• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1034-1039
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• 2001

Recently. development of a subway as a public transport has been increased rapidly. Therefore, large noise, which induced from vehicle itself as well as frictions between rails and train, may inflict a considerable damage to the adjacent structure and cause discomfort to neighboring residents. Nevertheless, adequate design guidelines to reduce outdoor noise are not yet established. The present work carried out a survey on the influence of outdoor subway noise using questionnaires. Also or noise measurements levels in those are as were performed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1197-1200
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• 2003

Urban subways usually make environmental problems because subway vibrations are transmitted to building structures. However, when the buildings are designed, vibrations due to subway are not usually considered in advance. This results in many environmental vibration problems after buildings are constructed. This study was carried out to set up and evaluate a pre-assessment technique for the environmental impact of urban subway vibration on newly planned buildings near a subway line. for this purpose, semi-emperical method was set up and vibration measurements were made on site in accordance with construction schedule. Computer simulation was also performed using ANSYS software to predict the building vibration and compared with the measured results for evaluation of the pre-assessment technique.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.678-684
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• 2007

This research has defined the factors of noise in cars during subway train services, which is surfacing as a new environmental trouble. It shows additional accomplishment of a discerning analysis on the standard of noise regulation as well as its seriousness. According to the Enforcement Regulations for Noise and Vibration under the Ministry of Environment and its standard noise regulation figure 70dB, we divided two groups of which train noise figures are over and under 70dB respectively, and used their 359 results about noise, geometric structures and operation elements, for this analysis. The results and suggestions are following. First of all, when we discern the seriousness of noise in a train, the track type has mattered in geometric structure and the velocity in operation elements. Therefore, when we construct subway from now on, we should take the track type in consideration and establish plans to keep proper speed in respect of operation. Secondly, the established discernment model in this research can be used in making alternative plans or improvement of subway trains hereafter, showing relatively high accuracy of estimation. Consequently, the readjustment of geometric structure and operation elements is needed, not to make it over the regulation standard of noise in case the noise in train is serious. The discriminant model of this research can be used as elementary material for comfortable and safe subway trains, making the estimation of noise seriousness possible.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.446-454
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• 2011

The noise of the subway has become a social issue and includes very complex reasons. The friction between rail and train wheel is the most important reason of the noise. In this study, we developed MFI(Multi Fluid Injection) System which sprays the mixed fluid(water, anticorrosive and lubricant) on the rail when the train is approaching to reduce the friction. To verify the system's effect, we measured the internal and external noise of the running train. The measured and analyzed results show that MFI system reduce the noise of the running subway.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.265-272
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• 1998

In this paper, the intoner noise reduction for subway railroad vehicles was studied by improving transmission loss of carbody panels and side doors, and on-line tests were conducted to examine the exterior noise levels at various running conditions. Also the transmission loss for design candidates of the carbody specimen was measured in two reverberation rooms. From the results of the tests, side door gap is the most dominant factor affecting the Interior noise level of subway railroad cars with a sliding typed side door. The next one is revealed to transmission loss of a floor panel. To improve the transmission loss of the carbody, many activities were conducted such as, treatment of resilient and sound-absorbing materials and reducing the gap of the side door by adopting a brush and rubber, etc. The estimated interior noise level for modified car which is designed with improved carbody panels is lower than original car by about 5㏈.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.439-441
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• 2007

The seoul metropolitan subway has installed 8 lines and about 500 stations to transport 5 million passengers everyday. The underground air pollution level in the subway stations is very severe status, which is very harmful to the commutators and its personals. Although subway roles as such a massive and huge transportation system, the subway doesn't adapt yet any real-time air monitoring system. They have only some hand-held type detector equipments for monitoring air pollution. Therefore subway passengers are exposed to the harmful air pollution environment. The most harmful environmental parameters among the air pollution are known as the dust and sound noise dB level in the subway station. Because the dust is consisted of very small particles, we can't see them easily in dark condition on the platform, but it is very harmful. The monitoring system for air pollution is developed using embedded system attached with 6 different environmental sensors. This system monitors air pollution of dust sound noise, gas, temperature, humidity, inflammable gas, toxic gas in the subway ?station. The sensor unit of the ARM-CPU board and sensor transmits real time environmental data to the main server using Zigbee wireless communication module and TCP/IP network. The main control server receives and displays the real-time environmental data, and it send alarms to the personals when high level value.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.329-334
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• 2009

Subway is used as a useful transportation method to solve the metropolitan traffic problem for its advantages of being not only accurate, safe and massive, but also of not producing any exhaustion gas in compare with the other ground transportation systems. However, noise inside the car due to concrete based rail track and tunnel structure has become a social problem. So, an analysis on the noise characteristics according to their routes and locations was made on the basis of the actually measured results from the trial run. To reduce the interior noise of subway train, the side part of rolling stock should have a noise blocking system fur low band frequency noise, the floor of it should have that for medium range frequency noise and the side part as well as lower part of it should have good noise reduction and absorption function.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.64-68
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• 1998

본 연구의 목적은 수도권 지하철차량의 소음과 진동에 방음차륜(또는 탄성차륜)이 어느 정도의 효과를 가져오는가를 평가하기 위한 것이다. 실차시험을 통하여 일체차륜이 장착된 차량과 방음차륜이 장착된 차량의 차내소음 및 차체진동을 비교하여 보았다. 그 결과 방음차륜은 지하철차량의 소음과 진동에 효과가 있음을 알 수 있었다. 그러나 실제 적용은 소음과 진동 이외에도 여러 가지 측면에서의 검토가 이루어져야만 가능할 것이다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.114-121
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• 1995

Problems of noise and vibration induced by subway operation became one of the major factor when new subway 1 me is under consideration. One of the most economic method in reducing the noise and vibration is the increasement of the tunnel mass. . Vibration of the massive tunnel structure has been measured induced by subway operation. STEDEF system which was adopted by Seoul Metropolitan Subway Bureau has been proved that more than 99% of the vibration has been decreased at the bottom of the railway track. Most of the vibration measured inside and outside of the tunnel showed that their peak frequency is around SOHz or 100Hz. The propagation characteristics of vibration in massive tunnel , wave propagate in three directions. Overall frequency in the range of 0 to 125H2 horizontal transmission usually increase, while vertical transmission decreases about 50% in the range of 0 to 25Hz and 90Hz to 125Hz regardless of modal shape.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.738-742
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• 2005

Ground vibration at Gil-dong in Seoul induced by the 5th ling of Seoul Subway is predicted using various prediction methods and compared with measured vibration. Also, several issues on the improvement of prediction methods are discussed. Furthermore, as an alternative vibration source, measured vibration acceleration level(VAL) on the tunnel wall of the Bundang line of Seoul Subway is applied to the prediction of the VAL at the location mentioned previously. Then requirements accompanied to the suggestion of the new vibration source appropriate to the condition of Seoul Subway.