• ETRI Journal
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• 제43권3호
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• pp.377-388
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• 2021

Owing to the difficulties associated with conducting millimeter-wave (mmWave) field measurements, especially in high-speed train (HST) environments, most propagation channels for mmWave HST have been studied using methods based on simulation rather than measurement. In this study, considering a linear cell layout in which base stations are installed along a railway, measurements were performed at 28 GHz with a speed up to 170 km/h in two prevalent HST scenarios: viaduct and tunnel scenarios. By observing the channel impulse responses, we could identify single- and double-bounced multipath components (MPCs) caused by railway static structures such as overhead line equipment. These MPCs affect the delay spread and Doppler characteristics significantly. Moreover, we observed distinct path loss behaviors for the two scenarios, although both are considered line-of-sight (LoS) scenarios. In the tunnel scenario, the path loss exponent (PLE) is 1.3 owing to the waveguide effect, which indicates that the path loss is almost constant with respect to distance. However, the LoS PLE in the viaduct scenario is 2.46, which is slightly higher than the free-space loss.

• 한국인터넷방송통신학회논문지
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• 제18권5호
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• pp.103-109
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• 2018

5G 목표 중 하나는 기차와 같이 고속으로 이동하는 사용자에 대해 고속의 데이터 속도를 제공하는 것이다. 따라서, High speed train (HST) 시나리오와 같은 높은 이동성 시나리오는 5세대 통신 시스템의 전형적인 시나리오가 될 것으로 예상된다. HST가 급속하게 발전함에 따라 열차 승객에게 무선 통신 데이터를 전송 해야하며, 이용자들의 요구하는 통신 속도는 점차 증가하고 있다. HST 사용자는 현재 HST 통신 시스템의 기능을 벗어나는 위치 또는 속도에 관계없이 높은 네트워크 용량과 안정적인 통신 서비스를 요구한다. 따라서, 5세대 이동통신으로 사용될 mm대역에서 5G 이동통신 시스템에 맞춰 전송 frame을 구성하고 HST 통신 시스템을 구현하고 HST 시나리오에서 광대역 비 정지 MIMO HST 채널에 대한 성능을 분석한다.

• ETRI Journal
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• 제40권1호
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• pp.39-50
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• 2018

More people prefer using rail traffic for travel or for commuting owing to its convenience and flexibility. The railway scenario has become an important communication scenario in the fifth generation era. The communication system should be designed to support high-data-rate demands with seamless connectivity at a high mobility. In this paper, the channel characteristics are studied and modeled for the railway tunnel scenario with straight and curved route shapes. On the basis of measurements using the "Mobile Hotspot Network" system, a three-dimensional ray tracer (RT) is calibrated and validated for the target scenarios. More channel characteristics are explored via RT simulations at 25.25 GHz with a 500-MHz bandwidth. The key channel parameters are extracted, provided, and incorporated into a 3rd-Generation-Partnership-Project-like stochastic channel generator. The necessary channel information can be practically realized, which can support the link-level and system-level design of the communication system in similar scenarios.

• 한국항만학회지
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• 제11권2호
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• pp.305-320
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• 1997

The objective of this paper is to analysis & forecast on the change in spatial structures of southeast region by development of the Seoul-Pusan high-speed Rail. To measure the spatial structures, it was used the method of mean center and standard distance among of centrographic measures as analytical tools. The changes of spatial structures patten over time and space in the southeast region were surveyed using population and employment data of 57 zones. And also, to forecast the spatial structures of the southeast region after opening of the Seoul-Pusan high-speed rail, it was supposed three(3) scenarios which designed using influential area with centering around of the proposed high-speed rail stations. Therefore, the results of this research indicate as follows; 1) The spatial structures of population is showed a trend of continual concentration toward Ulsan city area, and also the spatial structures of employment is showed a trend of continual dispersion over time. 2) The forecast of three93) scenarios supposed after opening of the Seoul-Pusan high-speed rail in 2006 show a change of the spatial structures with both population concentration and employment dispersion. In the meantime, the rapid increase of population and wide dispersion of employment is reform with centering around HSR stations which builted in the southeast region after opening of high-speed rail. 3) It shall furnish valuable data to establish the development strategy of urban and local region, and also forecast the change of spatial structures about population and employment in influential area which passed on high-speed rail line & stations by method of mean center and standard distance among of centrographic measures as analytical tools.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.2035-2039
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• 2008

In this paper, degrades modes of high-speed trains are deduced and analyzed by using Systems engineering architecture methods for a preceding research of hazard identification and scenarios deduction of the KTX. Moreover, Vigilance System of the high-speed trains is analyzed.

• Wind and Structures
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• 제35권6호
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• pp.405-418
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• 2022

The aerodynamic behaviour of a CRH high-speed train under three infrastructure scenarios (flat ground, embankment, and viaduct) in the presence of a crosswind was simulated using a 1/8th scaled train model with three cars and the IDDES framework. The time-averaged and instantaneous flow field around the model were examined. The employed numerical algorithm was verified through a wind tunnel test, and the grid and timestep resolution analyses were conducted to ensure the reliability of the data. It was noted that the flow around the rail line was different under different infrastructure scenarios, especially in the case of the embankment, which degraded the aerodynamic performance of the train under the crosswind. The flow around the train on the flat ground and viaduct was different, although the aerodynamic performance of the train was similar in both cases. Moreover, the viaduct accidents were noted to have the most critical consequences, thereby requiring the most attention. The aerodynamic performance of the train on the windward track of the embankment under the crosswind was worse than that of the train on the leeward track. But for the other two infrastructure scenarios, the aerodynamic performance of the train on the windward track is relatively dangerous, which is mainly caused by the head car. These observations suggest that the aerodynamic behaviour of the train on an embankment under a crosswind must be carefully considered and that certain wind protection measures must be adopted around rail lines in windy areas.

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.33-44
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• 2017

In this paper, the dynamic responses of train-bridge system under one-way and two-way high-speed train passing are studied. The 3D finite element modeling is used and the bridge and train are modeled considering their details. The created model is validated by the results of the dynamic field test. To study the effect of train speed, different train passing scenarios are analyzed, including one-way passing, two-way passing in different directions at same speeds, and two-way passing in different directions at different speeds. The results show that the locations of maximum acceleration are different in one-way and two-way passing modes, and the maximum values in two-way passing mode are higher than those in one-way passing mode, while the maximum accelerations in both modes are almost identical. The displacement and acceleration values in different scenarios show peaks at speeds of 260 and 120 km/h, due to the proximity of the natural frequencies of the bridge and loading frequencies of the train at these speeds.

• International Journal of Railway
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• 제5권2호
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• pp.84-88
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• 2012

Derailment due to wheel failure would cause a tremendous social and economical cost in service operation. It is necessary to evaluate quantitatively the safety with respect to high-speed train. Although the safety of railway wheel has been ensured by an regular inspection, all critical defects cannot be detected in inspection cycles and the wheel has been replaced because a defect quickly become critical for safety. Therefore, it is important to calculate quantitatively the fracture limit and remnant life of damaged railway wheel in wheel-rail system. In present paper, the critical crack size of wheel for high-speed train is simulated based on fracture scenario and the safety of wheel is evaluated.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.686-693
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• 2003

An intensive study was conducted for crashworthiness structural design of recently developed Korean High Speed Train. Two nam design concepts are setup to protect the both crews and passengers from serious injury at heavy collision accidents, and to reduce damages of the train itself at light collision accidents. For occupant protection a collision against a movable 15 tons rigid obstacle at 110 kph and a train-to-train collision at 30 kph were selected as accident scenarios for the heavy collisions based on the train accident investigations. A train-to-train collision at 8 kph was used for the light collisions. The crashworthiness behaviors of KHST have been evaluated numerically using the finite element method. Also, one-dimensional collision analyses show good crashworthy responses in a full rake consist and 3-dimensional shell element analyses do in the front-end structures of the power car. Occupant analyses and sled tests demonstrated that KHST performs well enough to protect occupants under the considered accident scenarios.

• 신재생에너지
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• 제10권2호
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• pp.29-39
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• 2014

This study examines the future variability of surface wind speed and solar radiation based on climate change scenario over the Korean Peninsula. Climate change scenarios used in this study are RCP 4.5 and 8.5 with a 12.5 km horizontal resolution. Climate change scenario RCP 4.5 and 8.5 reproduce the general features of wind speed over the Korean Peninsula, such as strong wind speed during spring and winter and weak wind speed during summer. When compared with the values of wind speed and solar radiation of the future, they are expected to decrease current wind and solar resource map. Comparing the resource maps using RCP 4.5 and 8.5 scenarios, wind speed and solar radiation decrease with increasing greenhouse gas concentration. Meteorological resource maps of future wind and solar radiation should be improved with high resolution for the industrial application.