• 한국철도학회논문집
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• 제19권3호
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• pp.280-287
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• 2016

지하터널에서 도시철도 운행 중 휠과 레일의 접촉에 의해 먼지가 발생되고, 이 먼지는 도시철도에 기인하는 열차풍에 의해 부유하고, 이 중 일부는 중력침강에 의해 바닥에 침착된다. 이 연구에서는 도시철도 터널에서 먼지농도의 일변화를 조사하였다. 도시철도 운행에 따른 먼지농도의 변화를 쉽게 관측하기 위하여 단일구간의 터널을 측정대상으로 선정하였다. 5nm에서 $20{\mu}m$ 범위의 먼지를 측정하기 위하여 4종류의 입자측정기를 사용하였다. 도시철도가 측정지점을 통과하는 시각을 정확히 파악하기 위하여 3차원 초음파 풍속계와 비디오 카메라를 사용하였다. $50{\mu}g/m^3$ 이하이던 지하터널의 먼지농도는 도시철도의 운행에 의해 $150{\mu}g/m^3$ 이상까지 유의하게 증가하였고, 특히 출근시간대에는 $250{\mu}g/m^3$ 이상으로 크게 높아졌다.

• Asian Journal of Atmospheric Environment
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• 제6권2호
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• pp.96-103
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• 2012

Ambient particulate matter (PM) and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations were measured continuously for 70 days at a Korean elementary school located near a highway. The $PM_{10}$, $PM_{2.5}$, and $PM_1$ values were measured with a light-scattering, multi-channel, aerosol spectrometer (Grimm, Model 1.107). The number concentrations of the particles were measured using a scanning mobility particle sizer and counter (SMPS+C) which counted particles from 11.1 to 1083.3 nm classified in 44 channels. Particle-bound PAHs were measured with a direct reading, photoelectric aerosol sensor. The daily $NO_2$, $SO_2$, and CO concentrations were obtained from a national air-monitoring station located near the school. The average concentrations of $PM_{10}$, $PM_{2.5}$, and $PM_1$ were 75.3, 59.3, and $52.1{\mu}g/m^3$, respectively. The average number concentration of the ultrafine particles (UFPs) was $46,307/cm^3$, and the averaged particle-bound PAHs concentration was $17.9ng/cm^3$ during the study period. The ambient UFP variation was strongly associated with traffic intensity, particularly peak concentrations during the traffic rush hours. Particles <100 nm corresponded to traffic-related pollutants, including PAHs. Additional longterm monitoring of ambient UFPs and high-resolution traffic measurements should be carried out in future studies. In addition, transient variations in the ambient particle concentration should be taken into consideration in epidemiology studies in order to examine the short-term health effects of urban UFPs.

• 한국대기환경학회지
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• 제27권2호
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• pp.142-151
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• 2011

In this study, we have observed PM-10 and $CO_2$ concentration in the subway cabins and analyzed the factors affecting air quality using a multivariate statistical analysis. The measurements have been conducted at Seoul metropolitan subway lines. The results show that the mean concentration of the PM-10 and $CO_2$ inside subway cabins is in the range of 62.6 to 108.0 ${\mu}g/m^3$ and 907 to 2,008 ppm, respectively. $CO_2$ level in specific sections during the rush hours has exceeded air quality guidelines for public transportation, which requires designated train ventilation controls. Correlation and regression analyses of influencing factors imply that $CO_2$ level is severely influenced by the number of passengers and PM-10 level is also correlated with the number of passengers. In particular, PM-10 level in the cabins indicates a positive correlation with outdoor PM-10 level. In addition, the PM concentration has been highly affected by the number of passengers and distance between stations.

• 한국대기환경학회지
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• 제33권3호
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• pp.251-264
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• 2017

Recently, Jeollabuk-do has been reported as a province where the $PM_{10}$concentration is one of the highest levels in South Korea. To explore the characteristics and origins of the $PM_{10}$in Jeollabuk-do, we present one of the first long-term datasets including a statistical analysis of $PM_{10}$concentrations obtained from six cities in the province from 2010 to 2015. During the entire periods, the mean hourly $PM_{10}$concentration was $49.3{\mu}g/m^3$, which correspond to the annual ambient air quality standards for $PM_{10}$in South Korea, and the annual $PM_{10}$concentration of each city showed a similarity in year-to-year variations. In the monthly variation of $PM_{10}$, the $PM_{10}$concentrations showed a maximum value in May that was one of the top levels among the provinces of Korea while the concentrations were dramatically decreased in August showing one of the lowest levels among the provinces in Korea. For the diurnal variation of $PM_{10}$, the $PM_{10}$concentration was enhanced during the rush hours together with gaseous species of $NO_2$, and CO. When the high concentrations of $PM_{10}$were observed (the highest 10% of the $PM_{10}$mass contribution), temperature and relative humidity were low. Using HYSPLIT backward trajectories and cluster analysis for the high $PM_{10}$concentrations, we found that the pollution plumes were transported mainly from China.

• 한국대기환경학회지
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• 제18권2호
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• pp.113-126
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• 2002

This study was carried out to evaluate the temporal (daily, weekly, and seasonal) variations of volatile organic compounds (VOCs) concentrations at a road-side site in a heavy-traffic central area of Metropolitan Taegu. Ambient air sampling was undertaken continuously for 14 consecutive days in each of four seasons from the spring of 1999 to the winter of 2000. The VOC samples were collected using adsorbent tubes, and were determined by thermal desorption coupled with GC/MS analysis. A total of 10 aromatic VOCs of environmental concern were determined, including benzene, toluene, ethylbenzene, m＋p-xylenes, styrene, o-xylene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, and naphthalene. Among 10 target VOCs, the most abundant compounds appeared to be toluene (1.5 ∼ 102 ppb) and xylenes (0.1 ∼ 114 ppb), while benzene levels were in the range of 0.3 ∼6 ppb. It was found that the general trends of VOC levels were significantly dependent on traffic conditions at the sampling site since VOC concentrations were at their maximum during rush hours (AM 7∼9 and PM 7 ∼9). However, some VOCs such as toluene, xylenes, and ethylbenzene were likely to be affected by a number of unknown sources other than vehicle exhaust, being attributed to the use of paints, and/or the evaporation of solvents used nearby the sampling site. In some instances, extremely high concentrations were found for these compounds, which can not be explained solely by the impact of vehicle exhaust. The results of this study may be useful for estimating the relative importance of different emission sources in large urban areas. Finally, it was suggested that the median value might be more desirable than the arithmetic mean as a representative value for the VOC data group, since the cumulative probability distribution (n=658) does not follow the normal distribution pattern.

• 한국대기환경학회지
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• 제29권6호
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• pp.734-744
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• 2013

In this study, the telematics device was installed on the car (OBD-II) to collect the information on the operation conditions from each sample vehicle. Based on the information the domestic driving pattern was analysed and the ratio of cold start length was estimated. As a result of analysis for driving pattern, we found a difference in the frequency of driving on the hourly or seasonal basis. Then, the driving pattern of the rush hours, weekdays, and weekends could be derived. Also, from the study, an average of 2.22 times per day occurred in a single trip and average driving distance for the trip was 15.72 km. In addition, the proportion of cold start length was analyzed to be 16.11%. The seasonal cold start length has big difference from season to season (Winter 26.63%, Summer 8.22%, Intermediate 12.65%). There was an inverse relationship between the outside temperature and ratio of cold start length. In order to improve the accuracy of the cold emission estimation, it is necessary to apply domestic ratio of cold start length that driving pattern and temperature in Korea is reflected.

• 대한교통학회지
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• 제24권7호
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• pp.129-138
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• 2006

서울시는 지난 2004년 7월부터 버스에 준공영제(공공관리, 민영운영)개념을 도입한 후 노선별로 불필요한 운행을 최소화하고 승객편익 및 이용수요 증대를 위해 배차 최적화 모형을 연구. 개발하였다 본 연구는 이러한 노력의 결과물로서 서울시 버스 운영체계에 맞는 노선별 운행대수. 근로조건, 최대 재차인원. 최대/최소 배차간격 등을 제약 조건으로 하고 승객의 대기시간을 최소화하는 Heuristic 배차최적화 모형을 개발하였다. 모형의 적용성을 검증하기 위해 운행 중인 노선에 적용한 결과, 같은 운행대수라도 첨두시 배차간격이 좁혀져 승객편익이 증대되었다. 따라서 개발모형은 여러 제약조건을 고려한 최적 배차계획 수립 및 적용을 가능케 하여 버스운영 효율화에 기여할 것으로 판단된다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권3호
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• pp.1865-1877
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• 2013

Vertical variations of polycyclic aromatic hydrocarbon (PAH) concentrations in $PM_{10}$ were investigated in order to assess the factors controlling their behavior in the urban atmosphere of Bangkok City, Thailand. Air samples were collected every three hours for three days at three different levels at Bai-Yok Suit Hotel (site-1 and site-2) and Bai-Yok Sky Hotel (site-3) in February $18^{th}-21^{st}$, 2008. The B[a]P concentration showed a value 0.54 fold, lower than the United Kingdom Expert Panel on Air Quality Standard (UK-EPAQS; i.e. 250 pg $m^{-3}$) at the top level. In contrast, the B[a]P concentrations exhibited, at the ground and middle level, values 1.50 and 1.43 times higher than the UK-EPAQS standard respectively. PAHs displayed a diurnal variation with maximums at night time because of the traffic rush hour coupled with lower nocturnal mixing layer, and the decreased wind speed, which consequently stabilized nocturnal boundary layer and thus enhanced the PAH contents around midnight. By applying Nielsen's technique, the estimated traffic contributions at Site-3 were higher than those of Site-1: about 10% and 22% for Method 1 and Method 2 respectively. These results reflect the more complicated emission sources of PAHs at ground level in comparison with those of higher altitudes. The average values of incremental individual lifetime cancer risk (ILCR) for all sampling sites fell within the range of $10^{-7}-10^{-6}$, being close to the acceptable risk level ($10^{-6}$) but much lower than the priority risk level ($10^{-4}$).

• 패션비즈니스
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• 제1권4호
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• pp.10-18
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• 1997

Sleeping is important for human being in that it has a great effect on their daily activities. Considering that an average adult sleeps seven to eight hours a third of our life is spent in bed. The present study intends to make consumers aware of the important of the bedding science and help the manufactures develop efficient, up-to-date beds. For these two purposes, consumers' recognitions and opinions on the features of the bedding were surveyed. In the study, a questionnaire consisting of various items on the features of the bedding was designed and distributed to consumers in 8 regions & Taegu in Korea to survey the patterns in which they buy, use, and maintain their bedding. The result of the study are as follows; Air conditioner is widely used popular because of hot weather in Taegu. People in Taegu mostly purchase their bedding from market, in every 5~6 years. The important point to be considered for bedding purchases were humidity absorption, air permeability, light weight in summer comforters, thermal insulation, flexibility, color figure design in winter comforters, humidity absorption, flexibility, color figure design in mats. As summer bedding, a sheet of single-layer quilt and rush mat were most popular which indicates climate of hot and humid weather in Taegu. Bedding uses in winter were in order a sheet of cotton, silk, wool quilt, and silk quilt showed high level in contrast to other areas. Dissatisfactions with summer quilts were humidity absorption, air permeability, heaviness and in winter quilts they were dissatisfied with thermal insulation, heaviness, flattening. In details about bedding managements, people in Taegu most frequently disinfected their bedding by sunlight in one month, and refinished every 5 years.

• 한국대기환경학회지
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• 제22권6호
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• pp.767-778
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• 2006

This study was carried out to evaluate the temporal variations of VOCs at an urban site, and to compare the concentrations of VOCs at an urban site in Daegu with those at a suburban site in Gyeongsan. Three hourly VOC samples in the ambient air were collected using a sequential tube sampler (STS 25, Perkin Elmer) throughout two weeks during May and July representing spring and summer seasons, respectively. The VOC concentrations were determined by an automatic thermal desorption apparatus with GC/MS analysis. A total of 12 VOCs of environmental concern were determined, which are chloroform, benzene, trichloroethylene, toluene, tetra-chloroethylene, ethylbenzene, m+p-xylenes, o-xylene, styrene, 1,3,5- and 1,2,4-trimethylbenzenes. Among 12 target VOCs, the most abundant compound appeared to be toluene, being followed by xylenes. The mean concentrations at the urbn site were 1.2 pub for benzene and 20.4 ppb for toluene (n=221) while the mean levels at the suburban site were 0.9 ppb and 4.3 ppb for benzene and toluene (n=96), respectively. The urban site concentrations were typically several-fold higher than those measured at the suburban site. It was found that general trends of VOC levels were significantly dependent on traffic conditions at the sampling site since VOC concentrations were at their maximum during rush hours, i.e. $9{\sim}12a.m$ and $6{\sim}9p.m$. Statistical investigations were conducted to investigate any significant relationships between VOC concentrations and affecting factors. Calculated correlation coefficients among VOCs were positively significant at a level of 0.05 in most cases. Increased concentrations of toluene in the urban site were estimated to reflect the effect of large industrial sources, mainly from textile industry.