The coast along the Sea of Okhotsk in Hokkaido is an area greatly affected by freezing and drift ice.
It is well known that the ice floe moved by winds, currents or waves has various influences on the sea bottom along the coast of such a sea area. For example, fish reefs at the sea-bottom are broken by the drift ice, or seaweed is detached in rocky sea areas. Furthermore, it has been reported that Hokkaido clams are dying out because of the pressure of sea ice. Theleft-lettore, it is very important for the planing and designing of undersea pipelines, undersea water-intake/drains, and coast/offshore structures which are constructed along this coast area to know the amount of deformation of the sea-bottom caused by the sea ice. This study is an theoretical approach concerning the interaction between the horizontal movement of sea ice and the sea-bottom along the coast area.

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Corrosion deterioration of civil engineering steel structures, such as steel pile piers and sheet pile walls in marine environments, has lately become of interest, and many unsolved problems on corrosion deterioration of the structures are now under investigation in various organizations.
At first, we investigated the actual state of steel pile piers and sheet pile walls in port facilities, and developed a corrosion data-base of the structures. Next, we related the data-base to an expert system for corrosion deterioration assessment of the structures, which had some functions, such as stress check up, judgement of maintenance step, and life time prediction.
In this paper, we described the data-base, and the outline of the whole advising system for corrosion deterioration assessment.

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Recently people become to attach importance to the amenity in their living environment.
In these background, it is necessary to advance the assessment method, which can forcast and evaluate various landscape effects of power plants. In order to evaluate the design of form, color and texture of power plant facilities, we extracted four criteria, the sence of “beauty”, “elegance”, “conpactness” and “stability”, through the psychometric experiment.

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Marine mac rophyte bed, especially, kelp forest consisting of Ecklonia cava is important for production of fishery resources and conservation of marine environmert.
1. Populations of E.cava were recognised on no-sand-covered concrete brocks set tedat suitable place in sandy sea bottom.
2. At projection on surface of corrcrete brocks, effect for survive of E. cava was observed.
3. Adheric power of plants growing at projection was largere than those at flat area.
4.Concrete brocks will be advantageous for artificial algal substratum;because of theier processablity, especially, favable size and form.

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Fishing ports are the productive base of fishing industry, and fishing port structures are essential to the operation of the industry. However, their construction sometimes causes harmful impact on fishing environment:loss of seaweed bed and fishing grounds, inhibition of seawater exchange, interruption and changing of fishways.
Not only to lessen these kinds of effects, but also to promote fishing environmental improvement through utilization of fishing port structures, the following points are discussed.
1)Enhancement of water exchange within the port
2)Creation of new site for seaweed bed
3)Attraction for desirable marine life
This paper enumerates several proposals and claims the necessity of field survey on actual fishing port structure with such devices.

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Natural environment should be effectively preserved from destruction in waterfront development. This study deals with the sound of water waves which constitutes one of the indexes of comfort in coastal areas. The listening test with both the artificial sound with pink noise spectra and the sound of actual water waves at Tokushima coasts was carried out to evaluate the mental comfort as to three sound-wave properties of timbre, rhythm and period. In concl usi on, we found the characteristics of the most comfortable sound of water waves; especially, the sound of water waves with the period range of 6-8 seconds was felt most pleasant.

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The purpose of this study is to investigate the feasibility of water exchange in a closed basin by the wave overtopping and the tide. The calculated amount of water exchange by the tide is larger than any other amounts in this study in case that both new and old waterways have respective flap-gates. When the tide level is nearly equal to the top of submerged breakwater, the wave overtopping amountover it is comparable with the above mentioned amount by the tide.

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Strong convection can be produced by placing a v-shape plate against a horizontal flow. Vortices shed from the plate and coalesce with neighboring ones to from a horse-shoe shaped vortex. The self-induced upward motion produced due to the shape and the flow converging and surmounting the plate raises the Vortex head, resulting the formation of the Vertical convection below.The maximum height can be attained with the dihedral angle of 90°. Al though this height decreases in the stratification, the V-shape effect works efficiently.

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Recently, the problems of environment becomes one of the biggest problems for human in the world. Even in the area of offshore and coastal zone, we can see a lot of problems of contamination of sea water, mud and shore. In order to improve such contamination, we should not use the electric power generated by the fuel, coal or nuclear power plant, because such plant causes another and more serious “pollution”. Fortunately, we can use the natural energy resources in ocean, such as wave energy. Consequently, authors proposes to utilize wave energy for the improvement of the coastal environment efficiently. Wave power device “the Mighty Whale” which was designed and tested by authors should be used for the generation of air power, and it rotates an air turbine and an air compressor to generate the compressed air. The compressed air is storaged in the tank which is installed on the sea bottom, and air pipe line is connected from the tank to the shore for the aeration. It makes sea water to be left-lettresh efficiently.
Authors introduce out line of this concept and propose to utilize the system for the environmental problems at the offing and coastal zone.

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