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Tatsuya Sakurai,Miu Ito,Shinichi Hanayama 한국대기환경학회 2021 Asian Journal of Atmospheric Environment (AJAE) Vol.15 No.1
This study developed a database of emission inventories from ships around Japan using the activity data in the 2015 Japanese fiscal year. The emission of air pollutants from ships was estimated for fuel combustion in main engine, auxiliary engines, and boilers onboard. The ships’ operations for the emission estimation in the exhaust gas consist of ships in navigation, ships at anchor, and fishing boats. For the emission estimation regarding navigation ships, data from Automatic Identification System (AIS) received at the stationary stations on land in Japan were used in this study to calculate the activity. The emission amounts were compared between the sea (Seto Inland Sea (SIS) and Tokyo Bay) and prefectures surrounding those ocean areas. The ship emission ratios in total anthropogenic emissions including the land part reached SO2: 29%, PM: 40%, and NOx: 22% for the SIS area. In Tokyo Bay, the ship emission ratios in total reached SO2: 36%, PM: 28%, and NOx: 13%, and the emission intensities per unit area for SO2 and PM2.5 are approximately three times higher than those in the other regions, respectively. Therefore, the shipping traffic density is relatively higher compared to transportation on land, and the emission is condensed locally. Assuming that the 2020 global sulphur limit switched to a sulphur content of 0.50% m/m, SO2 emissions could be reduced to 24% in SIS and 22% in Tokyo Bay, sulphate emissions could be reduced to 23% in SIS and 21% in Tokyo Bay, and PM emissions could be reduced to 39% in SIS and 36% in Tokyo Bay. Therefore, the 2020 global sulphur limit should reduce the emission from ships around the Japan coastal area and improve the air quality in congested water areas such as SIS and Tokyo Bay.
Tatsuya SAKURAI,Takeru SUZUKI,Misato YOSHIOKA 한국대기환경학회 2018 Asian Journal of Atmospheric Environment (AJAE) Vol.12 No.1
This study aims to evaluate the performance of the Air Quality Model (AQM) for the seasonal and spatial distribution of the NH3 concentration in the atmosphere. To obtain observational data for the model validation, observations based on biweekly sampling have been conducted using passive samplers since April 2015 at multiple monitoring sites in the Tokyo metropolitan area. AQM, built based on WRF/CMAQ, was applied to predict the NH3 concentration observed from April 2015 to March 2016. The simulation domain includes the Kanto region, which is the most densely populated area in Japan. Because the area also contains large amount of livestock, especially in its northern part, the density of the NH3 emissions derived from human activities and agriculture there are estimated to be the highest in Japan. In the model validation, the model overestimated the observed NH3 concentration in the summer season and underestimated it in the winter season. In particular, the overestimation in the summer was remarkable at a rural site (Komae) in Tokyo. It was found that the overestimation at Komae was caused by the transportation of NH3 emitted in the northern part of the Kanto region during the night. It is suggested that the emission input used in this study overestimated the NH3 emission from human sources around the Tokyo suburbs and agricultural sources in the northern part of the Kanto region in the summer season. In addition, the current emission inventories might overestimate the difference of the agricultural NH3 emissions among seasons. Because the overestimation of NH3 in the summer causes an overestimation of NO3 - in PM2.5 in the AQM simulation, further investigation is necessary for the seasonal variation in the NH3 emissions.
Hiroshi Hayami,Yuta Iga,Syuichi Itahashi,Kazuhiko Miura,Tatsuhiro Mori,Tatsuya Sakurai 한국대기환경학회 2022 Asian Journal of Atmospheric Environment (AJAE) Vol.16 No.3
The global limit on the sulfur content of ship fuel was reduced from 3.50% to 0.50% in January 2020 to reduce ship emissions of SO2 and particulate matter. We conducted observational campaigns before and after the new global limit was introduced to detect changes in coastal air quality. We measured ambient concentrations of SO2 and CO2 ship plumes on shore with the sniffing method under the Kanmon Bridge over the Kanmon Straits between Honshu and Kyusyu Islands, Japan, for several weeks in August to September in 2019 and 2020. The fuel sulfur content (FSC) estimated from our measurements mainly varied from 0.50% to 3.00% in 2019, whereas the range narrowed to 0.10% to 0.40% in 2020, showing that all the ships complied. The mean FSC in 2020 was reduced to 16% of that in 2019, which was consistent with the reduction in the ambient SO2 concentration. Sakurai et al. (2021) estimated that after the 2020 global limit was brought in, SO2 emissions from ships were reduced to 24% of their previous values by assuming that all ships have a FSC of 0.50%. Our results indicate the 2020 global limit led to much greater reductions in SO2 emissions from ships than expected.
흉부(胸部) 경선질촬영(硬線質撮影)에 있어서 피폭선양(被曝線量)의 저감(低減)에 관(關)한 연구(硏究)
임태랑,석전유치,전전미향,앵정달야,김정웅,황종선,Hayashi, Taro,Ishida, Yuji,Maeda, Mika,Sakurai, Tatsuya,Kim, Chung-Woon,Hwang, Jong-Sun 대한방사선과학회 1991 방사선기술과학 Vol.14 No.2
Experiment was conducted on the image quality and exposure dose following replacement of $CaWO_4$ system screen BH-III and BX-III which have so far been used for high-voltage hard-radiation quality radiography, with rare earth system screen KO750, combined with high contrast film SRH, while additional filter was altered, Cu 0.8 mm+Al 1.4 mm(HVL : Al 8.8 mm), Cu 1.3 mm+Al 1.0 mm(HVL : Al 10.6 mm) and Cu 1.8 mm+Al 1.5 mm(HVL : Al 11.4 mm). AS a result, visual evaluation did not detect extreme changes in image quality under the respective condition(HVL : $Al\;8.8\;mm{\sim}Al\;11.4\;mm$). It was noted, however, that surface exposure dose declined with an increase in the thickness of the additional filter, as it was $18.9\;{\mu}Gy$ at HVL Al 8.8 mm, $17.5\;{\mu}Gy$ at Al 10.6 mm and $15.7\;{\mu}Gy$ at Al 11.4 mm. Considering the limited rating of X-ray equipment and wear of machinery, however, the range of $Cu\;1.3\;mm{\sim}1.8\;mm+Al\;1.0\;mm{\sim}1.5\;mm(1/16\;VL{\sim}1/32\;VL)$ seemed to be a limit.
김철희,장임석,김정수,Fan Meng,Mizuo Kajino,Hiromasa Ueda,Yuanhang Zhang,손혜영,Youjiang He,Jun Xu,Keiichi Sato,송창근,반수진,Tatsuya Sakurai,Zhiwei Han,Lei Duan,이석조,심상규,영선우,이태영 한국기상학회 2011 Asia-Pacific Journal of Atmospheric Sciences Vol.47 No.4
Three comprehensive acid deposition models were used to simulate the sulfur concentrations over northeast Asia over the period covering entire year of 2002, and discussed the aggregated uncertainties and discrepancies of the three models. The participating models are from the countries participating in the project of Longrange Transboundary Air Pollutants in Northeast Asia (LTP): China,Japan and Korea. The Eulerian Model-3/CMAQ (by China), Regional Air Quality Model (RAQM, by Japan), and Comprehensive Acid Deposition Model (CADM, by Korea) were employed by each country with common emissions data established by the administrative agencies of China, Japan and Korea. The episodic simulation results between 1 to 15, March 2002 are also presented, during which aircraft measurements were carried out over the Yellow sea. The episodic results show both a wide short-term variability in simulations against measurements, and maximum concentration differences of 3~5 times among the three models, requiring that further attention before confidence among the three models can be claimed for short-term simulations. However, the year-long cumulative simulations showed almost the same general features, with lower aggregated uncertainties between the three models, produced by the long term integration over northeast Asia.
흉부단층촬영시(胸部斷層撮影時) 피폭선량(被曝線量)의 저감(低減)에 관(關)한 연구(硏究)
반야유,이만구,임태랑,석전유치,전전미향,앵정달야,박영희,김창남,신동식,Lino, Yu,Lee, Man-Koo,Hayashi, Taro,Ishida, Yuji,Maeda, Mika,Sakurai, Tatsuya,Park, Yong-Hee,Kim, Chang-Nam,Shin, Tong-Sik 대한방사선과학회 1994 방사선기술과학 Vol.17 No.2
Tomographic examination requires several times of exposure usually, therefore, reduction of radiation dose per exposure without loss of image quality proves of great benefit to patient. We compared the exposure doses under the following experimental conditions, A and B. A is the combination of SRO 380(rare earth screen) and SRH(high contrast film) with additional Cu filters or without. B is the widely used combination which is BH-III and Cronex-4 without additional filter. As a result, comparing with the condition B, the condition A with additional filter of Cu 0.15 mm + Al 0.7 mm, Cu 0.4 mm+ Al 0.4 mm and Cu 0.8 mm showed better Image quality and lower surface dose, 44 %, 31 % and 24 % of the condition B, respectively.