• 한국소음진동공학회논문집
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• 제21권7호
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• pp.637-642
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• 2011

The DMT freight is judged that economic performance is good because can increase cargoes than existing freight. However, the existing freight cars, each with a different balance to the body structure is bogie because the vibrations may occur. Thus, by minimizing vibration over the existing freight securing the safety of the driving if you will not have major problems in cargoes. In this study, multi-body dynamic analysis tool, VI-Rail using the actually Gyeongbu Railroad line and an empty, full freight condition include curve radius, track irregularity, The DMT freight of the derailed wagons were assessed for safety analysis. Full and empty freight conditions for parity in the Gyeongbu Railroad line(Dongdaegoo${\leftrightarrow}$Kyungsan) derailment safety analysis, such as derailment coefficient and the wheel unloaded, echoing the curve and the orbit is affected by the irregularity was found. Full freight condition than the empty conditions showed a significant derailment safety. Overall, the limits of derailment coefficient(Q/P = 0.8) and wheel unload decrement limits(${\triangle}P/P$ = 0.6) is less safe with me confirmed that the derailment safety.

• 한국철도학회논문집
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• 제20권3호
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• pp.299-310
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• 2017

본 연구에서는 3-piece 마찰 웨지 화차의 주행성능을 예측하기 위해 ADAMS/View에서 독립하중 마찰 웨지 모델을 개발하였다. 마찰 웨지 모델은 볼스터의 좌우, 수직방향에 따른 마찰을 각각 구현해줄 수 있다. 개발된 마찰 웨지 모델은 ADAMS/Rail 차량 모델에 적용하여 동역학 해석 결과를 얻었다. 대상차량은 임계속도 210km/h를 가진다. 직선 안정성 해석에서 UIC518에 근거해 차체의 횡, 수직방향 한계 가속도에 만족하는 것을 확인하였다. 300R 곡선에서 해석 적용 속도는 70km/h로 UIC518에 근거해 차체, 대차의 한계 가속도에 만족하였다. 또한 "철도차량 안전기준에 관한 규칙"의 윤중감소율, 횡압, 탈선계수에 만족하는 것을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.776-783
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• 2003

A low speed wind tunnel test was conducted for full-scale model of an unmanned aerial vehicle (UAV) in Korea Aerospace Research Institute (KARI) Low Speed Wind Tunnel(LSWT). The purpose of the presented paper is to illustrate the general aerodynamic and performance characteristics of the UAV that was designed and fabricated in KARI. Since the testing conditions were represented minor portions of the load-range of the external balance system, the repeatability tests were performed at various model configurations to confirm the reliability of measurements. Variations of drag-polar by adding model components such as tails, landing gear and test boom are shown, and longitudinal and lateral aerodynamic characteristics after changing control surfaces such as aileron, flap, elevator and rudder are also presented. To explore aerodynamic characteristics of an UAV with model components build-up and control surface deflections, lift curve slope, pitching moment variation with lift coefficients and drag-polar are examined. The discussed results might be useful to understand the general aerodynamic characteristics and drag pattern for the given UAV configuration.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1304-1312
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• 2005

The ride and noise characteristics of a vehicle are significantly affected by the vibration transferred to the body through the chassis mounting points in the engine and suspension. It is known that body attachment stiffness is an important factor of idle noise and road noise for NVH performance improvement. The body attachment stiffness serves as a route design aimed at isolating the vibration generated inside the car due to the exciting force of the engine or road. The test result of the body attachment stiffness is shown in the FRF curve data; the stiffness level and sensitive frequency band are recorded by the data distribution. The stiffness data is used for analyzing the parts that fail to meet the target stiffness at a pertinent frequency band. The analysis shows that the target frequency band is between 200 and 500 Hz. As a result of the comparison in a mounted suspension, the analysis data is comparable to the test data. From these results, there is a general agreement between the predicted and measured responses. This procedure makes it possible to find the weak points before a proto car is produced, and to suggest proper design guidelines in order to improve the stiffness of the body structure.

• 한국통신학회논문지
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• 제39C권3호
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• pp.255-263
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• 2014

도로변에 설치된 폐쇄회로 카메라를 통해 사고를 감지하여 교통사고 대책반에 전송하는 시스템이 연구되어 많은 성과를 거두고 있다. 더하여 고속도로에서는 고장으로 인한 정지차량이 차량의 흐름을 방해하는 것도 사고로 간주해야 하는 상황이 발생한다. 본 논문에서는 차량의 흐름을 각 차선 별로 모니터링하고 있다가 정지차량이나 사고로 인한 차량흐름의 변화를 감지하여 이를 사고 대책반에 알리는 시스템을 소개한다. 각 차선 별 차량흐름은 레벨 스페이싱 곡선들로서 위치벡터에 대한 Wigner 분포를 이룬다. 여기에 해밀토니안 및 칼로게로 모제 시스템을 적용하면 각 레벨스페이싱 커브간의 간격에 대한 확률식을 얻게된다. 이 식으로부터 변동이 큰 이상 신호를 찾으면 사고 상황과 잘 맞는다. 이것은 한 차선에 대한 이상 신호를 찾는 것과는 다르다. 전체적인 차량 흐름 속에서 찾아야만 사고를 감지하는 효과를 보기 때문이다. 각 차선 별 차량흐름을 모니터링 하는 과정에서 카메라의 특성상 차량의 그림자를 차량으로 오인하게 되면 사고감지에도 영향을 미친다. 이를 방지하기 위해 그림자를 제거하는 방법도 소개한다. 본 시스템의 평가를 위해 베이지안 네트워크 방법을 사용한 시스템과 비교하였다. 특별히 고장으로 인한 정지차량으로 생겨난 차량흐름의 변화를 사고로 인식하는 데는 본 시스템이 우수한 것으로 나타났다.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.114-122
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• 2014

Sensor fusion is the one of the main research topics. It offers the highly reliable estimation of vehicle movement by processing and mixing several sensor outputs. But unfortunately, every sensor has drift which degrades the performance of sensor. It means a single degraded sensor output may affect whole sensor fusion system. Drift in most research is ideally assumed to be zero because it's usually a nonlinear model and has sample variation. Plus, it's very difficult for the acceleration to separate drift from the output signal since it contains many contributors such as vehicle acceleration, slope angle, pitch angle, surface condition and so on. In this paper, modified spline interpolation is introduced as a dynamic temperature compensation method covering sample variation. Using the last known output and the first initial output is suggested to build and update compensation factor. When the system has more compensation data, the system will have better performance of compensated output because of the regression compensation model. The performance of the dynamic temperature compensation system is evaluated by measuring offset drift between with and without the compensation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.140-140
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• 2009

The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEM-type FCs system was integrated by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with variations on mass flow rate and stack temperature. The ranges of the variations are $20{\sim}70^{\circ}C$ on stack temperature and 1~8L/min on $H_2$ volume.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.311-318
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• 2001

The CWR, when installed on the bridge, may introduce extra responses in displacement, stress etc. due to the expansion of bridge girders. To release these responses, a special concern must be put on the CWR on bridges, especially for the long span bridges. Since the risk of derailment of vehicle due to buckling or breakout of the rails on bridges is of importance, the establishment of appropriate guidelines to check the performance of CWR on bridges is crucial for safe operation of train. In this study, using the program CWRAP, specialized for response of rails on bridges, several schemes for constructing CWR on bridges are suggested. In audition, a special concern is given to the bridge with sharp curve which is vulnerable to buckling due to temperature loads.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.628-635
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• 2016

Natural gas reformed hydrogen is used as a fuel of fuel cell vehicle, PSA process is used for the purification of reformed hydrogen. In this study, the performance of CO adsorbent in PSA process was evaluated. Zeolite adsorbents used in the commercial PSA process is used. The physical and chemical properties of adsorbents were characterized using BET apparatus, XRD, and FE-SEM. The breakthrough apparatus modified from GC was used for the CO breakthrough experiment, the quantitative analysis of CO adsorption capacity was performed using CO breakthrough curve. Zeolite 10X and 13X showed superior CO adsorption capacity than activated alumina. The CO adsorption capacity of zeolite 10X is more than twice of zeolite 13X even the BET surface area is low. It seems that the presence of $Ca^{2+}$ cation in zeolite 10X is beneficial to the adsorption of CO.

• 한국산업융합학회 논문집
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• 제22권1호
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• pp.47-54
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• 2019

An experimental study was conducted on the wear and friction responses in sliding tests of a micro-textured surface on laser pattern (LP) steel as reduction gear material in electric guided vehicle. In this research, the friction characteristics of laser pattern steel under different micro texture density conditions were investigated. The friction tests were carried out at sliding speeds of 0.06 m/s to 0.34 m/s and at normal loads of 2 to 10 N. Photolithography method was used to create the dimples for surface texturing purpose. Four different specimens having different dimple densities of 10%, 12.5%, 15%, and 20% were observed respectively. In this research, friction conditions as shown in Stribeck curve were investigated. Furthermore, the microscopic surface was observed using scanning electron microscope. It was found that the dimple density had a significant role on the friction characteristics of laser pattern steel conditioned as reduction gear material in an agricultural vehicle. The duty number showed that the friction condition was hydrodynamic regime. The best performance was obtained from 12.5% dimple density with lowest friction coefficient achieved at 0.018771 under the velocity of 0.34 m/s and 10N load.