• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.597-601
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• 2008

Calculations for the dissolution behavior of liquid $CO_2$ droplets released in the East Sea and the Clipperton Clarion from a moving ship and a fixed pipeline have been carried out in order to estimate the $CO_2$ dissolution characteristics in the ocean. The results show that the injection of liquid $CO_2$ from a moving ship in a high temperature point is an effective method for dissolution. Also, it is noted that the ultimate plume generated from $CO_2$ bubbles repeatsand shrinking due to the peeling from a fixed pipeline, and the presence of hydrate layer on a liquid $CO_2$ droplet acts as a resistant layer in dissolving liquid $CO_2$.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.66-69
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• 2006

The idea of $CO_2$ sequestration in the ocean is proposed to be an effective mitigation strategy to counteract potential global warming due to the greenhouse effect Therefore, in the present study, calculations of the dissolution behavior of $CO_2$ hydrate when liquid carbon dioxide is released at 1,000m and 1,500m in depth are performed. The results show the liquid $CO_2$ injected in the ocean becomes $CO_2$ bubble at between 350m and 500m in depth, and the injection from a moving ship is a more effective method of dissolution than through a fixed pipeline. It so also noted that the ultimate plume generated from $CO_2$ bubbles repeats expansion and shrinking due to the peel ins from a fixed pipeline.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.351-359
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• 2020

The algae biomass is considered as one of the potential sources of ocean renewable energy because it can be easily mass-produced with abundant sunshine in the vast ocean space. However, the practical use of the biomass has been hindered by the lack of efficient and cost-effective harvesting and maintenance system so far. The algae biomass aquaculture systems are installed in far offshore locations in much larger scales compared to the conventional aquaculture systems so that the automatic seaweed planting and harvesting system needs to operate in heavy sea conditions in far offshore location. In this research, we develop a concept design of a mega-scaled aquaculture system and an automatic seaweed planting and harvesting system, which can operate in heavy seas and mass-produce the algae biomass.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.243-246
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• 2010

기후변화와 저탄소녹색성장으로 풍력, 태양광 등 신재생에너지 산업에 대한 관심과 투자가 비약적으로 확대되고 있다. 아직까지 우리나라에서의 신재생에너지의 대부분은 풍력과, 태양광에너지 쪽에 집중이 되어 있지만, 해외에서는 해상풍력, 파력, 조력 등 해상에서의 신재생에너지의 성장이 크게 이루어지고 있다. 특히 최근 들어서는 육상 풍력의 문제점이 제기되고, 우리나라는 3 면이 바다로 이루어져 있기 때문에 해상에서의 신재생에너지 산업의 발전 가능성은 매우 크다고 할 수 있다. 이러한 해상 신재생에너지 산업의 발전의 토대가 되는 해상기상 정보의 통계 DB 구축으로 향후 발전설비 도입을 위한 근간 정보를 제공하고자 한다.

• The Journal of Fisheries Business Administration
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• v.54 no.2
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• pp.91-107
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• 2023

Offshore wind power development has been promoted in countries around the world to cope with global warming. Despite its many advantages, offshore wind power affects the marine environment during construction and operation. As a result, the reduction of fishing areas, changes in the habitat of marine animals, damage to fishing gear, and impeding the safety of fishing activities are occurring. If the offshore wind power generation project is carried out, a fishing damage investigation is nescssary. There are only four fishing damage investigations related to offshore wind power, which are being conducted similarly to the existing fishing damage investigation related to offshore construction. Therefore, this study reviewed and analyzed the report on fisheries damage investigation related to offshore wind power conducted in Korea and suggested problems and improvement measures accordingly.

• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.382-392
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• 2021

In recent years, floating offshore wind turbines have attracted more attention as a new renewable energy resource while bottom-fixed offshore wind turbines reach their limit of water depth. Various projects have been proposed with the rapid increase in installed floating wind power capacity, but the economic aspect remains as a biggest issue. To figure out sensible approaches for saving costs, a comparison analysis of the levelized cost of electricity (LCOE) between floating and bottom-fixed offshore wind turbines was carried out. The LCOE was reviewed from a social perspective and a cost breakdown and a literature review analysis were used to itemize the costs into its various components in each level of power plant and system integration. The results show that the highest proportion in capital expenditure of a floating offshore wind turbine results in the substructure part, which is the main difference from a bottom-fixed wind turbine. A floating offshore wind turbine was found to have several advantages over a bottom-fixed wind turbine. Although a similarity in operation and maintenance cost structure is revealed, a floating wind turbine still has the benefit of being able to be maintained at a seaport. After emphasizing the cost-reduction advantages of a floating wind turbine, its LCOE outlook is provided to give a brief overview in the following years. Finally, some estimated cost drivers, such as economics of scale, wind turbine rating, a floater with mooring system, and grid connection cost, are outlined as proposals for floating wind LCOE reduction.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.3
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• pp.239-245
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• 2017

As a new technical approach, wave energy converter by using vertical motion of water in the multiple water chambers were developed to realize actual wave power generation as eco-environmental renewable energy. And practical use of wave energy converter was actually to require the following conditions: (1) setting up of the relevant device and its application to wave power generation in case that severe wave loading is avoided; (2) workability in installation and maintenance operations; (3) high energy conversion potential; and (4) low cost. In this system, neither the wall(s) of the chambers nor the energy conversion device(s) are exposed to the impulsive load due to water wave. Also since this system is profitable when set along the jetty or along a long floating body, installation and maintenance are done without difficulty and the cost is reduced. In this paper, we describe the system which consists of a float, a shaft connected with another shaft, a rack and pinion arrangement, a ratchet mechanism, and rotary type generator(s). Then, we present the dynamics model for evaluating the output electric power, and the results of numerical calculation including the effect of the phase shift of up/down motion of the water in the array of water chambers aligned along the direction of wave propagation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.43-49
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• 2013

The use of ocean thermal energy conversion (OTEC) to generate electricity is one of the methods proposed to utilize renewable energy and to protect the environment. In this study, simulations were performed to investigate the effect of weather conditions in the Ulsan region, Korea, on the efficiency of a solar-heating OTEC (SH-OTEC) system. This system utilizes solar thermal energy as the secondary heat source. Various working fluids were also simulated to select one that is suitable for this system. The results showed that R152A, R600, and R600A, in that order, were the most suitable working fluids. The effective area of the solar collector for a $20^{\circ}C$ increase in the collector outlet temperature fluctuated from 50 to $97m^2$ owing to the change in the monthly average solar gain. The annual average efficiency of the SH-OTEC increases to 6.23%, compared to that of a typical conventional OTEC, which is 2-4%.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.57-63
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• 2015

Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.

• Ocean Systems Engineering
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• v.12 no.1
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• pp.39-61
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• 2022

Renewable energy such as wave energy has gained popularity as a means of reducing greenhouse gases. However, the high cost and lack of available sea space in some countries have hindered the deployment of wave energy converters (WEC) as alternative means of sustainable energy production. By combining WECs with infrastructures such as floating breakwaters or piers, the idea of electricity generated from WECs will be more appealing. This paper considers the integration of vertical raft-type WEC (commonly known as the vertical flap WEC) with floating breakwater as means to generate electricity and attenuate wave force in the tropical sea. An array of 25 WECs attached to a floating breakwater is considered where their performance and effect on the wave climate are presented. The effects of varying dimensions of the WEC and mooring system of the floating breakwater have on the energy generation are investigated. The integrated WECs and floating breakwater is subjected to both the regular and irregular waves in the tropical sea to assess the performance of the system. The result shows that the integrated vertical flap-floating breakwater system can generate a substantial amount of wave energy and at the same time attenuate the wave force effectively for the tropical sea when optimal dimensions of the WECs are used.