• 한국토양비료학회지
• /
• 제49권5호
• /
• pp.495-502
• /
• 2016

Italian Ryegrass (IRG), which is known as high yielding and the highest quality winter annual forage crop, is grown in mid-south area in Korea. The objective of this study was to evaluate the use of unmanned aerial vehicle (UAV) for the monitoring IRG growth. Unmanned aerial vehicle imagery obtained from middle March to late May in Nonsan, Chungcheongnam-do. Unmanned aerial vehicle imagery corrected geometrically and atmospherically to calculate normalized difference vegetation index (NDVI). We analyzed the relationships between $NDVI_{UAV}$ of IRG and biophysical measurements such as plant height, fresh weight, and dry weight over an entire IRG growth period. The similar trend between $NDVI_{UAV}$ and growth parameters was shown. Correlation analysis between $NDVI_{UAV}$ and IRG growth parameters revealed that $NDVI_{UAV}$ was highly correlated with fresh weight (r=0.988), plant height (r=0.925), and dry weight (r=0.853). According to the relationship among growth parameters and $NDVI_{UAV}$, the temporal variation of $NDVI_{UAV}$ was significant to interpret IRG growth. Four different regression models, such as (1) Linear regression function, (2) Linear regression through the origin, (3) Power function, and (4) Logistic function were developed to evaluate the relationship between temporal $NDVI_{UAV}$ and measured IRG growth parameters. The power function provided higher accurate results to predict growth parameters than linear or logistic functions using coefficient of determination. The spatial distribution map of IRG growth was in strong agreement with the field measurements in terms of geographical variation and relative numerical values when $NDVI_{UAV}$ was applied to power function. From these results, $NDVI_{UAV}$ can be used as a new tool for monitoring IRG growth.

• 한국환경과학회지
• /
• 제12권11호
• /
• pp.1145-1157
• /
• 2003

The surface sediments inside Hallim Harbor, one of the major harbors of Jeju Island, were sampled three times (June, September and December, 2001) and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), recommended by US-EPA as priority pollutants, to assess their distribution levels and to suggest their possible origins. The concentrations of PAHs ranged from 19 to 496 ng/g on a dry weight basis with a mean value of 245 ng/g, and the levels were low to moderate in comparison with other areas in the world. Based on comparisons of individual and total PAH concentrations with effects-based and equilibrium partitioning-based on sediment quality guidelines, the potential for the biological effects were expected to be low. The sedimentary PAHs may be correlated with organic carbon and mud contents to some extent. From the examinations of the four PAH origin indices, such as LMW/HMW (low molecular weight 2-3 ring PAHs over high molecular weight 4-6 ring PAHs), phenanthrene/anthracene ratio, fluoranthene/pyrene ratio, chrysene/benzo〔a〕anthracene ratio, it can be concluded that the sediment PAH contaminations were ascribed to both pyrolytic and petrogenic origins.

• 한국수자원학회논문집
• /
• 제45권4호
• /
• pp.409-418
• /
• 2012

본 연구에서는 가뭄의 심도에 직접적으로 영향을 주는 무강수일수를 고려하고, 강수에서 기인하는 지표면유출 효과를 반영한 가뭄해갈에 유효한 강수를 산정하여 기존의 SPI3을 개선한 Modified SPI를 제시하였다. 1973년부터 2009년까지 각종 보고서 및 문헌자료를 통해 실제 발생한 가뭄사례를 수집하여 행정구역별 가뭄공간정보를 생산하고, 동일기간 전국 69개지점에서산정된 가뭄지수를 우리나라 전체 공간으로표현하여각종 지수의 적합성을 평가하기 위하여ROC 분석을 수행하였다. 개선된 가뭄지수 제시를 위하여 총 강우량 중단기적인 유출에 기여할 것으로 판단되는 부분을 절삭하여 유효강우를 산정하였으며, 월단위의 무강수일수를 십분위, 누적분포함수로 변형하여 기존의 지수에 가중치를 부여하였다. 분석결과 유출량을 고려한 강우의 절삭은 기존의 SPI3에 비하여 상대적으로 높은 가뭄감지능력을 보여주었으며, 무강수일수를 고려한 가뭄지수의 개선은 누적분포함수의 수치를 고려함으로서 상당히 개선된 가뭄감지 능력을 보여주었다.

• The Korean Journal of Ecology
• /
• 제24권1호
• /
• pp.19-26
• /
• 2001

대형조선소가 위치한 옥포만내 퇴적물, 해수, 참굴(Crassostrea gigas) 중의tributyltin(TBT)과 triphenyltin(TPhT), 그리고 분해산물의 농도를 분석하였다. 퇴적물과 참굴 내 TBT 농도는 각각 5~2,650 ng/g, 387~l,190ng/g dry wt.(as Sn)으로 검출되었다. 해수 중의 TBT 화합물은 19~84 ng/ $\ell$ 농도범위를 나타내었다. 조선소 내 dry-dock에 인접한 정점에서 최고값을 보이며, 조선소로부터 거리가 멀어질수록 감소하는 농토분포를 나타내었다. 이는 조선소가 옥포만내 주 오염원임을 의미한다. 퇴적물 중의 TBT 화합물의 구성비는 약 57%로 dibu-tyltin(DBT)와 monobutyltin(MBT)보다 높게 나타났다 만을 가로지르는 방파제를 경계로 하여 부틸주석 화합물(butyltin)의 농도가 급격하게 감소하여, 방파제가 옥포만 내 유기주석 화합물의 분포에 영향을 미치고 있음을 나타내었다. 페닐주석화합물은 참굴 중 nd-52 ng/g으로 검출되었으며, 퇴적물과 해수의 전 정점에서 검출한계 이하의 값을 보였다. 참굴 중의 TBT 농도는 대조구인 해금강의 시료보다 높은 값을 보였고, 생물농축계수(biological concentration factor, BCF)는 1.1$\times$$10^4$의 값을 보였다.

• 한국초지조사료학회지
• /
• 제7권2호
• /
• pp.79-86
• /
• 1987

This study was carried out to investigate the relationships and the variations of agronomic characteristics in the shoot and root part of grasses for the basic data of the development, the management and the utilization of pasture in the forest. This study was conducted with 0% (full sunlight), 25%, 50% and 75% of shading degrees after orchardgrass, timothy, perennial ryegrass, ladino clover and orchardgrass dominated mixture were planted on Aug. 25 in 1984. The results are summarized as follows: 1. Dry matter yield in 25% of shading was increased 3-1 7% compared with 0% (full sunlight), while 50 and 75% of shading were decreased 28-35% and 44-60%, respectively. Dry matter yield of timothy, perennial ryegrass and ladino clover were decreased 10, 8 and 33%, respectively, compared with orchardgrass, but there was little difference between orchard grass and mixture. 2. Root distribution by different shading degrees was the maximum at 25%, followed by 0, 50 and 75% of shading degrees. Root distribution among different species was the maximum at orchardgrass, followed by perennial ryegrass and timothy. Especially, root distribution of timothy was very little compared with different species. And significantly positive correlation was observed in the relationship between root weight and dry matter yield (r=0.8 102**). 3. The physiological activity of root by different shading degrees was declined by more shading. 4. The length and the percentage of blade by different shading degrees was an increase tendency by more shading. The length and the percentage of blade among different species was followed by timothy, perennial ryegrass and orchardgrass, in that order. And the correlation between the percentage of blade and dry matter yield was significantly negative.

• 대한환경공학회지
• /
• 제31권5호
• /
• pp.346-351
• /
• 2009

청주시 토양을 대상으로 다이옥신의 오염수준 및 특성에 대해 조사하였다. 채취된 28개 지점의 토양 중 17개 다이옥신 이성질체의 농도범위는 2.30${\sim}$630.40(평균 55.42) pg/g-dry으로 검출되었으며 TEQ 농도범위는 0.002${\sim}$9.79(평균 1.13) pg I-TEQ/g-dry로 조사되었다. 이들 농도는 우리나라 소각시설 주변의 농도(불검출${\sim}$153.23, 평균 7.36 pg I-TEQ/g-dry)보다 매우 낮은 수준을 나타내었다. 총농도와 TEQ 농도와는 99% 신뢰구간에서 서로 상관성을 나타냈다(p값<0.001). 토지이용별 농도는 공단>녹지>주거 및 상업지>농경지의 순으로 높게 나타났다. 이성질체 조성에 있어서는 일반적으로 토양 중에서 높게 검출되는 OCDD의 비율이 22${\sim}$100%(평균 59%)로 채취지점에 따라 편차가 심하였으며, PCDF/PCDD의 비율 또한 0.1${\sim}$2.4(평균 0.8)로 지점에 따라 편차를 보였다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제4권1호
• /
• pp.99-102
• /
• 1991

To determine effect of time after feeding on distribution of digesta in the gastro-intestinal tracts of sheep given orchardgrass hay once a day, a total of fifteen ewes (mean live weight $51{\pm}12kg$) were slaughtered at 2, 8, 16 and 24 hours after feeding. Contents in the reticulo-rumen, omasum, abomasums, small intestine, cecum, and colon and rectum were totally collected and weighed. Weights of digesta in the reticulo-rumen were about 6 kg which contributed about 75% of the total in the whole tracts. Digesta on dry-matter basis totaled about 1 kg. The dry-matter concentration of digesta in the whole digestive tract was about 107 h/kg of fresh digesta. Distribution of moisture in the digestive tract changed in parallel with that of fresh digesta. There was no significant correlation observed between time after feeding and weights of digesta in the gastro-intestinal tracts. While, feed intake significantly correlated with digesta in the reticulo-rumen, cecum and whole tracts (p<0.01). Thus, time after feeding was inferred to have no influence upon the content of digesta in the digestive tract, but feed intake influenced on the content of digesta in the digestive tract at a low level of feeding.

• The Korean Journal of Ecology
• /
• 제22권2호
• /
• pp.89-94
• /
• 1999

Thirty-day-old seedlings of tomato (Lycopersicon esculentum) were treated with different concentrations of HgCl$_2$(0. 10 and 50 $\mu$M) for up to 20 days. and the detailed distribution of Hg absorbed and its toxicity in different plant parts (roots, stems and leaves) were investigated. The accumulation of Hg in plants increased with external Hg concentrations. and Hg is strongly retained by roots. Further. Hg content in leaves was various. showing more accumulation in older leaves. Seedlings exposed to toxic levels of Hg showed not only the reduction of dry weight and length of both shoot and root. and chlorophyll levels in leaves but also the enhancement of malondialdehyde (a lipid peroxidation product) formation in all plant parts investigated. These results suggest that physiological impairment of a plant exposed to Hg may be achieved by internal distribution of Hg absorbed and Hg-induced oxidative stress in different plant parts.

• The Korean Journal of Ecology
• /
• 제20권4호
• /
• pp.285-291
• /
• 1997

The taxonomic characteristics of Eupatorium rugosum were reviewed and growth responses under different light intensities were investigated. Changes of soil and vegetation environments at experimental plots on Mt. Namsan were surveyed and the distribution pattern examined. The distribution of E. rugosum was closely related to the content of total nitrogen and available phosphorus in the soil. No competitors which could inhibit the growth of E. rugosum were present. Growth of E. rugosum was highest at a light intensity of 7, 500 lux, but dry weight was highest at a light intensity of 15, 000 lux followed by 30, 000 and 7, 500 lux. Growth in height of E. rugosum under a light intensity of 1, 500 lux continued even though the amount of growth was small. E. rugosum is found throughout the area of Mt. Namsan, and its density is higher at the roadside and in valley regions. E. rugosum appeared at 25 of 50 quadrats on Mt. Namsan, and the mean coverage of E. rugosum in survey quadrats was 12%.

• 지질공학
• /
• 제20권4호
• /
• pp.415-424
• /
• 2010

콘크리트 표면차수벽형 석괴댐에서 Zone별 거동특성을 평가하기 위하여 시험성토를 실시하였다. 본 연구에서는 기존의 시방기준에 제시된 각 Zone에 대한 축조재료 기준을 만족하는 시험재료를 선정하여 포설두께, 전압회수 및 함수비 등을 변경시키면서 다짐성토를 실시하였다. 이때의 시험다짐에 대한 성토체의 침하율, 다짐밀도, 함수비 및 투수계수의 변화를 측정하였다. 시험분석 결과 전압회수와 현장다짐밀도관계, 현장다짐밀도와 침하율의 관계, 다짐회수와 침하율의 관계, 침하율과 포설두께의 상관관계 등을 제시하였다. 특히, 투수계수와 다짐전압회수와의 관계를 제시하였고 이러한 연구를 통하여 효율적인 다짐관리기준을 마련하고자 하였다.