• The Journal of the Acoustical Society of Korea
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• v.27 no.4
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• pp.191-199
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• 2008

In this paper, we propose a MWF-PMC noise processing method which enhances the input speech by using Mel-warped Wiener Filtering (MWF) at pre-processing stage and compensates the recognition model by using PMC (Parallel Model Combination) at post-processing stage for speech recognition in noisy environments. The PMC uses the residual noise extracted from the silence region of enhanced speech at pre-processing stage to compensate the clean speech model and thus this method is considered to improve the performance of speech recognition in noisy environments. For recognition experiments we dew.-sampled KLE PBW (Phoneme Balanced Words) 452 word speech data to 8kHz and made 5 different SNR levels of noisy speech, i.e., 0dB. 5dB, 10dB, 15dB and 20dB, by adding Subway, Car and Exhibition noise to clean speech. From the recognition results, we could confirm the effectiveness of the proposed MWF-PMC method by obtaining the improved recognition performances over all compared with the existing combined methods.

• Fire Science and Engineering
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• v.22 no.2
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• pp.49-56
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• 2008

Smoke propagation for the Daegu Metro fire is reproduced by a reduced-scale model experiment. The three-story station building was modeled with 1/20-scale, and the tunnel connected to the platform was not completely modeled because of its length. To include the flow resistance the tunnel provides the mesh screens were used in the model. The fire scenario was selected based on the fire growth rate of the metro car seat where the fire initiated. The time when smoke arrived at each compartment in the station building was measured by thermocouples and visualization. Regarding fire ventilation, the air supply that has been accepted as conventional design in a subway metro building intensifies smoke spread. The results show that the whole building was filled with smoke in about 10 minutes in case of no ventilation.

• Journal of the Korean Society for Railway
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• v.11 no.2
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• pp.120-125
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• 2008

The Ministry of Environment established a guide line Indoor Air Quality Management guidelines in Public Facilities in December 2006. As the items of the guideline, $CO_2$ (Carbon dioxide) and PM10 (Particulate matter). Therefore trains and subway need to control air quality. The indoor thermal environment in passenger car is very important for the enhancement of the amenity and health of passengers. Many researchers have studied it not for train but for building. So, in this study, we have performed thermal environment in passenger car (KTX, Mugunghwa, Saemaeul), and verified the relation between the PMV (Predicted Mean Vote) and PPD (Predicted Percent Dissatisfied) from September to October 2007. As a result, the average PMV value for each trains are 0.1, 0.22 for KTX, 0 for Mugunghwa, 0.1 for Saemaeul. So it satisfies the ASHRAE Handbook thermal environmental limit (-0.5 < PMV < +0.5).

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.509-517
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• 2008

Rolling stock is the method of railway transportation. Especially, in the subway system which has short headways particularly during the rush hours, even one train's trouble on the main line might influence the whole line. Accordingly, to prevent a train trouble on the main line, high expense is used for the maintenance parts, workforce and facilities, etc. according to the preventive maintenance program. Therefore, in designing a EMU, emphasis should be put on the minimization of trouble and its extending influence on the mainline with the priority of safety and reliability. Seoul subway line 5 is the line that complements the first stage Seoul subway(lines 1,2,3 and 4) and is built deeply with many curved sections causing lots of dust. Studies were made to find out the importance of car design, selection of specifications and continuous maintenance on the basis of the analysis and countermeasure of the line 5 EMU inverter trouble case.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.239-244
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• 2008

일반적인 피난모델은 건물 화재시의 상황을 예측해보기 위해 제작된 것들이다. 이들을 사용하여 철도차량 내부에서의 피난상황을 예측해보기 위해서는 각 출입문에서의 유동에 대한 연구가 필요하다. 특히 터널 내 정차와 같이 차량바닥과 지면의 차이가 존재하는 경우는 현재 자료가 없는 상황이다. 이는 철도차량뿐만 아니라 차량에서 나간이후에 경유하게 되는 터널이나 역사의 피난을 평가하는 데도 매우 중요한 자료이다. 그러므로 본 연구에서는 지하철 차량에서의 피난 현상 중에서 차량과 차량간의 이동과 차량에서 선로로의 이동에 대한 현상을 실험을 통해 분석해보았다.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.571-588
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• 2011

With the development of the technology, the usage of the car has been increased to the allowed limit of the road and has caused global warming and air pollution. Subway is good transit system with punctuality, safety and eco-friendliness, but it needs relatively much money for construction considering the needs of transit. So it is hard to balance the finance. Many developed countries have adopted advanced transit system including tram for the linking small and medium sized cities after 1980s, due to the relatively low construction cost. This paper reviews the way to increase the role of tram which is planed to be introduced to the local governments as a kind of Advanced transit system.

• MALSORI
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• no.57
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• pp.153-164
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• 2006

The MMSE-STSA based speech enhancement algorithm is widely used as a preprocessing for noise robust speech recognition. It weighs the gain of each spectral bin of the noisy speech using the estimate of noise and signal power spectrum. In this paper, we investigate the influence of parameters used to estimate the speech signal and noise power in MMSE-STSA upon the recognition performance of noisy speech. For experiments, we use the Aurora2 DB which contains noisy speech with subway, babble, car, and exhibition noises. The HTK-based continuous HMM system is constructed for recognition experiments. Experimental results are presented and discussed with our findings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1857-1862
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• 2012

It is very difficult to construct and manager public transit, like subway, in small city. In this paper, we suggest full electric vehicle sharing service framework as a public transit system in small city. The suggested system will reduce environment pollution and increase resource usage efficiency. The simulation result shows that the suggested electric vehicle sharing system can reduce traffic congestion and lower city road stress.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.167-172
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• 2010

This paper is to implement HSDPA-CPE that can provides WiFi terminal with wireless Internet service through the connection to HSDPA wireless network. This system aims to support HSDPA interface in upstream, and WiFi and 100Mbps Ethernet interface in downstream. So, this system can provide multiple Internet customers with wireless Internet service by using WiFi terminal in subway, car, ship, and so on, and WiFi terminals that be registered in HSDPA service can be connected to Internet.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.57-64
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• 2007

RIMS（Rolling Stock Information Maintenance System)　was installed in structure which it can analyze the data base in need of credibility maintenance. So it could accumulate real data without repulsion of working spot. Information system was installed not following to system but following to working spot. The development of RIMS project was started from March 29, 2001 and it has been operating from October 12, 2004 in Chang-dong Car depot for light maintenance in charge subway line4. So substantial data base was accumulated for three years. This study calculated all RAMS data by analyzing data base accumulated in RIMS and used in dada base about credibility maintenance and found investigation of propriety, expectation of the life cycle cost, the improvement plan on credibility of sorts of cars and formation about the cycle of repairing and maintenance. This got MKBSF MKBF and MTBF about devices and sorts of line4 Rolling Stocks for it.