• Journal of the Korean Society for Railway
• /
• v.19 no.1
• /
• pp.11-19
• /
• 2016

The flows around a high speed train are very important because they could affect the aerodynamic characteristics such as drag and acoustic noise. Especially the boundary layer of flows could represent the characteristic of flows around the high speed train. Most previous studies have focused on the boundary layer region along the train length direction for the side of the train and underbody. The measurement and analysis of the boundary layer for the roof side is also very important because it could determine the flow inlet condition for the pantograph. In this study, the roof boundary layer was measured with a 1/20 scaled model of the next generation high speed train, and the results were compared with full-scaled computational fluid dynamics results to confirm their validity. As a result, it was confirmed that the flow inlet condition for the pantograph is about 85% of the train speed. Additionally, the characteristics of the boundary layer, which increases along the train direction, was also analyzed.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.53 no.11
• /
• pp.589-595
• /
• 2004

This paper presents a modeling and simulation of a grid-connected wind turbine generation system with respect to wind variations, starting of large induction motor and three-phase fault in the system, and investigates voltage variations of the system for disturbances. It describes the modeling of the wind turbine system including the drive train model, induction generator model, and grid-interface model on MATLAB/Simulink. The simulation results show the variation of the generator torque, the generator rotor speed, the pitch angle, terminal voltage, system voltage, fault current, and real/reactive power output, etc. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction for wind speed variations, starting of a large induction motor causes a voltage sag due to a large starting current, and a fault on the system influences on the output of the wind turbine generator.

• Journal of Korean Physical Therapy Science
• /
• v.17 no.3_4
• /
• pp.11-21
• /
• 2010

Purpose: To Provide 3 main principles that needs to be changed for clinical practice and suggest the frame of clinical practice in accordance with the change of generation. Methods: We reviewed literatures related with Clinical Practice. Results: The purpose of physical therapy is to maintain the client's motor and functional ability and enhance the quality of lifestyle. To carry out the principles of clinical practice effectively all the physical therapist must be able to comprehend as follows. First, physical therapy can be different generation by generation. Second, technical terminology must be used when communicate. Third, There are certain ways of process in physical therapy. Conclusion: Physical therapist that is heath care professional occupation in health related, is in need of constant endeavor. Also physical therapist must train oneself self-directed learning.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2008.10a
• /
• pp.33-41
• /
• 2008

The longest tunnel has been halted at Daekwanryung by the failure of the host country of the Winter Olympiad in 2014, but modern High-Power TBM will come to Korea to excavate these long tunnels to establish the better horizontal connection between the western and eastern countries to improve the strong powerful logistic strategy of Korean peninsula. Train operation provides a key function of air movements in a long underground tunnel, and heat generation from transit vehicles may account of the most heat release to the ventilation and emergency systems. This paper indicates the optimal fire suppress services and safety provision for the long railway tunnel which is designed twin tunnel with length 22km in Gangwon province of Korea. The design of the fire-fighting systems and emergency were prepared by the operation of the famous long-railway tunnels as well as the severe lessons from the real fires in domestic and overseas experiences. Designers should concentrate the optimal solution for passenger's safety at the emergency state when tunnel fires, train crush accidents, derailment, and etc. The optimal fire-extinguishing facilities for long railway tunnels are presented for better safety of the comfortable operation in this hard rock tunnel of eastern mountains side of Korea. Since year 1900, hard rock tunnel construction has been launched for railway tunnels in Korea, tunnels have been built for various purposes not only for infrastructure tunnels including roadway, railway, subway, and but also for water and power supply, for deposit food, waste, and oils etc. Most favorable railway tunnel system was discussed in details; twin tunnels, distance of cross passage, ventilation systems, for the comfortable train operations in the future.

• International Journal of Computer Science & Network Security
• /
• v.23 no.5
• /
• pp.121-127
• /
• 2023

A 500 km/h linear motor high speed terrestrial transportation service is planned to launch 2027 in Japan. In order to support 5G service in the train, the Sub-carrier spacing frequency of 30 kHz is planned to be used instead of common 15 kHz sub-carrier spacing to mitigate Doppler effect in such high-speed transportation. In addition, to increase the cell size of 5G mobile system, plural Base Station antenna will transmit the identical Down Link (DL) signal to form the expanded cell size along the train rail. In this situation, forward and backward antenna signals will be Doppler shifted by reverse direction respectively and the receiver in the train might suffer to estimate accurate Channel Transfer Function (CTF) for its demodulation. In this paper, Delay and Doppler Profiler (DDP) based Channel Estimator is proposed and it is successfully implemented in signal processing simulation system. Then the simulated performances are compared with the conventional Time domain linear interpolated estimator. According to the simulation results, QPSK modulation can be used even under severe channel condition such as 500 km/h, 2 path reverse Doppler Shift condition, although QPSK modulation can be used less than 200 km/h with conventional Channel estimator.

• Journal of KIISE:Computing Practices and Letters
• /
• v.12 no.2
• /
• pp.119-128
• /
• 2006

As dialogue systems are widely required, the research on natural language generation in dialogue has raised attention. Contrary to conventional dialogue systems that reply to the user with a set of predefined answers, a newly developed dialogue system generates them dynamically and trains the answers to support more flexible and customized dialogues with humans. This paper proposes an evolutionary method for generating sentences using interactive genetic programming. Sentence plan trees, which stand for the sentence structures, are adopted as the representation of genetic programming. With interactive evolution process with the user, a set of customized sentence structures is obtained. The proposed method applies to a dialogue-based train booking agent and the usability test demonstrates the usefulness of the proposed method.

• International Journal of Contents
• /
• v.8 no.3
• /
• pp.83-93
• /
• 2012

In this paper, we propose a novel method that automatically generates real character images to familiarize existing OCR systems with new fonts. At first, we generate synthetic character images using a simple degradation model. The synthetic data is used to train an OCR engine, and the trained OCR is used to recognize and label real character images that are segmented from ideal document images. Since the OCR engine is unable to recognize accurately all real character images, a substring matching method is employed to fix wrongly labeled characters by comparing two strings; one is the string grouped by recognized characters in an ideal document image, and the other is the ordered string of characters which we are considering to train and recognize. Based on our method, we build a system that automatically generates 2350 most common Korean and 117 alphanumeric characters from new fonts. The ideal document images used in the system are postal envelope images with characters printed in ascending order of their codes. The proposed system achieved a labeling accuracy of 99%. Therefore, we believe that our system is effective in facilitating the generation of numerous character samples to enhance the recognition rate of existing OCR systems for fonts that have never been trained.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.125-131
• /
• 2011

TSI(Technical Specification for Interoperability) is the highest technical specification in the Europe Railway and is composed by assessment items and essential requirements included by safety, reliability, availability, health, environment protection and technical compatibility. It is used on the research and development in the next generation railway technical. Currently, TSI procedures have been asked to bid for high speed rail business in Europe and Brazil. Also, all the railway systems such as infrastructure, signaling, electric and rolling stock system corresponding with standard of TSI procedures are exported and imported. Recently, Safety Critical System which has been studied on future railway R&D business in Korea is the state of the art train control system. And it is needed for system assessment of TSI procedures before system test and operation. In this paper, basic research is performed for analyzing TSI procedures suitable for the state of the art train control system in Korean railway.

• Journal of IKEEE
• /
• v.12 no.4
• /
• pp.234-238
• /
• 2008

We demonstrate a simple method to generate a stable 40 GHz pulse train at 1550 nm by spectral filtering of a 10 GHz mode.locked pulse source using a fiber Fabry-Perot interferometer (FFPI). A high finesse FFPI with a 40 GHz free spectral range blocks successfully unwanted spectral components of a 10 GHz pulse source and passes only 40 GHz spaced spectral lines ensuring pulse repetition-frequency quadruplication of the input pulses.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.6
• /
• pp.696-702
• /
• 2012

In this study, a noncontact laser ultrasonic system is proposed for rail defect detection. An Nd-Yag pulse laser is used for generation of ultrasonic waves, and the corresponding ultrasonic responses are measured by a laser Doppler vibrometer. For the detection of rail surface damages, the shape of the excitation laser beam is transformed into a line. On the other hand, a point source laser beam is used for the inspection of defects inside a rail head. Then, the interactions of propagating ultrasonic waves with defects are examined using actual rail specimens. Amplitude attenuation was mainly observed for a surface crack, and reflections were most noticeable from an internal damage. Finally, opportunities and challenges associated with real-time rail inspection from a high-speed train are discussed.