• 기계와재료
• /
• v.22 no.4
• /
• pp.92-101
• /
• 2010

화석 에너지 고갈과 지구온난화의 위기로 인하여, 미개척 분야인 해양에너지 산업에 대한 전 세계적 관심이 높아지고 있다. 특히 조력발전, 조류발전 그리고 해류발전은 현 정부의 녹색성장기술 신재생에너지에 속한 산업 군으로서, 정부정책 기조와 일치하는 해양 분야의 신성장 동력 아이템이다. 조력발전의 경우 우리나라는 조석간만의 차가 큰 서해안의 지형적 이점을 바탕으로 세계 시장에서 높은 경쟁력 가지고 있으며, 국내에서도 상용화를 위한 조류발전기 개발 및 실증시험을 진행하고 있다. 그러나 해류발전은 그 개념이 국내에서 확립되어 개발 초기단계에 있는 해양발전의 새로운 영역으로서, 전 세계적으로 개발사례가 없다. 해류발전용 해류발전기는 조류발전기에 비하여 크기가 작으나 발전용량이 크며, 개발 및 제작비용이 저렴하므로 조력발전소나 방조제의 수문 근처에 추가적으로 설치하면 매우 큰 시너지 효과를 얻을 수 있을 것으로 기대된다. 본고에서는 조력, 조류 및 해류발전에 대한 개념 소개와 조력발전과 조류발전의 국내외 개발현황 분석 그리고 새로운 개념인 해류발전에 대한 기술적 가능성을 제시하고 기대효과를 간략하게 소개하였다.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.11
• /
• pp.780-785
• /
• 2012

Existing states of attached algae in the sedimentation basin was observed during late april to early october, and the attached algae were visible 7 days after of cleaning the trough and the communities of algae became larger with increasing the operation periods. Attached algae community included bluegreen algae (Oscillatoria sp.), diatom (Synedra sp.,) and green algae (Mougeotia sp., Oedogonium sp.) and suspended diatom (Stephanodiscus sp.) as well. Diatom (Cymbella sp., Navicula sp., Synedra sp. and Stephanodiscus sp.), green algae(Mougeotia sp. and Cosmarium sp.) and blue-green algae (Anabaena sp.) were detected in the effluent of sedimentation basin. The chlorophyll-a (chl-a)concentrations of algae community on a square centimeter after 14 and 28 days were distinctively different depended on the copper sulphate treatment. The concentration of chl-a were $4{\mu}g/L/cm^2$ and $19{\mu}g/L/cm^2$ for the copper sulphate treated water and $59{\mu}g/L/cm^2$ and $147{\mu}g/L/cm^2$ for the untreated water. Diatom algae fragments were observed in red-brownish sediments on the bottom of industrial water distribution basin and degraded blue-green and green algae formated organic sediments combined with oxidized iron.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.4
• /
• pp.473-480
• /
• 2013

The purpose of this paper is to demonstrate that the genetic algorithm can be useful for the global path planning when the obstacles and current field data are given. In particular, the possibilities for a novel type small AUV mission deployment in tidal regions, which experience vortical currents, were examined. Experimental simulations show feasibility and effective in generate the global path regardless of current and obstacles. By choosing an appropriate path in space, an AUV may both bypass adverse currents which are too fast to be overcome by the vehicle's motor and also exploit favorable currents to achieve far greater speeds than motors could otherwise provide, while substantially saving energy.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.1
• /
• pp.13-19
• /
• 2000

Seasonal variations of dominant algae species and the effects of these algae on coagulation and filteration of water treatment were investigated at Chilseo water treatment plant in downstream of Nakdong river from January in 1995 to Desember of 1998. The water quality of Nakdong river was found to be a hyper eutrophic state during the investigation periods. In the measurement, Chlorophyll-a contents ranged $20.7{\sim}180.9{\mu}g/l$ and total nitrogen contents(T-N) and total phosphorus contents(T-P) exceeded more than 3.4mg/l and 0.1mg/l, respectively. The changes in dominant algae species was in the order of Stepanodiscus sp., Asterionella sp., Melosira sp., Microcystis sp. and Synedra sp. from spring to winter. Microcystis sp. especially, was blooming during summer and Synedra sp. and Stepanodiscus sp. during winter. Although most diatomous algae appeared in the water treatment process caused filter clogging and reduced efficiency of coagulation and sedimentation, Synedra sp. and Stepanodiscus sp were revealed as the main trouble algae. Malfunction of water treatment process caused by Synedra sp. and Stepanodiscus sp. started at the algae concentrations of 800cells/ml and 1,820cells/ml, respectively. When chlorophyll-a content was $18.9{\mu}g/l$, the optimum amounts of coagulant were found to be 40mg/l of Alum and 16mg/l of PACS. Under condition of chlorophyll-a content of $154.1{\mu}g/l$, addition of Alum at the level of 75mg/l and PACS at the level of 35mg/l showed the lowest turibidity. The result indicates that increased amounts of the coagulants should be added for a better water treatment as chlorophyll-a contents increased. Addition of Alum at the amount of 60mg/l and 30mg/l of PACS removed Stepanodiscus sp. algae at the rate of 85% and 83%, respectively. In case of Synedra sp., 50mg/l of Alum and 25mg/l of PACS showed removal rates of 79% and 81%, respectively. Synedra sp. algae at the standing crops of 1,500cells/ml started filter clogging and a filtering process was completely inhibited after 8 hours. At this situation the filter clogging by Synedra sp. algae occurred at the depth of 5cm from the top anthracite layer. On the other, other algae did filter clogging at the depth of 10cm.

• Korean Journal of Ecology and Environment
• /
• v.39 no.2 s.116
• /
• pp.257-264
• /
• 2006

In order to evaluate the application of Algae Online Analyzer (AOA), an instrument of automatic measurement of chlorophyll a concentration, was tested and compared with the acetone extraction method on the basis of microscopic counting of phytoplankton in field water (Paltang Reservoir). We simultaneously conducted AOA operation and extraction method with the same water sample, to compare both results of chlorophyll a measurement. Phytoplankton were enumerated by inverted microscope with the Sedgwick-Rafter chamber, and classified into the genus or species. According to the AOA measurement, the diatom most (83.6%) strongly contributed to the total chlorophyll a concentration, followed by chlorophyceae> cyanophyceae>cryptophyceae. Overall, the results of both AOA and extraction method showed a similar trend and significant correlation (r=0.87, n=302, p<0.001), however, there were some differences according to the season and species. In particular, the relationship between AOA Chl-a density of the diatom (r=0.73, p=0.010) and cyrptophyceae (.=0.83, p=0.00154) were siginificant, while chlorophyceae (r= -0.13) and cyanophyceae (r= -0.16) showed no clear relationship during the study period. Although we can not fully understand why there was difference between both mothods, AOA application for alarming algal bloom and water quality management during the algal bloom appears to be very relevant. However, the further study or technical upgrade of AOA measurement is required, especially in the case of low density of phytoplankton or species-specific measurement.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.4
• /
• pp.207-218
• /
• 2013

This study is based on a series of numerical modeling experiments to understand the circulation and its change in the Chunsu Bay (CSB), Yellow Sea of Korea. A skill analysis was performed for the tidal height and tidal current of the observation data using the amplitude and phase of the 4 major tidal constituents respectively for verification of modeling experimental results. As a result, most of the skill score was seen to be over 90%, so numerical model experiment results can be said to be in good agreement with the observed tidal height and tidal current. Tidal wave proceeded from the entrance of the CSB towards inside, and the tidal range gradually increased to the north. It took about 10 to 30 minutes for the tidal wave to reach to northern end. The tidal wave showed a characteristic to rotate counter-clockwise in the southern part. The tidal current flowed to the north-south direction along the bottom topography; the angle of the major axis appeared alongside the isobath. It showed the characteristics of reversing tidal current with the minor axis less than 10% of the major axis. The strength of the tidal residual current that is influenced by geographical factors including bathymetry and coastline showed the range of 1~30 cm/sec, greater in the south channel and smaller in northern Bay. Two pairs of cyclonic/anti-cyclonic eddies around Jukdo and 3~4 pairs of strong eddies at the southern part of CSB in hundreds of m to a few km size by relative vorticity derived from the tidal residual current.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.5
• /
• pp.430-434
• /
• 2001

The algicidal activity of Shewanella (formerly Alteromonas) sp. SR-14 against diatom, Chaetoceros calcitrans was reported in our previous papers. In this study, the effect of Vibrio alginolyticus on the algicidal activity of Shewanelia sp, SR-14 was examined under the optimum algicidal conditions, i.e., temperature ($21\pm1^{\circ}C$), light intensity (4,000 lux), and light: dark cycle (12 hour: 12 hour). Shewanella sp. SR-14 grew well in the presence or the absence of V. alginolyticus in Conwy medium. Algal growth was only inhibited by Shewanella sp. SR-14. V. alginolyticus did not show the algicidal activity, Growth of C. calcitrans increased synergistically with growth of V. alginolyticus. When the initial inoculum of V. alginolyticus was only 1 log cycle higher than that of Shewanella sp. SR-14, the effect of V. alginolyticus on the algicidal activity of Shewanella sp. SR-14 was insignificant during incubation of mixed culture, i.e., two bacterial species and the alga. However, when V. alginolyticus dominated Shewanella sp. SR-14 by 3 log cycles of bacterial counts, it was found that the strain SR-14 could not inhibited growth of C. calcitrans up to 5 days of incubation.

• Journal of Korea Water Resources Association
• /
• v.45 no.9
• /
• pp.915-928
• /
• 2012

Han River estuary (HRE) is located at the middle of the western coast of Korea, and tidal currents were measured at 4 stations in this estuary during the winter season, and previously observed tide data was analyzed. The results of amplitude ratio of $M_4/M_2$ showed that increasing upward to estuary in the HRE. Tide harmonic constants of relative phase $2M_2-M_4$ represent flood dominance, with under 180 degree. But this method has a limit of analysis that typically based on the non-linear distortion of the tidal current in tidal lagoon system where freshwater discharge is assumed to be relatively small. The results of statistically tidal current data indicated that ebb current velocity would be great unlike tide data. Ebb and flood duration time is calculated by slack time of tidal current showed that ebb duration time is longer than flood. The results of correlation of analysis show high value (0.9) between tidal current stations from Incheon harbor to north entrance of Yeomha channel. We reconstructed to find the reasons for the features of ebb dominance the results of harmonic analysis. As major component ($M_2$) in combination with shallow water component ($M_4$), the tidal curve was presented flood dominance that has a flood current is stronger. However, these curve were changed to ebb dominance add up the non-harmonic components that had ebb direction flow by calculated tidally averaged current. The characteristic of enhancement on ebb is showed around the Yeomha channel in the HRE, because averaged flow which acts seaward such as long-term tidal current components due to non-linear effect and freshwater which overcome the flood current.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2002.11a
• /
• pp.107-115
• /
• 2002

본 연구는 해양 식물플랑크톤에 지속성 유기오염물질의 영향을 이해하기 위한 목적으로, 연안역에서 우점하는 식물플랑크톤 주요 5종 즉, 규조류 Skeletonema costatum, 침편모조류 Heterosigma akashiwo, 와편모류 prorecentrum dentatum, Prorocentrum minimum, Akashiwo sanguinea를 이용하여을 benzo[a]pyrene (PAHs)에 72시간동안 노출시킨 다음 각 종의 성장 및 저해, 회복능력 등을 조사하였고, benzo[a]Pyrene의 농도 0.1, 1, 5, 10 $\mu\textrm{g}$/l에 Heterosigma akashiwo(Raphidophyceae)를 노출시켜 시간에 따른 광합성률의 변화를 측정하였다. benzo[a]Pyrene에 72시간 노출시킨 후 S. costatum, P. minimum, P. dentatum, akashiwo의 세포수는 1-10 $\mu\textrm{g}$/l의 농도범위에서 극적인 감소를 보인 반면, A. sanguinea는 0.1-1 $\mu\textrm{g}$/l의 낮은 농도범위에서 지수함수적인 감소를 나타냈다. 성장저해 농도 ($IC_{50}$/)는 A. sanguinea가 0.43 $\mu\textrm{g}$/l로 가장 낮았고, H akashiwo(1.17 $\mu\textrm{g}$/l) S. costatum (3.34 $\mu\textrm{g}$/l), p dentatum (3.97 $\mu\textrm{g}$/l), p minimum (7.24 $\mu\textrm{g}$/l)의 순서로 증가하였다. BenEo[a]pyrene의 낮은 농도(1 $\mu\textrm{g}$/l)에 노출되었던 세포들은 5종 모두 시간이 경과함에 따라 회복하는 경향을 나타냈으나 고농도(10, 100 $\mu\textrm{g}$/l)에 노출시에는 P. minimum을 제외하고는 회복되지 않았다. 이러한 결과들은 조사된 5종 중에서 유각 와편모류 P. minimum이 benzo[a]pyrene에 가장 내성이 강하며, 무각 와편모류 A. sangulinea가 가장 약함을 의미한다. benzo[a]pyrene의 여러 농도수준에 노출시켰을 때 H. akashiwo의 광합성 능력은 낮은 농도들에서는 대조구와 유사하였으나, 5 $\mu\textrm{g}$/l의 높은 농도에서는 초기에 매우 낮은 광합성 능력을 보이다가 시간이 경과하면서 대조군보다 더 높은 경향을 나타냈다. 이러한 결과는 식물플랑크톤이 benso[a]pyrene의 낮은 농도에서 노출될 때는 이 물질을 탄소원으로 사용할 가능성이 있음을 시사한다. 본 연구의 결과들은 연안해역에 benso[a]pyrene과 같은 지속성 유기오염물질이 유입되었을 때 내정여부에 따라 식물플랑크톤 군집내 종 천이와 일차생산력에 크게 영향을 미칠 수 있음을 시사한다.

• Korean Journal of Ecology and Environment
• /
• v.41 no.1
• /
• pp.1-10
• /
• 2008

The seasonal variations of water quality and periphyton were investigated in an artificial stream (the Cheonggyecheon Stream) flowing through the Seoul City. TP showed a longitudinal gradient: 10 to $59{\mu}gP\;L^{-1}$ in the upper stream sites, and 15 to $90{\mu}gP\;L^{-1}$ in downstream sites. POP was a major form of TP in the water, occupying over 60%, while the proportion of DIP was less than 10% except for St. 4. N/P atomic ratio ranged from 78 to 554, which implies phosphorus would limit algal growth more than nitrogen. The biomass of periphyton did not show much difference among sites, and it was relatively higher in spring and fall season $(10\sim20{\mu}gChl\;{\alpha}cm^{-2})$ and lower in August $(<5{\mu}gChl\;{\alpha}cm^{-2})$, possibly because biofilms were washed off during spates of summer monsoon. Cyanobacteria was the dominant taxon in the periphyton community throughout the year. The periphyton standing crop can be classified as a nuisance level. It seems that phosphorus level is sufficiently high even though the input water is treated chemically, and modest water velocity $(20\sim90cm\;sec^{-1})$ and rocky bottom provide optimal conditions for periphyton growth.