• 한국철도학회논문집
• /
• 제6권3호
• /
• pp.209-214
• /
• 2003

When a rail vehicle transverses tight curves, it often emits an intense, high-pitched squeal. This squeal has always been noticed as one of the most disturbing noise sources of railway systems. At present, we cannot predict squeal noise that is influenced by a large number of dependent parameters. In this study, we performed structural analysis to find out the frequency of the wheel and measured squeal noise at Seoul subway. We also tested reduction effectiveness of squeal noise through rail lubricator.

• 대한의생명과학회지
• /
• 제13권1호
• /
• pp.39-45
• /
• 2007

Numerous psychological stressors playa role in development of the cardiovascular disease. The aim of this study was to determine whether a combined mental activity with experimental subway noise affects hematological physiology. Fifty-four healthy volunteers were divided group I which underwent subway noise (n=24) and group II which underwent a combined mental activity with subway noise (n=30). Venous blood samples were collected for measuring CBC, prothrombine time (PT), activated partial thromboplastine time (APTT), erythrocyte sedimentation rate (ESR), D-dimer and high sensitive C-reactive protein (H-CRP) levels before, 50 min of stress task (S-50m) and 60 min of recovery (R-60m). Changed ratios of granulocyte, lymphocyte, monocyte and platelet counts at S-50m and R-60m were higher in group II compared to group I. RBC count and hematocrit level in group I increased whereas those in group II decreased at S-50m. PT, APTT and ESR in the both groups were shortened at R-60m and the decreased ratios were high in group II compared to group I. H-CRP and D-dimer in the both groups were elevated at S-50m and R-60m while the increased ratios in group II were greater than those in group I. These observations imply that a combined mental activity with experimental subway noise may be a stressor which affects hematological physiology.

• 한국음향학회지
• /
• 제34권2호
• /
• pp.138-145
• /
• 2015

환경 소음의 무절제한 노출이 청력 손실로 이어질 수 있다는 보고는 익히 알려져 있지만, 지하철 실내 소음과 휴대용 음향기기 음량에 따른 이중 소음 노출에 대한 탑승객들의 청력 손실 여부는 많은 연구들에서 여전히 진행 중이다. 본 연구는 지하철 실내 소음 하에서 탑승객들이 이어폰을 이용하여 개인음향기기 사용 시 음향 반사 역치와 소음속 어음인지도가 어떻게 변화하는 지 확인하고자 하였다. 20대의 젊은 건청 성인 40명을 대상으로 실험 그룹과 대조그룹으로 각각 20명씩 구분하였다. 실험 전 모든 대상자에게 5개의 주파수에서 음향반사역치검사와 0, -5 dB SNR에서 문장검사를 실시하였다. 실험 그룹은 60분간 73.45 dBA의 실제 서울도심지하철의 평균 실내 소음 강도를 들으며 개인별 선호 음량으로 이어폰을 통해 좋아하는 음악을 들었고, 대조그룹은 동일강도의 지하철 소음에만 노출된 채 신문 혹은 잡지를 읽었다. 60분간의 지하철 소음 노출 후 음향반사역치검사와 소음 속 문장검사를 재실시하여 기준선과 비교하였다. 소음 노출 전 후 비교 시, 두 그룹 간 음향반사역치는 유의미한 차이가 없었다. 그러나 소음 속 문장 검사결과에서는 실험 그룹의 어음인지도가 소음 노출 후 유의하게 하락하였다. 본 결과를 근거로 지하철 탑승객이 일정기간 동안 지하철 실내 소음에 노출된 채 반복적으로 음악을 듣는 습관이 지속될 시 일시적인 어음인지력 저하의 위험이 예상 될 것이라고 생각한다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 추계학술대회 논문집
• /
• pp.1448-1453
• /
• 2008

This paper deals with the estimation methods of ground-borne noise generated by subway. Generally, numerical method using by ground model is used to prediction of ground borne noise. However, this method is needed a lots of time to make an analysis and model. In this paper, we describe empirical formula that is based on experimental data for subway and estimate the ground-borne noise propagated from underground station that is builded in the near future to building.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.750-750
• /
• 2001

Todays, according to development of traffics, there are so many tunnels around us. Tunnels are used for trains, subway trains, cars, etc. Especially for subway, all of its routes are tunnels. So the noise of the subway train cannot radiated out of the station and the noise level in the station and train cabin is so high. There are some methods to reduce this noise and one of them is using absorbing materials. But the area of the tunnel and station is very large, so it is important to determine the effective position and amount of absorbing materials before attaching them. In this study, we studied the effect of sound absorbing materials in the tunnel using boundary element method. We applied BEM for general boundary conditions. With BEM calculations, we found the effect of absorbing materials and effective positions for the subway tunnel and station.

• 소음진동
• /
• 제7권2호
• /
• pp.293-300
• /
• 1997

Noise and vibration induced by subway operation is one of the major problem for the residents living nearby railway tracks. Many scientists and engineers have been working on proposing the more accurate prediction equation of noise and vibration to provide the better residential environment. Some predictiction equations were determined to compare the measurement value of a noise obtained from the inside of a residential area. It was observed that the condition of a soil type is one of the major parameter which should be considered to obtain the more accurate prediction value of a noise.

• 대한환경공학회지
• /
• 제33권4호
• /
• pp.243-250
• /
• 2011

부산지하철 3개 노선에 대한 소음도 조사 및 비교 평가가 이루어 졌다. 차량이 역을 다 빠져 나간 순간부터 차량이 다음 역에 도착할 때까지를 기준으로 하여 차량 내부에서의 평균 소음값을 측정하였다. 또한 차량이 역사 도착 시 측정과 차량이 역사 출발 시 측정으로 나누어서 측정하였다. 주간시간대(오전9시~오후6시)와 야간시간대(오후6시~오후10시)로 구분하여 측정하였으나 주 야간 차이가 크지 않아 주 야간의 차이를 두지 않고 전체적으로 평균을 취했다. 2010년 5월과 7월 두 차례 부산지하철의 차량실내 소음도를 측정하여 실험에 대한 재현성을 검정하였다. 노선별 스크린 도어 효과, 도상조건, 열차차종 및 노선별 곡률반경 변화에 따른 소음도 차이가 조사되어 졌다. 부산지하철 3개 노선 중 2호선의 소음도가 가장 높았으며 이에 대한 방안도 강구 되었다. 스크린도어가 미설치된 역이 설치된 역에 비하여 소음도가 약 10 dB(A) 정도 높았으며 S 자형의 급곡선부에서 소음도가 높음이 확인되었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문초록집
• /
• pp.338.2-338
• /
• 2002

Passengers in automobile or train are exposed to a worse noise environment when they are in the tunnel than in the open field. This is due to a relatively higher space density of sound energy by multiple reflection phenomenon of noise generated by operation of transportaton vehicles from tunnel wall compared to open field. In this study, noise characteristics of subway train running through a tunnel were investigated at straight/cruved track and tunnel type(semi circula/box). (omitted)

• 한국환경과학회지
• /
• 제15권3호
• /
• pp.287-292
• /
• 2006

The purpose of this paper is to evaluate the noise level and source, reduce the subway line II noise. As a result of measurement of subway line II in Busan the highest value section of uproad line was from Jigegol to Motgol by 89 dB(A). The sections of conversation and listening interference(over 80 dB(A)) were 21 sections(55%) of 38 sections. Among these sections, 15 sections(71%) were produced rolling noise, 3 sections(14%) squeal noise, 2 sections(10%) braking noise and 1 section(5%) fan noise, and then a main noise source was the rolling noise. In case of downroad line, the highest value section was from Busan Metro Art Museum to Centum city, Motgol to Jigegol by 88 dB(A). The sections of conversation and listening interference(over 80 dB(A)) were 18 sections(47%) of 38 sections. Among these sections, 15 sections(83%) produced rolling noise, 2 sections(11%) squeal noise and 1 section(6%) braking noise were investigated in this study. and then a main noise source was the rolling noise.

• 한국소음진동공학회논문집
• /
• 제18권10호
• /
• pp.1014-1023
• /
• 2008

Subway electric trains need to be faster for accommodation of long distance passengers. The faster run of the existing trains results in deterioration of ride quality due to noise and vibration. To reduce the noise and vibration of the electric train, a running test of the electric train was performed and an ADAMS/Rail model was set up to verify the running test results. The experimental results show that the sources of the cabin noise and vibration basically comes from the irregularity of the railroad track and the deterioration of the connection part between cabin and bogie. Consequently for mitigation of noise and vibration of the electric train, the redesign of the center pivot with softer stiffness and the minimization of rail irregularity are necessary. the frequent maintenance of the train will lead to better comport.