costs. For rolling stock vehicle designers and engineers, weight has always been a critical design parameter. It is often specified directly or indirectly as contractual requirements. These requirements are usually expressed in terms of specified axle load limits, braking deceleration levels and/or demands for optimum energy consumptions. The contractual requirements for lower weights are becoming increasingly more stringent. Light weight vehicles with optimized strength to weight ratios are achievable through proven design processes. The primary driving processes consist of: $\bullet$ material selection to best contribute to the intended functionality and performance $\bullet$ design and design optimization to secure the intended functionality and performance $\bullet$ weight control processes to deliver the intended functionality and performance Aluminium has become the material of choice for modern light weight bodyshells. Steel sub-structures and in particular high strength steels are also used where high strength - high elongation characteristics out way the use of aluminium. With the improved characteristics and responses of composites against tire and smoke, small and large composite materials made components are also found in greater quantities in today's railway vehicles. Full scale hybrid composite rolling stock vehicles are being developed and tested. While an "overdesigned" bodyshell may be deemed as acceptable from a structural point of view, it can, in reality, be a weight saving missed opportunity. The conventional pass/fail structural criteria and existing passenger payload definitions promote conservative designs but they do not necessarily imply optimum lightweight designs. The weight to strength design optimization should be a fundamental design driving factor rather than a feeble post design activity. It should be more than a belated attempt to mitigate against contractual weight penalties. The weight control process must be rigorous, responsible, with achievable goals and above all must be integral to the design process. It should not be a mere tabulation of weights for the sole-purpose of predicting the axle loads and wheel balances compliance. The present paper explores and discusses the topics quoted above with a view to strengthen the recommendations and needs for the weight optimization by design approach as a pro-active design activity for the rolling stock industry at large.