• Proceedings of the KSR Conference
• /
• 2009.05b
• /
• pp.437-443
• /
• 2009

Generally speaking, the uniqueness of Korea for the high-speed railway rolling-stock is mainly perceived through the travel over the high-speed electric railway by passengers, which consists of the organization of space in the coach and its interior design. For such purpose, it is necessary to build a series of independent cultures with high-speed railway i.e. to have the development of design technologies oriented to harmonizing human beings, their society and culture with the systematic integration of production technologies to support the culture and its substructure foundation which constitute the frame of superstructure in the society, by defining the relationships with travelers on the high-speed railway as well as enhancing the comfort and convenience of high-speed railway through drawing up the development of links with the systematic integration among lines of technologies on the basis of 'User Train Interface. This thesis aims at introducing the study carried out to build the evaluation standards of performance outputs for 'HEMU-400X rolling-stock Design' derived from the performance for the first year in the research 'Development of Technologies for the Next-Generation High-Speed Railway' as part of "Development Project for the Future Railway Technologies" from 2007.

• Journal of Internet Computing and Services
• /
• v.24 no.5
• /
• pp.37-50
• /
• 2023

In general, PLL or DDS are mainly used as precise and stable frequency synthesis methods. For stable operation, a PWM frequency generation algorithm was designed and implemented using FPGA. This is an algorithm that creates a frequency 8,192 times the target frequency and then performs the D flip-flop 13 times to generate multiple frequencies with a precision of 1 Hz. Using the designed algorithm, it is applied to the Berthing system for stopping trains in station. The applied product was developed and tested against the existing operating system to confirm its superior performance in terms of frequency generation accuracy.

• Journal of the Korean Society for Railway
• /
• v.20 no.1
• /
• pp.20-30
• /
• 2017

Due to the evolution of wireless communications technology, Long Term Evolution (LTE), which is a $4^{th}$ generation mobile communications system, has been adopted as a railway communications system. This LTE Railway (LTE-R) system is composed of various elemental functions, which are largely categorized into public safety and wireless communications for train control. Research on the public safety functions of railway communications have their roots in TRS based national public safety communication systems, and research on wireless communications functions for train control have their roots GSM-R, which is utilized by the ETCS in Europe. Based on these circumstances, this paper first analyzes the requirements for developing public safety technology in LTE-R, and compares those requirements with the functions of public safety LTE (PS-LTE), which is being deployed for the first time in the world by the South Korean government. Based on an analysis of the common and specific functions of LTE-R and PS-LTE, we conclude that there is little problem in integrating LTE-R and PS-LTE from the perspective of functionality. Second, this paper provides a comparison of the LTE-R requirements for the Quality of Service (QoS) with those of GSM-R utilized by the ETCS. This offers a guideline to allow LTE-R to be applied to a 500km/h train control system.

• International Journal of Computer Science & Network Security
• /
• v.23 no.10
• /
• pp.1-10
• /
• 2023

This paper proposes a method to extend Inter-Carrier Interference (ICI) canceling Orthogonal Frequency Division Multiplexing (OFDM) receivers for 5G mobile systems to spatial multiplexing 2×2 MIMO (Multiple Input Multiple Output) systems to support high-speed ground transportation services by linear motor cars traveling at 500 km/h. In Japan, linear-motor high-speed ground transportation service is scheduled to begin in 2027. To expand the coverage area of base stations, 5G mobile systems in high-speed moving trains will have multiple base station antennas transmitting the same downlink (DL) signal, forming an expanded cell size along the train rails. 5G terminals in a fast-moving train can cause the forward and backward antenna signals to be Doppler-shifted in opposite directions, so the receiver in the train may have trouble estimating the exact channel transfer function (CTF) for demodulation. A receiver in such high-speed train sees the transmission channel which is composed of multiple Doppler-shifted propagation paths. Then, a loss of sub-carrier orthogonality due to Doppler-spread channels causes ICI. The ICI Canceller is realized by the following three steps. First, using the Demodulation Reference Symbol (DMRS) pilot signals, it analyzes three parameters such as attenuation, relative delay, and Doppler-shift of each multi-path component. Secondly, based on the sets of three parameters, Channel Transfer Function (CTF) of sender sub-carrier number n to receiver sub-carrier number l is generated. In case of n≠l, the CTF corresponds to ICI factor. Thirdly, since ICI factor is obtained, by applying ICI reverse operation by Multi-Tap Equalizer, ICI canceling can be realized. ICI canceling performance has been simulated assuming severe channel condition such as 500 km/h, 8 path reverse Doppler Shift for QPSK, 16QAM, 64QAM and 256QAM modulations. In particular, 2×2MIMO QPSK and 16QAM modulation schemes, BER (Bit Error Rate) improvement was observed when the number of taps in the multi-tap equalizer was set to 31 or more taps, at a moving speed of 500 km/h and in an 8-pass reverse doppler shift environment.

• The KSFM Journal of Fluid Machinery
• /
• v.19 no.3
• /
• pp.14-18
• /
• 2016

The power generation system using cold energy, which evolves in a large amount during the vaporization process of the liquefied natural gas, was designed in favor of the Rankine cycle with a mixed refrigerant as the working fluid. In this study it is intended to identify the allowable limits of the working fluid composition in respect of equipment safety in the Rankine cycle-type power generation system driven by the cold energy. The thermodynamic properties of the working fluid, which is a hydrocarbon mixture, were calculated with the Peng-Robinson model. In the steady state simulation of the power generation system by using a commercial tool Aspen HYSYS, the feed conditions of LNG Test Bed Train No.1 along with some necessary assumptions were incorporated. The results indicated that deterioration of the mechanical performance of the equipment as well as its safety would be brought about if contents of $C_2H_6$ and $C_3H_8$ in the mixture become, respectively, too high or too low.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.17 no.10
• /
• pp.2643-2657
• /
• 2023

Scene graphs are structured representations that can clearly convey objects and the relationships between them, but are often heavily biased due to the highly skewed, long-tailed relational labeling in the dataset. Indeed, the visual world itself and its descriptions are biased. Therefore, Unbiased Scene Graph Generation (USGG) prefers to train models to eliminate long-tail effects as much as possible, rather than altering the dataset directly. To this end, we propose Geometric and Semantic Improvement (GSI) for USGG to mitigate this issue. First, to fully exploit the feature information in the images, geometric dimension and semantic dimension enhancement modules are designed. The geometric module is designed from the perspective that the position information between neighboring object pairs will affect each other, which can improve the recall rate of the overall relationship in the dataset. The semantic module further processes the embedded word vector, which can enhance the acquisition of semantic information. Then, to improve the recall rate of the tail data, the Class Balanced Seesaw Loss (CBSLoss) is designed for the tail data. The recall rate of the prediction is improved by penalizing the body or tail relations that are judged incorrectly in the dataset. The experimental findings demonstrate that the GSI method performs better than mainstream models in terms of the mean Recall@K (mR@K) metric in three tasks. The long-tailed imbalance in the Visual Genome 150 (VG150) dataset is addressed better using the GSI method than by most of the existing methods.

• International Journal of Control, Automation, and Systems
• /
• v.3 no.4
• /
• pp.533-541
• /
• 2005

In this paper, a wind turbine with power splitting transmission, which is realized through a novel three-shaft planetary, is presented. The input shaft of the transmission is driven by the rotor of the wind turbine, the output shaft is connected to the grid via the main generator (asynchronous generator), and the third shaft is driven by a control motor with variable speed. The dynamic models of the sub systems of this wind turbine, e.g. the rotor aerodynamics, the drive train dynamics and the power generation unit dynamics, were given and linearized at an operating point. These sub models were integrated in a multidisciplinary dynamic model, which is suitable for control syntheses to optimize the utilization of wind energy and to reduce the excessive dynamic loads. The important dynamic behaviours were investigated and a wind turbine with a soft main shaft was recommend.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1289-1291
• /
• 2002

본연구는 한국형 고속전철용 신호시스템 시제품들의 시험평가 중 운용환경시험의 항목, 시험기준, 방법 그리고 시험결과에 대해 설명하였다. 이 한국형 고속전철용 신호시스템의 운용환경 시험을 위해 국내외 적용 가능한 규격 또는 기준을 조사분석하여 본 시험에 적합한 기준 및 방법을 도출하였으며, 이를 바탕으로 개발된 시제품들에 대한 운용환경시험을 수행하였다. 본 시험을 통해 개발된 시제품들의 운용환경 특성이 검증되었으며, 이후에는 이들 시제품들의 현장시험을 수행할 예정이며 이를 통해 최종적인 한국형 신호시스템의 시제품의 시험평가를 마무리할 예정이다.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1457-1465
• /
• 2011

The saloon light is the device that can offer convenience and comfort to the driver and passenger when the train is operated at night or in the tunnel. Generally, The fluorescent type saloon for the rolling stock have been used, but the problems that are short life and the generation of heat have been brought about because the saloon lihgts of rolling stock are supposed to operated continuously long time, and high power consumption. So, the development of new type of saloon lights has been requested in order to solve these problems. And recently the various LED type lights have been developed and LED type saloon lights for rolling stock also has been developed. Therefore, we survey the characteristic, function and needed condition of the LED type saloon lights for rolling stock, and analyze the good and bad point, and then research the complement of weak point. We want to find the direction and develop the design of future LED saloon light type.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.3
• /
• pp.211-216
• /
• 2013

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.