• 대기
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• 제31권2호
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• pp.157-170
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• 2021

To investigate the effect of snowfall on the traffic of general roads in Gangwon-do, case analysis was performed in Gangneung, Pyeongchang, and Chuncheon using ASOS (Automated Synoptic Observing System) snowfall data and VDS (Vehicle Detector System) traffic data. First, we analyzed how much the traffic volume and speed decrease in snowfall cases on regional roads compared to non-snow cases, and the characteristics of monthly reduction due to snowfall were investigated. In addition, Pearson correlation analysis and regression analysis were performed to quantitatively grasp the effect of snowfall on traffic volume and speed, and sensitivity tests for snowfall intensity and cumulative snowfall were performed. The results showed that the amount of snowfall caused decrease both in the traffic volume and speed from usual (non-snowfall) condition. However, the trend was different by region: The decrease rate in traffic volume was in the order of Gangneung (17~22%), Chuncheon (14~17%), and Pyeongchang (11~14%). The decrease rate in traffic speed was in the order of Chuncheon (9~10%), Gangneung (8~9%), Pyeongchang (5~6%). No significant results were found in the monthly decrease rate analysis. In all regions, traffic volume and speed showed a negative correlation with snowfall. It was confirmed that the greater the amount of traffic entering the road, the greater the slope of the trend line indicating the change in snowfall due to the traffic volume. As a result of the sensitivity test for snowfall intensity and cumulative snowfall, the snowfall information at intervals of 6-hours was the most significant.

• Agricultural and Biosystems Engineering
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• 제7권1호
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• pp.13-17
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• 2006

The planocentric gear, known as wobble mechanism, has been used for speed reducing mechanism as an ingenious mechanism. The modem application can be found in the backrest adjusting mechanism of a vehicle reclinable seat, fluid pumps and aircraft hoist and winches. Higher speed reduction ratios, high load capacity, lower weight, and compactness are the main advantages of this gear. This paper presents velocity and static force analysis to investigate the friction lock of the planocentric gear. The rectilinear tooth profile is used to maximize the speed reduction ratio. The equivalent linkage system is used for the analysis of instantaneous motion. As the results, the transmission efficiency of the planocentric gear is found and the friction lock of the system is determined for the friction coefficients of journals. A numerical example that illustrates the developed analysis is presented.

• 한국기계가공학회지
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• 제17권2호
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• pp.118-123
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• 2018

Coil guns are known worldwide as inexpensive space launch vehicles. The principle of Fleming's right-hand rule allows the coil gun to accelerate the projectile by applying enormous voltage to the solenoid coil. This study was performed to improve the speed of the coil gun using MATLAB, a commercially available numerical program for high launching force of electromagnetic projectiles. To maximize the speed of the projectile, the largest coil of American wire gauge was used, and the number of windings in the radial and axial directions of the solenoid coil was optimized. Optimal length of the projectile was obtained by calculating the optimal aspect ratio between the axial length of the solenoid coil and the length of the projectile.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.964-967
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• 2007

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.849-854
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• 2008

For the running safety assessment of Saemaul train passing through curves, an analysis model for multibody system has been developed. By using this model and ADAMS/Rail, sensitivity analyses depending on the variation of parameters related to the derailment coefficients have been conducted. According to the increase of running speed, the derailment coefficient and unload ratio were increased. At high speed, the derailment coefficient and unload ratio of left wheel showed higher than right wheel. If the cant increased, the derailment coefficient and unload ratio increased. but decreased based on the balance cant value by the curvature and running speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.346-348
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• 1997

This paper presents microprocessor-based real-time speed and position detection by inductive radio loop in new transportation system, such as magnetically levitated train system, rubber tyred train, and linear-motor car. The constant elapsed time method is used in this study for high accurate detection over a wide speed range. And for reliability and safety of the system, it is duplicated and data-bus level comparison is performed by fail-safe comparator.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.506-510
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• 2008

Ramjets are capable of much higher specific impulse than liquid rocket engines for high speed flight in the atmosphere. Ramjets, however, cannot generate thrust at low flight speed. Therefore, an additional propulsion device to accelerate the ramjet vehicle to a supersonic speed is required. In this study, we propose a novel ramjet propulsion system with a $H_2O_2$/Kerosene rocket as the accelerator for initial stage. In order to test the feasibility of this concept, consecutive reactors was built; one for the decomposition of $H_2O_2$ and the other for kerosene combustion. Decomposed $H_2O_2$ jet was injected to combustor through converging nozzle from gas generator and over this hot oxygen jet, kerosene was injected by spay injector. Through the various test cases, hypergolic ignition test was carried out and steady combustion was achieved.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.267-274
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• 2009

To predict efficiency of Interior Permanent Magnet Synchronous Motors(IPMSM) and to cope with the demagnetization risk of permanent magnets used in the IPMSM, accurate iron analysis of the IPMSM is very important at the motor design stage. In the analysis, we calculate the operation condition such as rotor speed and current angle. and then, we analyzed the iron loss of the machine for electric vehicle according to its driving condition. From the analysis results, it was shown that the harmonic iron losses of stator are larger than before at field-weakening region. In addition, it was revealed that rotor iron loss mainly induced by stator slot-ripples is independent of current angle and only varied according to the speed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1653-1661
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• 2008

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. In the area of wayside structure, the stability of track structure and train run shall be evaluated through the review of impact by increased speed by developed train on track structure. The study thus was intended to evaluate the impact on track while a tilting train is running the conventional line(ballast track), which is vulnerable to accelerated train speed. The evaluation of tilting train test running the part of Honam line was conducted to identify the impact on existing track performance by tilting train. To identify the performance of each part of track components while tilting train and high speed train were running the existing line, wheel load, rail bending stress, vertical displacement of rail and sleeper were compared so as to evaluate the expected impact by tilting train for improving the train speed.

• 사물인터넷융복합논문지
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• 제8권6호
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• pp.55-63
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• 2022

최근 중국에서 중대형 도시철도의 급속한 발전으로 고속철도의 총 운행거리와 총 EMU(Electric Multiple Units) 수가 증가하고 있다. 고속 EMU의 시스템 복잡성은 지속적으로 증가하고 있으며, 이는 장비의 안전성과 유지보수의 효율성에 대한 더 높은 요구사항을 제시한다. 현재 중국의 고속 EMU의 유지보수 모드는 여전히 계획적인 유지보수 및 고장보수에 기반한 사후 유지보수 방식을 채택하고 있어 유지보수가 미흡하거나 과도하게 이루어지며, 장비 고장 처리의 효율성을 떨어뜨리고 유지보수 비용을 증가시킨다. PHM(진단 및 예측관리)의 지능형 운영 및 유지관리 기술을 기반으로 합니다. 본 논문은 고속 EMU의 서로 다른 시나리오의 다중 소스 이기종 데이터를 통합하여 "차량 시스템-통신 시스템-지상 시스템"의 통합 PHM 플랫폼을 구축하고, 장비 고장 메커니즘을 인공지능 알고리즘과 결합하여 고속 EMU의 트랙션 모터에 대한 고장 예측 모델을 구축한다. 고속 EMU의 안전하고 효율적인 작동을 보장하기 위해 고장 예측 및 정확한 유지보수를 사전에 수행해야 한다.