• 한국산학기술학회논문지
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• 제16권6호
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• pp.3731-3735
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• 2015

국내 최초로 개발된 동력분산형 고속열차인 HEMU-430X의 최고속도시험 중 실시한 차량 중량과 가속성능간의 상관관계에 대해 보고한다. 차량의 출력을 일정하게 유지한 채, 차량에 중량물 설치 및 제거를 통해 전체 차량의 중량을 2% 변화시킬 때의 차량 가속성능을 분석한 결과, 시험 최고속도인 413km/h속도 영역에서는 중량이 가벼울 때 최고속도시험에 유리한 것으로 나타났다. 시험 종료 후, 시험 당시 0.1초 단위로 측정된 속도 데이터를 바탕으로 속도별 차량의 추진에 사용된 소비전력을 측정한 결과 차량의 견인력과 공기저항력이 같아져서 더 이상 추진이 되지 않는 균형속도는 419km/h로 산출이 되었으며, 이는 중량이 가벼울 때 가속이 유리하다는 시험 결과와 일치한다. 이러한 분석 결과를 바탕으로 향후 HEMU-430X의 증속 시험에 활용할 계획이다.

• 산업경영시스템학회지
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• 제46권4호
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• pp.312-320
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• 2023

Recently, there has been an increasing attempt to replace defect detection inspections in the manufacturing industry using deep learning techniques. However, obtaining substantial high-quality labeled data to enhance the performance of deep learning models entails economic and temporal constraints. As a solution for this problem, semi-supervised learning, using a limited amount of labeled data, has been gaining traction. This study assesses the effectiveness of semi-supervised learning in the defect detection process of manufacturing using the MixMatch algorithm. The MixMatch algorithm incorporates three dominant paradigms in the semi-supervised field: Consistency regularization, Entropy minimization, and Generic regularization. The performance of semi-supervised learning based on the MixMatch algorithm was compared with that of supervised learning using defect image data from the metal casting process. For the experiments, the ratio of labeled data was adjusted to 5%, 10%, 25%, and 50% of the total data. At a labeled data ratio of 5%, semi-supervised learning achieved a classification accuracy of 90.19%, outperforming supervised learning by approximately 22%p. At a 10% ratio, it surpassed supervised learning by around 8%p, achieving a 92.89% accuracy. These results demonstrate that semi-supervised learning can achieve significant outcomes even with a very limited amount of labeled data, suggesting its invaluable application in real-world research and industrial settings where labeled data is limited.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.761-767
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• 2011

Since the "Low Carbon, Green Growth" as a social requirements is attracted public attention, the policies and investments of the railway which have been less estimated than road is re-considered. Since the starting the commercial service (2004. April), the KTX have been operated successfully while transport passengers over 100million for years. And also the project for development of KHST (Korea High Speed Train ; G7) had been accomplished with a good result, the first trainset of KTX-II which base on G7 project was manufactured and testing now. On the other hand, the world's technology of the high speed train is more faster, and changing to a distributed traction system. To catch up the world's leading technology, the HEMU(High-speed Electric Multiple Unit) project will secure new technology and aims to promote the technology of domestic high-speed train. The authors indicates the result of detail review such as a curve, slope of the track and electrical dead section of the catenary to test at 400kph and also the performance simulation of the developed rolling stock in this paper. As the result, the authors devise the test scenario to perform a maximum speed test (stability at max. speed, acceleration & deceleration etc) with the restricted conditions such as track length, track available time etc by considering above result.

• 제어로봇시스템학회논문지
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• 제21권2호
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• pp.137-144
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• 2015

In hybrid or electric vehicles, the hydraulic brake system must be controlled cooperatively with the traction motor for regenerative braking. Recently, a motor driven brake system with a PMSM (Permanent Magnet Synchronous Motor) has replaced conventional vacuum boosters to increase regenerative power. Unlike industry motor controls, additional source codes such as functional safety are essential in automotive applications to meet ISO26262 standards. Therefore, the control logic execution time increases, which also causes an extension of the motor current control period. The increased current control period makes precise motor current control challenging inhigh speed ranges where the motor is driven by high frequency. In this paper, a PWM update strategy and a time delay compensation method are suggested to improve current control and system performance. The proposed methods are experimentally verified.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.14-19
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• 2012

On-line and real-time information of the longitudinal velocity is the essential factor for the Advanced Vehicle Control Systems such as ABS(Anti-lock Brake System), TCS(Traction Control System), ESC (Electronic Stability Control) etc. However, the longitudinal velocity cannot be easily measured or calculated during braking maneuvering. A new algorithm is presented for the estimation of the longitudinal velocity with the measurements of the vehicle longitudinal/lateral acceleration, steering angle and yaw rate. The algorithm is designed utilizing the Extended Kalman Filter based on the 3 degree of freedom vehicle model. In order to compensate for the biased sensor signal on the inclined road, the inclined angle is also estimated. The performance of the proposed estimation algorithm is evaluated in field tests.

• 전기학회논문지
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• 제63권7호
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• pp.1013-1018
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• 2014

This paper described the development of equalizing spacer for minimization of voltage drop according to DC feeder extension. Power consumption is increased as shorter interval of train driving time and transportation capacity increase in urban subway. Therefore we investigated voltage drop of catenary at a point in case of traction driving of a train in parallel to the DC power supply system. Based on it's result, equalizing spacer is designed and fabrication to minimize the voltage drop in accordance with the power supply line arranged in three rows, and then its performance was confirmed that the stress distribution of main body and the distributed load are satisfied through the body structure modeling.

• 한국군사과학기술학회지
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• 제14권5호
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• pp.747-752
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• 2011

Recently, skid steering methods have been increasingly applied to unmanned ground vehicles since they can provide a narrow turn that general steering methods like ackerman steering may not provide. However, dynamic behaviors of the skid steering vehicles with articulating arms which occur during a steering are very complicated and coupled. This makes it difficult to control vehicles and in severe case vehicles may loose stability. There are two methods to control unmanned ground vehicles. The first one is speed control method generally used with easiness and robustness in remote vehicle control. The next one is torque control allowing the vehicles to get better performance in several cases provided careful application is achieved. This paper addresses dynamic phenomena of skid steering vehicles during steering and compares with vehicle driving control methods between torque(traction force) control and speed control.

• 한국군사과학기술학회지
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• 제19권4호
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• pp.517-525
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• 2016

In this research, the effect of the pressure control of cooperative control system with regenerative brake for a military series hybrid-electric vehicle was studied. A cooperative control system with regenerative brake was developed to maximize regenerative energy from electric traction motors of the vehicle. However, the pressure control method of the system was modified to solve a time delay problem and it deteriorates the performance of the system. A Simulink model including the hybrid-electric components, the cooperative control system with regenerative brake, and the vehicle dynamics was developed and used to find a solution. The regenerative energy ratio with respect to the whole brake energy was increased in this research from less than 60 % to over 80 %.

• 전기학회논문지
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• 제63권3호
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• pp.431-436
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• 2014

In this paper, temperature change properties on the 210kW-class Interior Permanent Magnet Synchronous Motor (IPMSM) are performed with the cooling performance of a water cooling device through the thermal characteristic analysis of the IPMSM considering a real driving pattern of urban railway vehicles. First, the thermal analysis modeling of 210kW-class IPMSM, which is an alternative to the conventional induction motor, and its water cooling device is conducted. Next, the thermal characteristic analysis of the IPMSM considering a real driving pattern of urban railway vehicles is performed using 2-Dimensional FEM tool. Finally, the calculated characteristic results are analyzed. Consequently, it is confirmed that the internal temperature of the 210kW-class IPMSM may be lowered to about 42~52% by maintaining the coolant flow rate of the water cooling device (Cross sectional shape of the pipe has 220mm width and 10mm height) for 0.2kg/s level.

• Structural Engineering and Mechanics
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• 제66권6호
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• pp.749-759
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• 2018

Aiming at widely used high-pier bridges in Sichuan-Tibet Railway, this paper presents an investigation to design and evaluate the seismic vibration reduction effects of several measures, including viscous damper (VD), friction pendulum bearing (FPB), and tuned mass damper (TMD). Primarily, according to the detailed introduction of the concerned bridge structure, dynamic models of high-pier bridges with different seismic vibration reduction (SVR) measures are established. Further, the designs for these SVR measures are performed, and the optimal parameters of these measures are investigated. On this basis, the vibration reduction effects of these measures are analyzed and assessed subject to actual earthquake excitations in Wenchuan Earthquake (M=8.0), and the most appropriate SVR measure for high-pier bridges in Sichuan-Tibet Railway is determined at the end of the work. Results show that the height of pier does not obviously affect the performances of the concerned SVR measures. Comprehensively considering the vibration absorption performance, installation and maintenance of all the employed measures in this paper, TMD is the best one to absorb vibrations induced by earthquakes.