• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.81-82
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• 2015

차세대 고속철도 기술개발 사업을 통해 개발된 통합차상신호 시스템은 국내에서 운영중인 세가지 신호시스템인 ATP, ATC, ATS의 신호를 모두 처리하면서 열차 운행의 중단 없이 열차 운행구간을 이동하게 된다. 현재 통합차상신호시스템의 신뢰성과 안정성 확인을 위해 차세대 고속철도 시제차인 HEMU-430X에 탑재하여 시운전을 진행중에 있는데, 시운전이 여객열차의 영업운전 사이에 진행되기 때문에 다양한 실험과 검증에 많은 제약이 따른다. 이러한 제약 사항을 해결하고 다양한 실험과 개선 활동을 위해 통합차상신호시스템을 실험실내에서 테스트할 수 있는 통합차상신호시스템용 시뮬레이터의 개발이 필요하게 되었고, 본 논문에서는 통합차상신호시스템용 시뮬레이터 개발에 관한 내용을 다룬다.

• International Journal of Railway
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• v.2 no.4
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• pp.147-151
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• 2009

Railway vehicles equipped with semi-active suspension system can improve the ride quality of car bodies. Semi-active suspension system is usually applied onto high speed train, and therefore higher running safety requirement is proposed. The influence of semi-active suspension system on safety of vehicles running on straight line and curve line is studied, and the influences of sky hook damping coefficient and system time-delay on operation safety of cars fitted with semiactive suspension system is analyzed. The results show that the vehicles equipped with semi-active suspension system, not only the vibration of car body is decreased, it can also give little influence on running safety of cars, as a result, it will not endanger the running safety of cars.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1839-1852
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• 2008

Japanese government actively took part in the TSR modernization. the amount of trade between Russia & Japan increased increasingly by 55%, as the individual income increases in Russia, it becomes a big scale consuming market, therefore Japan concentrates on lobby to push into the russian continent and also Japanese government will participate in aggressively to the cooperation with Russian government, loaning to the TSR modernization & trade insurance, high speed train introduction, and introduction of transport system. this study checks and analyzes the japan's concrete methods & strategy to advance to the continent, and also this case can be applied to South korea, if TKR corridor is continuously blocked. I want to review the cooperation of north & south, and the project of continental railways.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.275-280
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• 2008

Recently the railway safety is very important issue in Korea because there are lots of changes like the separation of operation and facility of national rail network, the inauguration of high speed train and Daegu subway fire accident. Railway safety management system is based on risk assessment of rolling stocks, electrical system, signaling, operation & maintenance and human element. With this process, railway risk will be reduced as low as reasonably acceptable level. Through risk assessment on accident data, this study predicted the current risk level of railway electrical system and presented the proper safety ensuring measures.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1024-1028
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• 2008

The ballast, one of track components, plays an essential role as intermedium in transmitting train load to subgrade safely, and the deterioration of ballast directly effects the growth of track irregularity. In this study, we determined the main factor of ballast deterioration was miniature of ballast gravel caused MTT(Multiple Tie Tamper) works and accumulated traffic loads. To estimate the deterioration characteristics of ballast, we carried out field test through track construction for test and the model test simulating the actual operation environment, have done a comparative analysis with the sample's result(crushing rate) of high-speed railroad running actually.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.864-867
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• 2016

In high speed railway system, LTE(Long Term Evolution) based LTE-R(LTE-Railray) mobile technology is used to supply various control signal required for safty operation of train. In this paper, railway communication technology be used in railway communication system based on LTE-R is investigated in focused on application services. Standardization trends for LTE-R technology are also considered. Results of this study can be used as basic data for research and development of LTE-R and railway mobile communication.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3515-3524
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• 2023

A reinforcement learning framework is proposed for the control problem of outlet steam pressure of the once-through steam generator(OTSG) in this paper. The double-layer controller using Proximal Policy Optimization(PPO) algorithm is applied in the control structure of the OTSG. The PPO algorithm can train the neural networks continuously according to the process of interaction with the environment and then the trained controller can realize better control for the OTSG. Meanwhile, reinforcement learning has the characteristic of difficult application in real-world objects, this paper proposes an innovative pretraining method to solve this problem. The difficulty in the application of reinforcement learning lies in training. The optimal strategy of each step is summed up through trial and error, and the training cost is very high. In this paper, the LSTM model is adopted as the training environment for pretraining, which saves training time and improves efficiency. The experimental results show that this method can realize the self-adjustment of control parameters under various working conditions, and the control effect has the advantages of small overshoot, fast stabilization speed, and strong adaptive ability.

• Journal of the Korean Geotechnical Society
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• v.36 no.3
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• pp.5-14
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• 2020

The railway concrete track has been increasingly adopted for high-speed train such as KTX due to its high running stability, improved ride quality for the passengers, and low maintenance cost. However, excessive settlement of the railway concrete track has been monitored at embankment sections of the ◯◯ High-speed Line, resulting in the concerns on the safety of railway operation. In order to establish an effective maintenance plan for the concrete track railway exceeding the allowable residual settlement, it is essential to reasonably predict their long-term settlement behavior during the public period. In this study, we developed a model for predicting the long-term settlement behavior of concrete track using recurrent neural network (RNN) and examined the applicability of the developed model.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.186-192
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• 1998

This paper presents a high performance low switching PWM technique or the propulsion system of railway such as subway and high speed train. In order to achieve the continuous voltage control to six-step and s low harmonics with low switching frequency under 500Hz, the synchronous technique is combined with a space vector overmodulation and implemented by using DSP. Improved performance and a validation of proposed method are showed by the digital simulation and the experimental results using a 1.65MVA IGBT VVVF inverter and inertia load equivalent to 160 tons railway cars.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.137-145
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• 2007

In traditional financial theory, the discount cash flow model(DCF or NPV) operates as the basic framework for most analyses. In doing valuation analysis, the conventional view is that the net present value(NPV) of a project is the measure of the present value of expected net cash flows. Thus, investing in a positive(negative) NPV project will increase(decrease) firm value. Recently, this framework has come under some fire for failing to consider the options of the managerial flexibilities. Real option valuation(ROV) considers the managerial flexibility to make ongoing decisions regarding the implementation of investment projects and the deployment of real assets. The appeal of the framework is natural given the high degree of uncertainty that firms face in their technology investment decisions. This paper suggests an algorithm for estimating volatility of logarithmic cash flow returns of real assets based on the Black-Sholes option pricing model, the binomial option pricing model, and the Monte Carlo simulation. This paper uses those models to obtain point estimates of real option value with the G7- HSR350X(high-speed train).