• Title/Summary/Keyword: Resuspension

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Estimation of Source Contribution of Particulate Matter in Taegu Area using Factor Analysis (다변량 통계분석법을 이용한 대구지역 부유분진의 오염원 기여도 추정)

  • 최성우;송형도
    • Journal of Environmental Health Sciences
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    • v.26 no.4
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    • pp.1-8
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    • 2000
  • The objective of this study was to identify the sources and to estimate the source contributions to the atmospheric TSP(total suspended particulate matter) and PM-10(particulate matter with aerodynamic diameters less than 10$\mu\textrm{m}$) concentration in Taegu area. A total of 84 samples was collected during the January to December 1999. TSP and PM-10 were collected on filters by portable air sampler, and heavy metals in TSP and PM-배 were analyzed by ICO(Inductively Coupled Plasma Spectrometery) after preliminary treatment. The results were follow as : First, annual average of TSP and PM-10 concentration was 123 and 69$\mu\textrm{g}$/㎥ respectively. The concentration of TSP and PM-10 were highest in winter season compared to other seasons. Second, the concentration of Al, Fe, Mn were higher in TSP than in PM-10, indicating that these heavy metals are generally associate with natural contributions. Third, metal combinations showed that a high correlation among concentrations of heavy metals were follows: As Al, Fe and Mn in TSP ; Ni, Cr, Cd and Pb in PM-10. Finally, Statistical analysis was performed using Principal Components Analysis(PCA) in order to find possible sources of the pollutants. The factor analysis was permitted to identify four major sources(soil/road dust resuspension, waste incineration, furl combustion, vehicular emission) in each fraction. These source accounted for at least 83, 85% of variance of TSP and PM-10 concentration in Taegu area.

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Modeling Sedimentation of Fine-grained Sediments in a Rectangular Basin (장방형 해분내의 세립 퇴적물 퇴적모형)

  • Hyo Jin Kang
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.3 no.1
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    • pp.38-44
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    • 1991
  • A simple box model was applied to the sedimentation of fine-grained sediments in a rectangular basin. Using the model explanation of the net depositional process of One-grained sediments in a small tide-dominated rocky embayment was possible by a careful evaluation of coefficients for erosion and deposition. For a basin with an inlet through which the exchange of suspended sediments occurs between open sea. the model shows that the time-averaged concentration of suspended sediments for a tidal cycle reaches a steady state initial abrupt change in concentration. During a tidal cycle deposition of sediments seems to occur when the magnitude of tidal currents is substantially low near the slack waters. Resuspension and erosion of bottom sediments take place near the peak of tidal currents. For a depositional basin. Gamagyang Bay, the duration and the maximum rate of deposition appear to be longer and higher than those of erosion. which accounts for the net deposition of fine-grained sediments. The time-averaged concentration of suspended sediment in the basin is slightly lower than that of the open water due to the net deposition. The instantaneous concentration of suspended sediments showed the maximum value about an hour before high water and the minimum about an hour after low water.

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Development of Estimation Equations for Solid Deposition in Sewer Systems (관거 내 고형물 퇴적량 산정식 개발)

  • Lee, Jae-Soo
    • Journal of Korea Water Resources Association
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    • v.40 no.5
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    • pp.409-418
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    • 2007
  • Combined sewer solid deposition during dry weather periods and their resuspension during wet weather periods has long been recognized as a major contributor to the first-flush phenomenon. Also, these deposition of sewer solids results in a loss of flow capacity that may restrict flow and cause a local flooding at urban area. In order to solve these problems, measurement of solid deposition for a given sewer system for extended period is needed but this task is very difficult and extremely expensive. This paper presents the development and applicability of estimation equations for solid deposition in sewer systems based on the solid deposition estimated using MOUSE model. As results, the comparison between estimated and measured solid deposition is difficult due to the absent of measured data, but the estimated values using developed equations show applicability compared with the results of MOUSE model and the estimation equations developed by the EPA.

Seasonal and Locational Concentrations of Particulate Air Pollutants in Indoor Air of Public Facilities in Taegu Area (대구지역 공중위생법 규제대상시설의 실내공기중 입자상 오염물질의 계절별 및 지점별 농도분포 특성)

  • 백성옥;송희봉
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.3
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    • pp.163-176
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    • 1998
  • In this study, airborne particle samples were obtained to determine the concentrations of particulate air pollutants in indoor and outdoor air of public facilities in Taegu area. Total of 12 public facilities, regulated by the Public Sanitary Law, were selected as sampling sites, which include three underground arcades, one railway and two bus terminals, three general hospitals, and three department stores. In each place, sampling was carried out seasonally during the period of October 1994 to July 1995, and four samples per each site per season were collected both indoors and outdoors simultaneously. After determination of suspended particulate matter (SPM) mass concentrations, the particle samples were divided into two parts for subsequent chemical analysis: one for the analysis of trace elements and the other for water soluble ions. Seasonal levels of SPM appeared to be the highest in spring and the lowest in summer both indoors and outdoors, while locational variations of highest in statioyterminals, and lowest in department stores . SPM concentrations indoors and outdoors did not show any significant differences each other in most places . However, there were significant correlations between indoor and outdoor levels of SPM and other chemical species . These results indicates that indoor SPM levels are likely to be significantly affected by outdoor sources in many places. The most significant source of SPM was estimated to be the resuspension of soil/road dust both indoors and outdoors . The concentrations of toxic heavy metals (Pb, Cd, Cr, Cu) in underground arcades appeared to be very much lower than the established air quality guidelines for underground environments. In addition, it is likely that micro-environmental parameters such as temperature, humidity, and air velocity, play a less significant role than outdoor air quality as a factor affecting the levels of particulate pollutants in indoor environments of public facilities in Taegu area.

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Treatment Efficiency of a Subsurface-Flow Wetland System Constructed on Floodplain (고수부지를 이용한 여과습지의 수질정화 초기처리)

  • Yang, Hongmo
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.4 no.4
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    • pp.56-63
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    • 2001
  • This paper presents treatment efficiency and plant growth of a subsurface-flow constructed wetland system (23 m in length, 6.5 m in width, 0.65 m in depth) over one year after its establishment on floodplain of a stream in June 2000. An upper layer of 10 cm in depth was filled with course sand and the main biological layer of 50 cm depth with crushed stone with 8 - 15 mm in diameter. The system was planted with common reeds (Phragmites australis) grown on pots. Effluent discharged from a secondary-level treatment plant was funneled into it. Reed stems emerging in April 2001 grew up to 145.9cm until July 2001. The number of reed stems in July 2001 increased by about 11 times compared with that just after planting. The system was inundated seven times by storms over the monitoring period. Reeds were slightly bent after flooding, however they returned to almost upright standing in a couple of weeks. Small portion of inside slope of berm was eroded and the system surface had a sedimentation of 2 - 3 mm in depth. The average removal rates for SS, $BOD_5$, T-N and T-P was 73%, 70%, 53%, and 72%, respectively. The purification efficiencies for SS and $BOD_5$ were fairly good. The reduction rates for T-N was relatively low for the period of late fall through winter until early spring due to lower water temperature which retarded microbial nitrification and denitrification mechanisms. Reduction in the concentration of T-P during fall and winter was relatively higher than that during spring. Leach of phosphorous from plant litters lying on system surface and slight resuspension of precipitated phosphorous in substrates resulted in lower reduction for T-P in spring.

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Seaweed Community of the Subtidal Rocky Habitats along the Coast of Geumo Archipelago in the Central South Sea of Korea (한국 남해중부 금오열도 연안 암반 조하대 해조군집의 구조)

  • Kang, Rae-Seon;Kim, Jong-Man
    • ALGAE
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    • v.19 no.4
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    • pp.339-347
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    • 2004
  • Seaweed community of the sub tidal rocky habitats along the coast of Geumo Archipelago in the central South Sea of Korea is described. This area is characterized by archipelago in which islets are separated by shallow bottom sediments (primary, muddy sand), and turbidity is generally high due to the resuspension of bottom sediments. The hard substrata available for algal attachment are limited to less than 10 m in depth. Thirty sites were randomly chosen along the coast from August 2003 to September 2003 and a 50 m long transect was established at each site. The transect began at a depth of 1 m and ended at the depth of 9 m. The percent cover of all species other than crustose coralline algae was estimated at 2 m depth intervals along the transect using a 0.25 m$^2$ PVC quadrat with 25 squares. Thirty-six species were identified including 6 Chlorophyta, 10 Phaeophyta and 20 Rhodophyta. Species with more than 5% mean bottom cover were Gelidium amansii, Corallina pilulifera, Amphiroa dilatata and Carpopeltis cornea, which formed dense turf-forming algal assemblages at 1-5 m depth. At all sites except S11-S15 located in the western coast of Sorido, bottom covers of seaweed species at the depth deeper than 7 m were less than 6%. The lower limit of algal assemblages was 9 m in depth. We speculate that the limited water clarity and vertical extent of hard substrata available for the settlement of seaweed species are the direct cause of reducing the diversity, abundance and distributional extent of algal assemblages in the area.

Surgical Treatment of Aortic Aneurysm - Review of 37 cases between 1984 and 1987 - (대동맥류의 외과적 치료 -37례 보고 (1984-1987) -)

  • Won, Yong-Soon;Ahn, Hyuk
    • Journal of Chest Surgery
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    • v.21 no.3
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    • pp.488-496
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    • 1988
  • Thirty-seven patients of aortic aneurysm underwent operations during January 1984 December 1987 at our hospital. Twenty-six patients had aneurysms involving ascending aorta, three patients had aneurysms involving both ascending aorta and abdominal aorta. and eleven patients had aneurysms involving descending thoracic or abdominal aorta. Among the patients who had aneurysms involving ascending aorta, annuloaortic ectasia with aortic regurgitation were thirteen and all of these underwent ascending aorta graft replacement + AVR with composite graft. The patients who had aortic regurgitation due to ascending aortic dissection were three and all of these underwent intraluminal ringed graft insertion at ascending aorta + aortic valve resuspension. Intraluminal ringed graft insertion was safe, simple, and fast method in the operation for aortic aneurysm. Eleven patients were underwent this operation and the results were good. Major causes of death of the patients who underwent aortic aneurysm operation are underlying cardiovascular diseases or delayed rupture of the aneurysm or complications related newly appeared aneurysm. Among our patients, dissection progressions were appeared in two but neither severe nor complicated. And no patient died from delayed rupture of aneurysm or complications related newly appeared aneurysm. All patients were followed up via OPD and were controlled hypertension or heart failure if present. Operative mortality is 18.9\ulcornera in all, 23% in patients who had aneurysms involving ascending aorta and 7.6` who had aneurysms involving descending thoracic or abdominal aorta. Comparing with other reports, our operative mortality is still high but improved steadily. So we recommend aggressive surgical management of the aortic aneurysm.

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Operative treatment of aortic dissections - Experience with 27 patients over a 5-year period - (대동맥 박리증의 수술요법 -27례의 수술환자를 대상으로 한 5 년간의 성적-)

  • Kim, Jhin-Gook;Ahn, Hyuk
    • Journal of Chest Surgery
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    • v.21 no.3
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    • pp.497-509
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    • 1988
  • Current therapy of aortic dissections remains unstandardized because of the relative rarity of these catastrophic events and conflicting reported results of various therapeutic strategies. Hence, we reviewed our current results and planned to purify our method of interpretation of results and so, to standardize therapeutic managements. This study comprised unselected, consecutive 27 patients with aortic dissections who were operated at Seoul National University Hospital from Jan 1983 to March 1988. The results from analysis of their preoperative, operative and postoperative finding were as follows: 1] 7 patients had acute type A, 14 had chronic type A, 4 had acute type B, and 2 had chronic type B. 2] The causes of dissections were unclear, but 8 patients had Marfan`s syndromes, 2 had previous operative histories on cardiovascular systems and 2 had congenital heart diseases. 3] Multiple preoperative variables were found to correlate significantly with operative mortality and complications. The prevalences of such preoperative major complicating factors were significantly more frequent in acute than chronic [P < 0.05] and type A than type B [P < 0.01]. 4] Operations were performed according to the type of the dissections and whether it was acute or chronic. Usually dacron tube graft replacements were performed[25/26]. Intraluminal sutureless graft replacement was performed in 11 patients. Of the 14 patients with combined aortic regurgitation, concomitant aortic valve resuspension in 4, seperative aortic valve replacement in 1, and aortic valve replacement with coronary reimplantation were performed in 9 patients. 2 patients had concomitant arch vessel managements. 5] Over-all operative mortality rate was 33% and 54% for acute type A, 25% for acute type B, 29% for chronic type A, 0% for chronic type B respectively. The main causes of operative mortality were cardiovascular complications [mainly CPB-weaning failure] in acute cases and hemorrhagic complications in chronic cases.

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The Effect of Physical Design Parameters on the Constructed Wetland Performance (물리적 설계인자가 인공습지의 처리효율에 미치는 영향)

  • Ham Jong-Hwa;Yoon Chun G.;Koo Won-Seok;Kim Hyung-Chul;Shin Hyum-Bhum
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.5
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    • pp.87-97
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    • 2005
  • The field scale experiment was performed to examine the effect of physical design parameters on the constructed wetland performance and recommend the feasible design of constructed wetland in Korean polder areas. Four sets (each set of 0.85 ha) of wetland (0.8 ha) and pond (0.08 ha) systems were used. Two different wetland systems, a wetland-pond system and a pond-wetland system, were studied to examine the effect of wetland and pond configuration. And two different length-to-width ratios were used, 2: 1 and 0.8: 1, to examine the effect of aspect ratio. A pond-wetland system was more preferable than a wetland-pond system, and also requires a smaller area than a wetland-pond system or a wetland system to reduce T-P. There was no difference in effluent concentration between the 2:1 system and the 0.8:1 system. Although the linear velocity of the 2:1 aspect was higher than the 0.8:1 aspect, resuspension was not a factor in this study due to a very low linear velocity. From this study and other literature review, it was found that design method of paddy rice field could be applied and expanded to the design of constructed wetland in Korea. Further investigation for the detailed design parameters of constructed wetland needs be continued for design method of paddy rice to be applied in full scale.

The Evaluation of Water Quality in Coastal Sea of Saemangeum by Chemical Environmental factors (새만금 하구역의 이화학적 환경요인에 따른 수질 평가)

  • Kim, Jae-Ok;Kim, Won-Jang;Jo, Kuk-Hyun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.5
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    • pp.57-65
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    • 2007
  • The objective of this study was to evaluate chemical water quality by hourly monitoring(25hr) of Saemangeum esturary. For this study, we selected 2 sites like a Mangyong Bridge(St. 6) and Dongjin Bridge(St. 7). Inflow of salt water was not detected during low tide(maximum 553, 508cm) of all stations, while the salinity rises were detected in spring tide(750cm). When 602m of maximum tide was reached, salinity concentration was increased at St. 7, while there was no change in St. 6. Therefore, We know that salinity variation is greatly influenced by tide height at survey site. Also, significant variance of salinity(p<0.05) was found between St. 6 and St. 7 because dike construction made the flood tide move into the Dongjin river. Total suspened solids(TSS) concentration was increased because of the river runoff at St. 6, and also the turbulance and resuspension according to salt intrusion at St. 7. During the high tide, the water discharge from the sea seemed to dilute the nutrient but to elevate TSS concentration in St. 7. Silicate and nitrate concentrations in the studied site were decreased by the mixing of sea water, whereas the evident trend of phosphate concentration was not found. This result can be explained by the phosphorus condition. Phosphorus exists inactive when it is affected by hydrated iron and adsorbed onto suspended matters. Compared to the environmental conditions of the St. 6 and St. 7, physical factors such as temperature, dissolved oxygen and TSS have statistically no significant difference(p<0.001), but nutrient concentrations were higher at St. 6 than St. 7. It could be suggested from these results that it is important to control the discharge of fresh water by sewage treatment plants located in St. 6 for water quality management.