• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 제5회 압출 및 인발가공 심포지엄
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• pp.23-32
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• 2002

The torsional forward extrusion is the process that is executed by punch travel and die rotation. The advantages of having the die rotation on this process are that forming load can be reduced and optimal die angle can be increased. This provides a possibility to extrude cold-worded material where a large extrusion force and die angle are required. Also, this process can improve the material properties owing to the high deformation and uniform strain distribution. The forming load and optimal die angle of this process are determined by the upper bound analysis using stream function and the optimization technique. To verify the theoretical result, we have carried out experiments and FE simulations using DEFORM3D.

• 산업기술연구
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• 제18권
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• pp.399-404
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• 1998

The purposes of this research were constructed the database, based on graphing the present water pollution in Han-river due to livestock wastewater(LSW). The LSW was below 1% in respect to quantity but about 7% in respect to pollutants loading in overall Han-river. The ratio of untreated LSW is 18% to 28%, which was higher compared to the municipal and industrial wastewater. In other words, LSW was about 0.05 times of municipal wastewater in respects to quantity but 2 times in respect to the ratio of untreated wastewater. So, it was necessary for treating LSW. The pollutants loading due to livestock wastewater of the South Han-river, North Han-river and main stream were 19.7%, 19.4% and 4.0%, respectively. This was about 7% in overall Han-river. We separated the Han-river into upper, mid and down stream. As a result, we found that the livestock wastewater is the main water pollution source of upper Han-river.

• 한국환경과학회지
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• 제2권4호
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• pp.291-297
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• 1993

The COD values and chloride ion concentrations of the Taewha river flowing through Ulsan area were determined along the main stream and the relationships between CODs and chloride ion concentrations were described. The results showed that the middle-upper stream and downstream of the Taewha river were polluted deeply with municipal sewage and self-purification occured in the middle-downstream of the river. When domestic sewage is a main source of pollutants, and is especially the only source of chloride in the stream water, the ratio of COD/[$\textrm{Cl}^{-}$] will be utilizable as a measure of self-purification of the stream.

• The Korean Journal of Ecology
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• 제14권2호
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• pp.195-210
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• 1991

The primary succession of the pebble area in gye-bang chon, an upper stream bank of north han river, was investigated by belt transect method from July to October 1990. The stsges of bare area, herbaceous pioneer, perenial herb, woody plants and pine stand were recognized from stream bank to inland. The change of the coverage in herbaceous plants increased with developing sueccessional sere but decreaser with increment of woody plants. The species sequence cyrves vs. relative coverage were geometric in pioneer stage and graduaiiy changed to lognormal y\type as the development of forest. The species diversity was highest during then woody plants stage, probably it would to be the edge effect. The soil properties were not noticeable difference between stream side and inland side. It seems that the vegetational developement was not enough to affect soil accumulation.

• 한국지형학회지
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• 제25권4호
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• pp.1-19
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• 2018

This study tries to identify distributional characteristics of stream incision rates at 23 points in the northern part of the Taebaek Mountains. Soyang-gang, Naerin-cheon, Odae-cheon, Dong-gang and upper reaches of Okdong-cheon Rivers closed to the Range show higher incision rates and the rates clearly decrease with distance from the Range. Therefore, the incision process in the northern part of the Range has been greatly influenced by uplift around the Range, and the Sobaek Mountain Range seem to play a role in the incision process. Limestone areas show lower incision rates due to degradation of terrace surface by dissolution. This study suggests that local hydrological, geological and geomorphological conditions can be regarded as an important factor in stream incision rates, although stream incision rates are greatly influenced by regional uplift.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.61-71
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• 2016

Visual MODFLOW was used for quantifying stream-aquifer interactions caused by seasonal groundwater pumping. A hypothetical conceptual model was assumed to represent a stream-aquifer system commonly found in Korea. The model considered a two-layered aquifer with the upper alluvium and the lower bedrock and a stream showing seasonal water level fluctuations. Our results show that seasonal variation of the stream depletion rate (SDR) as well as the groundwater depletion depends on the stream depletion factor (SDF), which is determined by aquifer parameters and the distance from the pumping well to the stream. For pumping wells with large SDF, groundwater was considerably depleted for a long time of years and the streamflow decreased throughout the whole year. The impacts of return flow were also examined by recalculating SDR with an assumed ratio of immediate irrigation return flow to the stream. Return flow over 50% of pumping rate could increase the streamflow during the period of seasonal pumping. The model also showed that SDR was affected by both the conductance between the aquifer and the stream bed and screen depths of the pumping well. Our results can be used for preliminary assessment of water budget analysis aimed to plan an integrated management of water resources in riparian areas threatened by heavy pumping.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1996년도 한국생물과학협회 국제학술대회
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• pp.113.2-113
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• 1996

No Abstract, See Full Text

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2020년도 정기학술대회 발표논문집
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• pp.167-167
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• 2020

• 한국지반환경공학회 논문집
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• 제9권7호
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• pp.5-11
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• 2008

본 연구는 청주시 인근의 미호천에서의 프탈레이트의 정성적 특성에 관한 것이다. 프탈레이트 중 DEHP와 DnBP가 가장 많이 사용되어 지고 있다. 미호천 상류와 하류에서 하천수에 함유된 DEHP의 농도는 각각 $12-18{\mu}g/{\ell}$, $11-21{\mu}g/{\ell}$이었다. 또한 이 지역의 퇴적물에서도 DEHP의 농도는 $0.07-0.82{\mu}g/g$(dry), $0.06-0.92{\mu}g/g$(dry), DnBP의 농도는 $0.04-0.25{\mu}g/g$(dry), $0.08-0.34{\mu}g/g$(dry)로 각각 조사 되었다. 공단지역으로부터 유입되는 작은 하천의 하천수에 함유된 DEHP와 DnBP의 농도는 각각 $13-28{\mu}g/{\ell}$, $2-8{\mu}g/{\ell}$이었으며, 퇴적물에서의 농도는 각각 $0.12-0.7{\mu}g/g$(dry), $0.17-2.16{\mu}g/g$(dry)이었다. 미호천과 미호천에 유입되고 있는 하수처리 방류수와 공단천의 프탈레이트 농도는 세계의 다른 지역보다 낮은 수치를 보이고 있다.

• 대한환경공학회지
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• 제35권2호
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• pp.94-100
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• 2013

본 연구에서는 합천댐 상류수계의 수질개선 및 수자원관리를 위한 기초자료로 활용하고자 2007년 1월에서 2010년 1월까지 황강본류 3개 지점과 지류 11개 지점을 선정하여 수질 및 유량조사를 실시하였으며, 이를 바탕으로 황강수질에 미치는 영향을 조사하였다. 본류 3개 지점 및 지류 11개 지점의 유량은 우기기간인 6월~9월 사이에 증가하여 건기기간인 가을과 겨울 사이에 지속적으로 감소하였다. 본류 3개 지점의 분석항목간 상관성은 $BOD_5$와 $COD_{Mn}$, $BOD_5$와 T-P 및 $COD_{Mn}$와 SS의 상관성이 각각 높은 것으로 나타났다. Chl-a와 수온은 (-)의 상관성을 보였으며, $BOD_5$와 $COD_{Mn}$는 (+)의 상관성을 보였다. 본류 3개 지점에서 N/P비율은 16이상으로 인이 제한영양염으로 작용하는 것을 알 수 있다.