• 폴리머
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• 제31권3호
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• pp.201-205
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• 2007

폴리락타이드, 폴리글리콜라이드, 및 글리콜라이드-락타이드 공중합체(PLGA)와 같은 생분해성 고분자들은 쉬운 약물방출량 조절과 부산물독성이 없이 지지체의 완벽한 분해과 좋은 생체적합성을 갖고 있다. 그러나 PLGA는 in vitro 실험에서의 괴상침식, 과도한 초기방출 후의 방출량이 감소하는 단점을 갖고 있다. 본 연구에서 PLGA 재결정 분말은 진공건조법을 이용하여 제조하였으며 1,3-bis(2-chloroethyl)-1-nitro-sourea(BCNU, carmustine)가 함유된 PLGA 웨이퍼의 방출거동을 알아보았으며 동시에 수용성 첨가제를 넣어 약물의 방출거동을 알아보고자 하였다. 진공건조법으로 재결정한 PLGA 웨이퍼가 일반방법으로 제조한 PLGA 웨이퍼보다 수분흡수율 감소와 웨이퍼 자체 초기의 분해 속도 감소로 인하여 초기 방출량이 감소하고 지속적 방출거동을 가지는 것을 확인하였다.

• 한국산림과학회지
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• 제102권2호
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• pp.176-181
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• 2013

산지계류에서 계상구조물의 설치에 따른 저서성 대형무척추동물의 출현종 및 개체수의 변화에 따른 서식처 영향을 분석한 결과를 요약하면 다음과 같다. 계상구조물의 종류 및 위치에 따른 저서성 대형무척추동물의 출현종은 최소 16종에서 최대 40종 범위이며, 개체수는 최소 352 $inds./^2$에서 최대 4,333.3 $inds./m^2$ 범위로 나타났다. 돌바닥막이, 돌낙차공 및 콘크리트바닥막이와 같은 계상구조물의 설치는 계상의 안정을 주어 종적인 침식을 막고 유속을 감소시키는 역할을 하지만 구조물 인접지점과 상류부 및 하류부에 수심이 깊고 단조로운 소와 폭호가 형성되어 있는 지점은 계류의 균일한 구조적인 연속성을 저해하고 미소서식처의 인위적 및 자연적인 교란으로 서식공간이 제한되어 저서성 대형무척추동물의 출현종수 및 개체수가 줄어 생물 다양성이 감소되는 것을 알 수 있다. 따라서, 산지계류의 생태적 안정을 위하여 계획 단계에서부터 생물서식처의 훼손이 최소화될 수 있도록 계상구조물이 설치될 위치 주변에 서식공간의 확보 등 적절한 대책이 필요할 것으로 판단된다.

• 한국환경복원기술학회지
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• 제19권2호
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• pp.121-135
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• 2016

The present study is an analysis of the monitoring results of the four areas that underwent the experimental construction of Straw-net+seedspray, Vegetation media spray method(t=2cm), and Vegetation media spray method(t=3cm), with the purpose of selecting the adequate revegetation of cutting slopes in weathered granite soil. Cutting slopes are mostly designed in the Straw-net+seedspray method, but since weathered granite soil slopes tend to have an infertile soil quality that runs down, it is difficult for seed germination and growth. It is difficult to apply Straw-net+seedspray to weathered granite soil slopes considering the germination rate and coverage rate of the Straw-net+seedspray method, which accompanies erosion and scouring. The final conclusions are summarized as follows. First, Straw-net+seedspray has difficulty recruiting plants to infertile weathered granite soil, which results in a lower coverage rate and fewer species, so it is not adequate construction method. Second, Vegetation spraying methods with wet media are more advantageous in early revegetation. The wet construction methods are faster than the dry construction methods in terms of early germination and its early growth are more excellent. Third, when constructing Vegetation spray methods with dry media, it were more advantageous if the thickness was thicker. When the soil-media is thicker, the soil is resilient to droughts, so the thickness must be flexibly applied according to the soil quality and slant of the weathered granite soil slope. The present study is a monitoring result for some areas of Gangwon-do, so its results may differ from other areas.

• 한국지반신소재학회논문집
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• 제14권2호
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• pp.11-21
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• 2015

2002년 피해조사 결과에 따르면, 하천제방 관련 홍수피해는 월류, 침식, 제체불안정(파이핑, 부적절한 축제재료선정, 다짐불량 등), 구조물에 의한 파괴 등으로, 월류에 의한 제방붕괴는 39.5 %로서 주요 요인인 것으로 평가되었다. 한편, 제방붕괴각(${\theta}$), 제방붕괴율(k) 등 관련 월류제방 붕괴특성은 침수모델링 해석 시 침수속도 및 면적 등에 영향을 미치나 국내 관련 연구 실적이 미진한 실정에 있다. 본 논문에서는 프루드(Froude) 상사(${\lambda}_{Fr}=1$)를 가정한 제방고(0.20 m, 0.25 m, 0.30 m, 0.40 m)에 따른 제방붕괴모형실험을 수행하여 제방고 변화(H)에 따른 제방붕괴 메카니즘, 붕괴연장, 제방붕괴각(${\theta}$), 제방붕괴율(k) 등을 제시하였다.

• 동력기계공학회지
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• 제20권4호
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• pp.32-37
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• 2016

This paper proposes two measurement methods for injured rate of fish surface using color image segmentation method based on K-means clustering algorithm and Otsu's threshold algorithm. To do this task, the following steps are done. Firstly, an RGB color image of the fish is obtained by the CCD color camera and then converted from RGB to HSI. Secondly, the S channel is extracted from HSI color space. Thirdly, by applying the K-means clustering algorithm to the HSI color space and applying the Otsu's threshold algorithm to the S channel of HSI color space, the binary images are obtained. Fourthly, morphological processes such as dilation and erosion, etc. are applied to the binary image. Fifthly, to count the number of pixels, the connected-component labeling is adopted and the defined injured rate is gotten by calculating the pixels on the labeled images. Finally, to compare the performances of the proposed two measurement methods based on the K-means clustering algorithm and the Otsu's threshold algorithm, the edge detection of the final binary image after morphological processing is done and matched with the gray image of the original RGB image obtained by CCD camera. The results show that the detected edge of injured part by the K-means clustering algorithm is more close to real injured edge than that by the Otsu' threshold algorithm.

• 한국물환경학회지
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• 제25권1호
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• pp.102-111
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• 2009

Turbid storm runoff from intensive highland agriculture area has emerged as the major problem of water quality deterioration in the upstream region of the Han River. High slope of the upland combined with high rate of fertilization and intensive plowing causes high rate of soil erosion, and subsequently high suspended sediment and phosphorus content in the runoff water. The variations of water quality during rain spells were surveyed for two years (2005 and 2006) in the Jawoon Stream that is one of hot spots of intensive horticulture discharging turbid storm runoff. SS and TP showed large increase according to the increase of flow rate, whereas TN and BOD showed less fluctuations. Mean EMCs of SS and TP measured for nine rain events were as high as $207mgSS{\cdot}L^{-1}$ and $0.27mgP{\cdot}L^{-1}$, respectively. The export coefficient of SS and TP per area of cultivated field were calculated as $11,912kgSS{\cdot}yr^{-1}{\cdot}km^{-2}$ and $785kgP{\cdot}yr^{-1}{\cdot}km^{-2}$, repectively, which are significantly higher than reports of other area. It can be concluded that SS and TP in the runoffs were high enough to impose major threat to aquatic habitats, and the highland agriculture should be the main target of water quality management or habitat conservation in the study area.

• 한국물환경학회지
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• 제33권6호
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• pp.661-669
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• 2017

A distributed watershed model CAMEL (Chemicals, Agricultural Management and Erosion Losses) was applied to a small rural watershed where intensive livestock farming sites are located to estimate nitrate leaching rates from soil to groundwater. The model was calibrated against the stream flows, and T-N and $NO_3-N$ concentrations were observed at the watershed outlet for three rainfall events in 2014. The simulation results showed good agreement with the observed stream flows ($R^2=0.67{\sim}0.93$), T-N concentrations ($R^2=0.40{\sim}0.58$) and $NO_3-N$ concentrations ($R^2=0.43{\sim}0.65$). The estimated annual nitrate leaching rate of the watershed was 33.0 kg N/ha/yr. The contributing proportions of individual activities to the total nitrate leaching rate of the watershed were estimated for livestock farming, applications of chemical fertilizer, and manure. The simulation results showed that the highest contributor to the nitrate leaching rate of the watershed was chemical fertilizer applications. The simulation period was for one year only, however, and results may vary depending on different conditions. Gathering input data over a longer period of time and monitoring data for calibration is needed. When this has been accomplished, it is expected that this model can be applied to small rural watersheds for evaluating temporal and spatial variations of nitrogen transformations and transport processes.

• 농약과학회지
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• 제17권4호
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• pp.256-263
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• 2013

작물재배 관행과 지형에 의한 농약의 유실양상의 차이를 파악하고자 고추재배 경사지 포장에서 농약유출 실험을 수행하였다. Fluazinam 50% 수화제를 2003년부터 2005년까지 7월 중에 살포한 후 작물체를 씻어 내리는 빗물(wash-off), 유출수, 유실토 및 토양 중 fluazinam의 잔류소실 양상을 추적하였다. 농약살포 후 작물체 표면에 부착되었던 fluazinam이 빗물에 씻겨 내리는 정도는 살포량의 1.4~8.2%이었다. Fluazinam의 유출률은 등고선방향 비닐피복구의 경우 1년차 0.14~0.90%, 2년차 0.01~0.04%, 3년차 0.16~0.37%이었고 상하경 비닐피복구 0.47~1.59% 및 등고선방향 무피복구 0.07~1.05%로 경사도에 따라 유출률이 증가하는 것으로 나타났다. 첫 번 유출에 의한 fluazinam의 유출농도는 대부분 10 ${\mu}gL^{-1}$ 이하였다. 상하경 비닐피복구를 제외한 토양유실에 의한 fluazinam의 포장외부로의 경사도별 유출률은 10% 경사구와 20% 경사구는 0.00~0.21%이었고 30% 경사구는 0.15~1.05%이었으며, 상하경 비닐피복구의 유실률은 경사도 10%구와 20%구에서 각각 0.47~1.59%와 0.75~1.05%이었다. 농약살포 10일 경과 후 비닐피복부분을 제외한 고추밭 토양 중 fluazinam의 잔류농도는 0.007~0.059 mg $kg^{-1}$이었고 토양반감기 20일의 속도로 소실되어 살포 60일 경과 후에는 0.01 mg $kg^{-1}$ 미만으로 감소하였다.

• Applied Science and Convergence Technology
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• 제27권1호
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• pp.9-13
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• 2018

Samples of anodic oxide film used in semiconductor and display manufacturing processes were prepared at different electrolyte temperatures to investigate the corrosion resistance. The anodic oxide film was grown on aluminum alloy 6061 by using a sulfuric acid ($H_2SO_4$) electrolyte of 1.5 M at $0^{\circ}C$, $5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, and $20^{\circ}C$. The insulating properties of the samples were evaluated by measuring the breakdown voltage, which gradually increased from 0.43 kV ($0^{\circ}C$) to 0.52 kV ($5^{\circ}C$), 1.02 kV ($10^{\circ}C$), and 1.46 kV ($15^{\circ}C$) as the electrolyte temperature was increased from $0^{\circ}C$ to $15^{\circ}C$, but then decreased to 1.24 kV ($20^{\circ}C$). To evaluate the erosion of the film by fluorine plasma, the plasma erosion and the contamination particles were measured. The plasma erosion was evaluated by measuring the breakdown voltage after exposing the film to $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas. With exposure to $CF_4/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.41 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0.83 kV. With exposure to $NF_3/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.38 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0. 77 kV. In addition, for the entire temperature range, the breakdown voltage decreased more when sample was exposed to $NF_3/O_2/Ar$ plasma than to $CF_4/O_2/Ar$ plasma. The decrease of the breakdown voltage was lower in the anodic oxide film samples that were grown slowly at lower temperatures. The rate of breakdown voltage decrease after exposure to fluorine plasma was highest at $20^{\circ}C$, indicating that the anodic oxide film was most vulnerable to erosion by fluorine plasma at that temperature. Contamination particles generated by exposure to the $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas were measured on a real-time basis. The number of contamination particles generated after the exposure to the respective plasmas was lower at $5^{\circ}C$ and higher at $0^{\circ}C$. In particular, for the entire temperature range, about five times more contamination particles were generated with exposure to $NF_3/O_2/Ar$ plasma than for exposure to $CF_4/O_2/Ar$ plasma. Observation of the surface of the anodic oxide film showed that the pore size and density of the non-treated film sample increased with the increase of the temperature. The change of the surface after exposure to fluorine plasma was greatest at $0^{\circ}C$. The generation of contamination particles by fluorine plasma exposure for the anodic oxide film prepared in the present study was different from that of previous aluminum anodic oxide films.

• 대한지리학회지
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• 제49권1호
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• pp.1-17
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• 2014

본 연구는 태백산맥 남부에 위치한 울진 광천, 평해 남대천, 영덕 오십천을 대상으로 하안단구 지형 특성,분포, 형성시기, 하각률을 분석하여, 지반융기와 기반암 특성에 의한 하안단구 형성과정을 추정하였다. 울진 광천 상류부의 구조 및 기후단구 1면은 하상비고 9~12m, 형성 시기는 MIS 2, 하각률은 0.40m/ka로 분석되었으며, 영덕 오십천 상류부의 구조 및 기후단구 1면은 하상비고 7~10m, 형성 시기는 MIS 3, 하각률은 0.10m/ka로 계산되었다. 이러한 결과는 울진 광천 유역이 영덕 오십천 유역에 비해 상대적으로 지반 융기율이 클 가능성을 의미한다. 울진 광천의 하류부는 영덕 오십천과 달리 해면변동단구가 확인되지 않는데, 울진 광천은 큰 융기율과 풍화 침식에 강한 기반암으로 인해 하곡에서 지형의 잔존 가능성이 낮은 것으로 보인다. 한편, 연구 대상 하천의 구조 및 기후단구는 가장 낮은 단의 형성시기가 다르고, 간빙기 내 기온 저하기와 아간빙기에 형성된 단구면도 확인되었다. 따라서 기존 기후단구 모델에 따른 하안단구 편년 방법에 대해 재고할 필요가 있다.