• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.4
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• pp.199-204
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• 2016

This paper was proposed floating island power MOSFET for lowering on state resistance and the proposed device was maintained 600 V breakdown voltage. The electrical field distribution of floating island power MOSFET was dispersed to floating island between P-base and N-drift. Therefore, we designed higher doping concentration of drift region than doping concentration of planar type power MOSFET. And so we obtain the lower on resistance than on resistance of planar type power MOSFET. We needed the higher doping concentration of floating island than doping concentration of drift region and needed width and depth of floating island for formation of floating island region. We obtained the optimal parameters. The depth of floating island was $32{\mu}m$. The doping concentration of floating island was $5{\times}1,012cm^2$. And the width of floating island was $3{\mu}m$. As a result of designing the floating island power MOSFET, we obtained 723 V breakdown voltage and $0.108{\Omega}cm^2$ on resistance. When we compared to planar power MOSFET, the on resistance was lowered 24.5% than its of planar power MOSFET. The proposed device will be used to electrical vehicle and renewable industry.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.523-526
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• 2016

This paper was researched about 1,200 V level floating island IGBT (insulated gate bipolar transistor). Presently, 1,200 V level IGBT is used in Inverter for distributed power generation. We analyzed and compared electrical charateristics of the proposed floating island IGBT and conventional IGBT. For analyzing and comparison, we used T-CAD tool and simulated the electrical charateristics of the devices. And we extracted optimal design and process parameter of the devices. As a result of experiments, we obtained 1,456 V and 1,459 V of breakdown voltages, respectively. And we obatined 4.06 V and 4.09 V of threshold voltages, respectively. On the other hand, on-state voltage drop of floating island IGBT was 3.75 V. but on-state vlotage drop of the conventional IGBT was 4.65 V. Therefore, we almost knew that the proposed floating island IGBT was superior than the conventional IGBT in terms of power dissipation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.222-228
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• 2015

Power MOSFETs (metal oxide semiconductor field effect transistor) operate as energy control semiconductor switches. In order to reduce energy loss of the device, it is essential to increase its conductance. However, a trade-off relationship between the breakdown voltage and conductance of the device have been the critical difficulty to improve. In this paper, theoretical analysis of electrical benefits on single floating island power MOSFET is proposed. By the method, the optimization point has set defining the doping limit under single floating island structure. The numerical multiple 2.22 was obtained which indicates the doping limit of the original device, improving its ON state voltage drop by 45%.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.825-835
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• 2012

This study for the development of water purification Artificial floating island maximizing domestic Artificial floating island patent trends and product development, according to the timing of patent registration was analyzed for trends. In addition, domestic invention patent technology Artificial floating island typed according to the purpose and characteristics of domestic patents were Artificial Floating Island. In particular, domestic leisure space with a growing population and the need for securing emerging role as a reservoir of water only in the past, who do appeal as a tourist destination or as an ecological space utilized, and accordingly will transform and the need to secure a hydrophilic, degrade water quality problems using this aquatic environment (water acquisition and hydrophilic), the requirements are a big obstacle is the reality factor. This patented product differentiation strategy through the analysis of the development of technology progressiveness (Field Application) in terms of water quality improvement and maintenance side, and the hydrophilic side scenery, ecological restoration aspects, and applicability to the field and taking into account existing technology economic aspects of distinction were presented and advertised a lot in terms of cost compared to other techniques without the use of highly efficient methodology for building a water purification and also appears identity appeal, wetlands, rivers, etc. can be applied broadly technician widespread deployment and installation time to less simple and more are expected to spread.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.247-252
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• 2012

IGBT (insulated gate bipolar transistor) has been widely used around the power industry as it has good switching performance and its excellent conductance. In order to reduce power loss during switch turn-on state, it is essential to reduce its resistance. However, trade off relationship between breakdown voltage and device conductance is the greatest obstacle on the way of improvement. Floating island structure is one of the solutions. Still, under optimized device condition for the best performance, improvement rate is negligible. Therefore, this paper suggests adding trench gate on floating island structure to eliminate JFET (junction field effect transistor) area to reduce resistance and activate floating island effect. Experimental result by 2D simulation using TCAD, shows 20% improvement of turn-on state voltage drop.

• Journal of Ocean Engineering and Technology
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• v.37 no.1
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• pp.8-19
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• 2023

In recent years, modular-type floating islands have been considered as a promising option for future ocean space utilization. A modular floating island consists of a number of standardized pontoon-type modules and connectors between them. In this study, the motion responses of a modular floating island in waves was investigated based on frequency-domain numerical analysis. The numerical method is based on the potential flow theory and adopts a higher-order boundary element method with Green's function. First, motion RAOs were directly compared with the model test data by reference to validate the present numerical method. Then, numerical investigations were conducted to analyze the motion characteristics of the floating island by considering various modules shapes and arrangements. It was found that motion responses were reduced in a single central module compared to when divided central modules were used. Finally, the effect of modular arrangement on the motion responses in irregular waves was discussed. It was confirmed that multiple-layer outer modules are more effective in calming the central module than using single-layer outer modules, except under very long period conditions.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.1
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• pp.90-97
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• 2001

For improvement of water quality, $20m^2$ of artificial floating plant islands planted with Iris pseudoacorus, were installed in small pond on March, 1999. Small pond has surface area $1,000m^2$ and mean depth 1.5 m. The density of plants was 16 per $m^2$ by using jute pot. Environmental parameters such as COD, SS, T-N, T-P and planktons were biweekly measured from 29 March to 28 September. Because of the small portion of floating island, the effect for water quality improvement was not sufficient. But considering the data of plant growth and nitrogen and phosphorus uptake capacity of plant, about 40% of coverage by artificial floating island was needed for elimination of whole nutrients from inflow.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.2
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• pp.84-91
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• 2001

This study was carried out to develop the technology of artificial floating island for the wild-life habitat at the reservoir of Korea University farm near Seoul. After the execution of an artificial floating island with 6 cells(each $3{\times}3m$), each cell was planted with 5 different species and one mixed of them, to the reservoir in 1999 through 2000. The monitored results were as follows; 1. Typha orientalis, Zizania latifolia and Oenanthe japonica were died back, but Phragmites communis, Phragmites japonica and Juncus effusus var. decipiens were well growing. 2. The limits of sinking water depth of the planting foundation were different with the plant species, that is, 40cm to the Juncus effusus var. dicipiens and 50cm to Phragmites communis. Accordingly the water depth should be kept differently with each species. 3. 33 species of fauna were monitored in the first year(1999) and 43 species in the second (2000) increasingly. 4. For the more wild-lives inducing to the artificial floating island, establishing the eco-corridor from the surrounding environment was needed.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1038-1044
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• 2006

The floating island was investigated in order to make a purification of lake water quality with the uptake of nutrients, the prevention of algae growth and the supply of habitat for aquatic plants. Although the concentrations of organics and nutrients inside facility were shown higher than outside, the quantitative analysis was not attainable. Nitrogen uptakes by Cattail, Phragmites japonica, Reed and Wild rice were shown 48.2, 98.0, 111.1 and $72.0g/m^2{\cdot}year$, respectively, and in the case of phosphorus they were 3.2, 8.3, 6.1 and $4.6g/m^2{\cdot}year$, respectively. Considering total floating areas of $2,560m^2$, the nitrogen uptake is totally estimated to $210.7kg/m^2{\cdot}year$ and $14.2kg/m^2{\cdot}year$ for the phosphorus uptake. In order to promote the spread of floating island, the selection of aquatic plants, the control of growth rate properly and the method of quantitative analysis for the purification of water quality and the application to the stream water should be thoroughly surveyed from all angles prior to the application.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.19-25
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• 2009

The effects of artificial floating island on the changes in phytoplankton and zooplankton community structure were investigated monthly from September 2006 to May 2007 in Shingu reservoir. The total cell number of phytoplankton under the artificial floating island was three times less than those of control (without artificial floating island). The dominant species of phytoplankton were Lyngbya sp. on September, Cryptomonas sp. from October to January, Aulacoseira granulata on February and Oscillatoria sp. from March to May at lake water. Cyanophyta was dominated from February to March at lake water but it was dominated from March at artificial floating island area. The total individual number, species number of zooplankton and species diversity of phytoplankton and zooplankton under the artificial floating island were higher than those of lake water.