• 설비공학논문집
• /
• 제16권4호
• /
• pp.324-331
• /
• 2004

Particle Image Velocimetry (PIV) measurements have been carried out to investigate the pulsatile flow characteristics in a triangular grooved channel. The results showed that a vortex was generated at the tip of the groove and flowed into the groove rotating inside during the acceleration phase of the main stream promoting the mixing of the fluid. Then, at the deceleration phase of the main stream, the vortex entrained fluid from the relatively slow moving main stream to grow bigger than the groove size. Finally the vortex was ejected to the main stream carrying the fluid away from the groove, resulting in the enhancement of mixing between the stagnant fluid in the groove and the main stream in the channel. It was found that the fluid mixing enhancement is maximized when the pulsatile period is the same as the time duration which the vortex takes to grow larger enough to fill the groove and to be ejected to the main stream.

• Membrane and Water Treatment
• /
• 제11권1호
• /
• pp.49-57
• /
• 2020

The effect of Combined Sewer Overflow on the river system was investigated throughout three preliminary field tests and three main ones. As a result of the study, Combined Sewer Overflow did not affect water qualities on the main stream since the concentration of the main stream did not significantly changed during rainfall events although the water quality of tributaries has rapidly deteriorated due to the influence of the Combined Sewer Overflow during rainfall events. The main cause of the result is that the flow rate of the tributaries is considerably lower than that of the main stream, so that the tributaries with deteriorated water quality during rainfall events did not significantly affect the quality of the actual main stream. Therefore, the water quality of the Kumho River is more affected by the wastewater treatment facilities that discharges water continuously to the main stream than pollutants from non-point pollution sources during rainfall events. As a result, managements for discharges from wastewater treatment facilities should be strengthened in order to improve the water quality of the river.

• 대한토목학회논문집
• /
• 제12권4_1호
• /
• pp.97-106
• /
• 1992

하천 수로망(水路網)의 수로길이와 본류(本流) 수로길이는 사용된 지형도(地形圖) 축척(縮尺)에 따라 각각 다른 값을 나타내며, 이와 같은 지형도상(地形圖上)의 수로길이는 Fractal로 간주할 수 있다. 수로망(水路網)의 하천길이와 본류(本流) 수로길이를 Horton 법칙을 적용함으로써 유역면적비(Ra)만의 함수로 나타내어, 수로망(水路網)의 하천길이에 관한 Fractal Dimension(D)와 본류(本流) 수로길이에 관한 Fractal Dimension(d)를 길이의 비(比)($R_L$)과 유역면적비(比)($R_a$)의 함수로 각각 유도하였다. 유도된 결과식을 금강수계내(錦江水系內) 산성(山城)유역의 수로망(水路網)에 적용하여 기(旣) 발표된 공식과 비교 검토하였으며, Fractal Dimension은 수로망(水路網)의 경우 지형도(地形圖) 축척(縮尺)이 클수록 2에 가까운 값을 나타낸 반면에, 본류(本流)수로의 경우는 1에 가까운 값을 나타내었다. 본 연구의 결과는 지형도(地形圖) 축척(縮尺)에 따르는 수로망(水路網)구성의 정량적(定量的) 분석에 도움이 되리라 생각된다.

• 한국물환경학회지
• /
• 제34권1호
• /
• pp.96-108
• /
• 2018

Large efforts have recently been made on research and development of sustainable and energy-efficient short-cut nitrogen removal processes owing to strong attention to the energy neutral/positive wastewater treatment system. Anaerobic ammonium oxidizing bacteria (anammox bacteria) have been highlighted since 1990's due to their unique advantages including 60% less energy consumption, nearly 100% reduction for carbon source requirement, and 80% less sludge production. Side-stream short-cut nitrogen removal using anammox bacteria and partial nitritation anammox (PN/A) has been well established, whereas substantial challenges remain to be addressed mainly due to undesired main-stream conditions for anammox bacteria. These include low temperature, low concentrations of ammonia, nitrite, free ammonia, free nitrous acid or a combination of those. In addition, an anammox side-stream nitrogen management is insufficient to reduce overall energy consumption for energy-neutral or energy positive water resource recovery facility (WRRF) and at the same time to comply with nitrogen discharge regulation. This implies the development of the successful main-stream anammox based technology will accelerate a conversion of current wastewater treatment plants to sustainable water and energy recovery facility. This study discusses the status of the research, key mechanisms & interactions of the protagonists in the main-stream PN/A, and control parameters and major challenges in process development.

• 한국환경복원기술학회지
• /
• 제9권3호
• /
• pp.39-50
• /
• 2006

In this study, the water quality investigated during 2002s to 2004s for Anyang river and its affluent that was based on biological and chemical methods as well as ecological index of each streams. The improving of water quality and the multiplicity of specious in the most streams except for Anyang, which was due to the improving of water quality and water resource. The seasonal dry states are completely disappeared, but water quality of Anyang main stream was classified as fifth grades water with BIP 8.51~10.00 and BOD 8.16~14.4mg/l in Anyang stream overall. And alpha-mesosaprobic in upper, mid parts and polysaprobic in down parts of Anyang main stream are appeared according to Saprobien system, respectively. The water supply of treated sewage is appeared that upgrading effects of water quality in Anyang main stream and affluents of Anyang city area, but the practical effects of "Saving Anyang River" could not gained because the water quality of other branches in upstream parts than upstream measuring point of Anyang main stream, Wanggok stream Sanbon stream in Gunpo and Eeiwang cities, was not improved.

• 한국습지학회지
• /
• 제11권1호
• /
• pp.65-73
• /
• 2009

황구지천과 청미천의 본류와 폐천에서 하도형태, 식물상 및 식생분포 특성을 분석하였다. 항공사진과 옛 지형도를 분석한 결과, 폐천은 제방축조에 의해 사행하도가 단절되어 형성된 것으로 나타났다. 전체 식물종수와 귀화식물 백분율은 본류가 폐천에 비해 높았다. 두 폐천에서 수생, 습생식물 종수의 백분율은 각각의 본류에서 보다 높았다. 주성분분석결과 폐천과 본류 사이의 식물상 구조는 황구지천이 청미천에 비해 비교적 유사하게 나타났다. 두 폐천에서 수생, 습생 식물 분포 면적비율은 각각의 본류에 비해 높았다. 두 폐천에서 우점식물은 정수식물인 줄이었다. 따라서 폐천의 식물상과 식생분포는 습생, 정수 생태계의 특성을 나타내었으며 경관수준에서 다양성을 제공하였다.

• 복식문화연구
• /
• 제12권3호
• /
• pp.327-338
• /
• 2004

This study was attempted to check period of a fashion cycle and to suggest its main-stream and sub-stream by analyzing the fashion trends presented in Vogue Korea between 1997 and 2002. A content analysis method was used to analyze 24 volumes. The result showed that the fashion trend of 1997's was a turning point from the simplicity, which was a trend up to 1996's, to the romanticism. The fashion trends of 2002 seemed to be also a turning point from the new-romanticism which was added the hippism to the romanticism continued from 1997, to the sporticism. The result confirmed that the main-stream of fashion theme have been continued for 5 years as a regular cycle system and could be repeated. It also verified that some sub-stream which was affected by social, cultural and political situation led the fashion changes. The results of this study could be expected to reflect not only fashion design, merchandising and marketing strategy but also consumer purchase behavior of the future.

• 환경위생공학
• /
• 제13권1호
• /
• pp.135-146
• /
• 1998

In this study, we investigated to measured concentration, seasonal characteristics and load quantity of volatile organic compounds(VOCs) for 11 sites in the main stream and 8 sites in the branch stream of Kumho river, during from October 1995 to April 1997. As a results, the small amount of volatile compounds, such as dichloromethane, chloroform, toluene, benzene, trichloroethene, tetrachloroethene, p-xylene and 1,3,5-trimethyl-benzene were detected from the main stream of Kumho river. Also detected to dichloromethene, chloroform, toluene, benzene, trichloroethene, tetrachloroethene, ethylbenzene, p-xylene, 1,3,5-trimethylbebzene and 1,2,4-trimethylbenzene in the branch stream, and dichloromerhane, chloroform and toluene were detected to all site of sampling. And seasonal variation of volatile organic compounds showed higher concentration in the July 1996 as a winter season than January 1997 as a summer season in most places. Also the load quantity of volatile organic compound at Gangchang site in the last downstream of Kumho river, was in order of chloroform > dichloromethane > toluene > trichloroethene.

• 한국환경과학회지
• /
• 제16권3호
• /
• pp.333-345
• /
• 2007

As analyzed the estimated values of the daily delivery loads from thirteen major side streams such as Naesung-river, Keumho-river, Hwang-river, Nam-river during five years (from 1999 to 2003), the daily BOD inflow into the main stream of Nakdong river in 2003 shows the highest quantity as 31.1 ton and the daily BOD inflows in 1999, 2000, 2001, and 2002 are 26.7 ton, 22.5 ton, 21.0 ton, 25.8 ton, respectively. The daily TN in-flow into the main stream of Nakdong river in 2003 shows also the highest quantity as 64.9 ton and the daily TN inflows in 1999, 2000, 2001, and 2002 are 55.19 ton, 46.27 ton, 39.5 ton, 53.38 ton, respectively. The daily TP inflow into the main stream of Nakdong river in 2003 shows the highest quantity as 2.70 ton likewise and the daily TP inflows in 1999, 2000, 2001, and 2002 are 2.17 ton, 1.87 ton, 1.60 ton, 2.10 ton, respectively The rate of BOD loads from each side main stream into the main stream of Nakdong river shows that the BOD loads of Keumho-river are the highest as the values range from 32.8 % (2002) ${\sim}$ 35.1 % (2003) and the BOD loads of Nam-river, Naesung-river, Hwang-river are high in the order named. The rate of TN loads to the main stream is also similar to the trend of BOD loads. The contribution of the TN loads of Geumho-river to the contamination of the main stream is also the highest having a range from 27.0 % (2002) to 28.8 % (1999) among the main side streams and the TN loads of Naesung-river, Nam-river, and Heachun-river are high in the order named. The rate of TP loads is quite different from the trend of BOD and TN loads. The TP rate of Keumho-river, however, is still the highest as ranging 58.6 % (2002) to 61.7 % (2003) and the river has the biggest portion (over 50%) of the entire pollution to the main stream of Nakdong river.

• 환경위생공학
• /
• 제19권3호
• /
• pp.40-51
• /
• 2004

Community structure of benthic macroinvertebrates in the water system of Anyang Stream was analyzed from August, 2002 to April, 2003. Species number of benthic macroinvertebrates was 78 species, 33 families, 11 orders, 5 classes in 3 phyla. They were collected 49 species at 1st survey, 51 species at End survey and 53 species at 3rd survey, respectively. Species numbers at each tributary were 43 species at the Wanggok Stream, 44 species at the Mokgam Stream, 33 species at the Ohjeon Stream and 26 species at the Hakeu Stream, while it was only 9 species at the Dangjeong Stream. Species number of the main course of Anyang Stream was 24 species. Dominant species of benthic macroinvertebrates at the Wanggok, Ohjeon and Hakeu Stream were Baetis fuscatus, Alainites muticus, Physa acuta and chironominae sp. They were mainly intermediate and tolerant species. Dominant species and subdominant species of the Dangjeong Stream were Limnodrilus socialis, Psychoda KUa and Telmatoscopus KUa as indicator species for severe sewage pollution. Dominant species at Geumjeong-dong and KUa bridge in the main course of Anyang Stream were Physa acuta, Limodrilus gotoi, Chironominae sp., Species diversity indices at the Mokgam Stream were $high(3.53\~4.28\;range)$ and those of the Hakeu, Wanggok and Ohjeon Stream were some what high$(2.00\~3.13\;and\;2.34\~3.10\;range)$. But, species diversity indices in the Dangjeon Stream were low$(1.36\~1.70\;range)$ too. and those of the main course of Anyang Stream were low$(0.86\~1.79\;range)$ too. Species richness indices in the Wanggok and Mokgam Stream were very high$(3.55\~4.02\;and\;2.96\~5.31\;range)$ and those of Geumjeong-dong and Kia bridge in the main course of Anyang Stream were low$(0.89\~1.98\;range)$. Stream bed and riparian bank of middle reach in the Wanggok Stream were good condition and water was clean. The Mokgam Stream had various microhabitats, good water weed area, hetero geneous substrates and etc.. And, stream bed in the Hakeu Stream was in good condition. So, above streams should be continuously in good ecological condition and useful area for citizens.