• Journal of the Society of Naval Architects of Korea
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• v.35 no.2
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• pp.38-50
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• 1998

In order to understand the characteristics of floating breakwaters we planned series of experimental and numerical investigations and completed the first stage which is the experiment with fred pontoons near the free surface. As controlling parameters the draft and breadth of pontoon were varied and the wave frequency and steepness were also varied. Wave transmission and forces exiled on the breakwater were experimentally investigated and compared with the results computed based on linear potential theory. Discussions made are on the effect of draft and wave length on the wave transmission and force in fixed pontoon case. The predicted and measured results show quantitatively good agreement both in forces and transmission coefficient. The effect of separation distance between two pontoons on the wave transmission and force in array case is also examined.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.1-7
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• 2007

Based on the eigenfunction expansion method, the wave-absorbing performance of a square or circular pile breakwater was investigated. Flow separation resulting from sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of an exact energy loss coefficient is critical to enhancing the reliability of the mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code, and the energy loss coefficient can be obtained from the pressure difference between upstream and downstream. It was found that energy loss coefficient of circular pile is 20% that of a square pile. To validate the fitting equation for the energy loss coefficient, comparison between the analytical results and the experimental results (Kakuno and Liu, 1993) was made for square and circular piles with good agreement. The array of square piles also provides better wave-absorbing efficiency than the circular piles, and the optimal porosity value is near P=0.1.

• Journal of Ocean Engineering and Technology
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• v.31 no.5
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• pp.325-334
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• 2017

This paper reports the conceptual design process for a floating metocean data measurement system (FMDMS) for measuring wind information at sea. The FMDMS consists of three circular pontoons, columns, and a deck, which the LiDAR (lighting detection and ranging) is installed on. The dynamics of the mooring lines and motion responses of the FMDMS were analyzed using commercial codes such as WAMIT and OrcaFlex. One design criterion of the developed FMDMS was to maintain the motion responses as small as possible to enhance the LiDAR's accuracy. Starting with the preliminary design parameters such as the FMDMS's principal dimensions, weight, and important parameters of mooring system, we checked whether the FMDMS met the design requirements at each design stage, and then made modifications as necessary. The developed FMDMS showed a large pitch behavior for a small heave motion.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.89-95
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• 2006

This study was conducted to improve an effect of phosphorus removal using FNR(Ferrous Nutrient Removal) process which had iron precipitation reactor and to analyze the iron corrosion. For simultaneous removal of phosphorus, iron electrolysis was combined with oxic tank. In this study, The removal efficiency of phosphorus increased with an increase voltage in iron precipitation reactor. The distance of 15mm between the two iron bed in each tests influence the concentration of remaining phosphorus most. The extensive surface area of iron bed is the more removes the phosphorus. In this test the $400\;cm^2$ of surface area was proved to be the most removal efficient.

• Journal of Environmental Impact Assessment
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• v.12 no.3
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• pp.211-228
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• 2003

Most environmental impact assessment(EIA) programs around the world require the consideration of human health impacts. Yet relatively few EIA documents adequately address those impacts. This article examines how, why, and to what extent health impacts are analyzed in environmental impact assessments. This article investigates these problems and provides recommendations to improve human health impact assessment(HIA), using methods, procedures and case study. Also, a comprehensive approach for the evaluation of possible health effects in an EIA is described, illustrated with the example of Amsterdam Airport Schiphol. Unlike many EIAs, we estimated quantitatively the impact of aircraft-related pollution in terms of the number of affected people for aircraft noise annoyance, odour annoyance and hypertension. In addition, an analysis of health registry data on cardiovascular and respiratory diseases and a short survey on annoyance and risk perception were carried out.

• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.9-16
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• 2011

The feasibility of wave energy extraction from a heaving truncated cylinder and the corresponding response of the linear electric generator (LEG) composed of spring, magnet, and coil has been investigated in the frame of three-dimensional linear potential theory. The heaving motion of a circular cylinder is calculated by means of the matched eigenfunction expansion method. Further, the analytical results are validated by numerical results using the ANSYS AQWA commercial code. By the action of a heaving circular cylinder, the magnet suspended by a spring can slide vertically inside the heaving cylinder. The mechanical power is extracted from the magnet motion relative to the coil/stator which is attached to the cylinder. The coupled ODE of a heaving cylinder and LEG system in waves is derived to obtain the magnet motion relative to a cylinder. To maximize the relative motion of the magnet, both the buoy draft and the LEG system parameters (spring stiffness, damping) should be selected properly for generating the double resonance considering the peak frequency of the target spectrum.

• Journal of Environmental Health Sciences
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• v.26 no.3
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• pp.61-68
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• 2000

The use of photo-catalytic processes in pollution abatement and resource has a significant economic importance. Therefore, the applications of photochemical oxidation of secondary effluent driven by UV, TiO2, TiO2/UV, H2O2/UV and TiO2/H2O2/UV, have been investigated in order to treat the secondary effluent from municipal sewage. Various experimental parameters such as BOD, CODcr, Nurbidity, total P, and SPC were examined in each photo-catalytic reaction system. The results showed that the application of single oxidant such as UV, TiO2 only has a minor effect on parameters reduction (CODcr, BOD, etc) to treat the secondary effluent, whereas the combinations of oxidants increase the removal efficiency. The best removal efficiency in every parameters was achieved by the combination of TiO2, H2O2 and UV. It was also found that the optimum amount of TiO2 for the treatment was 1g/ι to achieve water reuse standard. From the results, the photocatalytic reaction system can be an alternative as a post-treatment to treat the secondary effluent from municipal sewage.

• Journal of Environmental Health Sciences
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• v.26 no.3
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• pp.69-75
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• 2000

This study was carried out to investigate the removal of nitrogen and phosphorus in municipal sewage according to the variation of volumetric ratio in the reactor. It also was performed to provide basic data necessary to the development and improvement of the process which is Anaerobic-Anoxic-Oxic(A2O). In the removal of BOD and COD, the best efficiency of the process showed in the condition of using the media, 1Q of internal recycle rate and 1:3:2 of the volumetric ratio in Anaerobic-Anoxic-Oxic process. In most cases, nitrogen and phosphorus removal efficiency of the process using the cilia media was superior to that of the process which didn't use the media. In the removal of T-N and T-P, the best efficiency of the process showed in the condition of using the media, 1Q of internal recycle rate and 1:3:2 of the volumetric ratio in Anaerobic-Anoxic-Oxic process.

• Korean Institute of Interior Design Journal
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• v.16 no.1 s.60
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• pp.65-72
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• 2007

Various residential patterns, which can accommodate ever-changing modem lifestyles, are increasingly needed. On the residents' demand for flexible space, mote research should be conducted on the apartments built by the concept of flexible space. In this study, apartments of 40-60 pyeong in size built in the region of Seoul, between 1998 and 2007, are analyzed in terms of the flexible types and the unit plan composition. To reflect the changes in people's perception of residential quality-preference for a residence with a good view, over for the direction that a residence faces, more rooms are placed on the front bay. From the analyses of this study, flexible unit plans are classified into 6 types; and it was found that, as the size of apartments gets larger, the livingroom and the dinning room tend to be placed on the front bay. After grouping rooms with a similar function into the spatial zones of the master bedroom, children's room, the livingroom, and the dinning room, flexible types are analyzed in terms of the location of rooms. The results of this study will be able to contribute to establishing flexible housing culture that can accommodate the changing needs of residents.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.3
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• pp.143-150
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• 2003

Based on the eigenfunction expansion method, the interaction between monochromatic waves and a partially immersed slotted plate with a back wall has been investigated. Analytical results show that the reflection coefficients by a partially immersed slotted plate depend on the porosity, immersed depth, chamber width, incidence angle and wave frequency. It is found that the reflection coefficient has minimum value within entire frequency range when the porosity has optimal value 0.1. Comparison between the analytical results and the experimental results(Zhu,2001) of reflection coefficients is made for various chamber widths, immersed depths and wave periods with good agreement. The present analytic method can account adequately for energy dissipation caused by flow separation behind a slotted plate and provide the design informations for the construction of slit caisson breakwater.