• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.227-237
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• 2012

This paper analyzes the current status, characteristics, and problems of coastal reclamation in Korea and suggests effective management approaches. Reclamation is concentrated from the West Sea to the South Sea. In the 1980s and 1990s, most projects were intended for agricultural use, whereas in recent years reclamation for industrial and harbour sites(e.g., ship-building) have been increasing. The continuous onslaught of reclamation and development projects threatens the coastal environment, especially tidal flats and fishing areas, and fishery production has been reduced in some areas. The largest tidal flats have been used for dumping sites of dredged coastal sediments, urban development projects, and industrial complex composition. Thus, it is necessary to assess current policy using top-down approaches after establishing appropriate directions and standards for coastal management. Both short-term development profits and long-term conservation should be considered when attempting to balance development and conservation. In addition, improvements of marine environmental impact assessment and in the legal system are necessary.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.434-442
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• 2014

Serious environmental problems have been caused by the greenhouse effect due to carbon dioxide($CO_2$) or nitrogen oxides($NO_x$) generated by the use of fossil fuels, including oil and liquefied natural gas. Many countries, including our own, the United States, those of the European Union and other developed countries around the world; have shown growing interest in clean energy, and have been concentrating on the development of new energy-saving materials and devices. Typical non-fossil-fuel sources include solar cells, wind power, tidal power, nuclear power, and fuel cells. In particular, organic solar cells(OSCs) have relatively low power-conversion efficiency(PCE) in comparison with inorganic(silicon) based solar cells, compound semiconductor solar cells and the CIGS [$Cu(In_{1-x}Ga_x)Se_2$] thin film solar cells. Recently, organic cell efficiencies greater than 10 % have been obtained by means of the development of new organic semiconducting materials, which feature improvements in crystalline properties, as well as in the quantum-dot nano-structure of the active layers. In this paper, a brief overview of solar cells in general is presented. In particular, the current development status of the next-generation OSCs including their operation principle, device-manufacturing processes, and improvements in the PCE are described.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.141-142
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• 2007

In recent years, the rate of mean sea level rise is increasing rapidly from the phenomena of global warming, together with the increasing trend of the storm scale. The issue of sea level rise is multifaceted and produces a range of environmental problems. Especially, high tides and the tidal currents become higher, and wave base increases, so the energy received at the coastal boundary may increase. This brings that many coastal environments go into disequilibrium, such as damages to the structures, erosion, and deposition Similarly it was known that the problems of nearshore processes and damage of berth and counter facilities during storm period had appeared at the small fishery port. Here we try to analyze the impact of the rearrangement of counter facilities and berth layout adopted for tranquility of its'inner harbor. Because this harbor is being connected to channel and open sea, the rearrangement of the structures might affect to the current speed and direction and wave height, so do to the sea bottom undulation. Therefore, we made model test for the several layouts of the berth and breakwater in this area.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.102-114
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• 2013

The basin of Lake Shihwa is one of highly industrialized region of Korea and a current environmental issue of study area is the operation of tidal power plant (TPP) to improve water quality. The application of water quality index (WQI) which integrates five physiochemical parameters (transparency, DO, DIN, DIP and chlorophyll-a) of water quality in Lake Shihwa and outer sea during 2011~2012 were performed not only to evaluate the spatial and temporal distribution of the water quality but also to assess the effect of water quality improvement by the operation of tidal power plant. The higher WQI values were observed in monitored sites near the industrial complexes in Lake Shihwa and the outfall of wastewater treatment plants (WWTPs) in outer sea. This indicates that the quality of seawater is influenced by diffuse non-point sources from industrial, municipal and agricultural areas in Lake Shihwa and by point sources from the effluence of municipal and industrial wastewater throughout WWTPs in outer sea. Mean WQI value decreased from 53.0 in 2011 to 42.8 in 2012 of Lake Shihwa. Water quality has improved significantly after TPP operation because enhancement of seawater exchange between Lake Shihwa and outer sea leads to improve a hypoxic condition which is primarily a problem in Lake Shihwa. Mean WQI of outer sea showed similar values between 2011 and 2012. However, the results of hierarchical cluster analysis and the deterioration of water quality in summer season indicate that the operation of tidal power plant was not improved the water quality in the upper most area of Lake Shihwa. To successfully improve overall water quality of Lake Shihwa, it is urgently necessary to manage and reduce of non-point pollution sources of the basin of Lake Shihwa.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.56-61
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• 2009

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

• Geophysics and Geophysical Exploration
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• v.20 no.4
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• pp.199-206
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• 2017

Field data obtained from marine exploration are influenced by various environmental factors such as wind, waves, tidal current and flow velocity of a background medium. Most environmental factors except for the flow velocity are properly corrected in the data processing stage. In this study, the wave equation modeling considering flow velocity is used to generate observation data, and numerical experiments using the observation data were conducted to analyze the effect of flow velocity on waveform inversion. The numerical examples include the results with unrealistic flow velocities. In addition, an algorithm is suggested to numerically extract flow velocity for waveform inversion. The proposed algorithm was applied to the modified Marmousi2 model to obtain the results depending on the flow velocity. The effect of flow velocity on updated physical properties was verified by comparing the inversion results without considering flow velocity and those obtained from the proposed algorithm.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.626-629
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• 2007

국내외에 아직 개발 실적이 없는 발전소의 해수방류수를 이용한 조류식발전시스템의 개발을 위하여, 현재 하동화력발전소 해수방수로를 대상으로 헬리컬 수차를 이용한 조류식발전 시험설비를 제작 완료하고, 성능 시험이 진행 중이며, 본 연구에서는 성능 시험 과정에서 나타난 제반 문제점을 제시하고 그에 대한 원인 및 대책을 분석해 보았다. 본 시험설비는 인공수로에서 수평 배열 헬리컬수차로서 기계장치의 안정성 및 수차의 효율을 평가하고자 하였다. 조류식 시험장치는 배수로의 빠른 유속으로 인하여 시공이 매우 어려웠으며, 인공수로임에도 불구하고 유지관리를 위한 적정 구조 선정이 곤란한 상황이었다. 또한, 헬리컬 수차는 서로 직렬연결되어 운전할 수 있는 장점이 있으나, 본 연구와 같이 다수의 수차가 연결될 경우, 보다 높은 축정렬 정확성, 커플링, 베어링 정밀도 등이 요구되어 효율 감소의 원인이 됨을 확인하였다. 본 장치는 시험용으로서 정밀한 베어링 및 수밀구조, 증속장치를 채택하지 않았으나, 상업용에서는 이를 개선할 필요성이 있다고 판단된다. 또한, 수차의 설치와 유지관리 조건 향상, 수차 통과부의 유황 개선, 수차의 효율 향상을 위하여 조류식 수차에도 유도수로와 casing, draft tube와 같은 Confined flow 구조를 일부 채택할 필요성이 있다고 판단된다.

• Ocean and Polar Research
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• v.24 no.1
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• pp.55-61
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• 2002

Eelgrass, Zostera marina L. widely spreads throughout all the coastal areas of the Korean Peninsula. However, some previously reported eelgrass populations disappeared. The disappearance was probably caused by anthropogenic disturbance such as reclamation and pollutant or exceeded nutrient release. Eelgrass beds occurred from the intertidal to the subtidal zone, mainly in lagoon, estuaries, ports, barrier reef and bays. Eelgrass beds were also found at the intertidal mud and sand flats, subtidal mud and sandbank in more exposed areas. Habitat characteristics of eelgrass beds distributed on the coasts of the Korean Peninsula varied among coast areas. Eelgrass distributed constantly throughout the southern coast of Korea, while the distribution was limited at lagoon, bay, port, or barrier reef on the eastern coast, because of steep water depth and high wave energy in that coast. On the western coast, eelgrass mainly appeared at the intertidal and subtidal zones in islands. Sediment characteristics of the Z. marina beds varied with locality, tidal current and water motion. Sediments of Z. marina beds were composed of sand, muddy sand, sandy mud and mud. Mean grain size ranged from 1.5 to 4.1 phi.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.250-255
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• 2016

Ocean environmental data such as tide, wind, significant wave height etc. along the expected route were collected and analyzed to secure the safe towing and installation of floating pendulum wave energy converter(FPWEC) at planned sea area. Data from Korea Meteorological Administration(KMA) and Korea Hydrographic and Oceanographic Agency(KHOA) were reviewed and those were used to estimate the external forces exerting on the FPWEC during the towing operation. ANSYS system was used for the structural analysis of the FPWEC which is subject to complex environmental load to confirm the safety.

• Journal of Environmental Science International
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• v.11 no.7
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• pp.637-650
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• 2002

This study presents an investigation of the changes of the currents in Kwangyang Bay due to the construction of harbor, reclamation and coastal developments. Currents were simulated by the numerical experiments with a diagnostic multi-level model and using the seasonal oceanographic data of temperature, salinity and ocean current. The values of kinetic and potential energies for the currents were calculated in cases of three topographical changes; before coastal developments, the existing state and after completion of the development project in Kwangyang Bay. The changes of currents due to the coastal developments are as follow; Kinetic energies of tide induced residual currents and wind driven currents decreased by 35~40 percent and 5 percent respectively, however those of density currents increased by 10 percent since the decrease of the coastal areas. Kinetic energy of residual currents including tide induced residual currents, density currents and wind driven currents reduced by 10 percent compared with before the coastal developments. Decrease of current velocity was greatest in summer. Therefore, in summer it was assumed that the Kwangyang Bay is more easily polluted by stratification and decrease of residual current than before the coastal developments carried out.