• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1250-1252
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• 2003

This Paper presents Sigma-Delta Modulation(SDM) schemes to generate switching waveform for a high-power factor boost-type rectifier. The SDM scheme can be implemented by simple digital algorithm unlike conventional PWM schemes with several hardware, and has the characteristics of spectrum-spreading and noise-shaping effects, which are profitable in harmonic reduction of input current in the boost-type rectifier. The comparison results of their spectrum performances shows that the 1st-order SDM has better harmonic suppression effect than conventional PWM scheme and Dithered SDM scheme.

• Journal of Navigation and Port Research
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• v.29 no.9
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• pp.795-800
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• 2005

Nowadays, road transportation which has played a key role in the market of both passenger and freight transportation is facing with a serious problem, the traffic congestion causing a delay of transportation. Therefore, railroad transportation is considered as an attractive alternative mode of inland transportation due to its inherent merits in mass transportation such as relatively low cost compared with road transportations, less air pollution and noise than other mode ets. In this paper, therefore, we examine the current situation of railroad transportation markets including TKR(Trans- Korean Railway}, TSR(Trans-Siberian Railway} and prospects for the connection of TKR-TSR. And then we examine the structure of the container transportation market by railroad in Korea with a brief analysis of the traffic volume of TKR-TSR.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.991-993
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• 2003

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.

• Journal of Environmental Impact Assessment
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• v.22 no.6
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• pp.739-744
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• 2013

Recently, railroad construction becomes an alternative considering environmental merits such as mass transportation, safety, economy and energy efficiency. Also railroad can have 3 to 4 times better in economy compared to road construction. However, long line and unavoidable sensitive areas hinders railroad construction often resulted in ecosystem degradation. This paper reviewed 27 cases of EIS submitted during 2003-2006 and reviewed major issues on Animal-Plants and Landscape. Noise-Vibration (13.5%), Water Quality (13.5%), Wastes (10.8%) appeared to be most frequent factors to supplement. Route selection in the railroad is the most sensitive issues so that public participation and hearing should be involved in the early stage of the process and social and cultural factors also must be considered to make a final decision on the railroad route location and selection.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.7 s.100
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• pp.859-864
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• 2005

Noise map is a presentation of existing data or predicted noise situation in terms of noise indicator. However, it has shortcoming for assessing the number of people exposed, or the number of dwellings affected to any relevant limit values of noise level in certain areas. In this study, so called over-ride value noise mapping is Proposed to make up for the shortcoming by using over-ride function of object-oriented programming and it is to show the guard of the area where it is satisfied the standard of option, or it is not satisfactory. Over-ride value noise map data is combined with topography layer, population and house statistics, and GIS space statistical analysis. The over-ride value noise mapping can also be applied to make the road traffic noise map, the railroad noise map, the aircraft noise map, and the industrial site noise map. This can express noise damage information more exactly.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.48-53
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• 2016

Noise and vibration pollution is emerging to people in high speed trains. And it is difficult to realization of eco-friendly railway system at noise problem. The railway internal noise is 73dB on average and over 80dB in the loudest section. In order to reduce noise, there are passive methods that are far from noise sources and theother active noise reducion method. In this paper, we propose a method of reduce noise by measure and estimate the noise condition of train environment using Bone-Conduction device. We use an anti-phase waveform for canceling of noise characteristic. With this new system, the noise from surrounding environments can be reduced.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.283-289
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• 2010

Recent advance of digital camera results in that image signal processing techniques are widely adopted to railroad security management. However, due to the nature of railroad management many images are acquired in low light level environment such as night scenes. The lack of light causes lots of noise in the image, which degrades image quality and causes errors in the next processes. 3D noise reducing techniques produce better results by using consecutive sequence of images. On the other hand, they cause degradation such as motion blur if there are motions in the sequence. In this paper, we use an adaptive weight filter to estimate more accurate motions and use the result of the adaptive filter to 3D result to improve objective and subjective mage quality.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.911-916
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• 2005

Noise map is a presentation of existing data or predicted noise situation in terms of noise indicator. However, it has shortcoming for assessing the number of people exposed, or the number of dwellings affected to any relevant limit values of noise level in certain areas. In this study, so called over-ride value noise mapping is proposed to make up for the shortcoming by using over-ride function of object-oriented programming and it is to show the guard of the area where it is satisfied the standard of option, or it is not satisfactory. Over-ride value noisemap data is combined with topography layer, population and house statistics, and GIS space statistical analysis. The over-ride value noise mapping can also he applied to make the road traffic noisemap, the railroad noisemap, the aircraft noisemap, and the industrial site noisemap This can express noise damage information more exactly.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.165-172
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• 2017

High frequency squeal noise can be generated when a railroad vehicle runs a sharp curved section; this noise causes environmental complaints and excessive wear on the wheel and the railroad track. In this paper, curved squeal noise experiments on a commercial railway were carried out to investigate this phenomenon. The relationship of the squeal noise pressure level, the frequency characteristics, the railway running speed, and the modal behavior of the wheel were investigated. At the same time, the lateral motion of the wheel relative to the rail was captured using a video camera; wheel movement was calculated when the noise was generated. queal noise occurred at the highest level at the inner front wheel; this phenomena is considered to be related to the lateral vibration response characteristics of the wheel. It can be seen that the magnitude of this squeal noise is not directly related to the increase in vehicle speed.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.99-105
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• 2007

Since 1990s, the railway noise has been researched and developed in our nation. First of all, what's causing the noise and how to eliminate the cause of the noise must be found out. Secondly, cutting off the propagation path of the noise from the noise source to the receiving points. In this study the characteristics of prediction formula for the assessment of railway noise used in some nations including Korea were investigated. In order to develop the prediction formula of the railway noise, the noise radiated from railway vehicle, rails and sleepers, characteristics of noise barrier, velocity of train, ground effects, roughness should be analyzed and predicted. Especially, on the basis of acoustics, the characteristics of source are applied to acoustic power and directivity information.