• 한국기계가공학회지
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• 제11권2호
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• pp.47-54
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• 2012

An oxygen sensor installed in vehicle exhaust systems enables to measure the amount of oxygen in the exhaust gas, in which the measured data are collected and analyzed in ECU(Engine Control Unit). The oxygen sensor is exposed to the high speed exhaust gas at high temperature circumstance, so that protection caps are required not only to protect the susceptible measuring part, but also to provide the real time measurement without time delay. In this study, a new oxygen sensor with one protection cap was proposed, and the CFD analysis was carried out in order to compare the performance characteristics, such as flow speed and ratio of AOA(Age of Air), for the conventional and new oxygen sensor. The numerical results of CFD analysis provided the flow speed of 1.34m/s and the ratio of AOA of 3.43. The similar features obtained from the numerical results showed that the new oxygen sensor guarantees the same performance characteristics of the conventional ones.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.529-538
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• 2009

A trial run of locally-developed tilting train has been in process on Chungbuk line since the test vehicle was first produced. For the system stabilization, interface verification among the systems including track, structure, catenary and signaling system, not to mention the rolling stock, is very crucial. Therefore, in this study, the dynamic rail force of the tilting (Hanvit 200), high-speed (KTX) and general (Mugunghwa) vehicle caused by driving in transition curve track was measured. And, it compared the tilting response with the other by using the measured wheel load data in transition curve track, and then evaluated probability the range of wheel load fluctuation for the variable dynamic vertical and lateral wheel load. As a result, a range of wheel load by occured a change of cant from the high-speed and general vehicle which had fixed bogie structure was distributed throughout small deviation (${\Delta}8{\sim}13kN$). Otherwise, in case of the tilting train which was consisted of the pendulum bogie structure was distributed wide range about large deviation (${\Delta}25{\sim}28kN$) by changed of cant.

• 드라이브 ㆍ 컨트롤
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• 제19권3호
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• pp.32-38
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• 2022

The in-wheel drive gearbox for military special vehicles converts the high-speed & low-torque output generated by the electric servomotor, into low-speed & high-torque mechanical power. As the vehicle is remotely maneuvered in mountainous terrain, wet fields, rough terrain, etc., the gearbox must generate a maximum input speed exceeding 5,000 rpm, a maximum torque of 245 Nm, and MTBF of 9,600 km. The purpose of this study was to analyze the failure mode of the gearbox, to ensure the durability of the in-wheel drive gearbox. Also, the field load test data of the vehicle was analyzed, the acceleration durability test standards were established, the acceleration durability test was conducted, and the durability test results were analyzed as well.

• 한국철도학회논문집
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• 제8권4호
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• pp.348-353
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• 2005

In designing the structures of railway rolling stocks, deterministic methods associated with the concept of a safety factor have been traditionally used. The deterministic approaches based on the mean values of applied loads and material properties have been used as safety verification for the design of rolling-stock car body structures. The uncertainties in the applied loading for the high speed train and the strength of new materials in the rolling stocks require the application of probabilistic approaches to ensure fatigue safety in the desired system. Pressure loadings acting on the car body when the train passes through tunnels show reflected pressure waves for high-speed trains and they may cause a fatigue failure in vehicle bodies. Use of new material technology as body structures also introduces uncertainties in the material strength. A probabilistic approach is more adaptable in designing reliable structures when the pressure waves from the tunnels pounds and new material technology is adopted. In this paper, it is proposed that a fatigue design and assessment method based on a reliability which deals with the loading variations on a railway vehicle due to the pressure reflected in tunnels and the strength variations of material. Equation for the fatigue reliability index has been formulated to calculate the reliability assessment of a vehicle body under fluctuating pressure loadings in a tunnel. Considered in this formulation are the pressure distribution characteristics, the fatigue strength distribution characteristics, and the concept of stress-transfer functions due to the pressure loading.

• 한국철도학회논문집
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• 제16권1호
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• pp.26-31
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• 2013

감속구동장치는 모터에 회전력을 차륜에 전달하는 중요한 장치로써 가장 큰 고장원인 중 하나는 기어의 접촉 피로손상에 의한 것이다. 이로 인해 주행 시 심각한 영향을 미칠 수 있기 때문에 주행안전성 확보를 위한 이상진단 모니터링시스템 기술이 요구되고 있으며, 이상진단을 위한 모니터링 시스템 개발을 위해 고장이 없는 감속구동장치의 기초 데이터 분석이 중요하다. 기어의 주요 이상진단방법 중 고장원인파악 및 조기진단에 주로 사용되는 진동신호분석법을 적용하여, 본 논문에서는 고장이 없는 고속철도차량(KTX, KTX II) 감속구동장치를 대상으로 실물시험과 실차시험을 수행함으로써 고장이 없는 감속구동장치의 이상진단에 필요한 진동특성분석을 실시하였다.

• Smart Structures and Systems
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• 제21권5호
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• pp.571-582
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• 2018

Track irregularities of high-speed Maglev lines have significant influence on ride comfort. Their adjustment is of key importance in the daily maintenance of these lines. In this study, an adjustment method is proposed and track irregularities analysis is performed. This study considers two modules: an inspection module and a vehicle-guideway coupling vibration analysis module. In the inspection module, an inertial reference method is employed for field-measurements of the Shanghai high-speed Maglev demonstration line. Then, a partial filtering, integration method, resampling method, and designed elliptic filter are employed to analyze the detection data, which reveals the required track irregularities. In the analysis module, a vehicle-guideway interaction model and an electromagnetic interaction model were developed. The influence of the measured line irregularities is considered for the calculations of the electromagnetic force. Numerical integration method was employed for the calculations. Based on the actual field detection results and analysis using the numerical model, a threshold analysis method is developed. Several irregularities modalities with different girder end's deviations were considered in the simulations. The inspection results indicated that long-wavelength irregularities with larger girder end's deviations were the dominant irregularities. In addition, the threshold analysis of the girder end's deviation shows that irregularities that have a deviation amplitude larger than 6 mm and certain modalities (e.g., M- and N-shape) are unfavorable. These types of irregularities should be adjusted during the daily maintenance.

• 한국전산구조공학회논문집
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• 제21권3호
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• pp.225-232
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• 2008

과적차량은 도로 및 교량 구조물과 도로 횡단 시설물 등에 손상요인으로 작용하므로 시설물의 내구성을 단축시켜 이에 따른 유지보수 비용을 증가시킨다. 기존의 단속 시스템은 많은 문제점을 내포하고 있어서 이에 대한 대처방안이 요구되고 있다. 이에 따라, 본 논문에서는 주행중인 과적차량의 지능형 무인과적 단속 시스템 개발을 위하여 유비쿼터스 센서네트워크 시스템을 구성하고, 무선통신프로토콜을 통한 실내성능실험으로 축중 WIM센서 선정, 하중 및 온도에 따른 변수, 자율공간 송수신 거리 실험을 통해 U-도로 과적차량 무인관리 시스템의 가능성을 검토하였다. 그리고 고속 주행 상태에서도 차량의 하중 측정이 가능한 High Speed WIM Sensor의 성능에 대해 검증하였다. 또한 USN구성을 위한 센서의 무선화 테스트를 실시하였다. 본 연구에서 실시한 실험은 기본적으로 고속 WIM센서와 함께 USN의 구성과 Internal/External Network의 완전 무인, 무선화 시스템을 통한 사용자 중심의 시스템을 구축하는 것이 최종 목적이므로 향후 WCDMA/HSDPA를 이용한 External Network의 구성과 실제 과적 단속 적용을 위하여 Test Bed를 통한 실험이 실시되어야 할 것이다.

• 한국소음진동공학회논문집
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• 제13권7호
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• pp.539-547
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• 2003

The prototype of Korean high speed train(KHST), composed of two power cars, two motorized cais and three trailer cars, has been designed, fabricated and tested. In this paper. the body vibration has been reviewed from the viewpoint of the vehicle's safety, the ride comfort and the vibration limits for components and sub-assemblies mounted on the car-body using by analytical method and experimental method. The on-line test of KHST has been tarried out up to 260 ㎞/h in the KTX line and the results of the on-line test show that KHST has no problems in the vehicle's safety. the comfort ride and the vibration limits at this speed. And the characteristics of body vibrations has been Predicted at 300 ㎞/h and 350 ㎞/h by fitting curve about the measured acceleration signals.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1725-1731
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• 2003

A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.36-42
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• 1998

In this study, active muffler was designed and was manufactured for exhaust noise reduction of commercial vehicle, then experiment of real vehicle was conducted. In a manufactured active muffler, because the flow of exhaust noise in tail pope outlet are become a plane wave, the global reduction if radiation noise from outlet and the placement of error microphone to avoid the exhaust gas of high temperature could be implemented. In control algorithm, reduction of noise of engine driving frequency and harmonic frequency can be archieved using proposed reference signal including a fixed speed state(2,000rpm, 3,000rpm, 4,000rpm) and a run-up speed state(2,000rpm$\rightarrow$4,000rpm) is accomplished with the active muffler installed in vehicle.