• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.369-376
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• 2010

A novel or canal-type continuous removal of organic matter (C-CROM) with combined freshwater bivalves (Unio douglasiae and Anodonta woodiana) was developed to improve the water quality (IWQ) of eutrophic reservoirs. The first experiment was performed for 12 days to measure the IWQ using 256 individuals of combined bivalves (ca. 7:3), at the same density that distributed in the collection stream. The second experiment was conducted to evaluate the efficacy of IWQ with the addition of each 30% of two mussels for 14 days. Results indicated that a novel C-CROM significantly decreased suspended solids, chlorophyll-$\alpha$, transparency, total nitrogen and phosphorus, and increased ammonium and biodeposition (t-test, P<0.001 for all), while other dissolved inorganic nutrients such as $NO_2$, $NO_3$, and SRP did not change (t-test, P>0.5). Daily IWQ performances of C-CROM with combined mussels was about two times higher to the previous studies using single species where less suspended inorganic nutrients were released except for ammonia. Collectively, a C-CROM is more strategic to the water quality improvement of eutrophic lake.

• Journal of Life Science
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• v.17 no.5 s.85
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• pp.634-640
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• 2007

Our previous study suggested that n-3 fatty acid deficiency was associated with significantly reduced spatial learning as assessed by Morris water maze test. Here we investigated an effect of n-3 fatty acid deficiency on rat brain, retina and serum fatty acyl compositions at 15 wks age using a first generational artificial rearing technique. Newborn Rat pups were separated on day 2 and assigned to two artificial rearing groups or a dam-reared control group. Pups were hand fed artificial milk via custom-designed nursing bottles containing either 0.02%(n-3 Deficient) or 3.1% (n-3 Adequate) of total fatty acids as a-linolenic acid(LNA). At day 21, rats were weaned to either n-3 deficient or n-3 adequate pelleted diets and fatty acid compositions of brain, retina and liver were analyzed at 15 wks age. Brain docosahexaenoic acid(DHA) was lower(58% and 61%, P<0.05) in n-3 deficient in comparison to n-3 adequate and dam-reared groups, receptively, while brain docosapentaenoic acid(DPAn-6) was increased in the n-3 deficient group. In retina and serum fatty acid compositions, the decreased precentage of DHA and increased precentage of DPAn-6 were observed. These results suggested that artificial rearing method can be used to produce n-3 fatty acid deficiency in the first generation and that adequate brain DHA levels are required for optimal brain function.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.879-883
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• 2005

우리나라는 하천유역의 도시화 추세 속에 불투수층의 증가로 빗물의 일시 유출로 인한 홍수발생으로 많은 인명과 재산피해가 발생하고 있어 방재적 차원에서의 수자원관리가 시급한 실정이다. 또한, 초기 빗물과 합류식 하수도의 월류수에 의한 하천, 호소, 및 습지의 수질오염문제도 많이 발생하고 있다. 이러한 문제를 해결하기 위하여 콘크리트로 제작된 PC 지하식 빗물저류시설로서 상부의 공간은 공원, 운동장, 주차장 등 다양하게 이용하면서 방재와 치수를 가능케 할 수 있다. 또한, PC 콘크리트 빗물저류조는 현장 타설이 아닌 PC콘크리트 블록을 현장에서 조립하여 시공기간이 대폭적으로 단축되고, 작업환경 및 주변환경을 개선시킬 수 있다. 또한, 지하수의 보전, 회복을 위한 빗물저류 침투 시설 역할도 수행하여 비상용수를 확보하고 여름철 홍수 시 빗물을 가두어 재해를 방지하는 등의 다목적 시설로 활용된다. 지하 매립형 빗물저류조는 기존의 암거설계기준을 참조하여 일본의 내진설계 기준을 반영하였으며, 고강도 콘크리트를 사용하여 강도 또한 뛰어나다. 그리고 시공이 간편하고 공기의 단축에 탁월한 효과를 나타내며, 빗물저류조 설치는 다음과 같은 특징이 있다. 1. 지하저류형 빗물저류조 시설로 설계되어 토지의 효과적인 이용이 기대된다. 2. 공사기간이 짧아 경제적이다. 3. 안정된 구조체이다. 4. 부지의 형태에 맞춘 시공이 가능하다. 5. 소규모에서 대규모의 유수지까지 광범위하게 대응이 가능하다. 6. 방재역할 수행 및 빗물이용의 역할을 담당할 수 있다. 7. 불투수층이 증가하고 있는 도시지역에서 적극 활용가능하다.로 판단된다.한 예비방류의 시행과 강우종료 후에도 이수용량에는 손실이 없는 저수지의 관리방안의 지침이 되는데 효율적이라 판단되었다. 방법을 개발하여 개선시킬 필요성이 있다.>$4.3\%$로 가장 근접한 결과를 나타내었으며, 총 유출량에서도 각각 $7.8\%,\;13.2\%$의 오차율을 가지는 것으로 분석되어 타 모형에 비해 실유량과의 차가 가장 적은 것으로 모의되었다. 향후 도시유출을 모의하는 데 가장 근사한 유출량을 산정할 수 있는 근거가 될 것이며, 도시재해 저감대책을 수립하는데 기여할 수 있을 것이라 판단된다.로 판단되는 대안들을 제시하는 예비타당성(Prefeasibility) 계획을 수립하였다. 이렇게 제시된 계획은 향후 과학적인 분석(세부평가방법)을 통해 대안을 평가하고 구체적인 타당성(feasibility) 계획을 수립하는데 토대가 될 것이다.{0.11R(mm)}(r^2=0.69)$로 나타났다. 이는 토양의 투수특성에 따라 강우량 증가에 비례하여 점증하는 침투수와 구분되는 현상이었다. 경사와 토양이 같은 조건에서 나지의 경우 역시 $Ro_{B10}(mm)=20.3e^{0.08R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.198-212
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• 2002

A numerical variation and abnormalities were studied on egg bags and embryos of Korean salamander, Hynobius leechii from agricultural habitat. The teratogenic and toxic effects of fungicide benomyl were also investigated with early embryos from non-agricultural habitat. We collected 144 egg bags from agricultural region, and 3418 of early embryos were contained. The lengths of egg bags were varied from 10 to 23 cm and the most frequent length was 19 cm. The number of embryos was varied from 7 to 43, and the most frequent range was 22 to 26. Spontaneous abnormalities were occurred in 406 embryos among 116 egg bags, and 24 kinds of external abnormalities were found. Individuals showing severe external defect were histologically studied and they showed optic dyspalsia, thyroid carcinoma, somatic muscular dysplasia, partial biaxial structure, decrease of red blood cells in the heart, cephalic degeneration and intestinal dysplasia. 385 embryos from non-agricultural region were exposed to 200 nM${\sim}$ 1 ${\mu}$M of benomyl at blastula or gastrula for 12 days. All embryo were dead in the concentration of 1 ${\mu}$M (LD$_{100}$) and 75% of embryos were dead in 800nM of benomyl. Speciflc effect due to benomyl was acrania or cephalic dysplasia and this restult suggests that the benomyl inhibit stongly to the development of neural tissue. These abnormal developments may be caused by antimitotic action, inhibition of tubulin complex, destruction of microtubule, inhibitions of neurulation and closing of neural fold, and by the inhibition of the movement of neural crest cells.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.327-341
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• 2021

The riparian eco-belt is an efficient technique that can reduce non-point pollution sources in the basin and improve ecological connectivity and health. In Korea, a legal system for the construction and management of riparian eco-belts is in operation. However, it is currently excluded that rivers and floodplains in dam reservoir that are advantageous for buffer functions such as control of non-point pollutants and ecological habitats. Accordingly, this study presented and analyzed a plan to select a site for an integrated riparian ecol-belt that comprehensively evaluates the water quality and ecosystem characteristics of each dam floodplain and riparian zone for the Daecheong Dam basin in Geum River watershed. First, the Daecheong Dam basin was divided into 138 sub-basin with GIS, and the riparian zone adjacent to the dam floodplain was analyzed. Sixteen evaluation factors related to the ecosystem and water quality impact that affect the selection of integrated riparian eco-belt were decided, and weights for the importance of each factor were set through AHP analysis. The priority of site suitability was derived by conducting an integrated evaluation by applying weights to sub-basin by floodplains and riparian zone factors. In order to determine whether the sites derived through GIS site analysis are sutiable for actual implementation, five sites were inspected according to three factors: land use, pollution sources, and ecological connectivity. As a result, it was confirmed that all sites were appropriate to apply integrated riparian ecol-belt. It is judged that the riparian eco-belt site analysis technique proposed through this study can be applied as a useful tool when establishing an integrated riparian zone management policy in the future. However, it might be necessary to experiment various evaluation factors and weights for each item according to the characteristics and issues of each dam. Additional research need to be conducted on elaborated conservation and restoration strategies considering the Green-Blue Network aspect, evaluation of ecosystem services, and interconnection between related laws and policy and its improvements.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1944-1947
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• 2008

강우기에 하천 유역에서의 탁수 발생은 대상 지역의 토양, 토지 이용형태와 식생 분포, 강우의 강도, 토지의 경사 등에 따라 큰 영향을 받게 된다. 본 연구에는 토지의 이용형태에 따른 강우 시 탁수 발생량을 평가하고자 용담댐 유역의 탁수 발생특성 조사를 실시하였다. 2005년의 조사지점은 유역면적이 가장 작은 주자천 유역과 구량천, 금강본류를 대상으로 하였다. 구량천과 금강본류는 용담댐 유역을 구성하는 가장 큰 두 소유역이며 다를 지역에 비해 오염원이 많아 용담댐수질에 많은 영향을 주는 하천이다. 현장조사는 6월 27일부터 7월 3일 까지 실시하였다. 2007년 조사 대상 지역은 주자천 유역의 주천교 지점과 금강본류 유역의 월곡교 지점을 선정하였다. 현장조사는 6월21${\sim}$22일, 9월14${\sim}$15일 2회에 걸쳐 실시하였으며 시간별 현장 탁도 측정 및 시료 채취를 통한 분석을 병행하였다. 2005년에 실시한 조사결과 오염원이 많고 유역이 넓은 천천은 7월 1일에 유입량이 최대로 348.16CMS였으며, 그날 탁도는 오후 2시 10분조사시에 최대 2060NTU를 나타냈다. 구량천은 같은날 조사를 실시하여 유량은 최대 200.33CMS였고, 최대 탁도는 763NTU를 나타냈다. 반면 주자천에서는 최대 탁도가 98.4NTU를 나타내 가장 탁도가 높은 금강본류와는 약 13배의 차이를 나타냈다. 2007년 1차 조사는 6월 21${\sim}$22일에 걸쳐 이루어 졌다. 주천교 지점은 시간최대 강우 17mm가 발생한 시점에 최대 92NTU의 탁도를 나타내었고 그 이후 감소하여 20NTU이하의 탁도를 유지하였다. 반면, 월곡교 지점은 시간최대 23mm의 강우가 발생하였고, 최대 탁도는 3,610NTU에 도달하였으며 1,000NTU이상의 고탁도가 6시간 이상 유지된 후, 시간이 지남에 따라 점차 감소하였다. 이러한 결과는 미개발지역인 주천교 지점의 경우 강우에 의한 탁수 발생이 상대적으로 적음을 보여주고 있으며 월곡교 지점과 같이 개발로 인해 노출된 토양의 경우 강우에 의해 쉽게 침식이 일어나 고탁도의 탁수를 발생시킴을 보여준다. 그러나 주천교지점에서 2005년에 조사한 자료와 비교해 보면 2007년이 적은 강우임에도 불구하고 탁도는 높게 나타난 결과를 나타내고 있으며 이는 토지이용의 고도화에 따른 영향으로 판단되었다. 연구 결과 유역내에서 탁수 발생은 같은 강도의 강우에 있어서 큰 차이를 보이고 있음을 확인할 수 있었다. 따라서 강우기에 저수지에서의 탁수 문제의 해결을 위해서는 상류 유역의 탁수 발생원 관리가 중요함을 보여주고 있으며, 토지 이용 형태에 따른 토양 침식 방지 대책이 강우기의 댐 내 탁도 문제를 개선할 수 있는 중요한 방안으로 판단된다.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.61-67
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• 2008

This study was conducted to evaluate filtering rate (FR) and pseudofeces production (PFP) of a freshwater filter-feeding bivalve, Unio douglasiae, on a toxic cyanobacterium (Microcystis aeruginosa). The experiments were conducted under the various conditions of water temperature $(5{\sim}35^{\circ}C)$, mussel size $(5.6{\sim}13.3cm)$ and food con centrations $(49{\sim}491{\mu}g\;Chl-{\alpha}L^{-1})$. Among the applied temperature, the maximum FR $(0.41L\;gAFDW^{-1}hr^{-1})$ and PFP (0.47mg $gAFDW^{-1}hr^{-1}$) were observed at 15 and $25^{\circ}C$, respectively. Both weight-based FR and PFP were not correlated with the mussel size, and the values lied in a limited range with some degree of variation. Likewise, no significant relations between FR and PFP was observed in the mussel size. The FR values were negatively correlated with food concentration, while PFP showed positive correlation. Among the applied food concentrations, the maximum FR (0.34L $gAFDW^{-1}hr^{-1}$) and PFP (0.06mg $gAFDW^{-1}hr^{-1}$) appeared in $113{\mu}g\;Chl-{\alpha}L^{-1}$ and $491{\mu}g\;Chl-{\alpha}L^{-1}$, respectively. These results indicate that the grazing of Unio douglasiae are affected by various parameters, and it may be applied as an effective biofilter to inhibit Microcystis bloom under appropriate application. However, further studies on the fate of excreted pseudofeces are needed to understand their possibility of stimulating nuisant algal growth.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.1 s.4
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• pp.135-141
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• 2002

Both non-linear damping values of the deep and shallow crustal materials and seismic source parameters are found from the observed near-field seismic ground motions at the South-eastern Korean Peninsula. The non-linear numerical algorithm applied in this study is Levenberg-Marquadet method. All the 25 sets of horizontal ground motions (east-west and north-south components at each seismic station) from 3 events (micro to macro scale) were used for the analysis of damping values and source parameters. The non-linear damping values of the deep and shallow crustal materials were found to be more similar to those of the region of the Western United States. The seismic source parameters found from this study also showed that the resultant stress drop values are relatively low compared to those of the Western United Sates. Consequently, comparisons of the various seismic parameters from this study and those of the United States Seismo-tectonic data suggest that the seismo-tectonic characteristics of the South eastern Korean Peninsula is more similar to those of the Western U.S.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.181-190
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• 2003

An investigation was conducted on the aquatic environment of the Okchon Stream watershed six times from May to September 2002. The results of investigation revealed that variation of environmental factors were quite significant for each stream and reach, showing a significant difference between running water and stagnant water. Aquatic nutrients were relatively low in the upstream, gradually increasing as the influx of treated wastewater into the stream increased. This suggests that the point source definitely affected the nutrient content of the stream. In particular, the variations of SRP and $NH_4$ were very distinct in the watershed compared to other nutrients. Thus, it can be considered as a major factor in evaluating the effect of treated wastewater. Immediately after the influx of treated waste-water, the average content of SRP rose to 919.3 ${\mu}g$ P/l. This was a very effective level in the watershed, suggesting that the percentage of the nutrients in the water was controlled by the content of P. The constant supply of treated wastewater was found to be a critical factor in triggering the increase in chl-a in the embayment of the stream. With the proliferation of the blue-green algae, the content of chl- a ranged 234.5${\sim}$1,692.2 ${\mu}g/l$. The maximum standing crops exceeded $1.0{\times}10^6$ cells/ml in August, which was more than 200 times the level for red tide in the freshwater. This result was well reflected in other environmental factors, with 100% of AFDM/TSS reflecting the severity of water pollution by algae. Therefore, the reduction of P and N con-tents in the treated wastewater is critical in improving the aquatic environment of the stream as well as water quality management for the reservoir.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.